Cost-Effectiveness of Dostarlimab Monotherapy for the Second-Line Treatment of Advanced or Recurrent dMMR/MSI-H Endometrial Cancer Patients Previously Treated With Platinum-Based Chemotherapy in Spain

OBJECTIVES: Endometrial cancer (EC) is the fourth most common malignancy among women in Spain, with an incidence of 13-14/100,000 annually. It usually appears post-menopause, and most cases are diagnosed early. However, 20% of patients are diagnosed at an advanced stage, where the 5-year survival rate is only 20%. In these cases, first-line treatment is typically carboplatin and paclitaxel, and until dostarlimab, no second-line therapy was indicated for these patients. This study evaluates cost-effectiveness of dostarlimab versus current alternatives (CA) for 2L EC dMMR/MSI-H patients from the Spanish National Health System perspective.

METHODS: A partitioned survival model with three states (progression-free survival, progressed disease, and death) was used, including a cohort of dMMR/MSI-H (mismatch repair deficient/microsatellite instability high) EC patients. Dostarlimab efficacy was modelled using data from the GARNET trial. Survival curves of similar patients were used to model the efficacy of CA (real-world treatments from UK´s National Cancer Registration and Analysis Service database). Spanish costs for screening, treatment, disease management and monitoring, subsequent treatments, and adverse events (€, 2023) were considered. Utilities and adverse events disutilities were extracted from the literature. Costs and quality-adjusted life-years (QALYs) were computed for both arms over the patients' lifetime horizon, and probabilistic sensitivity analysis was conducted.

RESULTS: Patients treated with CA had 0.9 QALYs with a cost of 15,278€, while those treated with dostarlimab had 5.3 QALYs (+4.4 QALYs) with a cost of 176,446 € (+161,168€), resulting in an incremental cost-effectiveness ratio (ICER) of 36,403€/QALY. The probabilistic sensitivity analysis showed a mean ICER of 37,815€/QALY.

CONCLUSIONS: Dostarlimab provides nearly six-times of CA QALYs with acceptable incremental costs, making it cost-effective when considering a threshold of €60,000/QALY (previously used with oncology treatments in Spain). This suggests that dostarlimab is a valuable treatment option for 2L dMMR/MSI-H EC patients in terms of efficacy and economic viability.