Scios Inc. regained full rights to Natrecor following Bayer Corp.'s decision to back out of their collaboration to develop the hormone-based therapy for acute congestive heart failure.

The companies had been collaborating since May 1998, when Bayer paid $20 million up front in a potential $60 million deal that gave Bayer significant rights to the drug. Another $20 million would have been paid in milestones had the drug received FDA approval. But after a narrow recommendation for approval by an FDA advisory committee, the agency in April refused to approve Natrecor.

"We will continue to work to get the drug approved and will work on potentially getting a new partner," said Wendy Carhart, senior manager, investor relations at Mountain View, Calif.-based Scios. "We are not very concerned about getting a new partner since Natrecor is closer to the finish line than it was when Bayer came on."

Bayer, of Leverkusen, Germany, told Scios its decision to end the collaboration was due to the additional time that will be needed for approval as well as is own portfolio considerations, Carhart said.

The FDA wants Scios to run a larger Phase III trial, and wants further evidence of the drug's safety and effectiveness, she said, adding that Scios is working with the FDA on the design of a new trial.

The final $20 million in milestones in the $60 million deal would have been paid upon approvals in Europe and Japan. Scios had an option to co-promote Natrecor in the U.S. after three years, and would have received additional payments based on annual sales. (See BioWorld Today, May 27, 1998, p. 1.; Feb. 2, 1999, p. 1.; and April 29, 1999, p. 1.)

Scios' stock (NASDAQ:SCIO), which had fallen 61 percent to $3.81 when the FDA failed to approve the drug in April, closed Thursday at $3.187, down 34.38 cents per share. - Jim Shrine