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A new class of drug for advanced chronic myeloid leukaemia
Sharan Prakash Sharma
The Lancet Oncology, In Press, Corrected Proof, Available online 28 March 2014
Patients with advanced chronic myeloid leukaemia (CML) might benefit from treatment with omacetaxine, according to a new study.
Different generations of tyrosine-kinase inhibitors (TKIs) represent the front lines of CML treatment. Patients with advanced-stage CML, in particular those with blast-phase (BP) or accelerated-phase (AP) disease, have infrequent or short duration of response with different generations of TKIs. Omacetaxine mepesuccinate acts by promoting apoptosis in leukaemic cells and is effective patients with CML who have TKI-resistant T315I mutations.
In this phase 2 study, researchers enrolled 99 heavily pretreated patients (51 with AP-CML and 44 with BP- CML) and assessed their response to subcutaneous omacetaxine. Omacetaxine mepesucciane induced major haematological response (the primary endpoint) in 19 (37%) patients with AP-CML and four (9%) of those with BP-CML. The response was noted irrespective of patients' mutational status. Major grade 3–4 side-effects were related to myelosuppression and were manageable. One case of treatment-related death was reported.
Some patients with both AP-CML and BC-CML had long-lasting stable disease while receiving omacetaxine, for up to 42·2 and 13·8 months, respectively. In reference to this result, Giuseppe Visani and Alessandro Isidori (Marche Nord Hospital, Pesaro, Italy) said “Even though results look dismal if compared to second generation TKIs, we have to keep in mind that the study population was made of extremely hard-to-treat patients, with 40% of them harbouring the T315I mutations.”
“Practically speaking, omacetaxine could be very helpful: first as bridge to transplant in younger patients; second as an ultimate [treatment] in advanced CML with no more weapons in its treatment armamentarium”, they added.
Emphasising the need for further study with different endpoints Clement Chung (Lyndon B Johnson General Hospital, Houston, TX, USA) explained that because of prior heavy treatment with other TKIs, overall survival is often confounded by treatment with other drugs, but omacetaxine has good endpoints even in heavily treated patients. “It warrants further study in combination therapy or in a different line of therapy in the treatment paradigm of CML patients”, he added.