ATRA is an anti-cancer (antineoplastic or cytotoxic) chemotherapy drug. ATRA is classified as a retinoid.Tretinoin is one of a group of drugs called retinoids that are similar to vitamin A. It is not a chemotherapy drug, but you may have it along with chemotherapy to treat a type of acute myeloid leukaemia called promyelocytic leukaemia. Tretinoin is also called all trans retinoic acid (ATRA) and its brand name is Vesanoid.