Sponsor decided not to go forward with the study.

To evaluate the effect of ARC1779, a therapeutic oligonucleotide ("aptamer") in patients with Type2B von Willebrand Disease.

ARC1779 will be investigated in an open-label, uncontrolled study in up to 3 vWD-2B patients. Patients with vWD-2B will be screened for eligibility based primarily upon a single major criterion, i.e., presence of any degree of chronic thrombocytopenia. Eligible patients will be treated by intravenous infusion of ARC1779 for 72 hours.

Inclusion Criteria:

• Male or female patients;
• ≥ 16 to ≤ 75 years of age;
• Diagnosis of VWD-2B according to national expert guidelines for the USA [1] and Europe [2] based on medical history and findings from a matrix of laboratory assays which may include: platelet count, concentration of VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), Factor VIII (FVIII) activity, ristocetin-induced platelet aggregation (RIPA), platelet function analyzer (PFA-100®) closure time, bleeding time (BT), VWF multimer test, VWF: platelet-binding (VWF:PB) activity, etc.)
• Thrombocytopenia (defined as a platelet count < 100 per nL on at least 2 occasions within the month preceding enrollment;
• Female patients of reproductive age must be enrolled within 1 to 7 days of the cessation of preceding menses;
• Female patients must be non-pregnant and willing to use effective, redundant methods of contraception (i.e., for both self and male partner) throughout the study and for at least 30 days after discontinuation of study drug treatment;
• Male patients must agree to use a medically acceptable contraceptive (abstinence or use of a condom with spermicide) throughout the study and for at least 30 days after discontinuation of study drug treatment;
• All patients must be capable of understanding and complying with the protocol and must have signed the informed consent document.

Exclusion Criteria:

• Patients with a possible co-existing or alternative hematologic diagnosis which can account for the laboratory findings of thrombocytopenia, etc.;
• Any significant medical co-morbidity which would pose an increased risk of bleeding (e.g., recent trauma or surgery, a history of gastrointestinal ulcers, etc.) or thrombosis (e.g., history of recurrent deep vein thrombosis (DVT).