WT1 Synonymous Single Nucleotide Polymorphism rs16754 Correlates With Higher mRNA Expression and Predicts Significantly Improved Outcome in Favorable-Risk Pediatric Acute Myeloid Leukemia: A Report From the Children's Oncology Group

Purpose To analyze the prevalence and clinical implications of Wilms' tumor 1 (WT1) single nucleotide polymorphism (SNP) rs16754 in the context of other prognostic markers in pediatric acute myeloid leukemia (AML). Patients and Methods Available diagnostic marrow specimens (n = 790) from 1,328 patients enrolled in three consecutive Children's Cancer Group/Children's Oncology Group trials were analyzed for the presence of SNP rs16754. SNP status was correlated with disease characteristics, WT1 expression level, and clinical outcome. Results SNP rs16754 was present in 229 (29%) of 790 patients. The SNP was significantly more common in Asian and Hispanic patients and less common in white patients (P < .001). SNP rs16754 was also less common in patients with inv(16) (P = .043) and more common in patients with -5/del(5q) (P = .047). WT1 expression levels were significantly higher in patients with rs16754 or with WT1 mutations compared with WT1 wild-type patients (P = .021). Five-year overall survival (OS) for patients with and without the SNP was 60% and 50%, respectively (P = .031). Prognostic assessment by risk group demonstrated that in patients with low-risk disease, OS for those with and without SNP rs16754 was 90% versus 64% (P < .001) with a corresponding disease-free survival of 72% versus 53% (P = .041). Conclusion The presence of SNP rs16754 was an independent predictor of improved OS; outcome differences were most pronounced in the low-risk subgroup. The high prevalence of WT1 SNP rs16754, and its correlation with improved outcome, identifies WT1 SNP rs16754 as a potentially important molecular marker of prognosis in pediatric AML.