Commentary: Bendamustine, PET/CT Biomarkers, and BTKi in B-Cell Lymphoma, December 2023

While chimeric antigen receptor (CAR) T-cell therapy has transformed the management of large B-cell lymphoma (LBCL), the majority of patients will ultimately relapse. Efforts to identify predictors of response remain an active area of investigation. One key variable that has been postulated to influence CAR T-cell outcomes is pretreatment bendamustine exposure. Specifically, there has been concern that the lymphodepleting effects of bendamustine could affect T-cell fitness, thus impairing CAR T-cell response. While consensus guidelines have recommended avoiding bendamustine prior to lymphocyte collection, clear data have been lacking. A recent retrospective, multicenter study, which included patients from seven European sites, reported outcomes based on prior bendamustine exposure (Iacoboni et al). In this study, 439 patients with relapsed or refractory LBCL, who received anti-CD19 commercial CAR T-cell therapy after two or more prior treatment lines of therapy, were included. Of these patients, 80 had received prior bendamustine. The authors found that patients recently exposed to bendamustine (< 9 months), vs bendamustine-naive patients, had a significantly lower overall response rate (40% vs 66%; P = .01), overall survival (OS; adjusted hazard ratio [aHR] 2.11; P < .01), and progression-free survival (PFS; aHR 1.82; P < .01) after CAR T-cell infusion. These differences remained significant after inverse probability treatment weighting and propensity score matching. Of note, the authors did not find that the cumulative dose of bendamustine affected outcomes. The authors also identified that, while the risk for cytokine release syndrome and immune effector cell–associated neurotoxicity syndrome was similar between the groups, hematologic toxicity and severe infections were increased in the bendamustine-exposed patients. These data support the recommendation to avoid bendamustine treatment prior to CAR T-cell apheresis. While treatment regimens such as polatuzumab plus bendamustine and rituximab are available in the relapsed setting for LBCL,¹ this regimen should be reserved for post CAR T-cell relapse or for patients not planning to proceed with cellular therapy. The impact of bendamustine exposure on other immune-mediated therapies, such as bispecific antibodies, remains unknown.

Quantitative PET/CT biomarkers have also emerged as predictors of response in diffuse large B-cell lymphoma (DLBCL). A key variable of interest includes total metabolic tumor volume (MTV), which refers to the total volume of tumor with metabolic uptake. While prior studies have demonstrated a correlation of MTV on outcomes following treatment with chemotherapy and CAR T-cell therapy,^2,3 the effect of PET/CT biomarkers on outcomes with other novel agents remains poorly described. A recent study by Alderuccio and colleagues explored the predictive power of PET/CT biomarkers on outcomes in a clinical trial cohort of patients treated with the antibody drug conjugate loncastuximab tesirine. This post hoc analysis reviewed the screening PET/CT scans of 138 patients with relapsed or refractory DLBCL treated with two or more prior systemic therapy lines who received loncastuximab tesirine in LOTIS-2<.⁴ The authors found that an MTV ≥ 96 mL was significantly associated with failure to achieve a complete metabolic response (adjusted odds ratio 5.42; P = .002). Patients with an MTV ≥ 96 mL vs < 96 mL also had a shorter PFS (aHR 2.68; P = .002) and OS (aHR 3.09; P < .0001). In line with prior studies, this analysis demonstrates that baseline MTV has the potential to provide robust risk-stratification and confirms the value of PET/CT biomarkers in DLBCL across treatment types.

This month, the results of the phase 2 TARMAC study, which evaluated treatment with ibrutinib in combination with tisagenlecleucel, were also published. This study included 20 patients with relapsed/refractory mantle cell lymphoma (MCL) who had received one or more prior lines of therapy, including 50% with prior Bruton tyrosine kinase inhibitor (BTKi) exposure. Ibrutinib was initiated prior to leukapheresis and continued through CAR T-cell manufacturing and for at least 6 months post tisagenlecleucel infusion. At 4 months post infusion, the overall and complete response rates were 80% each. Patients without and with prior BTKi exposure had complete response rates of 90% and 70%, respectively. At a median follow-up of 13 months, the estimated 12-month PFS was 75% and OS was 100%. Grades 1-2 and grade 3 cytokine-release syndrome rates were 55% and 20%, respectively, and grade 1-2 immune effector cell–associated neurotoxicity syndrome was seen in 10% of patients. The authors also demonstrated that markers of T-cell exhaustion were decreased in patients with longer ibrutinib exposure prior to leukapheresis. Also of note, the three patients with recent bendamustine therapy did not receive a durable response. Although this is a small study without a control arm, this study provides rationale for the potential advantage of combining BTKi with CAR T-cell therapy, even among patients with prior BTKi exposure.

