The Rationale for Dostarlimab Monotherapy In MSI-H and MSS Endometrial Cancer

July 17, 2019
Ana Oaknin, MD

Ana Oaknin, MD, head of the Gynecologic Tumors Unit, Vall d’Hebron University Hospital, and principal investigator, Gynecological Malignancies Group, explains the rationale for analyzing anti–PD-1 monotherapy with dostarlimab in patients with microsatellite instability–high and microsatellite stable endometrial cancer. 

Ana Oaknin, MD, head of the Gynecologic Tumors Unit, Vall d’Hebron University Hospital, and principal investigator, Gynecological Malignancies Group, explains the rationale for analyzing anti—PD-1 monotherapy with dostarlimab(TSR-042) in patients with microsatellite instability–high (MSI-H) and microsatellite stable (MSS) endometrial cancer.

With limited options available for treating women with advanced or recurrent endometrial cancer, the phase I/II GARNET studyanalyzed 125 patients—33% with MSI-H endometrial cancer, 63% with MSS disease, and the remaining with unknown MSI status—receiving treatment with dostarlimab 500 mg in 4 doses every 3 weeks. Patients then received 1000 mg of the anti—PD-1 monotherapy every 6 weeks until disease progression. The study found clinically relevant overall response rates (ORRs). The full population showed a 30% ORR, MSI-H patients had a 49% ORR, and MSS patients had a 20% ORR.

The purpose for this study was to look at anti—PD-1 monotherapy across multiple patient populations for endometrial cancer, says Oaknin. It addresses the limitations with standard therapies and the need for a therapy that targets MSS, unlike the commonly used treatment, pembrolizumab (Keytruda), which was approved specifically for the treatment of patients with MSI-H endometrial cancer.