Half-life extension of rFVIIIFc is dependent on FcRn. PK profiles of rFVIIIFc and rFVIII in (A) HemA mice, (B) C57BL/6 mice, (C) FcRn KO mice, and (D) human FcRn transgenic Tg32B mice following a tail vein injection of 125 IU/kg. Results shown are mean ± SD from 4 mice per treatment at each time point. The PK parameter estimates are summarized in Table 2.