Clonal chromosomal abnormalities appearing in Philadelphia chromosome–negative metaphases during CML treatment

Clonal chromosomal abnormalities in Philadelphia chromosome-negative (CCA/Ph−) metaphases emerge as patients with chronic phase chronic myeloid leukemia (CP-CML) are treated with tyrosine kinase inhibitors (TKIs). We assessed the characteristics and prognostic impact of 598 patients with CP-CML treated on clinical trials with various TKIs. CCA/Ph− occurred in 58 patients (10%); the most common were −Y in 25 (43%) and trisomy 8 in 7 patients (12%). Response to TKI therapy was similar for patients with CCA/Ph− and those without additional chromosomal abnormalities (ACAs). We further categorized CCA/Ph− into those in which –Y was the only clonal abnormality, and all others. We found that patients with non –Y CCA/Ph− had worse failure-free survival (FFS), event-free survival (EFS), transformation-free survival (TFS), and overall survival (OS) compared with those without ACAs with the following 5-year rates: FFS (52% vs 70%, P = .02), EFS (68% vs 86%, P = .02), TFS (76% vs 94%, P < .01), and OS (79% vs 94%, P = .03). In a multivariate analysis, non –Y CCA/Ph− increased the risk of transformation or death when baseline characteristics were considered with a hazard ratio of 2.81 (95% confidence interval, 1.15-6.89; P = .02). However, this prognostic impact was not statistically significant when achieving BCR-ABL