Daniel Isaac, DO, MS

Study 1 Overview (Bretthauer et al) 

Objective: To evaluate the impact of screening colonoscopy on colon cancer–related death. 

Design: Randomized trial conducted in 4 European countries.

Setting and participants: Presumptively healthy men and women between the ages of 55 and 64 years were selected from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. Eligible participants had not previously undergone screening. Patients with a diagnosis of colon cancer before trial entry were excluded.

Intervention: Participants were randomly assigned in a 1:2 ratio to undergo colonoscopy screening by invitation or to no invitation and no screening. Participants were randomized using a computer-generated allocation algorithm. Patients were stratified by age, sex, and municipality.

Main outcome measures: The primary endpoint of the study was risk of colorectal cancer and related death after a median follow-up of 10 to 15 years. The main secondary endpoint was death from any cause.

Main results: The study reported follow-up data from 84,585 participants (89.1% of all participants originally included in the trial). The remaining participants were either excluded or data could not be included due to lack of follow-up data from the usual-care group. Men (50.1%) and women (49.9%) were equally represented. The median age at entry was 59 years. The median follow-up was 10 years. Characteristics were otherwise balanced. Good bowel preparation was reported in 91% of all participants. Cecal intubation was achieved in 96.8% of all participants. The percentage of patients who underwent screening was 42% for the group, but screening rates varied by country (33%-60%). Colorectal cancer was diagnosed at screening in 62 participants (0.5% of screening group). Adenomas were detected in 30.7% of participants; 15 patients had polypectomy-related major bleeding. There were no perforations.

The risk of colorectal cancer at 10 years was 0.98% in the invited-to-screen group and 1.2% in the usual-care group (risk ratio, 0.82; 95% CI, 0.7-0.93). The reported number needed to invite to prevent 1 case of colon cancer in a 10-year period was 455. The risk of colorectal cancer–related death at 10 years was 0.28% in the invited-to-screen group and 0.31% in the usual-care group (risk ratio, 0.9; 95% CI, 0.64-1.16). An adjusted per-protocol analysis was performed to account for the estimated effect of screening if all participants assigned to the screening group underwent screening. In this analysis, the risk of colorectal cancer at 10 years was decreased from 1.22% to 0.84% (risk ratio, 0.69; 95% CI, 0.66-0.83).

Conclusion: Based on the results of this European randomized trial, the risk of colorectal cancer at 10 years was lower among those who were invited to undergo screening.

Study 2 Overview (Forsberg et al) 

Objective: To investigate the effect of colorectal cancer screening with once-only colonoscopy or fecal immunochemical testing (FIT) on colorectal cancer mortality and incidence.

Design: Randomized controlled trial in Sweden utilizing a population registry. 

Setting and participants: Patients aged 60 years at the time of entry were identified from a population-based registry from the Swedish Tax Agency.

Intervention: Individuals were assigned by an independent statistician to once-only colonoscopy, 2 rounds of FIT 2 years apart, or a control group in which no intervention was performed. Patients were assigned in a 1:6 ratio for colonoscopy vs control and a 1:2 ratio for FIT vs control.

Main outcome measures: The primary endpoint of the trial was colorectal cancer incidence and mortality.

Main results: A total of 278,280 participants were included in the study from March 1, 2014, through December 31, 2020 (31,140 in the colonoscopy group, 60,300 in the FIT group, and 186,840 in the control group). Of those in the colonoscopy group, 35% underwent colonoscopy, and 55% of those in the FIT group participated in testing. Colorectal cancer was detected in 0.16% (49) of people in the colonoscopy group and 0.2% (121) of people in the FIT test group (relative risk, 0.78; 95% CI, 0.56-1.09). The advanced adenoma detection rate was 2.05% in the colonoscopy group and 1.61% in the FIT group (relative risk, 1.27; 95% CI, 1.15-1.41). There were 2 perforations noted in the colonoscopy group and 15 major bleeding events. More right-sided adenomas were detected in the colonoscopy group.

Conclusion: The results of the current study highlight similar detection rates in the colonoscopy and FIT group. Should further follow-up show a benefit in disease-specific mortality, such screening strategies could be translated into population-based screening programs.

Commentary 

The first colonoscopy screening recommendations were established in the mid 1990s in the United States, and over the subsequent 2 decades colonoscopy has been the recommended method and main modality for colorectal cancer screening in this country. The advantage of colonoscopy over other screening modalities (sigmoidoscopy and fecal-based testing) is that it can examine the entire large bowel and allow for removal of potential precancerous lesions. However, data to support colonoscopy as a screening modality for colorectal cancer are largely based on cohort studies.^1,2 These studies have reported a significant reduction in the incidence of colon cancer. Additionally, colorectal cancer mortality was notably lower in the screened populations. For example, one study among health professionals found a nearly 70% reduction in colorectal cancer mortality in those who underwent at least 1 screening colonoscopy.³

There has been a lack of randomized clinical data to validate the efficacy of colonoscopy screening for reducing colorectal cancer–related deaths. The current study by Bretthauer et al addresses an important need and enhances our understanding of the efficacy of colorectal cancer screening with colonoscopy. In this randomized trial involving more than 84,000 participants from Poland, Norway, Sweden, and the Netherlands, there was a noted 18% decrease in the risk of colorectal cancer over a 10-year period in the intention-to-screen population. The reduction in the risk of death from colorectal cancer was not statistically significant (risk ratio, 0.90; 95% CI, 0.64-1.16). These results are surprising and certainly raise the question as to whether previous studies overestimated the effectiveness of colonoscopy in reducing the risk of colorectal cancer–related deaths. There are several limitations to the Bretthauer et al study, however.

Perhaps the most important limitation is the fact that only 42% of participants in the invited-to-screen cohort underwent screening colonoscopy. Therefore, this raises the question of whether the efficacy noted is simply due to a lack of participation in the screening protocol. In the adjusted per-protocol analysis, colonoscopy was estimated to reduce the risk of colorectal cancer by 31% and the risk of colorectal cancer–related death by around 50%. These findings are more in line with prior published studies regarding the efficacy of colorectal cancer screening. The authors plan to repeat this analysis at 15 years, and it is possible that the risk of colorectal cancer and colorectal cancer–related death can be reduced on subsequent follow-up.

While the results of the Bretthauer et al trial are important, randomized trials that directly compare the effectiveness of different colorectal cancer screening strategies are lacking. The Forsberg et al trial, also an ongoing study, seeks to address this vitally important gap in our current data. The SCREESCO trial is a study that compares the efficacy of colonoscopy with FIT every 2 years or no screening. The currently reported data are preliminary but show a similarly low rate of colonoscopy screening in those invited to do so (35%). This is a similar limitation to that noted in the Bretthauer et al study. Furthermore, there is some question regarding colonoscopy quality in this study, which had a very low reported adenoma detection rate.

While the current studies are important and provide quality randomized data on the effect of colorectal cancer screening, there remain many unanswered questions. Should the results presented by Bretthauer et al represent the current real-world scenario, then colonoscopy screening may not be viewed as an effective screening tool compared to simpler, less-invasive modalities (ie, FIT). Further follow-up from the SCREESCO trial will help shed light on this question. However, there are concerns with this study, including a very low participation rate, which could greatly underestimate the effectiveness of screening. Additional analysis and longer follow-up will be vital to fully understand the benefits of screening colonoscopy. In the meantime, screening remains an important tool for early detection of colorectal cancer and remains a category A recommendation by the United States Preventive Services Task Force.⁴ 

Applications for Clinical Practice and System Implementation

Current guidelines continue to strongly recommend screening for colorectal cancer for persons between 45 and 75 years of age (category B recommendation for those aged 45 to 49 years per the United States Preventive Services Task Force). Stool-based tests and direct visualization tests are both endorsed as screening options. Further follow-up from the presented studies is needed to help shed light on the magnitude of benefit of these modalities.

Practice Points

• Current guidelines continue to strongly recommend screening for colon cancer in those aged 45 to 75 years.
• The optimal modality for screening and the impact of screening on cancer-related mortality requires longer- term follow-up from these ongoing studies.

–Daniel Isaac, DO, MS 

Study 1 Overview (Bretthauer et al) 

Objective: To evaluate the impact of screening colonoscopy on colon cancer–related death. 

Design: Randomized trial conducted in 4 European countries.

Setting and participants: Presumptively healthy men and women between the ages of 55 and 64 years were selected from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. Eligible participants had not previously undergone screening. Patients with a diagnosis of colon cancer before trial entry were excluded.

Intervention: Participants were randomly assigned in a 1:2 ratio to undergo colonoscopy screening by invitation or to no invitation and no screening. Participants were randomized using a computer-generated allocation algorithm. Patients were stratified by age, sex, and municipality.

Main outcome measures: The primary endpoint of the study was risk of colorectal cancer and related death after a median follow-up of 10 to 15 years. The main secondary endpoint was death from any cause.

Main results: The study reported follow-up data from 84,585 participants (89.1% of all participants originally included in the trial). The remaining participants were either excluded or data could not be included due to lack of follow-up data from the usual-care group. Men (50.1%) and women (49.9%) were equally represented. The median age at entry was 59 years. The median follow-up was 10 years. Characteristics were otherwise balanced. Good bowel preparation was reported in 91% of all participants. Cecal intubation was achieved in 96.8% of all participants. The percentage of patients who underwent screening was 42% for the group, but screening rates varied by country (33%-60%). Colorectal cancer was diagnosed at screening in 62 participants (0.5% of screening group). Adenomas were detected in 30.7% of participants; 15 patients had polypectomy-related major bleeding. There were no perforations.

The risk of colorectal cancer at 10 years was 0.98% in the invited-to-screen group and 1.2% in the usual-care group (risk ratio, 0.82; 95% CI, 0.7-0.93). The reported number needed to invite to prevent 1 case of colon cancer in a 10-year period was 455. The risk of colorectal cancer–related death at 10 years was 0.28% in the invited-to-screen group and 0.31% in the usual-care group (risk ratio, 0.9; 95% CI, 0.64-1.16). An adjusted per-protocol analysis was performed to account for the estimated effect of screening if all participants assigned to the screening group underwent screening. In this analysis, the risk of colorectal cancer at 10 years was decreased from 1.22% to 0.84% (risk ratio, 0.69; 95% CI, 0.66-0.83).

Conclusion: Based on the results of this European randomized trial, the risk of colorectal cancer at 10 years was lower among those who were invited to undergo screening.

Study 2 Overview (Forsberg et al) 

Objective: To investigate the effect of colorectal cancer screening with once-only colonoscopy or fecal immunochemical testing (FIT) on colorectal cancer mortality and incidence.

Design: Randomized controlled trial in Sweden utilizing a population registry. 

Setting and participants: Patients aged 60 years at the time of entry were identified from a population-based registry from the Swedish Tax Agency.

Intervention: Individuals were assigned by an independent statistician to once-only colonoscopy, 2 rounds of FIT 2 years apart, or a control group in which no intervention was performed. Patients were assigned in a 1:6 ratio for colonoscopy vs control and a 1:2 ratio for FIT vs control.

Main outcome measures: The primary endpoint of the trial was colorectal cancer incidence and mortality.

Main results: A total of 278,280 participants were included in the study from March 1, 2014, through December 31, 2020 (31,140 in the colonoscopy group, 60,300 in the FIT group, and 186,840 in the control group). Of those in the colonoscopy group, 35% underwent colonoscopy, and 55% of those in the FIT group participated in testing. Colorectal cancer was detected in 0.16% (49) of people in the colonoscopy group and 0.2% (121) of people in the FIT test group (relative risk, 0.78; 95% CI, 0.56-1.09). The advanced adenoma detection rate was 2.05% in the colonoscopy group and 1.61% in the FIT group (relative risk, 1.27; 95% CI, 1.15-1.41). There were 2 perforations noted in the colonoscopy group and 15 major bleeding events. More right-sided adenomas were detected in the colonoscopy group.

Conclusion: The results of the current study highlight similar detection rates in the colonoscopy and FIT group. Should further follow-up show a benefit in disease-specific mortality, such screening strategies could be translated into population-based screening programs.

Commentary 

The first colonoscopy screening recommendations were established in the mid 1990s in the United States, and over the subsequent 2 decades colonoscopy has been the recommended method and main modality for colorectal cancer screening in this country. The advantage of colonoscopy over other screening modalities (sigmoidoscopy and fecal-based testing) is that it can examine the entire large bowel and allow for removal of potential precancerous lesions. However, data to support colonoscopy as a screening modality for colorectal cancer are largely based on cohort studies.^1,2 These studies have reported a significant reduction in the incidence of colon cancer. Additionally, colorectal cancer mortality was notably lower in the screened populations. For example, one study among health professionals found a nearly 70% reduction in colorectal cancer mortality in those who underwent at least 1 screening colonoscopy.³

There has been a lack of randomized clinical data to validate the efficacy of colonoscopy screening for reducing colorectal cancer–related deaths. The current study by Bretthauer et al addresses an important need and enhances our understanding of the efficacy of colorectal cancer screening with colonoscopy. In this randomized trial involving more than 84,000 participants from Poland, Norway, Sweden, and the Netherlands, there was a noted 18% decrease in the risk of colorectal cancer over a 10-year period in the intention-to-screen population. The reduction in the risk of death from colorectal cancer was not statistically significant (risk ratio, 0.90; 95% CI, 0.64-1.16). These results are surprising and certainly raise the question as to whether previous studies overestimated the effectiveness of colonoscopy in reducing the risk of colorectal cancer–related deaths. There are several limitations to the Bretthauer et al study, however.

Perhaps the most important limitation is the fact that only 42% of participants in the invited-to-screen cohort underwent screening colonoscopy. Therefore, this raises the question of whether the efficacy noted is simply due to a lack of participation in the screening protocol. In the adjusted per-protocol analysis, colonoscopy was estimated to reduce the risk of colorectal cancer by 31% and the risk of colorectal cancer–related death by around 50%. These findings are more in line with prior published studies regarding the efficacy of colorectal cancer screening. The authors plan to repeat this analysis at 15 years, and it is possible that the risk of colorectal cancer and colorectal cancer–related death can be reduced on subsequent follow-up.

While the results of the Bretthauer et al trial are important, randomized trials that directly compare the effectiveness of different colorectal cancer screening strategies are lacking. The Forsberg et al trial, also an ongoing study, seeks to address this vitally important gap in our current data. The SCREESCO trial is a study that compares the efficacy of colonoscopy with FIT every 2 years or no screening. The currently reported data are preliminary but show a similarly low rate of colonoscopy screening in those invited to do so (35%). This is a similar limitation to that noted in the Bretthauer et al study. Furthermore, there is some question regarding colonoscopy quality in this study, which had a very low reported adenoma detection rate.

While the current studies are important and provide quality randomized data on the effect of colorectal cancer screening, there remain many unanswered questions. Should the results presented by Bretthauer et al represent the current real-world scenario, then colonoscopy screening may not be viewed as an effective screening tool compared to simpler, less-invasive modalities (ie, FIT). Further follow-up from the SCREESCO trial will help shed light on this question. However, there are concerns with this study, including a very low participation rate, which could greatly underestimate the effectiveness of screening. Additional analysis and longer follow-up will be vital to fully understand the benefits of screening colonoscopy. In the meantime, screening remains an important tool for early detection of colorectal cancer and remains a category A recommendation by the United States Preventive Services Task Force.⁴ 

Applications for Clinical Practice and System Implementation

Current guidelines continue to strongly recommend screening for colorectal cancer for persons between 45 and 75 years of age (category B recommendation for those aged 45 to 49 years per the United States Preventive Services Task Force). Stool-based tests and direct visualization tests are both endorsed as screening options. Further follow-up from the presented studies is needed to help shed light on the magnitude of benefit of these modalities.

Practice Points

• Current guidelines continue to strongly recommend screening for colon cancer in those aged 45 to 75 years.
• The optimal modality for screening and the impact of screening on cancer-related mortality requires longer- term follow-up from these ongoing studies.

–Daniel Isaac, DO, MS 

Study 1 Overview (Bretthauer et al) 

Objective: To evaluate the impact of screening colonoscopy on colon cancer–related death. 

Design: Randomized trial conducted in 4 European countries.

Setting and participants: Presumptively healthy men and women between the ages of 55 and 64 years were selected from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. Eligible participants had not previously undergone screening. Patients with a diagnosis of colon cancer before trial entry were excluded.

Intervention: Participants were randomly assigned in a 1:2 ratio to undergo colonoscopy screening by invitation or to no invitation and no screening. Participants were randomized using a computer-generated allocation algorithm. Patients were stratified by age, sex, and municipality.

Main outcome measures: The primary endpoint of the study was risk of colorectal cancer and related death after a median follow-up of 10 to 15 years. The main secondary endpoint was death from any cause.

Main results: The study reported follow-up data from 84,585 participants (89.1% of all participants originally included in the trial). The remaining participants were either excluded or data could not be included due to lack of follow-up data from the usual-care group. Men (50.1%) and women (49.9%) were equally represented. The median age at entry was 59 years. The median follow-up was 10 years. Characteristics were otherwise balanced. Good bowel preparation was reported in 91% of all participants. Cecal intubation was achieved in 96.8% of all participants. The percentage of patients who underwent screening was 42% for the group, but screening rates varied by country (33%-60%). Colorectal cancer was diagnosed at screening in 62 participants (0.5% of screening group). Adenomas were detected in 30.7% of participants; 15 patients had polypectomy-related major bleeding. There were no perforations.

The risk of colorectal cancer at 10 years was 0.98% in the invited-to-screen group and 1.2% in the usual-care group (risk ratio, 0.82; 95% CI, 0.7-0.93). The reported number needed to invite to prevent 1 case of colon cancer in a 10-year period was 455. The risk of colorectal cancer–related death at 10 years was 0.28% in the invited-to-screen group and 0.31% in the usual-care group (risk ratio, 0.9; 95% CI, 0.64-1.16). An adjusted per-protocol analysis was performed to account for the estimated effect of screening if all participants assigned to the screening group underwent screening. In this analysis, the risk of colorectal cancer at 10 years was decreased from 1.22% to 0.84% (risk ratio, 0.69; 95% CI, 0.66-0.83).

Conclusion: Based on the results of this European randomized trial, the risk of colorectal cancer at 10 years was lower among those who were invited to undergo screening.

Study 2 Overview (Forsberg et al) 

Objective: To investigate the effect of colorectal cancer screening with once-only colonoscopy or fecal immunochemical testing (FIT) on colorectal cancer mortality and incidence.

Design: Randomized controlled trial in Sweden utilizing a population registry. 

Setting and participants: Patients aged 60 years at the time of entry were identified from a population-based registry from the Swedish Tax Agency.

Intervention: Individuals were assigned by an independent statistician to once-only colonoscopy, 2 rounds of FIT 2 years apart, or a control group in which no intervention was performed. Patients were assigned in a 1:6 ratio for colonoscopy vs control and a 1:2 ratio for FIT vs control.

Main outcome measures: The primary endpoint of the trial was colorectal cancer incidence and mortality.

Main results: A total of 278,280 participants were included in the study from March 1, 2014, through December 31, 2020 (31,140 in the colonoscopy group, 60,300 in the FIT group, and 186,840 in the control group). Of those in the colonoscopy group, 35% underwent colonoscopy, and 55% of those in the FIT group participated in testing. Colorectal cancer was detected in 0.16% (49) of people in the colonoscopy group and 0.2% (121) of people in the FIT test group (relative risk, 0.78; 95% CI, 0.56-1.09). The advanced adenoma detection rate was 2.05% in the colonoscopy group and 1.61% in the FIT group (relative risk, 1.27; 95% CI, 1.15-1.41). There were 2 perforations noted in the colonoscopy group and 15 major bleeding events. More right-sided adenomas were detected in the colonoscopy group.

Conclusion: The results of the current study highlight similar detection rates in the colonoscopy and FIT group. Should further follow-up show a benefit in disease-specific mortality, such screening strategies could be translated into population-based screening programs.

Commentary 

The first colonoscopy screening recommendations were established in the mid 1990s in the United States, and over the subsequent 2 decades colonoscopy has been the recommended method and main modality for colorectal cancer screening in this country. The advantage of colonoscopy over other screening modalities (sigmoidoscopy and fecal-based testing) is that it can examine the entire large bowel and allow for removal of potential precancerous lesions. However, data to support colonoscopy as a screening modality for colorectal cancer are largely based on cohort studies.^1,2 These studies have reported a significant reduction in the incidence of colon cancer. Additionally, colorectal cancer mortality was notably lower in the screened populations. For example, one study among health professionals found a nearly 70% reduction in colorectal cancer mortality in those who underwent at least 1 screening colonoscopy.³

There has been a lack of randomized clinical data to validate the efficacy of colonoscopy screening for reducing colorectal cancer–related deaths. The current study by Bretthauer et al addresses an important need and enhances our understanding of the efficacy of colorectal cancer screening with colonoscopy. In this randomized trial involving more than 84,000 participants from Poland, Norway, Sweden, and the Netherlands, there was a noted 18% decrease in the risk of colorectal cancer over a 10-year period in the intention-to-screen population. The reduction in the risk of death from colorectal cancer was not statistically significant (risk ratio, 0.90; 95% CI, 0.64-1.16). These results are surprising and certainly raise the question as to whether previous studies overestimated the effectiveness of colonoscopy in reducing the risk of colorectal cancer–related deaths. There are several limitations to the Bretthauer et al study, however.

Perhaps the most important limitation is the fact that only 42% of participants in the invited-to-screen cohort underwent screening colonoscopy. Therefore, this raises the question of whether the efficacy noted is simply due to a lack of participation in the screening protocol. In the adjusted per-protocol analysis, colonoscopy was estimated to reduce the risk of colorectal cancer by 31% and the risk of colorectal cancer–related death by around 50%. These findings are more in line with prior published studies regarding the efficacy of colorectal cancer screening. The authors plan to repeat this analysis at 15 years, and it is possible that the risk of colorectal cancer and colorectal cancer–related death can be reduced on subsequent follow-up.

While the results of the Bretthauer et al trial are important, randomized trials that directly compare the effectiveness of different colorectal cancer screening strategies are lacking. The Forsberg et al trial, also an ongoing study, seeks to address this vitally important gap in our current data. The SCREESCO trial is a study that compares the efficacy of colonoscopy with FIT every 2 years or no screening. The currently reported data are preliminary but show a similarly low rate of colonoscopy screening in those invited to do so (35%). This is a similar limitation to that noted in the Bretthauer et al study. Furthermore, there is some question regarding colonoscopy quality in this study, which had a very low reported adenoma detection rate.

While the current studies are important and provide quality randomized data on the effect of colorectal cancer screening, there remain many unanswered questions. Should the results presented by Bretthauer et al represent the current real-world scenario, then colonoscopy screening may not be viewed as an effective screening tool compared to simpler, less-invasive modalities (ie, FIT). Further follow-up from the SCREESCO trial will help shed light on this question. However, there are concerns with this study, including a very low participation rate, which could greatly underestimate the effectiveness of screening. Additional analysis and longer follow-up will be vital to fully understand the benefits of screening colonoscopy. In the meantime, screening remains an important tool for early detection of colorectal cancer and remains a category A recommendation by the United States Preventive Services Task Force.⁴ 

Applications for Clinical Practice and System Implementation

Current guidelines continue to strongly recommend screening for colorectal cancer for persons between 45 and 75 years of age (category B recommendation for those aged 45 to 49 years per the United States Preventive Services Task Force). Stool-based tests and direct visualization tests are both endorsed as screening options. Further follow-up from the presented studies is needed to help shed light on the magnitude of benefit of these modalities.

Practice Points

• Current guidelines continue to strongly recommend screening for colon cancer in those aged 45 to 75 years.
• The optimal modality for screening and the impact of screening on cancer-related mortality requires longer- term follow-up from these ongoing studies.

–Daniel Isaac, DO, MS 

Study 1 Overview (Cortés et al)

Objective: To compare the efficacy and safety of trastuzumab deruxtecan with those of trastuzumab emtansine in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab and taxane.

Design: Phase 3, multicenter, open-label randomized trial conducted at 169 centers and 15 countries.

Setting and participants: Eligible patients had to have unresectable or metastatic HER2-positive breast cancer that had progressed during or after treatment with trastuzumab and a taxane or had disease that progressed within 6 months after neoadjuvant or adjuvant treatment involving trastuzumab or taxane. Patients with stable or previously treated brain metastases were eligible. Patients were not eligible for the study if they had symptomatic brain metastases, prior exposure to trastuzumab emtansine, or a history of interstitial lung disease.

Intervention: Patients were randomized in a 1-to-1 fashion to receive either trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or trastuzumab emtansine 3.6 mg/kg every 3 weeks. Patients were stratified according to hormone-receptor status, prior treatment with epratuzumab, and the presence or absence of visceral disease.

Main outcome measures: The primary endpoint of the study was progression-free survival as determined by an independent central review. Secondary endpoints included overall survival, overall response, and safety.

Main results: A total of 524 patients were enrolled in the study, with 261 patients randomized to trastuzumab deruxtecan and 263 patients randomized to trastuzumab emtansine. The demographic and baseline characteristics were similar between the 2 cohorts, and 60% of patients in both groups received prior epratuzumab therapy. Stable brain metastases were present in around 20% of patients in each group, and 70% of patients in each group had visceral disease. The median duration of follow-up was 16.2 months with trastuzumab deruxtecan and 15.3 months with trastuzumab emtansine.

