A Study of TAK-755 (rADAMTS13) With Little to No Plasma Exchange (PEX) Treatment in Adults With Immune-mediated Thrombotic Thrombocytopenic Purpura (iTTP)

A Phase 2b, Multicenter, Randomized, Double-blind Study of Safety and Efficacy of TAK-755 (rADAMTS13) With Minimal to No Plasma Exchange (PEX) in the Treatment of Immune-mediated Thrombotic Thrombocytopenic Purpura (iTTP)

This is a study of TAK-755 in adults with immune-mediated thrombotic thrombocytopenic purpura (iTTP). The main aim of this study is to determine the percentage of participants with a clinical (Part 1) or platelet (Part 2) response without plasma exchange during the study. Participants who have an acute attack of iTTP will receive TAK-755 and immunosuppressive therapy during their stay at the hospital until they achieve a clinical response in Part 1 or platelet response in Part 2. Participants will also be treated with TAK-755 for an additional time of up to 6 weeks after the acute phase. In total, participants will stay in the study for approximately 3 months.

This study consists of 2-parts. Part 1 is a double-blind, randomized study in which participants were randomized 1:1, in a blinded fashion, into 2 TAK-755 dose groups. Part 1, randomization was stratified based on whether the participant had received pre-study PEX and on the participant's Glasgow Coma Scale. Part 2 is an open-label study in which participants with iTTP experiencing an acute iTTP episode will be enrolled and assigned to a single-arm treatment.

Key Inclusion Criteria (Part 1 and Part 2)

1. Participant must provide a signed informed consent form. A fully recognized proxy may be used per local laws for participants unable to provide consent.
2. Participant is 18 years or older at time of screening.
3. Participant has been diagnosed with de novo or relapsed iTTP.
4. Participant must be willing to fully comply with study procedures and requirements.
5. Female participants of childbearing potential must present with a negative pregnancy test and agree to employ highly effective birth control measures for duration of study. Sexually active male participants must agree to use an effective method of contraception for the duration of the study.

Key Exclusion Criteria (Part 1 and Part 2)

1. Participant has received more than 2 pre-study PEX prior to randomization in Part 1 or first dose of investigational product in Part 2.
2. Participant has been diagnosed with cTTP or another cause of thrombotic microangiopathy (TMA).
3. Participant has been exposed to another investigational product within 30 days prior to enrollment or is scheduled to participate in another clinical study involving investigational product or investigational device during the course of the study.
4. Participant has received caplacizumab within 30 days prior to study enrollment.
5. Participant has had a previous iTTP event within the past 30 days.
6. Participant is positive for human immunodeficiency virus (HIV) with unstable disease or cluster of differentiation (CD)4+ count ≤200 cells/mm^3 within 3 months of screening.
7. Participant has condition of severe immunodeficiency.
8. Participant has a severe systemic acute infection.
9. Participant has another underlying progressive fatal disease and/or life expectancy <3 months.
10. Participant is identified by the investigator as being unable or unwilling to cooperate with study procedures.
11. Participant is pregnant or lactating.
12. Participant has any condition in which methylprednisolone or other steroid equivalent is contraindicated as per prescribing information.
13. Participant has known life-threatening hypersensitivity reaction, including anaphylaxis, to the parent molecule ADAMTS13, Chinese hamster ovary (CHO) cell proteins, or other constituents of TAK-755.