Zenyaku's Rituxan Approved for Autoimmune Hemolytic Anemia Treatment

Approval and Application

Zenyaku Kogyo Co., Ltd. and Chugai Pharmaceutical Co., Ltd. announced the approval of Rituxan for treating autoimmune hemolytic anemia (AIHA) by Japan's Ministry of Health, Labour and Welfare. The approval followed a public knowledge-based application submitted on August 29, 2025, after evaluation by the Japanese Society of Hematology and the Japanese Society of Pediatric Hematology/Oncology.

Understanding AIHA

AIHA is characterized by the production of autoantibodies that attack red blood cells, leading to their destruction. It is classified into warm AIHA, where autoantibodies react at body temperature, and cold AIHA, including cold agglutinin disease (CAD) and paroxysmal cold hemoglobinuria (PCH), which react at lower temperatures. Factors such as infections, immune system dysregulation, and drugs contribute to AIHA's etiology.

Treatment Options

For warm AIHA, adrenocortical steroids are effective in about 80% of cases, but relapses are common, often necessitating long-term treatment or splenectomy. CAD treatment focuses on maintaining warmth, though severe symptoms may require additional interventions. Rituxan is recommended in clinical guidelines as a treatment option for AIHA, particularly in cases resistant to steroids.

Mechanism of Rituxan

Rituxan is an anti-CD20 monoclonal antibody that targets B cells, excluding hematopoietic stem cells and plasma cells. It works by depleting B cells, which are involved in the production of autoantibodies. This mechanism is beneficial in AIHA, where autoreactive B cells contribute to the disease's progression.