GSK plc filed a Form 6-K on October 26, 2026, disclosing interim results from the phase II AZUR-1 trial showing that 76% of evaluable patients with MSI-H/dMMR locally advanced rectal cancer achieved a complete response to Jemperli (dostarlimab) monotherapy.

Key Highlights

  • 76% complete response rate: In an exploratory analysis, 110 of 144 evaluable patients (95% CI: 69%, 83%) achieved a complete response to dostarlimab alone, according to the filing.
  • Sustained clinical complete response: 68% of evaluable patients (98/144; 95% CI: 60%, 76%) achieved a sustained clinical complete response for at least 12 months (cCR12) without surgery, as assessed by investigators.
  • No disease recurrences: No disease recurrences have been reported among responders after a median follow-up of more than two years, the filing stated.
  • Primary endpoint data maturing: At the time of analysis, 47% of evaluable patients (54/116; 95% CI: 37%, 56%) had achieved cCR12 per independent central review, with 38 additional participants still under observation.
  • Safety profile: Serious adverse reactions occurred in 20% of patients receiving Jemperli; the most common adverse reactions were fatigue (32%), rash (22%), diarrhoea (18%), and pruritus (17%).
  • US approval supported: The filing noted that the data supported the recent US approval of Jemperli in this indication.
  • Project Orbis reviews ongoing: Regulatory reviews are continuing in participating countries through Project Orbis, an FDA Oncology Center of Excellence initiative, according to the filing.

AZUR-1 Interim Results: Dostarlimab Monotherapy in MSI-H/dMMR Rectal Cancer

GSK plc (LSE/NYSE:GSK) disclosed interim results from the AZUR-1 trial in a Form 6-K issued on October 24, 2026, from London. AZUR-1 is described in the filing as a global, open-label, single-arm, registrational phase II trial evaluating dostarlimab monotherapy in patients (n=154) with previously untreated stage II and III MSI-H/dMMR locally advanced rectal cancer. Patients received nine cycles of dostarlimab over six months, administered as a 500mg intravenous infusion every three weeks.

According to the filing, the trial met its primary objective by demonstrating that a clinically significant proportion of patients achieved cCR12. The exploratory analysis showed 76% of evaluable patients (110/144) achieved a complete response, comprising 68% (98/144) with a sustained clinical complete response for at least 12 months without surgery and 12 additional patients who achieved a pathological complete response confirmed through tissue analysis. The filing reported no disease recurrences among responders after a median follow-up of more than two years. Data on the primary endpoint as assessed by independent central review continue to mature, the filing noted.

The filing cited the safety profile of dostarlimab as "generally consistent with its established profile across solid tumours." Jemperli was permanently discontinued due to adverse reactions in 3% of patients. The findings are to be presented in a late-breaking oral session at the European Society for Medical Oncology (ESMO) Congress. The filing noted that Jemperli was discovered by AnaptysBio, Inc. and licensed to TESARO, Inc. under a collaboration and exclusive license agreement signed in March 2014, with GSK responsible for ongoing research, development, commercialisation, and manufacturing.

What Was Disclosed

GSK plc filed a Form 6-K reporting interim phase II AZUR-1 trial data for Jemperli (dostarlimab) in MSI-H/dMMR locally advanced rectal cancer, including response rates, follow-up data, safety findings, and ongoing international regulatory review status through Project Orbis.