New study shows drug combats previously untreatable prostate cancers  

New, groundbreaking research reveals a drug, discovered at The Institute of Cancer Research, could treat up to 80% of patients with aggressive previously drug-resistant prostate cancer, according to a study published in the Journal of Clinical Oncology.

The results of the Phase 1 clinical trial, undertaken by The Institute of Cancer Research and The Royal Marsden Hospital, found that the drug abiraterone could treat up to 10,000 British men diagnosed each year with the most aggressive and almost always fatal type of prostate cancer.

The study revealed significant tumour shrinkage and dramatic falls in PSA levels in the majority of advanced prostate cancer patients who received the drug.

Lead researcher Dr Johann de Bono said the drug abiraterone worked to block the generation of key hormones that drive the growth of prostate cancers.

"Clinical benefits included evidence of PSA falls and tumour shrinkage which was observed in 70-80 per cent of patients," he said.

"Abiraterone works not only in blocking the generation of these hormones in the testes, but also elsewhere in the body, including generation of hormones in the cancer itself.

"Tumour shrinkage was determined by a reduction in the blood level of prostate specific antigen (PSA) – a protein associated with prostate cancer activity, and also with analyses of CAT scans, MRI scans and bone scans.

"The Royal Marsden patients in this study have been monitored for up to two-and-a-half years and with continued use of abiraterone they were able to control their disease with few side-effects. A number of patients were able to stop taking morphine for the relief of bone pain.

"These men have very aggressive prostate cancer which is exceptionally difficult to treat and almost always proves to be fatal. We hope that abiraterone will eventually offer them real hope of an effective way of managing their condition and prolonging their lives.

"It is envisioned that this drug will be available for general use from 2011 and we hope it can become widely available. In the interim, it is available through clinical trials only."

All the patients involved in the trial had an aggressive form of prostate cancer in which the tumour tissue is believed to be able to produce its own supply of the hormones which drive tumour growth. This form cannot be solely treated with currently available drugs to block the production of male hormones by the testes.

Abiraterone works via a different mechanism which blocks the synthesis of male hormones in all tissues. The drug may eventually be used alongside other treatments in patients with the "castration-resistant" aggressive form of the disease.

Abiraterone is owned by BTG and licensed to Los Angeles based Cougar Biotechnology. It is now undergoing further clinical trials including a 1200-patient international study for the treatment of men with prostate cancer. Abiraterone is also being used to treat breast cancer in women through a Cancer Research UK funded trial.

Cally Palmer, Chief Executive of The Royal Marsden NHS Foundation Trust, said: "The results of this study show just how important abiraterone is set to become in the treatment of men with prostate cancer and highlights the national importance of funding pioneering cancer research."