Abstract Number: PB0837
Meeting: ISTH 2021 Congress
Background: Congenital thrombotic thrombocytopenic purpura (cTTP) is a rare and life-threatening microvascular disease caused by ADAMTS13 deficiency. A recombinant ADAMTS13 (TAK-755 [BAX 930]; Baxalta US Inc., a Takeda company, Lexington, MA, USA) is being developed for use as on-demand and prophylactic ADAMTS13 replacement for patients with TTP.
Aims: We report the design (including recent updates) of a phase 3, prospective, randomized, controlled, open-label, multicenter, crossover study to assess the safety and efficacy of TAK-755 for the prevention and treatment of acute episodes of TTP in patients with severe cTTP (NCT03393975).
Methods: This study will include ~57 patients (aged 0 to 70 years) with severe congenital ADAMTS13 deficiency (defined as plasma ADAMTS13 activity <10%), randomized into 1 of 2 treatment sequences (TAK-755 then standard of care [SoC] or reverse) in the prophylaxis cohort. The prophylaxis treatment comprises 3 periods, 2 crossover pharmacokinetic (PK)/pharmacodynamic (PD) assessments (with a washout period of 14 [±2] days), and 1 end-of-study PK assessment (Figure). The enrollment approach is consistent for all age groups. Patients will have the option to receive at-home TAK-755 infusions. Patients in the on-demand cohort will be randomized to receive treatment with SoC or TAK-755. The primary outcome is the incidence of acute TTP episodes among patients receiving either TAK-755 or SoC prophylactically. Secondary outcomes include the proportion of acute events responding to TAK-755 without requiring the use of another ADAMTS13-replacing agent, time to resolution of clinical symptomatology, incidence of adverse events, and the effect of immunogenicity on the PK/PD profile of ADAMTS13.
Results: The study initiated in October 2017; the estimated completion date is January 2024.
Conclusions: This study will provide data on the safety and efficacy of TAK-755 as ADAMTS13 replacement therapy in patients with cTTP.
To cite this abstract in AMA style:Jain N, Marquez C, Martell L. Design of a Phase 3, Randomized, Controlled Study of Prophylactic and On-demand Treatment with Recombinant ADAMTS13 for Patients with Severe Congenital Thrombotic Thrombocytopenic Purpura [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/design-of-a-phase-3-randomized-controlled-study-of-prophylactic-and-on-demand-treatment-with-recombinant-adamts13-for-patients-with-severe-congenital-thrombotic-thrombocytopenic-purpura/. Accessed September 24, 2021.
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