Zenyaku Kogyo Co., Ltd., in collaboration with Chugai Pharmaceutical Co., Ltd., has secured approval from the Japanese Ministry of Health, Labour and Welfare (MHLW) for Rituxan (rituximab) intravenous injection for the treatment of chronic idiopathic thrombocytopenic purpura (ITP) in children. This approval expands the use of Rituxan, an anti-CD20 monoclonal antibody, to address an unmet need in pediatric patients with chronic ITP.
The approval was based on a public knowledge-based application following a request from the Japanese Society of Paediatric Haematology/Oncology. The application was prompted by the lack of approved treatments for chronic ITP in children and was evaluated at the “58th evaluation committee on unapproved or off-labeled drugs with high medical needs” held on March 22, 2024.
Understanding ITP
ITP is an autoimmune disorder characterized by the expression of autoantibodies against platelet membrane proteins, leading to thrombocytopenia due to platelet destruction and impaired production. It is designated as an intractable disease in Japan. While many newly diagnosed pediatric ITP patients exhibit severe thrombocytopenia, serious bleeding events like intracranial hemorrhage are rare, and the condition often resolves spontaneously. However, an estimated 30-56% of cases require treatment, and some prove resistant to primary treatments such as corticosteroids or intravenous immunoglobulin therapy.
Rituxan's Mechanism of Action
Rituxan is an anti-CD20 monoclonal antibody that specifically targets CD20, a protein expressed on B cells (excluding hematopoietic stem cells and plasma cells). By binding to CD20, Rituxan triggers the body's immune system to attack and eliminate these target B cells. The involvement of B cells in the pathogenesis of ITP has been suggested, and their elimination with Rituxan is expected to provide therapeutic benefits for chronic ITP resistant to first-line treatments. Both domestic and international clinical guidelines recommend Rituxan as one of the treatment options for such paediatric ITP patients.
Clinical Implications
This approval provides a valuable treatment option for pediatric patients with chronic ITP who have not responded to initial therapies. Zenyaku and Chugai aim to continue their collaboration to ensure that Rituxan can further contribute to the treatment of chronic ITP in both adults and children.
