Kissei Launches TAVALISSE® Tab. 100mg and 150mg, an Oral Spleen Tyrosine Kinase Inhibitor, in Japan for Chronic ITP

Kissei Pharmaceutical Co., Ltd. (Head Office: Matsumoto, Nagano; Chairman and CEO: Mutsuo Kanzawa, "Kissei") today announced that TAVALISSE® Tab. 100mg and 150mg (generic name [JAN]: fostamatinib sodium hydrate, development code: R788), for chronic idiopathic thrombocytopenic purpura (ITP) launched on April 6, 2023, in Japan.

TAVALISSE® is an oral spleen tyrosine kinase (SYK) inhibitor discovered by Rigel Pharmaceuticals, Inc. (Head Office: USA, President and CEO: Raul Rodriguez; "Rigel"). It suppresses platelet destruction by macrophages thereby preventing platelet depletion and potentially improving the bleeding symptoms caused by chronic ITP. TAVALISSE® has a different mechanism of action than existing treatments. Therefore, it represents a new treatment option for adult patients with chronic ITP who have had an insufficient response to or were unable to tolerate conventional treatments such as steroids.

In October 2018, Kissei acquired the development and commercialization rights for this agent in Japan, China, South Korea and Taiwan from Rigel.

Kissei submitted a marketing authorization application in Japan for the indication of chronic ITP in April 2022, based on the successful results of Phase 3 clinical trials in patients in Japan and the United States, and received approval in December 2022. TAVALISSE® was listed on the NHI drug price list on March 15, 2023.

The product has been approved in the United States since 2018, under the brand name of TAVALISSE®(fostamatinib disodium hexahydrate) tablets and is indicated for the treatment of adult patients with chronic ITP who have had an insufficient response to a previous treatment. Product approvals have followed in Europe, Israel and Canada. It has been granted orphan drug designation in the United States, Japan and South Korea.

In order to use this drug appropriately, it is important to accumulate information on the patient's background under actual use, as well as information on safety and efficacy. Kissei will conduct all-case surveillance in all patients who are administered the agent until a pre-determined number of patients has been reached and promote the proper use of this drug with an approval condition imposed by the Ministry of Health, Labour and Welfare (MHLW).

Kissei has engaged in the research and development of new drugs focusing on rare diseases and diseases for which there are no sufficient treatments. We strive to contribute to treatments for patients suffering from serious illnesses.

The consolidated business forecast for fiscal year ending March 2024 including this matter will be disclosed at the Financial Results of fiscal year ending March 2023 to be held on May 8, 2023.

《 Reference 》

Product Summary of TAVALISSE®

Brand Name	TAVALISSE® Tab. 100mg,150mg
Generic Name	Fostamatinib sodium hydrate
Indications	Chronic idiopathic thrombocytopenic purpura
Dosage and Administration	The usual initial adult dose of fostamatinib is 100 mg taken orally twice daily. If platelet counts have not increased to the target level by 4 weeks after administrating the initial dose and there are no safety issues, the dose should be increased to 150 mg twice daily. The dosage may be adjusted according to the patient's platelet count and symptoms. The maximum dose is 150 mg twice daily.
Formulation	Film coated tablets
NHI price	TAVALISSE® Tab. 100mg 4,188.00 JPY TAVALISSE® Tab. 150mg 6,226.80 JPY
Manufactured and Distributed by	Kissei Pharmaceutical Co., Ltd.
Date of Marketing Approval in Japan	December 23, 2022
Date of Drug Price Listing	March 15, 2023
Date of Launch in Japan	April 6, 2023

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. In Japan, idiopathic thrombocytopenic purpura is listed as a designated intractable disease name and is used widely, while immune thrombocytopenia is the internationally accepted name for the disease.

The clinical symptoms of ITP include subcutaneous bleeding (petechiae or purpura) as well as bleeding from the gums or nose, and gastrointestinal, reproductive or urinary tracts, as well as 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 17,000* and 2.16 per 100,000** people are newly diagnosed with ITP every year in Japan. The cause of ITP has still not been definitively elucidated. It is believed that one of the possible causes of the decreased platelet count is 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.

*: The number of patients having certificates issued for specific disease treatment (designated intractable disease)
**: Int J Hematol, 2011, 93: 329-35

About Rigel Pharmaceuticals (Nasdaq: RIGL)
Rigel Pharmaceuticals, Inc., is a biotechnology company dedicated to discovering, developing and providing novel therapies that significantly improve the lives of patients with hematologic disorders and cancer. Founded in 1996, Rigel is based in South San Francisco, California, USA. For more details, please visit www.rigel.com