Imatinib, sold under the brand names Gleevec and Glivec (both marketed worldwide by Novartis) among others, is an oral targeted therapy medication used to treat cancer. Imatinib is a small molecule inhibitor targeting multiple tyrosine kinases such as CSF1R, ABL, c-KIT, FLT3, and PDGFR-β. Specifically, it is used for chronic myelogenous leukemia (CML) and acute lymphocytic leukemia (ALL) that are Philadelphia chromosome–positive (Ph+), certain types of gastrointestinal stromal tumors (GIST), hypereosinophilic syndrome (HES), chronic eosinophilic leukemia (CEL), systemic mastocytosis, and myelodysplastic syndrome. Common side effects include vomiting, diarrhea, muscle pain, headache, and rash. Severe side effects may include fluid retention, gastrointestinal bleeding, bone marrow suppression, liver problems, and heart failure. Use during pregnancy may result in harm to the baby. Imatinib works by stopping the Bcr-Abl tyrosine-kinase. This can slow growth or result in programmed cell death of certain types of cancer cells. Imatinib was approved for medical use in the United States in 2001. It is on the World Health Organization's List of Essential Medicines. A generic version became available in the UK as of 2017. Source: Wikipedia (en)