AstraZeneca has signed an agreement with Johnson & Johnson to co-promote the latter's prostate cancer drug Zytiga in Japan.

Zytiga (abiraterone) was approved by the US Food and Drug Administration in April 2011, and in Europe five months later for the treatment of patients with metastatic castration-resistant prostate cancer. The drug, an inhibitor of the CYP17 enzyme, has already become a big-seller, contributing $395 million to J&J's coffers in the second quarter, up 70.3%.

Currently the main treatment option in Japan is medical castration, noted AstraZeneca, although prostate cancer can still progress in many patients because androgens are produced in other tissues. J&J"s Janssen Pharmaceuticals KK unit submitted a marketing approval application for abiraterone to the Japanese Ministry of Health, Labour and Welfare in July this year.

Marc Dunoyer, head of global products and portfolio strategy at AstraZeneca, said that Japan is one of the fastest-growing pharmaceutical markets, where the company "has a proven track record of successfully developing and marketing innovative medicines". He added that abiraterone is "a great addition to our existing portfolio of leading cancer treatments", saying the deal is "a strong strategic fit for AstraZeneca, reinforcing both our focus on oncology as a core therapy area and Japan as one of our key growth drivers".

Financial terms of the agreement have not been disclosed.