OBJECTIVES: The aim of these analyses was to assess predictors of health-related quality of life over time to estimate utilities for patients with treatment-naïve advanced melanoma in the randomized Checkmate 067 trial comparing nivolumab + ipilimumab, nivolumab monotherapy, and ipilimumab monotherapy for use in a cost-effectiveness model (CEM). METHODS: The EQ-5D was administered at baseline and every 6 weeks in Checkmate 067 and was used to generate index utility scores using the UK time trade off (TTO) method. Covariates were based on a combination of prior analyses of large trial datasets, including patient demographic and clinical characteristics, quantitative metrics of fit, qualitative/clinical plausibility, and relevance to the CEM. Several longitudinal mixed linear models were explored using different covariate sets. RESULTS: This analysis included 916 patients and 6882 visits where the EQ-5D was administered. Mean baseline utility score was 0.774 for nivolumab + ipilimumab patients, 0.779 for nivolumab patients, 0.773 for ipilimumab patients, and 0.775 across all patients. The final model selected included baseline utility (to adjust for imbalance between treatment arms), progression status (pre/post), and treatment arm. Parameter estimates in the model were 0.477 for baseline utility (P<0.001), -0.033 for progression status (P<0.001), and -0.032 (P=0.026) and -0.034 (P=0.016) for ipilimumab and nivolumab + ipilimumab (vs. nivolumab), respectively. When implemented in the CEM, the utility estimate for the pre-progression and post-progression states were 0.795 and 0.762, respectively (applying nivolumab as the reference treatment arm). CONCLUSIONS: Results showed that baseline utility, progression, and treatment are predictors of utility over time, which is consistent with prior work in other nivolumab monotherapy and ipilimumab monotherapy trials. As data mature, these analyses will be replicated in this and other nivolumab trials.