Could Immunophenotype Guide Molecular Analysis in Patients with Myeloid Malignancies

Objective: Immunophenotype has been correlated with molecular aberrations in several studies. The aim of this study was the discovery of immunophenotypic features related to mutations in AML and MDS patients connected to prognostic factors. Moreover, an effort to evaluate a method for the detection of the most common NPM1 mutations of exon12 and Internal Tandem Duplications (ITD) mutations of FLT3 gene by flow cytometry was performed. Method: Patients with de novo myeloid neoplasms [ AML and MDS (AML-M3 patients were excluded)] were included. FLT3/ITD/TKD and NPM1 mutations were detected by PCR and fragment analysis. The immunophenotypic analysis was performed by multi-dimensional flow cytometry (FC) with a standardized panel of monoclonal antibodies on peripheral blood or bone marrow samples. Nucleophosmin Antibody and CD135 were used for the mutations immunophenotypic detection. Results: NPM1 and/or FLT3 mutations correlated with low or no expression of more immature cells markers such as CD34, CD117, HLADR, as well as higher expression of more mature markers such as CD11b. The higher expression of CD33 should be mentioned as well. The presence of NPM1mut and FLT3/ITD does not seem to be detectable by FC at least using these two monoclonal antibodies. The presence of CD7 aberrant lymphoid marker’s expression was associated with FLT3mut, NPM1wt genotype. CD56 or CD2 positivity was found only in patients’ samples negative for NPM1 and/or FLT3 mutations. Conclusions: Certain immunophenotype findings including the presence of aberrant lymphoid markers may be indicative of the presence of mutations in NPM1 and FLT3 linked to prognosis.