Combination of new prostate cancer drugs can extend life for men

Combing two new prostate cancer drugs could increase the number of men who respond to treatment and the length of time they benefit, research led by The Institute of Cancer Research (ICR) has shown.

For many years, the only effective treatment for men with advanced prostate cancer who had become resistant to standard hormone therapies was the chemotherapy docetaxel.

Recent trials led by the ICR and The Royal Marsden NHS Foundation Trust have since found that two new types of hormone-blocking drugs, abiraterone acetate and MDV3100, can extend life for men with advanced prostate cancer. Thanks to these trials, abiraterone, which was discovered at the ICR in what is now the Cancer Research UK Cancer Therapeutics Unit, has now been licensed in the US and Europe, while the manufacturers of MDV3100 will apply for approval later this year.

A new study published in Cancer Research has today identified a reason why men ultimately develop resistance to abiraterone. In a laboratory study, Dr Gerhardt Attard from the ICR and The Royal Marsden and colleagues found that steroids and other drugs given in combination with abiraterone to control side-effects could contribute to resistance by activating mutations in the hormone-receptor gene.

Importantly, the team found that it was possible to block this activation by combining abiraterone with MDV3100. This is the first ever study to give a biological reason for combining these two new drugs.

Lead author Dr Attard says: "Abiraterone is an effective treatment for the majority of men with advanced prostate cancer, but sadly they all eventually develop resistance. Our study suggests we should combine prostate cancer drugs rather than giving them sequentially. If the results hold true it patients, this could delay drug resistance and also increase the number of men who benefit. Clinical trials are now being planned to test the combination of abiraterone and MDV3100."

The scientists also found that at high doses, abiraterone could also block the androgen receptor like MDV3100 does.

Study co-author Professor Johann de Bono from the ICR and The Royal Marsden says: "Abiraterone is normally given at 1000mg/day but it is safe at double this dose, and at this level it may have a similar ability to block resistance, so this is another promising avenue to explore. Around 10,000 men a year in the UK are diagnosed with advanced prostate cancer and so our findings have the potential to benefit thousands of men."

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