The median progression-free survival was not reached in the trastuzumab deruxtecan group and was 6.8 months in the trastuzumab emtansine group (95% CI, 5.6-8.2). At 12 months the percentage of patients alive without disease progression was significantly larger in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. The hazard ratio for disease progression or death from any cause was 0.28 (95% CI, 0.22-0.37; P < .001). Subgroup analyses showed a benefit in progression-free survival with trastuzumab deruxtecan across all subgroups.

At the time of this analysis, the percentage of patients who were alive at 12 months was 94% with trastuzumab deruxtecan and 85.9% with trastuzumab emtansine. The response rates were significantly higher with trastuzumab deruxtecan compared with trastuzumab emtansine (79.7% vs 34.2%). A complete response was seen in 16% of patients in the trastuzumab deruxtecan arm, compared with 8.7% of patients in the trastuzumab emtansine group. The disease control rate (complete response, partial response, or stable disease) was higher in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group (96.6% vs 76.8%).

Serious adverse events were reported in 19% of patients in the trastuzumab deruxtecan group and 18% of patients in the trastuzumab emtansine group. Discontinuation due to adverse events was higher in the trastuzumab deruxtecan group, with 13.6% of patients discontinuing trastuzumab deruxtecan. Grade 3 or higher adverse events were seen in 52% of patients treated with trastuzumab deruxtecan and 48% of patients treated with trastuzumab emtansine. The most commonly reported adverse event with trastuzumab deruxtecan was nausea/vomiting and fatigue. These adverse events were seen more in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. No drug-related grade 5 adverse events were reported.

In the trastuzumab deruxtecan group, 10.5% of patients receiving trastuzumab deruxtecan developed interstitial lung disease or pneumonitis. Seven patients had grade 1 events, 18 patients had grade 2 events, and 2 patients had grade 3 events. No grade 4 or 5 events were noted in either treatment group. The median time to onset of interstitial lung disease or pneumonitis in those receiving trastuzumab deruxtecan was 168 days (range, 33-507). Discontinuation of therapy due to interstitial lung disease or pneumonitis occurred in 8% of patients receiving trastuzumab deruxtecan and 1% of patients receiving trastuzumab emtansine.

Conclusion: Trastuzumab deruxtecan significantly decreases the risk of disease progression or death compared to trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on prior trastuzumab and taxane-based therapy.

Study 2 Overview (Modi et al)

Objective: To assess the efficacy of trastuzumab deruxtecan in patients with unresectable or metastatic breast cancer with low levels of HER2 expression.

Design: This was a randomized, 2-group, open-label, phase 3 trial.

Setting and participants: The trial was designed with a planned enrollment of 480 patients with hormone receptor–positive disease and 60 patients with hormone receptor–negative disease. Patients were randomized in a 2:1 ratio. Randomization was stratified according to HER2 status (immunohistochemical [IHC] 1+ vs IHC 2+/in situ hybridization [ISH] negative), number of prior lines of therapy, and hormone-receptor status. IHC scores for HER2 expression were determined through central testing. Specimens that had HER2 IHC scores of 2+ were reflexed to ISH. Specimens were considered HER2-low-expressing if they had an IHC score of 1+ or if they had an IHC score of 2+ and were ISH negative.

Eligible patients had to have received chemotherapy for metastatic disease or had disease recurrence during or within 6 months after completing adjuvant chemotherapy. Patients with hormone receptor–positive disease must have had at least 1 line of endocrine therapy. Patients were eligible if they had stable brain metastases. Patients with interstitial lung disease were excluded.

Intervention: Patients were randomized to receive trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or physician’s choice of chemotherapy (capecitabine, eribulin, gemcitabine, paclitaxel, or nab-paclitaxel).

Main outcome measures: The primary endpoint was progression-free survival in patients with hormone receptor–positive disease. Secondary endpoints were progression-free survival among all patients, overall survival in hormone receptor–positive patients, and overall survival in all patients. Additional secondary endpoints included objective response rates, duration of response, and efficacy in hormone receptor–negative patients.

Main results: A total of 373 patients were assigned to the trastuzumab deruxtecan group and 184 patients were assigned to the physician’s choice chemotherapy group; 88% of patients in each cohort were hormone receptor–positive. In the physician’s choice chemotherapy group, 51% received eribulin, 20% received capecitabine, 10% received nab-paclitaxel, 10% received gemcitabine, and 8% received paclitaxel. The demographic and baseline characteristics were similar between both cohorts. The median duration of follow-up was 18.4 months.

The median progression-free survival in the hormone receptor–positive cohort was 10.1 months in the trastuzumab deruxtecan group and 5.4 months in the physician’s choice chemotherapy group (HR, 0.51; 95% CI, 0.4-0.64). Subgroup analyses revealed a benefit across all subgroups. The median progression-free survival among patients with a HER2 IHC score of 1+ and those with a HER2 IHC score of 2+/negative ISH were identical. In patients who received a prior CDK 4/6 inhibitor, the median progression-free survival was also 10 months in the trastuzumab deruxtecan group. In those who were CDK 4/6- naïve, the progression-free survival was 11.7 months. The progression-free survival in all patients was 9.9 months in the trastuzumab deruxtecan group and 5.1 months in the physician’s choice chemotherapy group (HR, 0.46; 95% CI, 0.24-0.89).

The median overall survival in the hormone receptor–positive cohort was 23.9 months in the trastuzumab deruxtecan group compared with 17.5 months in the physician’s choice chemotherapy group (HR, 0.64; 95% CI, 0.48-0.86; P = .003). The median overall survival in the entire population was 23.4 months in the trastuzumab deruxtecan group vs 16.8 months in the physician’s choice chemotherapy group. In the hormone receptor–negative cohort, the median overall survival was 18.2 months in the trastuzumab deruxtecan group and 8.3 months in the physician’s choice chemotherapy group. Complete responses were seen in 3.6% in the trastuzumab deruxtecan group and 0.6% and the physician’s choice chemotherapy group. The median duration of response was 10.7 months in the trastuzumab deruxtecan group and 6.8 months in the physician’s choice chemotherapy group.

Incidence of serious adverse events was 27% in the trastuzumab deruxtecan group and 25% in the physician’s choice chemotherapy group. Grade 3 or higher events occurred in 52% of the trastuzumab deruxtecan group and 67% of the physician’s choice chemotherapy group. Discontinuation due to adverse events occurred in 16% in the trastuzumab deruxtecan group and 18% in the physician’s choice chemotherapy group; 14 patients in the trastuzumab deruxtecan group and 5 patients in the physician’s choice chemotherapy group had an adverse event that was associated with death. Death due to pneumonitis in the trastuzumab deruxtecan group occurred in 2 patients. Drug-related interstitial lung disease or pneumonitis occurred in 45 patients who received trastuzumab deruxtecan. The majority of these events were grade 1 and grade 2. However, 3 patients had grade 5 interstitial lung disease or pneumonitis.

Conclusion: Treatment with trastuzumab deruxtecan led to a significant improvement in progression-free survival compared to physician’s choice chemotherapy in patients with HER2-low metastatic breast cancer.

Commentary

Trastuzumab deruxtecan is an antibody drug conjugate that consists of a humanized anti-HER2 monoclonal antibody linked to a topoisomerase 1 inhibitor. This antibody drug conjugate is unique compared with prior antibody drug conjugates such as trastuzumab emtansine in that it has a high drug-to-antibody ratio (~8). Furthermore, there appears to be a unique bystander effect resulting in off-target cytotoxicity to neighboring tumor cells, enhancing the efficacy of this novel therapy. Prior studies of trastuzumab deruxtecan have shown durable activity in heavily pretreated patients with metastatic HER2-positive breast cancer.¹

HER2-positive breast cancer represents approximately 20% of breast cancer cases in women.² Historically, HER2 positivity has been defined by strong HER2 expression with IHC staining (ie, score 3+) or HER2 amplification through ISH. Conversely, HER2-negative disease has historically been defined as those with IHC scores of 0 or 1+. This group represents approximately 60% of HER2-negative metastatic breast cancer patients.³ These patients have limited targeted treatment options after progressing on primary therapy. Prior data has shown that patients with low HER2 expression represent a heterogeneous population and thus, the historic categorization of HER2 status as positive or negative may in fact not adequately characterize the proportion of patients who may derive clinical benefit from HER2-directed therapies. Nevertheless, there have been no data to date that have shown improved outcomes in low HER2 expressers with anti-HER2 therapies.

The current studies add to the rapidly growing body of literature outlining the efficacy of the novel antibody drug conjugate trastuzumab deruxtecan. The implications of the data presented in these 2 studies are immediately practice changing.

In the DESTINY-Breast03 trial, Cortéz and colleagues show that trastuzumab deruxtecan therapy significantly prolongs progression-free survival compared with trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on first-line trastuzumab and taxane-based therapy. With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in this trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer. The overall survival in this trial was immature at the time of this analysis, and thus continued follow-up to validate the results noted here are warranted.

The DESTINY-Breast04 trial by Modi et al expands the cohort of patients who benefit from trastuzumab deruxtecan profoundly. This study defines a population of patients with HER2-low metastatic breast cancer who will now be eligible for HER2-directed therapies. These data show that therapy with trastuzumab deruxtecan leads to a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy in patients with metastatic breast cancer with low expression of HER2. This benefit was seen in both the estrogen receptor–positive cohort as well as the entire population, including pre-treated triple-negative disease. Furthermore, this study does not define a threshold of HER2 expression by IHC that predicts benefit with trastuzumab deruxtecan. Patients with an IHC score of 1+ as well as those with a score of 2+/ISH negative both benefit to a similar extent from trastuzumab deruxtecan. Interestingly, in the DAISY trial, antitumor activity was noted with trastuzumab deruxtecan even in those without any detectable HER2 expression on IHC.⁴ Given the inconsistency and potential false negatives of IHC along with heterogeneous HER2 expression, further work is needed to better identify patients with low levels of HER2 expression who may benefit from this novel antibody drug conjugate. Thus, a reliable test to quantitatively assess the level of HER2 expression is needed in order to determine more accurately which patients will benefit from trastuzumab deruxtecan.

Last, trastuzumab deruxtecan has been associated with interstitial lung disease and pneumonitis. Interstitial lung disease and pneumonitis occurred in approximately 10% of patients who received trastuzumab deruxtecan in the DESTINY-Breast03 trial and about 12% of patients in the DESTINY-Breast04 trial. Most of these events were grade 1 and grade 2. Nevertheless, clinicians must be aware of this risk and monitor patients frequently for the development of pneumonitis or interstitial lung disease.

Application for Clinical Practice and System Implementation

The results of the current studies show a longer progression-free survival with trastuzumab deruxtecan in both HER2-low expressing metastatic breast cancer and HER2-positive metastatic breast cancer following taxane and trastuzumab-based therapy. These results are clearly practice changing and represent a new standard of care in these patient populations. It is incumbent upon treating oncologists to work with our pathology colleagues to assess HER2 IHC thoroughly in order to identify all potential patients who may benefit from trastuzumab deruxtecan in the metastatic setting. The continued advancement of anti-HER2 therapy will undoubtedly have a significant impact on patient outcomes going forward.

Practice Points

• With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in the DESTINY-Breast03 trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer.
• In the DESTINY-Breast04 trial, a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy was seen in patients with metastatic breast cancer with low expression of HER2, including both the estrogen receptor–positive cohort as well as the entire population, including those with pre-treated triple-negative disease.

­—Daniel Isaac, DO, MS

Study 1 Overview (Cortés et al)

Objective: To compare the efficacy and safety of trastuzumab deruxtecan with those of trastuzumab emtansine in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab and taxane.

Design: Phase 3, multicenter, open-label randomized trial conducted at 169 centers and 15 countries.

Setting and participants: Eligible patients had to have unresectable or metastatic HER2-positive breast cancer that had progressed during or after treatment with trastuzumab and a taxane or had disease that progressed within 6 months after neoadjuvant or adjuvant treatment involving trastuzumab or taxane. Patients with stable or previously treated brain metastases were eligible. Patients were not eligible for the study if they had symptomatic brain metastases, prior exposure to trastuzumab emtansine, or a history of interstitial lung disease.

Intervention: Patients were randomized in a 1-to-1 fashion to receive either trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or trastuzumab emtansine 3.6 mg/kg every 3 weeks. Patients were stratified according to hormone-receptor status, prior treatment with epratuzumab, and the presence or absence of visceral disease.

Main outcome measures: The primary endpoint of the study was progression-free survival as determined by an independent central review. Secondary endpoints included overall survival, overall response, and safety.

Main results: A total of 524 patients were enrolled in the study, with 261 patients randomized to trastuzumab deruxtecan and 263 patients randomized to trastuzumab emtansine. The demographic and baseline characteristics were similar between the 2 cohorts, and 60% of patients in both groups received prior epratuzumab therapy. Stable brain metastases were present in around 20% of patients in each group, and 70% of patients in each group had visceral disease. The median duration of follow-up was 16.2 months with trastuzumab deruxtecan and 15.3 months with trastuzumab emtansine.

The median progression-free survival was not reached in the trastuzumab deruxtecan group and was 6.8 months in the trastuzumab emtansine group (95% CI, 5.6-8.2). At 12 months the percentage of patients alive without disease progression was significantly larger in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. The hazard ratio for disease progression or death from any cause was 0.28 (95% CI, 0.22-0.37; P < .001). Subgroup analyses showed a benefit in progression-free survival with trastuzumab deruxtecan across all subgroups.

At the time of this analysis, the percentage of patients who were alive at 12 months was 94% with trastuzumab deruxtecan and 85.9% with trastuzumab emtansine. The response rates were significantly higher with trastuzumab deruxtecan compared with trastuzumab emtansine (79.7% vs 34.2%). A complete response was seen in 16% of patients in the trastuzumab deruxtecan arm, compared with 8.7% of patients in the trastuzumab emtansine group. The disease control rate (complete response, partial response, or stable disease) was higher in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group (96.6% vs 76.8%).

Serious adverse events were reported in 19% of patients in the trastuzumab deruxtecan group and 18% of patients in the trastuzumab emtansine group. Discontinuation due to adverse events was higher in the trastuzumab deruxtecan group, with 13.6% of patients discontinuing trastuzumab deruxtecan. Grade 3 or higher adverse events were seen in 52% of patients treated with trastuzumab deruxtecan and 48% of patients treated with trastuzumab emtansine. The most commonly reported adverse event with trastuzumab deruxtecan was nausea/vomiting and fatigue. These adverse events were seen more in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. No drug-related grade 5 adverse events were reported.

In the trastuzumab deruxtecan group, 10.5% of patients receiving trastuzumab deruxtecan developed interstitial lung disease or pneumonitis. Seven patients had grade 1 events, 18 patients had grade 2 events, and 2 patients had grade 3 events. No grade 4 or 5 events were noted in either treatment group. The median time to onset of interstitial lung disease or pneumonitis in those receiving trastuzumab deruxtecan was 168 days (range, 33-507). Discontinuation of therapy due to interstitial lung disease or pneumonitis occurred in 8% of patients receiving trastuzumab deruxtecan and 1% of patients receiving trastuzumab emtansine.

Conclusion: Trastuzumab deruxtecan significantly decreases the risk of disease progression or death compared to trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on prior trastuzumab and taxane-based therapy.

Study 2 Overview (Modi et al)

Objective: To assess the efficacy of trastuzumab deruxtecan in patients with unresectable or metastatic breast cancer with low levels of HER2 expression.

Design: This was a randomized, 2-group, open-label, phase 3 trial.

Setting and participants: The trial was designed with a planned enrollment of 480 patients with hormone receptor–positive disease and 60 patients with hormone receptor–negative disease. Patients were randomized in a 2:1 ratio. Randomization was stratified according to HER2 status (immunohistochemical [IHC] 1+ vs IHC 2+/in situ hybridization [ISH] negative), number of prior lines of therapy, and hormone-receptor status. IHC scores for HER2 expression were determined through central testing. Specimens that had HER2 IHC scores of 2+ were reflexed to ISH. Specimens were considered HER2-low-expressing if they had an IHC score of 1+ or if they had an IHC score of 2+ and were ISH negative.

Eligible patients had to have received chemotherapy for metastatic disease or had disease recurrence during or within 6 months after completing adjuvant chemotherapy. Patients with hormone receptor–positive disease must have had at least 1 line of endocrine therapy. Patients were eligible if they had stable brain metastases. Patients with interstitial lung disease were excluded.

Intervention: Patients were randomized to receive trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or physician’s choice of chemotherapy (capecitabine, eribulin, gemcitabine, paclitaxel, or nab-paclitaxel).

Main outcome measures: The primary endpoint was progression-free survival in patients with hormone receptor–positive disease. Secondary endpoints were progression-free survival among all patients, overall survival in hormone receptor–positive patients, and overall survival in all patients. Additional secondary endpoints included objective response rates, duration of response, and efficacy in hormone receptor–negative patients.

Main results: A total of 373 patients were assigned to the trastuzumab deruxtecan group and 184 patients were assigned to the physician’s choice chemotherapy group; 88% of patients in each cohort were hormone receptor–positive. In the physician’s choice chemotherapy group, 51% received eribulin, 20% received capecitabine, 10% received nab-paclitaxel, 10% received gemcitabine, and 8% received paclitaxel. The demographic and baseline characteristics were similar between both cohorts. The median duration of follow-up was 18.4 months.

The median progression-free survival in the hormone receptor–positive cohort was 10.1 months in the trastuzumab deruxtecan group and 5.4 months in the physician’s choice chemotherapy group (HR, 0.51; 95% CI, 0.4-0.64). Subgroup analyses revealed a benefit across all subgroups. The median progression-free survival among patients with a HER2 IHC score of 1+ and those with a HER2 IHC score of 2+/negative ISH were identical. In patients who received a prior CDK 4/6 inhibitor, the median progression-free survival was also 10 months in the trastuzumab deruxtecan group. In those who were CDK 4/6- naïve, the progression-free survival was 11.7 months. The progression-free survival in all patients was 9.9 months in the trastuzumab deruxtecan group and 5.1 months in the physician’s choice chemotherapy group (HR, 0.46; 95% CI, 0.24-0.89).

The median overall survival in the hormone receptor–positive cohort was 23.9 months in the trastuzumab deruxtecan group compared with 17.5 months in the physician’s choice chemotherapy group (HR, 0.64; 95% CI, 0.48-0.86; P = .003). The median overall survival in the entire population was 23.4 months in the trastuzumab deruxtecan group vs 16.8 months in the physician’s choice chemotherapy group. In the hormone receptor–negative cohort, the median overall survival was 18.2 months in the trastuzumab deruxtecan group and 8.3 months in the physician’s choice chemotherapy group. Complete responses were seen in 3.6% in the trastuzumab deruxtecan group and 0.6% and the physician’s choice chemotherapy group. The median duration of response was 10.7 months in the trastuzumab deruxtecan group and 6.8 months in the physician’s choice chemotherapy group.

Incidence of serious adverse events was 27% in the trastuzumab deruxtecan group and 25% in the physician’s choice chemotherapy group. Grade 3 or higher events occurred in 52% of the trastuzumab deruxtecan group and 67% of the physician’s choice chemotherapy group. Discontinuation due to adverse events occurred in 16% in the trastuzumab deruxtecan group and 18% in the physician’s choice chemotherapy group; 14 patients in the trastuzumab deruxtecan group and 5 patients in the physician’s choice chemotherapy group had an adverse event that was associated with death. Death due to pneumonitis in the trastuzumab deruxtecan group occurred in 2 patients. Drug-related interstitial lung disease or pneumonitis occurred in 45 patients who received trastuzumab deruxtecan. The majority of these events were grade 1 and grade 2. However, 3 patients had grade 5 interstitial lung disease or pneumonitis.

Conclusion: Treatment with trastuzumab deruxtecan led to a significant improvement in progression-free survival compared to physician’s choice chemotherapy in patients with HER2-low metastatic breast cancer.

Commentary

Trastuzumab deruxtecan is an antibody drug conjugate that consists of a humanized anti-HER2 monoclonal antibody linked to a topoisomerase 1 inhibitor. This antibody drug conjugate is unique compared with prior antibody drug conjugates such as trastuzumab emtansine in that it has a high drug-to-antibody ratio (~8). Furthermore, there appears to be a unique bystander effect resulting in off-target cytotoxicity to neighboring tumor cells, enhancing the efficacy of this novel therapy. Prior studies of trastuzumab deruxtecan have shown durable activity in heavily pretreated patients with metastatic HER2-positive breast cancer.¹

HER2-positive breast cancer represents approximately 20% of breast cancer cases in women.² Historically, HER2 positivity has been defined by strong HER2 expression with IHC staining (ie, score 3+) or HER2 amplification through ISH. Conversely, HER2-negative disease has historically been defined as those with IHC scores of 0 or 1+. This group represents approximately 60% of HER2-negative metastatic breast cancer patients.³ These patients have limited targeted treatment options after progressing on primary therapy. Prior data has shown that patients with low HER2 expression represent a heterogeneous population and thus, the historic categorization of HER2 status as positive or negative may in fact not adequately characterize the proportion of patients who may derive clinical benefit from HER2-directed therapies. Nevertheless, there have been no data to date that have shown improved outcomes in low HER2 expressers with anti-HER2 therapies.

The current studies add to the rapidly growing body of literature outlining the efficacy of the novel antibody drug conjugate trastuzumab deruxtecan. The implications of the data presented in these 2 studies are immediately practice changing.

In the DESTINY-Breast03 trial, Cortéz and colleagues show that trastuzumab deruxtecan therapy significantly prolongs progression-free survival compared with trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on first-line trastuzumab and taxane-based therapy. With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in this trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer. The overall survival in this trial was immature at the time of this analysis, and thus continued follow-up to validate the results noted here are warranted.

The DESTINY-Breast04 trial by Modi et al expands the cohort of patients who benefit from trastuzumab deruxtecan profoundly. This study defines a population of patients with HER2-low metastatic breast cancer who will now be eligible for HER2-directed therapies. These data show that therapy with trastuzumab deruxtecan leads to a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy in patients with metastatic breast cancer with low expression of HER2. This benefit was seen in both the estrogen receptor–positive cohort as well as the entire population, including pre-treated triple-negative disease. Furthermore, this study does not define a threshold of HER2 expression by IHC that predicts benefit with trastuzumab deruxtecan. Patients with an IHC score of 1+ as well as those with a score of 2+/ISH negative both benefit to a similar extent from trastuzumab deruxtecan. Interestingly, in the DAISY trial, antitumor activity was noted with trastuzumab deruxtecan even in those without any detectable HER2 expression on IHC.⁴ Given the inconsistency and potential false negatives of IHC along with heterogeneous HER2 expression, further work is needed to better identify patients with low levels of HER2 expression who may benefit from this novel antibody drug conjugate. Thus, a reliable test to quantitatively assess the level of HER2 expression is needed in order to determine more accurately which patients will benefit from trastuzumab deruxtecan.

Last, trastuzumab deruxtecan has been associated with interstitial lung disease and pneumonitis. Interstitial lung disease and pneumonitis occurred in approximately 10% of patients who received trastuzumab deruxtecan in the DESTINY-Breast03 trial and about 12% of patients in the DESTINY-Breast04 trial. Most of these events were grade 1 and grade 2. Nevertheless, clinicians must be aware of this risk and monitor patients frequently for the development of pneumonitis or interstitial lung disease.

Application for Clinical Practice and System Implementation

The results of the current studies show a longer progression-free survival with trastuzumab deruxtecan in both HER2-low expressing metastatic breast cancer and HER2-positive metastatic breast cancer following taxane and trastuzumab-based therapy. These results are clearly practice changing and represent a new standard of care in these patient populations. It is incumbent upon treating oncologists to work with our pathology colleagues to assess HER2 IHC thoroughly in order to identify all potential patients who may benefit from trastuzumab deruxtecan in the metastatic setting. The continued advancement of anti-HER2 therapy will undoubtedly have a significant impact on patient outcomes going forward.

Practice Points

• With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in the DESTINY-Breast03 trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer.
• In the DESTINY-Breast04 trial, a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy was seen in patients with metastatic breast cancer with low expression of HER2, including both the estrogen receptor–positive cohort as well as the entire population, including those with pre-treated triple-negative disease.

­—Daniel Isaac, DO, MS

Study 1 Overview (Cortés et al)

Objective: To compare the efficacy and safety of trastuzumab deruxtecan with those of trastuzumab emtansine in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab and taxane.

Design: Phase 3, multicenter, open-label randomized trial conducted at 169 centers and 15 countries.

Setting and participants: Eligible patients had to have unresectable or metastatic HER2-positive breast cancer that had progressed during or after treatment with trastuzumab and a taxane or had disease that progressed within 6 months after neoadjuvant or adjuvant treatment involving trastuzumab or taxane. Patients with stable or previously treated brain metastases were eligible. Patients were not eligible for the study if they had symptomatic brain metastases, prior exposure to trastuzumab emtansine, or a history of interstitial lung disease.

Intervention: Patients were randomized in a 1-to-1 fashion to receive either trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or trastuzumab emtansine 3.6 mg/kg every 3 weeks. Patients were stratified according to hormone-receptor status, prior treatment with epratuzumab, and the presence or absence of visceral disease.

