Final analysis of a randomised trial comparing pembrolizumab versus investigator-choice chemotherapy for ipilimumab-refractory advanced melanoma.

AIM: To evaluate the protocol-specified final analysis of overall survival (OS) in the KEYNOTE-002 study (NCT01704287) of pembrolizumab versus chemotherapy in patients with ipilimumab-refractory, advanced melanoma.

METHODS: In this randomised, phase II study, eligible patients had advanced melanoma with documented progression after two or more ipilimumab doses, previous BRAF or MEK inhibitor or both, if BRAFV600 mutant-positive. Patients were randomised to pembrolizumab 2 mg/kg or 10 mg/kg every 3 weeks or investigator-choice chemotherapy. Crossover to pembrolizumab was allowed following progression on chemotherapy. The protocol-specified final OS was performed in the intent-to-treat population. Survival was positive if p < 0.01 in one pembrolizumab arm.

RESULTS: A total of 180 patients were randomised to pembrolizumab 2 mg/kg, 181 to pembrolizumab 10 mg/kg and 179 to chemotherapy. At a median follow-up of 28 months (range 24.1-35.5), 368 patients died and 98 (55%) crossed over to pembrolizumab. Pembrolizumab 2 mg/kg (hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.67-1.10, p = 0.117) and 10 mg/kg (0.74, 0.57-0.96, p = 0.011) resulted in a non-statistically significant improvement in OS versus chemotherapy; median OS was 13.4 (95% CI 11.0-16.4) and 14.7 (95% CI 11.3-19.5), respectively, versus 11.0 months (95% CI 8.9-13.8), with limited improvement after censoring for crossover. Two-year survival rates were 36% and 38%, versus 30%. Progression-free survival, objective response rate and duration of response improved with pembrolizumab versus chemotherapy, regardless of dose. Grade III-V treatment-related adverse events occurred in 24 (13.5%), 30 (16.8%) and 45 (26.3%) patients, respectively.

CONCLUSION: Improvement in OS with pembrolizumab was not statistically significant at either dose versus chemotherapy.