Homoharringtonine for the treatment of chronic myelogenous leukemia

Background: The anticancer activity of the natural alkaloid homoharringtonine (HHT) was first recognized by Chinese investigators. HHT exerts its activity through inhibition of protein synthesis and promotion of apoptosis. Methods: The authors reviewed the most relevant preclinical and clinical studies involving patients with chronic myelogenous leukemia (CML) receiving therapy with either natural HHT or omacetaxine mepesuccinate (Ceflatonin, Myelostat, CGX-653), a semisynthetic subcutaneously bioavailable form of HHT presently under development for the treatment of CML. Results: Prior to the advent of the tyrosine kinase inhibitor (TKI) imatinib mesilate, controlled clinical studies established HHT as the most active therapy in CML after failure of IFN-a for patients who were not candidates for allogeneic stem cell transplantation. Preliminary results from Phase II Studies suggest that omacetaxine mepesuccinate is active in patients with imatinib-resistant CML, including those carrying the T315I mutation, which renders imatinib and second-generation TKIs ineffective. Conclusion: These encouraging results have propelled the development of several Phase II/III trials both in Europe and in the US to further delineate the activity of omacetaxine mepesuccinate in patients with CML who are resistant to TKI therapy.