Additional References

1.       Sehn LH, Hertzberg M, Opat S, et al. Polatuzumab vedotin plus bendamustine and rituximab in relapsed/refractory DLBCL: survival update and new extension cohort data. Blood Adv. 2022;6(2):533-543. doi: 10.1182/bloodadvances.2021005794

2.       Vercellino L, Cottereau AS, Casasnovas O, et al. High total metabolic tumor volume at baseline predicts survival independent of response to therapy. Blood. 2020;135(16):1396-1405. doi: 10.1182/blood.2019003526

3.       Dean EA, Mhaskar RS, Lu H, et al. High metabolic tumor volume is associated with decreased efficacy of axicabtagene ciloleucel in large B-cell lymphoma. Blood Adv. 2020;4(14):3268-3276. doi: 10.1182/bloodadvances.2020001900

4.       Caimi PF, Ai W, Alderuccio JP, et al. Loncastuximab tesirine in relapsed or refractory diffuse large B-cell lymphoma (LOTIS-2): a multicentre, open-label, single-arm, phase 2 trial. Lancet Oncol. 2021;22(6):790-800. doi:

While chimeric antigen receptor (CAR) T-cell therapy has transformed the management of large B-cell lymphoma (LBCL), the majority of patients will ultimately relapse. Efforts to identify predictors of response remain an active area of investigation. One key variable that has been postulated to influence CAR T-cell outcomes is pretreatment bendamustine exposure. Specifically, there has been concern that the lymphodepleting effects of bendamustine could affect T-cell fitness, thus impairing CAR T-cell response. While consensus guidelines have recommended avoiding bendamustine prior to lymphocyte collection, clear data have been lacking. A recent retrospective, multicenter study, which included patients from seven European sites, reported outcomes based on prior bendamustine exposure (Iacoboni et al). In this study, 439 patients with relapsed or refractory LBCL, who received anti-CD19 commercial CAR T-cell therapy after two or more prior treatment lines of therapy, were included. Of these patients, 80 had received prior bendamustine. The authors found that patients recently exposed to bendamustine (< 9 months), vs bendamustine-naive patients, had a significantly lower overall response rate (40% vs 66%; P = .01), overall survival (OS; adjusted hazard ratio [aHR] 2.11; P < .01), and progression-free survival (PFS; aHR 1.82; P < .01) after CAR T-cell infusion. These differences remained significant after inverse probability treatment weighting and propensity score matching. Of note, the authors did not find that the cumulative dose of bendamustine affected outcomes. The authors also identified that, while the risk for cytokine release syndrome and immune effector cell–associated neurotoxicity syndrome was similar between the groups, hematologic toxicity and severe infections were increased in the bendamustine-exposed patients. These data support the recommendation to avoid bendamustine treatment prior to CAR T-cell apheresis. While treatment regimens such as polatuzumab plus bendamustine and rituximab are available in the relapsed setting for LBCL,¹ this regimen should be reserved for post CAR T-cell relapse or for patients not planning to proceed with cellular therapy. The impact of bendamustine exposure on other immune-mediated therapies, such as bispecific antibodies, remains unknown.

Quantitative PET/CT biomarkers have also emerged as predictors of response in diffuse large B-cell lymphoma (DLBCL). A key variable of interest includes total metabolic tumor volume (MTV), which refers to the total volume of tumor with metabolic uptake. While prior studies have demonstrated a correlation of MTV on outcomes following treatment with chemotherapy and CAR T-cell therapy,^2,3 the effect of PET/CT biomarkers on outcomes with other novel agents remains poorly described. A recent study by Alderuccio and colleagues explored the predictive power of PET/CT biomarkers on outcomes in a clinical trial cohort of patients treated with the antibody drug conjugate loncastuximab tesirine. This post hoc analysis reviewed the screening PET/CT scans of 138 patients with relapsed or refractory DLBCL treated with two or more prior systemic therapy lines who received loncastuximab tesirine in LOTIS-2<.⁴ The authors found that an MTV ≥ 96 mL was significantly associated with failure to achieve a complete metabolic response (adjusted odds ratio 5.42; P = .002). Patients with an MTV ≥ 96 mL vs < 96 mL also had a shorter PFS (aHR 2.68; P = .002) and OS (aHR 3.09; P < .0001). In line with prior studies, this analysis demonstrates that baseline MTV has the potential to provide robust risk-stratification and confirms the value of PET/CT biomarkers in DLBCL across treatment types.

