Pfizer dumps a hemophilia pact with Catalyst, threatening a merger with Targacept

Six years after Catalyst Biosciences inked a $500 million-plus deal to develop Factor VIIa therapies for hemophilia, Pfizer ($PFE) is walking away from the pact it inherited from Wyeth. And now Targacept, which just struck a reverse merger pact to get Catalyst on to the public market, is considering the implications for their tie-up after the biotech's stock took a nasty dive as news of the breakup spread.

Targacept ($TRGT) spotlighted the end of the Catalyst/Pfizer development deal in a regulatory filing earlier this week, which landed a little more than a month after the troubled biotech had struck its merger agreement. The merger would have left Catalyst in charge of the combined entity with 65% of the stock. Targacept's entire R&D platform on nicotinic receptors has essentially collapsed after a string of clinical-stage failures forced AstraZeneca out of its once-close partnership with the company.

"Upon the June 1, 2015, effective date of the termination, the license and certain rights under the research and license agreement will terminate and revert to Catalyst," Targacept noted in a filing with the SEC. "Catalyst has informed Targacept that Pfizer is committed to an orderly transfer of data, regulatory documentation and related technology under the agreement to Catalyst to enable Catalyst to continue the clinical development of this product candidate. Targacept is currently reviewing the implications of this event on the proposed merger."

Catalyst CEO Nassim Usman

The disintegration of the pact couldn't come at a worse time for Catalyst. Asked for a response, Catalyst CEO Nassim Usman told FierceBiotech: "Catalyst remains committed to the FVIIa program."

A month ago Usman told FierceBiotech that their Pfizer-partnered drug, PF-05280602, had just completed a four-year Phase I study. The data have not yet been published, but Usman called it a success, adding that Pfizer was actively at work on plans for taking the next step. That process ended about a week ago, though, as the company was handed a notice of Pfizer's exit.

Catalyst works with protease-based product candidates through "multiple future value inflection points." And in addition to their Factor VIIa program the biotech plans to complete a proof-of-concept study of CB 2679d, a Factor IX biobetter for hemophilia B patients, as well as further development of its novel Factor Xa variant. The biotech had planned to list as $CBIO once the merger was complete.

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