Does HOXA9 Gene Expression in Egyptian Chronic Myelogenous Leukemia Patients Affect Disease Progression? A Retrospective Cohort Study

Objective: Chronic myelogenous leukemia (CML) is a clonal stem cell disease and is consistently associated with the BCR-ABL fusion gene. The chronic phase of the disease tends to pass into an accelerated phase and eventually leads to acute leukemia if left untreated. Oncoproteins necessary for leukemic transformation are both fundamentally and clinically relevant to identify as they might be new molecular targets for the development of specific anti-leukemic drugs. This study is an initial step to define the proportion of HOXA9 gene expression in some Egyptians with chronic-phase CML at diagnosis and to evaluate its relation with BCR-ABL expression and its clinical significance. Materials and Methods: Sixty-two newly diagnosed CML patients (56 in chronic phase, 1 in accelerated phase, and 5 in blastic crises) were enrolled in the study. HOXA9 and BCR-ABL gene expressions were detected by one-step RT-PCR. ABL was chosen as a control gene to calculate HOXA9/ABL and BCR-ABL/ABL ratios from densitometric values of PCR product intensities. Results: HOXA9 expression was encountered in 25/56 (44.6%) of newly diagnosed CML patients in the chronic phase. The median expression was 0.31 (range: 0.08-1.37) in relation to the ABL gene, with a higher frequency of expression in CML patients presenting with splenomegaly (p<0.001), high Sokal score (p<0.001), and BCR-ABL expression from the first round (p=0.004). No association could be detected with other clinical parameters, overall survival, or disease-free survival. Conclusion: HOXA9 expression is closely related to poor prognostic factors, but We could not demonstrate its relationship to patient survival.