Takeda Announces Positive Topline Results from Phase 2 Study Evaluating Mezagitamab (TAK-079), a Potential Best-in-Class Anti-CD38 Monoclonal Antibody, for Primary Immune Thrombocytopenia

Takeda (TSE:4502/NYSE:TAK) today announced positive topline results from a Phase 2, randomized, double-blind, placebo-controlled study evaluating the safety, tolerability and efficacy of mezagitamab (TAK-079) in patients with persistent or chronic primary immune thrombocytopenia (ITP). Mezagitamab is a fully human immunoglobulin IgG1 monoclonal antibody (mAb) with high affinity for CD38 expressing cells (including plasmablasts, plasma cells, natural killer cells) resulting in their depletion.

The TAK-079-1004 trial (NCT04278924) evaluated three different doses of subcutaneous mezagitamab vs placebo, given once weekly for eight weeks in patients with chronic (more than one year in duration) or persistent (3-12 months in duration) primary ITP. An interim analysis of the ongoing Phase 2 study demonstrated positive safety and efficacy results. Mezagitamab has been generally safe and well tolerated across all three cohorts. All mezagitamab doses tested demonstrated a higher platelet response rate than placebo. The increases in platelet count were dose-dependent with the greatest platelet response observed at the highest dose tested. Platelet response in mezagitamab treated patients occurred rapidly and was maintained post-therapy.

Based on these positive results, and following consultation with global health authorities, Takeda plans to initiate a global Phase 3 trial of mezagitamab in ITP in fiscal year 2024. When mezagitamab advances to Phase 3 in ITP Takeda will have five new molecular entities in Phase 3 development in fiscal year 2024 including TAK-279 for the treatment of psoriasis and psoriatic arthritis, TAK-861 for the treatment of narcolepsy type 1, soticlestat for the treatment of Lennox-Gastaut syndrome and Dravet syndrome, and fazirsiran for the treatment of α1-antitrypsin associated liver disease.

ITP is a rare, IgG mediated autoimmune disease caused, in part, by the development of autoantibodies to platelets (and/or megakaryocytes), which are blood cells responsible for preventing or stopping bleeding. ITP is characterized by the accelerated destruction of platelets (with or without impaired production), resulting in a decreased platelet count and an increased risk of bleeding, which can be debilitating (including fatigue and impaired quality of life), and in severe cases may be life-threatening. The precedent for approval of new drugs in this indication requires that platelet counts be maintained at 50,000/uL or more for a sustained period. Approximately 20 percent of patients with ITP do not achieve a platelet count above 50,000/uL following treatment with available first- and second-line therapies creating significant patient burden and unmet need for a disease modifying treatment that is also tolerable.^1,2