Cost-Effectiveness Analysis of Pembrolizumab Monotherapy Treatment for Previously Treated Advanced Microsatellite Instability High (MSI-H) or Mismatch Repair Deficient (dMMR) Solid Tumors in Greece

OBJECTIVES: Patients with MSI-H/dMMR solid tumors have limited therapeutic options at their disposal. Pembrolizumab is indicated for pre-treated MSI-H/ dMMR tumors, including colorectal, endometrial, gastric, small intestine and biliary cancers, based on KEYNOTE-158 and KEYNOTE-164 clinical trials. This study aimed to estimate the cost-effectiveness of pembrolizumab for patients with previously treated MSI-H/dMMR solid tumors in Greece.

METHODS: A partitioned survival model with three health states (progression-free, progressed disease, and death) was developed using the Greek payer perspective over a lifetime horizon. Efficacy and safety data for pembrolizumab were obtained from KEYNOTE-158 and KEYNOTE-164 trials, whereas comparator outcomes were derived from the literature. For each tumor site a weighted average of the available comparators based on market share constituted the standard of care (SoC). Drug acquisition costs and healthcare resource utilization data were extracted from the literature and public sources. An annual discount of 3.5% was applied to both costs and outcomes. Tumor sites were modelled separately and then pooled, weighted by tumor site distribution. Model robustness and uncertainty were assessed through one-way sensitivity (OWSA) and probabilistic sensitivity analyses (PSA).

RESULTS: A pairwise comparison between pembrolizumab and a weighted SoC was conducted. Pembrolizumab was associated with €78,746.77 incremental costs, 7.405 life years gained and 3.488 additional quality-adjusted life years (QALYs), yielding an incremental cost-effectiveness ratio of €22,573/QALY when compared with the weighted SoC, which is significantly lower than the country’s willingness to pay threshold of €52,770. OWSA and PSA confirmed the robustness of the results.

CONCLUSIONS: The analysis suggests that pembrolizumab monotherapy for the treatment of previously treated MSI-H/dMMR solid tumors is cost-effective compared to SoC from a payer perspective in Greece.