Aim: To assess the cost-effectiveness of adjuvant pembrolizumab versus observation for patients with resected stage IIB/IIC melanoma from a third-party payers' perspective in Switzerland over a lifetime horizon.
Materials and methods: A Markov state transition model with four health states (recurrence-free [RF], locoregional recurrence, distant metastases [DM], and death) was developed to determine the cost-effectiveness of pembrolizumab versus observation as an adjuvant treatment in patients with stage IIB/IIC melanoma who have undergone complete resection. The model utilized data from the KEYNOTE-716 randomized controlled trial (ClinicalTrials.gov, NCT03553836). The incremental cost-effectiveness ratio (ICER) (Swiss Franc [CHF] per life year or quality-adjusted life years [QALYs] gained) was calculated. A probabilistic sensitivity analysis and deterministic sensitivity analysis were conducted to assess the robustness of the base case results.
Results: Model results demonstrated that pembrolizumab is highly cost-effective as an adjuvant treatment for resected stage IIB/IIC melanoma versus observation in Switzerland. Base case results showed an ICER of CHF 27,424/QALY (EUR 27,342/QALY; exchange rate: 1 CHF = 0.997 EUR) for pembrolizumab versus observation. Results were most sensitive to changes to transition probabilities from the RF state. Most sensitivity and scenario analyses resulted in ICERs below the willingness-to-pay threshold (WTP) of CHF 100,000. At this WTP, pembrolizumab had a 78.9% probability of being cost-effective versus observation.
Limitations: Due to a limited follow-up period in the KEYNOTE-716 trial, data from other clinical trials in the advanced melanoma setting were synthesized in a network meta-analysis and used to inform transition probabilities from DM to death in the cost-effectiveness model, to overcome the absence of these data from the trial.
Conclusion: The model demonstrated that pembrolizumab is highly cost-effective versus observation in patients with resected stage IIB/IIC melanoma in Switzerland. The ICER was below the WTP threshold of CHF 100,000, commonly used for cost-effectiveness models in Switzerland.
Keywords: I; I1; I10; I15; KEYNOTE-716; Pembrolizumab; Switzerland; adjuvant therapy; cost-effectiveness; melanoma.