Zenyaku Kogyo Co., Ltd. (Japanese-only website) and Chugai Pharmaceutical Co., Ltd. (TOKYO: 4519) have announced that Zenyaku has received regulatory approval from the Ministry of Health, Labour and Welfare (MHLW) for the intravenous injection of Rituxan® (rituximab, genetic recombination) in both 100 mg and 500 mg dosages. This approval is specifically for the treatment of “refractory steroid-resistant nephrotic syndrome.”
Nephrotic syndrome refers to a condition characterized by significant damage to the glomerular slit membrane in the kidneys, resulting in severe proteinuria and hypoalbuminemia, which can lead to generalized edema. This syndrome is particularly prevalent in children, making it the most common chronic kidney disease among this age group and a designated intractable disease of unknown origin. Notably, about 10% to 20% of nephrotic syndrome cases are classified as “steroid-resistant,” meaning that standard steroid treatments do not lead to complete remission. In these cases, alternative therapies such as steroid pulse therapy or immunosuppressants are recommended. However, for patients with “refractory steroid-resistant nephrotic syndrome” who do not respond to these treatments, there is a heightened risk of developing end-stage renal failure, leading to a poor prognosis.
Rituxan is an anti-CD20 monoclonal antibody that specifically targets CD20, a protein present on B cells, while sparing hematopoietic stem cells and plasma cells. By engaging the body’s immune system, Rituxan attacks and damages these target B cells. Research suggests that B cells may play a role in the pathogenesis and disease activity of nephrotic syndrome, indicating that their removal through Rituxan treatment could yield therapeutic benefits.
Previously, Rituxan was approved in August 2014 for treating childhood-onset “refractory nephrotic syndrome” (frequently relapsing or steroid-dependent). In a recent investigator-initiated clinical trial focused on childhood-onset refractory steroid-resistant nephrotic syndrome, the primary endpoint—reduction in urinary protein creatinine ratio at 169 days—was successfully achieved. Following this, Zenyaku submitted an application for partial changes to the manufacturing and sales approval items on December 22, 2023, resulting in the current regulatory approval.
Both Zenyaku and Chugai are committed to collaborating closely to enhance the role of Rituxan in the treatment of refractory nephrotic syndrome.
