Eggermont AMM, et al. - Authors gauged the efficacy of programmed death 1 (PD-1) inhibitor pembrolizumab as an adjuvant therapy in patients with resected, high-risk stage III melanoma. Considerably longer recurrence-free survival was attained through the administration of 200 mg of pembrolizumab every 3 weeks for up to 1 year as an adjuvant therapy for high-risk stage III melanoma compared to placebo. It did not give rise to any new toxic effects.

Methods

• Randomization was performed of patients with completely resected stage III melanoma (with stratification according to cancer stage and geographic region) to receive 200 mg of pembrolizumab (514 patients) or placebo (505 patients) intravenously every 3 weeks for a total of 18 doses (approximately 1 year) or until disease recurrence or unacceptable toxic effects occurred.
• The primary end points included recurrence-free survival in the overall intention-to-treat population and in the subgroup of patients with cancer that was positive for the PD-1 ligand (PD-L1).
• Safety was also assessed.

Results

• It was illustrated that pembrolizumab correlated with considerably longer recurrence-free survival at a median follow-up of 15 months, than placebo in the overall intention-to-treat population (1-year rate of recurrence-free survival, 75.4% [95% confidence interval {CI}, 71.3 to 78.9] vs. 61.0% [95% CI, 56.5 to 65.1]; hazard ratio for recurrence or death, 0.57; 98.4% CI, 0.43 to 0.74; P < 0.001) and in the subgroup of 853 patients with PD-L1-positive tumors (1-year rate of recurrence-free survival, 77.1% [95% CI, 72.7 to 80.9] in the pembrolizumab group and 62.6% [95% CI, 57.7 to 67.0] in the placebo group; hazard ratio, 0.54; 95% CI, 0.42 to 0.69; P < 0.001).
• Findings disclosed that adverse events of grades 3 to 5 associated with the trial regimen were found in 14.7% of the patients in the pembrolizumab group and in 3.4% of patients in the placebo group.
• In the pembrolizumab group, 1 treatment-related death was reported due to myositis.