Crizotinib HCl is primarily used in the treatment of certain types of cancer, particularly non-small cell lung cancer (NSCLC) that is ALK-positive or ROS1-positive. It works by inhibiting the activity of specific proteins involved in the growth and spread of cancer cells. This targeted therapy helps slow down or stop the progression of the disease, often leading to improved outcomes for patients. It is typically administered orally and is often prescribed when other treatments have not been effective or are not suitable. Regular monitoring is required to manage potential side effects and assess the drug’s effectiveness.