Abstract
INTRODUCTION: Pembrolizumab was approved in the US as adjuvant treatment of patients with stage IIB or IIC melanoma post-complete resection, based on prolonged recurrence-free survival vs. placebo in the Phase 3 KEYNOTE-716 trial. This study aimed to evaluate the cost-effectiveness of pembrolizumab vs. observation as adjuvant treatment of stage IIB or IIC melanoma from a US health sector perspective. METHODS: A Markov cohort model was constructed to simulate patient transitions among recurrence-free, locoregional recurrence, distant metastasis, and death. Transition probabilities from recurrence-free and locoregional recurrence were estimated via multistate parametric modeling based on patient-level data from an interim analysis (data cutoff date: 04-Jan-2022). Transition probabilities from distant metastasis were based on KEYNOTE-006 data and network meta-analysis. Costs were estimated in 2022 US dollars. Utilities were based on applying US value set to EQ-5D-5L data collected in trial and literature. RESULTS: Compared to observation, pembrolizumab increased total costs by $80,423 and provided gains of 1.17 quality-adjusted life years (QALYs) and 1.24 life years (LYs) over lifetime, resulting in incremental cost-effectiveness ratios of $68,736/QALY and $65,059/LY. The higher upfront costs of adjuvant treatment were largely offset by reductions in costs of subsequent treatment, downstream disease management, and terminal care, reflecting the lower risk of recurrence with pembrolizumab. Results were robust in one-way sensitivity and scenario analyses. At a $150,000/QALY threshold, pembrolizumab was cost-effective vs. observation in 73.9% of probabilistic simulations that considered parameter uncertainty. CONCLUSION: As an adjuvant treatment of stage IIB or IIC melanoma, pembrolizumab was estimated to reduce recurrence, extend patients' life and QALYs, and be cost-effective versus observation at a US willingness-to-pay threshold.