Modelling Survival of Patients Treated with Adjuvant Nivolumab Who Have Melanoma with Lymph Node Involvement or Metastatic Disease After Complete Resection

Introduction Nivolumab demonstrated significant recurrence-free survival (RFS) gains versus ipilimumab in the CheckMate-238 trial, whereas the CA184-029 trial showed superior RFS gains for ipilimumab versus placebo. No head-to-head trial data were available to compare the efficacy of nivolumab to that of observation, so indirect treatment comparisons were required. Additionally, overall survival (OS) data were not available from CheckMate-238, and the clinical pathway for melanoma has changed significantly over the last decade. Four modelling options were developed using different methods and evidence sources to estimate OS and the impact of nivolumab on predicted life-years in the adjuvant setting; however, this article focuses on two primary methods. Methods RFS for nivolumab and observation were informed by a patient-level data meta-regression. The first model was a partitioned survival model, where the parametric OS curve for observation was derived from CA184-029 and nivolumab OS was based on a surrogacy relationship between RFS and OS specific to adjuvant melanoma. The other option used a state-transition model to estimate post-recurrence survival using different data sources. Results The modelling options estimated different OS for both nivolumab and observation but demonstrated at least a 32% increase in life-years gained for nivolumab versus observation. Conclusion This analysis demonstrated the difficulties in modelling within the adjuvant setting. Each model produced different survival projections, showing the need to explore different techniques to address the extent of uncertainty. This also highlighted the importance of understanding the impact of RFS in the long term in a setting where the aim of treatment is to remain disease free.