Abbisko Therapeutics Co., Ltd. ("Abbisko Therapeutics" hereafter) today announced that its CSF-1R inhibitor, pimicotinib (ABSK021), has been approved by the National Medical Products Administration ("NMPA") of the People's Republic of China for a phase II clinical study in patients with chronic graft-versus-host disease ("cGVHD"). Pre-clinical data indicated that pimicotinib is a highly potent and selective small molecule inhibitor of CSF-1R that may play important roles for treating many human diseases including complications associated with transplantations.

There is a huge unmet clinical need and commercial value for CSF-1R inhibitors against chronic graft-versus-host disease worldwide. It is understood that in September 2021, Syndax and Incyte agreed to jointly develop and commercialize Syndax's anti-CSF-1R monoclonal antibody axatilimab for treating chronic graft-versus-host disease and other fibrotic diseases. Under the agreement, Syndax can receive up to $117 million upfront, an equity investment of $35 million, and up to $450 million in potential milestone payments. Compared with antibody drugs, small molecule CSF-1R inhibition has possible safety, compliance, and production cost advantages.

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 is currently being investigated as a treatment for tenosynovial giant cell tumor (TGCT) and cGVHD, and under evaluation as treatment for a number of other indications.

In July 2022, pimicotinib was granted Breakthrough Therapy Designation from the Center for Drug Evaluation, NMPA for the treatment of TGCT that is not amenable to surgery. Subsequently in October 2022, Abbisko Therapeutics obtained CDE approval to conduct a Phase III clinical trial in TGCT for pimicotinib. Prior to these, pimicotinib demonstrated significant antitumor efficacy in a phase Ib trial in patients with TGCT, achieving a preliminary ORR of 68.0% and favorable safety profile.

Abbisko Therapeutics also completed a Phase Ia dose escalation study for ABSK021 in the U.S. and is conducting an ongoing Phase Ib multi-cohort expansion trial in both the U.S. and China. In addition to TGCT and cGVHD, Abbisko Therapeutics is actively exploring the potential of ABSK021 in treating many other types of solid tumors and has collaborated with Sperogenix (Shanghai) MedTech Co., Ltd. in exploring its potential for treating amyotrophic lateral sclerosis (ALS) among other central nervous system disorders. As of current, no highly selective CSF-1R inhibitor has been approved in China.

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