Dostarlimab Plus Chemotherapy as New Standard of Care for Patients With Primary Advanced or Recurrent Endometrial Cancer

According to updated results from the global, phase 3 RUBY trial, the addition of dostarlimab to carboplatin and paclitaxel improved overall survival (OS) among patients with primary advanced or recurrent endometrial cancer. 

At first interim analysis, results demonstrated that “treatment with dostarlimab demonstrated a trend for improved OS compared with the placebo regimen. However, the stopping boundary for statistical significance was not crossed at that time,” stated Matthew Powell, MD, Washington University, St. Louis, Missouri, and coauthors.

In this double-blind, placebo-controlled trial, 494 patients with primary advanced stage III, IV, or first recurrent endometrial cancer were randomized on a 1-to-1 basis to receive either 500 mg of dostarlimab (n = 245) or placebo (n = 249), plus carboplatin and paclitaxel every 3 weeks for 6 cycles followed by 1000 mg of dostarlimab or placebo every 6 weeks for up to 3 years. The primary end point was OS. A key secondary end point was safety.

At the data cutoff point, 253 OS events occurred in the overall population and OS maturity was 51%. The addition of dostarlimab reduced the risk of death by 31% (hazard ratio [HR] 0.69; 95% confidence interval [CI], 0.54 to 0.89; P = .0020). Median OS was 44.6 months in the dostarlimab arm and 28.2 months in the placebo arm. Median treatment duration was 43 weeks in the dostarlimab arm and 36 weeks in the placebo arm. Grade ≥3 treatment-emergent adverse events occurred in 72.2% and 60.2% of patients, respectively. The most frequent events occurring in > 5% of patients included anemia, neutropenia, neutrophil count decrease, lymphocyte count decrease, white blood cell count decrease, hypertension, and pulmonary embolism. 

Dr Powell et al concluded, in this patient population “where conventional chemotherapy results in short-lived, modest benefit, dostarlimab in combination with carboplatin–paclitaxel demonstrated a statistically significant and clinically meaningful OS benefit…while demonstrating an acceptable safety profile, representing a new standard of care.” 

Source: 

Powell MA, Biorge L, Willmott L, et al. Overall survival in patients with endometrial cancer treated with dostarlimab plus carboplatin–paclitaxel in the randomized ENGOT-EN6/GOG-3031/RUBY trial. Ann Oncol. Published online: June 9, 2024. doi: 10.1016/j.annonc.2024.05.546