Jemperli achieves 76% complete response rate in Phase II rectal cancer trial

GSK has reported positive interim Phase II results showing that Jemperli, also known as dostarlimab, achieved a high complete response rate when used as a standalone treatment in patients with MSI-H or dMMR locally advanced rectal cancer.

The findings come from the AZUR-1 study and are being presented in a late-breaking oral session at the 2026 European Society for Medical Oncology Congress.

The trial is evaluating Jemperli monotherapy in adults with stage II or III microsatellite instability-high or mismatch repair deficient locally advanced rectal cancer.

In an exploratory analysis, 76% of evaluable patients achieved a complete response to Jemperli alone.

This represented 110 of 144 patients.

Among the overall evaluable population, 68%, or 98 of 144 patients, achieved a sustained clinical complete response lasting at least 12 months without undergoing surgery.

An additional 12 patients had a pathological complete response confirmed through tissue analysis after surgery, with no evidence of remaining cancer.

GSK said no disease recurrences had been reported among responders after a median follow-up of more than two years.

The AZUR-1 study met its primary objective by showing that a clinically meaningful proportion of patients achieved a sustained clinical complete response at 12 months.

At the time of the analysis, the independent central review assessment of this endpoint was still maturing.

Among 116 evaluable patients, 47% had achieved a sustained clinical complete response at 12 months.

A further 38 participants had already achieved a clinical complete response but had not yet reached the 12-month assessment point and remained under follow-up.

Jemperli is a PD-1 inhibitor designed to activate an anti-tumour immune response by blocking the interaction between PD-1 and its ligands.

The findings are particularly relevant because standard treatment for locally advanced rectal cancer commonly includes chemotherapy, radiotherapy and surgery.

These approaches can be associated with long-term complications affecting bowel, urinary and sexual function, as well as fertility.

Hesham Abdullah, Senior Vice President and Global Head of Oncology Research and Development at GSK, said the AZUR-1 findings support the potential for Jemperli to offer some eligible patients an alternative to chemotherapy, radiation and surgery.

Andrea Cercek, MD, Principal Investigator of AZUR-1 at Memorial Sloan Kettering Cancer Center, said the absence of reported disease recurrence after more than two years of follow-up supports further confidence in a non-operative treatment strategy for selected patients.

The safety profile of Jemperli was generally consistent with its established profile across solid tumours.

Serious adverse reactions occurred in 20% of patients.

The most commonly reported adverse reactions were fatigue in 32% of patients, rash in 22%, diarrhoea in 18% and pruritus in 17%.

Jemperli was permanently discontinued because of adverse reactions in 3% of patients.

The AZUR-1 data supported the recent U.S. approval of Jemperli in this indication.

Regulatory reviews are also continuing in participating countries through Project Orbis, an initiative led by the FDA Oncology Center of Excellence to support parallel international review of oncology medicines.

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Related Topics and Keywords

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