FDA Grants Jemperli Accelerated Approval for Rectal Cancer, Reports Durable Response in 47%
Key Facts
The U.S. Food and Drug Administration on October 19, 2026, granted accelerated approval to dostarlimab, known as Jemperli, to treat adults with locally advanced stage II or III rectal cancer, according to an agency statement. Use requires that the disease has not been treated previously and that the tumor is MSI-H or dMMR, with these characteristics confirmed by an FDA-approved test. The FDA describes Jemperli as the first and only immunotherapy approved for this specific group, not for all patients with rectal cancer. The drug is used alone under the approved regimen. It may allow some patients to avoid surgery, radiation and chemotherapy, but the approval does not mean every patient will be able to avoid these treatments.
The decision was based on interim results from AZUR-1, an open-label, multicenter, single-arm phase 2 trial that enrolled 154 patients who had not received prior treatment. Participants received up to 9 doses of Jemperli over 6 months, with 3 weeks between doses. In an analysis of 116 evaluable patients assessed by independent central review, the rate of a durable complete clinical response at 12 months was 47%, according to the FDA. This measure counts responses that persist at the specified follow-up threshold, not every complete response recorded during the study. In another analysis, the objective response rate by central review was 79%, while the rate of a durable complete response at 12 months was 68% based on investigator assessments in 144 evaluable patients.
The FDA said 38 additional patients achieved a complete clinical response by central review, but their follow-up was less than 12 months when the data were cut off; they therefore remained under observation and were not included in the calculation of a durable response at 12 months. This group illustrates why response measures differ in the AZUR-1 results: a recorded complete response does not mean that a patient completed the follow-up period needed to establish its durability. According to FDA data, 110 patients, or 71% of all those treated, received the drug alone without additional treatment and without disease progression. By contrast, 26 patients, or 17%, underwent surgery, and 13 patients, or 8%, received additional systemic therapy or radiation. These figures show that a group of participants avoided subsequent treatment, while others needed it or underwent surgery.
Patients with locally advanced rectal cancer typically receive chemotherapy and radiation before surgery, according to the FDA. These treatments may be associated with consequences including impaired bowel, urinary and sexual function, and infertility. Dostarlimab targets the PD-1 protein on immune cells, disabling one of the signals cancer cells use to protect themselves from the immune system, the agency said. The benefit of this approach remains limited to tumors with specific genetic characteristics, which the FDA estimated are present in about 3% of locally advanced rectal cancer cases. The approval therefore focuses on a small group identified through testing, rather than changing standard treatment for everyone with this type of cancer.
On safety, GSK reported serious adverse reactions in 20% of patients in AZUR-1 and permanent discontinuation of treatment due to adverse reactions in 3%. The most common effects included fatigue in 32%, rash in 22%, diarrhea in 18% and itching in 17%, according to the company. The FDA also lists warnings for immune-mediated adverse reactions, infusion-related reactions, complications of allogeneic hematopoietic stem cell transplantation and embryo-fetal toxicity. GSK said a median follow-up of more than 2 years had recorded no recurrence among responders as of the date of its statement. The company quoted the trial's principal investigator as saying that no recorded recurrence during this period could support physicians' confidence in an organ-preservation approach for this group, while follow-up continues.
The approval carries accelerated-approval status, making confirmation of sustained clinical benefit part of the subsequent regulatory process. The FDA required continued patient follow-up to show that responses provide lasting clinical benefit and said longer follow-up is needed to understand response duration and the rate of cancer recurrence. It also listed completion of AZUR-1 among postmarketing requirements to verify and describe clinical benefit. The agency said its review of the application was completed about 4 months ahead of its target date, after granting priority review and breakthrough therapy designation. AZUR-1 results are scheduled to be presented in a late-breaking oral session at the European Society for Medical Oncology congress, according to GSK. Continued participant follow-up and completion of the trial will remain central to establishing how long the benefit underpinning the approval lasts.