Use, survival, and adverse events of dostarlimab monotherapy in advanced or recurrent endometrial cancer: a nationwide cohort study in France

Dostarlimab, a PD-1 inhibitor, was approved in Europe as monotherapy for patients with advanced or recurrent mismatch repair-deficient (dMMR) endometrial cancer, based on the phase I GARNET study. As real-world data remain limited, this study aimed to describe the characteristics and survival outcomes of patients treated in routine clinical practice. Using the French National Health Data System (SNDS), a cohort of all patients who received dostarlimab monotherapy through the French early access program between November 3, 2020 and December 10, 2021 was identified and followed until death, or end of the study period (December 31, 2025). Overall survival (OS), time to treatment discontinuation (TTD), and real-world progression-free survival (rwPFS) were estimated using the Kaplan-Meier method. Severe adverse events were identified based on hospital discharge diagnosis. Among 148 women included, the median age was 71 years (interquartile range: 63-76). Median OS was 17.0 months (95% confidence interval: 13.0-31.0), while median TTD and rwPFS were 4.0 (4.0-6.0) and 9.0 (7.0-12.0) months, respectively. During dostarlimab exposure, 9.5% of patients reported severe digestive adverse events, and 8.1% anemia. Our findings reported less favorable outcomes than in GARNET, and confirm the importance of complementing clinical trial data with real-world data to better assess the effectiveness and safety of innovative treatments across broader, unselected populations.