A phase III, randomized, double-blind, multicenter study comparing monotherapy with ipilimumab or gp100 peptide vaccine and the combination in patients with previously treated, unresectable stage III or IV melanoma.

Abstract

4 Background: Ipilimumab, a fully human monoclonal antibody against cytotoxic T-lymphocyte antigen-4, demonstrated activity in advanced melanoma. Gp100 vaccine showed immunological and clinical responses, and enhanced clinical activity when combined with other immunotherapy. This phase III study compared efficacy and safety of ipilimumab or gp100 monotherapy and combination. Methods: Eligible patients (HLA-A*0201+ previously treated adults with unresectable stage III/IV melanoma) were randomized 1:3:1 to ipilimumab (3 mg/kg q3w x 4 doses) + placebo (n=137), ipilimumab + gp100 (peptides 209-217[210M] and 280-288 [288V]; 1mg q3w x 4 doses; n=403), or gp100 + placebo (n=136). There was no maintenance phase. Primary endpoint was comparison of overall survival (OS) between patients who received combination versus gp100 alone; secondary endpoints were all other OS comparisons, best overall response rate (BORR), disease control rate (DCR) to W24, progression-free survival (PFS), and safety. Results: The study demonstrated statistically significant results for all efficacy endpoints (below). Ipilimumab alone or combined with gp100 resulted in a significant improvement in OS with risk reduction of 32-34% compared to gp100. Significant differences in DCR, BORR, and PFS were observed. Adverse events with ipilimumab were consistent with prior studies: generally mild, immune-related, and medically manageable. Conclusions: Ipilimumab is the first agent to improve median and long-term OS in a phase III study of previously treated patients with advanced melanoma. Addition of gp100 vaccine to ipilimumab did not improve outcome. [Table: see text] [Table: see text]