OBJECTIVES: Few treatment options exist for patients with advanced or recurrent endometrial cancer (EC) that has progressed after treatment with platinum-based therapy. Dostarlimab and pembrolizumab are approved for patients with advanced cancers that have not responded to prior therapy and are mismatch repair deficient (dMMR). This analysis aimed to add to the evidence on the cost-effectiveness of immunotherapy for advanced or recurrent dMMR EC.

METHODS: Immunotherapy was compared to usual care (pegylated doxorubicin, PLD). A partitioned survival model was used to estimate probabilities of progression free survival, overall survival and death over a 25-year time horizon. Probabilities of being in each state were derived from survival curves in the published literature. Costs and utilities were derived from published literature and government estimates and discounted at 3 percent annually. Per-cycle costs of PLD, pembrolizumab, and dostarlimab were $1,680, $10,910, and $11,038, respectively. Model outputs were life-years gained, quality-adjusted life-years (QALYs) gained, costs, and incremental cost effectiveness ratios (ICERs). One-way sensitivity analysis was conducted to assess the impact of parameter uncertainties on modeled outcomes.

RESULTS: Compared to PLD, pembrolizumab resulted in 3.18 life-years and 2.20 QALYs gained, with an incremental cost of $612,125 and an ICER of $278,123 per QALY gained. Pembrolizumab was subject to extended dominance by dostarlimab, which yielded a gain of 3.84 life-years and 2.62 QALYs, with an incremental cost of $703,819 ($268,910 per QALY gained). Results were sensitive to cycles of therapy needed to attain maximum clinical benefit and per-cycle cost of progressed disease.

CONCLUSIONS: Dostarlimab and pembrolizumab led to increases in life expectancy and quality of life compared to PLD, but these results suggest they may not currently be priced in line with expected clinical benefit at a willingness-to-pay threshold of $150,000/QALY. More work is needed to understand clinical trajectories following treatment with immunotherapy and cycles needed to attain maximum benefit.