GSK is preparing to seek FDA accelerated approval for its cancer drug Jemperli after a phase 2 trial delivered a significant clinical win in a high-profile cancer indication.
Interim results from the phase 2 AZUR-1 study showed a “meaningful and sustained” clinical complete response rate for Jemperli at 12 months in stage 2/3 mismatch repair deficient/microsatellite instability-high locally advanced rectal cancer.
Without disclosing specific figures, GSK said its PD-1 inhibitor demonstrated a “substantial improvement” compared to historical results with existing treatment approaches for the condition.
The company now plans to share the data with global health authorities, including submitting to the FDA under an accelerated approval pathway following the positive interim readout.
Current standard of care for locally advanced rectal cancer involves chemotherapy, radiation, and surgery, which “can profoundly impact a patient’s quality of life, potentially leading to lifelong use of a colostomy.”
Interest in Jemperli’s potential in this area gained widespread public attention in 2022 when researchers at Memorial Sloan Kettering Cancer Center reported complete remissions in all rectal cancer patients in a small trial.
A 2024 update of that single-centre study showed a complete response rate of 100% among 42 patients, with median follow-up exceeding two years for the first 24 patients evaluated.
GSK’s AZUR-1 trial enrolled 154 participants who received nine cycles of Jemperli over six months, with interim results presented at the 2025 annual meeting of the American Association for Cancer Research.
Among the 48 patients who completed six months of treatment, all achieved a clinical complete response and did not require surgery to remove the primary tumour.
The company confirmed that no signs of cancer were observed one year from the end of treatment, as assessed by medical imaging, endoscopy, and a digital rectal exam.
GSK said Jemperli’s safety and tolerability profile in the preliminary results was consistent with findings from prior studies, with detailed data to be presented at a future scientific meeting.
An FDA oncologic advisory committee previously voted 8 to 5 in support of pursuing accelerated approval using complete response data from a single-arm trial, following an unusual advisory meeting in 2023.
The FDA’s advisers at that meeting indicated a preference for longer-term follow-up data beyond 12 months, with two-year and three-year complete response rates among key secondary endpoints.
Alongside AZUR-1, GSK is conducting the randomised phase 3 AZUR-2 trial in mismatch repair deficient resectable colon cancer, with the company arguing that colon and rectal cancers share meaningful biological similarities.
An estimated 5% to 10% of rectal cancers carry the mismatch repair deficiencies that make them susceptible to immunotherapy drugs such as Jemperli.
Both Jemperli and Merck’s Keytruda hold tumour-agnostic FDA indications covering mismatch repair deficient metastatic solid tumours, including colorectal cancer.
Hesham Abdullah, GSK’s global head of oncology R&D, said: “For many patients today, rectal cancer treatment comes with the tolerability burden and lasting impacts from chemotherapy, radiation and surgery.”
Abdullah added: “These data demonstrate that some patients may be able to avoid those interventions while remaining free of detectable signs of cancer.”