Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial

Abstract

Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF-binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post-rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved.

Trial registration: ClinicalTrials.gov NCT00816660.

Figures

Figure 1

VWF:RCo, VWF:Ag, and FVIII:C over time after administration of rVWF-rFVIII vs pdVWF-pdFVIII.

Figure 2

PK for subjects with specific pretreatment nonneutralizing anti-VWF–binding antibodies. Subject #21: (A) VWF:Ag after pdVWF-FVIII infusion, (B) VWF:Ag after rVWF-rFVIII infusion, (C) VWF:RCo after rVWF-rFVIII infusion, and (D) FVIII:C after rVWF-rFVIII infusion. Subject #23: (E) VWF:Ag after rVWF-rFVIII infusion, (F) VWF:RCo after rVWF-rFVIII infusion, and (G) FVIII:C after rVWF-rFVIII infusion.

Figure 3

VWF multimers and degradation products postinfusion of rVWF-rFVIII. Dotted horizontal lines indicate the zone where bands of ULMW multimers appear. Due to limitations in space, it was not possible to run all samples taken from a single patient during the PK study on 1 gel. Therefore, to show the distribution of multimers and fragments over time, it was necessary to combine different gels into 1 picture. Vertical lines have been inserted to indicate repositioned gel lanes. (A) Typical VWF multimer pattern (upper gels; low-resolution agarose [1% Seakem]; samples adjusted to VWF:Ag content) and fragments cleaved by ADAMTS13 (lower gels; SDS-PAGE followed by immunoblot with polyclonal anti-VWF antibody; samples were applied undiluted) postinfusion of rVWF-rFVIII. (B) Typical VWF multimer pattern (upper gels; low-resolution agarose [1% Seakem]; samples adjusted to VWF:Ag content) and fragments cleaved by ADAMTS13 (lower gels; patient plasma diluted to 0.05 VWF:Ag U/mL with VWD plasma; 0.025 mU VWF:Ag per lane applied) postinfusion of pdVWF-pdFVIII. (C) Subject #21, with specific pretreatment nonneutralizing anti-VWF–binding antibodies (upper gels: low-resolution agarose [1% Seakem]; samples adjusted to VWF:Ag content; lower gels: SDS-PAGE followed by immunoblot with polyclonal anti-VWF antibody; samples were applied undiluted). (D) Subject #23, with specific pretreatment nonneutralizing anti-VWF–binding antibodies.