Pembrolizumab in dMMR/MSI-H unresectable or metastatic endometrial cancer: substantial gain in life-years at acceptable cost in the US

Abstract

Pembrolizumab is a highly cost-effective treatment option in the US for previously treated unresectable or metastatic endometrial cancer in women whose tumours have deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H). This is the main finding of a study that used a partitioned survival model to assess the cost effectiveness of pembrolizumab versus chemotherapy (paclitaxel or doxorubicin) in the treatment of women with previously treated dMMR/MSI-H unresectable or metastatic endometrial cancer.* Survival data for the model were obtained from a phase II, open-label, single-arm trial (KEYNOTE-158) for pembrolizumab and from a phase III randomised trial for paclitaxel and doxorubicin. The analysis was conducted from the perspective of a US healthcare payer. The model projected that pembrolizumab was associated a considerable gain in life-years (4.68) and qualityadjusted life-years (QALYs; 3.80) versus chemotherapy over a 30-year time horizon. These gains were due to improved overall and progression-free survival for pembrolizumab. The majority of gains were accrued in the progression-free health state of the model (3.33 of 3.80 incremental QALYs). Treatment with pembrolizumab was associated with an incremental cost of $US220 934 versus chemotherapy over the 30-year time horizon, with the majority of cost accrued for drug acquisition ($US119 426; year 2019 values). The incremental cost was $US47 236 per life-year gained and $US58 165 per QALY gained for pembrolizumab versus chemotherapy. Results were robust to changes in model parameters and assumptions. The probability of pembrolizumab being considered cost effective versus chemotherapy at a willingness-to-pay threshold of $US100 000 per QALY gained was 90.1%.