JOHNSON & Johnson said yesterday it would buy Aragon Pharmaceuticals, a private company that is running a mid-stage clinical trial for a prostate cancer drug, for US$650 million in cash upfront and a possible second payment of US$350 million if it meets certain milestones.

The deal does not include development of Aragon's treatment for breast cancer, which will be spun off into a separate company called Seragon Pharmaceuticals ahead of the deal and will be run by Aragon's chief executive. The acquisition includes Aragon's most advanced drug, ARN-509, which is now being evaluated as a treatment for prostate cancer, it said.