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April 27, 2022

Submission of New Drug Application for Fostamatinib, an oral spleen tyrosine kinase inhibitor, in Japan

Kissei Pharmaceutical Co., Ltd. (Head Office: Matsumoto, Nagano, Japan; Chairman and CEO: Mutsuo Kanzawa; "Kissei") announced that it has submitted a new drug application for approval of manufacturing and marketing in Japan for fostamatinib (generic name, development code: R788), an oral spleen tyrosine kinase (SYK) inhibitor, as indicated for chronic immune thrombocytopenic purpura (ITP).


Fostamatinib is an oral SYK inhibitor discovered by Rigel Pharmaceuticals, Inc. (Head Office: USA, President and CEO: Raul Rodriguez; "Rigel"). It suppresses platelet destruction by macrophages and platelet depletion, thereby potentially improving the bleeding symptoms caused by chronic ITP.


In October 2018, Kissei acquired the development and commercialization rights for fostamatinib in Japan, China, South Korea and Taiwan from Rigel. Kissei has submitted a new drug application for approval of manufacturing and marketing in Japan based on positive results from a Japan Phase III clinical trial in chronic ITP.


Fostamatinib was launched in the United States in 2018, under the brand name TAVALISSE®(fostamatinib disodium hexahydrate) tablets for the treatment of adult patients with chronic immune thrombocytopenia who have had an insufficient response to a previous treatment. Product launches have followed in Europe and Canada. It has been granted orphan drug status in the United States, Japan and South Korea.


Kissei is engaged in the research and development of new drugs with a focus on rare diseases and diseases for which there is no sufficient treatment. We strive to contribute to the treatment of patients suffering from illness.


The projected financial results for the fiscal year ending March 2023, which incorporates this progress, will be disclosed at the time of the announcement of the financial results currently scheduled on May 10, 2022.




《 Reference 》


About Idiopathic Thrombocytopenic Purpura (ITP)

ITP is a disease which causes serious bleeding events and bruising due to a decrease in platelet counts below 100,000/μL, despite the absence of other obvious illnesses and medications that cause thrombocytopenia. ITP is classified into "acute ITP" in which the platelet count recovers normally within 6 months from the onset and "chronic ITP" in which the thrombocytopenia continues for 6 months or more depending on the course of the medical condition. Fostamatinib is targeting for chronic ITP.


The clinical symptoms of ITP include subcutaneous bleeding (petechiae or purpura) as well as bleeding from the gums or nose, blood in the urine or stool, and intracranial bleeding.


ITP is designated as an "intractable disease" by the Minister of Health, Labour and Welfare. The number of patients with ITP is estimated to be approximately 19,000* and 2.16 per 100,000** people are newly diagnosed with ITP every year in Japan. While the cause of ITP has still not been definitively elucidated, it is believed that the platelet count is decreased as a result of the production of autoantibodies against platelets, leading to the destruction of opsonized platelets by macrophages in the spleen. ITP is currently treated with corticosteroids or thrombopoietin (TPO) receptor agonists as well as surgical removal of the spleen.


*: Estimated based on the number of patients having certificates issued for specific disease treatment (designated intractable disease)

**: Int J Hematol, 2011, 93: 329-35


About Fostamatinib (R788)

Fostamatinib is an oral spleen tyrosine kinase (SYK) inhibitor that suppresses platelet destruction by macrophages and platelet depletion. Thereby, improving the bleeding symptoms caused by immune thrombocytopenic purpura (ITP).


Fostamatinib has been granted orphan drug status in the United States, Japan and Korea. It was approved by the US Food and Drug Administration in April 2018 for the treatment of adult patients with chronic ITP and launched in May 2018 in the United States. Subsequently, fostamatinib has been launched in Canada and some European countries. Kissei entered into sublicense agreements in June 2021 and August 2021 for the rights to develop and commercialize fostamatinib in South Korea and China respectively, which are the Kissei territories.


About Rigel Pharmaceuticals (Rigel Pharmaceuticals, Inc.)

Rigel Pharmaceuticals, Inc., is a biotechnology company dedicated to discovering, developing and providing novel small molecule drugs that significantly improve the lives of patients with hematologic disorders, cancer and rare immune diseases. Rigel's pioneering research focuses on signaling pathways that are critical to disease mechanisms. Rigel is headquartered in South San Francisco, California, U.S.A. For more details, please visit www.rigel.com.