Baxter International agreed to acquire worldwide rights to OBI-1, a recombinant porcine factor VIII (rpFVIII) for congenital hemophilia A with inhibitors against human FVIII and acquired hemophilia A from the bankrupt Inspiration Biopharmaceuticals and its lead investor, French-owned Ipsen, the sellers said today. Baxter also agreed to buy Ipsen’s OBI-1 manufacturing facility in Milford, MA.

Baxter will pay $50 million up-front, up to $135 million tied to undisclosed development and commercial milestones, as well as tiered net sales payments ranging from 12.5% to 17.5% of OBI-1 annual net sales.

The Baxter acquisitions were formalized in an asset purchase agreement (APA) filed yesterday with U.S. Bankruptcy Court in Boston. Inspiration filed for Chapter 11 protection from creditors in October, nearly four months after the FDA placed clinical trials for its lead drug candidate under clinical hold. Since then, Ipsen agreed to provide Inspiration with up to $18.3 million debtor-in-possession financing, while both companies launched a joint marketing and sale process to shed assets.

Under their APA, Ipsen has agreed to extend up to an additional $5 million in debtor-in-possession funds to Inspiration for 45 days. The APA is subject to Bankruptcy Court and regulatory approvals, among other closing conditions.

Ipsen and Inspiration also said they are in the final bidding stages of selling a second Inspiration drug candidate—IB1001, a recombinant factor IX (rFIX) for treatment and prevention of bleeding in patients with hemophilia B.

For IB1001, as with OBI-1, Ipsen will receive about 60% of the up-front payments, plus 80% of all payments up to $304 million, and half of all proceeds thereafter. Ipsen is Inspiration’s only senior secured creditor, and owns non-Inspiration assets that will be included in the sale of both drug candidates.

Ipsen said the up-front payments will mainly allow it to recoup the debtor-in-possession financing, with additional proceeds contingent on OBI-1’s approval. Ipsen warned it may take an asset impairment charge of about €100 million ($133.6 million) after taxes.

Just a year ago, Inspiration moved from California to Cambridge, MA, and started building up its staff, with never-realized plans for about 100 employees by the end of 2012, and about 150 by end of this year. Ipsen also moved its U.S. headquarters cross-country, from Brisbane, CA, to Bridgewater, NJ, so it could be closer to Inspiration.

But Inspiration’s growth plans were derailed in July, when FDA placed on clinical hold two of Inspiration’s late-stage clinical trials for IB1001—a Phase III trial evaluating IB1001’s safety and efficacy in treating and preventing bleeding episodes in adults with hemophilia B; and a Phase III/IIIb study evaluating IB1001’s safety and efficacy to treat and prevent bleeding episodes in previously treated children with hemophilia B.

The hold came after Inspiration reported to the FDA that, during the course of routine laboratory evaluations, it found that a higher-than-expected proportion of individuals treated with IB1001 had developed antibodies to proteins from the Chinese hamster ovary, or CHO, host cells used to manufacture the therapy.

OBI-1 is the subject of a Phase II/Phase III clinical trial that was recruiting participants as of November, according to a post verified by Inspiration on A second Phase III trial was listed as active but not recruiting patients, also as of November.

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