Change in Programmed Death-1 And Inducible Costimulator Expression in Patients with Acute Myeloid Leukemia Following Chemotherapy and Its Cytogenetic Abnormalities

Background: Programmed death-1 (PD-1) and inducible costimulator (ICOS) are immune checkpoint receptors participating in tumor immune evasion, which counters the activation signal provided through the T-cell receptor ligation. This study aimed to investigate the relationship between the expression of PD-1 and ICOS on mononuclear cells (MNCs) isolated from the peripheral blood of acute myeloid leukemia (AML) patients and their response to induction chemotherapy. Materials and Methods: Peripheral blood samples (5cc) were collected from 56 AML patients at first diagnosis before and after the induction therapy regimen for AML. PD-1 and ICOS expression were analyzed in all patients before and after the standard induction therapy regimen. Results: The expression of PD-1 and ICOS significantly decreased (66.7 and 16.3 fold, respectively) in AML patients following chemotherapy compared to its baseline value (P=0.01 and P=0.001, respectively). The expressions of PD-1 and ICOS were significantly different between favorable and poor risk groups. Conclusions: Lower PD-1 and ICOS expressions on the surface of MNCs before induction therapy were associated with a better response to treatments. In addition, PD-1 and ICOS expression on MNCs decreased after induction therapy.