WT1 Gene Overexpression in Differential Diagnosis of Ph-Negative Myeloproliferative Disorders

Abstract

Aim. To assess the rate of WT1 gene overexpression and its clinical value in Ph-negative myeloproliferative disorders (MPD). Materials & Methods. The trial included 72 patents with Ph-negative MPD. Among them there were patients with primary myelofibrosis (MF; n = 32), post-polycythemia vera MF (n = 7), polycythemia vera (PV; n = 17), and essential thrombocythemia (ET; n = 16) with median age of 57 years (range 19-78 years). Median (range) time from diagnosis to the date of evaluating WT1 expression in PV, ET, and MF was 9.4 (0-309), 14.4 (0-55), and 21.4 months (0-271 months), respectively. WT1 expression in terms of WT1 copies/10⁴ ABL copies was measured by quantitative PCR. Results. WT1 gene overexpression is revealed solely in patients with MF (in 34/39; 87 %). In PV/ET no WT1 gene overexpression was observed. Median WT1 expression in MF was 230/10⁴ ABL copies (range 42.2-9,316.45/10⁴ ABL copies). Sensitivity and specificity of WT1 gene overexpression in MF with respect to PV/ET were 87 % and 100 %, respectively. A distinct correlation was identified between WT1 gene expression level and spleen size, duration of the disease, blast cell count, and DIPSS risk group. WT1 gene expression level could be correlated neither with age and sex, nor with MF mutation status and leucocyte, thrombocyte, and haemoglobin levels. Conclusion It appears that due to a high specificity and sensitivity of WT1 gene expression in MF it can be used as a marker for differential diagnosis of Ph-negative MPD. A correlation between WT1 gene expression and tumor mass in MF cannot be excluded. It is advisable to analyze the dynamics of WT1 expression level to predict the efficacy of current targeted therapy.