GSK Plc (LON:GSK) has announced positive interim results from the registrational phase II AZUR-1 trial of Jemperli (dostarlimab) in patients with stage II/III mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) locally advanced rectal cancer. The single arm trial met its primary objective, showing a meaningful and sustained clinical complete response rate at 12 months (cCR12).
· Primary objective met in interim analysis, with clinically significant rate of participants showing no detectable signs of cancer one year or more after treatment
· Results support potential for dostarlimab to eliminate the need for chemotherapy, radiation and surgery in some patients
· Data to be shared with health authorities for regulatory review, including accelerated review in the US
These results support the potential for dostarlimab, if approved, to become the first immunotherapy capable of eliminating or delaying the need for chemotherapy, radiation and surgery for some patients in this population.
Rectal cancer, a type of bowel cancer, affects around 730,000 people globally each year1 and approximately 5-10% of all rectal cancers have the dMMR/MSI-H subtype2. Current standard of care typically includes chemotherapy, radiation, and surgery3. While often effective, these treatments can profoundly impact a patient’s quality of life, potentially leading to lifelong use of a colostomy bag, significant physiological dysfunction, and infertility4,5,6.
Hesham Abdullah, Senior Vice President, Global Head Oncology, R&D, GSK, said: “The AZUR-1 results support the potential for dostarlimab to transform treatment for dMMR/MSI-H locally advanced rectal cancer. For many patients today, rectal cancer treatment comes with the tolerability burden and lasting impacts from chemotherapy, radiation and surgery. These data demonstrate that some patients may be able to avoid those interventions while remaining free of detectable signs of cancer.”
AZUR-1 results represent a substantial improvement compared to the historical standard of care7 and build on earlier research conducted in collaboration with Memorial Sloan Kettering Cancer Center, which first demonstrated the potential for dostarlimab to achieve clinical complete responses without other treatments in patients with dMMR/MSI-H locally advanced rectal cancer.
In interim data, the safety and tolerability profile of dostarlimab was consistent with its well-characterised and manageable safety profile observed across solid tumours.
Dostarlimab has received both Breakthrough Therapy and Fast Track designations from the US Food and Drug Administration (FDA) in this setting. GSK plans to share interim AZUR-1 data with global regulatory authorities to support review. Detailed results will be presented at a future scientific congress.
References
1. International Agency for Research on Cancer (IARC) (2024) Rectum cancer fact sheet: GLOBOCAN 2022. World Health Organization. Available at: https://gco.iarc.who.int/media/globocan/factsheets/cancers/9-rectum-fact-sheet.pdf. Date accessed: June 2026
2. Cercek A, et al. Mismatch Repair-Deficient Rectal Cancer and Resistance to Neoadjuvant Chemotherapy. Clin Cancer Res. 2020 Jul 1;26(13):3271-3279. doi: 1158/1078-0432.CCR-19-3728. Epub 2020 Mar 6. PMID: 32144135; PMCID: PMC7348681.
3. Fadlallah, H., El Masri, J., Fakhereddine, H. et al. (2024) ‘Colorectal cancer: Recent advances in management and treatment’, World Journal of Clinical Oncology, 15(9), pp. 1136-1156. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC11438855/
4. Cercek, A., Lumish, M., Sinopoli, J. et al. (2022) ‘PD‑1 blockade in mismatch repair-deficient, locally advanced rectal cancer’, New England Journal of Medicine, 386(25), pp. 2363-2376. Available at: https://www.nejm.org/doi/full/10.1056/NEJMoa2201445
5. Negro, S. et al. (2025) ‘Quality of life in rectal cancer treatments: a systematic review’, Cancers, 17(14), 2310. Available at: https://www.mdpi.com/2072-6694/17/14/2310
6. Neibart, S.S. et al. (2020) ‘Quality of life after radiotherapy for rectal cancer’, Current Colorectal Cancer Reports, 16(1), pp. 1-10. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC7336840/
7. Cercek A, Roxburgh CS, Strombom P, et al. Adoption of Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer. JAMA Oncol. 2018;4(6):e180071. doi:10.1001/jamaoncol.2018.0071
