Efficacy and safety of ipilimumab in metastatic melanoma patients surviving more than 2 years following treatment in a phase III trial (MDX010-20)

Abstract

Background: In a phase III trial (ClinicalTrials.gov registration ID: NCT00094653), ipilimumab significantly improved survival versus a vaccine control in pretreated patients with metastatic melanoma. Here, we characterize outcomes of those patients who survived ≥ 2 years.

Methods: Patients were randomized (3 : 1 : 1) to receive ipilimumab 3 mg/kg + gp100 vaccine, ipilimumab 3 mg/kg + placebo, or gp100 vaccine alone. Baseline demographic data, duration of survival, responses, and safety among patients with ≥ 2 years' survival were analyzed.

Results: Among 676 randomized patients, 474 and 259 patients had at least 2 or 3 years of potential follow-up, respectively, and were eligible for analysis. Among these, 94 (20%) and 42 (16%) survived ≥ 2 and ≥ 3 years, respectively. Survival rates at 2 and 3 years were 25% (24 of 95) and 25% (13 of 53) with ipilimumab alone and 19% (54 of 284) and 15% (24 of 156) with ipilimumab plus gp100. Safety among patients with ≥ 2 years' survival was comparable with the overall study population, with the onset of new ipilimumab-related toxic effect (all grades) reported in 6 of 78 (8%) patients.

Conclusions: Ipilimumab results in survival of ≥ 2 years in one-fifth of pretreated patients with 2 years potential follow-up in a phase III trial. New onset, low-grade events starting after administration of the last dose were infrequent.

Trial registration id: NCT00094653.

Keywords: ipilimumab; long-term survivors; melanoma; safety; survival analysis.