Marketing Authorization for the Oral Spleen Tyrosine Kinase Inhibitor TAVALISSE® in South Korea

Kissei Pharmaceutical Co., Ltd. (Head Office: Matsumoto, Nagano, Japan; Chairman and CEO: Mutsuo Kanzawa; "Kissei") announced that its licensing partner, JW Pharmaceutical Corporation (Head Office: The Republic of Korea, CEO: YS Shin; "JWP"), has obtained marketing authorization from the Ministry of Food and Drug Safety (MFDS) for the oral spleen tyrosine kinase (SYK) inhibitor Tavalisse® (fostamatinib disodium hexahydrate) for the treatment of thrombocytopenia in adult patients with chronic idiopathic thrombocytopenic purpura (ITP) who have had an insufficient response to a previous treatment.

Tavalisse 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 improving the bleeding symptoms caused by ITP.

In October 2018, Kissei acquired the development and commercialization rights for fostamatinib in Japan, China, South Korea, and Taiwan from Rigel.¹ In June 2021, Kissei granted JWP the development and commercialization rights for South Korea.² 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, Canada, and the Middle East. The product has also been granted orphan drug designation in the United States, Japan and South Korea. In Japan, Kissei launched Tavalisse in April 2023.³

As a result of obtaining marketing authorization, it is expected that a new treatment option will be provided to chronic ITP patients in Korea.

The projected financial results for the fiscal year ending March 2025, which incorporate this progress, were disclosed during the announcement of the financial results on November 5, 2024.


1 News Release: October 30, 2018
Announcement of in-licensing of technology related to a small molecule tyrosine kinase inhibitor fostamatinib

2 News Release: June 28, 2021
Sub-licensing Agreement for Spleen Tyrosine Kinase Inhibitor "Fostamatinib (R788)" with JW Pharmaceutical Corporation

3 News Release: April 6, 2023
Kissei Launches TAVALISSE® Tab. 100mg and 150mg, an Oral Spleen Tyrosine Kinase Inhibitor, in Japan for Chronic ITP


《Reference》

About Idiopathic Thrombocytopenic Purpura (ITP)

ITP is a disease that causes serious bleeding events and bruising due to a decrease in platelet count 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 thrombocytopenia continues for 6 months or more depending on the course of the medical condition. Fostamatinib is a treatment 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 17,000* 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 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 JW Pharmaceutical Corporation
JW Pharmaceutical Corporation is Korea's leading pharmaceutical company, founded in 1945. They lead innovation by engaging in the development of innovative new medicines and working to improve people's health and lives with cross-boundary efforts.

JW Pharmaceutical Corporation and Kissei have concluded contracts for Silodosin, a drug for the improvement of urinary dysfunction, and Mitiglinide, a drug for the treatment of diabetes mellitus, both created by Kissei. These drugs are still utilized for the treatment of patients in Korea.

Additionally, we have signed an out-licensing agreement for our GnRH antagonist "Linzagolix," which JW Pharmaceutical Corporation is currently developing in South Korea. For more details, please visit https://www.jw-pharma.co.kr/pharma/en/main.jsp.

About Rigel Pharmaceuticals (Rigel Pharmaceuticals, Inc.)

Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) 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. For more information on Rigel, the Company's marketed products and pipeline of potential products, visit https://www.rigel.com/.