Abbisko Therapeutics Co. Ltd. announced dosing of the first patient in the phase I clinical trial dose expansion part in U.S for ABSK021, an oral small molecule CSF-1R inhibitor. The purpose of dose expansion is to access the safety, tolerability, and preliminary anti-tumor activity of ABSK021 in patients with multiple solid tumors. ABSK021 is a novel, orally available, highly selective, and highly potent small molecule inhibitor of CSF-1R. It has been previously shown by several clinical studies that blocking the CSF-1R signaling pathway could effectively modulate tumor microenvironment, relieve tumor immunosuppression, and synergize with other anti-cancer therapies such as immune checkpoint inhibitors to achieve tumor inhibition. Several clinical studies have also demonstrated that inhibition of CSF-1R activity could be used to treat tenosynovial giant cell tumor (TGCT), and to treat a variety of malignancies through combination with immuno-oncology and/or other therapeutic agents. As of the date of this article, no CSF-1R inhibitor has been approved in China. ABSK021 is the first selective CSF-1R inhibitor independently developed by a Chinese company that has advanced into human clinical trial. A phase Ia dose escalation study has been completed in the US and demonstrated excellent PK/PD and safety profile of ABSK021 in human. In parallel the comany have initiated ABSK021 phase I trial in China and have recruited several solid tumor patient including lung cancer patients.