Progenics Pharmaceuticals, Inc announced that its collaborator, Ono Pharmaceutical Co, Ltd., Osaka, Japan has begun clinical testing in Japan of Relistor (methylnaltrexone bromide) subcutaneous injection, the first-in-class medicine approved in the US, Canada, the European Union, Australia and Latin American countries for the treatment of opioid-induced constipation. Ono has exclusive rights to subcutaneous Relistor in Japan, where it is pursuing plans to develop and commercialize the drug, designated ONO-3849, for the treatment of opioid-induced constipation. Relistor is being developed and commercialized in the rest of the world by Progenics and Wyeth Pharma, a division of Wyeth.

ONO-3849 is being developed in Japan according to the regulatory agency guidelines of Japan's Ministry of Health, Labour and Welfare, and will be evaluated in Japanese patients with opioid-induced constipation.

"Our collaboration with Ono exemplifies Progenics' corporate strategy of maximizing market access to Relistor through key geographic development and commercialization partnerships," said Paul J Maddon, Progenics' Founder, chief executive officer and chief science officer. "We believe the advancement of Relistor into clinical studies in Japan demonstrates a shared commitment of both organizations to providing patients in Japan who suffer from opioid-induced constipation access to this first-in-class product, if approved."

In October of last year, Progenics announced an agreement by which Ono has rights in Japan to the subcutaneous form of Relistor, and is responsible for developing and commercializing subcutaneous Relistor in Japan, including conducting the clinical development necessary to support regulatory marketing approval. Under the agreement, Progenics received an upfront fee, and is entitled to commercial and development milestones, as well as royalties on sales of Relistor in Japan.

Relistor, administered via subcutaneous injection, is a peripherally acting mu-opioid receptor antagonist that decreases the constipating effects of opioid pain medications in the gastrointestinal tract without affecting their ability to relieve pain.