Rituxan Receives Japanese Approval for Autoimmune Hemolytic Anemia Treatment
Key Insights
Zenyaku Kogyo and Chugai Pharmaceutical announced that Rituxan (rituximab) received regulatory approval from Japan's MHLW for treating autoimmune hemolytic anemia (search) on February 19, 2026.
The approval follows a public knowledge-based application process initiated by Japanese hematology societies, with the application submitted in August 2025 after regulatory committee evaluations.
Autoimmune hemolytic anemia (search) is designated as an intractable disease in Japan, with approximately 80% of warm AIHA (search) patients showing improvement with steroids but facing common recurrence issues.
Zenyaku Kogyo Co., Ltd. and Chugai Pharmaceutical Co., Ltd. announced on February 19, 2026, that Zenyaku obtained regulatory approval from Japan's Ministry of Health, Labour and Welfare (MHLW) for an additional indication of Rituxan® (rituximab) for the treatment of autoimmune hemolytic anemia (search). The anti-CD20 (search) monoclonal antibody is available as intravenous injection formulations of 100 mg and 500 mg and is co-marketed by both companies.
Regulatory Pathway and Professional Society Support
The approval follows a comprehensive regulatory process initiated by professional medical societies. The Japanese Society of Hematology (search) and the Japanese Society of Pediatric Hematology/Oncology (search) submitted development requests for the additional indication. The request underwent evaluation at the 64th Evaluation Committee on unapproved or off-label drugs with high medical needs on July 4, 2025, where it qualified for a public knowledge-based application.
The Pharmaceutical Affairs Council's First Committee on Drugs officially approved the public knowledge-based application pathway on July 31, 2025. Zenyaku subsequently submitted the application on August 29, 2025, leading to the current approval.
Disease Background and Classification
Autoimmune hemolytic anemia (search) (AIHA) represents a collective term for immune hemolytic anemia caused by acquired autoantibodies that react with red blood cell membrane antigens, resulting in red blood cell destruction through antigen-antibody reactions and markedly shortened red blood cell lifespan. The condition is designated as an intractable disease by the Japanese government under designated intractable disease No. 61.
AIHA is broadly classified into two main categories: warm AIHA (search), where autoantibodies react near body temperature (37°C), and cold AIHA, which includes cold agglutinin disease (search) (CAD) and paroxysmal cold hemoglobinuria (search) (PCH) that react at temperatures below body temperature. Multiple factors including infection, immunodeficiency, immune system dysregulation, hormonal environment, drugs, and tumors are considered involved in AIHA etiology across all types.
Current Treatment Landscape and Unmet Needs
In warm AIHA (search) treatment, approximately 80% of patients show improvement with adrenocortical steroids (search); however, recurrence is common and long-term administration is necessary. For relapsed or refractory cases, splenectomy has been performed as a treatment option.
CAD patients face particular challenges, as maintaining warmth represents the most basic treatment approach, but severe symptoms including anemia, transfusion dependence, and peripheral circulatory disorders may occur. Japanese and international clinical practice guidelines recommend Rituxan therapy as one of the treatment options for such patients.
PCH represents a rare type mainly observed in young children following viral infections, generally treated with warmth maintenance and adrenocortical steroids (search). However, reports suggest Rituxan efficacy in chronic patients or those refractory to adrenocortical steroid therapy.
Mechanism of Action
Rituxan functions as an anti-CD20 (search) monoclonal antibody that specifically binds to CD20, a protein expressed on B cells, excluding hematopoietic stem cells and plasma cells. The drug attacks and damages target B cells by leveraging the human body's own immune system.
B cells ultimately differentiate into antibody-producing plasma cells, but in diseases involving autoantibodies, autoreactive B cells are believed to be activated and differentiated for unknown reasons, leading to plasma cell proliferation that produces autoantibodies. Although the etiology leading to autoreactive B cell activation and autoantibody appearance in AIHA has not been fully elucidated, the common presence of autoantibodies in both warm and cold AIHA suggests that therapeutic effects through B cell depletion by Rituxan can be expected.
Company Commitment
Zenyaku and Chugai have committed to working closely together to ensure that Rituxan can further contribute to the treatment of patients with autoimmune hemolytic anemia (search), expanding treatment options for this challenging intractable disease.