– SIAIS039 is an orally active PROTAC specifically targeting c-ros oncogene 1 (ROS1), demonstrating DC50 values of 154.46 nM, 126.47 nM, and 143.69 nM in HCC78 cells, Ba/F3 cells expressing CD74-ROS1 fusion, and Ba/F3 cells expressing SDC4-ROS1 fusion, respectively. This compound inhibits proliferation, induces cell cycle arrest, and triggers apoptosis in ROS1-positive cells, while also inhibiting colony formation. In vivo, SIAIS039 exhibits potent anti-tumoral activity against ROS1-driven tumor growth. The composition of SIAIS039 includes the ALK inhibitor Brigatinib, linker EM-12, and VHL E3 ubiquitin ligase ligand.