Q-TWiST analysis comparing ipilimumab/dacarbazine vs placebo/dacarbazine for patients with stage III/IV melanoma

Abstract

Background:

Study CA184024 was a multinational, randomised, double-blind, phase 3 study comparing ipilimumab/dacarbazine (DTIC) vs placebo/DTIC in patients with untreated stage III/IV melanoma, which showed that ipilimumab significantly improves survival in patients with metastatic melanoma. The objective of this analysis was to compare the quality-adjusted survival experience among patients in this trial.

Methods:

Survival time was partitioned into health states: toxicity, time before progression without toxicity, and relapse until death or end of follow-up. Q-TWiST (quality-adjusted time without symptoms of disease or toxicity of treatment) was calculated as the utility-weighted sum of the mean health state durations. Analyses were repeated over extended follow-up periods.

Results:

Based on a combination of trial-based and external utility scores, the Q-TWiST difference in this trial was 0.50 months ( P=0.0326) favoring ipilimumab after 1 year. The Q-TWiST difference was 1.5 months with 2 years of follow-up ( P=0.0091), 2.36 months at 3 years ( P=0.005) and 3.28 months at 4 years ( P=0.0074).

Conclusion:

During the first year of study, there was little difference between groups in quality-adjusted survival. However, after 2, 3 and 4 years follow-up for patients with extended survival, the benefits of IPI+DTIC vs PLA+DTIC for advanced melanoma continue to accrue.