Main outcome measures: The primary endpoint of the study was progression-free survival as determined by an independent central review. Secondary endpoints included overall survival, overall response, and safety.

Main results: A total of 524 patients were enrolled in the study, with 261 patients randomized to trastuzumab deruxtecan and 263 patients randomized to trastuzumab emtansine. The demographic and baseline characteristics were similar between the 2 cohorts, and 60% of patients in both groups received prior epratuzumab therapy. Stable brain metastases were present in around 20% of patients in each group, and 70% of patients in each group had visceral disease. The median duration of follow-up was 16.2 months with trastuzumab deruxtecan and 15.3 months with trastuzumab emtansine.

The median progression-free survival was not reached in the trastuzumab deruxtecan group and was 6.8 months in the trastuzumab emtansine group (95% CI, 5.6-8.2). At 12 months the percentage of patients alive without disease progression was significantly larger in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. The hazard ratio for disease progression or death from any cause was 0.28 (95% CI, 0.22-0.37; P < .001). Subgroup analyses showed a benefit in progression-free survival with trastuzumab deruxtecan across all subgroups.

At the time of this analysis, the percentage of patients who were alive at 12 months was 94% with trastuzumab deruxtecan and 85.9% with trastuzumab emtansine. The response rates were significantly higher with trastuzumab deruxtecan compared with trastuzumab emtansine (79.7% vs 34.2%). A complete response was seen in 16% of patients in the trastuzumab deruxtecan arm, compared with 8.7% of patients in the trastuzumab emtansine group. The disease control rate (complete response, partial response, or stable disease) was higher in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group (96.6% vs 76.8%).

Serious adverse events were reported in 19% of patients in the trastuzumab deruxtecan group and 18% of patients in the trastuzumab emtansine group. Discontinuation due to adverse events was higher in the trastuzumab deruxtecan group, with 13.6% of patients discontinuing trastuzumab deruxtecan. Grade 3 or higher adverse events were seen in 52% of patients treated with trastuzumab deruxtecan and 48% of patients treated with trastuzumab emtansine. The most commonly reported adverse event with trastuzumab deruxtecan was nausea/vomiting and fatigue. These adverse events were seen more in the trastuzumab deruxtecan group compared with the trastuzumab emtansine group. No drug-related grade 5 adverse events were reported.

In the trastuzumab deruxtecan group, 10.5% of patients receiving trastuzumab deruxtecan developed interstitial lung disease or pneumonitis. Seven patients had grade 1 events, 18 patients had grade 2 events, and 2 patients had grade 3 events. No grade 4 or 5 events were noted in either treatment group. The median time to onset of interstitial lung disease or pneumonitis in those receiving trastuzumab deruxtecan was 168 days (range, 33-507). Discontinuation of therapy due to interstitial lung disease or pneumonitis occurred in 8% of patients receiving trastuzumab deruxtecan and 1% of patients receiving trastuzumab emtansine.

Conclusion: Trastuzumab deruxtecan significantly decreases the risk of disease progression or death compared to trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on prior trastuzumab and taxane-based therapy.

Study 2 Overview (Modi et al)

Objective: To assess the efficacy of trastuzumab deruxtecan in patients with unresectable or metastatic breast cancer with low levels of HER2 expression.

Design: This was a randomized, 2-group, open-label, phase 3 trial.

Setting and participants: The trial was designed with a planned enrollment of 480 patients with hormone receptor–positive disease and 60 patients with hormone receptor–negative disease. Patients were randomized in a 2:1 ratio. Randomization was stratified according to HER2 status (immunohistochemical [IHC] 1+ vs IHC 2+/in situ hybridization [ISH] negative), number of prior lines of therapy, and hormone-receptor status. IHC scores for HER2 expression were determined through central testing. Specimens that had HER2 IHC scores of 2+ were reflexed to ISH. Specimens were considered HER2-low-expressing if they had an IHC score of 1+ or if they had an IHC score of 2+ and were ISH negative.

Eligible patients had to have received chemotherapy for metastatic disease or had disease recurrence during or within 6 months after completing adjuvant chemotherapy. Patients with hormone receptor–positive disease must have had at least 1 line of endocrine therapy. Patients were eligible if they had stable brain metastases. Patients with interstitial lung disease were excluded.

Intervention: Patients were randomized to receive trastuzumab deruxtecan 5.4 mg/kg every 3 weeks or physician’s choice of chemotherapy (capecitabine, eribulin, gemcitabine, paclitaxel, or nab-paclitaxel).

Main outcome measures: The primary endpoint was progression-free survival in patients with hormone receptor–positive disease. Secondary endpoints were progression-free survival among all patients, overall survival in hormone receptor–positive patients, and overall survival in all patients. Additional secondary endpoints included objective response rates, duration of response, and efficacy in hormone receptor–negative patients.

Main results: A total of 373 patients were assigned to the trastuzumab deruxtecan group and 184 patients were assigned to the physician’s choice chemotherapy group; 88% of patients in each cohort were hormone receptor–positive. In the physician’s choice chemotherapy group, 51% received eribulin, 20% received capecitabine, 10% received nab-paclitaxel, 10% received gemcitabine, and 8% received paclitaxel. The demographic and baseline characteristics were similar between both cohorts. The median duration of follow-up was 18.4 months.

The median progression-free survival in the hormone receptor–positive cohort was 10.1 months in the trastuzumab deruxtecan group and 5.4 months in the physician’s choice chemotherapy group (HR, 0.51; 95% CI, 0.4-0.64). Subgroup analyses revealed a benefit across all subgroups. The median progression-free survival among patients with a HER2 IHC score of 1+ and those with a HER2 IHC score of 2+/negative ISH were identical. In patients who received a prior CDK 4/6 inhibitor, the median progression-free survival was also 10 months in the trastuzumab deruxtecan group. In those who were CDK 4/6- naïve, the progression-free survival was 11.7 months. The progression-free survival in all patients was 9.9 months in the trastuzumab deruxtecan group and 5.1 months in the physician’s choice chemotherapy group (HR, 0.46; 95% CI, 0.24-0.89).

The median overall survival in the hormone receptor–positive cohort was 23.9 months in the trastuzumab deruxtecan group compared with 17.5 months in the physician’s choice chemotherapy group (HR, 0.64; 95% CI, 0.48-0.86; P = .003). The median overall survival in the entire population was 23.4 months in the trastuzumab deruxtecan group vs 16.8 months in the physician’s choice chemotherapy group. In the hormone receptor–negative cohort, the median overall survival was 18.2 months in the trastuzumab deruxtecan group and 8.3 months in the physician’s choice chemotherapy group. Complete responses were seen in 3.6% in the trastuzumab deruxtecan group and 0.6% and the physician’s choice chemotherapy group. The median duration of response was 10.7 months in the trastuzumab deruxtecan group and 6.8 months in the physician’s choice chemotherapy group.

Incidence of serious adverse events was 27% in the trastuzumab deruxtecan group and 25% in the physician’s choice chemotherapy group. Grade 3 or higher events occurred in 52% of the trastuzumab deruxtecan group and 67% of the physician’s choice chemotherapy group. Discontinuation due to adverse events occurred in 16% in the trastuzumab deruxtecan group and 18% in the physician’s choice chemotherapy group; 14 patients in the trastuzumab deruxtecan group and 5 patients in the physician’s choice chemotherapy group had an adverse event that was associated with death. Death due to pneumonitis in the trastuzumab deruxtecan group occurred in 2 patients. Drug-related interstitial lung disease or pneumonitis occurred in 45 patients who received trastuzumab deruxtecan. The majority of these events were grade 1 and grade 2. However, 3 patients had grade 5 interstitial lung disease or pneumonitis.

Conclusion: Treatment with trastuzumab deruxtecan led to a significant improvement in progression-free survival compared to physician’s choice chemotherapy in patients with HER2-low metastatic breast cancer.

Commentary

Trastuzumab deruxtecan is an antibody drug conjugate that consists of a humanized anti-HER2 monoclonal antibody linked to a topoisomerase 1 inhibitor. This antibody drug conjugate is unique compared with prior antibody drug conjugates such as trastuzumab emtansine in that it has a high drug-to-antibody ratio (~8). Furthermore, there appears to be a unique bystander effect resulting in off-target cytotoxicity to neighboring tumor cells, enhancing the efficacy of this novel therapy. Prior studies of trastuzumab deruxtecan have shown durable activity in heavily pretreated patients with metastatic HER2-positive breast cancer.¹

HER2-positive breast cancer represents approximately 20% of breast cancer cases in women.² Historically, HER2 positivity has been defined by strong HER2 expression with IHC staining (ie, score 3+) or HER2 amplification through ISH. Conversely, HER2-negative disease has historically been defined as those with IHC scores of 0 or 1+. This group represents approximately 60% of HER2-negative metastatic breast cancer patients.³ These patients have limited targeted treatment options after progressing on primary therapy. Prior data has shown that patients with low HER2 expression represent a heterogeneous population and thus, the historic categorization of HER2 status as positive or negative may in fact not adequately characterize the proportion of patients who may derive clinical benefit from HER2-directed therapies. Nevertheless, there have been no data to date that have shown improved outcomes in low HER2 expressers with anti-HER2 therapies.

The current studies add to the rapidly growing body of literature outlining the efficacy of the novel antibody drug conjugate trastuzumab deruxtecan. The implications of the data presented in these 2 studies are immediately practice changing.

In the DESTINY-Breast03 trial, Cortéz and colleagues show that trastuzumab deruxtecan therapy significantly prolongs progression-free survival compared with trastuzumab emtansine in patients with HER2-positive metastatic breast cancer who have progressed on first-line trastuzumab and taxane-based therapy. With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in this trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer. The overall survival in this trial was immature at the time of this analysis, and thus continued follow-up to validate the results noted here are warranted.

The DESTINY-Breast04 trial by Modi et al expands the cohort of patients who benefit from trastuzumab deruxtecan profoundly. This study defines a population of patients with HER2-low metastatic breast cancer who will now be eligible for HER2-directed therapies. These data show that therapy with trastuzumab deruxtecan leads to a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy in patients with metastatic breast cancer with low expression of HER2. This benefit was seen in both the estrogen receptor–positive cohort as well as the entire population, including pre-treated triple-negative disease. Furthermore, this study does not define a threshold of HER2 expression by IHC that predicts benefit with trastuzumab deruxtecan. Patients with an IHC score of 1+ as well as those with a score of 2+/ISH negative both benefit to a similar extent from trastuzumab deruxtecan. Interestingly, in the DAISY trial, antitumor activity was noted with trastuzumab deruxtecan even in those without any detectable HER2 expression on IHC.⁴ Given the inconsistency and potential false negatives of IHC along with heterogeneous HER2 expression, further work is needed to better identify patients with low levels of HER2 expression who may benefit from this novel antibody drug conjugate. Thus, a reliable test to quantitatively assess the level of HER2 expression is needed in order to determine more accurately which patients will benefit from trastuzumab deruxtecan.

Last, trastuzumab deruxtecan has been associated with interstitial lung disease and pneumonitis. Interstitial lung disease and pneumonitis occurred in approximately 10% of patients who received trastuzumab deruxtecan in the DESTINY-Breast03 trial and about 12% of patients in the DESTINY-Breast04 trial. Most of these events were grade 1 and grade 2. Nevertheless, clinicians must be aware of this risk and monitor patients frequently for the development of pneumonitis or interstitial lung disease.

Application for Clinical Practice and System Implementation

The results of the current studies show a longer progression-free survival with trastuzumab deruxtecan in both HER2-low expressing metastatic breast cancer and HER2-positive metastatic breast cancer following taxane and trastuzumab-based therapy. These results are clearly practice changing and represent a new standard of care in these patient populations. It is incumbent upon treating oncologists to work with our pathology colleagues to assess HER2 IHC thoroughly in order to identify all potential patients who may benefit from trastuzumab deruxtecan in the metastatic setting. The continued advancement of anti-HER2 therapy will undoubtedly have a significant impact on patient outcomes going forward.

Practice Points

• With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in the DESTINY-Breast03 trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer.
• In the DESTINY-Breast04 trial, a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy was seen in patients with metastatic breast cancer with low expression of HER2, including both the estrogen receptor–positive cohort as well as the entire population, including those with pre-treated triple-negative disease.

­—Daniel Isaac, DO, MS

Study Overview

Objective: To evaluate whether the addition of the potent androgen-receptor inhibitor (ARA) darolutamide to the standard doublet androgen-deprivation therapy (ADT) and docetaxel in metastatic, hormone-sensitive prostate cancer (mHSPC) would increase survival.

Design: A randomized, double-blind, placebo-controlled, multicenter, phase 3 study. The results reported in this publication are from the prespecified interim analysis.

Intervention: Patients with mHSPC were randomly assigned to receive either darolutamide 600 mg twice daily or placebo. All patients received standard ADT with 6 cycles of docetaxel 75 mg/m² on day 1 every 21 days along with prednisone given within 6 weeks after randomization. Patients receiving luteinizing hormone–releasing hormone (LHRH) agonists as ADT were bridged with at least 4 weeks of first-generation antiandrogen therapy, which was discontinued before randomization. Treatments were continued until symptomatic disease progression, a change in neoplastic therapy, unacceptable toxicity, patient or physician decision, death, or nonadherence.

Setting and participants: Eligible patients included those newly diagnosed with mHSPC with metastases detected on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) and bone scan. Patients were excluded if they had regional lymph node–only involvement or if they had received more than 12 weeks of ADT before randomization. Between November 2016 and June 2018, 1306 patients (651 in the darolutamide group and 655 in the placebo group) were randomized in a 1:1 manner to receive darolutamide 600 mg twice daily or placebo in addition to ADT and docetaxel. Randomization was stratified based on the TNM staging system (M1a—nonregional lymph node–only metastasis, M1b—bone metastasis with or without lymph node, or M1c—bone metastases) as well as baseline alkaline phosphatase levels.

Main outcome measures: The primary end point for the study was overall survival. Other meaningful secondary end points included time to castration resistance, time to pain progression, time to first symptomatic skeletal event, symptomatic skeletal event-free survival, time to subsequent systemic antineoplastic therapy, time to worsening of disease-related physical symptoms, initiation of opioid therapy for ≥7 days, and safety.

Results: The baseline and demographic characteristics were well balanced between the 2 groups. Median age was 67 years. Nearly 80% of patients had bone metastasis, and approximately 17% had visceral metastasis. At the data cutoff date for the primary analysis, the median duration of therapy was 41 months for darolutamide compared with 16.7 months in the placebo group; 45.9% in the darolutamide group and 19.1% in the placebo group were receiving the allotted trial therapy at the time of the analysis. Six cycles of docetaxel were completed in approximately 85% of patients in both arms. Median overall survival follow-up was 43.7 months (darolutamide) and 42.4 months (placebo). A significant improvement in overall survival was observed in the darolutamide group. The risk of death was 32.5% lower in the darolutamide cohort than in the placebo cohort (hazard ratio [HR], 0.68; 95% CI, 0.57-0.80; P < .001). The overall survival at 4 years was 62.7% (95% CI, 58.7-66.7) in the darolutamide arm and 50.4% (95% CI, 46.3-54.6) in the placebo arm. The overall survival results remained favorable across most subgroups.

Darolutamide was associated with improvement in all key secondary endpoints. Time to castration-resistance was significantly longer in the darolutamide group (HR, 0.36; 95% CI, 0.30-0.42; P < .001). Time to pain progression was also significantly longer in the darolutamide group (HR, 0.79; 95% CI, 0.66-0.95; P = .01). Time to first symptomatic skeletal events (HR, 0.71; 95% CI, 0.54-0.94; P = .02) and time to initiation of subsequent systemic therapy (HR, 0.39; 95% CI, 0.33-0.46; P < .001) were also found to be longer in the darolutamide group.

Safety: The risk of grade 3 or higher adverse events was similar across the 2 groups. Most common adverse events were known toxic effects of docetaxel therapy and were highest during the initial period when both groups received this therapy. These side effects progressively decreased after the initial period. The most common grade 3 or 4 adverse event was neutropenia, and its frequency was similar between the darolutamide and placebo groups (33.7% and 34.2%, respectively). The most frequently reported adverse events were alopecia, neutropenia, fatigue, and anemia and were similar between the groups. Adverse events of special significance, including fatigue, falls, fractures, and cardiovascular events, were also similar between the 2 groups. Adverse events causing deaths in each arm were low and similar (4.1% in the darolutamide group and 4.0% in the placebo group). The rates of discontinuation of darolutamide or placebo were similar (13.5% and 10.6%, respectively).

Conclusion: Among patients with mHSPC, overall survival was significantly longer among patients who received darolutamide plus ADT and docetaxel than among those who received ADT and docetaxel alone. This was observed despite a high percentage of patients in the placebo group receiving subsequent systemic therapy at the time of progression. The survival benefit of darolutamide was maintained across most subgroups. An improvement was also observed in the darolutamide arm in terms of key secondary end points. The adverse events were similar across the groups and were consistent with known safety profiles of ADT and docetaxel, and no new safety signals were identified in this trial.

Commentary

The results of the current study add to the body of literature supporting multi-agent systemic therapy in newly diagnosed mHSPC. Prior phase 3 trials of combination therapy using androgen-receptor pathway inhibitors, ADT, and docetaxel have shown conflicting results. The results from the previously reported PEACE-1 study showed improved overall survival among patients who received abiraterone with ADT and docetaxel as compared with those who received ADT and docetaxel alone.¹ However, as noted by the authors, the subgroup of patients in the ENZAMET trial who received docetaxel, enzalutamide, and ADT did not appear to have a survival advantage compared with those who received ADT and docetaxel alone.² The results from the current ARASENS trial provide compelling evidence in a population of prospectively randomized patients that combination therapy with darolutamide, docetaxel, and ADT improves overall survival in men with mHSPC. The survival advantage was maintained across subgroups analyzed in this study. Improvements were observed in regards to several key secondary end points with use of darolutamide. This benefit was maintained despite many patients receiving subsequent therapy at the time of progression. Importantly, there did not appear to be a significant increase in toxicity with triplet therapy. However, it is important to note that this cohort of patients appeared largely asymptomatic at the time of enrollment, with 70% of patients having an Eastern Cooperative Oncology Group performance status of 0.

Additionally, the average age in this study was 67 years, with only about 15% of the population being older than 75 years. In the reported subgroup analysis, those older than 75 years appeared to derive a similar benefit in overall survival, however. Whether triplet therapy should be universally adopted in all patients remains unclear. For example, there is a subset of patients with mHSPC with favorable- risk disease (ie, those with recurrent metastatic disease, node-only disease). In this population, the risk-benefit analysis is less clear, and whether these patients should receive this combination is not certain. Nevertheless, the results of this well-designed study are compelling and certainly represent a potential new standard treatment option for men with mHSPC. One of the strengths of this study was its large sample size that allowed for vigorous statistical analysis to evaluate the efficacy of darolutamide in combination with ADT and docetaxel.

Application for Clinical Practice

The ARASENS study provides convincing evidence that in men with mHSPC, the addition of darolutamide to docetaxel and ADT improves overall survival. This combination appeared to be well tolerated, with no evidence of increased toxicity noted. Certainly, this combination represents a potential new standard treatment option in this population; however, further understanding of which subgroups of men benefit from enhanced therapy is needed to aid in proper patient selection. 

—Santosh Kagathur, MD, and Daniel Isaac, DO, MS
Michigan State University, East Lansing, MI

Study Overview

Objective: To evaluate whether the addition of the potent androgen-receptor inhibitor (ARA) darolutamide to the standard doublet androgen-deprivation therapy (ADT) and docetaxel in metastatic, hormone-sensitive prostate cancer (mHSPC) would increase survival.

Design: A randomized, double-blind, placebo-controlled, multicenter, phase 3 study. The results reported in this publication are from the prespecified interim analysis.

Intervention: Patients with mHSPC were randomly assigned to receive either darolutamide 600 mg twice daily or placebo. All patients received standard ADT with 6 cycles of docetaxel 75 mg/m² on day 1 every 21 days along with prednisone given within 6 weeks after randomization. Patients receiving luteinizing hormone–releasing hormone (LHRH) agonists as ADT were bridged with at least 4 weeks of first-generation antiandrogen therapy, which was discontinued before randomization. Treatments were continued until symptomatic disease progression, a change in neoplastic therapy, unacceptable toxicity, patient or physician decision, death, or nonadherence.

Setting and participants: Eligible patients included those newly diagnosed with mHSPC with metastases detected on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) and bone scan. Patients were excluded if they had regional lymph node–only involvement or if they had received more than 12 weeks of ADT before randomization. Between November 2016 and June 2018, 1306 patients (651 in the darolutamide group and 655 in the placebo group) were randomized in a 1:1 manner to receive darolutamide 600 mg twice daily or placebo in addition to ADT and docetaxel. Randomization was stratified based on the TNM staging system (M1a—nonregional lymph node–only metastasis, M1b—bone metastasis with or without lymph node, or M1c—bone metastases) as well as baseline alkaline phosphatase levels.

Main outcome measures: The primary end point for the study was overall survival. Other meaningful secondary end points included time to castration resistance, time to pain progression, time to first symptomatic skeletal event, symptomatic skeletal event-free survival, time to subsequent systemic antineoplastic therapy, time to worsening of disease-related physical symptoms, initiation of opioid therapy for ≥7 days, and safety.

Results: The baseline and demographic characteristics were well balanced between the 2 groups. Median age was 67 years. Nearly 80% of patients had bone metastasis, and approximately 17% had visceral metastasis. At the data cutoff date for the primary analysis, the median duration of therapy was 41 months for darolutamide compared with 16.7 months in the placebo group; 45.9% in the darolutamide group and 19.1% in the placebo group were receiving the allotted trial therapy at the time of the analysis. Six cycles of docetaxel were completed in approximately 85% of patients in both arms. Median overall survival follow-up was 43.7 months (darolutamide) and 42.4 months (placebo). A significant improvement in overall survival was observed in the darolutamide group. The risk of death was 32.5% lower in the darolutamide cohort than in the placebo cohort (hazard ratio [HR], 0.68; 95% CI, 0.57-0.80; P < .001). The overall survival at 4 years was 62.7% (95% CI, 58.7-66.7) in the darolutamide arm and 50.4% (95% CI, 46.3-54.6) in the placebo arm. The overall survival results remained favorable across most subgroups.

Darolutamide was associated with improvement in all key secondary endpoints. Time to castration-resistance was significantly longer in the darolutamide group (HR, 0.36; 95% CI, 0.30-0.42; P < .001). Time to pain progression was also significantly longer in the darolutamide group (HR, 0.79; 95% CI, 0.66-0.95; P = .01). Time to first symptomatic skeletal events (HR, 0.71; 95% CI, 0.54-0.94; P = .02) and time to initiation of subsequent systemic therapy (HR, 0.39; 95% CI, 0.33-0.46; P < .001) were also found to be longer in the darolutamide group.

Safety: The risk of grade 3 or higher adverse events was similar across the 2 groups. Most common adverse events were known toxic effects of docetaxel therapy and were highest during the initial period when both groups received this therapy. These side effects progressively decreased after the initial period. The most common grade 3 or 4 adverse event was neutropenia, and its frequency was similar between the darolutamide and placebo groups (33.7% and 34.2%, respectively). The most frequently reported adverse events were alopecia, neutropenia, fatigue, and anemia and were similar between the groups. Adverse events of special significance, including fatigue, falls, fractures, and cardiovascular events, were also similar between the 2 groups. Adverse events causing deaths in each arm were low and similar (4.1% in the darolutamide group and 4.0% in the placebo group). The rates of discontinuation of darolutamide or placebo were similar (13.5% and 10.6%, respectively).

Conclusion: Among patients with mHSPC, overall survival was significantly longer among patients who received darolutamide plus ADT and docetaxel than among those who received ADT and docetaxel alone. This was observed despite a high percentage of patients in the placebo group receiving subsequent systemic therapy at the time of progression. The survival benefit of darolutamide was maintained across most subgroups. An improvement was also observed in the darolutamide arm in terms of key secondary end points. The adverse events were similar across the groups and were consistent with known safety profiles of ADT and docetaxel, and no new safety signals were identified in this trial.

Commentary

The results of the current study add to the body of literature supporting multi-agent systemic therapy in newly diagnosed mHSPC. Prior phase 3 trials of combination therapy using androgen-receptor pathway inhibitors, ADT, and docetaxel have shown conflicting results. The results from the previously reported PEACE-1 study showed improved overall survival among patients who received abiraterone with ADT and docetaxel as compared with those who received ADT and docetaxel alone.¹ However, as noted by the authors, the subgroup of patients in the ENZAMET trial who received docetaxel, enzalutamide, and ADT did not appear to have a survival advantage compared with those who received ADT and docetaxel alone.² The results from the current ARASENS trial provide compelling evidence in a population of prospectively randomized patients that combination therapy with darolutamide, docetaxel, and ADT improves overall survival in men with mHSPC. The survival advantage was maintained across subgroups analyzed in this study. Improvements were observed in regards to several key secondary end points with use of darolutamide. This benefit was maintained despite many patients receiving subsequent therapy at the time of progression. Importantly, there did not appear to be a significant increase in toxicity with triplet therapy. However, it is important to note that this cohort of patients appeared largely asymptomatic at the time of enrollment, with 70% of patients having an Eastern Cooperative Oncology Group performance status of 0.

