(S)-Crizotinib is a selective inhibitor of anaplastic lymphoma kinase (ALK) and ROS1 tyrosine kinases, primarily utilized in pharmaceutical research and development for targeting ALK-positive or ROS1-positive non-small cell lung cancer (NSCLC) and other oncogene-driven malignancies. It functions by binding to and inhibiting the kinase activity of ALK and ROS1 fusion proteins, thereby disrupting downstream signaling pathways that promote cancer cell proliferation and survival. This compound is supplied as a high-purity reagent (≥99%) for laboratory use in drug discovery, synthesis, and biological studies. It is not intended for direct clinical administration or human consumption; professional handling and safety protocols are required.