Dostarlimab is a PD-1 inhibitor monoclonal antibody drug designed for the treatment of various types of cancer. Recent studies have suggested that deficient mismatch mutation repair mechanisms could render endometrial cancers sensitive to anti-programmed death 1 therapies. This study aims to evaluate the antitumor activity and safety of dostarlimab in patients with deficient mismatch repair endometrial cancer.

This open-label, ongoing, multicenter study included a total of 104 women with deficient mismatch mutation repair endometrial cancer. The patients were assigned in a non-randomized way to receive 500 mg dostarlimab intravenously (4 doses, every 3 weeks), followed by 1000 mg (every six weeks) until disease progression, withdrawal, or treatment discontinuation. The primary outcome of the study was objective response rate and duration of response.

During a median follow-up of 11.2 months, a confirmed response was recorded in 30 patients (objective response rate 42.3%), a confirmed complete response in 9 patients (12.7%), and a confirmed partial response in 21 patients (29.6%). Although the responses were durable, the median response duration was not achieved. Anemia (2.9%), colitis (1.9%), and diarrhea (1.9%) were some commonly reported severe adverse events.

The research concluded that treatment with dostarlimab was associated with a higher response rate and antitumor activity in patients with deficient mismatch repair endometrial cancer.