Surgical Outcomes After Neoadjuvant Pembrolizumab Plus Chemotherapy for Triple-Negative Breast Cancer: Results from the Randomized, Placebo-Controlled Phase 3 KEYNOTE-522 Study

We prospectively evaluated surgical outcomes following neoadjuvant pembrolizumab or placebo added to neoadjuvant chemotherapy among participants with early-stage triple-negative breast cancer (TNBC) in the phase 3 KEYNOTE-522 study. After definitive surgery, participants received adjuvant pembrolizumab/placebo Q3W for 9 cycles. Surgery type and timing, nodal status postsurgery, and adverse events within 30 days following surgery were recorded. Among 1,174 randomized participants (pembrolizumab plus chemotherapy, n = 784; placebo plus chemotherapy, n = 390), similar proportions underwent breast-conserving surgery (45.2% vs. 45.6%) and mastectomy (44.0% vs. 42.6%). The only AE occurring in ≥5% of participants between 0 and 30 days postsurgery was procedural pain (7.0% vs. 5.8%). The rate of pathological complete nodal response at surgery was 76.7% in the pembrolizumab plus chemotherapy group versus 69.9% in the placebo plus chemotherapy group. These findings show that adding neoadjuvant pembrolizumab to chemotherapy had no adverse impact on surgical outcomes (including type, timing, and safety).