GSK cancer drug clears rectal tumours in 76% of patients in trial, data shows

GSK Plc (LON:GSK) said on Monday its immunotherapy Jemperli cleared tumours completely in 76% of patients with a certain type of locally advanced rectal cancer, data that could let some patients skip chemotherapy, radiation and surgery.

The result comes from an exploratory analysis of AZUR-1, a phase II trial of Jemperli given on its own to adults with stage II and III rectal cancer with a genetic trait, MSI-H/dMMR, that stops tumours repairing DNA damage properly. In the analysis, 110 of 144 evaluable patients had a complete response.

That included 68% with a complete clinical response lasting at least 12 months without surgery, as assessed by investigators.

Another 12 had a complete response confirmed after surgery showed no cancer in tissue analysis. No recurrences have been reported among responders after median follow-up of more than two years.

AZUR-1 met its main goal of showing a clinically significant share of patients had a complete response lasting 12 months.

Judged by an independent central review, 47% of evaluable patients had reached that point at the time of analysis, with data still maturing. Another 38 had a complete response but had not yet reached 12 months.

Serious adverse reactions occurred in 20% of patients and 3% stopped treatment because of side effects.

Hesham Abdullah, GSK’s global head of oncology R&D, said: “For some patients, avoiding chemotherapy, radiation and surgery may now be possible.” The data supported the recent US approval of Jemperli for this use.

GSK separately reported results from BEHOLD-1, a phase I trial of its experimental antibody-drug conjugate mocertatug rezetecan (Mo-Rez), in platinum-resistant ovarian cancer.

At the dose chosen for phase III, Mo-Rez had a confirmed response rate of 62%, lasting a median 12.2 months; median progression-free survival, the time before disease worsened, was 11.1 months.

Grade 3 or higher treatment-related side effects, mostly blood-related, occurred in 71% of patients; 2% stopped treatment and 2% developed lung inflammation.

GSK, which acquired rights to Mo-Rez from Hansoh Pharma, has five pivotal phase III trials underway. Both datasets will be presented at the European Society for Medical Oncology congress in Madrid.