According to recent trials led by The Institute of Cancer Research (ICR) (UK) and The Royal Marsden (UK) combining Zytiga (abiraterone acetate) with the yet FDA unapproved investigational drug MDV3100 could increase the number of men, with advanced prostate cancer, who respond to treatment as well as the length of time they benefit.
A new study published today in Cancer Research has identified a reason why men with metastatic prostate cancer ultimately develop resistance to Zytiga. In a laboratory study, Dr Gerhardt Attard and colleagues found that the steroids that are given in combination with the Zytiga to control side effects could be contributing to the development of resistance by activating mutations in the hormone receptor gene.
The really interesting finding they have made is that it was possible to block this activation by combining Zytiga with MDV3100.
Dr Attard said, “Abiraterone (Zytiga) 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 when administered at high doses, Zytiga could also block the androgen receptor like Casodex and MDV3100.
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.
Joel T Nowak, M.A., M.S.W.