Pharmacokinetics and safety of OBI-1, a recombinant B domain-deleted porcine factor VIII, in subjects with haemophilia A

OBI‐1 is a recombinant B‐domain deleted porcine factor VIII (FVIII). FVIII treatment in those with haemophilia A may be complicated by the development of anti‐FVIII antibodies (inhibitors) leading to a failure to respond to treatment with human FVIII. To compare the pharmacokinetics and safety of a single dose of OBI‐1 with Hyate:C in subjects with haemophilia A and inhibitors, subjects were randomized to receive either Hyate:C followed by placebo or placebo followed by OBI‐1 in a double‐blind fashion. FVIII levels were assayed using both a one‐stage coagulation assay (OSCA) and chromogenic assay. Pharmacokinetic parameters for FVIII were calculated for 6/9 subjects randomized; in three subjects baseline anti‐porcine FVIII inhibitors led to a lack of measurable FVIII activity. Mean Cmax appeared higher for OBI‐1 (OSCA: 176.00 U dL−1, standard deviation ± 88.00; chromogenic: 151.00 ± 31.51 U dL−1) than Hyate:C (OSCA: 82.3 ± 19.22 U dL−1; chromogenic: 52.67 ± 13.8 U dL−1). Mean AUC also appeared higher for OBI‐1 (OSCA: 2082.87 ± 1323.43 U h−1dL−1; chromogenic: 1817.28 ± 625.14 U h−1dL−1) than Hyate:C (OSCA: 1177.8 ± 469.49 U h−1dL−1; chromogenic: 707.61 ± 420.05 U h−1dL−1). Two infusion‐related events occurred: one with Hyate:C, one with placebo. Four of five subjects without anti‐porcine FVIII inhibitors at baseline remained porcine FVIII inhibitor negative 29 days after infusion. A single dose of OBI‐1 appears to have higher bioavailability than Hyate:C in subjects with haemophilia A without measurable anti‐porcine FVIII inhibitors, and is well tolerated. These results should be confirmed in a larger phase 2/3 study.