Recombinant VWF(University of Pittsburgh)

The von Willebrand factor (VWF), one of the largest plasma proteins in mammals, is an essential factor in primary hemostasis. It forms a bridge between platelet membrane glycoprotein Ib and extracellular matrix constituents, thereby playing a critical role in platelet adhesion to vascular injury sites. Its deficiency, known as von Willebrand disease is the most common inherited bleeding disorder. VWF is also a carrier protein for blood clotting factor VIII, an interaction required for normal factor VIII survival in circulation. As its symptoms are less severe than those of hemophilia and due to its wide variety, a large number of cases may not have actually been diagnosed. In the selection of therapeutic measures and patient management for bleeding symptoms, introduction of recombinant VWF concentrates is expected to expand the range of therapeutic options.

Von Willebrand disease (VWD) is a congenital bleeding disorder caused by quantitative and qualitative abnormalities in von Willebrand factor (VWF). VWD was first reported in 1926 by Dr. Erik von Willebrand, a Swedish physician, who reported a bleeding disorder in a family. VWD manifests as bleeding from the skin and mucous membranes (abnormal primary hemostasis). The symptoms are less severe than those of hemophilia and may be undiagnosed in many cases. Evidence-based guidelines are required for selection and patient management. Since ristocetin cofactor activity (vWF:RCo) and VWF antigen levels (vWF:Ag) are not routinely measured in clinical laboratories, the actual diagnosis is often determined by a mild prolongation of the activated partial thromboplastic time (APTT) associated with a relative decrease in factor VIII activity. Particularly, it is desirable to provide standard treatment measures on how to introduce the recently proposed bleeding score (BS; clinically scored for various bleeding symptoms of VWD) and how to deal with gynecological symptoms, such as excessive menstruation and irregular vaginal bleeding. In terms of treatment options, recombinant vWF concentrates were introduced in 2020, which has led to the expansion in the range of treatment options for patients.