Additionally, the average age in this study was 67 years, with only about 15% of the population being older than 75 years. In the reported subgroup analysis, those older than 75 years appeared to derive a similar benefit in overall survival, however. Whether triplet therapy should be universally adopted in all patients remains unclear. For example, there is a subset of patients with mHSPC with favorable- risk disease (ie, those with recurrent metastatic disease, node-only disease). In this population, the risk-benefit analysis is less clear, and whether these patients should receive this combination is not certain. Nevertheless, the results of this well-designed study are compelling and certainly represent a potential new standard treatment option for men with mHSPC. One of the strengths of this study was its large sample size that allowed for vigorous statistical analysis to evaluate the efficacy of darolutamide in combination with ADT and docetaxel.

Application for Clinical Practice

The ARASENS study provides convincing evidence that in men with mHSPC, the addition of darolutamide to docetaxel and ADT improves overall survival. This combination appeared to be well tolerated, with no evidence of increased toxicity noted. Certainly, this combination represents a potential new standard treatment option in this population; however, further understanding of which subgroups of men benefit from enhanced therapy is needed to aid in proper patient selection. 

—Santosh Kagathur, MD, and Daniel Isaac, DO, MS
Michigan State University, East Lansing, MI

Study Overview

Objective: To evaluate whether the addition of the potent androgen-receptor inhibitor (ARA) darolutamide to the standard doublet androgen-deprivation therapy (ADT) and docetaxel in metastatic, hormone-sensitive prostate cancer (mHSPC) would increase survival.

Design: A randomized, double-blind, placebo-controlled, multicenter, phase 3 study. The results reported in this publication are from the prespecified interim analysis.

Intervention: Patients with mHSPC were randomly assigned to receive either darolutamide 600 mg twice daily or placebo. All patients received standard ADT with 6 cycles of docetaxel 75 mg/m² on day 1 every 21 days along with prednisone given within 6 weeks after randomization. Patients receiving luteinizing hormone–releasing hormone (LHRH) agonists as ADT were bridged with at least 4 weeks of first-generation antiandrogen therapy, which was discontinued before randomization. Treatments were continued until symptomatic disease progression, a change in neoplastic therapy, unacceptable toxicity, patient or physician decision, death, or nonadherence.

Setting and participants: Eligible patients included those newly diagnosed with mHSPC with metastases detected on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) and bone scan. Patients were excluded if they had regional lymph node–only involvement or if they had received more than 12 weeks of ADT before randomization. Between November 2016 and June 2018, 1306 patients (651 in the darolutamide group and 655 in the placebo group) were randomized in a 1:1 manner to receive darolutamide 600 mg twice daily or placebo in addition to ADT and docetaxel. Randomization was stratified based on the TNM staging system (M1a—nonregional lymph node–only metastasis, M1b—bone metastasis with or without lymph node, or M1c—bone metastases) as well as baseline alkaline phosphatase levels.

Main outcome measures: The primary end point for the study was overall survival. Other meaningful secondary end points included time to castration resistance, time to pain progression, time to first symptomatic skeletal event, symptomatic skeletal event-free survival, time to subsequent systemic antineoplastic therapy, time to worsening of disease-related physical symptoms, initiation of opioid therapy for ≥7 days, and safety.

Results: The baseline and demographic characteristics were well balanced between the 2 groups. Median age was 67 years. Nearly 80% of patients had bone metastasis, and approximately 17% had visceral metastasis. At the data cutoff date for the primary analysis, the median duration of therapy was 41 months for darolutamide compared with 16.7 months in the placebo group; 45.9% in the darolutamide group and 19.1% in the placebo group were receiving the allotted trial therapy at the time of the analysis. Six cycles of docetaxel were completed in approximately 85% of patients in both arms. Median overall survival follow-up was 43.7 months (darolutamide) and 42.4 months (placebo). A significant improvement in overall survival was observed in the darolutamide group. The risk of death was 32.5% lower in the darolutamide cohort than in the placebo cohort (hazard ratio [HR], 0.68; 95% CI, 0.57-0.80; P < .001). The overall survival at 4 years was 62.7% (95% CI, 58.7-66.7) in the darolutamide arm and 50.4% (95% CI, 46.3-54.6) in the placebo arm. The overall survival results remained favorable across most subgroups.

Darolutamide was associated with improvement in all key secondary endpoints. Time to castration-resistance was significantly longer in the darolutamide group (HR, 0.36; 95% CI, 0.30-0.42; P < .001). Time to pain progression was also significantly longer in the darolutamide group (HR, 0.79; 95% CI, 0.66-0.95; P = .01). Time to first symptomatic skeletal events (HR, 0.71; 95% CI, 0.54-0.94; P = .02) and time to initiation of subsequent systemic therapy (HR, 0.39; 95% CI, 0.33-0.46; P < .001) were also found to be longer in the darolutamide group.

Safety: The risk of grade 3 or higher adverse events was similar across the 2 groups. Most common adverse events were known toxic effects of docetaxel therapy and were highest during the initial period when both groups received this therapy. These side effects progressively decreased after the initial period. The most common grade 3 or 4 adverse event was neutropenia, and its frequency was similar between the darolutamide and placebo groups (33.7% and 34.2%, respectively). The most frequently reported adverse events were alopecia, neutropenia, fatigue, and anemia and were similar between the groups. Adverse events of special significance, including fatigue, falls, fractures, and cardiovascular events, were also similar between the 2 groups. Adverse events causing deaths in each arm were low and similar (4.1% in the darolutamide group and 4.0% in the placebo group). The rates of discontinuation of darolutamide or placebo were similar (13.5% and 10.6%, respectively).

Conclusion: Among patients with mHSPC, overall survival was significantly longer among patients who received darolutamide plus ADT and docetaxel than among those who received ADT and docetaxel alone. This was observed despite a high percentage of patients in the placebo group receiving subsequent systemic therapy at the time of progression. The survival benefit of darolutamide was maintained across most subgroups. An improvement was also observed in the darolutamide arm in terms of key secondary end points. The adverse events were similar across the groups and were consistent with known safety profiles of ADT and docetaxel, and no new safety signals were identified in this trial.

Commentary

The results of the current study add to the body of literature supporting multi-agent systemic therapy in newly diagnosed mHSPC. Prior phase 3 trials of combination therapy using androgen-receptor pathway inhibitors, ADT, and docetaxel have shown conflicting results. The results from the previously reported PEACE-1 study showed improved overall survival among patients who received abiraterone with ADT and docetaxel as compared with those who received ADT and docetaxel alone.¹ However, as noted by the authors, the subgroup of patients in the ENZAMET trial who received docetaxel, enzalutamide, and ADT did not appear to have a survival advantage compared with those who received ADT and docetaxel alone.² The results from the current ARASENS trial provide compelling evidence in a population of prospectively randomized patients that combination therapy with darolutamide, docetaxel, and ADT improves overall survival in men with mHSPC. The survival advantage was maintained across subgroups analyzed in this study. Improvements were observed in regards to several key secondary end points with use of darolutamide. This benefit was maintained despite many patients receiving subsequent therapy at the time of progression. Importantly, there did not appear to be a significant increase in toxicity with triplet therapy. However, it is important to note that this cohort of patients appeared largely asymptomatic at the time of enrollment, with 70% of patients having an Eastern Cooperative Oncology Group performance status of 0.

Additionally, the average age in this study was 67 years, with only about 15% of the population being older than 75 years. In the reported subgroup analysis, those older than 75 years appeared to derive a similar benefit in overall survival, however. Whether triplet therapy should be universally adopted in all patients remains unclear. For example, there is a subset of patients with mHSPC with favorable- risk disease (ie, those with recurrent metastatic disease, node-only disease). In this population, the risk-benefit analysis is less clear, and whether these patients should receive this combination is not certain. Nevertheless, the results of this well-designed study are compelling and certainly represent a potential new standard treatment option for men with mHSPC. One of the strengths of this study was its large sample size that allowed for vigorous statistical analysis to evaluate the efficacy of darolutamide in combination with ADT and docetaxel.

Application for Clinical Practice

The ARASENS study provides convincing evidence that in men with mHSPC, the addition of darolutamide to docetaxel and ADT improves overall survival. This combination appeared to be well tolerated, with no evidence of increased toxicity noted. Certainly, this combination represents a potential new standard treatment option in this population; however, further understanding of which subgroups of men benefit from enhanced therapy is needed to aid in proper patient selection. 

—Santosh Kagathur, MD, and Daniel Isaac, DO, MS
Michigan State University, East Lansing, MI

Study Overview

Objective. To assess the efficacy and safety of olaparib as an adjuvant treatment in patients with BRCA1 or BRCA2 germline mutations who are at a high-risk for relapse.

Design. A randomized, double-blind, placebo-controlled, multicenter phase III study. The published results are from the prespecified interim analysis.

Intervention. Patients were randomized in 1:1 ratio to either receive 300 mg of olaparib orally twice daily or to receive a matching placebo. Randomization was stratified by hormone receptor status (estrogen receptor and/or progesterone receptor positive/HER2-negative vs triple negative), prior neoadjuvant vs adjuvant chemotherapy, and prior platinum use for breast cancer. Treatment was continued for 52 weeks.

Setting and participants. A total of 1836 patients were randomized in a 1:1 fashion to receive olaparib or a placebo. Eligible patients had a germline BRCA1 or BRCA1 pathogenic or likely pathogenic variant. Patients had high-risk, HER2-negative primary breast cancers and all had received definitive local therapy and neoadjuvant or adjuvant chemotherapy. Patients were enrolled between 2 to 12 weeks after completion of all local therapy. Platinum chemotherapy was allowed. Patients received adjuvant endocrine therapy for hormone receptor positive disease as well as adjuvant bisphosphonates per institutional guidelines. Patients with triple negative disease who received adjuvant chemotherapy were required to be lymph node positive or have at least 2 cm invasive disease. Patients who received neoadjuvant chemotherapy were required to have residual invasive disease to be eligible. For hormone receptor positive patients receiving adjuvant chemotherapy to be eligible they had to have at least 4 pathologically confirmed lymph nodes involved. Hormone receptor positive patients who had neoadjuvant chemotherapy were required to have had residual invasive disease.

Main outcome measures. The primary endpoint for the study was invasive disease-free survival which was defined as time from randomization to date of recurrence or death from any cause. The secondary endpoints included overall survival (OS), distant disease-free survival, safety, and tolerability of olaparib.

Main results. At the time of data cutoff, 284 events had occurred with a median follow-up of 2.5 years in the intention to treat population. A total of 81% of patients had triple negative breast cancer. Most patients (94% in the olaparib group and 92% in the placebo group) received both taxane and anthracycline based chemotherapy regimens. Platinum based chemotherapy was used in 26% of patients in each group. The groups were otherwise well balanced. Germline mutations in BRCA1 were present in 72% of patients and BRCA2 in 27% of patients. These were balanced between groups.

At the time of this analysis, adjuvant olaparib reduced the risk of invasive disease-free survival by 42% compared with placebo (P < .001). At 3 years, invasive disease-free survival was 85.9% in the olaparib group and 77.1% in the placebo group (difference, 8.8 percentage points; 95% CI, 4.5-13.0; hazard ratio [HR], 0.58; 99.5% CI, 0.41-0.82; P < .001). The 3-year distant disease-free survival was 87.5% in the olaparib group and 80.4% in the placebo group (HR 0.57; 99.5% CI, 0.39-0.83; P < .001). Results also showed that olaparib was associated with fewer deaths than placebo (59 and 86, respectively) (HR, 0.68; 99% CI, 0.44-1.05; P = .02); however, there was no significant difference between treatment arms at the time of this interim analysis. Subgroup analysis showed a consistent benefit across all groups with no difference noted regarding BRCA mutation, hormone receptor status or use of neoadjuvant vs adjuvant chemotherapy.

The side effects were consistent with the safety profile of olaparib. Adverse events of grade 3 or higher more common with olaparib included anemia (8.7%), leukopenia (3%), and fatigue (1.8%). Early discontinuation of trial regimen due to adverse events of disease recurrence occurred in 25.9% in the olaparib group and 20.7% in the placebo group. Blood transfusions were required in 5.8% of patients in the olaparib group. Myelodysplasia or acute myleoid leukemia was observed in 2 patients in the olaparib group and 3 patients in the placebo group. Adverse events leading to death occurred in 1 patient in the olaparib group and 2 patients in the placebo group.

Conclusion. Among patients with high-risk, HER2-negative early breast cancer and germline BRCA1 or BRCA2 pathogenic or likely pathogenic variants, adjuvant olaparib after completion of local treatment and neoadjuvant or adjuvant chemotherapy was associated with significantly longer invasive disease-free and distant disease-free survival compared with placebo.

Commentary

The results from the current OlympiA trial provide the first evidence that adjuvant therapy with poly adenosine diphosphate-ribose polymerase (PARP) inhibitors can improve outcomes in high-risk, HER2-negative breast cancer in patients with pathogenic BRCA1 and BRCA2 mutations. The OS, while favoring olaparib, is not yet mature at the time of this analysis. Nevertheless, these results represent an important step forward in improving outcomes in this patient population. The efficacy and safety of PARP inhibitors in BRCA-mutated breast cancer has previously been shown in patients with advanced disease leading to FDA approval of both olaparib and talazoparib in this setting.^1,2 With the current results, PARP inhibitors will certainly play an important role in the adjuvant setting in patients with deleterious BRCA1 or BRCA2 mutations at high risk for relapse. Importantly, the side effect profile appears acceptable with no unexpected events and a very low rate of secondary myeloid malignancies.

Subgroup analysis appears to indicate a benefit across all groups including hormone receptor–positive disease and triple negative breast cancer. Interestingly, approximately 25% of patients in both cohorts received platinum-based chemotherapy. The efficacy of adjuvant olaparib did not appear to be impacted by prior use of platinum-containing chemotherapy regimens. It is important to consider that postneoadjuvant capecitabine, per the results of the CREATE-X trial, in triple-negative patients was not permitted in the current study. Although, this has been widely adopted in clinical practice.³ The CREATE-X trial did not specify the benefit of adjuvant capecitabine in the BRCA-mutated cohort, thus, it is not clear how this subgroup fares with this approach. Thus, one cannot extrapolate the relative efficacy of olaparib compared with capecitabine, as pointed out by the authors, and whether we consider the use of capecitabine and/or olaparib in triple-negative patients with residual invasive disease after neoadjuvant chemotherapy is not clear at this time.

Nevertheless, the magnitude of benefit seen in this trial certainly provide clinically relevant and potentially practice changing results. It will be imperative to follow these results as the survival data matures and ensure no further long-term toxicity, particularly secondary myeloid malignancies, develop. These results should be discussed with each patient and informed decisions regarding the use of adjuvant olaparib should be considered for this patient population. Lastly, these results highlight the importance of germline testing for patients with breast cancer in accordance with national guideline recommendations. Moreover, these results certainly call into question whether it is time to consider expansion of our current germline testing guidelines to detect all potential patients who may benefit from this therapy.

Application for Clinical Practice

Adjuvant olaparib in high-risk patients with germline BRCA1 or BRCA2 mutations improves invasive and distant disease-free survival and should be considered in patients who meet the enrollment criteria of the current study. Furthermore, this highlights the importance of appropriate germline genetic testing in patients with breast cancer.

Financial disclosures: None.

Study Overview

Objective. To assess the efficacy and safety of olaparib as an adjuvant treatment in patients with BRCA1 or BRCA2 germline mutations who are at a high-risk for relapse.

Design. A randomized, double-blind, placebo-controlled, multicenter phase III study. The published results are from the prespecified interim analysis.

Intervention. Patients were randomized in 1:1 ratio to either receive 300 mg of olaparib orally twice daily or to receive a matching placebo. Randomization was stratified by hormone receptor status (estrogen receptor and/or progesterone receptor positive/HER2-negative vs triple negative), prior neoadjuvant vs adjuvant chemotherapy, and prior platinum use for breast cancer. Treatment was continued for 52 weeks.

Setting and participants. A total of 1836 patients were randomized in a 1:1 fashion to receive olaparib or a placebo. Eligible patients had a germline BRCA1 or BRCA1 pathogenic or likely pathogenic variant. Patients had high-risk, HER2-negative primary breast cancers and all had received definitive local therapy and neoadjuvant or adjuvant chemotherapy. Patients were enrolled between 2 to 12 weeks after completion of all local therapy. Platinum chemotherapy was allowed. Patients received adjuvant endocrine therapy for hormone receptor positive disease as well as adjuvant bisphosphonates per institutional guidelines. Patients with triple negative disease who received adjuvant chemotherapy were required to be lymph node positive or have at least 2 cm invasive disease. Patients who received neoadjuvant chemotherapy were required to have residual invasive disease to be eligible. For hormone receptor positive patients receiving adjuvant chemotherapy to be eligible they had to have at least 4 pathologically confirmed lymph nodes involved. Hormone receptor positive patients who had neoadjuvant chemotherapy were required to have had residual invasive disease.

Main outcome measures. The primary endpoint for the study was invasive disease-free survival which was defined as time from randomization to date of recurrence or death from any cause. The secondary endpoints included overall survival (OS), distant disease-free survival, safety, and tolerability of olaparib.

Main results. At the time of data cutoff, 284 events had occurred with a median follow-up of 2.5 years in the intention to treat population. A total of 81% of patients had triple negative breast cancer. Most patients (94% in the olaparib group and 92% in the placebo group) received both taxane and anthracycline based chemotherapy regimens. Platinum based chemotherapy was used in 26% of patients in each group. The groups were otherwise well balanced. Germline mutations in BRCA1 were present in 72% of patients and BRCA2 in 27% of patients. These were balanced between groups.

At the time of this analysis, adjuvant olaparib reduced the risk of invasive disease-free survival by 42% compared with placebo (P < .001). At 3 years, invasive disease-free survival was 85.9% in the olaparib group and 77.1% in the placebo group (difference, 8.8 percentage points; 95% CI, 4.5-13.0; hazard ratio [HR], 0.58; 99.5% CI, 0.41-0.82; P < .001). The 3-year distant disease-free survival was 87.5% in the olaparib group and 80.4% in the placebo group (HR 0.57; 99.5% CI, 0.39-0.83; P < .001). Results also showed that olaparib was associated with fewer deaths than placebo (59 and 86, respectively) (HR, 0.68; 99% CI, 0.44-1.05; P = .02); however, there was no significant difference between treatment arms at the time of this interim analysis. Subgroup analysis showed a consistent benefit across all groups with no difference noted regarding BRCA mutation, hormone receptor status or use of neoadjuvant vs adjuvant chemotherapy.

The side effects were consistent with the safety profile of olaparib. Adverse events of grade 3 or higher more common with olaparib included anemia (8.7%), leukopenia (3%), and fatigue (1.8%). Early discontinuation of trial regimen due to adverse events of disease recurrence occurred in 25.9% in the olaparib group and 20.7% in the placebo group. Blood transfusions were required in 5.8% of patients in the olaparib group. Myelodysplasia or acute myleoid leukemia was observed in 2 patients in the olaparib group and 3 patients in the placebo group. Adverse events leading to death occurred in 1 patient in the olaparib group and 2 patients in the placebo group.

Conclusion. Among patients with high-risk, HER2-negative early breast cancer and germline BRCA1 or BRCA2 pathogenic or likely pathogenic variants, adjuvant olaparib after completion of local treatment and neoadjuvant or adjuvant chemotherapy was associated with significantly longer invasive disease-free and distant disease-free survival compared with placebo.

Commentary

The results from the current OlympiA trial provide the first evidence that adjuvant therapy with poly adenosine diphosphate-ribose polymerase (PARP) inhibitors can improve outcomes in high-risk, HER2-negative breast cancer in patients with pathogenic BRCA1 and BRCA2 mutations. The OS, while favoring olaparib, is not yet mature at the time of this analysis. Nevertheless, these results represent an important step forward in improving outcomes in this patient population. The efficacy and safety of PARP inhibitors in BRCA-mutated breast cancer has previously been shown in patients with advanced disease leading to FDA approval of both olaparib and talazoparib in this setting.^1,2 With the current results, PARP inhibitors will certainly play an important role in the adjuvant setting in patients with deleterious BRCA1 or BRCA2 mutations at high risk for relapse. Importantly, the side effect profile appears acceptable with no unexpected events and a very low rate of secondary myeloid malignancies.

Subgroup analysis appears to indicate a benefit across all groups including hormone receptor–positive disease and triple negative breast cancer. Interestingly, approximately 25% of patients in both cohorts received platinum-based chemotherapy. The efficacy of adjuvant olaparib did not appear to be impacted by prior use of platinum-containing chemotherapy regimens. It is important to consider that postneoadjuvant capecitabine, per the results of the CREATE-X trial, in triple-negative patients was not permitted in the current study. Although, this has been widely adopted in clinical practice.³ The CREATE-X trial did not specify the benefit of adjuvant capecitabine in the BRCA-mutated cohort, thus, it is not clear how this subgroup fares with this approach. Thus, one cannot extrapolate the relative efficacy of olaparib compared with capecitabine, as pointed out by the authors, and whether we consider the use of capecitabine and/or olaparib in triple-negative patients with residual invasive disease after neoadjuvant chemotherapy is not clear at this time.

Nevertheless, the magnitude of benefit seen in this trial certainly provide clinically relevant and potentially practice changing results. It will be imperative to follow these results as the survival data matures and ensure no further long-term toxicity, particularly secondary myeloid malignancies, develop. These results should be discussed with each patient and informed decisions regarding the use of adjuvant olaparib should be considered for this patient population. Lastly, these results highlight the importance of germline testing for patients with breast cancer in accordance with national guideline recommendations. Moreover, these results certainly call into question whether it is time to consider expansion of our current germline testing guidelines to detect all potential patients who may benefit from this therapy.

Application for Clinical Practice

Adjuvant olaparib in high-risk patients with germline BRCA1 or BRCA2 mutations improves invasive and distant disease-free survival and should be considered in patients who meet the enrollment criteria of the current study. Furthermore, this highlights the importance of appropriate germline genetic testing in patients with breast cancer.

Financial disclosures: None.

Study Overview

Objective. To assess the efficacy and safety of olaparib as an adjuvant treatment in patients with BRCA1 or BRCA2 germline mutations who are at a high-risk for relapse.

Design. A randomized, double-blind, placebo-controlled, multicenter phase III study. The published results are from the prespecified interim analysis.

Intervention. Patients were randomized in 1:1 ratio to either receive 300 mg of olaparib orally twice daily or to receive a matching placebo. Randomization was stratified by hormone receptor status (estrogen receptor and/or progesterone receptor positive/HER2-negative vs triple negative), prior neoadjuvant vs adjuvant chemotherapy, and prior platinum use for breast cancer. Treatment was continued for 52 weeks.

Setting and participants. A total of 1836 patients were randomized in a 1:1 fashion to receive olaparib or a placebo. Eligible patients had a germline BRCA1 or BRCA1 pathogenic or likely pathogenic variant. Patients had high-risk, HER2-negative primary breast cancers and all had received definitive local therapy and neoadjuvant or adjuvant chemotherapy. Patients were enrolled between 2 to 12 weeks after completion of all local therapy. Platinum chemotherapy was allowed. Patients received adjuvant endocrine therapy for hormone receptor positive disease as well as adjuvant bisphosphonates per institutional guidelines. Patients with triple negative disease who received adjuvant chemotherapy were required to be lymph node positive or have at least 2 cm invasive disease. Patients who received neoadjuvant chemotherapy were required to have residual invasive disease to be eligible. For hormone receptor positive patients receiving adjuvant chemotherapy to be eligible they had to have at least 4 pathologically confirmed lymph nodes involved. Hormone receptor positive patients who had neoadjuvant chemotherapy were required to have had residual invasive disease.

Main outcome measures. The primary endpoint for the study was invasive disease-free survival which was defined as time from randomization to date of recurrence or death from any cause. The secondary endpoints included overall survival (OS), distant disease-free survival, safety, and tolerability of olaparib.

Main results. At the time of data cutoff, 284 events had occurred with a median follow-up of 2.5 years in the intention to treat population. A total of 81% of patients had triple negative breast cancer. Most patients (94% in the olaparib group and 92% in the placebo group) received both taxane and anthracycline based chemotherapy regimens. Platinum based chemotherapy was used in 26% of patients in each group. The groups were otherwise well balanced. Germline mutations in BRCA1 were present in 72% of patients and BRCA2 in 27% of patients. These were balanced between groups.

At the time of this analysis, adjuvant olaparib reduced the risk of invasive disease-free survival by 42% compared with placebo (P < .001). At 3 years, invasive disease-free survival was 85.9% in the olaparib group and 77.1% in the placebo group (difference, 8.8 percentage points; 95% CI, 4.5-13.0; hazard ratio [HR], 0.58; 99.5% CI, 0.41-0.82; P < .001). The 3-year distant disease-free survival was 87.5% in the olaparib group and 80.4% in the placebo group (HR 0.57; 99.5% CI, 0.39-0.83; P < .001). Results also showed that olaparib was associated with fewer deaths than placebo (59 and 86, respectively) (HR, 0.68; 99% CI, 0.44-1.05; P = .02); however, there was no significant difference between treatment arms at the time of this interim analysis. Subgroup analysis showed a consistent benefit across all groups with no difference noted regarding BRCA mutation, hormone receptor status or use of neoadjuvant vs adjuvant chemotherapy.

