Mezagitamab Improves Platelet Counts in Chronic ITP in Phase 2 Trial
USA: A Phase 2 trial has revealed that treatment with mezagitamab increased platelet counts in patients with persistent or chronic immune thrombocytopenia (ITP), with a safety profile comparable to placebo.
A study published in the New England Journal of Medicine (NEJM) highlights the potential of mezagitamab, a novel anti-CD38 monoclonal antibody, as a therapeutic option for patients with difficult-to-treat ITP. This autoimmune condition is characterized by accelerated platelet destruction and impaired platelet production, leading to an elevated risk of bleeding and reduced quality of life. Notably, a significant proportion of patients do not achieve adequate responses with currently available treatments.
Led by David J. Kuter and colleagues, the multicenter, double-blind, randomized, placebo-controlled trial evaluated the safety and efficacy of mezagitamab administered subcutaneously once weekly for eight weeks. Adults with persistent or chronic ITP and a mean platelet count below 30,000 per microliter were enrolled. Participants were randomized to receive mezagitamab at doses of 100 mg, 300 mg, or 600 mg or a placebo.
The primary endpoint focused on safety, while a key secondary endpoint assessed platelet response. A response was defined as achieving a platelet count of at least 50,000 per microliter with an increase of at least 20,000 per microliter from baseline on at least two occasions within 16 weeks.
The study included 28 participants in the mezagitamab group and 13 in the placebo group. Patients had a history of multiple prior therapies, reflecting a population with treatment-resistant disease. Baseline platelet counts were low across both groups, highlighting the severity of the condition.
Key Findings:
- Safety outcomes were comparable between the mezagitamab and placebo groups.
- Adverse events were reported in approximately two-thirds of participants in both groups.
- Rates of severe (grade ≥3) and serious adverse events were similar, indicating no additional safety risk with mezagitamab.
- Mezagitamab significantly improved platelet counts, with the greatest effect seen at higher doses.
- In the 600 mg group, 91% of participants achieved a platelet response compared to 23% in the placebo group.
- The findings demonstrate a clear dose-dependent response.
- Targeting CD38-expressing cells appears to be a promising approach for improving platelet levels in ITP patients.
Overall, the trial provides encouraging evidence that mezagitamab may offer a new treatment avenue for patients with persistent or chronic ITP, especially those who have not responded to existing therapies. While the results are promising, larger trials will be necessary to confirm these findings and to better define the long-term safety and durability of response.
“Treatment with mezagitamab improved platelet counts while demonstrating a safety profile comparable to placebo in patients with persistent or chronic immune thrombocytopenia,” the authors concluded.
Reference:
DOI: 10.1056/NEJMoa2513120
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