FDA approves GSK's Jemperli for a specific rectal cancer type

GSK plc (NYSE: GSK) announced that the U.S. Food and Drug Administration has approved Jemperli (dostarlimab-gxly) as a monotherapy for adults with stage II and III microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) locally advanced rectal cancer, under the accelerated approval pathway.

GSK claims the drug is the first and only immunotherapy approved for this indication. The MSI-H/dMMR biomarker is found in approximately 5% to 10% of rectal cancers. Approval was based on data from the phase II AZUR-1 trial, which assessed whether the drug could enable patients to forgo chemotherapy, radiation and surgery — the current standard of care.

In the trial, investigator-assessed data showed 68% of evaluable patients (98 of 144) achieved a sustained clinical complete response at 12 months. An exploratory analysis found 76% of evaluable patients (110 of 144) showed no evidence of cancer one year or more after treatment. No disease recurrences were reported among responders after a median follow-up of more than two years.

Data assessed by Independent Central Review, the primary endpoint, continue to mature, with 47% (54 of 116) of evaluable patients having achieved the 12-month response threshold. An additional 38 participants still progressing through follow-up had already achieved a clinical complete response.

Serious adverse reactions occurred in 20% of patients. The most common adverse reactions were fatigue (32%), rash (22%), diarrhea (18%) and pruritus (17%). Jemperli was permanently discontinued due to adverse reactions in 3% of patients.

The application received FDA Fast Track and Breakthrough Therapy designations, as well as Priority Review and a National Priority Voucher. The supplemental Biologics License Application is being reviewed under Project Orbis, with regulatory reviews ongoing in other participating countries.

Full data from the AZUR-1 interim analysis are expected to be presented at the European Society for Medical Oncology Congress in October 2026. According to the press release, continued approval may be contingent on verification of clinical benefit in a confirmatory trial.

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