The side effects were consistent with the safety profile of olaparib. Adverse events of grade 3 or higher more common with olaparib included anemia (8.7%), leukopenia (3%), and fatigue (1.8%). Early discontinuation of trial regimen due to adverse events of disease recurrence occurred in 25.9% in the olaparib group and 20.7% in the placebo group. Blood transfusions were required in 5.8% of patients in the olaparib group. Myelodysplasia or acute myleoid leukemia was observed in 2 patients in the olaparib group and 3 patients in the placebo group. Adverse events leading to death occurred in 1 patient in the olaparib group and 2 patients in the placebo group.

Conclusion. Among patients with high-risk, HER2-negative early breast cancer and germline BRCA1 or BRCA2 pathogenic or likely pathogenic variants, adjuvant olaparib after completion of local treatment and neoadjuvant or adjuvant chemotherapy was associated with significantly longer invasive disease-free and distant disease-free survival compared with placebo.

Commentary

The results from the current OlympiA trial provide the first evidence that adjuvant therapy with poly adenosine diphosphate-ribose polymerase (PARP) inhibitors can improve outcomes in high-risk, HER2-negative breast cancer in patients with pathogenic BRCA1 and BRCA2 mutations. The OS, while favoring olaparib, is not yet mature at the time of this analysis. Nevertheless, these results represent an important step forward in improving outcomes in this patient population. The efficacy and safety of PARP inhibitors in BRCA-mutated breast cancer has previously been shown in patients with advanced disease leading to FDA approval of both olaparib and talazoparib in this setting.^1,2 With the current results, PARP inhibitors will certainly play an important role in the adjuvant setting in patients with deleterious BRCA1 or BRCA2 mutations at high risk for relapse. Importantly, the side effect profile appears acceptable with no unexpected events and a very low rate of secondary myeloid malignancies.

Subgroup analysis appears to indicate a benefit across all groups including hormone receptor–positive disease and triple negative breast cancer. Interestingly, approximately 25% of patients in both cohorts received platinum-based chemotherapy. The efficacy of adjuvant olaparib did not appear to be impacted by prior use of platinum-containing chemotherapy regimens. It is important to consider that postneoadjuvant capecitabine, per the results of the CREATE-X trial, in triple-negative patients was not permitted in the current study. Although, this has been widely adopted in clinical practice.³ The CREATE-X trial did not specify the benefit of adjuvant capecitabine in the BRCA-mutated cohort, thus, it is not clear how this subgroup fares with this approach. Thus, one cannot extrapolate the relative efficacy of olaparib compared with capecitabine, as pointed out by the authors, and whether we consider the use of capecitabine and/or olaparib in triple-negative patients with residual invasive disease after neoadjuvant chemotherapy is not clear at this time.

Nevertheless, the magnitude of benefit seen in this trial certainly provide clinically relevant and potentially practice changing results. It will be imperative to follow these results as the survival data matures and ensure no further long-term toxicity, particularly secondary myeloid malignancies, develop. These results should be discussed with each patient and informed decisions regarding the use of adjuvant olaparib should be considered for this patient population. Lastly, these results highlight the importance of germline testing for patients with breast cancer in accordance with national guideline recommendations. Moreover, these results certainly call into question whether it is time to consider expansion of our current germline testing guidelines to detect all potential patients who may benefit from this therapy.

Application for Clinical Practice

Adjuvant olaparib in high-risk patients with germline BRCA1 or BRCA2 mutations improves invasive and distant disease-free survival and should be considered in patients who meet the enrollment criteria of the current study. Furthermore, this highlights the importance of appropriate germline genetic testing in patients with breast cancer.

Financial disclosures: None.

Study Overview

Objective. To evaluate the efficacy and safety of the combination of nivolumab plus cabozantinib as compared with sunitinib monotherapy in the treatment of previously untreated advanced renal cell carcinoma (RCC).

Design. Multicenter, international, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 fashion to 1 of 2 treatment arms:

• Arm A: Nivolumab intravenously 240 mg every 2 weeks plus cabozantinib orally 40 mg once daily.
• Arm B: Sunitinib orally 50 mg daily for 4 weeks, followed by 2 weeks off therapy (6-week cycle).

Randomization was stratified by the International Metastatic RCC Database Consortium prognostic risk score (low-, intermediate-, and high-risk). Treatment was continued until disease progression or development of unacceptable toxic side effects with a maximum of 2-year duration of Nivolumab therapy.

Settings and participants. Adults with previously untreated advanced RCC with a clear cell component were eligible for enrollment. Subjects were excluded if they had active central nervous system metastases or active autoimmune disease.

Main outcome measures. The primary outcome of this study was progression-free survival (PFS) as assessed by an independent review committee. Secondary endpoints included overall survival, objective response rate, safety, and PFS as assessed by investigators. All subgroup analyses were prespecified. Efficacy was assessed in the intention-to-treat population, including all patients who underwent randomization.

Main results. A total of 651 patients underwent randomization: 323 to the nivolumab plus cabozantinib group, and 328 to the sunitinib group. Baseline demographics were balanced. The median follow-up period for overall survival (OS) was 18.1 months. The primary reason for treatment discontinuation in any group was disease progression. PFS as indicated by an independent review committee was significantly longer in the nivolumab plus cabozantinib group compared to the sunitinib group (median 16.6 months vs 8.2 months; hazard ratio [HR] 0.51, P < .001). The median OS was not reached for any group. Overall survival was longer in the nivolumab plus cabozantinib group compared to the sunitinib group (HR 0.60, 95% CI: 0.40-0.89; P = .001). The objective response rate was 55.7% with the nivolumab plus cabozantinib group versus 27.1% with sunitinib (P < .001). The complete response rate was 8% in the nivolumab plus cabozantinib group compared to 4.6% in the sunitinib group. The median time to response was 2.8 months with nivolumab plus cabozantinib and 4.2 months in the sunitinib group, while the median duration of response was 20.2 months and 11.5 months, respectively.

Nearly all patients (about 99% in each group) had an adverse event (AE). Hypertension was the most common side effect, with grade 3 or higher seen in 12.5% in the nivolumab plus cabzantinib group and 13.1% in the sunitinib group. Other grade 3 or higher side effects occurring in at least 10% of patients in any group were hyponatremia, diarrhea, palmar-plantar erythrodysesthesia, hypothyroidism, and fatigue. AEs of any cause leading to discontinuation of the therapy occurred in 19.7% in the nivolumab plus cabzantinib group vs 16.9% of the sunitinib group. One death was considered to be treatment-related (small intestinal perforation) in the nivolumab plus cabozantinib group vs 2 treatment-related deaths with sunitinib (pneumonia and respiratory distress). In the nivolumab plus cabozantinib group, 57% of the patients had a dose reduction of cabozantinib and 52% had a reduction in sunitinib dosage.

Using the Functional Assessment of Cancer Therapy-Kidney Symptoms Index, patients in the nivolumab plus cabozantinib group reported better health-related quality of life and less disease-related symptoms compared to the sunitinib group.

Commentary

The treatment landscape for frontline therapy for patients with advanced RCC has rapidly expanded over the last several years and has revolutionized cancer care. Ushered in by the results from the CheckMate 214 study highlighting the efficacy of dual checkpoint inhibition with nivolumab and ipilimumab in intermediate and poor risk patients, several subsequent trials have demonstrated improved outcomes with combination therapy with immune checkpoint inhibitors and tyrosine-kinase inhibitors (TKI). To date, data from Keynote-426 (pembrolizumab plus axitinib vs sunitinib), Javelin Renal 101 (avelumab plus axitinib vs sunitinib) and the CLEAR trial (lenvatinib plus pembrolizumab vs levatinib plus everolimus vs sunitinib) have demonstrated superiority of immune checkpoint inhibitor/TKI combinations over sunitinb in the first-line setting.^1-5

The current phase 3, CheckMate 9ER trial adds yet another dynamic option for patients with advanced clear cell RCC. While cross-trial comparisons are fraught with important caveats, the median PFS of almost 16.6 months and complete response rate of 8% the nivolumab plus cabozantinib group compares favorably with other combinations. Data from the CLEAR study with the combination of lenvatinib and pembrolizumab showed a complete response rate approaching 16%. Importantly, the current study highlights improved quality of life with the combination of cabozantinib and nivolumab compared to sunitinib alone adding to the efficacy and benefits of this combination treatment.

The selection of first line therapy for patients with advanced RCC should be always guided by individual patient characteristics, and any single immune checkpoint inhibitor/TKI combination is not “superior” to any other. Perhaps more importantly is developing an understanding of the overlapping toxicity profiles of checkpoint inhibitors and TKIs. Again, this trial results are consistent with prior studies in terms of the adverse event profile which were not trivial, and almost all patients (99%) experienced AEs. It is important for oncologists to understand the management of the toxicities with these combinations and dose reductions as appropriate. It is worth noting that 19% of patients with nivolumab plus cabozantinib received glucocorticoids for management of immune-related AEs.

While long-term follow-up data will be needed to further understand the durability of response to this combination, nivolumab-cabozantinib represents an exciting new option for patients with advanced clear cell RCC. As we continue to see improvement in outcomes in clear cell histology, further work must focus on optimization of therapy in non-clear cell RCC as this is a population that is not represented in these data sets. Furthermore, future efforts should begin to explore triplet combinations and biomarker driven patient selection for upfront therapy in ordercontinue to improve outcomes in patients with advanced RCC.

Applications for Clinical Practice

The combination of nivolumab plus cabozantinib adds to the growing list of highly active checkpoint inhibitor/TKI combinations for first-line treatment of advanced RCC. With significant higher response rates, improved outcomes, and improvement in the quality of life, this combination will add another standard treatment option for patients with previously untreated advanced RCC.

Study Overview

Objective. To evaluate the efficacy and safety of the combination of nivolumab plus cabozantinib as compared with sunitinib monotherapy in the treatment of previously untreated advanced renal cell carcinoma (RCC).

Design. Multicenter, international, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 fashion to 1 of 2 treatment arms:

• Arm A: Nivolumab intravenously 240 mg every 2 weeks plus cabozantinib orally 40 mg once daily.
• Arm B: Sunitinib orally 50 mg daily for 4 weeks, followed by 2 weeks off therapy (6-week cycle).

Randomization was stratified by the International Metastatic RCC Database Consortium prognostic risk score (low-, intermediate-, and high-risk). Treatment was continued until disease progression or development of unacceptable toxic side effects with a maximum of 2-year duration of Nivolumab therapy.

Settings and participants. Adults with previously untreated advanced RCC with a clear cell component were eligible for enrollment. Subjects were excluded if they had active central nervous system metastases or active autoimmune disease.

Main outcome measures. The primary outcome of this study was progression-free survival (PFS) as assessed by an independent review committee. Secondary endpoints included overall survival, objective response rate, safety, and PFS as assessed by investigators. All subgroup analyses were prespecified. Efficacy was assessed in the intention-to-treat population, including all patients who underwent randomization.

Main results. A total of 651 patients underwent randomization: 323 to the nivolumab plus cabozantinib group, and 328 to the sunitinib group. Baseline demographics were balanced. The median follow-up period for overall survival (OS) was 18.1 months. The primary reason for treatment discontinuation in any group was disease progression. PFS as indicated by an independent review committee was significantly longer in the nivolumab plus cabozantinib group compared to the sunitinib group (median 16.6 months vs 8.2 months; hazard ratio [HR] 0.51, P < .001). The median OS was not reached for any group. Overall survival was longer in the nivolumab plus cabozantinib group compared to the sunitinib group (HR 0.60, 95% CI: 0.40-0.89; P = .001). The objective response rate was 55.7% with the nivolumab plus cabozantinib group versus 27.1% with sunitinib (P < .001). The complete response rate was 8% in the nivolumab plus cabozantinib group compared to 4.6% in the sunitinib group. The median time to response was 2.8 months with nivolumab plus cabozantinib and 4.2 months in the sunitinib group, while the median duration of response was 20.2 months and 11.5 months, respectively.

Nearly all patients (about 99% in each group) had an adverse event (AE). Hypertension was the most common side effect, with grade 3 or higher seen in 12.5% in the nivolumab plus cabzantinib group and 13.1% in the sunitinib group. Other grade 3 or higher side effects occurring in at least 10% of patients in any group were hyponatremia, diarrhea, palmar-plantar erythrodysesthesia, hypothyroidism, and fatigue. AEs of any cause leading to discontinuation of the therapy occurred in 19.7% in the nivolumab plus cabzantinib group vs 16.9% of the sunitinib group. One death was considered to be treatment-related (small intestinal perforation) in the nivolumab plus cabozantinib group vs 2 treatment-related deaths with sunitinib (pneumonia and respiratory distress). In the nivolumab plus cabozantinib group, 57% of the patients had a dose reduction of cabozantinib and 52% had a reduction in sunitinib dosage.

Using the Functional Assessment of Cancer Therapy-Kidney Symptoms Index, patients in the nivolumab plus cabozantinib group reported better health-related quality of life and less disease-related symptoms compared to the sunitinib group.

Commentary

The treatment landscape for frontline therapy for patients with advanced RCC has rapidly expanded over the last several years and has revolutionized cancer care. Ushered in by the results from the CheckMate 214 study highlighting the efficacy of dual checkpoint inhibition with nivolumab and ipilimumab in intermediate and poor risk patients, several subsequent trials have demonstrated improved outcomes with combination therapy with immune checkpoint inhibitors and tyrosine-kinase inhibitors (TKI). To date, data from Keynote-426 (pembrolizumab plus axitinib vs sunitinib), Javelin Renal 101 (avelumab plus axitinib vs sunitinib) and the CLEAR trial (lenvatinib plus pembrolizumab vs levatinib plus everolimus vs sunitinib) have demonstrated superiority of immune checkpoint inhibitor/TKI combinations over sunitinb in the first-line setting.^1-5

The current phase 3, CheckMate 9ER trial adds yet another dynamic option for patients with advanced clear cell RCC. While cross-trial comparisons are fraught with important caveats, the median PFS of almost 16.6 months and complete response rate of 8% the nivolumab plus cabozantinib group compares favorably with other combinations. Data from the CLEAR study with the combination of lenvatinib and pembrolizumab showed a complete response rate approaching 16%. Importantly, the current study highlights improved quality of life with the combination of cabozantinib and nivolumab compared to sunitinib alone adding to the efficacy and benefits of this combination treatment.

The selection of first line therapy for patients with advanced RCC should be always guided by individual patient characteristics, and any single immune checkpoint inhibitor/TKI combination is not “superior” to any other. Perhaps more importantly is developing an understanding of the overlapping toxicity profiles of checkpoint inhibitors and TKIs. Again, this trial results are consistent with prior studies in terms of the adverse event profile which were not trivial, and almost all patients (99%) experienced AEs. It is important for oncologists to understand the management of the toxicities with these combinations and dose reductions as appropriate. It is worth noting that 19% of patients with nivolumab plus cabozantinib received glucocorticoids for management of immune-related AEs.

While long-term follow-up data will be needed to further understand the durability of response to this combination, nivolumab-cabozantinib represents an exciting new option for patients with advanced clear cell RCC. As we continue to see improvement in outcomes in clear cell histology, further work must focus on optimization of therapy in non-clear cell RCC as this is a population that is not represented in these data sets. Furthermore, future efforts should begin to explore triplet combinations and biomarker driven patient selection for upfront therapy in ordercontinue to improve outcomes in patients with advanced RCC.

Applications for Clinical Practice

The combination of nivolumab plus cabozantinib adds to the growing list of highly active checkpoint inhibitor/TKI combinations for first-line treatment of advanced RCC. With significant higher response rates, improved outcomes, and improvement in the quality of life, this combination will add another standard treatment option for patients with previously untreated advanced RCC.

Study Overview

Objective. To evaluate the efficacy and safety of the combination of nivolumab plus cabozantinib as compared with sunitinib monotherapy in the treatment of previously untreated advanced renal cell carcinoma (RCC).

Design. Multicenter, international, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 fashion to 1 of 2 treatment arms:

• Arm A: Nivolumab intravenously 240 mg every 2 weeks plus cabozantinib orally 40 mg once daily.
• Arm B: Sunitinib orally 50 mg daily for 4 weeks, followed by 2 weeks off therapy (6-week cycle).

Randomization was stratified by the International Metastatic RCC Database Consortium prognostic risk score (low-, intermediate-, and high-risk). Treatment was continued until disease progression or development of unacceptable toxic side effects with a maximum of 2-year duration of Nivolumab therapy.

Settings and participants. Adults with previously untreated advanced RCC with a clear cell component were eligible for enrollment. Subjects were excluded if they had active central nervous system metastases or active autoimmune disease.

Main outcome measures. The primary outcome of this study was progression-free survival (PFS) as assessed by an independent review committee. Secondary endpoints included overall survival, objective response rate, safety, and PFS as assessed by investigators. All subgroup analyses were prespecified. Efficacy was assessed in the intention-to-treat population, including all patients who underwent randomization.

Main results. A total of 651 patients underwent randomization: 323 to the nivolumab plus cabozantinib group, and 328 to the sunitinib group. Baseline demographics were balanced. The median follow-up period for overall survival (OS) was 18.1 months. The primary reason for treatment discontinuation in any group was disease progression. PFS as indicated by an independent review committee was significantly longer in the nivolumab plus cabozantinib group compared to the sunitinib group (median 16.6 months vs 8.2 months; hazard ratio [HR] 0.51, P < .001). The median OS was not reached for any group. Overall survival was longer in the nivolumab plus cabozantinib group compared to the sunitinib group (HR 0.60, 95% CI: 0.40-0.89; P = .001). The objective response rate was 55.7% with the nivolumab plus cabozantinib group versus 27.1% with sunitinib (P < .001). The complete response rate was 8% in the nivolumab plus cabozantinib group compared to 4.6% in the sunitinib group. The median time to response was 2.8 months with nivolumab plus cabozantinib and 4.2 months in the sunitinib group, while the median duration of response was 20.2 months and 11.5 months, respectively.

Nearly all patients (about 99% in each group) had an adverse event (AE). Hypertension was the most common side effect, with grade 3 or higher seen in 12.5% in the nivolumab plus cabzantinib group and 13.1% in the sunitinib group. Other grade 3 or higher side effects occurring in at least 10% of patients in any group were hyponatremia, diarrhea, palmar-plantar erythrodysesthesia, hypothyroidism, and fatigue. AEs of any cause leading to discontinuation of the therapy occurred in 19.7% in the nivolumab plus cabzantinib group vs 16.9% of the sunitinib group. One death was considered to be treatment-related (small intestinal perforation) in the nivolumab plus cabozantinib group vs 2 treatment-related deaths with sunitinib (pneumonia and respiratory distress). In the nivolumab plus cabozantinib group, 57% of the patients had a dose reduction of cabozantinib and 52% had a reduction in sunitinib dosage.

Using the Functional Assessment of Cancer Therapy-Kidney Symptoms Index, patients in the nivolumab plus cabozantinib group reported better health-related quality of life and less disease-related symptoms compared to the sunitinib group.

Commentary

The treatment landscape for frontline therapy for patients with advanced RCC has rapidly expanded over the last several years and has revolutionized cancer care. Ushered in by the results from the CheckMate 214 study highlighting the efficacy of dual checkpoint inhibition with nivolumab and ipilimumab in intermediate and poor risk patients, several subsequent trials have demonstrated improved outcomes with combination therapy with immune checkpoint inhibitors and tyrosine-kinase inhibitors (TKI). To date, data from Keynote-426 (pembrolizumab plus axitinib vs sunitinib), Javelin Renal 101 (avelumab plus axitinib vs sunitinib) and the CLEAR trial (lenvatinib plus pembrolizumab vs levatinib plus everolimus vs sunitinib) have demonstrated superiority of immune checkpoint inhibitor/TKI combinations over sunitinb in the first-line setting.^1-5

The current phase 3, CheckMate 9ER trial adds yet another dynamic option for patients with advanced clear cell RCC. While cross-trial comparisons are fraught with important caveats, the median PFS of almost 16.6 months and complete response rate of 8% the nivolumab plus cabozantinib group compares favorably with other combinations. Data from the CLEAR study with the combination of lenvatinib and pembrolizumab showed a complete response rate approaching 16%. Importantly, the current study highlights improved quality of life with the combination of cabozantinib and nivolumab compared to sunitinib alone adding to the efficacy and benefits of this combination treatment.

The selection of first line therapy for patients with advanced RCC should be always guided by individual patient characteristics, and any single immune checkpoint inhibitor/TKI combination is not “superior” to any other. Perhaps more importantly is developing an understanding of the overlapping toxicity profiles of checkpoint inhibitors and TKIs. Again, this trial results are consistent with prior studies in terms of the adverse event profile which were not trivial, and almost all patients (99%) experienced AEs. It is important for oncologists to understand the management of the toxicities with these combinations and dose reductions as appropriate. It is worth noting that 19% of patients with nivolumab plus cabozantinib received glucocorticoids for management of immune-related AEs.

While long-term follow-up data will be needed to further understand the durability of response to this combination, nivolumab-cabozantinib represents an exciting new option for patients with advanced clear cell RCC. As we continue to see improvement in outcomes in clear cell histology, further work must focus on optimization of therapy in non-clear cell RCC as this is a population that is not represented in these data sets. Furthermore, future efforts should begin to explore triplet combinations and biomarker driven patient selection for upfront therapy in ordercontinue to improve outcomes in patients with advanced RCC.

Applications for Clinical Practice

The combination of nivolumab plus cabozantinib adds to the growing list of highly active checkpoint inhibitor/TKI combinations for first-line treatment of advanced RCC. With significant higher response rates, improved outcomes, and improvement in the quality of life, this combination will add another standard treatment option for patients with previously untreated advanced RCC.

Study Overview

Objective. To evaluate the efficacy of maintenance avelumab in patients with advanced urothelial carcinoma who had received first-line platinum-based chemotherapy.

Design. International, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 ratio to receive either maintenance therapy with avelumab 10 mg/kg plus best supportive care (BSC) or BSC alone, per local practice. Randomization was stratified according to best response to first-line chemotherapy and metastatic site (visceral vs nonvisceral). Treatment was continued until progression, unacceptable toxicities, or patient withdrawal occurred.

Setting and participants. A total of 700 patients were enrolled at 197 sites (350 in the avelumab group and 350 in the BSC group). All patients had histologically confirmed unresectable or metastatic urothelial carcinoma. Patients received 4 to 6 cycles of chemotherapy with either gemcitabine plus cisplatin or carboplatin and had no evidence of progression after completion. Patients had a treatment-free interval of 4 to 10 weeks prior to starting maintenance therapy. Patients who received neoadjuvant or adjuvant platinum-based therapy within the prior 12 months were excluded.

Main outcome measures. The primary endpoint was overall survival (OS) assessed in both the overall population and PD-L1–positive population. Secondary endpoints included progression-free survival (PFS), objective response, time to response, duration of response, and disease control. PD-L1 expression was determined via the Ventana PD-L1 assay (SP263), and patients were classified as PD-L1 positive if they met 1 of the following: (1) at least 25% of tumor cells were positive for PD-L1; (2) at least 25% of immune cells were positive for PD-L1 if more than 1% of the tumor area contained immune cells; and (3) 100% of immune cells stained for PD-L1 if no more than 1% of the tumor area contained immune cells.

Results. The baseline characteristics were well balanced between the groups. A total of 51.1% of patients had PD-L1–positive tumors (57.6% in the avelumab group and 56.3% in the control group). At the time of analysis, 24% of patients in the avelumab group were still receiving therapy compared with only 7% in the BSC group. The most common reason for discontinuation of therapy was disease progression; 43.7% of patients in the control group received anti-PD-1 or anti-PD-L1 therapy at progression. The median follow-up was 19 months. OS at 1 year was 71.3% in the avelumab group and 58.4% in the control group. The median OS was 21.4 months in the avelumab group compared with 14.3 months in the control group (hazard ratio [HR] for death, 0.69; confidence interval [CI], 0.56-0.86, P = 0.001). In the PD-L1–positive population, OS was also significantly longer in the avelumab group (NE vs 17.1 months, HR, 0.56; CI, 0.40-0.79; P < 0.001). In the PD-L1–negative population, median OS was 18.8 months in the avelumab group versus 13.7 months in the control group (HR, 0.85). PFS was longer in the avelumab group than in the control group, with a median PFS of 3.7 months versus 2 months, respectively. The median PFS was 5.7 months in the avelumab group and 2.1 months in the control group in the PD-L1–positive population.

Adverse events (AEs) of any grade occurred in 98% of patients in the avelumab group and 77% in the control group. Grade 3 or higher AEs occurred in 47.4% of patients in the avelumab group. AEs led to discontinuation in 11.9% of patients in the avelumab group. Two patients died in the avelumab group as a result of toxicity (urinary tract infection with sepsis and ischemic stroke). Immune-related adverse events occurred in 29.4% of patients in the avelumab group. Of those, 7% were grade 3 in nature, and there were no grade 4 or 5 immune-related AEs. The most commonly seen immune-related AEs were thyroid disorders.

