Immunotherapy success in prostate cancer

The immunotherapy agent pembrolizumab has shown positive results in men with advanced prostate cancer who had run out of treatment options.

The trial of 258 men with advanced disease found around 38 per cent were still alive after a year, while 11 per cent did not see the cancer grow when treated with the checkpoint inhibitor pembrolizumab.

The full results of the trial, led by a team at the Institute of Cancer Research, London, and the Royal Marsden NHS Foundation Trust, will be presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago.

Immunotherapy works by kick-starting the immune system to identify cancer cells and is already successfully used in other cancers, including melanoma. However, this is the first time it has been found to be effective in prostate cancer

One of the trial leaders, Professor Johan de Bono, says: ‘In the last few years immunotherapy has changed the way we treat many advanced cancers – but up to now no one had demonstrated a benefit in men with prostate cancer.

Our study has found that immunotherapy can benefit a subset of men with advanced, otherwise untreatable prostate cancer, and these are most likely to include patients who have specific DNA repair mutations within their tumours.’

Only five per cent of men in the trial saw their tumours shrink or disappear after treatment but many of those had mutations in genes involved in repairing DNA in their tumours.

The researchers suggest these mutating cancer cells may be easy for the immune system to recognise and attack because they look different from healthy cells.

Professor de Bono said: ‘We are planning a new clinical trial, specifically in men with prostate cancer whose tumours have mutations in DNA repair genes, to see if immunotherapy can become a standard part of their treatment.’

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