By Randall Osborne

After disappointing results from a Phase I trial with an undisclosed oral thrombin inhibitor, Corvas International Inc. and Schering-Plough Corp. agreed to end their collaboration in that area, but two other deals remain in effect.

"You expect some failures," said Gwenetta Como, spokeswoman for San Diego-based Corvas. "We gave it our best shot."

Corvas partnered with Madison, N.J.-based Schering-Plough in 1994 to develop and commercialize anti-thrombotic drugs to prevent and treat cardiovascular disorders. As part of the potential $80 million agreement, Schering-Plough had an option — which it exercised — to expand the program to cover another blood-coagulation enzyme inhibitor, known as Factor Xa. (See BioWorld Today, Dec. 20, 1994, p. 1.)

"It's in lead optimization," Como told BioWorld Today. "We're finding the best compound to move forward into Phase I, and we expect maybe by the end of this year, we'll have a candidate selected."

The unnamed drug that failed at Phase I was initially the program's lead thrombin inhibitor. In the research and development phase of their collaboration, Corvas received $17 million in equity and milestone payments from Schering-Plough.

"The contract called for $41.5 million [from thrombin inhibitors]," Como said. "All that was left was more milestone payments."

With Schering-Plough, Corvas also is moving ahead with a program in hepatitis C inhibitors, now in the preclinical stage. Corvas has an anti-coagulant, NAPc2, expected to enter Phase II trial later this year. Another compound, neutrophil inhibitory factor, is being developed by Pfizer Inc., of New York, for ischemic stroke.

"We don't have all our eggs in one basket," Como said.

Corvas' stock (NASDAQ:CVAS) closed Monday at $3.375, down $0.25. *