Prognostic Significance of WT1 Gene Expression in Patients with Acute Leukemia

Huh, Hee Jin; Park, Chan Jeoung; Seo, Eul Ju; Chi, Hyun Sook; Lee, Je Hwan; Lee, Kyoo Hyung; Seo, Jong Jin; Moon, Hyung Nam; Ghim, Thad

Abstract

BACKGROUND
The Wilms' tumor gene (WT1) is located on chromosome 11p13. Several authors have shown that the expression of WT1 gene is associated with prognosis of acute leukemia. It was the aim of this study to investigate the relationship between WT1 positivity and the response to treatment in terms of rate of complete remissions (CR), and survival and to evaluate the prognostic value of WT1 expression in patients with acute leukemia. METHODS: We examined the presence of WT1 specific mRNA in bone marrow samples of 71 patients with acute leukemia at diagnosis (AML 39, ALL 32) by nested RT-PCR. The integrity and the amount of RNA were analyzed by amplification of the -actin gene as an internal control. The relative ratio of WT1 gene expression/ -actin was calculated and classified as not amplified (0), weakly amplified (1+), moderately amplified (2+), or strongly amplified (3+). RESULTS: Thirty-four (47.9%) of the patients with acute leukemia at diagnosis were WT1 PCR positive. Among the WT1 positive patients, 10 patients (14.1%) showed 1+, 20 patients (28.2%) 2+, and 4 patients (5.6%) 3+. The patients with WT1 mRNA expression were younger than those without it in AML. There was a tendency of a higher CR rates in WT1 negative patients than in WT1 positive ones (AML 61.9% vs. 50%, ALL 75.0% vs. 68.8%). The probability of 5 year survival was 62.2% for WT1 negative group and 44.1% for WT1 positive group in all patients. The median survival days accord-ing to levels of WT1 expression was 709 days for negative group, 310 days for 1+ or 2+ groups and 294 days for 3+ group. CONCLUSIONS: The present data suggest a clinical relevance of WT1 expression for the achieve-ment of CR and long term survival in acute leukemia. Analysis of WT1 expression with bone mar-row aspirates at the diagnosis of acute leukemia may be useful to predict prognosis.