GSK announced positive interim results from the registrational phase II AZUR-1 trial of Jemperli (dostarlimab) in patients with stage 1/3 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 (CRR) at 12 months.

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 year and approximately 5-10 percent of all rectal cancers have the dMMR/MSI-H subtype. Current Standard of Care (SoC) typically includes chemotherapy, radiation, and surgery. 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 infertility.

Hesham Abdullah, Senior Vice President (SVP), 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 SoC 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 tumors.

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.