Quality-adjusted time without symptoms of disease progression or toxicity of treatment in patients with primary advanced or recurrent endometrial cancer treated with dostarlimab plus carboplatin-paclitaxel versus carboplatin-paclitaxel

Objective: In part 1 of the phase 3 RUBY trial (NCT03981796) in patients with primary advanced or recurrent endometrial cancer, dostarlimab plus carboplatin-paclitaxel significantly improved progression-free and overall survival vs placebo plus carboplatin-paclitaxel. Post hoc analyses examined the impact of adding dostarlimab to chemotherapy, compared with placebo plus chemotherapy, on quality-adjusted time without symptoms of disease progression or treatment-related toxicity in this patient population. Methods: Patients were randomized 1:1 to receive dostarlimab/placebo plus chemotherapy every 3 weeks for 6 cycles, followed by dostarlimab/placebo monotherapy every 6 weeks for up to 3 years. Data from the first interim analysis (September 28, 2022) were used, and quality of life (QoL) was assessed with the EuroQoL 5-Dimensions 5-Level questionnaire. Quality-adjusted time without symptoms of disease progression or treatment-related toxicity was calculated as the sum product of the restricted mean survival times spent in 3 mutually exclusive states: toxicity, time without symptoms of disease progression or treatment toxicity, and relapse, and utilized each state's corresponding QoL. Results: In the dostarlimab and placebo arms, 241 and 246 patients were analyzed for safety, respectively. In the overall population, the mean (95% CI) duration of quality-adjusted time without symptoms of disease progression or treatment-related toxicity was significantly longer in the dostarlimab arm (24.75 months [22.88 to 26.65 months]) than in the placebo arm (20.34 months [18.95 to 21.76 months]; the mean difference [95% CI] of 4.41 months [2.01 to 6.77 months], p <.001). Benefits in quality-adjusted time without symptoms of disease progression or treatment-related toxicity after dostarlimab treatment were observed regardless of mismatch repair/microsatellite instability status or toxicity criteria used and were predominantly driven by the time without symptoms of disease. Conclusions: Dostarlimab plus carboplatin-paclitaxel treatment is associated with meaningful improvement in survival, avoidance of substantial toxicity, and maintenance of patient-reported QoL in patients with primary advanced or recurrent endometrial cancer.