GSK’s Jemperli wins FDA approval as first immunotherapy for MSI-H/dMMR locally advanced rectal cancer

The US Food and Drug Administration has granted accelerated approval to GSK’s Jemperli (dostarlimab) for adults with stage II and III microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR) locally advanced rectal cancer. It is the first and only immunotherapy approved for this group. The agency approved it ahead of its target action date, after granting Priority Review and a National Priority Voucher. Jemperli had also received Fast Track and Breakthrough Therapy designations for this use.

Standard treatment for locally advanced rectal cancer is chemotherapy, radiation and surgery. These can leave lasting effects, including bowel, urinary and sexual dysfunction, secondary cancers and infertility. MSI-H/dMMR tumours, a biomarker found in around 5 to 10 per cent of rectal cancers, may be treatable with Jemperli alone, which could let eligible patients avoid those interventions.

Tony Wood, chief scientific officer at GSK, said Jemperli is now the first approved immunotherapy for US adults with this type of rectal cancer. He said treatment has relied on chemotherapy, radiation and surgery for decades, and that the approval offers a new approach and a step towards more personalised care.

Dr Andrea Cercek, principal investigator of AZUR-1, section head of colorectal cancer and co-director of the Center for Young Onset Colorectal and Gastrointestinal Cancer at Memorial Sloan Kettering Cancer Center, said the AZUR-1 results show the potential for a fundamentally different approach in a biomarker defined group. She said patients can now access a licensed treatment tailored to the biology of their disease.

Michael Sapienza, chief executive officer of the Colorectal Cancer Alliance, said people with rectal cancer worry about life after treatment as well as the disease itself. He said the possibility of avoiding chemotherapy, radiation and surgery is a meaningful advance for patients and families, and that biomarker testing at diagnosis will be essential to identify those who may be eligible.

The approval rests on the Phase II AZUR-1 trial, which met its primary objective by showing a clinically significant proportion of participants achieved a sustained clinical complete response at 12 months (cCR12). The data are still maturing. In investigator assessed data, 68 per cent of evaluable patients (98 of 144; 95% CI 60 to 76 per cent) reached cCR12. In an exploratory analysis, 76 per cent (110 of 144; 95% CI 69 to 83 per cent) had no evidence of cancer a year or more after treatment. That figure includes the 98 patients who reached cCR12 without surgery, plus 12 others whose complete response was confirmed by tissue analysis after surgery (pathological complete response). No recurrences have been reported among responders after a median follow up of more than two years.

On the primary objective as assessed by independent central review, 47 per cent of evaluable patients (54 of 116; 95% CI 37 to 56 per cent) have achieved cCR12 so far. A further 38 participants still working through the 12 month follow up have already achieved a clinical complete response.

Jemperli’s safety profile was generally consistent with its established profile across solid tumours. Serious adverse reactions occurred in 20 per cent of patients, and the most common adverse reactions were fatigue (32 per cent), rash (22 per cent), diarrhoea (18 per cent) and pruritus (17 per cent). Jemperli was permanently discontinued because of adverse reactions in 3 per cent of patients.

Full data from the AZUR-1 interim analysis will be presented at the European Society for Medical Oncology Congress in October 2026.

The supplemental Biologics License Application is being reviewed under Project Orbis, an FDA Oncology Center of Excellence initiative that allows international health authorities to review applications at the same time. Reviews are ongoing in participating countries.

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