PIMJETMI® (pimicotinib) Developed by Abbisko Therapeutics and Licensed by Merck KGaA, Darmstadt, Germany Receive U.S. FDA Approval for TGCT

• PIMJETMI^® (pimicotinib) is a new systemic treatment option for certain U.S. adult patients with symptomatic tenosynovial giant cell tumor (TGCT), demonstrating durable^* tumor response with clinically meaningful improvements in certain clinical outcome assessments, including physical function and pain
• Abbisko to receive milestone payment upon the first commercial sale in the U.S. in addition to double-digit royalties on net sales
• U.S. FDA approval marks the fourth marketing approval for PIMJETMI^® following China NMPA, Health Canada and Swissmedic, accelerating worldwide commercialization

SHANGHAI, Nov. 10, 2026 — Abbisko Therapeutics Co., Ltd. ("Abbisko Therapeutics" hereafter, HKEX code: 02256.HK) today announced that the U.S. Food and Drug Administration (FDA) has approved PIMJETMI^® (pimicotinib), a small-molecule colony-stimulating factor 1 receptor (CSF-1R) inhibitor, as a systemic treatment for adults with symptomatic tenosynovial giant cell tumor (TGCT) for which surgical resection may cause worsening functional limitation or severe morbidity.

Yao-Chang Xu, PhD, Founder and Chief Executive Officer of Abbisko Therapeutics, highlights, "The U.S. FDA approval of PIMJETMI^® marks a significant milestone in Abbisko Therapeutics' innovation and global development journey. As our first proprietary innovative medicine to reach commercialization, PIMJETMI^® is now approved in China, Canada, Switzerland and the United States, and our global commercialization partnership with Merck KGaA, Darmstadt, Germany is accelerating its availability to more patients worldwide. This achievement demonstrates Abbisko's end-to-end capabilities spanning early-stage drug discovery, global clinical development, and regulatory submission. We will continue to remain science-driven and patient-centered, focusing on unmet medical needs worldwide and advancing differentiated innovative medicines to bring more clinically meaningful treatment options to patients globally."

"People living with TGCT have long faced difficult treatment decisions as they navigate a disease that can significantly affect their daily lives including their mobility," said Danny Bar-Zohar, CEO Healthcare and Member of the Executive Board of Merck KGaA, Darmstadt, Germany. "Translating scientific innovation into clinically meaningful advances for people living with rare tumors is a strategic imperative for our company, as we continue our commitment to addressing significant unmet needs. With the approval of PIMJETMI^® in the U.S., we strengthen our leadership position and growing portfolio in rare tumors and bring real hope to patients and their families."

PIMJETMI^® is an orally available and potent small-molecule CSF-1R inhibitor independently developed by Abbisko Therapeutics, with global commercialization rights granted to Merck KGaA, Darmstadt, Germany. The U.S. FDA approval marks the fourth NDA approval for PIMJETMI^®, following approvals in China by the National Medical Products Administration (NMPA) in December 2025, in Canada by Health Canada in June 2026, and in Switzerland by the Swiss Agency for Therapeutic Products (Swissmedic) in October 2026, further accelerating the global commercialization plan. Upon the first commercial sale in the United States, Abbisko will receive an additional milestone payment. Abbisko is also eligible to receive double-digit royalties on global net sales of PIMJETMI^®, as well as potential payments relating to other regulatory, development, and commercial sales milestones.

TGCT is a rare, locally aggressive tumor that primarily affects the joints, tendon sheaths, and bursae. It can cause pain, swelling, stiffness, and limited joint mobility, significantly affecting patients' daily activities and quality of life. TGCT is driven by overexpression of colony-stimulating factor-1 (CSF-1) in neoplastic synovial cells which leads to accumulation of CSF-1R expressing inflammatory cells in the tumor.

The FDA approval of PIMJETMI^® is based on primary and longer-term results from the global Phase III MANEUVER study and the Open-Label Extension. PIMJETMI^® demonstrated a statistically significant improvement in objective response rate (ORR) at week 25 as assessed by blinded independent review committee (BIRC) based on RECIST v1.1 compared with placebo (56% vs. 3% for placebo; p<0.0001). PIMJETMI^® also demonstrated clinically meaningful and statistically significant improvements as compared to placebo across secondary endpoints relevant to patients' daily lives, improving relative range of motion (p=0.0003), physical functioning (p=0.0074), and pain (p<0.0001). Results from the MANEUVER study were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting. In longer-term follow-up (median 14.3 months for patients initially randomized to pimicotinib), presented at the European Society for Medical Oncology (ESMO) Congress in 2025, the median duration of response was not reached. The majority of patients (77%) with response at week 25 maintained clinical benefit after an additional 12 months of follow-up, demonstrating the durability  of response with PIMJETMI^®.

The applications for PIMJETMI^® in the United States, Canada and Switzerland were reviewed under Project Orbis, an international collaboration framework initiated by the FDA Oncology Center of Excellence to facilitate collaboration among participating regulatory authorities and accelerate the review of oncology products. Project Orbis currently brings together regulatory authorities from multiple countries and regions, providing an important platform for international regulatory collaboration and the coordinated global development of innovative medicines.

^* The majority (77%) of patients with response at 25 weeks maintained this clinical benefit after an additional 12 months of treatment.

SOURCE Abbisko Therapeutics Co., Ltd.