According to the NCI website, omacetaxine mepesuccinate is a semisynthetic formulation of the cytotoxic plant alkaloid homoharringtonine isolated from the evergreen tree Cephalotaxus with potential antineoplastic activity. Indication gemäss EMEA:

Philadelphia chromosome positive chronic myeloid leukaemia in patients who have the T315I Bcr-Abl kinase domain mutation and who are resistant to prior imatinib therapy.

Link to Drug Information Portal, a service of the U.S. National Library of Medicine, National Institutes of Health
Link to MedlinePlus, a service of the U.S. National Library of Medicine, National Institutes of Health
Link to National Cancer Institute
Link zu Wiki

Link to Physicians Desk Reference (PDR)
Link to European Medicines Agency (EMEA)
Info for Patients presented by Scott Hamilton from Chemocare.com 

Zytostatikum