A “killer” cancer treatment could stop one in three tumours growing, according to trials in those with some of the deadliest conditions.

The immunotherapy drug, called AFM24, was shown to work in patients with advanced disease that had stopped responding to treatment, including bowel, lung and pancreatic cancers.

Scientists said they were “excited” by the promise shown by the “highly innovative” treatment, which redirects the body’s own killer immune cells to kill tumours.

They hope it could in future be deployed to work against a range of cancer tumours that continue to grow despite treatment.

The phase one trial by the Institute of Cancer Research (ICR), London, and the Royal Marsden NHS Foundation Trust involved 24 patients with tumours which were positive for EGFR – a key protein involved in cancer growth.

Typically, people were enrolled in the trial as a “last resort” because other treatments had failed.

The drug was able to act as a “warhead” targeted on the protein, without having to go through the complex process of re-engineering a patient’s own cells, researchers said.

Eight of the 24 patients in the trial responded to the immunotherapy and saw their cancers stop growing. Two patients with bowel cancer and one with lung cancer who received the immunotherapy in the ongoing trial saw their cancer shrink or stop growing for more than three months.

‘Results look promising’

Scientists said the findings, presented on Monday at the American Association for Cancer Research conference in New Orleans, show the treatment has the potential to be safer and less complex than existing cell therapies.

Professor Kristian Helin, chief executive of the ICR, said: “This new treatment is highly innovative because it finds a way to direct natural killer cells within the immune system to tumours without requiring complex and expensive re-engineering of a patient’s own cells.

“So far, we’ve only seen initial findings in a small group of patients, but the results look promising, and we’re optimistic that this could be a new type of immunotherapy for cancers that are otherwise hard to treat.”

The trial’s UK lead Dr Juanita Lopez, from the ICR and consultant medical oncologist at the Royal Marsden, said: “This treatment is still highly experimental and our trial is at an early stage, but we are excited by its potential.”