Prostate patients’ tumours shrink in ‘remarkable’ trial of new treatment

‘Extraordinary’ trials have shown that a new treatment for advanced prostate cancer can stop and even shrink tumors.

Early tests of immunotherapy, which uses the body’s immune system to fight cancer, showed a reduction in the disease in almost half of the men.

Until now, this type of treatment has not been proven effective in prostate cancer patients; There was little reduction in tumors or serious side effects.

But the new drug, known as VIR-5500, uses a ‘cloaking device’ to ensure it does not activate until it reaches the tumour, helping to prevent side effects.

Experts said this raises hope of a cure ‘in the not too distant future’ for people whose cancer has already spread.

Prostate cancer is the most common cancer among British men, with 55,000 new cases a year. Featured patients include Olympic cycling champion Sir Chris Hoy, 49, who is living with a terminal diagnosis.

Researchers led by the Institute of Cancer Research (ICR) and the Royal Marsden NHS Foundation Trust tested 58 men with advanced prostate cancer that had stopped responding to other treatments.

The team, led by Professor Johann de Bono, saw that almost half (45 percent) of the patients’ tumors shrank.

Meanwhile, 88 percent of patients from eight sites around the world experienced only very mild side effects, according to findings presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco.

Half (53 percent) of the 17 patients given the highest dose of the drug found that their prostate-specific antigen (PSA) levels, a blood marker of prostate disease, dropped by 90 percent. And 82 percent saw them halved.

The drug, known as a ‘T cell binder’, works by binding to T cells in the body’s immune system and a protein found in prostate cancer cells. When it binds to cancer cells – wherever they are – it brings T cells into contact with them, enabling the attack.

According to research funded by Vir Biotechnology, the drug’s ‘cloaking device’ also allows the drug to remain in the bloodstream for longer; This means fewer doses are needed.

Professor Johann de Bono said that the drug will now move on to larger trials. He added: ‘There is certainly hope that drugs like this will increase the likelihood of treating even advanced prostate cancer that has already spread in the not-too-distant future.’

The Daily Mail has been campaigning for better prostate cancer treatment for more than two decades.