Conclusion. Avelumab maintenance significantly improved OS compared with BSC in patients with advanced/metastatic urothelial carcinoma whose disease did not progress after first-line platinum-based chemotherapy.

Commentary

In summary, the JAVELIN Bladder 100 trial showed significantly longer OS with the use of maintenance avelumab following first-line platinum-based chemotherapy. This survival benefit was seen in all subgroups, including those who received cisplatin or carboplatin therapy, as well as those with stable disease, partial response, or complete response to initial chemotherapy. Furthermore, the survival benefit was seen in both the overall population as well as in the PD-L1–positive population. There did not appear to be any new safety concerns noted in this trial. Based on these findings, avelumab maintenance in those who do not progress on first-line platinum-based therapy certainly represents a potentially new standard of care in this patient population. While the results of this study are promising and potentially practice changing, whether this “switch maintenance” approach is superior to treatment at progression (ie, use of checkpoint inhibition in the second-line setting) remains debatable. Nevertheless, for most patients, this appears to be the preferred approach given the notable longer OS and improved PFS, which is meaningful, particularly if the progression event is symptomatic. Furthermore, a portion of patients will not proceed to second-line therapy for a variety of reasons, and thus will not be exposed to checkpoint inhibitors if one takes a treatment break approach.

In the previous KEYNOTE-45 study evaluating pembrolizumab versus chemotherapy in the second-line setting after progression on previous platinum therapy, the median OS was just 10 months in the pembrolizumab arm.¹ This is markedly different from the 21.4-month median OS noted in the current study. While there are many limitations to this comparison, it does appear that switch maintenance leads to meaningful improvements in patient outcomes. It should be noted, however, that a portion of patients will have a durable response to platinum-based therapy, and thus there may be a portion of patients who would be “overtreated” with such an approach.

A similar approach has been explored in a randomized phase 2 trial looking at maintenance pembrolizumab after first-line chemotherapy (HCRN GU14-182).² This trial similarly showed improvement in PFS; however, OS was not yet mature at the time of data analysis. It should be noted that crossover was permitted in the HCRN study, while this was not allowed in the current Javelin 100 study. Certainly, this crossover effect influenced OS data in that trial. Thus, the current study is the first and only to show an OS benefit with such an approach in this population. Numerous ongoing studies are seeking to evaluate the efficacy of immune checkpoint inhibitors in the first-line setting for advanced urothelial carcinoma, and the results of these studies will help shed additional light regarding the efficacy of this approach.

Applications for Clinical Practice

First-line maintenance avelumab in patients who do not progress on platinum-based chemotherapy improves both progression-free and overall survival. This approach is certainly practice-changing and represents a new standard of care in this patient population. Careful discussion with each patient about the benefits and risks of a switch maintenance approach is warranted.

Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of maintenance avelumab in patients with advanced urothelial carcinoma who had received first-line platinum-based chemotherapy.

Design. International, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 ratio to receive either maintenance therapy with avelumab 10 mg/kg plus best supportive care (BSC) or BSC alone, per local practice. Randomization was stratified according to best response to first-line chemotherapy and metastatic site (visceral vs nonvisceral). Treatment was continued until progression, unacceptable toxicities, or patient withdrawal occurred.

Setting and participants. A total of 700 patients were enrolled at 197 sites (350 in the avelumab group and 350 in the BSC group). All patients had histologically confirmed unresectable or metastatic urothelial carcinoma. Patients received 4 to 6 cycles of chemotherapy with either gemcitabine plus cisplatin or carboplatin and had no evidence of progression after completion. Patients had a treatment-free interval of 4 to 10 weeks prior to starting maintenance therapy. Patients who received neoadjuvant or adjuvant platinum-based therapy within the prior 12 months were excluded.

Main outcome measures. The primary endpoint was overall survival (OS) assessed in both the overall population and PD-L1–positive population. Secondary endpoints included progression-free survival (PFS), objective response, time to response, duration of response, and disease control. PD-L1 expression was determined via the Ventana PD-L1 assay (SP263), and patients were classified as PD-L1 positive if they met 1 of the following: (1) at least 25% of tumor cells were positive for PD-L1; (2) at least 25% of immune cells were positive for PD-L1 if more than 1% of the tumor area contained immune cells; and (3) 100% of immune cells stained for PD-L1 if no more than 1% of the tumor area contained immune cells.

Results. The baseline characteristics were well balanced between the groups. A total of 51.1% of patients had PD-L1–positive tumors (57.6% in the avelumab group and 56.3% in the control group). At the time of analysis, 24% of patients in the avelumab group were still receiving therapy compared with only 7% in the BSC group. The most common reason for discontinuation of therapy was disease progression; 43.7% of patients in the control group received anti-PD-1 or anti-PD-L1 therapy at progression. The median follow-up was 19 months. OS at 1 year was 71.3% in the avelumab group and 58.4% in the control group. The median OS was 21.4 months in the avelumab group compared with 14.3 months in the control group (hazard ratio [HR] for death, 0.69; confidence interval [CI], 0.56-0.86, P = 0.001). In the PD-L1–positive population, OS was also significantly longer in the avelumab group (NE vs 17.1 months, HR, 0.56; CI, 0.40-0.79; P < 0.001). In the PD-L1–negative population, median OS was 18.8 months in the avelumab group versus 13.7 months in the control group (HR, 0.85). PFS was longer in the avelumab group than in the control group, with a median PFS of 3.7 months versus 2 months, respectively. The median PFS was 5.7 months in the avelumab group and 2.1 months in the control group in the PD-L1–positive population.

Adverse events (AEs) of any grade occurred in 98% of patients in the avelumab group and 77% in the control group. Grade 3 or higher AEs occurred in 47.4% of patients in the avelumab group. AEs led to discontinuation in 11.9% of patients in the avelumab group. Two patients died in the avelumab group as a result of toxicity (urinary tract infection with sepsis and ischemic stroke). Immune-related adverse events occurred in 29.4% of patients in the avelumab group. Of those, 7% were grade 3 in nature, and there were no grade 4 or 5 immune-related AEs. The most commonly seen immune-related AEs were thyroid disorders.

Conclusion. Avelumab maintenance significantly improved OS compared with BSC in patients with advanced/metastatic urothelial carcinoma whose disease did not progress after first-line platinum-based chemotherapy.

Commentary

In summary, the JAVELIN Bladder 100 trial showed significantly longer OS with the use of maintenance avelumab following first-line platinum-based chemotherapy. This survival benefit was seen in all subgroups, including those who received cisplatin or carboplatin therapy, as well as those with stable disease, partial response, or complete response to initial chemotherapy. Furthermore, the survival benefit was seen in both the overall population as well as in the PD-L1–positive population. There did not appear to be any new safety concerns noted in this trial. Based on these findings, avelumab maintenance in those who do not progress on first-line platinum-based therapy certainly represents a potentially new standard of care in this patient population. While the results of this study are promising and potentially practice changing, whether this “switch maintenance” approach is superior to treatment at progression (ie, use of checkpoint inhibition in the second-line setting) remains debatable. Nevertheless, for most patients, this appears to be the preferred approach given the notable longer OS and improved PFS, which is meaningful, particularly if the progression event is symptomatic. Furthermore, a portion of patients will not proceed to second-line therapy for a variety of reasons, and thus will not be exposed to checkpoint inhibitors if one takes a treatment break approach.

In the previous KEYNOTE-45 study evaluating pembrolizumab versus chemotherapy in the second-line setting after progression on previous platinum therapy, the median OS was just 10 months in the pembrolizumab arm.¹ This is markedly different from the 21.4-month median OS noted in the current study. While there are many limitations to this comparison, it does appear that switch maintenance leads to meaningful improvements in patient outcomes. It should be noted, however, that a portion of patients will have a durable response to platinum-based therapy, and thus there may be a portion of patients who would be “overtreated” with such an approach.

A similar approach has been explored in a randomized phase 2 trial looking at maintenance pembrolizumab after first-line chemotherapy (HCRN GU14-182).² This trial similarly showed improvement in PFS; however, OS was not yet mature at the time of data analysis. It should be noted that crossover was permitted in the HCRN study, while this was not allowed in the current Javelin 100 study. Certainly, this crossover effect influenced OS data in that trial. Thus, the current study is the first and only to show an OS benefit with such an approach in this population. Numerous ongoing studies are seeking to evaluate the efficacy of immune checkpoint inhibitors in the first-line setting for advanced urothelial carcinoma, and the results of these studies will help shed additional light regarding the efficacy of this approach.

Applications for Clinical Practice

First-line maintenance avelumab in patients who do not progress on platinum-based chemotherapy improves both progression-free and overall survival. This approach is certainly practice-changing and represents a new standard of care in this patient population. Careful discussion with each patient about the benefits and risks of a switch maintenance approach is warranted.

Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of maintenance avelumab in patients with advanced urothelial carcinoma who had received first-line platinum-based chemotherapy.

Design. International, open-label, randomized, phase 3 trial.

Intervention. Patients were randomized in a 1:1 ratio to receive either maintenance therapy with avelumab 10 mg/kg plus best supportive care (BSC) or BSC alone, per local practice. Randomization was stratified according to best response to first-line chemotherapy and metastatic site (visceral vs nonvisceral). Treatment was continued until progression, unacceptable toxicities, or patient withdrawal occurred.

Setting and participants. A total of 700 patients were enrolled at 197 sites (350 in the avelumab group and 350 in the BSC group). All patients had histologically confirmed unresectable or metastatic urothelial carcinoma. Patients received 4 to 6 cycles of chemotherapy with either gemcitabine plus cisplatin or carboplatin and had no evidence of progression after completion. Patients had a treatment-free interval of 4 to 10 weeks prior to starting maintenance therapy. Patients who received neoadjuvant or adjuvant platinum-based therapy within the prior 12 months were excluded.

Main outcome measures. The primary endpoint was overall survival (OS) assessed in both the overall population and PD-L1–positive population. Secondary endpoints included progression-free survival (PFS), objective response, time to response, duration of response, and disease control. PD-L1 expression was determined via the Ventana PD-L1 assay (SP263), and patients were classified as PD-L1 positive if they met 1 of the following: (1) at least 25% of tumor cells were positive for PD-L1; (2) at least 25% of immune cells were positive for PD-L1 if more than 1% of the tumor area contained immune cells; and (3) 100% of immune cells stained for PD-L1 if no more than 1% of the tumor area contained immune cells.

Results. The baseline characteristics were well balanced between the groups. A total of 51.1% of patients had PD-L1–positive tumors (57.6% in the avelumab group and 56.3% in the control group). At the time of analysis, 24% of patients in the avelumab group were still receiving therapy compared with only 7% in the BSC group. The most common reason for discontinuation of therapy was disease progression; 43.7% of patients in the control group received anti-PD-1 or anti-PD-L1 therapy at progression. The median follow-up was 19 months. OS at 1 year was 71.3% in the avelumab group and 58.4% in the control group. The median OS was 21.4 months in the avelumab group compared with 14.3 months in the control group (hazard ratio [HR] for death, 0.69; confidence interval [CI], 0.56-0.86, P = 0.001). In the PD-L1–positive population, OS was also significantly longer in the avelumab group (NE vs 17.1 months, HR, 0.56; CI, 0.40-0.79; P < 0.001). In the PD-L1–negative population, median OS was 18.8 months in the avelumab group versus 13.7 months in the control group (HR, 0.85). PFS was longer in the avelumab group than in the control group, with a median PFS of 3.7 months versus 2 months, respectively. The median PFS was 5.7 months in the avelumab group and 2.1 months in the control group in the PD-L1–positive population.

Adverse events (AEs) of any grade occurred in 98% of patients in the avelumab group and 77% in the control group. Grade 3 or higher AEs occurred in 47.4% of patients in the avelumab group. AEs led to discontinuation in 11.9% of patients in the avelumab group. Two patients died in the avelumab group as a result of toxicity (urinary tract infection with sepsis and ischemic stroke). Immune-related adverse events occurred in 29.4% of patients in the avelumab group. Of those, 7% were grade 3 in nature, and there were no grade 4 or 5 immune-related AEs. The most commonly seen immune-related AEs were thyroid disorders.

Conclusion. Avelumab maintenance significantly improved OS compared with BSC in patients with advanced/metastatic urothelial carcinoma whose disease did not progress after first-line platinum-based chemotherapy.

Commentary

In summary, the JAVELIN Bladder 100 trial showed significantly longer OS with the use of maintenance avelumab following first-line platinum-based chemotherapy. This survival benefit was seen in all subgroups, including those who received cisplatin or carboplatin therapy, as well as those with stable disease, partial response, or complete response to initial chemotherapy. Furthermore, the survival benefit was seen in both the overall population as well as in the PD-L1–positive population. There did not appear to be any new safety concerns noted in this trial. Based on these findings, avelumab maintenance in those who do not progress on first-line platinum-based therapy certainly represents a potentially new standard of care in this patient population. While the results of this study are promising and potentially practice changing, whether this “switch maintenance” approach is superior to treatment at progression (ie, use of checkpoint inhibition in the second-line setting) remains debatable. Nevertheless, for most patients, this appears to be the preferred approach given the notable longer OS and improved PFS, which is meaningful, particularly if the progression event is symptomatic. Furthermore, a portion of patients will not proceed to second-line therapy for a variety of reasons, and thus will not be exposed to checkpoint inhibitors if one takes a treatment break approach.

In the previous KEYNOTE-45 study evaluating pembrolizumab versus chemotherapy in the second-line setting after progression on previous platinum therapy, the median OS was just 10 months in the pembrolizumab arm.¹ This is markedly different from the 21.4-month median OS noted in the current study. While there are many limitations to this comparison, it does appear that switch maintenance leads to meaningful improvements in patient outcomes. It should be noted, however, that a portion of patients will have a durable response to platinum-based therapy, and thus there may be a portion of patients who would be “overtreated” with such an approach.

A similar approach has been explored in a randomized phase 2 trial looking at maintenance pembrolizumab after first-line chemotherapy (HCRN GU14-182).² This trial similarly showed improvement in PFS; however, OS was not yet mature at the time of data analysis. It should be noted that crossover was permitted in the HCRN study, while this was not allowed in the current Javelin 100 study. Certainly, this crossover effect influenced OS data in that trial. Thus, the current study is the first and only to show an OS benefit with such an approach in this population. Numerous ongoing studies are seeking to evaluate the efficacy of immune checkpoint inhibitors in the first-line setting for advanced urothelial carcinoma, and the results of these studies will help shed additional light regarding the efficacy of this approach.

Applications for Clinical Practice

First-line maintenance avelumab in patients who do not progress on platinum-based chemotherapy improves both progression-free and overall survival. This approach is certainly practice-changing and represents a new standard of care in this patient population. Careful discussion with each patient about the benefits and risks of a switch maintenance approach is warranted.

Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.

Design. International, multicenter, randomized, double-blind, phase 3 trial.

Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m² plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m² or epirubicin 90 mg/m² plus cyclophosphamide 600 mg/m² once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.

Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.

Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.

Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.

Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.

Commentary

The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.¹ Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.² While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.³ The results of the current study will require longer-term follow-up to confirm such an association.

The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.

It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.⁴ Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.⁵ How the use of adjuvant capecitabine would impact these results is completely unknown.⁶ The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.

Applications for Clinical Practice

KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.

– Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.

Design. International, multicenter, randomized, double-blind, phase 3 trial.

Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m² plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m² or epirubicin 90 mg/m² plus cyclophosphamide 600 mg/m² once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.

Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.

Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.

Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.

Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.

Commentary

The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.¹ Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.² While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.³ The results of the current study will require longer-term follow-up to confirm such an association.

The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.

It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.⁴ Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.⁵ How the use of adjuvant capecitabine would impact these results is completely unknown.⁶ The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.

Applications for Clinical Practice

KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.

– Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.

Design. International, multicenter, randomized, double-blind, phase 3 trial.

Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m² plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m² or epirubicin 90 mg/m² plus cyclophosphamide 600 mg/m² once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.

Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.

Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.

Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.

Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.

Commentary

The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.¹ Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.² While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.³ The results of the current study will require longer-term follow-up to confirm such an association.

The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.

It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.⁴ Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.⁵ How the use of adjuvant capecitabine would impact these results is completely unknown.⁶ The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.

Applications for Clinical Practice

KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.

– Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of cabazitaxel compared to androgen-signaling–targeted inhibitors (ASTIs) in patients with metastatic castration-resistant prostate cancer who have received docetaxel and have progressed within 12 months of treatment with either abiraterone or enzalutamide.

Design. The CARD trial was an international, randomized, open-label phase 3 trial conducted across 13 European countries.

Setting and participants. Eligible patients were 18 years of age or older; had metastatic castration-resistant prostate cancer previously treated with docetaxel; and had disease progression during 12 months of treatment with abiraterone or enzalutamide. All patients had histologically proven prostate cancer, castrate levels of serum testosterone, and disease progression, defined by at least 2 new bone lesions or rising prostate-specific antigen (PSA) level. A total of 255 patients underwent randomization between November 2015 and November 2018, with 129 assigned to receive cabazitaxel and 126 patients assigned to receive an ASTI, 58 of whom received abiraterone and 66 of whom received enzalutamide. Patients who had received an ASTI in the setting of castrate-sensitive metastatic prostate cancer were included.

Intervention. Patients were randomized in a 1:1 fashion to receive either cabazitaxel or abiraterone or enzalutamide. Patients receiving cabazitaxel 25 mg/m² intravenously every 3 weeks also received oral prednisone daily and primary prophylactic granulocyte-colony stimulating factor. Patients assigned to receive an ASTI received abiraterone 1000 mg orally daily with prednisone 5 mg twice daily or enzalutamide 160 mg daily. Patients in the ASTI group who had progressed on abiraterone were assigned to enzalutamide, and alternatively, those on enzalutamide were assigned to abiraterone. Patients were treated until 1 of the following occurred: imaging-based disease progression, unacceptable toxicity, or advancing to an alternative therapy.

Main outcome measures. The primary endpoint was imaging-based progression-free survival, which was defined as the time from randomization until objective tumor progression, progression of bone lesions, or death. The secondary endpoints were overall survival, progression-free survival, PSA response, tumor and pain responses, a new symptomatic skeletal event, and safety.

Results. The median follow-up was 9.2 months. Imaging-based disease progression or death from any cause occurred in 95 (73.6%) participants in the cabazitaxel group, as compared to 101 (80.2%) who were assigned to receive an ASTI. The median imaging-based progression-free survival was 8.0 months in the cabazitaxel group and 3.7 months in the abiraterone/enzalutamide group. The median duration of treatment was longer in those receiving cabazitaxel (22 vs 12.5 weeks). The primary reason for treatment discontinuation was disease progression (in 43.7% of patients receiving cabazitaxel and 71% receiving an ASTI) or an adverse event (19.8% and 8.9%, respectively).

The trial’s secondary endpoints demonstrated improved outcomes in the cabazitaxel group compared to the abiraterone/enzalutamide group. There were 70 deaths (54.2%) in the cabazitaxel group and 83 (65.9%) in the ASTI group. Both the median overall survival (13.6 months in the cabazitaxel group and 11 months in the ASTI group) and the median progression-free survival (4.4 months and 2.7 months, respectively) were improved in those who received cabazitaxel. There was a 50% or greater reduction in the PSA level from baseline in 35.7% of the cabazitaxel group and 13.5% of the ASTI group.

Regarding the safety of the agents, the incidence of adverse events was similar in each group (38.9% in the cabazitaxel group and 38.7% in the ASTI group). Treatment discontinuation occurred more frequently in the cabazitaxel group (19.8%) compared to the ASTI group (8.9%). Adverse events of grade 3 or higher occurred more frequently with cabazitaxel; these were asthenia (4% vs 2.4%), diarrhea (3.2% vs 0), peripheral neuropathy (3.2% vs 0 patients), and febrile neutropenia (3.2% vs 0 patients).

Conclusion. Patients who had disease progression within 12 months on an ASTI and had previously been treated for metastatic castration-resistant prostate cancer with docetaxel had longer imaging-based progression-free survival and overall survival when treated with cabazitaxel compared to those treated with an alternative ASTI. Other clinical outcomes, including overall survival and progression-free survival, were also improved in the cabazitaxel group.

Commentary

Four ASTIs are approved for therapy in men with advanced prostate cancer. The next line of therapy following progression on an ASTI, whether to consider second-line androgen targeted inhibitors or proceed to taxane-based chemotherapy, has been unclear. The current CARD trial sought to answer this question and provides evidence that cabazitaxel is the next line of therapy for these patients. The trial’s primary endpoint, imaging-based disease progression, was reported in 73.6% of those who received cabazitaxel and in 80.2% of those who received abiraterone or enzalutamide. Patients treated with cabazitaxel had a longer imaging-based progression-free survival (8.0 months vs 3.7 months) and a longer duration of treatment (22 vs 12.5 weeks).

Because there is clinical evidence of cross-resistance between different ASTIs, the value of sequential therapy has been unclear. Emergence of androgen-receptor splice variant 7 (AR-V7) mutational status in circulating tumor cells is associated with poor outcomes with secondary androgen-signaling inhibitor therapy, and may be an indicator of resistance to subsequent androgen-signaling inhibitors.^1,2 In the PROPHECY trial, the response rates to subsequent androgen targeted therapy in patients with AR-V7 mutations ranged from 30% to 40%.³ Understanding how AR-V7 mutational status may impact such outcomes will certainly help define whether a subgroup exists in whom use of second-line androgen signaling inhibitors may be considered.

The patients enrolled in the current study appear to represent a subgroup of patients with biologically aggressive disease or with inherent resistance to ASTIs. The patients included in this study progressed within 1 year of androgen targeted therapy, which is representative of a more aggressive population of patients who may be hormone insensitive and derive more benefit from chemotherapy. Initial androgen deprivation therapy was given for 13.7 and 12.6 months to the cabazitaxel and enzalutamide/abiraterone arms, respectively, prior to developing castrate-resistant prostate cancer. Patients enrolled in this study also previously received docetaxel, deselecting those who are taxane-resistant and therefore may be less likely to respond to additional taxane-based therapy. Detection of AR-V7 splice variant expression in circulating tumor cells, consideration of biomarker data, and sensitivity to taxanes may help guide decisions regarding the use of sequential androgen-targeted agents; however, there has been no clear data to guide such an approach. It is also important to consider that, because this is a European study, the approved dose given in this trial was 25 mg/m². The PROSELICA trial previously demonstrated noninferiority of 20 mg/m² compared with 25 mg/m², with fewer adverse events, which is the dose now utilized in the United States.⁴

The adverse events of grade 3 or greater occurring in the cabazitaxel group should be discussed with patients, including fatigue, diarrhea, peripheral neuropathy, and febrile neutropenia.

The data from the CARD trial provide guidance regarding therapy sequencing in those with advanced prostate cancer after progression on first-line androgen targeted inhibitors and docetaxel; however, further work is needed to understand the universal application of this data in this cohort.

Applications in Clinical Practice

Patients with metastatic castration-resistant prostate cancer who have received docetaxel and progressed on an androgen-signaling inhibitor within 12 months should be considered for cabazitaxel over an alternative androgen-signaling inhibitor. This decision should be based on several factors, including AR-V7 mutational status, duration of androgen deprivation therapy, and hormone and taxane sensitivity in the past. Future studies are likely to incorporate genomic biomarkers rather than clinical criteria alone to make treatment decisions.

–Britni Souther, DO, and Daniel Isaac, DO, MS, Michigan State University, East Lansing, MI

Study Overview

Objective. To evaluate the efficacy of cabazitaxel compared to androgen-signaling–targeted inhibitors (ASTIs) in patients with metastatic castration-resistant prostate cancer who have received docetaxel and have progressed within 12 months of treatment with either abiraterone or enzalutamide.

Design. The CARD trial was an international, randomized, open-label phase 3 trial conducted across 13 European countries.

Setting and participants. Eligible patients were 18 years of age or older; had metastatic castration-resistant prostate cancer previously treated with docetaxel; and had disease progression during 12 months of treatment with abiraterone or enzalutamide. All patients had histologically proven prostate cancer, castrate levels of serum testosterone, and disease progression, defined by at least 2 new bone lesions or rising prostate-specific antigen (PSA) level. A total of 255 patients underwent randomization between November 2015 and November 2018, with 129 assigned to receive cabazitaxel and 126 patients assigned to receive an ASTI, 58 of whom received abiraterone and 66 of whom received enzalutamide. Patients who had received an ASTI in the setting of castrate-sensitive metastatic prostate cancer were included.

Intervention. Patients were randomized in a 1:1 fashion to receive either cabazitaxel or abiraterone or enzalutamide. Patients receiving cabazitaxel 25 mg/m² intravenously every 3 weeks also received oral prednisone daily and primary prophylactic granulocyte-colony stimulating factor. Patients assigned to receive an ASTI received abiraterone 1000 mg orally daily with prednisone 5 mg twice daily or enzalutamide 160 mg daily. Patients in the ASTI group who had progressed on abiraterone were assigned to enzalutamide, and alternatively, those on enzalutamide were assigned to abiraterone. Patients were treated until 1 of the following occurred: imaging-based disease progression, unacceptable toxicity, or advancing to an alternative therapy.

Main outcome measures. The primary endpoint was imaging-based progression-free survival, which was defined as the time from randomization until objective tumor progression, progression of bone lesions, or death. The secondary endpoints were overall survival, progression-free survival, PSA response, tumor and pain responses, a new symptomatic skeletal event, and safety.

