Combined overexpression of WT1 and BAALC genes May Predict AML evolution in MDS Patients
Authors: Avenoso Daniele , De Astis Enrico , Colombo Nicoletta , Grasso Raffaella , Bergamaschi Micaela , Minetto Paola , Aquino Sara , Lovera Davide , Cruciani Fabio , Guolo Fabio , Ballerini Filippo , Clavio Marino , Canepa Letizia , Pierri Ivana , Marani Carlo , Gobbi Marco , Miglino Maurizio 
Published: October 2019

Abstract

Background and aims
Myelodisplastic syndromes (MDS) are a group of hemopoietic disorder characterized by an impaired blood cell production, morphologic dysplasia and peripheral cytopenias; they are the most common hematologic neoplastic disorder and its diagnosis relays on morphologic evaluation, associated to a karyotypic assay.
In order to predict the outcome of patients affected from these disorders, knowing that the order of survival can be extremely variable, several prognostic index were developed such as International Prognostic Score Sistem (IPSS) or the most usefull WHO-Prognostic Score Sistem (WPSS).
On the contrary of acute leukemia, these disorders have not a biomolecular profile evalutation of intrinsic markers able to stratify patients in different prognostic risk groups.
The aim of our study is to assess the risk of leukemic evolution, in MDS patients, on the basis of the levels expression of WT1 and BAALC at disease diagnosis, and to evaluate the leukemia free survival (LFS) at 6-12-24-36 months of follow up, among the different risk category according to IPSS and irrespectively of treatment.

Materials and method
In five years we analized 102 patients with a diagnosis of MDS divided according to the WHO classification such as follows: 38 AR, 1 AR with del(q5), 21 aREB-1, 23 AREB-2, 3 chronic myelomonocitic leukemia, 1 RARS, 1 MDS, 11 RCMD, 1 5q- syndrome, 2 suspected MDS.
According to IPSS 58 belonged to the low risk category, 21 to the intermediate-1, 23 to the intermediate-2/high risk.
Cytogenetic assay showed 20 people with an abnormal karyotype, 8 of them fallen into the high risk class and 12 into the intemediate risk.
Low risk and intermediate-1 patients were treated only with supportive care; high risk patients were treated with hypomethylating agents. Iron chelation were used when necessary. Lenalidomide was used in the only case of 5 q- syndrome
Samples of bone marrow were analized with Real-Time quantitave PCR and levels of WT1 and BAALC expression were determinated.
Molecular datas were analized with X-square Test and a significant association was recorded between overexpression of the genes evaluated (WT1 higher than 100 copy numbers and BAALC higher than 1000 copy numbers) and the probability of develop acute myeloid leukemia ( AML ).

Results
Nine out of 102 patients showed an isolated WT1 hyperexpression (3 of them developed an AML ), in 15 cases we reported an isolated BAALC overexpression (3 of them developed an AML ), while 13 out 18 patients ( 72% ) with combined WT1 and BAALC overexpression developed AML within an average time of 6 months; instead only 5% of patients, which expressed low levels of WT1 and BAALC, developed AML within the interval of observation.
In particulary a combined high expression of WT1 and BAALC were strongly associated with an high risk to develop leukemia and a short LFS, especially in INT-1 subset.
After that we calculated the LFS, divided for the risk category at 6-12-24-36 months of follow up.
Patients with combined overexpression of WT1 and BAALC showed a LFS of 40% at 6 months of follow up and 0% at 24 months.

Conclusion
MDS have a great variable survival, and the current approach to these diseases relays on morphological evaluation, karyotypic assay and need of transfusional support; gene expression could be a promising system to predict the prognosis in these patients.
Analysis of gene expression, which belong to AML evaluation, allows to divide patients in several risk groups; furthermore is not the single gene evaluation that is more predictable but a combined assay.
With this method, which seems to be more realiable than IPSS, we could find that a great percentage of patients with levels of WT1>100 and BAALC >1000, indipendently from karyotypic status and treatment, developed AML and have a shorter LFS than the population with WT1 <100 and BAALC < 1000.

Disclosures:
No relevant conflicts of interest to declare.