Pembrolizumab (PD-1) + Neoadjuvant Chemo Cuts Recurrence and Death in Asian Early TNBC Subgroup

Pembrolizumab is an anti–PD-1 checkpoint inhibitor given perioperatively with standard neoadjuvant chemotherapy (taxane + carboplatin → anthracycline/cyclophosphamide) and then continued as adjuvant monotherapy; this updated KEYNOTE-522 (Phase 3, randomized, double-blind; NCT03036488) subgroup analysis focused on participants enrolled in Asia with newly diagnosed high-risk, early-stage TNBC. In Asia (n=216; pembro+chemo n=136 vs placebo+chemo n=80), updated EFS at the March 22, 2024 cutoff showed fewer events with pembrolizumab (13.2% vs 27.5%; HR 0.43 [95% CI 0.23–0.81]) and higher 60-month EFS (87.4% vs 72.1%); OS also favored pembrolizumab (deaths 8.8% vs 20.0%; HR 0.41 [95% CI 0.19–0.86]) with 60-month OS 91.9% vs 81.1%. These outcomes are directionally consistent with the overall KEYNOTE-522 population (5-year EFS 81.2% vs 72.2% [HR 0.65] and 60-month OS 86.6% vs 81.7% [HR 0.66]), which has become the perioperative SOC for this high-risk stage II–III setting; treatment-related AEs led to discontinuation in 14.0% vs 8.9% (pembro vs placebo), underscoring the usual curative-intent tradeoff of improved long-term outcomes with higher immunotherapy-attributed drop-off.