PEGylation extends the prophylactic efficacy of FVIII in the tail vein transection bleeding model of HemA mice. HemA mice received tail vein injection of 40 IU/kg full-length rFVIII (n = 28), 60-kDa diPEG-L491C/K1804C (n = 28), 60-kDa diPEG-F129C/K1804C (n = 20), or excipient (n = 36). Forty-eight hours later, a lateral tail vein was transected, and the moribundity was monitored hourly for the first 11 hours then at 24 hours. Two-tailed P values are generated by log-rank tests comparing the respective survival curves. TVT indicates tail vein transection.