Imatinib Imatinib (originally STI571) is a drug used to treat certain types of cancer. Imatinib mesilate (INN) is used in treating chronic myelogenous leukemia (CML), gastrointestinal stromal tumors (GISTs) and some other diseases. By 2011, Gleevec has been FDA approved to treat ten different cancers. NATCO an Indian drug company also makes a generic version of Gleevec called Veenat. In India generic Gleevec is available also available under the name of "Imatib". It is manufacturing & marketing by CIPLA drug company.