Completing up to a year of pembrolizumab immunotherapy after surgical resection of stage IIB or IIC melanoma decreases patients’ risk for disease recurrence or death by 35%, according to study findings presented at the European Society for Medical Oncology 2021 annual meeting. The new findings led the U.S. Food and Drug Administration to expand its approval of pembrolizumab to use as adjuvant therapy in both adults and children aged 12 and older with early-stage melanoma.

In the phase III double-blind trial, researchers randomized 976 patients to receive either pembrolizumab (n = 487) or placebo (n = 489). After 14.4 months of follow-up, only 11.1% of patients receiving pembrolizumab had disease recurrence compared to 16.8% with placebo, and the 12-month recurrence-free survival rate was 90.5% versus 83.1% with pembrolizumab and placebo, respectively.

Grade 3 or higher drug-related adverse events occurred in 16.1% and 4.3% of patients receiving pembrolizumab and placebo, respectively, and 74 patients discontinued pembrolizumab subsequently. Immune-related adverse events, mostly grade 1 or 2, occurred in 36.2% of patients who received pembrolizumab, most commonly hypothyroidism (15.7%) and hyperthyroidism (10.4%).

Additional research is needed to identify optimal dose frequency and duration in the early-stage setting, and longer follow-up from the current study will help scientists understand the overall survival benefit. However, “these results are set to substantially change the population of melanoma patients who get treated in the adjuvant setting,” the researchers said.

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