Takeda Presents Late-Breaking Data from Phase 2b Study of Mezagitamab, Demonstrating Potential to Transform Treatment of Primary Immune Thrombocytopenia

Takeda (TSE:4502/NYSE:TAK) today presented positive results from its Phase 2b, 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), a rare immune-mediated bleeding disorder. ITP is characterized by the accelerated destruction of platelets in blood, resulting in a decreased platelet count and an increase of bleeding that can be debilitating. These data (Abstract #LB 01.1) were presented at the oral Late-Breakthrough Session at the 32^nd Congress of the International Society on Thrombosis and Haemostasis (ISTH) in Bangkok, Thailand. Takeda plans to initiate a global Phase 3 trial of mezagitamab in patients with ITP in the second half of FY2024.

The TAK-079-1004 trial (NCT04278924) evaluated three different doses of subcutaneous mezagitamab (100mg, 300mg and 600mg) versus placebo, given once weekly for eight weeks in patients with chronic or persistent primary ITP, followed by >8 weeks of safety follow-up. The primary endpoint is the percentage of patients with at least one Grade 3 or higher treatment emergent adverse events (TEAEs), serious adverse events (SAEs), and adverse events (AEs) leading to mezagitamab discontinuation.² Secondary endpoints included platelet response, complete platelet response, clinically meaningful platelet response, and hemostatic platelet response.^1,2

The Phase 2b trial results demonstrated that mezagitamab treatment improved platelet response compared to placebo, across all three dose levels of mezagitamab tested. Patients treated with mezagitamab showed rapid and sustained increases in platelet counts (above the 50,000/μL therapeutic threshold)⁴, that persisted eight weeks after the last dose through to Week 16, illustrating the rapid and post-therapy effects of mezagitamab on platelet response.¹

• All the different measures of platelet response evaluated were highest among patients treated with the mezagitamab 600mg dose, specifically 81.8% achieved complete platelet response, 90.9% clinically meaningful platelet response, and 100% hemostatic platelet response.¹
• Fewer mezagitamab-treated patients compared to placebo had ≥1 disease activity-related bleeding AE (17.9% vs 46.2%, respectively).¹

“Despite treatment with currently available therapies, there is still a significant disease burden and need for a disease modifying treatment that people living with ITP can tolerate,” said David Kuter, M.D., D.Phil., a leading expert in ITP and study presenter at the ISTH oral Late-Breakthrough Session. “These Phase 2b trial results are especially encouraging because they show mezagitamab’s favorable efficacy and safety profile – setting the stage for the generation of additional clinical evidence for this anti-CD38 monoclonal antibody with best-in-class potential for efficacy in ITP.”

In this study, mezagitamab had a favorable safety profile in patients with ITP, with no new safety signals and consistent with prior studies of mezagitamab.¹ The rates of TEAEs leading to discontinuation, Grade >3 TEAEs, and SAEs, between the mezagitamab dose groups combined versus placebo were 14.3% versus 0%, 17.9% versus 23.1%, and 14.3% versus 7.7% respectively.¹

“It is a privilege to have these Phase 2b mezagitamab results selected for presentation as a late-breaking abstract at the ISTH Congress,” said Obi Umeh, M.D., M.Sc., Vice President, Franchise Global Program Leader at Takeda. “Based on these results, we plan to initiate a Phase 3 study of mezagitamab in ITP in the second half of FY2024, further underscoring our goal to develop transformative treatments in therapeutic areas with high unmet patient needs.”

About Mezagitamab

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. Therapy with mezagitamab is designed to deliver rapid and sustained improvement in platelet response and to restore platelet counts to functional levels.

Mezagitamab previously received Orphan Drug Designation for the treatment of ITP and Fast Track Designation for treatment of chronic/persistent ITP from the U.S. Food and Drug Administration. Mezagitamab is an investigational compound that has not been approved for use by any regulatory authority.

About the Mezagitamab Phase 2b Trial in ITP

The data presented at the ISTH oral Late-Breakthrough Session are from a pre-specified interim analysis of the Phase 2b trial, a randomized, double-blind, placebo-controlled study evaluating the safety, tolerability, and efficacy of mezagitamab in patients with persistent or chronic primary ITP. The trial had two parts: 25 participants were randomized (1:1:1) to mezagitamab 100mg or 300mg, or placebo in Part A while 16 participants were randomized (2:1) to mezagitamab 600mg or placebo in Part B. Participants received once weekly subcutaneous mezagitamab or placebo for 8 doses, followed by ≥8 weeks of safety follow-up.¹

The primary endpoint is the percentage of patients with TEAEs including Grade 3 or higher events, SAEs and AEs leading to mezagitamab discontinuation. Secondary efficacy endpoints include and are defined as: platelet response (a platelet count ≥50,000/μL and ≥20,000/μL above baseline); complete platelet response (a platelet count ≥100,000/μL); clinically meaningful platelet response (a platelet count ≥20,000/μL above baseline); and hemostatic platelet response (participants with a baseline platelet count of <15,000/μL who achieve a platelet count of ≥30,000/μL and ≥20,000/μL above baseline).² For all secondary efficacy endpoints, platelet counts must be achieved on at least two visits without a dosing period-permitted rescue treatment in the previous four weeks and without any other previous rescue therapy.²

About ITP

ITP is a rare, IgG mediated autoimmune disease caused, in part, by the development of autoantibodies to platelets (and/or megakaryocytes), which are blood components responsible for preventing or stopping bleeding. It 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.^3,4

About Takeda

Takeda is focused on creating better health for people and a brighter future for the world. We aim to discover and deliver life-transforming treatments in our core therapeutic and business areas, including gastrointestinal and inflammation, rare diseases, plasma-derived therapies, oncology, neuroscience and vaccines. Together with our partners, we aim to improve the patient experience and advance a new frontier of treatment options through our dynamic and diverse pipeline. As a leading values-based, R&D-driven biopharmaceutical company headquartered in Japan, we are guided by our commitment to patients, our people and the planet. Our employees in approximately 80 countries and regions are driven by our purpose and are grounded in the values that have defined us for more than two centuries. For more information, visit www.takeda.com.

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References:

1. Kuter D, Pulanic D, et al. Safety, tolerability, and efficacy of mezagitamab (TAK-079) in chronic or persistent primary immune thrombocytopenia: Interim results from a phase 2, randomized, double-blind, placebo-controlled study. In: International Society on Thrombosis and Haemostasis (ISTH) Congress; June 22-26, 2024; Bangkok, Thailand. Abstract LB 01.1.
2. https://clinicaltrials.gov/study/NCT04278924. Accessed June 2024.
3. Provan D, Donald A, et al. Blood Advances. 2019;26;3(22):3780-3817.
4. Rodeghiero F. International Journal of Hematology. 2023;117:316–33.

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