Results from a phase 2 clinical trial designed and overseen by researchers at Massachusetts General Brigham Cancer Institute showed that the investigational drug mezagitamab may effectively increase platelet counts in patients with immune thrombocytopenia (ITP). ITP is an autoimmune disease characterized by increased platelet destruction and decreased platelet production, increasing bleeding risk and impairing quality of life.
The result is New England Medical Journalis particularly relevant given that approximately 20% of ITP patients do not benefit from current treatments.
“This is a novel treatment that is fast-acting and attacks the underlying mechanisms of the disease,” said lead author David J. Cooter, MD, a hematologist at the Massachusetts General Brigham Cancer Institute. “We found that this had a rapid effect, normalizing platelet counts within 48 hours and improving quality of life.”
Mezagitamab is an antibody originally developed as a potential treatment for cancer that targets the CD38 protein expressed on the surface of a variety of immune cells, particularly plasma cells, natural killer cells, and certain T and B cells. Anti-CD38 therapy inhibits these immune cells and has shown its effectiveness against autoimmune diseases.
In a phase 2 clinical trial sponsored by Takeda Development Center Americas, researchers tested mezagitamab’s potential for ITP. Researchers enrolled adults from Bulgaria, China, Croatia, Greece, Italy, Japan, Slovenia, Spain, and Ukraine with ITP that had lasted at least three months. In this study, 41 participants were randomly assigned to receive 100 mg of mezagitamab, 300 mg of mezagitamab, or a placebo subcutaneously. Following encouraging results from a safety analysis conducted after the trial began, participants were assigned in a 2:1 ratio to receive 600 mg of mezagitamab or to receive a placebo.
Treatment with mezagitamab resulted in increased platelet counts and had a safety profile similar to placebo. Through week 16, platelet responses were observed in 10 of 11 (91%) patients in the mezagitamab 600 mg group compared with 3 of 13 (23%) in the placebo group.
“This study was designed as a dose-ranging, proof-of-concept study. We are currently conducting a Phase 3 clinical trial of mezagitamab at the 600 mg dose at Massachusetts General Brigham Cancer Institute as our lead North American site,” Cooter said.
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Reference magazines:
Cooter, D.J. Others. (2026). A phase 2 randomized trial of mezagitamab in primary immune thrombocytopenia. New England Medical Journal. DOI: 10.1056/nejmoa2513120. https://www.nejm.org/doi/full/10.1056/NEJMoa2513120