This month, the results of the phase 2 TARMAC study, which evaluated treatment with ibrutinib in combination with tisagenlecleucel, were also published. This study included 20 patients with relapsed/refractory mantle cell lymphoma (MCL) who had received one or more prior lines of therapy, including 50% with prior Bruton tyrosine kinase inhibitor (BTKi) exposure. Ibrutinib was initiated prior to leukapheresis and continued through CAR T-cell manufacturing and for at least 6 months post tisagenlecleucel infusion. At 4 months post infusion, the overall and complete response rates were 80% each. Patients without and with prior BTKi exposure had complete response rates of 90% and 70%, respectively. At a median follow-up of 13 months, the estimated 12-month PFS was 75% and OS was 100%. Grades 1-2 and grade 3 cytokine-release syndrome rates were 55% and 20%, respectively, and grade 1-2 immune effector cell–associated neurotoxicity syndrome was seen in 10% of patients. The authors also demonstrated that markers of T-cell exhaustion were decreased in patients with longer ibrutinib exposure prior to leukapheresis. Also of note, the three patients with recent bendamustine therapy did not receive a durable response. Although this is a small study without a control arm, this study provides rationale for the potential advantage of combining BTKi with CAR T-cell therapy, even among patients with prior BTKi exposure.

Additional References

1.       Sehn LH, Hertzberg M, Opat S, et al. Polatuzumab vedotin plus bendamustine and rituximab in relapsed/refractory DLBCL: survival update and new extension cohort data. Blood Adv. 2022;6(2):533-543. doi: 10.1182/bloodadvances.2021005794

2.       Vercellino L, Cottereau AS, Casasnovas O, et al. High total metabolic tumor volume at baseline predicts survival independent of response to therapy. Blood. 2020;135(16):1396-1405. doi: 10.1182/blood.2019003526

3.       Dean EA, Mhaskar RS, Lu H, et al. High metabolic tumor volume is associated with decreased efficacy of axicabtagene ciloleucel in large B-cell lymphoma. Blood Adv. 2020;4(14):3268-3276. doi: 10.1182/bloodadvances.2020001900

4.       Caimi PF, Ai W, Alderuccio JP, et al. Loncastuximab tesirine in relapsed or refractory diffuse large B-cell lymphoma (LOTIS-2): a multicentre, open-label, single-arm, phase 2 trial. Lancet Oncol. 2021;22(6):790-800. doi:

While chimeric antigen receptor (CAR) T-cell therapy has transformed the management of large B-cell lymphoma (LBCL), the majority of patients will ultimately relapse. Efforts to identify predictors of response remain an active area of investigation. One key variable that has been postulated to influence CAR T-cell outcomes is pretreatment bendamustine exposure. Specifically, there has been concern that the lymphodepleting effects of bendamustine could affect T-cell fitness, thus impairing CAR T-cell response. While consensus guidelines have recommended avoiding bendamustine prior to lymphocyte collection, clear data have been lacking. A recent retrospective, multicenter study, which included patients from seven European sites, reported outcomes based on prior bendamustine exposure (Iacoboni et al). In this study, 439 patients with relapsed or refractory LBCL, who received anti-CD19 commercial CAR T-cell therapy after two or more prior treatment lines of therapy, were included. Of these patients, 80 had received prior bendamustine. The authors found that patients recently exposed to bendamustine (< 9 months), vs bendamustine-naive patients, had a significantly lower overall response rate (40% vs 66%; P = .01), overall survival (OS; adjusted hazard ratio [aHR] 2.11; P < .01), and progression-free survival (PFS; aHR 1.82; P < .01) after CAR T-cell infusion. These differences remained significant after inverse probability treatment weighting and propensity score matching. Of note, the authors did not find that the cumulative dose of bendamustine affected outcomes. The authors also identified that, while the risk for cytokine release syndrome and immune effector cell–associated neurotoxicity syndrome was similar between the groups, hematologic toxicity and severe infections were increased in the bendamustine-exposed patients. These data support the recommendation to avoid bendamustine treatment prior to CAR T-cell apheresis. While treatment regimens such as polatuzumab plus bendamustine and rituximab are available in the relapsed setting for LBCL,¹ this regimen should be reserved for post CAR T-cell relapse or for patients not planning to proceed with cellular therapy. The impact of bendamustine exposure on other immune-mediated therapies, such as bispecific antibodies, remains unknown.

