Belizatinib is primarily used in the treatment of non-small cell lung cancer (NSCLC), particularly in cases where the cancer has specific genetic mutations, such as ALK (anaplastic lymphoma kinase) rearrangements. It functions as a tyrosine kinase inhibitor, targeting and blocking the activity of ALK and other related kinases, which helps to slow down or stop the growth of cancer cells. This makes it a valuable option for patients who have developed resistance to other ALK inhibitors. Additionally, belizatinib is being studied for its potential efficacy in treating other types of cancers that are driven by similar genetic alterations, expanding its therapeutic applications.