Most people never give rectal cancer treatment much thought until it is sitting across the kitchen table. And when it does come up, the first word is usually surgery. Then chemotherapy. Then radiation.
On October 19, 2026, the U.S. Food and Drug Administration granted accelerated approval to dostarlimab, sold by GSK under the brand name Jemperli.
It is the first immunotherapy cleared for adults with a specific form of locally advanced rectal cancer.
According to the FDA, eligible patients can be treated with the drug alone, with no surgery, chemotherapy or radiation.
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The approval covers stage II and stage III rectal cancers whose tumor cells carry a biological signature called MSI-H or dMMR. Only about 5 to 10 percent of rectal cancers fall into that group, so the news is targeted, not universal.
What the AZUR-1 trial actually found
Approval rests on a study called AZUR-1, which enrolled 154 adults with that specific tumor type. Everyone received dostarlimab every three weeks for about six months, with no chemotherapy, radiation or surgery.
After a median follow-up of just over two years, 110 of the 154 patients, 71 percent, were still well on dostarlimab alone. None of them had needed surgery, chemotherapy or radiation.
The ASCO Post reports that no patient who reached a complete response in the trial had the cancer come back during that window.
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Why skipping the operation matters
The standard treatment for locally advanced rectal cancer is chemotherapy and radiation followed by surgery that removes part of the bowel.
According to GSK, that package can bring bowel, urinary and sexual problems, secondary cancers or infertility, and many patients are left with a permanent ostomy bag. For patients whose tumors carry the MSI-H or dMMR signature, the new approval opens a route around all of that.
The treatment is not without its own cost. In the trial, the most common side effects were fatigue (32%), rash (22%), diarrhea (18%) and itching (17%).
Dostarlimab, like other PD-1 inhibitors (drugs that free the immune system to attack cancer cells), can also cause the immune system to attack the body's own organs. Serious adverse reactions occurred in 20% of patients, and about 3% had to stop treatment because of side effects.
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Dostarlimab's approval is "accelerated," meaning the FDA has signed off on the drug while longer confirmatory trials continue. Patients can only be considered eligible after an FDA-authorized tumor test shows the MSI-H or dMMR marker.
Anyone with newly diagnosed rectal cancer who wants to know if they qualify should ask their oncologist whether their biopsy has been tested for mismatch-repair status.
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This article is made and published by Mie Hermansen, who may have used AI in the preparation.