Characterization of T cell dysfunction in AML patients during treatment with hypomethylating agents plus Venetoclax

In AML there is an adaptive immune dysfunction, involving above all T lymphocytes, with a prevalence of Tregs and Th17 producing IL-10; than T cells in AML exhibit features of senescence, exhaustion and anergy. This study project aims to provide comprehensive insights into longitudinal immune landscape in AML, focusing on characterization of T cell dysfunction in patients candidates for treatment with Azacitidine or Decitabine, alone or in combination with Venetoclax, both in first line and in the relapsed/ refractory setting, using different methods. Firstly, we have collected retrospective data about patients affected by newly diagnosed AML, candidates for Azacitidine single agent. For those patients, peripheral blood and bone marrow samples, have been analyzed using flow cytometry, in order to characterize T cells (as T cell subpopulations, and as their expression of the immune checkpoints). We have found that PD1 expression by T cells resulted to be high, leading to an impaired T cell function and to tumor escape; furthermore, in our cohort of treatment naïve AML patients, the mean concentration of Tregs in peripheral blood was 18% of CD4+ T cells. Using the same flow cytometry characterization, in a small cohort of patients responsive to hypomethylating agents plus Venetoclax, we found a low expression of all the immune checkpoints and a lower concentration of immunosuppressive Tregs in peripheral blood (about 7% of CD4+ T cells), compared to treatment naïve patients. Because of cell sorting by flow cytometry has some limitations, we then used a RNA sequencing for the prediction of immune cell subtypes abundances, in patients candidate to first line or salvage therapy with Venetoclax plus an hypomethylating agent. With CYBERSORT, we found that, in AML patients, immune cells (both T helper and natural killer cells) were mostly in a rest functional state, and this could contribute to immune evasion.