Quantitative PET/CT biomarkers have also emerged as predictors of response in diffuse large B-cell lymphoma (DLBCL). A key variable of interest includes total metabolic tumor volume (MTV), which refers to the total volume of tumor with metabolic uptake. While prior studies have demonstrated a correlation of MTV on outcomes following treatment with chemotherapy and CAR T-cell therapy,^2,3 the effect of PET/CT biomarkers on outcomes with other novel agents remains poorly described. A recent study by Alderuccio and colleagues explored the predictive power of PET/CT biomarkers on outcomes in a clinical trial cohort of patients treated with the antibody drug conjugate loncastuximab tesirine. This post hoc analysis reviewed the screening PET/CT scans of 138 patients with relapsed or refractory DLBCL treated with two or more prior systemic therapy lines who received loncastuximab tesirine in LOTIS-2<.⁴ The authors found that an MTV ≥ 96 mL was significantly associated with failure to achieve a complete metabolic response (adjusted odds ratio 5.42; P = .002). Patients with an MTV ≥ 96 mL vs < 96 mL also had a shorter PFS (aHR 2.68; P = .002) and OS (aHR 3.09; P < .0001). In line with prior studies, this analysis demonstrates that baseline MTV has the potential to provide robust risk-stratification and confirms the value of PET/CT biomarkers in DLBCL across treatment types.

This month, the results of the phase 2 TARMAC study, which evaluated treatment with ibrutinib in combination with tisagenlecleucel, were also published. This study included 20 patients with relapsed/refractory mantle cell lymphoma (MCL) who had received one or more prior lines of therapy, including 50% with prior Bruton tyrosine kinase inhibitor (BTKi) exposure. Ibrutinib was initiated prior to leukapheresis and continued through CAR T-cell manufacturing and for at least 6 months post tisagenlecleucel infusion. At 4 months post infusion, the overall and complete response rates were 80% each. Patients without and with prior BTKi exposure had complete response rates of 90% and 70%, respectively. At a median follow-up of 13 months, the estimated 12-month PFS was 75% and OS was 100%. Grades 1-2 and grade 3 cytokine-release syndrome rates were 55% and 20%, respectively, and grade 1-2 immune effector cell–associated neurotoxicity syndrome was seen in 10% of patients. The authors also demonstrated that markers of T-cell exhaustion were decreased in patients with longer ibrutinib exposure prior to leukapheresis. Also of note, the three patients with recent bendamustine therapy did not receive a durable response. Although this is a small study without a control arm, this study provides rationale for the potential advantage of combining BTKi with CAR T-cell therapy, even among patients with prior BTKi exposure.

Additional References

1.       Sehn LH, Hertzberg M, Opat S, et al. Polatuzumab vedotin plus bendamustine and rituximab in relapsed/refractory DLBCL: survival update and new extension cohort data. Blood Adv. 2022;6(2):533-543. doi: 10.1182/bloodadvances.2021005794

2.       Vercellino L, Cottereau AS, Casasnovas O, et al. High total metabolic tumor volume at baseline predicts survival independent of response to therapy. Blood. 2020;135(16):1396-1405. doi: 10.1182/blood.2019003526

3.       Dean EA, Mhaskar RS, Lu H, et al. High metabolic tumor volume is associated with decreased efficacy of axicabtagene ciloleucel in large B-cell lymphoma. Blood Adv. 2020;4(14):3268-3276. doi: 10.1182/bloodadvances.2020001900

4.       Caimi PF, Ai W, Alderuccio JP, et al. Loncastuximab tesirine in relapsed or refractory diffuse large B-cell lymphoma (LOTIS-2): a multicentre, open-label, single-arm, phase 2 trial. Lancet Oncol. 2021;22(6):790-800. doi: