FDA Grants Accelerated Approval for Immunotherapy in Certain Rectal Cancer Patients

The U.S. Food and Drug Administration announced on Tuesday that it has granted accelerated approval for a new indication of the immunotherapy drug Jemperli (dostarlimab-gxly), offering a treatment alternative for select adult patients with locally advanced rectal cancer.

The approval applies to Jemperli used as a single agent in adults with previously untreated stage II or stage III locally advanced rectal cancer whose tumors are mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H), as verified by an FDA-authorized test. According to published estimates cited by the FDA, roughly 3% of locally advanced rectal cancers have these specific genetic characteristics, which make tumors more recognizable to the immune system. Jemperli functions by targeting the PD-1 protein on immune cells, inhibiting signals that cancer cells use to evade immune detection.

Standard care for locally advanced rectal cancer frequently involves chemotherapy and radiation before surgery, treatments that can cause long-term impacts on bowel, urinary, sexual function, and fertility, alongside surgical risks such as leaks, infection, or permanent colostomy.

The regulatory decision was supported by interim data from the ongoing phase 2 AZUR-1 study involving 154 patients. In the trial, participants received up to nine doses of Jemperli over a six-month span. With a median follow-up exceeding two years, nearly three-quarters of the trial participants avoided surgery, radiation therapy, and chemotherapy. Findings from an earlier 50-patient study at Memorial Sloan Kettering Cancer Center also showed high response rates, with no detectable signs of cancer following treatment and 93% maintaining that status for at least 12 months.

Because the approval was granted under the FDA's accelerated pathway, the drug's manufacturer, GSK, is required to conduct further studies and continue monitoring patients to confirm that the therapy provides lasting clinical benefits and to evaluate cancer recurrence rates.

The FDA noted that Jemperli carries risks of immune-mediated adverse reactions, where the immune system attacks healthy tissue, which can be severe or fatal. The most common side effects observed in at least 15% of patients included fatigue, rash, diarrhea, and itching.

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