An ambispective, real-world multi-center study of DOstarlimab in patients with Recurrent or Advanced DNA mismatch repair deficient/microsatellite instability-high endometrial cancer (GEICO 120-R/DORA study)

Patients with advanced or recurrent endometrial cancer who experience progression following platinum-based chemotherapy have limited treatment options. The phase I GARNET trial showed the high efficacy of dostarlimab in treating mismatch repair deficient (dMMR) and/or microsatellite instability-high (MSI-H) endometrial cancer. DORA is a multi-center, ambispective, observational real-world study evaluating the efficacy and safety of dostarlimab. The study included patients with dMMR/MSI-H endometrial cancer who had experienced tumor progression on or after a platinum-based treatment and had received at least 1 cycle of dostarlimab within the Spanish Expanded Access Program. The primary endpoints were objective response rate and duration of response. A total of 129 patients from 57 of the Spanish Research Group for Gynaecological Cancer (GEICO) affiliated hospitals were enrolled, with 125 evaluable for radiological response. The median duration of dostarlimab administration was 8.8 months (interquartile range; 13.2), and 73 patients (57%) remained on therapy at the data cutoff. With a median follow-up of 11.6 months (range; 0.8-30.1), the objective response rate was 53.6% (95% CI 44.4 to 62.5). Complete response was observed in 27 patients (21.6%), and partial response in 40 (32%), with a median time to response of 2.9 months (95% CI 2.6 to 3.6). The median duration of response was not reached. The probability of maintaining the response at 12 and 24 months was 84.98% (95% CI 70.8 to 92.5) and 73.39% (95% CI 50.5 to 86.9), respectively. Treatment was discontinued due to toxicity in 4.7% of patients. Dostarlimab monotherapy in dMMR/MSI-H endometrial cancer patients shows similar efficacy in real-world practice to that observed in the GARNET trial.