Gleevec (imatinib mesylate), a highly promising new drug for the treatment of chronic myelogenous leukemia in blast crisis, in accelerated phase, and in chronic phase after interferon failure or intolerance, received orphan drug status from the U.S. Food and Drug Administration (FDA) Office of Orphan Products Development on January 31, 2001, and accelerated approval from the FDA for the above three indications on May 10, 2001.