Estimating Long-Term Survivorship Rates Among Patients With Resected Stage III/IV Melanoma: Analyses From CheckMate 238 and European Organization for Research and Treatment of Cancer 18071 Trials

Abstract

PURPOSE Standard-of-care treatments for patients with resected stage III/IV melanoma include the immuno-oncology (IO) agents nivolumab (NIVO) and ipilimumab (IPI). This study used mixture cure models (MCMs) to estimate cure rates among patients treated with NIVO or IPI in the phase III CheckMate 238 (ClinicalTrials.gov identifier: NCT02388906 ) and European Organization for Research and Treatment of Cancer (EORTC) 18071 (ClinicalTrials.gov identifier: NCT00636168 ) trials, and to assess the impact of use of adjuvant immunotherapy on cure rates versus watchful waiting. METHODS MCMs were applied to patient-level recurrence-free survival data from CheckMate 238 and EORTC 18071. Cured patients were assumed to experience no disease recurrence and mortality risks similar to the general population. Uncured patients were at risk of disease recurrence and all-cause death. The survival trend of the cured patients was estimated using life expectancy data for a general population with the same baseline demographic characteristics. A regression model assessed the odds ratios (ORs) of cure across key subgroups on the basis of baseline characteristics of the study populations. RESULTS In CheckMate 238, estimated cure rates were 48.3% (95% CI, 41.8 to 54.9) with NIVO and 38.2% (95% CI, 32.7 to 44.1) with IPI. In EORTC 18071, estimated cure rates were 38.0% (95% CI, 32.1 to 44.2) with IPI and 29.2% (95% CI, 24.4 to 34.6) with placebo. In the indirect comparison of the two trials, the odds of cure were significantly higher with NIVO than with placebo (OR, 2.33 [95% CI, 1.49 to 3.65]). CONCLUSION Analyses involving two large phase III trials investigating adjuvant IO treatment for resected melanoma demonstrate higher cure rates for both NIVO and IPI than placebo, with NIVO providing the highest cure rate. Similar cure rates were estimated for patients treated with IPI in both trials, despite staging and dosing differences.