308 Indirect treatment comparison of nivolumab versus placebo as adjuvant treatment for melanoma

Background We have previously performed indirect treatment comparisons (ITCs) to demonstrate improvements in recurrence-free survival (RFS) and distant metastasis-free survival with nivolumab versus placebo as adjuvant treatment for resected melanoma; however, overall survival (OS) data were not available at the time. Recently, results of the phase 3 CheckMate 238 trial in patients with resected stage IIIB–IIIC/IV melanoma (American Joint Committee on Cancer [AJCC], 7th edition) showed no statistically significant difference in OS between nivolumab and ipilimumab; however, OS events were fewer than expected. In the phase 3 EORTC 18071 trial in patients with resected stage IIIA–IIIC melanoma (AJCC, 6th edition), OS was improved with ipilimumab versus placebo. Here, we provide an update on RFS and an analysis of OS in ITCs of nivolumab and placebo using data from these 2 trials with a common comparator arm: ipilimumab 10 mg/kg. Methods ITCs of nivolumab versus placebo were conducted using 4-year minimum follow-up data from CheckMate 238 (NCT02388906) and 5.3-year median follow-up data from EORTC 18071 (NCT00636168). Bucher ITCs were performed to estimate RFS and OS in the intention-to-treat populations. A sensitivity analysis of OS adjusting for subsequent therapy options was conducted in 2 steps: (1) after controlling for possible confounders and assuming that the only difference was the effect of different subsequent therapies, postrecurrence survival was compared between the 2 ipilimumab arms in each study, and (2) after adjusting for differences in postrecurrence survival, ITCs of nivolumab versus adjusted placebo were performed. Results In these ITC analyses, RFS and OS results with nivolumab suggested an improvement compared with placebo. In the intention-to-treat population, nivolumab was associated with a lower risk of recurrence or death (RFS HR, 0.55; 95% CI, 0.43–0.70) and a lower risk of death (OS HR, 0.62; 95% CI, 0.44–0.88) than placebo. In the sensitivity analysis, a 63% average increase in postrecurrence survival benefit was estimated with ipilimumab in CheckMate 238 compared with ipilimumab in EORTC 18071. After adjusting for this increase in both the ipilimumab and placebo arms in EORTC 18071, nivolumab was associated with a lower risk of death than placebo (OS HR, 0.65; 95% CI, 0.45–0.91), similar to the unadjusted analysis. Conclusions Despite the changing treatment landscape and the increased number of therapeutic options for metastatic melanoma, these ITCs suggested clinically meaningful improvement in RFS and OS with adjuvant nivolumab compared with a wait-and-watch strategy in high-risk patients with resected melanoma. Acknowledgements Writing and editorial assistance were provided by Kakoli Parai, PhD, and Andrea Lockett of Ashfield Healthcare Communications, funded by Bristol-Myers Squibb Company. Trial Registration NCT02388906 (CheckMate 238), NCT00636168 (EORTC 18071)