Diagnostic and prognostic value of neuron-glial antigen 2 expression in adult acute myeloid leukemia

Abstract

Background Acute myeloid leukemia (AML) is a hematopoietic stem cell disorder characterized by a block in differentiation of hematopoiesis, resulting in growth of a clonal population of neoplastic cells or blasts. Neuron-glial antigen 2 (NG2) is not expressed by normal hematopoietic stem cells but expressed on blast cells in adult AML. NG2 has been incorporated in diagnostic panels for immunophenotyping of leukemic patients because of its positive predictive value for Mixed Lineage Leukemia (MLL) rearrangements. Aims To assess NG2 expression in adult patients with AML and its correlation with disease-free survival. Patients and methods A total of 60 patients were divided into two groups: 40 newly diagnosed patients with AML and 20 patients diagnosed as having hypersplenism used as a control group. Leukemic patients were diagnosed on the basis of clinical presentation, morphological and cytochemical examination of peripheral blood and bone marrow smears, as well as immunophenotyping criteria for diagnosis of AML. NG2 expression was evaluated in the two groups using flow cytometry. Results No significant differences were found in both age and sex in different patient groups. NG2 expression in the patient group versus control group showed a statistically significant difference. There was no statistically significant difference regarding complete blood count, lactate dehydrogenase, and erythrocyte sedimentation rate, as well as blast percentage in the peripheral blood and in the bone marrow on comparing NG2-positive group and NG2-negative group. There is a significant increase in disease-free survival and overall survival in the negative NG2 expression than in the positive NG2 expression group (P=0.043). Conclusion NG2 expression has a major role in the outcome of patients with AML. NG2 expression analysis can be used as a prognostic marker in newly diagnosed patients with AML. NG2 could be a target for therapy by using anti-NG2 antibody in a subset of patients with AML who do not respond to conventional therapy.