You probably know someone who has been through cancer treatment. Chemotherapy, radiation and surgery often leave deep marks on daily life, long after the tumor itself is gone. For some patients, the hope has always been to skip that part entirely.
On October 19, 2026, the FDA granted accelerated approval to the immunotherapy dostarlimab, sold as Jemperli by GSK. It is cleared for adults with stage II or III locally advanced rectal cancer carrying a specific genetic marker.
For eligible patients, the drug alone may replace surgery, chemotherapy and radiation.
How the drug and the marker work together
Eligibility hinges on two overlapping tumor markers that describe how a cancer repairs its own DNA. Doctors call them MSI-H and dMMR.
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These labels mean the cancer cannot fix small DNA errors well. That failure makes the tumor stand out to the immune system, which is why an immunotherapy like dostarlimab can clear it. The drug blocks a signal called PD-1 that cancer cells use to hide from immune attack.
The marker is identified through an FDA-authorized tumor test, usually ordered by an oncologist shortly after diagnosis.
How common this subgroup actually is
According to GSK, roughly 5 to 10 percent of rectal cancers carry the MSI-H or dMMR marker. The American Cancer Society projects about 49,990 new rectal cancer diagnoses in the United States in 2026.
That still leaves thousands of patients a year who could, in theory, qualify. For context, the agency notes that overall colorectal cancer rates have been rising in adults under 65, which is one reason screening now begins at 45.
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What the trial actually showed
The approval rests on AZUR-1, a single-arm phase 2 trial of 154 previously untreated patients. They received nine infusions of dostarlimab every three weeks for about six months. No surgery, no chemotherapy, no radiation.
After a median follow-up of more than two years, roughly three in four patients still had not needed any of those standard treatments. In the main independently reviewed measure, 47 percent of evaluable patients had sustained complete clinical response at 12 months.
A smaller earlier trial at Memorial Sloan Kettering saw an even higher response, with nearly all 32 original patients remaining cancer-free years later.
What the FDA said about the approval
Angelo de Claro, director of the FDA's Oncology Center of Excellence, spoke about the decision. For certain rectal cancers, he said, "this approval represents a groundbreaking option that avoids surgery, radiation, and chemotherapy."
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The accelerated approval pathway means the FDA has cleared the drug while confirmatory data continue to be collected. Further AZUR-1 results are being presented at the 2026 European Society for Medical Oncology Congress.
What patients should ask their oncologist
Dostarlimab is given as a 500 milligram infusion every three weeks for up to nine cycles. That works out to about six months of treatment.
The most common side effects reported in the trial were fatigue, rash, diarrhea and itching, according to GSK. Serious adverse reactions occurred in about one in five patients. Three percent discontinued treatment because of side effects.
Patients newly diagnosed with stage II or III rectal cancer can ask their oncologist whether their tumor has been tested for MSI-H or dMMR status, which is the gatekeeper to this new option.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.