Researchers believe the approach could mean more patients benefiting from drug treatment and patients responding to therapy for longer.
Dr Gerhardt Attard and colleagues from the Royal Marsden NHS Foundation Trust in London examined why men develop resistance to the hormone-blocking treatment with abiraterone.
The study looked at the possibility that drugs often given alongside abiraterone to control side-effects contribute to the development of resistance.
In cell-based tests, the team of researchers found steroids and other drugs given to treat side-effects contribute to resistance to abiraterone by activating mutations in the hormone-receptor gene.
The team found that it was possible to block this activation using combination treatment with MDV3100, another hormone blocking treatment for prostate cancer.
Commenting on the findings, Dr Attard said: ‘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 in patients, this could delay drug resistance and increase the number of men who benefit. Trials are being planned to test abiraterone and MDV3100.’
Dr Attard and his colleagues also suggested that further studies could examine other approaches to improving treatment responses, such as using higher doses of abiraterone taken with food.