In the phase II SWOG Cancer Research Network S1801 trial reported in The New England Journal of Medicine, Patel et al found that neoadjuvant plus adjuvant pembrolizumab significantly improved event-free survival vs adjuvant pembrolizumab alone in patients with stage IIIB to IV melanoma. The U.S. multicenter open-label trial included 313 patients with resectable stage III or oligometastatic resectable stage IV (M1a, M1b, and M1c) melanoma. Patients were randomly assigned between February 2019 and May 2022 to receive neoadjuvant pembrolizumab at 200 mg every 3 weeks for 3 doses and adjuvant pembrolizumab at 200 mg every 3 weeks for 15 doses or adjuvant pembrolizumab at 200 mg every 3 weeks for 18 doses.
Median follow-up was 14.7 months. Event-free survival events occurred in 25% of patients in the neoadjuvant-adjuvant group vs 42% in the adjuvant-only group. Event-free survival was significantly longer in the neoadjuvant-adjuvant group vs the adjuvant-only group (P = .004). In the landmark analysis, event-free survival at 2 years was 72% (95% confidence interval [CI] = 64%–80%) in the neoadjuvant-adjuvant group vs 49% (95% CI = 41%–59%) in the adjuvant-only group. The investigators concluded, “Among patients with resectable stage III or IV melanoma, event-free survival was significantly longer among those who received pembrolizumab both before and after surgery than among those who received adjuvant pembrolizumab alone. No new toxic effects were identified.”