Imatinib 400 mg Tablets The Imatinib 400 mg Tablet is a drug that saves lives and is commonly prescribed for the treatment of different types of cancers like Chronic Myeloid Leukemia (CML) and Gastrointestinal Stromal Tumors (GISTs). It is a tyrosine kinase inhibitor that works by preventing the signaling of cancer cells through the abnormal proteins, hence stopping the growth and the invasion of the cancer cells in the body. The medication has secured its status as a primary