Study to Assess Efficacy and Safety of Anti-von Willebrand Factor Nanobody in Patients With Acquired Thrombotic Thrombocytopenic Purpura (TTP)

Inclusion Criteria:

- 18 years of age or older

- Men or women willing to accept an acceptable contraceptive regimen

- Patients with clinical diagnosis of TTP

- Necessitating plasma exchange (one, single PE session prior to randomisation into the
study is allowed)

- Patient accessible to follow-up

- Obtained, signed and dated informed consent

Exclusion Criteria:

- Platelet count greater or equal to 100,000/µL

- Severe active infection indicated by sepsis (requirement for pressors with or without
positive blood cultures)

- Clinical evidence of enteric infection with E.coli 0157 or related organism

- Anti-phospholipid syndrome

- Diagnosis of disseminated intravascular coagulation (DIC)

- Pregnancy or breast-feeding

- Haematopoietic stem cell or bone marrow transplantation-associated thrombotic
microangiopathy

- Known congenital TTP

- Active bleeding or high risk of bleeding

- Uncontrolled arterial hypertension

- Known chronic treatment with anticoagulant treatment that can not be stopped safely

- Severe or life threatening clinical condition other than TTP that would impair
participation in the trial

- Subjects with malignancies resulting in a life expectation of less than 3 months

- Subjects with known or suspected bone marrow carcinosis

- Subjects who cannot comply with study protocol requirements and procedures

- Known hypersensitivity to the active substance or to excipients of the study drug

- Severe liver impairment, corresponding to grade 3 toxicity defined by the CTCAE
(common terminology criteria for adverse events) scale

- Severe chronic renal impairment