BioInvent, ThromboGenics bloodthinner fails to beat Xarelto

Shares went into meltdown mode at a pair of European biotechs today on news that their head-to-head study of an experimental bloodthinner backfired. An increase in bad bleeding incidents among patients on the companies' candidate, TB-402, compared with those on the approved Xarelto prompted the developers to end the mid-stage study and abandon the program altogether.

Belgian biotech ThromboGenics' shares slid a record 21%, and more than half the value of Lund, Sweden-based BioInvent International's shares vanished in trading Tuesday, Bloomberg reported earlier this morning. In a tandem of bad news events, the companies also announced that Roche ($RHHBY) ended a licensing pact with the two companies for the experimental antibody TB-403, which has been studied to stymie the growth of blood vessels to treat cancer and eye diseases.

In the head-to-head study for TB-402, the companies said, the experimental drug was slightly less effective than Bayer and Johnson & Johnson's ($JNJ) Xarelto in preventing blood vessel clots in patients undergoing elective hip and knee surgeries. Yet it was the "significantly" higher bleeding events in patients on TB-402 that pushed the companies to hit the brakes on the program. Such are the potential perils of aggressive drug-development programs, yet at least the companies know now rather than after a larger Phase III study that TB-402 isn't a winner.

"In our collaboration with ThromboGenics we decided to raise the bar for TB-402 by pitching it in a head-to-head trial against Xarelto. Investment decisions should be based on business context and solid science," Svein Mathisen, CEO of BioInvent, said in statement. "In this disappointment it is comforting to know that we did get a clear answer. As we face a number of important data points later this summer both in our collaboration with Genentech as well as in the study of our proprietary multiple myeloma drug it is this principle which guides us.''

- here's the release
- read Bloomberg's article
- here's more on the termination of the Roche pact

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