Recombinant Porcine Factor VIII (OBI-1) for Treating Acquired Hemophilia A
February 28, 2013 | Technology Forecasts
In acquired hemophilia A, the most commonly reported form of acquired hemophilia, an abnormal immune system reaction causes the production of autoantibodies that attack blood clotting factor VIII and make conventional clotting factor VIII replacement therapy (the standard treatment for congenital hemophilia A) ineffective.1,2 Clinicians treat acquired hemophilia A by administering one or more other activated clotting factors (e.g., factor II, VIIa, Xa) to higher-than-normal levels to bypass the normal clotting cascade process.2 This bypass therapy carries the risk of causing overcoagulation (i.e., promoting excessive clot formation) but is currently the only option for overcoming the inhibition of clotting factor replacement therapy.2,3 Acquired hemophilia A is rare, with estimated incidence in the United States between 0.2 and 1 case per million people.4
Inspiration Biopharmaceuticals, Inc. (Cambridge, MA, USA) initially developed OBI-1, an intravenous recombinant porcine factor VIII product that purportedly has low cross-reactivity with autoantibodies against human factor VIII. The company went into bankruptcy in 2012 and in January 2013, Baxter International Inc. announced that would acquire the investigational hemophilia compound OBI-1 and "related assets from Inspiration BioPharmaceuticals, Inc. as well as certain other OBI-1 related assets, including manufacturing operations, from Ipsen Pharma S.A.S."5
According to Inspiration, the product's low cross-reactivity may substantially reduce the likelihood that existing autoantibodies to human factor VIII will inhibit porcine factor VIII, thereby increasing factor VIII replacement therapy's effectiveness.6,7 However, a patient's immune system could still create an immune response to the new therapy by generating a different set of antibodies to porcine factor VIII. The company states that unlike currently available treatments for acquired hemophilia A that bypass autoantibodies to clotting factor VIII, OBI-1 allows normal functioning of the natural clotting pathway. This reduces the risk of overcoagulation and allows clinicians to measure...