Results. The median follow-up was 9.2 months. Imaging-based disease progression or death from any cause occurred in 95 (73.6%) participants in the cabazitaxel group, as compared to 101 (80.2%) who were assigned to receive an ASTI. The median imaging-based progression-free survival was 8.0 months in the cabazitaxel group and 3.7 months in the abiraterone/enzalutamide group. The median duration of treatment was longer in those receiving cabazitaxel (22 vs 12.5 weeks). The primary reason for treatment discontinuation was disease progression (in 43.7% of patients receiving cabazitaxel and 71% receiving an ASTI) or an adverse event (19.8% and 8.9%, respectively).

The trial’s secondary endpoints demonstrated improved outcomes in the cabazitaxel group compared to the abiraterone/enzalutamide group. There were 70 deaths (54.2%) in the cabazitaxel group and 83 (65.9%) in the ASTI group. Both the median overall survival (13.6 months in the cabazitaxel group and 11 months in the ASTI group) and the median progression-free survival (4.4 months and 2.7 months, respectively) were improved in those who received cabazitaxel. There was a 50% or greater reduction in the PSA level from baseline in 35.7% of the cabazitaxel group and 13.5% of the ASTI group.

Regarding the safety of the agents, the incidence of adverse events was similar in each group (38.9% in the cabazitaxel group and 38.7% in the ASTI group). Treatment discontinuation occurred more frequently in the cabazitaxel group (19.8%) compared to the ASTI group (8.9%). Adverse events of grade 3 or higher occurred more frequently with cabazitaxel; these were asthenia (4% vs 2.4%), diarrhea (3.2% vs 0), peripheral neuropathy (3.2% vs 0 patients), and febrile neutropenia (3.2% vs 0 patients).

Conclusion. Patients who had disease progression within 12 months on an ASTI and had previously been treated for metastatic castration-resistant prostate cancer with docetaxel had longer imaging-based progression-free survival and overall survival when treated with cabazitaxel compared to those treated with an alternative ASTI. Other clinical outcomes, including overall survival and progression-free survival, were also improved in the cabazitaxel group.

Commentary

Four ASTIs are approved for therapy in men with advanced prostate cancer. The next line of therapy following progression on an ASTI, whether to consider second-line androgen targeted inhibitors or proceed to taxane-based chemotherapy, has been unclear. The current CARD trial sought to answer this question and provides evidence that cabazitaxel is the next line of therapy for these patients. The trial’s primary endpoint, imaging-based disease progression, was reported in 73.6% of those who received cabazitaxel and in 80.2% of those who received abiraterone or enzalutamide. Patients treated with cabazitaxel had a longer imaging-based progression-free survival (8.0 months vs 3.7 months) and a longer duration of treatment (22 vs 12.5 weeks).

Because there is clinical evidence of cross-resistance between different ASTIs, the value of sequential therapy has been unclear. Emergence of androgen-receptor splice variant 7 (AR-V7) mutational status in circulating tumor cells is associated with poor outcomes with secondary androgen-signaling inhibitor therapy, and may be an indicator of resistance to subsequent androgen-signaling inhibitors.^1,2 In the PROPHECY trial, the response rates to subsequent androgen targeted therapy in patients with AR-V7 mutations ranged from 30% to 40%.³ Understanding how AR-V7 mutational status may impact such outcomes will certainly help define whether a subgroup exists in whom use of second-line androgen signaling inhibitors may be considered.

The patients enrolled in the current study appear to represent a subgroup of patients with biologically aggressive disease or with inherent resistance to ASTIs. The patients included in this study progressed within 1 year of androgen targeted therapy, which is representative of a more aggressive population of patients who may be hormone insensitive and derive more benefit from chemotherapy. Initial androgen deprivation therapy was given for 13.7 and 12.6 months to the cabazitaxel and enzalutamide/abiraterone arms, respectively, prior to developing castrate-resistant prostate cancer. Patients enrolled in this study also previously received docetaxel, deselecting those who are taxane-resistant and therefore may be less likely to respond to additional taxane-based therapy. Detection of AR-V7 splice variant expression in circulating tumor cells, consideration of biomarker data, and sensitivity to taxanes may help guide decisions regarding the use of sequential androgen-targeted agents; however, there has been no clear data to guide such an approach. It is also important to consider that, because this is a European study, the approved dose given in this trial was 25 mg/m². The PROSELICA trial previously demonstrated noninferiority of 20 mg/m² compared with 25 mg/m², with fewer adverse events, which is the dose now utilized in the United States.⁴

The adverse events of grade 3 or greater occurring in the cabazitaxel group should be discussed with patients, including fatigue, diarrhea, peripheral neuropathy, and febrile neutropenia.

The data from the CARD trial provide guidance regarding therapy sequencing in those with advanced prostate cancer after progression on first-line androgen targeted inhibitors and docetaxel; however, further work is needed to understand the universal application of this data in this cohort.

Applications in Clinical Practice

Patients with metastatic castration-resistant prostate cancer who have received docetaxel and progressed on an androgen-signaling inhibitor within 12 months should be considered for cabazitaxel over an alternative androgen-signaling inhibitor. This decision should be based on several factors, including AR-V7 mutational status, duration of androgen deprivation therapy, and hormone and taxane sensitivity in the past. Future studies are likely to incorporate genomic biomarkers rather than clinical criteria alone to make treatment decisions.

–Britni Souther, DO, and Daniel Isaac, DO, MS, Michigan State University, East Lansing, MI

Study Overview

Objective. To evaluate the efficacy of cabazitaxel compared to androgen-signaling–targeted inhibitors (ASTIs) in patients with metastatic castration-resistant prostate cancer who have received docetaxel and have progressed within 12 months of treatment with either abiraterone or enzalutamide.

Design. The CARD trial was an international, randomized, open-label phase 3 trial conducted across 13 European countries.

Setting and participants. Eligible patients were 18 years of age or older; had metastatic castration-resistant prostate cancer previously treated with docetaxel; and had disease progression during 12 months of treatment with abiraterone or enzalutamide. All patients had histologically proven prostate cancer, castrate levels of serum testosterone, and disease progression, defined by at least 2 new bone lesions or rising prostate-specific antigen (PSA) level. A total of 255 patients underwent randomization between November 2015 and November 2018, with 129 assigned to receive cabazitaxel and 126 patients assigned to receive an ASTI, 58 of whom received abiraterone and 66 of whom received enzalutamide. Patients who had received an ASTI in the setting of castrate-sensitive metastatic prostate cancer were included.

Intervention. Patients were randomized in a 1:1 fashion to receive either cabazitaxel or abiraterone or enzalutamide. Patients receiving cabazitaxel 25 mg/m² intravenously every 3 weeks also received oral prednisone daily and primary prophylactic granulocyte-colony stimulating factor. Patients assigned to receive an ASTI received abiraterone 1000 mg orally daily with prednisone 5 mg twice daily or enzalutamide 160 mg daily. Patients in the ASTI group who had progressed on abiraterone were assigned to enzalutamide, and alternatively, those on enzalutamide were assigned to abiraterone. Patients were treated until 1 of the following occurred: imaging-based disease progression, unacceptable toxicity, or advancing to an alternative therapy.

Main outcome measures. The primary endpoint was imaging-based progression-free survival, which was defined as the time from randomization until objective tumor progression, progression of bone lesions, or death. The secondary endpoints were overall survival, progression-free survival, PSA response, tumor and pain responses, a new symptomatic skeletal event, and safety.

Results. The median follow-up was 9.2 months. Imaging-based disease progression or death from any cause occurred in 95 (73.6%) participants in the cabazitaxel group, as compared to 101 (80.2%) who were assigned to receive an ASTI. The median imaging-based progression-free survival was 8.0 months in the cabazitaxel group and 3.7 months in the abiraterone/enzalutamide group. The median duration of treatment was longer in those receiving cabazitaxel (22 vs 12.5 weeks). The primary reason for treatment discontinuation was disease progression (in 43.7% of patients receiving cabazitaxel and 71% receiving an ASTI) or an adverse event (19.8% and 8.9%, respectively).

The trial’s secondary endpoints demonstrated improved outcomes in the cabazitaxel group compared to the abiraterone/enzalutamide group. There were 70 deaths (54.2%) in the cabazitaxel group and 83 (65.9%) in the ASTI group. Both the median overall survival (13.6 months in the cabazitaxel group and 11 months in the ASTI group) and the median progression-free survival (4.4 months and 2.7 months, respectively) were improved in those who received cabazitaxel. There was a 50% or greater reduction in the PSA level from baseline in 35.7% of the cabazitaxel group and 13.5% of the ASTI group.

Regarding the safety of the agents, the incidence of adverse events was similar in each group (38.9% in the cabazitaxel group and 38.7% in the ASTI group). Treatment discontinuation occurred more frequently in the cabazitaxel group (19.8%) compared to the ASTI group (8.9%). Adverse events of grade 3 or higher occurred more frequently with cabazitaxel; these were asthenia (4% vs 2.4%), diarrhea (3.2% vs 0), peripheral neuropathy (3.2% vs 0 patients), and febrile neutropenia (3.2% vs 0 patients).

Conclusion. Patients who had disease progression within 12 months on an ASTI and had previously been treated for metastatic castration-resistant prostate cancer with docetaxel had longer imaging-based progression-free survival and overall survival when treated with cabazitaxel compared to those treated with an alternative ASTI. Other clinical outcomes, including overall survival and progression-free survival, were also improved in the cabazitaxel group.

Commentary

Four ASTIs are approved for therapy in men with advanced prostate cancer. The next line of therapy following progression on an ASTI, whether to consider second-line androgen targeted inhibitors or proceed to taxane-based chemotherapy, has been unclear. The current CARD trial sought to answer this question and provides evidence that cabazitaxel is the next line of therapy for these patients. The trial’s primary endpoint, imaging-based disease progression, was reported in 73.6% of those who received cabazitaxel and in 80.2% of those who received abiraterone or enzalutamide. Patients treated with cabazitaxel had a longer imaging-based progression-free survival (8.0 months vs 3.7 months) and a longer duration of treatment (22 vs 12.5 weeks).

Because there is clinical evidence of cross-resistance between different ASTIs, the value of sequential therapy has been unclear. Emergence of androgen-receptor splice variant 7 (AR-V7) mutational status in circulating tumor cells is associated with poor outcomes with secondary androgen-signaling inhibitor therapy, and may be an indicator of resistance to subsequent androgen-signaling inhibitors.^1,2 In the PROPHECY trial, the response rates to subsequent androgen targeted therapy in patients with AR-V7 mutations ranged from 30% to 40%.³ Understanding how AR-V7 mutational status may impact such outcomes will certainly help define whether a subgroup exists in whom use of second-line androgen signaling inhibitors may be considered.

The patients enrolled in the current study appear to represent a subgroup of patients with biologically aggressive disease or with inherent resistance to ASTIs. The patients included in this study progressed within 1 year of androgen targeted therapy, which is representative of a more aggressive population of patients who may be hormone insensitive and derive more benefit from chemotherapy. Initial androgen deprivation therapy was given for 13.7 and 12.6 months to the cabazitaxel and enzalutamide/abiraterone arms, respectively, prior to developing castrate-resistant prostate cancer. Patients enrolled in this study also previously received docetaxel, deselecting those who are taxane-resistant and therefore may be less likely to respond to additional taxane-based therapy. Detection of AR-V7 splice variant expression in circulating tumor cells, consideration of biomarker data, and sensitivity to taxanes may help guide decisions regarding the use of sequential androgen-targeted agents; however, there has been no clear data to guide such an approach. It is also important to consider that, because this is a European study, the approved dose given in this trial was 25 mg/m². The PROSELICA trial previously demonstrated noninferiority of 20 mg/m² compared with 25 mg/m², with fewer adverse events, which is the dose now utilized in the United States.⁴

The adverse events of grade 3 or greater occurring in the cabazitaxel group should be discussed with patients, including fatigue, diarrhea, peripheral neuropathy, and febrile neutropenia.

The data from the CARD trial provide guidance regarding therapy sequencing in those with advanced prostate cancer after progression on first-line androgen targeted inhibitors and docetaxel; however, further work is needed to understand the universal application of this data in this cohort.

Applications in Clinical Practice

Patients with metastatic castration-resistant prostate cancer who have received docetaxel and progressed on an androgen-signaling inhibitor within 12 months should be considered for cabazitaxel over an alternative androgen-signaling inhibitor. This decision should be based on several factors, including AR-V7 mutational status, duration of androgen deprivation therapy, and hormone and taxane sensitivity in the past. Future studies are likely to incorporate genomic biomarkers rather than clinical criteria alone to make treatment decisions.

–Britni Souther, DO, and Daniel Isaac, DO, MS, Michigan State University, East Lansing, MI

Study Overview

Objective. To evaluate whether the combination of encorafenib plus cetuximab with or without the MEK inhibitor binimetinib would lead to longer overall survival (OS) than standard therapy in patients with metastatic BRAF V600E–mutated colorectal cancer.

Design. Global, multicenter, randomized, open-label, phase 3 trial.

Intervention. Patients were randomized in a 1:1:1 fashion to 1 of 3 groups: triplet-therapy group (encorafenib 300 mg daily, binimetinib 45 mg twice daily, and cetuximab 400 mg/m² of body surface area initially, then 250 mg/m² weekly), doublet-therapy group (encorafenib and cetuximab in same doses and schedule as the triplet-therapy group), and control group (investigators choice of cetuximab and irinotecan or cetuximab and FOLFIRI). The randomization was stratified by performance status and prior irinotecan use. Treatment was given until progression or unacceptable toxicities on a 28-day cycle. No crossover was permitted.

Setting and participants. 665 patients underwent randomization: 224 patients to triplet-therapy, 220 to doublet-therapy, and 221 to the control group. Eligible patients had histologically confirmed metastatic colorectal cancer with a BRAF V600E mutation. Patients all had disease progression after 1 or 2 previous lines of therapy.

Main outcome measures. The primary end point of the study was OS and objective response rate (ORR) in the triplet-therapy group compared with the control group. Secondary endpoints included OS in the doublet-therapy group compared with the control group, as well as progression-free survival (PFS), duration of response (DOR), and safety. Assessments were performed every 6 weeks for the first 24 weeks and then every 12 weeks thereafter.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of data cutoff, the median duration of follow-up was 7.8 months for each group. The median OS was 9 months in the triplet-therapy group and 5.4 months in the control group (hazard ratio [HR] for death, 0.52; 95% confidence interval [CI], 0.39-0.70; P < 0.001). The median OS was 8.4 months for the doublet-therapy group, resulting in a significant reduction in the risk of death compared with the control group (HR, 0.6; 95% CI, 0.45-0.79; P < 0.001). The estimated 6-month survival was 71% for the triplet-therapy group, 65% for the doublet-therapy group, and 47% for the control group. The triplet-therapy group had a higher ORR compared with the control group (26% versus 2%, P < 0.001). The ORR in the doublet-therapy group was also significantly higher than that in the control group (20% versus 2%, P < 0.001). Complete responses were seen in 4% of patients in the triplet-therapy group, 5% of the doublet-therapy group, and no patients in the control group. PFS was significantly longer in both the triplet-therapy and doublet-therapy groups compared with the control group (median PFS: 4.3 months, 4.2 months, 1.5 months, respectively). This translated into a 62% and 60% reduction in the risk for disease progression or death in the triplet-therapy and doublet-therapy groups, respectively, compared to the control group.

The most common adverse event reported in the triplet-therapy group was gastrointestinal (GI) related (diarrhea, nausea, and vomiting), with grade 3 or higher GI toxicity seen in 10% of patients. Skin toxicity in the form of acneiform dermatitis was seen in almost 50% of those in the triplet-therapy arm; however, grade 3 or higher skin toxicity was uncommon (2%). Overall, adverse events grade 3 or higher were observed in 58% of those in the triplet-therapy group, 50% in the doublet-therapy group, and 61% in the control group. Adverse events leading to drug discontinuation occurred in 7% in the triplet-therapy group, 8% in the doublet-therapy group, and 11% in the control group. Three deaths were considered treatment related: 1 in the triplet-therapy group (bowel perforation) and 2 in the control group (anaphylaxis and respiratory failure).

Conclusion. The triplet-combination of encorafenib, binimetinib, and cetuximab as well as the doublet-regimen of encorafenib and cetuximab improved both PFS and OS in patients with metastatic, BRAF V600E–mutated colorectal cancer that has progressed after 1 or 2 lines of therapy.

Commentary

The current interim analysis of the BEACON CRC trial demonstrates improved response rates, PFS, and, importantly, OS with the triplet regimen of encorafenib, binimetinib, and cetuximab in patients with metastatic BRAF V600E–mutated colorectal cancer compared to standard irinotecan-based therapy. Similarly, a doublet-regimen of encorafenib and cetuximab also improved outcomes compared with irinotecan-based chemotherapy, resulting in significantly higher response rates, PFS, and OS.

BRAF mutations are seen in approximately 5% to 15% of colorectal cancers and are more commonly seen in right-sided disease. BRAF-mutated colorectal cancer has a poor prognosis, and the presence of a BRAF mutation is an independent prognostic factor for decreased survival.¹ Previous work to improve outcomes in this subset of patients has been largely disappointing. For example, Kopetz and colleagues have previously shown that single-agent BRAF inhibition with vemurafenib in metastatic BRAF-mutated colorectal cancer did not show meaningful clinical activity.² Preclinical studies have suggested that single-agent BRAF or MEK inhibition alone do not lead to sustained MAPK pathway inhibition. Mechanistically, inhibition of BRAF has been shown to lead to feedback activation of EGFR; thus, inhibition of BRAF alone does not lead to cessation of proliferation.³ In light of this, the combination of EGFR and BRAF inhibition has been an attractive therapeutic strategy. Yaeger and colleagues enrolled 15 patients in a pilot study looking at the efficacy and safety of the BRAF inhibitor vemurafenib and the EGFR antibody panitumumab in patients with BRAF-mutated metastatic colorectal cancer. In this cohort, combined BRAF and EGFR inhibition showed tumor regression in 10 of 12 patients.⁴ This finding was validated in other subsequent studies.⁵

The current study is the first phase 3 trial to validate the efficacy of BRAF, MEK, and EGFR inhibition in patients with BRAF-mutant metastatic colorectal cancer. The results of this study represent a very important step forward in treating this patient cohort that has historically had very poor clinical outcomes. The combination of encorafenib, binimetinib, and cetuximab improved OS by 48% compared with standard irinotecan-based chemotherapy. In light of this, we now have a chemotherapy-free targeted combination that improves survival and likely represents the new standard of care in patients with BRAF-mutated colorectal cancer after progression on 1 or 2 prior lines of therapy. Ongoing trials are being pursued to investigate the efficacy of these combinations in the upfront setting, and the results of these trials are eagerly awaited.

Applications for Clinical Practice

The combination of encorafenib, binimetinib, and cetuximab improved OS in patients with BRAF-mutated metastatic colorectal cancer after progression on 1 or 2 prior lines of therapy. This combination represents a potential new standard of care in this patient population.

–Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate whether the combination of encorafenib plus cetuximab with or without the MEK inhibitor binimetinib would lead to longer overall survival (OS) than standard therapy in patients with metastatic BRAF V600E–mutated colorectal cancer.

Design. Global, multicenter, randomized, open-label, phase 3 trial.

Intervention. Patients were randomized in a 1:1:1 fashion to 1 of 3 groups: triplet-therapy group (encorafenib 300 mg daily, binimetinib 45 mg twice daily, and cetuximab 400 mg/m² of body surface area initially, then 250 mg/m² weekly), doublet-therapy group (encorafenib and cetuximab in same doses and schedule as the triplet-therapy group), and control group (investigators choice of cetuximab and irinotecan or cetuximab and FOLFIRI). The randomization was stratified by performance status and prior irinotecan use. Treatment was given until progression or unacceptable toxicities on a 28-day cycle. No crossover was permitted.

Setting and participants. 665 patients underwent randomization: 224 patients to triplet-therapy, 220 to doublet-therapy, and 221 to the control group. Eligible patients had histologically confirmed metastatic colorectal cancer with a BRAF V600E mutation. Patients all had disease progression after 1 or 2 previous lines of therapy.

Main outcome measures. The primary end point of the study was OS and objective response rate (ORR) in the triplet-therapy group compared with the control group. Secondary endpoints included OS in the doublet-therapy group compared with the control group, as well as progression-free survival (PFS), duration of response (DOR), and safety. Assessments were performed every 6 weeks for the first 24 weeks and then every 12 weeks thereafter.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of data cutoff, the median duration of follow-up was 7.8 months for each group. The median OS was 9 months in the triplet-therapy group and 5.4 months in the control group (hazard ratio [HR] for death, 0.52; 95% confidence interval [CI], 0.39-0.70; P < 0.001). The median OS was 8.4 months for the doublet-therapy group, resulting in a significant reduction in the risk of death compared with the control group (HR, 0.6; 95% CI, 0.45-0.79; P < 0.001). The estimated 6-month survival was 71% for the triplet-therapy group, 65% for the doublet-therapy group, and 47% for the control group. The triplet-therapy group had a higher ORR compared with the control group (26% versus 2%, P < 0.001). The ORR in the doublet-therapy group was also significantly higher than that in the control group (20% versus 2%, P < 0.001). Complete responses were seen in 4% of patients in the triplet-therapy group, 5% of the doublet-therapy group, and no patients in the control group. PFS was significantly longer in both the triplet-therapy and doublet-therapy groups compared with the control group (median PFS: 4.3 months, 4.2 months, 1.5 months, respectively). This translated into a 62% and 60% reduction in the risk for disease progression or death in the triplet-therapy and doublet-therapy groups, respectively, compared to the control group.

The most common adverse event reported in the triplet-therapy group was gastrointestinal (GI) related (diarrhea, nausea, and vomiting), with grade 3 or higher GI toxicity seen in 10% of patients. Skin toxicity in the form of acneiform dermatitis was seen in almost 50% of those in the triplet-therapy arm; however, grade 3 or higher skin toxicity was uncommon (2%). Overall, adverse events grade 3 or higher were observed in 58% of those in the triplet-therapy group, 50% in the doublet-therapy group, and 61% in the control group. Adverse events leading to drug discontinuation occurred in 7% in the triplet-therapy group, 8% in the doublet-therapy group, and 11% in the control group. Three deaths were considered treatment related: 1 in the triplet-therapy group (bowel perforation) and 2 in the control group (anaphylaxis and respiratory failure).

Conclusion. The triplet-combination of encorafenib, binimetinib, and cetuximab as well as the doublet-regimen of encorafenib and cetuximab improved both PFS and OS in patients with metastatic, BRAF V600E–mutated colorectal cancer that has progressed after 1 or 2 lines of therapy.

Commentary

The current interim analysis of the BEACON CRC trial demonstrates improved response rates, PFS, and, importantly, OS with the triplet regimen of encorafenib, binimetinib, and cetuximab in patients with metastatic BRAF V600E–mutated colorectal cancer compared to standard irinotecan-based therapy. Similarly, a doublet-regimen of encorafenib and cetuximab also improved outcomes compared with irinotecan-based chemotherapy, resulting in significantly higher response rates, PFS, and OS.

BRAF mutations are seen in approximately 5% to 15% of colorectal cancers and are more commonly seen in right-sided disease. BRAF-mutated colorectal cancer has a poor prognosis, and the presence of a BRAF mutation is an independent prognostic factor for decreased survival.¹ Previous work to improve outcomes in this subset of patients has been largely disappointing. For example, Kopetz and colleagues have previously shown that single-agent BRAF inhibition with vemurafenib in metastatic BRAF-mutated colorectal cancer did not show meaningful clinical activity.² Preclinical studies have suggested that single-agent BRAF or MEK inhibition alone do not lead to sustained MAPK pathway inhibition. Mechanistically, inhibition of BRAF has been shown to lead to feedback activation of EGFR; thus, inhibition of BRAF alone does not lead to cessation of proliferation.³ In light of this, the combination of EGFR and BRAF inhibition has been an attractive therapeutic strategy. Yaeger and colleagues enrolled 15 patients in a pilot study looking at the efficacy and safety of the BRAF inhibitor vemurafenib and the EGFR antibody panitumumab in patients with BRAF-mutated metastatic colorectal cancer. In this cohort, combined BRAF and EGFR inhibition showed tumor regression in 10 of 12 patients.⁴ This finding was validated in other subsequent studies.⁵

The current study is the first phase 3 trial to validate the efficacy of BRAF, MEK, and EGFR inhibition in patients with BRAF-mutant metastatic colorectal cancer. The results of this study represent a very important step forward in treating this patient cohort that has historically had very poor clinical outcomes. The combination of encorafenib, binimetinib, and cetuximab improved OS by 48% compared with standard irinotecan-based chemotherapy. In light of this, we now have a chemotherapy-free targeted combination that improves survival and likely represents the new standard of care in patients with BRAF-mutated colorectal cancer after progression on 1 or 2 prior lines of therapy. Ongoing trials are being pursued to investigate the efficacy of these combinations in the upfront setting, and the results of these trials are eagerly awaited.

Applications for Clinical Practice

The combination of encorafenib, binimetinib, and cetuximab improved OS in patients with BRAF-mutated metastatic colorectal cancer after progression on 1 or 2 prior lines of therapy. This combination represents a potential new standard of care in this patient population.

–Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate whether the combination of encorafenib plus cetuximab with or without the MEK inhibitor binimetinib would lead to longer overall survival (OS) than standard therapy in patients with metastatic BRAF V600E–mutated colorectal cancer.

Design. Global, multicenter, randomized, open-label, phase 3 trial.

Intervention. Patients were randomized in a 1:1:1 fashion to 1 of 3 groups: triplet-therapy group (encorafenib 300 mg daily, binimetinib 45 mg twice daily, and cetuximab 400 mg/m² of body surface area initially, then 250 mg/m² weekly), doublet-therapy group (encorafenib and cetuximab in same doses and schedule as the triplet-therapy group), and control group (investigators choice of cetuximab and irinotecan or cetuximab and FOLFIRI). The randomization was stratified by performance status and prior irinotecan use. Treatment was given until progression or unacceptable toxicities on a 28-day cycle. No crossover was permitted.

Setting and participants. 665 patients underwent randomization: 224 patients to triplet-therapy, 220 to doublet-therapy, and 221 to the control group. Eligible patients had histologically confirmed metastatic colorectal cancer with a BRAF V600E mutation. Patients all had disease progression after 1 or 2 previous lines of therapy.

Main outcome measures. The primary end point of the study was OS and objective response rate (ORR) in the triplet-therapy group compared with the control group. Secondary endpoints included OS in the doublet-therapy group compared with the control group, as well as progression-free survival (PFS), duration of response (DOR), and safety. Assessments were performed every 6 weeks for the first 24 weeks and then every 12 weeks thereafter.

Results. The baseline characteristics were well balanced between the treatment arms. At the time of data cutoff, the median duration of follow-up was 7.8 months for each group. The median OS was 9 months in the triplet-therapy group and 5.4 months in the control group (hazard ratio [HR] for death, 0.52; 95% confidence interval [CI], 0.39-0.70; P < 0.001). The median OS was 8.4 months for the doublet-therapy group, resulting in a significant reduction in the risk of death compared with the control group (HR, 0.6; 95% CI, 0.45-0.79; P < 0.001). The estimated 6-month survival was 71% for the triplet-therapy group, 65% for the doublet-therapy group, and 47% for the control group. The triplet-therapy group had a higher ORR compared with the control group (26% versus 2%, P < 0.001). The ORR in the doublet-therapy group was also significantly higher than that in the control group (20% versus 2%, P < 0.001). Complete responses were seen in 4% of patients in the triplet-therapy group, 5% of the doublet-therapy group, and no patients in the control group. PFS was significantly longer in both the triplet-therapy and doublet-therapy groups compared with the control group (median PFS: 4.3 months, 4.2 months, 1.5 months, respectively). This translated into a 62% and 60% reduction in the risk for disease progression or death in the triplet-therapy and doublet-therapy groups, respectively, compared to the control group.

The most common adverse event reported in the triplet-therapy group was gastrointestinal (GI) related (diarrhea, nausea, and vomiting), with grade 3 or higher GI toxicity seen in 10% of patients. Skin toxicity in the form of acneiform dermatitis was seen in almost 50% of those in the triplet-therapy arm; however, grade 3 or higher skin toxicity was uncommon (2%). Overall, adverse events grade 3 or higher were observed in 58% of those in the triplet-therapy group, 50% in the doublet-therapy group, and 61% in the control group. Adverse events leading to drug discontinuation occurred in 7% in the triplet-therapy group, 8% in the doublet-therapy group, and 11% in the control group. Three deaths were considered treatment related: 1 in the triplet-therapy group (bowel perforation) and 2 in the control group (anaphylaxis and respiratory failure).

Conclusion. The triplet-combination of encorafenib, binimetinib, and cetuximab as well as the doublet-regimen of encorafenib and cetuximab improved both PFS and OS in patients with metastatic, BRAF V600E–mutated colorectal cancer that has progressed after 1 or 2 lines of therapy.

Commentary

The current interim analysis of the BEACON CRC trial demonstrates improved response rates, PFS, and, importantly, OS with the triplet regimen of encorafenib, binimetinib, and cetuximab in patients with metastatic BRAF V600E–mutated colorectal cancer compared to standard irinotecan-based therapy. Similarly, a doublet-regimen of encorafenib and cetuximab also improved outcomes compared with irinotecan-based chemotherapy, resulting in significantly higher response rates, PFS, and OS.

BRAF mutations are seen in approximately 5% to 15% of colorectal cancers and are more commonly seen in right-sided disease. BRAF-mutated colorectal cancer has a poor prognosis, and the presence of a BRAF mutation is an independent prognostic factor for decreased survival.¹ Previous work to improve outcomes in this subset of patients has been largely disappointing. For example, Kopetz and colleagues have previously shown that single-agent BRAF inhibition with vemurafenib in metastatic BRAF-mutated colorectal cancer did not show meaningful clinical activity.² Preclinical studies have suggested that single-agent BRAF or MEK inhibition alone do not lead to sustained MAPK pathway inhibition. Mechanistically, inhibition of BRAF has been shown to lead to feedback activation of EGFR; thus, inhibition of BRAF alone does not lead to cessation of proliferation.³ In light of this, the combination of EGFR and BRAF inhibition has been an attractive therapeutic strategy. Yaeger and colleagues enrolled 15 patients in a pilot study looking at the efficacy and safety of the BRAF inhibitor vemurafenib and the EGFR antibody panitumumab in patients with BRAF-mutated metastatic colorectal cancer. In this cohort, combined BRAF and EGFR inhibition showed tumor regression in 10 of 12 patients.⁴ This finding was validated in other subsequent studies.⁵

The current study is the first phase 3 trial to validate the efficacy of BRAF, MEK, and EGFR inhibition in patients with BRAF-mutant metastatic colorectal cancer. The results of this study represent a very important step forward in treating this patient cohort that has historically had very poor clinical outcomes. The combination of encorafenib, binimetinib, and cetuximab improved OS by 48% compared with standard irinotecan-based chemotherapy. In light of this, we now have a chemotherapy-free targeted combination that improves survival and likely represents the new standard of care in patients with BRAF-mutated colorectal cancer after progression on 1 or 2 prior lines of therapy. Ongoing trials are being pursued to investigate the efficacy of these combinations in the upfront setting, and the results of these trials are eagerly awaited.

Applications for Clinical Practice

The combination of encorafenib, binimetinib, and cetuximab improved OS in patients with BRAF-mutated metastatic colorectal cancer after progression on 1 or 2 prior lines of therapy. This combination represents a potential new standard of care in this patient population.

–Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of enzalutamide compared with standard first-line testosterone suppression in men with newly diagnosed metastatic, castrate-sensitive prostate cancer.

Design. Multinational, open-label, randomized phase 3 trial.

Setting and participants. 1125 men were randomly assigned to receive enzalutamide (563 patients) or standard care (562 patients) from March 2014 through March 2017. Eligible patients had a histologic diagnosis of prostate adenocarcinoma with metastases documented by conventional imaging with computed tomography (CT) and/or technetium-99 bone scan. Prior use of adjuvant testosterone suppression was allowed for up to 2 years, provided this had been completed at least 12 months prior to enrollment.

Intervention. Patients were randomized in a 1:1 fashion to receive enzalutamide 160 mg daily or nonsteroidal antiandrogen therapy with bicalutamide, nilutamide, or flutamide. All patients received testosterone suppression with goserelin, leuprolide, or degarelix. Therapy was continued until disease progression or intolerable adverse effects occurred. In November 2014 the protocol was amended to allow for early administration of docetaxel 75 mg/m² every 3 weeks for 6 cycles and androgen suppression. Patients were stratified according to having received docetaxel prior to randomization. This amendment was based on evidence of improved survival noted with this combination, and the decision to add docetaxel was up to the treating physician. The randomization was further stratified by disease volume, the use of bone-modifying agents, and comorbidity scores. High-volume disease was defined as the presence of visceral metastases or at least 4 bone lesions, with at least 1 being in the appendicular skeleton.

Main outcome measures. The primary endpoint was overall survival (OS). The secondary endpoints were prostate-specific antigen (PSA) progression-free survival (PFS), clinical PFS, death from any cause, or the last known follow-up PSA. PSA progression was defined as an increase in PSA level from the nadir value by ≥ 25% and by ≥ 2 ng/mL.

Main results. The baseline characteristics were well balanced between the treatment arms. High-volume disease was present in 52% of patients. Early docetaxel was planned in 45% of patients; however, 22 patients in whom docetaxel treatment was planned did not receive it. All 6 cycles of docetaxel were given to 159 patients in the enzalutamide group and 181 patients in the standard-care group. After a median follow-up of 34 months, there were 102 deaths in the enzalutamide group and 143 deaths in the standard-care group, with a hazard ratio (HR) for death of 0.67 (95% confidence interval [CI], 0.52-0.86; P = 0.002). Early docetaxel treatment, volume of disease, and use of bone-modifying agents did not affect this outcome. At 3 years, the OS was 80% in the enzalutamide group and 72% in the standard-care group. The rate of PSA-determined PFS was higher in the enzalutamide group compared with the standard group (3-year event-free survival, 67% and 37%, respectively), with a HR of 0.39 (95% CI, 0.33-0.47; P < 0.001). There were fewer clinical PFS events in the enzalutamide group (167 events vs 320 events), with a HR of 0.40 (95% CI, 0.33-0.49; P < 0.001). Analysis of the stratified subgroups showed the effect on OS was diminished in those with use of bone-modifying agents, those with high-volume disease, and those who received early docetaxel. The clinical PFS benefit was maintained across all subgroups, albeit with a smaller effect in those with high-volume disease and in those with early docetaxel treatment.

Treatment discontinuation for reasons other than progressive disease occurred in 12% of those in the enzalutamide group and 19% of those in the standard-care group. Overall, the adverse events were consistent with the known safety profiles of the treatment regimen. Seizures occurred in 7 patients on enzalutamide and no patients in the standard-care group. Fatigue was more common with enzalutamide.

Conclusion. Enzalutamide treatment was associated with significantly longer PFS and OS compared with standard care in men with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression.

Commentary

The current study shows that the addition of enzalutamide to standard androgen deprivation therapy (ADT) improves OS and PFS in men with newly diagnosed metastatic, hormone-sensitive prostate cancer. Until recently, antiandrogen therapy had been the standard of care for these men; however, with the advent of novel antiandrogen agents, outcomes in men with metastatic prostate cancer in both the androgen-sensitive and castrate-resistant settings have steadily improved.^1-5 In the castrate-resistant setting, enzalutamide has previously been shown to improve survival in chemotherapy-naïve patients and those previously exposed to docetaxel chemotherapy.^5-7 Similarly, in the hormone-sensitive setting the combination of ADT with either abiraterone or chemotherapy has been shown to improve outcomes. In the phase 3 LATITUDE and STAMPEDE trials, the combination of abiraterone plus prednisone and ADT resulted in a 30% and 37% improvement in OS, respectively.^1,2 Six cycles of docetaxel in combination with ADT also resulted in a 37% increase in OS in those with high-volume metastatic disease.³

The current study adds to the growing body of literature suggesting that combination therapy in the upfront, hormone-sensitive setting improves outcomes. In the CHAARTED trial, the combination of docetaxel and ADT improved survival in men with high-volume disease, but it did not seem to benefit those with lower-volume disease.³ However, the current data suggests a survival advantage with enzalutamide with low-volume disease as well. The use of docetaxel was similar between the 2 groups, and this suggests that the benefits of enzalutamide cannot be attributed to early integration of docetaxel. It is important to note that the subgroup analysis of those who received early docetaxel showed that these patients did not experience the same survival benefit as those who did not receive docetaxel. However, this trial was not powered for this analysis, and thus it should be interpreted with caution. PFS benefit was maintained across those who received and did not receive early docetaxel. Also worth noting is the increased docetaxel-related toxicity in the combination docetaxel and enzalutamide arm of this study. The neurological toxicity of enzalutamide was again noted, with 7 seizure events documented in this study.

Because this report on the ENZAMET study is an interim analysis, it will be important to follow these outcomes as the data set matures to ensure these effects are maintained over time. Additionally, it will be important to see what implications the addition of enzalutamide have on quality of life measures, as these data have not yet been published.

Applications for Clinical Practice

The ENZAMET study provides evidence that in men with metastatic, hormone-sensitive prostate cancer receiving ADT, the addition of enzalutamide improves PFS and OS. In men who received early docetaxel, enzalutamide was associated with increased toxicity. Additionally, while PFS was improved in men who received enzalutamide and docetaxel, OS was not improved. The neurologic toxicities of enzalutamide should be considered, particularly in those with a prior history of seizure disorders. Based on these data, enzalutamide in combination with ADT represents a reasonable treatment option in men with metastatic, hormone-sensitive prostate cancer.

—Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of enzalutamide compared with standard first-line testosterone suppression in men with newly diagnosed metastatic, castrate-sensitive prostate cancer.

Design. Multinational, open-label, randomized phase 3 trial.

Setting and participants. 1125 men were randomly assigned to receive enzalutamide (563 patients) or standard care (562 patients) from March 2014 through March 2017. Eligible patients had a histologic diagnosis of prostate adenocarcinoma with metastases documented by conventional imaging with computed tomography (CT) and/or technetium-99 bone scan. Prior use of adjuvant testosterone suppression was allowed for up to 2 years, provided this had been completed at least 12 months prior to enrollment.

Intervention. Patients were randomized in a 1:1 fashion to receive enzalutamide 160 mg daily or nonsteroidal antiandrogen therapy with bicalutamide, nilutamide, or flutamide. All patients received testosterone suppression with goserelin, leuprolide, or degarelix. Therapy was continued until disease progression or intolerable adverse effects occurred. In November 2014 the protocol was amended to allow for early administration of docetaxel 75 mg/m² every 3 weeks for 6 cycles and androgen suppression. Patients were stratified according to having received docetaxel prior to randomization. This amendment was based on evidence of improved survival noted with this combination, and the decision to add docetaxel was up to the treating physician. The randomization was further stratified by disease volume, the use of bone-modifying agents, and comorbidity scores. High-volume disease was defined as the presence of visceral metastases or at least 4 bone lesions, with at least 1 being in the appendicular skeleton.

Main outcome measures. The primary endpoint was overall survival (OS). The secondary endpoints were prostate-specific antigen (PSA) progression-free survival (PFS), clinical PFS, death from any cause, or the last known follow-up PSA. PSA progression was defined as an increase in PSA level from the nadir value by ≥ 25% and by ≥ 2 ng/mL.

Main results. The baseline characteristics were well balanced between the treatment arms. High-volume disease was present in 52% of patients. Early docetaxel was planned in 45% of patients; however, 22 patients in whom docetaxel treatment was planned did not receive it. All 6 cycles of docetaxel were given to 159 patients in the enzalutamide group and 181 patients in the standard-care group. After a median follow-up of 34 months, there were 102 deaths in the enzalutamide group and 143 deaths in the standard-care group, with a hazard ratio (HR) for death of 0.67 (95% confidence interval [CI], 0.52-0.86; P = 0.002). Early docetaxel treatment, volume of disease, and use of bone-modifying agents did not affect this outcome. At 3 years, the OS was 80% in the enzalutamide group and 72% in the standard-care group. The rate of PSA-determined PFS was higher in the enzalutamide group compared with the standard group (3-year event-free survival, 67% and 37%, respectively), with a HR of 0.39 (95% CI, 0.33-0.47; P < 0.001). There were fewer clinical PFS events in the enzalutamide group (167 events vs 320 events), with a HR of 0.40 (95% CI, 0.33-0.49; P < 0.001). Analysis of the stratified subgroups showed the effect on OS was diminished in those with use of bone-modifying agents, those with high-volume disease, and those who received early docetaxel. The clinical PFS benefit was maintained across all subgroups, albeit with a smaller effect in those with high-volume disease and in those with early docetaxel treatment.

Treatment discontinuation for reasons other than progressive disease occurred in 12% of those in the enzalutamide group and 19% of those in the standard-care group. Overall, the adverse events were consistent with the known safety profiles of the treatment regimen. Seizures occurred in 7 patients on enzalutamide and no patients in the standard-care group. Fatigue was more common with enzalutamide.

Conclusion. Enzalutamide treatment was associated with significantly longer PFS and OS compared with standard care in men with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression.

Commentary

The current study shows that the addition of enzalutamide to standard androgen deprivation therapy (ADT) improves OS and PFS in men with newly diagnosed metastatic, hormone-sensitive prostate cancer. Until recently, antiandrogen therapy had been the standard of care for these men; however, with the advent of novel antiandrogen agents, outcomes in men with metastatic prostate cancer in both the androgen-sensitive and castrate-resistant settings have steadily improved.^1-5 In the castrate-resistant setting, enzalutamide has previously been shown to improve survival in chemotherapy-naïve patients and those previously exposed to docetaxel chemotherapy.^5-7 Similarly, in the hormone-sensitive setting the combination of ADT with either abiraterone or chemotherapy has been shown to improve outcomes. In the phase 3 LATITUDE and STAMPEDE trials, the combination of abiraterone plus prednisone and ADT resulted in a 30% and 37% improvement in OS, respectively.^1,2 Six cycles of docetaxel in combination with ADT also resulted in a 37% increase in OS in those with high-volume metastatic disease.³

The current study adds to the growing body of literature suggesting that combination therapy in the upfront, hormone-sensitive setting improves outcomes. In the CHAARTED trial, the combination of docetaxel and ADT improved survival in men with high-volume disease, but it did not seem to benefit those with lower-volume disease.³ However, the current data suggests a survival advantage with enzalutamide with low-volume disease as well. The use of docetaxel was similar between the 2 groups, and this suggests that the benefits of enzalutamide cannot be attributed to early integration of docetaxel. It is important to note that the subgroup analysis of those who received early docetaxel showed that these patients did not experience the same survival benefit as those who did not receive docetaxel. However, this trial was not powered for this analysis, and thus it should be interpreted with caution. PFS benefit was maintained across those who received and did not receive early docetaxel. Also worth noting is the increased docetaxel-related toxicity in the combination docetaxel and enzalutamide arm of this study. The neurological toxicity of enzalutamide was again noted, with 7 seizure events documented in this study.

Because this report on the ENZAMET study is an interim analysis, it will be important to follow these outcomes as the data set matures to ensure these effects are maintained over time. Additionally, it will be important to see what implications the addition of enzalutamide have on quality of life measures, as these data have not yet been published.

Applications for Clinical Practice

The ENZAMET study provides evidence that in men with metastatic, hormone-sensitive prostate cancer receiving ADT, the addition of enzalutamide improves PFS and OS. In men who received early docetaxel, enzalutamide was associated with increased toxicity. Additionally, while PFS was improved in men who received enzalutamide and docetaxel, OS was not improved. The neurologic toxicities of enzalutamide should be considered, particularly in those with a prior history of seizure disorders. Based on these data, enzalutamide in combination with ADT represents a reasonable treatment option in men with metastatic, hormone-sensitive prostate cancer.

—Daniel Isaac, DO, MS

Study Overview

Objective. To evaluate the efficacy of enzalutamide compared with standard first-line testosterone suppression in men with newly diagnosed metastatic, castrate-sensitive prostate cancer.

Design. Multinational, open-label, randomized phase 3 trial.

Setting and participants. 1125 men were randomly assigned to receive enzalutamide (563 patients) or standard care (562 patients) from March 2014 through March 2017. Eligible patients had a histologic diagnosis of prostate adenocarcinoma with metastases documented by conventional imaging with computed tomography (CT) and/or technetium-99 bone scan. Prior use of adjuvant testosterone suppression was allowed for up to 2 years, provided this had been completed at least 12 months prior to enrollment.

Intervention. Patients were randomized in a 1:1 fashion to receive enzalutamide 160 mg daily or nonsteroidal antiandrogen therapy with bicalutamide, nilutamide, or flutamide. All patients received testosterone suppression with goserelin, leuprolide, or degarelix. Therapy was continued until disease progression or intolerable adverse effects occurred. In November 2014 the protocol was amended to allow for early administration of docetaxel 75 mg/m² every 3 weeks for 6 cycles and androgen suppression. Patients were stratified according to having received docetaxel prior to randomization. This amendment was based on evidence of improved survival noted with this combination, and the decision to add docetaxel was up to the treating physician. The randomization was further stratified by disease volume, the use of bone-modifying agents, and comorbidity scores. High-volume disease was defined as the presence of visceral metastases or at least 4 bone lesions, with at least 1 being in the appendicular skeleton.

Main outcome measures. The primary endpoint was overall survival (OS). The secondary endpoints were prostate-specific antigen (PSA) progression-free survival (PFS), clinical PFS, death from any cause, or the last known follow-up PSA. PSA progression was defined as an increase in PSA level from the nadir value by ≥ 25% and by ≥ 2 ng/mL.

Main results. The baseline characteristics were well balanced between the treatment arms. High-volume disease was present in 52% of patients. Early docetaxel was planned in 45% of patients; however, 22 patients in whom docetaxel treatment was planned did not receive it. All 6 cycles of docetaxel were given to 159 patients in the enzalutamide group and 181 patients in the standard-care group. After a median follow-up of 34 months, there were 102 deaths in the enzalutamide group and 143 deaths in the standard-care group, with a hazard ratio (HR) for death of 0.67 (95% confidence interval [CI], 0.52-0.86; P = 0.002). Early docetaxel treatment, volume of disease, and use of bone-modifying agents did not affect this outcome. At 3 years, the OS was 80% in the enzalutamide group and 72% in the standard-care group. The rate of PSA-determined PFS was higher in the enzalutamide group compared with the standard group (3-year event-free survival, 67% and 37%, respectively), with a HR of 0.39 (95% CI, 0.33-0.47; P < 0.001). There were fewer clinical PFS events in the enzalutamide group (167 events vs 320 events), with a HR of 0.40 (95% CI, 0.33-0.49; P < 0.001). Analysis of the stratified subgroups showed the effect on OS was diminished in those with use of bone-modifying agents, those with high-volume disease, and those who received early docetaxel. The clinical PFS benefit was maintained across all subgroups, albeit with a smaller effect in those with high-volume disease and in those with early docetaxel treatment.

Treatment discontinuation for reasons other than progressive disease occurred in 12% of those in the enzalutamide group and 19% of those in the standard-care group. Overall, the adverse events were consistent with the known safety profiles of the treatment regimen. Seizures occurred in 7 patients on enzalutamide and no patients in the standard-care group. Fatigue was more common with enzalutamide.

Conclusion. Enzalutamide treatment was associated with significantly longer PFS and OS compared with standard care in men with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression.

Commentary

The current study shows that the addition of enzalutamide to standard androgen deprivation therapy (ADT) improves OS and PFS in men with newly diagnosed metastatic, hormone-sensitive prostate cancer. Until recently, antiandrogen therapy had been the standard of care for these men; however, with the advent of novel antiandrogen agents, outcomes in men with metastatic prostate cancer in both the androgen-sensitive and castrate-resistant settings have steadily improved.^1-5 In the castrate-resistant setting, enzalutamide has previously been shown to improve survival in chemotherapy-naïve patients and those previously exposed to docetaxel chemotherapy.^5-7 Similarly, in the hormone-sensitive setting the combination of ADT with either abiraterone or chemotherapy has been shown to improve outcomes. In the phase 3 LATITUDE and STAMPEDE trials, the combination of abiraterone plus prednisone and ADT resulted in a 30% and 37% improvement in OS, respectively.^1,2 Six cycles of docetaxel in combination with ADT also resulted in a 37% increase in OS in those with high-volume metastatic disease.³

The current study adds to the growing body of literature suggesting that combination therapy in the upfront, hormone-sensitive setting improves outcomes. In the CHAARTED trial, the combination of docetaxel and ADT improved survival in men with high-volume disease, but it did not seem to benefit those with lower-volume disease.³ However, the current data suggests a survival advantage with enzalutamide with low-volume disease as well. The use of docetaxel was similar between the 2 groups, and this suggests that the benefits of enzalutamide cannot be attributed to early integration of docetaxel. It is important to note that the subgroup analysis of those who received early docetaxel showed that these patients did not experience the same survival benefit as those who did not receive docetaxel. However, this trial was not powered for this analysis, and thus it should be interpreted with caution. PFS benefit was maintained across those who received and did not receive early docetaxel. Also worth noting is the increased docetaxel-related toxicity in the combination docetaxel and enzalutamide arm of this study. The neurological toxicity of enzalutamide was again noted, with 7 seizure events documented in this study.

Because this report on the ENZAMET study is an interim analysis, it will be important to follow these outcomes as the data set matures to ensure these effects are maintained over time. Additionally, it will be important to see what implications the addition of enzalutamide have on quality of life measures, as these data have not yet been published.

Applications for Clinical Practice

The ENZAMET study provides evidence that in men with metastatic, hormone-sensitive prostate cancer receiving ADT, the addition of enzalutamide improves PFS and OS. In men who received early docetaxel, enzalutamide was associated with increased toxicity. Additionally, while PFS was improved in men who received enzalutamide and docetaxel, OS was not improved. The neurologic toxicities of enzalutamide should be considered, particularly in those with a prior history of seizure disorders. Based on these data, enzalutamide in combination with ADT represents a reasonable treatment option in men with metastatic, hormone-sensitive prostate cancer.

—Daniel Isaac, DO, MS