New York: Johnson & Johnson (J&J), the world’s biggest maker of health-care products, agreed to buy Aragon Pharmaceuticals Inc. and its experimental prostate cancer drug in a deal worth as much as $1 billion.

Aragon will receive an initial cash payment of $650 million, New Brunswick, New Jersey-based J&J said in a statement on Monday. Additional payments of as much as $350 million may follow if Aragon’s cancer candidate, ARN-509, achieves certain milestones, J&J said.

Aragon’s main experimental prostate cancer drug is in the second of three stages usually required for regulatory approvals in the US and may complement Zytiga, the prostate cancer treatment J&J unveiled two years ago. J&J will receive Aragon’s entire program to develop drugs that block androgen, a hormone that can fuel tumors in the prostate.

“The acquisition of Aragon further enhances our leadership in prostate cancer drug development," said Peter F. Lebowitz, head of oncology research for J&J’s Janssen Research & Development unit, in the statement. “Prostate cancer is one of our main areas of focus, and we are pleased to be adding ARN-509 to our portfolio."

Aragon’s remaining assets will be spun off to a new company called Seragon Pharmaceuticals before the purchase by J&J is completed, San Diego-based Aragon said in a separate statement. J&J won’t have a stake in that venture or rights to any products it might produce.

Johnson & Johnson was the fastest-growing company among large pharmaceutical companies last year, buoyed by eight new medicines that generated $4.4 billion in new sales in 2012. J&J was unchanged in New York trading on 14 June, closing at $84.91. The shares have gained 21% this year. Bloomberg