Improved survival with ipilimumab in patients with metastatic melanoma

Abstract

Background: An improvement in overall survival among patients with metastatic melanoma has been an elusive goal. In this phase 3 study, ipilimumab--which blocks cytotoxic T-lymphocyte-associated antigen 4 to potentiate an antitumor T-cell response--administered with or without a glycoprotein 100 (gp100) peptide vaccine was compared with gp100 alone in patients with previously treated metastatic melanoma.

Methods: A total of 676 HLA-A*0201-positive patients with unresectable stage III or IV melanoma, whose disease had progressed while they were receiving therapy for metastatic disease, were randomly assigned, in a 3:1:1 ratio, to receive ipilimumab plus gp100 (403 patients), ipilimumab alone (137), or gp100 alone (136). Ipilimumab, at a dose of 3 mg per kilogram of body weight, was administered with or without gp100 every 3 weeks for up to four treatments (induction). Eligible patients could receive reinduction therapy. The primary end point was overall survival.

Results: The median overall survival was 10.0 months among patients receiving ipilimumab plus gp100, as compared with 6.4 months among patients receiving gp100 alone (hazard ratio for death, 0.68; P<0.001). The median overall survival with ipilimumab alone was 10.1 months (hazard ratio for death in the comparison with gp100 alone, 0.66; P=0.003). No difference in overall survival was detected between the ipilimumab groups (hazard ratio with ipilimumab plus gp100, 1.04; P=0.76). Grade 3 or 4 immune-related adverse events occurred in 10 to 15% of patients treated with ipilimumab and in 3% treated with gp100 alone. There were 14 deaths related to the study drugs (2.1%), and 7 were associated with immune-related adverse events.

Conclusions: Ipilimumab, with or without a gp100 peptide vaccine, as compared with gp100 alone, improved overall survival in patients with previously treated metastatic melanoma. Adverse events can be severe, long-lasting, or both, but most are reversible with appropriate treatment. (Funded by Medarex and Bristol-Myers Squibb; ClinicalTrials.gov number, NCT00094653.)

Figure 1. Kaplan–Meier Curves for Overall Survival and Progression-free Survival in the Intention-to-Treat Population

The median follow-up for overall survival (Panel A) in the ipilimumab (Ipi)-plus-glycoprotein 100 (gp100) group was 21.0 months, and the median overall survival was 10.0 months (95% CI, 8.5 to 11.5); in the ipilimumabalone group, the median follow-up was 27.8 months, and the median overall survival, 10.1 months (95% CI, 8.0 to 13.8); and in the gp100-alone group, the median follow-up was 17.2 months, and the median overall survival, 6.4 months (95% CI, 5.5 to 8.7). The median progression-free survival (Panel B) was 2.76 months (95% CI, 2.73 to 2.79) in the ipilimumab-plus-gp100 group, 2.86 months (95% CI, 2.76 to 3.02) in the ipilimumab-alone group, and 2.76 months (95% CI, 2.73 to 2.83) in the gp100-alone group. The rates of progression-free survival at week 12 were 49.1% (95% CI, 44.1 to 53.9) in the ipilimumab-plus-gp100 group, 57.7% (95% CI, 48.9 to 65.5) in the ipilimumab-alone group, and 48.5% (95% CI, 39.6 to 56.7) in the gp100-alone group.

Figure 2. Subgroup Analyses of Overall Survival

The prespecified analyses of overall survival among subgroups of patients, as defined by baseline demographic characteristics and stratification factors (metastasis [M] stage, classified according to the tumor–node–metastasis [TNM] categorization for melanoma of the American Joint Committee on Cancer; and receipt or nonreceipt of interleukin-2 therapy), showed that hazard ratios were lower than 1 (indicating a lower risk of death) for each subgroup in the ipilimumab (Ipi)-plus-glycoprotein 100 (gp100) group as compared with the gp100-alone group (Panel A) and for each subgroup in the ipilimumab-alone group as compared with the gp100-alone group (Panel B). Hazard ratios were estimated with the use of unstratified Cox proportional-hazards models. Horizontal lines represent 95% confidence intervals. LDH denotes lactate dehydrogenase, and ULN the upper limit of the normal range.