Some patients with locally advanced rectal cancer can now be offered an immunotherapy instead of the usual sequence of chemotherapy, radiation and surgery. On 19 October 2026, the U.S. Food and Drug Administration (FDA) granted accelerated approval to Jemperli (dostarlimab-gxly), made by GSK, for adults with previously untreated stage II or stage III locally advanced rectal cancer whose tumours are microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), as determined by an FDA-authorized test for solid tumours. GSK describes Jemperli as the first and only immunotherapy approved for this population. The FDA estimates that about 3% of locally advanced rectal cancers carry the dMMR or MSI-H characteristic.
What the FDA Approved
The new use is for Jemperli on its own, before any other cancer treatment, in a biomarker-defined group. Patients in the supporting trial received 500 mg of dostarlimab by intravenous infusion every three weeks for nine cycles over about six months. The standard treatment these patients would otherwise face combines chemotherapy, radiation and surgery, and the FDA and GSK both note that those treatments can have lasting effects, including bowel, urinary and sexual dysfunction, secondary cancers and infertility. GSK's chief scientific officer, Tony Wood, summarised the change in the company's announcement: “For decades, treatment has relied on chemotherapy, radiation and surgery.” The application carried FDA Fast Track and Breakthrough Therapy designations and Priority Review, and the approval arrived ahead of the February 2027 decision date after the product received a National Priority Voucher. The FDA counts it as the eleventh approval of a drug reviewed under the Commissioner's National Priority Voucher pilot programme. Full interim trial data are scheduled for presentation at the European Society for Medical Oncology Congress in Madrid on 25 October 2026.
The AZUR-1 Evidence Behind the Decision
The approval rests on AZUR-1, a global, open-label, single-arm phase II trial in 154 patients with previously untreated, histologically confirmed stage II or III MSI-H/dMMR locally advanced rectal cancer. The primary measure was a clinical complete response, meaning no detectable signs of cancer, sustained for 12 months. By independent central review, 47% of evaluable patients (54 of 116; 95% CI: 37%, 56%) met that measure, with a further 38 patients having already achieved a complete response but not yet reached 12 months of follow-up. By investigator assessment, 68% of evaluable patients (98 of 144; 95% CI: 60%, 76%) achieved a sustained 12-month complete response, and an exploratory analysis found 76% (110 of 144) had no evidence of cancer one year or more after treatment. At a median follow-up of 26.3 months, 110 of the 154 patients (71%) had been treated with dostarlimab alone, received no additional treatment and had no disease progression. 26 patients went on to surgery, with or without further therapy, and 13 received additional systemic therapy or radiation. GSK reports that no disease recurrences have been reported among responders to date.
Safety Profile and the Conditions on the Approval
The safety picture matches Jemperli's established profile in solid tumours. Serious adverse reactions occurred in 20% of patients, the most common reactions were fatigue (32%), rash (22%), diarrhoea (18%) and itching (17%), and 3% of patients stopped treatment permanently because of adverse reactions. Two conditions on the approval matter for how clinics should describe it. First, it is an accelerated approval based on sustained clinical complete response at 12 months, not on survival or surgery-free survival, and continued approval may be contingent on verification of clinical benefit in confirmatory trials. Second, GSK states plainly in the product information that the long-term risk of relapse is unknown. Patients who respond enter non-operative management, which in the trial meant structured surveillance with endoscopy, rectal MRI and CT imaging, every four months for the first two years and every six months after that.
What This Means for Cancer Centres
For cancer centres and colorectal practices, the immediate work is identification and pathway design, not promotion. Eligibility turns on MSI-H/dMMR testing at diagnosis, so pathology workflows need to surface the biomarker result early enough for the immunotherapy option to be discussed before standard treatment begins. The Colorectal Cancer Alliance made the same point in GSK's announcement, calling biomarker testing at diagnosis essential. Organisations also need a credible watch-and-wait pathway for responders: scheduled multimodal surveillance, clear ownership of follow-up, and patient communication that explains both the opportunity and the uncertainty honestly. That is a patient-experience and care-coordination task as much as a clinical one, and it connects directly to how practices present treatment options and follow-up through their patient-facing systems. See https://medclinicx.com/solutions/ai-patient-portal and https://medclinicx.com/blog/improve-patient-experience. Finance and access teams should note that an accelerated approval can still face payer scrutiny while confirmatory evidence matures. This article is general information about a regulatory decision, not medical advice for any individual patient.
Analysis: A Real Option, With the Hardest Evidence Still to Come
Analysis (MedClinicX): The striking feature of AZUR-1 is not only the response rate but what non-response management looked like: most patients avoided the treatments that define rectal cancer care today, and those who needed surgery or further therapy still received it. That makes the approval genuinely practice-changing for a small, testable population. The caution is built into the numbers. The independent-review figure (47%) is materially lower than the investigator figure (68%), the trial has no control arm, and the approval endpoint measures response at 12 months rather than whether patients live longer or stay surgery-free over five years. Clinics adopting the pathway early are therefore buying into a surveillance obligation as much as a drug: the value of the option depends on follow-up systems that do not lose responders over years of scans and scopes. Expect the 25 October ESMO presentation and the confirmatory programme to be watched closely by payers and guideline bodies alike.
Sources and References
- U.S. Food and Drug Administration, FDA Approves Immunotherapy That May Allow Certain Patients with Rectal Cancer to Avoid Chemotherapy, Radiation and Surgery, 19 October 2026: https://www.fda.gov/news-events/press-announcements/fda-approves-immunotherapy-may-allow-certain-patients-rectal-cancer-avoid-chemotherapy-radiation-and
- 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: https://us.gsk.com/en-us/media/press-releases/jemperli-dostarlimab-gxly-approved-in-us-as-first-and-only-immunotherapy-for-adults-with-msi-hdmmr-locally-advanced-rectal-cancer/
- Pharmacy Times, Dostarlimab Receives FDA Accelerated Approval for MSI-H/dMMR Locally Advanced Rectal Cancer, 19 October 2026: https://www.pharmacytimes.com/view/dostarlimab-receives-fda-accelerated-approval-for-msi-h-dmmr-locally-advanced-rectal-cancer
- Cancer Network, FDA Approves Dostarlimab in Previously Untreated Locally Advanced Rectal Cancer, 19 October 2026: https://www.cancernetwork.com/view/fda-approves-dostarlimab-in-previously-untreated-locally-advanced-rectal-cancer
- Healio, Jemperli wins FDA nod as first immunotherapy for locally advanced rectal cancer, 19 October 2026: https://www.healio.com/news/hematology-oncology/20261019/jemperli-wins-fda-nod-as-first-immunotherapy-for-locally-advanced-rectal-cancer
Reporting based on the sources above, accessed 20 October 2026. The FDA announcement and the GSK announcement were read directly in full. MedClinicX did not conduct original reporting or interviews for this article. Corrections: contact us via https://medclinicx.com/contact