77.4% ORR! Abbisko to present the updated clinical phase Ib data of Pimicotinib (ABSK021) at the 2023 ASCO Annual Meeting

SHANGHAI,May 28,2023 -- Abbisko Therapeutics Co.,Ltd. ("Abbisko Therapeutics" hereafter) today announced that the updated results of Phase Ib study of its CSF-1R inhibitor Pimicotinib (ABSK021) in treating patients with advanced tenosynovial giant cell tumor ("TGCT"),will be released at the 2023 American Society of Clinical Oncology ("ASCO") annual meeting to be held in Chicago,USA from June 2 to June 6,2023.

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The data demonstrates the excellent antitumor efficacy and the safety profile of Pimicotinib in the treatment of patients with advanced TGCT and will be presented with the title of "EFFICACY AND SAFETY PROFILE OF PIMICOTINIB (ABSK021) IN TENOSYNOVIAL GIANT CELL TUMOR (TGCT): PHASE 1B UPDATE" in a poster presentation with the poster Bd# of "493".

Among the data released by Abbisko,the most remarkable result is the objective response rate (ORR) of the 50 mg QD dose group of Pimicotinib (ABSK021),which reached 77.4% (24/31),including two complete responses (CR) and 22 partial responses (PR). Additionally,87.5% (21/24) of patients with objective response were observed within the first 25 weeks.

In addition,Pimicotinib (ABSK021) also presented apparent advantages in terms of safety profile.

Currently Pexidartinib developed by Daiichi Sankyo is the only drug approved for the treatment of TGCT (tenosynovial giant cell tumor) in the global market. However,it has been given a "black box warning" by the FDA due to the potential risk of fatal liver damage,and its objective response (ORR) is only 38%. Nevertheless,Daiichi Sankyo achieved sales of approximately US$40 million in the global market with Pexidartinib. CICC predicts that the global market of TGCT could amount to around 1 billion US dollars. Compared with Pexidartinib of Daiichi Sankyo,Abbisko's Pimicotinib shows better efficacy and safety in the treatment of TGCT. Thus,it is expected to become a best-in-class drug. Assuming that Pimicotinib could be approved for the indication of TGCT in the United States in 2025 with a market penetration rate of 20%,its peak sales is expected to reach 3.14 billion yuan (after risk adjustment) with listing price reference to Pexidartinib of $250,000 per year.

About Pimicotinib

Pimicotinib is a novel,orally available,highly selective,and highly potent small molecule inhibitor of CSF-1R independently discovered and developed by Abbisko Therapeutics. A number of studies have shown that blocking the CSF-1R signaling pathway could effectively modulate and change macrophage functions,and potentially treat many macrophage-dependent human diseases. Pimicotinib has been granted the breakthrough therapy designation from both CDE on July 20,2022 and FDA on January 30,2023 for the treatment of tenosynovial giant cell tumor (TGCT) patients who are not amenable to surgery.

Pimicotinib is the first highly selective CSF-1R inhibitor discovered by a Chinese company that entered into a global phase III clinical trial. April 27,2023,the first patient dosing of "A Phase 3,Randomized,Double-blind,Placebo-Controlled,Multicenter Study of ABSK021 to Assess the Efficacy and Safety in Patients with Tenosynovial Giant Cell Tumor" was completed in Beijing Jishuitan Hospital. This study is the first global Phase III study of TGCT to be conducted simultaneously in China and the US. Approximately 100 participants are scheduled to be enrolled in approximately 50 centers worldwide,including 30 centers in China.

About TGCT

TGCT is a locally aggressive neoplasm which usually affects synovial joints,mucous sacs,and tendon membranes,resulting in swelling,pain,stiffness,and decreased activity of the affected joints which seriously affect the patient's quality of life. According to the 2013 World Health Organization classification,TGCTs were classified as localized TGCT and diffuse TGCT. Diffuse TGCT encompasses formerly known nodular tenosynovitis and pigmented villonodular synovitis (PVNS). Overexpression of CSF-1 occurs in most TGCTs. Surgical resection is the standard treatment for TGCT. However,not all patients are suitable for surgical treatment. It is difficult to remove tumors of diffuse TGCT patients by surgery,which may possibly lead to severe joint damage,total synovectomy,joint replacement,or even amputation,and the risk of surgical complications can be high. It has been reported that more than 50% of patients with diffuse TGCT will undergo recurrence after surgical resection. For TGCT patients not amenable to surgery,there is currently no approved drug available in China.