FDA Grants Accelerated Approval to Dostarlimab for MSI-H/dMMR Rectal Cancer

The US Food and Drug Administration granted accelerated approval to dostarlimab (Jemperli, GSK) on October 19, 2026, for adults with previously untreated stage II/III locally advanced rectal cancer that is microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR). Eligibility requires an FDA-authorized test for solid tumors.

Study Findings

The agency evaluated AZUR-1, a multicenter, single-arm, open-label trial involving 154 patients. Participants received dostarlimab 500 mg intravenously every 3 weeks for nine cycles, unless unacceptable toxicity or disease progression occurred.

Among 116 patients evaluable by independent central review, 47% achieved a clinical complete response sustained for 12 months (cCR12; 95% CI, 27%–56%). The objective response rate was 79% (95% CI, 71%–85%).

Another 38 patients achieved clinical complete response with less than 12 months of follow-up, and 44 had near-complete response. At a median follow-up of 26.3 months, none of the patients in these response groups or the cCR12 group experienced progression.

Overall, 110 patients (71%) received dostarlimab alone without additional treatment or disease progression. Twenty-six patients (17%) underwent surgery, with or without additional therapy.

The FDA also reviewed a separate, 50-patient investigator-led trial. Its cCR12 rate was 93% (95% CI, 82%–99%), and no patients received chemoradiation or rectal cancer surgery as part of treatment.

Clinical Implications

The approval provides a treatment option for biomarker-defined, locally advanced rectal cancer. In AZUR-1, patients achieving clinical complete response entered nonoperative management with multimodal surveillance every 4 months for 2 years and every 6 months thereafter.

Patients without complete response, or with recurrence or progression, were evaluated for standard care at investigator discretion. Among 27 patients followed for at least 3 years in the separate trial, one developed local recurrence treated with lymphadenectomy.

Prescribing information includes warnings for immune-mediated adverse reactions, infusion-related reactions, complications of allogeneic hematopoietic stem cell transplantation, and embryo-fetal toxicity.