A Study of BAX 930 in Children, Teenagers, and Adults Born With Thrombotic Thrombocytopenic Purpura (TTP)
A Study of BAX 930 in Children, Teenagers, and Adults Born With Thrombotic Thrombocytopenic Purpura (TTP)
Thrombotic thrombocytopenic purpura (or TTP for short) is a condition where blood clots form
 in small blood vessels. This means the cells that help the blood to clot (platelets) are
 lower in the blood, which can lead to bleeding just under the skin. Some people are born with
 this condition, others get the condition during their life. BAX 930 is a medicine to either
 prevent bleeding or control bleeding in people born with severe TTP.

 The main aim of this study is to compare the number of bleeds in people born with severe TTP
 when they treated with BAX 930 in 2 ways:

 -  BAX 930 given to prevent bleeding from happening.

 -  BAX 930 given to control bleeding when it happens, according to the clinic's standard
 practice.

 Another aim is to check for side effects from treatment with BAX 930.

 At the first visit, the study doctor will check who can take part. Some participants who can
 take part will only be treated with BAX 930 to control bleeding when it happens. Other
 participants who can take part will be picked for 1 of 2 groups by chance.

 Both groups will be treated with BAX 930 to prevent bleeding and to control bleeding when
 they happen but in a different order. All participants will receive BAX 930 slowly through a
 vein (infusion).

 One group will receive BAX 930 every 2 weeks to prevent bleeding, then will receive BAX 930
 to control bleeding when they happen. The other group will receive BAX 930 to control
 bleeding when they happen, then will receive BAX 930 every 2 weeks to prevent bleeding. Both
 treatments will last for 6 months.

 The study doctors will check how long BAX 930 stays in the blood of the participants, over
 time. They will do this from blood samples taken after participants receive their specific
 infusions of BAX 930. This will happen at 3 different times during the study.

 1 month after all treatment has been completed, participants will visit the clinic for a
 final check-up.
Inclusion Criteria:

 -  Participant or legally authorized representative has provided signed informed consent
 greater than or equal to (>=) 18 years of age and/or assent form (signed by legal
 representative if participants is less than (<) 18 years of age).

 -  Participant is 0 to 70 years of age, inclusive, at the time of screening.
 (Participants < 18 years of age will be enrolled only after at least 5 adults (>= 18
 years of age) each have at least 10 exposures with BAX 930 and reviewed by the Data
 Monitoring Committee (DMC). In France, no participants younger than 18 years of age
 will be enrolled into the study before the first adult participant has been treated
 with BAX 930 for a minimum of 6 months.

 -  Participant has a documented diagnosis of severe hereditary ADAMTS13 deficiency,
 defined as:

 -  Confirmed by molecular genetic testing, documented in participant history or at
 screening, and

 -  A disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13
 (ADAMTS13) activity < 10 percent (%) as measured by the fluorescent resonance
 energy transfer- von Willebrand factor73 (FRETS-VWF73) assay, documented in
 participant history or at screening (participants currently receiving standard of
 care (SoC) prophylactic therapy may exceed 10% ADAMTS13 activity at screening).

 Note: Participants currently receiving prophylactic therapy will be screened immediately
 prior to their usual prophylactic infusion

 -  Participant does not display any severe thrombotic thrombocytopenic purpura (TTP)
 signs (platelet count < 100,000/ microliter (mcL) and elevation of lactate
 dehydrogenase (LDH) greater than (>2)*upper limit of normal (ULN)) at screening.
 (Prophylactic cohort only).

 -  Participant is currently on a prophylactic dosing regimen or has a documented history
 of at least 1 TTP event and an ability to tolerate SoC prophylactic dosing
 (prophylactic cohort only).

 -  Participants >= 16 years of age must have a Karnofsky score >= 70% and participants <
 16 years of age must have a Lansky score >= 80%.

 -  Participant is hepatitis C virus (HCV)-negative as confirmed by antibody or polymerase
 chain reaction testing OR HCV-positive if their disease is chronic but stable.

 -  If female of childbearing potential, participant presents with a negative blood or
 urine pregnancy test, confirmed no more than 7 days before the first administration,
 and agrees to employ adequate birth control measures for the duration of the study and
 to undergo quarterly pregnancy testing.

 -  Sexually active males must use an accepted and effective method of contraception
 during the treatment and until a minimum of 16 days after the last dose administered.

 -  Participant is willing and able to comply with the requirements of the protocol.

 Exclusion Criteria:

 -  Participant has been diagnosed with any other TTP-like disorder (microangiopathic
 hemolytic anemia), including acquired TTP.

 -  Participant has known hypersensitivity to hamster proteins.

 -  Participant has experienced an acute TTP episode less than 30 days prior to screening
 (prophylactic cohort only).

 -  Participant has a medical history or presence of a functional ADAMTS13 inhibitor at
 screening.

 -  Participant has a medical history of genetic or acquired immune deficiency that would
 interfere with the assessment of product immunogenicity, including participants who
 are human immunodeficiency virus (HIV)-positive with an absolute cluster of
 differentiation 4 (CD4) count < 200/ cubic millimeter (mm^3) or who are receiving
 chronic immunosuppressive drugs.

 -  Participant has been diagnosed with severe cardiovascular disease (New York Heart
 Association classes 3 to 4).

 -  Participant with end stage renal disease requiring chronic dialysis.

 -  Participant has been diagnosed with hepatic dysfunction, as evidenced by, but not
 limited to, any of the following:

 -  Serum alanine aminotransferase (ALT) >= 2* upper limit of normal (ULN).

 -  Severe hypoalbuminemia < 24 gram per liter (g/L).

 -  Portal vein hypertension (e.g., presence of otherwise unexplained splenomegaly,
 history of esophageal varices).

 -  In the opinion of the investigator, the participant has another clinically significant
 concomitant disease that may pose additional risks for the participant.

 -  Participant has been treated with an immunomodulatory drug, excluding topical
 treatment (e.g., ointments, nasal sprays), within 30 days prior to enrollment. Use of
 corticosteroids in conjunction with administration of fresh frozen plasma (FFP) to
 prevent allergic manifestations is permitted.

 -  Participant has an acute illness (e.g., influenza, flu-like syndrome, allergic
 rhinitis/conjunctivitis, bronchial asthma) at the time of screening (prophylaxis
 cohort only).

 -  Participant is receiving or anticipates receiving another investigational drug and/or
 interventional drug within 30 days before enrollment.

 -  Participant has a history of drug and/or alcohol abuse within the last 2 years.

 -  Participant has a progressive fatal disease and/or life expectancy of less than 3
 months.

 -  Participant is identified by the investigator as being unable or unwilling to
 cooperate with study procedures.

 -  Participant suffers from a mental condition rendering him/her unable to understand the
 nature, scope, and possible consequences of the study and/or evidence of an
 uncooperative attitude.

 -  Participant is a family member or employee of the sponsor or investigator.

 -  If female, participant is pregnant or lactating at the time of enrollment.

 -  Any contraindication to SoC medicinal product(s) as per local prescribing information.