Adding dostarlimab to treatment with carboplatin and paclitaxel improves progression-free survival (PFS) in patients with advanced or recurrent endometrial cancer, according to research presented at the ASCO Annual Meeting 2023.
Dostarlimab reduced the risk of progression by 34% in the overall study population and by 71% in patients with mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) disease, said study presenter Matthew A. Powell, MD, of the Washington University School of Medicine in St Louis.
These results come from the phase 3 RUBY trial (ClinicalTrials.gov Identifier: NCT03981796), which included 494 patients with primary stage III-IV or first recurrent endometrial cancer. The patients were randomly assigned to receive carboplatin-paclitaxel plus either dostarlimab (n=245) or placebo (n=249) for 6 cycles, followed by dostarlimab or placebo monotherapy every 6 weeks for up to 3 years.
According to blinded independent central review (BICR), in the overall population, the median PFS was 13.0 months in the dostarlimab arm and 8.8 months in the placebo arm (hazard ratio [HR], 0.66; 95% CI, 0.517-0.853; P <.0006). The 24-month PFS rate was 42.5% in the dostarlimab arm and 25.4% in the placebo arm.
In the dMMR/MSI-H population, the median PFS was not reached in the dostarlimab arm and was 9.5 months in the placebo arm (HR, 0.29; 95% CI, 0.158-0.543; P <.0001), according to BICR. The 24-month PFS rate was 66.3% in the dostarlimab arm and 26.0% in the placebo arm.
In the overall population, the objective response rate (ORR) per BICR was 68.2% in the dostarlimab arm and 59.4% in the placebo arm. In the dMMR/MSI-H population, the ORR was 77.1% in the dostarlimab arm and 63.3% in the placebo arm.
Grade 3 or higher treatment-emergent adverse events (TEAEs) occurred in 70.5% of patients in the dostarlimab arm and 59.8% of those in the placebo arm. TEAEs related to dostarlimab led to death in 2 patients. The causes of death were myelosuppression and hypovolemic shock.
“Dostarlimab plus carboplatin-paclitaxel chemotherapy demonstrated a statistically significant and clinically meaningful PFS benefit in the overall population, with a substantial and transformative benefit in patients with dMMR/MSI-H tumors,” Dr Powell said.
Disclosures: This research was supported by GSK. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Powell MA, Hietanen S, Coleman RL, et al. Dostarlimab for primary advanced or recurrent (A/R) endometrial cancer (EC): Outcomes by blinded independent central review (BICR) of the RUBY trial (ENGOT-EN6-NSGO/GOG-3031/RUBY). ASCO 2023. June 2-6, 2023. Abstract 5503.