Pembrolizumab, an anti-PD-1 antibody, prolonged progression-free survival and overall survival and had less high-grade toxicity than did ipilimumab in patients with advanced melanoma, a recent study published online in The New England Journal of Medicine has shown.

For this controlled, phase III study, researchers enrolled 834 patients with advanced melanoma and randomly assigned them 1:1:1 to receive pembrolizumab 10mg/kg every 2 weeks, pembrolizumab 10mg/kg every 3 weeks, or ipilimumab 3mg/kg every 3 weeks for four doses.

Results showed that the estimated progression-free survival rates were 47.3%, 46.4%, and 26.5% for pembrolizumab every 2 weeks, pembrolizumab every 3 weeks, and ipilimumab, respectively (HR = 0.58; < 0.001 for both pembrolizumab regimens versus ipilimumab; 95% CI: 0.46-0.72 and 0.47-0.72, respectively).

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Researchers found that estimated 1-year survival rates were 74.1% for pembrolizumab every 2 weeks, 68.4% for pembrolizumab every 3 weeks, and 58.2% for ipilimumab (HR for pembrolizumab every 2 weeks = 0.63; 95% CI: 0.47-0.83; P = 0.0005; HR for pembrolizumab every 3 weeks = 0.69; 95% CI: 0.52-0.90; = 0.0036).

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The study also showed improved response rates with pembrolizumab (every 2 weeks = 33.7%, every 3 weeks = 32.9%) compared with ipilimumab (11.9%) (P < 0.001 for both comparisons).

In regard to safety, 13.3% and 10.1% of those who received pembrolizumab every 2 weeks and every 3 weeks, respectively, experienced grade 3 to 5 treatment-related adverse events compared with 19.9% in the ipilimumab group.

Ipilimumab is currently the standard-of-care treatment for patients with advanced melanoma.


  1. Robert C, Schachter J, Long GV, et al. Pembrolizumab versus ipilimumab in advanced melanoma. N Engl J Med. 2015. [Epub ahead of print]. doi: 10.1056/NEJMoa1503093.