“The 30% reduction in the risk of distant metastasis, and 34% reduction in the risk of death suggests that avelumab may have a role in early triple negative breast cancer patients at high risk of relapse after primary surgery or with invasive residual disease after neoadjuvant chemotherapy,” Pierfranco Conte, MD, from the department of surgery, oncology, and gastroenterology at the University of Padua, Italy, reported at the annual meeting of the American Society of Clinical Oncology.
A-BRAVE is the first randomized phase 3 trial patients with TNBC, treated with adjuvant avelumab, explained Dr. Conte. “Neoadjuvant chemotherapy is recommended for stage cT1c or larger, or cN+ disease. However, in case of invasive residual disease at surgery, prognosis is still very poor.”
TNBC is more immunogenic compared with other breast cancer subtypes, suggesting a role for immune checkpoint inhibitors such as avelumab in this setting, he said.
A-BRAVE Methods and Results
The trial enrolled 477 patients, median age 51 years, between June 2016 and October 2020, after their disease had progressed following initial treatment. There were two strata of patients: those who had received upfront surgery and then adjuvant chemotherapy before disease progression (stratum A, 18%); and those who received neoadjuvant chemotherapy, surgery, and then adjuvant chemo, but still had residual disease (stratum B, 82%).
Patients were randomized to either observation (n = 239) or treatment with avelumab (n = 238), at a dose of 10 mg/kg every 2 weeks for one year.
At a median follow-up of 52.1 months, avelumab did not show an advantage for the primary endpoint of 3-year disease-free survival (DFS), with 68.3% of treated patients meeting this endpoint, compared to 63.2% of observed patients (hazard ratio [HR 0.81, P = .172].
However, the treatment did show statistically significant benefits for the secondary 3-year OS endpoint (84.8% vs 76.3%, HR 0.66, P = .035).
“Trying to understand why we did observe a greater benefit with avelumab in overall survival compared to disease-free survival, we also made a post-hoc exploratory analysis on distant disease-free survival,” explained Dr. Conte.
There was a statistically significant 3-year distant disease-free survival (DDFS) benefit for treated patients compared with controls (75.4% vs 67.9%, HR 0.7, P = .0277), translating to a 30% reduction in the risk of distant metastasis, he noted.
Findings Are ‘Hypothesis-Generating’
The results are “hypothesis-generating at this point,” Alexandra Thomas, MD, a breast medical oncologist who was not involved in the research, said in an interview. “These results suggest that the story on how to best utilize checkpoint blockade as adjuvant therapy in triple negative breast cancer may not yet be fully written.”
She emphasized the study did not meet its primary endpoint, “though the results for secondary endpoints OS and the exploratory endpoint DDFS are intriguing.
“A-BRAVE is a smaller study, especially relative to Impassion030 (ALEXANDRA), which enrolled over 2,000 patients,” she explained. “It is notable that avelumab has slightly different properties than atezolizumab, which was used in Impassion030.”
“Avelumab is also a weak PD-L2 inhibitor. Could this be important? Notably, today most patients with clinical stage II-III triple negative breast cancer will receive pembrolizumab as per KEYNOTE-522, so the potential for clinical impact is greatly reduced,” added Dr. Thomas, professor and assistant director in the department of internal medicine at Duke Cancer Institute, in Durham, North Carolina.
SWOG1814, which has not been reported yet, “also looks at pembrolizumab in patients with residual disease post neoadjuvant chemotherapy and will provide further important information on in this space,” she said.
Merck KGaA funded the study.
Dr. Conte disclosed consulting or advisory roles with Daiichi Sankyo/Lilly, Gilead Sciences, Reveal Genomics; a HER2Dx patient; and providing expert testimony for AstraZeneca.
Dr. Thomas disclosed research grants from Sanofi and Merck.