AML-320: A Prospective Evaluation of WT1 Gene Expression in Primary Acute Myeloid Leukemia: Bench to Bedside

Abstract

Context: Acute myeloid leukemia (AML) is a heterogeneous disease with marked variation in response to therapy. New prognostic markers, such as gene mutations, including NPM1, FLT3, and WT1, have been identified. Objective: Evaluation of WT1 gene expression and mutations, including AML-ETO, CBFB-MYH11, NPM1, FLT3-ITD, and PML-RARA, as biomarkers for therapy response in primary AML. Design: Prospective clinical research Setting: Study performed at a tertiary cancer care center. Patients or Other Participants: A total of 114 cases of diagnosed AML, having blast percentage of ≥20% blasts in peripheral blood or bone marrow on day 0, and treated with induction therapy for 28 days, after which morphological remission occurred (blast percentage ≤5%), were enrolled. Materials and Methods: RNA was extracted from blood/bone marrow samples at diagnosis (day 0) and on completion of induction therapy (day 28). Hematological workup and flowcytometric immunophenotypes were done. WT1 expression was done using real-time qPCR and was normalized against endogenous control genes: HBG2, GAPDH, and β-2-microglobulin. Detection of mutations, including AML-ETO, CBFB-MYH11, NPM1, FLT3-ITD, and PML-RARA, was done in 47 cases. Cytogenetics was done in 40 cases, and FISH for PML-RARA in 9 cases. Results: WT1 expression was seen to be reduced at day 28 in 96/114 (84.2%) cases, whereas in 18/114 (15.8%) cases, WT1 expression was seen to have increased at day 28 compared to day 0 levels. Blast count percentage in these 18 cases varied from 28% to 80%. AML-ETO mutation was detected in 14/47 (29.7%) cases, CBFB-MYH11 in 3/47 (29.8%) cases, NPM1 mutations in 5/47 (10.6%) cases, and FLT3-ITD in 8/47 (17%) cases. PML-RARA mutation was detected in 9 cases of APML (confirmed by cytogenetics and FISH in 6/9 cases). Conclusions: WT1 gene expression shows significant reduction in more than 80% of cases showing morphological remission at the end of induction therapy. WT1 expression along with blast count percentage can act as a good biomarker for assessment of remission. Molecular analysis in AML cases has diagnostic as well as prognostic significance. More prospective studies with larger sample sizes are needed to further validate these results.