Expression of WT1, Survivin, and TERT genes in Acute Myeloid Leukemia: Important Clinical Prognostic Indicators Envisioning Triple Immunotherapeutic Targets.

Patients with acute myeloid leukemia (AML) show overexpression of Wilms tumor 1 (WT1), Survivin, and telomerase reverse transcriptase (TERT) genes. High levels of expression of the WT1 gene or its mutant derivatives are correlated with the clinical outcome and, therefore, both WT1 and Survivin are valuable immunotherapeutic targets in AML and critical prognostic indicators for minimal residual disease (MRD). Quantitative assessment of these gene transcripts by real-time quantitative PCR (RQ-PCR) may be useful for predicting clinical outcome and prognosis in AML, and for detection of MRD.

We determined the expression of these genes, together, in bone marrow (BM) and peripheral blood (PB) mononuclear cells in 179 patients with newly diagnosed AML and 15 healthy normal controls using RQ-PCR. The molecular profiles were then evaluated with the patients' clinical characteristics, including the known important prognostic indicators such as age, cytogenetics, receptor tyrosine kinase (RTK) mutations, aberrant expression of lymphoid markers, and serum ferritin levels at diagnosis, etc.

The median levels of WT1, Survivin, and TERT expression in healthy controls were 10.41 (range, 0.74 – 23.26), 4.56 (range, 0.2 – 44.6), and 0.22 (range, 0.01 – 4.59), respectively. Higher levels of WT1, Survivin, and TERT gene expression than the maximum copy numbers in healthy controls were found in 73.99%, 72.5%, and 57.8% of BM, and in 62.2%, 46.4%, and 41.1% of PB from the patients, respectively. Elevated levels of paired expression of WT1 and Survivin, WT1 and TERT, and Survivin and TERT were found in 80%, 77%, and 68% in BM and in 86%, 80%, and 84% in PB of patients, respectively. We found that 85% of BM and 90% of PB from the patients expressed at least one of these three genes at elevated levels. The Kaplan-Meier estimated 5-year overall survival (OS) and event-free survival rates in the whole population of patients were 36% (95% CI, 31% – 41%) and 37% (95% CI, 31% – 43%), respectively. Of the 157 treated patients, 84 (53.5%) were in continuous complete remission (CR) at a median follow-up of 16 months (range, 1–60), and 23 (14.6%) died with treatment-related mortality (TRM). We evaluated whether the presence or absence of any single or combination of three genes in the patients affected CR and survival rates. Among the three genes examined, the most influential factor for achieving CR was Survivin (P = 0.0026). Interestingly, the levels of serum ferritin (P = 0.0286) and WT1 (P = 0.0202) were significant factors for TRM. Both WT1 and Survivin levels were closely correlated with conventional cytogenetic abnormalities. Notably, serum ferritin levels were correlated with TERT expression. Finally, c-kit mutations tended to show an inverse correlation with WT1 expression, but there was no significant correlation between FLT3-ITD mutations and expression of any of the three genes examined in this study.

We found significant correlations between WT1, Survivin, and TERT gene expression by RQ-PCR, and critical parameters during induction chemotherapy for AML. As our findings were based on a single disease entity, i.e., adult AML, they suggest that the expression of three genes may be critical for the immunobiology of AML to influence the clinical outcome. Thus, the results of this study suggest that we can develop a novel strategic immunotherapeutic tool, targeting three antigens together, to eradicate MRD by enhancing the graft-versus-leukemia effect following allogeneic hematopoietic stem cell transplantation in patients with relapse high-risk AML, in a manner tailored to individual patients.

No relevant conflicts of interest to declare.