Omacetaxine for treatment-resistant or treatment-intolerant adult chronic myeloid leukemia

Abstract

The pharmacology, pharmacokinetics, clinical efficacy, and safety of a first-in-class protein synthesis inhibitor for use in treatment-resistant chronic myeloid leukemia (CML) are reviewed. Omacetaxine mepesuccinate (Synribo, Teva Pharmaceuticals) is a potent plant alkaloid isolated from Cephalotaxus (Chinese yew tree) species. It has a mechanism of action distinct from that of the standard first-line therapy for CML, tyrosine kinase inhibitors (TKIs), and has demonstrated efficacy in adult patients with chronic- or accelerated-phase CML who develop intolerance to two or more TKIs or experience multiple TKI treatment failures. Two open-label Phase II trials (combined n = 108) demonstrated that omacetaxine produced a major cytogenetic response in 18.4% of patients with chronic-phase CML and a major hematologic response in 14.3% of patients with accelerated-phase CML (median duration of reponse, 12.5 and 4.7 months, respectively). Symptom improvement or improved overall survival in omacetaxine-treated patients has not been demonstrated. In clinical trials to date, the most common grade 1-4 adverse reactions included thrombocytopenia, anemia, neutropenia, diarrhea, nausea, fatigue, and asthenia. The drug is administered subcutaneously on an intermittent schedule (14 days on, 14 days off during induction; 7 days on, 21 days off during maintenance). Research to better delineate omacetaxine's optimal role in the management of CML and other hematologic malignancies (e.g., acute myelogenic leukemia) is ongoing. Omacetaxine, a novel protein synthesis inhibitor, provides an alternative therapy for patients with CML who have experienced TKI treatment failures or are intolerant of two or more TKIs.