A Phase 3b, Prospective, Open-label, Multicenter, Single Treatment Arm, Continuation Study of the Safety and Efficacy of TAK-755 (rADAMTS13, Also Known as BAX 930/SHP655) in the Prophylactic and On-demand Treatment of Subjects With Severe Congenital Thrombotic Thrombocytopenic Purpura (cTTP; Upshaw-Schulman Syndrome, or Hereditary Thrombotic Thrombocytopenic Purpura)

  • End date
    Aug 27, 2026
  • participants needed
  • sponsor
Updated on 24 October 2022


Thrombotic thrombocytopenic purpura (or TTP for short) is a condition where blood clots form in small blood vessels throughout the body. The clots can limit or block the flow of oxygen-rich blood to the body's organs, such as the brain, kidneys, and heart. As a result, serious health problems can develop. The increased clotting that occurs in TTP uses up the cells that help the blood to clot, called platelets. With fewer platelets available in the blood, bleeding problems can also occur. People who have TTP may bleed underneath the skin forming purple bruises, or purpura. TTP also can cause anemia, a condition in which red blood cells break apart faster than the body can replace them, leading to fewer red blood cells than in normal.

TTP is caused by a lack of activity in the ADAMTS13 enzyme, a protein in the blood involved in controlling clotting of the blood. The ADAMTS13 enzyme breaks up another blood protein called von Willebrand factor that forms blood clots by clumping together with platelets. Some people are born with this condition, while others develop the condition during their life. Many people who are born with TTP experience frequent flare-ups that need to be treated right away. TAK-755 is a medicine that replaces ADAMTS13 and may prevent or control TTP flare-ups, called acute TTP events.

The main aim of the study is to check for side effects of long-term treatment with TAK-755. Treatment will be given in 2 ways:

  1. TAK-755 treatment given either every week or every other week to prevent acute TTP events from happening (the "prophylactic" cohort).
  2. TAK-755 treatment given to control an acute TTP event when it happens (the "on-demand" cohort).

Participants in the prophylactic cohort will receive treatment in the clinic or at home for up to approximately 3 years. They will visit the clinic at least every 12 weeks. Participants in the on-demand cohort will receive daily treatment for the acute TTP event until the flare-up has gotten better. They will have a follow-up visit at the clinic 4 weeks later.


This is a follow-up study to the Phase 3 pivotal study (281102 [NCT03393975]) and will be comprised of two treatment cohorts (Prophylactic and On-demand) consisting of naïve and non-naïve participants who were born with TTP, with a total duration of approximately 6 years. A maximum of approximately 77 participants will be enrolled in this study (approximately 57 participants who have completed study 281102 [NCT03393975] [non-naïve participants] and at least 20 naïve participants (participants who are naïve to TAK-755). Participants from Expanded Access Programs, participants from study 281102 (NCT03393975) who had an allergic reaction to standard of care treatment, and participants who completed the Phase 1 study (281101 [NCT02216084]) but did not participate in Study 281102, will also be eligible for enrollment in this continuation study as naïve participants.

TAK-755 is given slowly through a vein (intravenous infusion). Participants in the prophylactic cohort will be able to opt for treatment in a home setting by caregiver or self-infusion subject to conditions and to local regulatory approval.

Condition Thrombotic Thrombocytopenic Purpura (TTP)
Treatment TAK-755
Clinical Study IdentifierNCT04683003
Last Modified on24 October 2022


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