Ozekibart: New bowel cancer drug halts tumour growth in nine out of 10 patients in Royal Marsden trial

A targeted treatment designed to trigger the death of cancer cells has shown significant promise for patients with advanced bowel cancer when combined with chemotherapy, an early trial has revealed.

Researchers reported that the combination therapy led to tumour shrinkage in some patients and successfully halted the disease’s progression in others.

One patient described the therapy as giving her a “new lease of life”.

The drug, ozekibart, works by mimicking a natural protein, binding to specific receptors on cancer cells to trigger their “death”, while largely sparing healthy tissue.

The Phase I trial, led by the Royal Marsden NHS Foundation Trust, involved 45 patients with advanced bowel cancer whose condition had worsened after two or three prior treatments and who were not eligible for surgery.

They received ozekibart alongside Folfiri chemotherapy, a standard approach.

Results showed that tumours shrank in 20 per cent of patients.

Crucially, the cancer ceased growing in almost nine out of 10 (87 per cent) participants.

In one particularly encouraging case, a follow-up scan revealed no visible tumour.

Dr Hazel Lote, consultant medical oncologist at the Royal Marsden NHS Foundation Trust and honorary appointee at the Institute of Cancer Research, London, said: “These early results are promising for patients with advanced colorectal cancer who have very few treatment options left.

“The combination of ozekibart plus Folfiri not only shrank tumours in some patients, but stopped the cancer from worsening in many others, suggesting this treatment combination could offer a promising new treatment option.”

East Sussex woman Amanda Burgess joined the trial in July 2025.

The 59-year-old was diagnosed with bowel cancer in April 2024 and had surgery to remove the tumour, but was later told the cancer had spread.

“Chemotherapy and immunotherapy followed, but unfortunately they weren’t successful,” Ms Burgess said.

“This new treatment has given me a new lease of life.

“Since starting the trial, I’ve had two significant reductions in the size of my tumour and things are now stable.

“The chemotherapy has been hard at times, but I’ve had no side effects from the trial drug itself.

“My energy has returned, and I’m back to doing the things I love.

“I walk my black labs Cromwell and Pip every day, I’m playing tennis, attending Pilates classes and spending time with my husband, David, and our children.

“I feel incredibly fortunate to be on the trial.”

Dr Lote said the findings, which are being presented at the American Society of Clinical Oncology annual meeting in Chicago, “are really encouraging” and support further research.

Bowel cancer is the fourth most common cancer in the UK, with more than 48,000 new cases diagnosed each year.

It is the second biggest cause of cancer deaths, claiming around 17,700 lives annually.

The trial is being supported by the Bowelbabe Fund for Cancer Research UK, which was set up by Dame Deborah James, who died in June 2022 at the age of 40.