Pembrolizumab vs Placebo as Adjuvant Therapy for High-Risk Stage II Melanoma: Long-Term Follow-Up, Rechallenge, and Crossover in KEYNOTE-716
Summary. Adjuvant therapy with pembrolizumab or nivolumab is the standard treatment for stage IIB or higher melanoma. This analysis presents updated data from the KEYNOTE-716 study, including the outcomes of re-treatment and crossover to pembrolizumab in patients who previously received a placebo. The study involved 976 patients aged 12 years and older with resected melanoma, who were randomly assigned to either the pembrolizumab group or the placebo group. With a median follow-up of 52.8 months, pembrolizumab use was associated with better recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) compared to placebo: 71% vs 58% for RFS and 81% vs 70% for DMFS, respectively. The median progression-free survival/recurrence-free survival 2 (PFS/RFS2) was not reached in either group (hazard ratio (HR) 0.75; 95% confidence interval (CI): 0.56–1.01). Among participants, 9 patients received re-treatment, and 71 patients switched to pembrolizumab after placebo. In the re-treatment group, no cases of recurrence were observed among patients with resectable melanoma, whereas among those who switched to pembrolizumab, 41% experienced recurrences. In patients with unresectable melanoma, the objective response rate to pembrolizumab was 0% in the re-treatment group and 43% in the crossover group. The safety profile was consistent with previous findings: adverse events (AEs) occurred in 67% of re-treated patients and in 61% of those who switched to pembrolizumab. The updated KEYNOTE-716 analysis confirms the efficacy of adjuvant pembrolizumab therapy for stage IIB/IIC melanoma after surgery, with pembrolizumab contributing to extended RFS and DMFS, showing positive PFS/RFS2 dynamics and maintaining a stable safety profile.
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