Hemophilia A is caused by a deficiency in blood coagulation Factor (F)VIII. Treatment for acute bleeding in patients comprises prophylactic infusion with human plasma-derived (pd) or recombinant (r)FVIII to increase circulating FVIII levels. However, alloantibodies (inhibitor) may arise in patients, limiting the efficacy of replacement therapy, especially in patients who develop high-titer inhibitors. For these patients, FVIII-bypassing agents are proposed, but there is a rare risk of thrombotic events. Porcine pdFVIII successfully achieves hemostatic FVIII levels in patients in whom human FVIII was ineffective, but possible residual viral contamination and immunogenicity prevents routine use. OBI-1, being developed by Ipsen and Inspiration Biopharmaceuticals Inc, is a bioengineered form of porcine rFVIII that is highly purified. OBI-1 has the procoagulant and biochemical properties of porcine pdFVIII, with improvements in risk of toxicity, infection and ease of manufacture. OBI-1 demonstrated significantly less immunogenicity than pdFVIII in a murine model of hemophilia A. Moreover, in cynomolgus monkeys, OBI-1 did not generate detectable inhibitors. OBI-1 was effective in a phase II, open-label clinical trial in patients with hemophilia A and inhibitor against porcine FVIII, who were experiencing a non-life or -limb threatening bleed. OBI-1 was well tolerated, without drug-related serious adverse events and is promising for further studies.