Philadelphia chromosome-positive mixed phenotype acute leukemia in the imatinib era.

Although the introduction of imatinib dramatically improved the outcomes for patients with Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia ( Ph+ BCP- ALL), the survival benefit of imatinib has not been assessed in the context of Ph+ mixed phenotype acute leukemia ( Ph+ MPAL). To clarify this important issue, we studied 42 Ph+ acute leukemia ( Ph+ AL) patients who received intensive chemotherapy and concurrent administration of imatinib. Of the 42 Ph+ AL patients, 13 (31%) patients were categorized as Ph+ MPAL (positive for both myeloid and B-cell lineage), 27 (64%) were categorized as Ph+ BCP- ALL, and two (5%) were categorized as Ph+ acute myeloid leukemia. The complete remission rates after the initial induction therapy were not significantly different when comparing Ph+ MPAL and Ph+ BCP- ALL patients (100% vs. 85%, respectively, P = 0.14). Likewise, there were no significant differences in the 5-yr overall survival ( OS) or disease-free survival ( DFS) rates when comparing the MPAL and BCP- ALL groups ( OS: 55% vs. 53%, respectively, P = 0.87, DFS: 46% vs. 42%, respectively, P = 0.94). These findings suggest that concurrent imatinib administration with chemotherapy improved the outcomes of Ph+ MPAL patients to the level seen in Ph+ BCP- ALL patients and should, therefore, be considered as the standard therapy for these patients. [ABSTRACT FROM AUTHOR]