Clinical Outcomes of Patients With Chronic Myeloid Leukemia With Concurrent Core Binding Factor Rearrangement and Philadelphia Chromosome

Background: Acquisition of additional cytogenetic abnormalities (ACAs) in addition to Philadelphia chromosome is frequently observed in patients with chronic myeloid leukemia (CML) in advanced phase. The presence of core binding factor (CBF) translocations determines the diagnosis of acute myeloid leukemia regardless of blast percentage, and CBF rearrangements are rarely identified as ACAs. Patients and Methods: A retrospective chart review of patients with CML who had CBF rearrangement, t(8;21) or inv(16), in Philadelphia chromosome-positive clones was conducted. Additional cases of CML with CBF rearrangements were identified through literature review. Results: Between August 1997 and December 2014, we identified 11 patients who had Philadelphia chromosome and CBF rearrangement in the same clones: 1 (9%) with t(8;21) and 10 (91%) with inv(16). Nine (82%) patients were in blast phase, and 2 (18%) in second chronic phase. Four (36%) patients received tyrosine kinase inhibitor monotherapy, 2 (18%) received tyrosine kinase inhibitor and chemotherapy, and 5 (45%) received chemotherapy only. Three (27%) patients achieved complete remission with incomplete count recovery, and 4 (36%) had no response after the initial therapy. Three (27%) patients underwent allogeneic stem cell transplantation. The median event-free survival and overall survival for the 11 patients were 2 months and 6 months, respectively. Literature review identified 14 patients with CML with CBF rearrangement with a median overall survival of 14 months. Conclusion: Acquisition of CBF rearrangement in addition to Philadelphia chromosome is a rare phenomenon associated with poor prognosis. CBF rearrangements as ACAs in patients with CML can be considered high-risk features.