Jemperli Rectal Cancer Approval: FDA Clears Immunotherapy That May Spare Patients Surgery

The US Food and Drug Administration (FDA) has granted accelerated approval to Jemperli (dostarlimab-gxly) for some patients with locally advanced rectal cancer, a decision the regulator says may allow certain patients to avoid chemotherapy, radiation and surgery altogether. The approval, announced on 19 October 2026 and granted to the British drugmaker GSK, makes Jemperli the first immunotherapy approved in the US for this group of patients, according to the company.

The Jemperli approval applies only to adults with previously untreated stage II or stage III rectal cancer whose tumours are mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H), as confirmed by an FDA-authorised test. That is a minority of patients, but for them the decision could change what treatment looks like.

What Has the FDA Approved?

Jemperli is a PD-1 blocking antibody, a type of immunotherapy that releases a “brake” cancer cells use to hide from the immune system. Under the new approval, it is used on its own rather than alongside the standard combination of chemotherapy, radiotherapy and surgery.

“Standard treatment for rectal cancer has major life-changing effects. For certain types of rectal cancer, this approval represents a groundbreaking option that avoids surgery, radiation and chemotherapy,” said Dr Angelo de Claro, director of the FDA’s Oncology Center of Excellence. The FDA said those standard treatments can affect bowel, urinary and sexual function, as well as fertility, and that surgery can sometimes lead to a permanent colostomy.

• Medicine: Jemperli (dostarlimab-gxly), made by GSK.
• Who is eligible: adults with previously untreated stage II or III locally advanced rectal cancer that is dMMR or MSI-H.
• Treatment: up to nine doses, given every three weeks over six months, in the main trial.
• Type of approval: accelerated approval, based on interim results.
• Announced: 19 October 2026, nearly four months ahead of schedule, according to the FDA.

How Many Patients Could Benefit?

The eligible group is small. The FDA cited published estimates that about 3% of locally advanced rectal cancers are dMMR or MSI-H, while GSK put the figure at around 5–10% of rectal cancers. The difference partly reflects the populations being described, but both figures make clear that most rectal cancer patients will not qualify.

Testing at diagnosis is therefore crucial. “Biomarker testing at diagnosis will be essential to identifying patients who may be eligible for this treatment,” said Michael Sapienza, chief executive of the Colorectal Cancer Alliance, in GSK’s announcement.

What Did the AZUR-1 Trial Show?

The FDA based its decision on interim results from AZUR-1, a phase 2 trial of Jemperli alone in 154 patients. After a median follow-up of more than two years, almost three-quarters of patients had not needed surgery, radiotherapy or chemotherapy, the regulator said.

GSK reported that, on investigators’ assessment, 68% of evaluable patients (98 of 144) achieved a sustained clinical complete response at 12 months, meaning no detectable cancer a year on. On the trial’s primary measure, assessed by independent central review, the figure so far is 47% (54 of 116), with data still maturing. GSK said no recurrences had been reported among responders to date. Full interim data are due to be presented at the European Society for Medical Oncology (ESMO) Congress in October 2026.

The approval also draws on an earlier study at Memorial Sloan Kettering Cancer Center in New York of 50 patients with the same type of tumour. According to the FDA, none of the patients had detectable signs of cancer after treatment, and 93% stayed cancer-free for at least 12 months; of 27 patients followed for at least three years, one saw the cancer return.

What Are the Risks and Unanswered Questions?

Jemperli can cause the immune system to attack healthy organs and tissues, and these reactions can be severe or fatal, the FDA warned. In the rectal cancer trial, the most common side effects were fatigue, rash, diarrhoea and itching. GSK said serious adverse reactions occurred in 20% of patients, and 3% stopped treatment because of side effects.

Because this is an accelerated approval based on interim results, it is conditional. GSK must keep following patients to show that responses last, and the FDA said longer follow-up is needed to understand how long responses last and how often the cancer returns.

Did GSK Win Another Approval This Week?

Yes. On 20 October, the FDA also approved GSK’s Hibsago (bepirovirsen), used alongside existing antiviral medicine, for certain adults with chronic hepatitis B who do not have cirrhosis. It is the first FDA-approved antisense oligonucleotide for the disease. Across two trials, 24% of patients who received Hibsago met the requirements to stop their existing medicine, compared with none on placebo, and 19% still had the virus under control 24 weeks after stopping all treatment, the FDA said. The drug carries a boxed warning for serious liver reactions and low platelet counts.

What Happens Next for Patients Outside the US?

The Jemperli application is being reviewed under Project Orbis, an FDA programme that allows concurrent review by other regulators, and GSK said reviews were ongoing in participating countries. Patients elsewhere should speak to their oncology team about whether biomarker testing and this approach are relevant to them; the US approval does not by itself make the treatment available in other countries.

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Featured image: Memorial Sloan Kettering Cancer Center sign, New York, by ajay_suresh / Wikimedia Commons, CC BY 2.0.

Sources

• US Food and Drug Administration — FDA Approves Immunotherapy That May Allow Certain Patients with Rectal Cancer to Avoid Chemotherapy, Radiation and Surgery (19 October 2026).
• GSK — Jemperli (dostarlimab-gxly) approved in US as first and only immunotherapy for adults with MSI-H/dMMR locally advanced rectal cancer (19 October 2026).
• US Food and Drug Administration — FDA grants accelerated approval to dostarlimab for locally advanced rectal cancer (October 2026).
• US Food and Drug Administration — FDA Approves First-of-Its-Kind Chronic Hepatitis B Treatment (20 October 2026).