FDA Grants Accelerated Approval to Dostarlimab-Gxly for dMMR Endometrial Cancer

The Food and Drug Administration granted accelerated approval to dostarlimab-gxly (Jemperli, GlaxoSmithKline LLC) for adult patients with mismatch repair deficient (dMMR) recurrent or advanced endometrial cancer, as determined by an FDA-approved test, that has progressed on or following a prior platinum-containing regimen.

Efficacy was evaluated based on cohort (A1) in GARNET Trial (NCT02715284), a multicenter, multicohort, open-label trial in patients with advanced solid tumors. The efficacy population consisted of 71 patients with dMMR recurrent or advanced endometrial cancer who progressed on or after a platinum-containing regimen. Patients received dostarlimab-gxly, 500 mg intravenously, every 3 weeks for 4 doses followed by 1,000 mg intravenously every 6 weeks.

The main efficacy endpoints were overall response rate (ORR) and duration of response (DOR), as assessed by blinded independent central review (BICR) according to RECIST 1.1. Confirmed ORR was 42.3% (95% CI: 30.6%, 54.6%). The complete response rate was 12.7% and partial response rate was 29.6%. Median DOR was not reached, with 93.3% of patients having durations ≥6 months (range: 2.6 to 22.4 months, ongoing at last assessment).

Serious adverse reactions occurred in 34% of patients receiving dostarlimab-gxly. Serious adverse reactions in >2% of patients included sepsis , acute kidney injury , urinary tract infection , abdominal pain , and pyrexia . The most common adverse reactions (≥20%) were fatigue/asthenia, nausea, diarrhea, anemia, and constipation. The most common grade 3 or 4 adverse reactions (≥2%) were anemia and transaminases increased. Immune-mediated adverse reactions can occur including pneumonitis, colitis, hepatitis, endocrinopathies, and nephritis.

The recommended dostarlimab-gxly dose and schedule (doses 1 through 4) is 500 mg every 3 weeks. Subsequent dosing, beginning 3 weeks after dose 4, is 1,000 mg every 6 weeks until disease progression or unacceptable toxicity. Dostarlimab-gxly should be administered as an intravenous infusion over 30 minutes.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).

FDA also approved the VENTANA MMR RxDx Panel as a companion diagnostic device for selecting endometrial cancer patients for treatment with dostarlimab-gxly.

This review used the Real-Time Oncology Review (RTOR) pilot program, which streamlined data submission prior to the filing of the entire clinical application, and the Assessment Aid, a voluntary submission from the applicant to facilitate the FDA’s assessment.

This application was granted priority review, and breakthrough therapy designation. A description of FDA expedited programs is in the Guidance for Industry: Expedited Programs for Serious Conditions-Drugs and Biologics.