SABCS 2021: Neoadjuvant and Adjuvant Pembrolizumab Plus Chemotherapy in Triple-Negative Breast Cancer
Posted: Wednesday, December 8, 2021
Peter Schmid, MD, PhD, of Barts Cancer Institute, Queen Mary University London, United Kingdom, and colleagues conducted the phase III KEYNOTE-522 study, evaluating pembrolizumab versus placebo in patients with triple-negative breast cancer. The primary analysis demonstrated a statistically significant improvement in event-free survival with pembrolizumab plus chemotherapy when followed by adjuvant pembrolizumab. During the 2021 San Antonio Breast Cancer Symposium (SABCS; Abstract GS1-01), their results indicated that the benefit was generally consistent across patient subgroups.
“Event-free survival sensitivity analyses show a robust treatment benefit of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab for previously untreated non-metastatic triple-negative breast cancer,” the investigators concluded.
This study enrolled 1,174 patients with previously untreated, non-metastatic, centrally confirmed triple-negative breast cancer. Participants were randomly assigned to receive pembrolizumab (n = 784) or placebo (n = 390) plus four cycles of paclitaxel plus carboplatin; then they were given four cycles of doxorubicin or epirubicin plus cyclophosphamide. After surgery, individuals were administered nine cycles of pembrolizumab or placebo until unacceptable toxicity or recurrence.
At the data cutoff, the median follow-up was 39.1 months. For all five sensitivity analyses, the event-free survival benefit of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab (15.7%) versus chemotherapy alone (23.8%) was consistent with the primary results in each subgroup. Under alternate censoring rules, event-free survival rates were 14.3% versus 21.5% for those given pembrolizumab versus placebo, respectively. When “new anticancer therapy for metastatic disease” was included as an event, the rates were 15.7% and 23.8%, which were identical to the primary results.
When “positive margin at last surgery” was removed from the definition, rates were 15.6% and 23.1%, and removing “second primary malignancy” decreased the rates to 14.8% and 22.6%. However, when “second breast malignancy” was included, event-free survival rates for individuals given pembrolizumab and placebo were 16.1% and 24.4%, respectively.
Disclosure: For full disclosures of the study authors, visit sabcs.org.