Patient description: The patient is a 23-year-old man who came to the hospital with high blood pressure (175/95 mmHg) and signs of septicemia. He developed respiratory failure requiring mechanical ventilation and renal failure requiring hemodialysis. His blood smear showed microangiopathic hemolytic anemia and thrombocytopenia. His blood tests revealed elevated lactate dehydrogenase and reduced human complement C3 levels with a normal coagulation profile. He was diagnosed with atypical hemolytic uremic syndrome. He was treated with plasma exchange and corticosteroids. He has been previously vaccinated with meningococcal group ACWY conjugate vaccine and meningococcal group B vaccine. The genetic survey revealed ADAMTS13 >10%.

Clinical trial eligibility criteria: eligible ages (years): 12.0-65.0,  Hereditary Thrombotic Thrombocytopenic Purpura (TTP) Subject is between 12 and 65 years of age, inclusive. (The first 2 subjects in any cohort will be ≥ 18 years of age.) Subject and/or legally authorized representative has provided written informed consent Subject has a documented diagnosis of severe hereditary deficiency, defined as 1) confirmed by genetic testing, documented in patient history or at screening, and 2) activity < 6%, documented in patient history or at screening. NOTE: In patients receiving prophylactic therapy with fresh frozen plasma (FFP) or other containing products, the levels of plasma activity may exceed 6% at screening Cryoprecipitate, FFP, or other containing products interfering with PK have to be paused at least 10 days prior to infusion of the investigational product The subject is not displaying any severe TTP symptoms at screening. Patients presenting with minor, but stable laboratory abnormalities (LDH not higher than 3 times the upper limit of normal; platelet count not lower than 100,000 per μl) at screening may be enrolled Subjects ≥18 years of age have a Karnofsky score ≥ 60%, and subjects < 18 years of age have a Lansky score ≥ 70% Subject is hepatitis C virus negative (HCV-) as confirmed by antibody or polymerase chain reaction (PCR) testing; HCV positive (HCV+) subjects are eligible for if their disease is chronic but stable If female of childbearing potential, subject presents with a negative serum pregnancy test and agrees to employ adequate birth control measures for the duration of the study Subject is willing and able to comply with the requirements of the protocol  Subject has been diagnosed with any other TTP-like disorder (for example, microangiopathic hemolytic anemia), including acquired TTP Subject has known hypersensitivity to hamster proteins or other components of the investigational product Subject has a medical history or presence of a functional neutralizing inhibitor at screening Subject has a medical history of immunological disorders, excluding seasonal allergic rhinitis/conjunctivitis/mild asthma, food allergies or animal allergies Subject has a medical history of hematological disorders, in particular systemic lupus erythematosus, amyloidosis, antiphospholipid antibody syndrome, vasculitis, other hemolytic anemia, disseminated intravascular coagulation, and systemic scleroderma Subject has a history of significant neurological events, such as major stroke, indicating that a relapse might have severe consequences, as judged by the investigator Subject is HIV positive with an absolute CD4 count < 200/mm3 Subject has been diagnosed with a cardiovascular disease [New York Heart Association (NYHA) classes 3-4] Subject is scheduled to undergo elective surgery during study participation Subject has been diagnosed with severe liver disease, as evidenced by, but not limited to, any of the following: serum ALT 3 times the upper limit of normal, international normalized ratio (INR) > 1.5, hypoalbuminemia, portal vein hypertension (e.g. presence of otherwise unexplained splenomegaly, history of esophageal varices)