Additional chromosome abnormalities in chronic myeloid leukemia

Abstract

The Philadelphia (Ph) chromosome and/or Breakpoint cluster region-Abelson leukemia virus oncogene transcript are unique markers for chronic myeloid leukemia (CML). However, CML demonstrates heterogeneous presentations and outcomes. We analyzed the cytogenetic and molecular results of CML patients to evaluate their correlation with clinical presentations and outcome. A total of 84 newly diagnosed CML patients were enrolled in the study. Patients were treated according to disease status. Bone marrow samples were obtained to perform cytogenetic and molecular studies. Clinical presentations, treatment courses, and survival were reviewed retrospectively. Among 84 patients, 72 had chronic phase and 12 had accelerated phase CML. Cytogenetic study showed 69 (82.1%) with the classic Ph chromosome, 6 (7.2%) with a variant Ph chromosome, and 9 (10.7%) with additional chromosome abnormalities. Fifty-four (64.3%) cases harbored b3a2 transcripts, 29 (34.5%) had b2a2 transcript, and 1 had e19a2 transcript. There was no difference in clinical presentations between different cytogenetic and molecular groups; however, additional chromosome abnormalities were significantly associated with the accelerated phase. Imatinib therapy was an effective treatment, as measured by cytogenetic response, when administered as first- and second-line therapy in chronic phase patients. Survival analysis showed that old age, additional chromosome abnormalities, high Sokal score, and no cytogenetic response in second-line therapy had a significant poor impact (p<0.05). In conclusion, we presented the cytogenetic and molecular pattern of CML patients and demonstrated that the additional chromosome abnormality was associated with poor outcome.

Keywords

• Additional chromosome abnormality
• BCR-ABL
• Chronic myeloid leukemia
• Variant Philadelphia chromosome