GSK announced Monday that its immunotherapy Jemperli, also known as dostarlimab, achieved the primary objective in a mid-stage clinical trial testing the drug in a genetically defined subgroup of locally advanced rectal cancer.
The phase II AZUR-1 study reported a clinically meaningful rate of patients who showed no detectable signs of cancer for one year or more following treatment. The trial focused on tumors unable to repair DNA damage correctly - a molecular feature present in an estimated 5% to 10% of the roughly 730,000 rectal cancer cases diagnosed globally each year.
Patients with this DNA-repair deficient tumor subtype are commonly treated with a combination of chemotherapy, radiation and surgery. Those standard approaches can carry significant, lasting consequences, including the potential need for lifelong colostomy bag use and risks to fertility.
Because the tumors targeted in this study accumulate mutations due to impaired DNA damage repair, they tend to be particularly responsive to immune-based therapies such as dostarlimab. Interim safety and tolerability data from AZUR-1 were consistent with the drug’s known profile from prior studies in other solid tumors, the company said.
Jemperli already holds approvals in the United States and the United Kingdom for selected endometrial cancer subtypes. The drug produced sales of $1.1 billion in 2025 and is expected by GSK to be an important driver toward its longer-term revenue objective of more than A340 billion ($53.52 billion) by 2031.
The U.S. Food and Drug Administration has granted Jemperli both Breakthrough Therapy and Fast Track designations. GSK said it intends to present the AZUR-1 trial data to regulators globally for their review.
Context and next steps
The interim AZUR-1 findings provide initial evidence of durable responses in a molecularly defined rectal cancer population and reinforce the drug e2 80 99s established safety profile in solid tumors. GSK will pursue regulatory engagement using these data.