PD1 expression on bone marrow T-cells in newly diagnosed Egyptian AML patients: Correlation with hematological parameters, aberrant antigens expression, and response to induction therapy.

Background: Programed cell death protein 1 (PD-1) is a key mediator for the development of T cell exhaustion that develops in response to persistent antigen stimulation.

Aim: In this study, we measured PD1 expression on CD3 positive bone marrow T-lymphocytes in newly diagnosis AML patients and its relation to clinical/ prognostic outcomes in addition to response to induction therapy (day 28).

Methods: This study was conducted on 59 newly diagnosed AML patients and 20 healthy controls. Complete blood counts, flow cytometry using acute leukemia panel in addition to PD1 monoclonal antibodies were performed on bone marrow lymphocytes (CD3+), whereas cytogenetic/molecular studies were used to determine risk group. The patients' remission status following induction therapy was determined.

Results: PD1 was brightly expressed in 91.5% of the cases than control sample with highly significant difference ( = .001). A cutoff of 3.5 for mean fluorescence intensity was used to divide patients into two groups (higher vs normal PD1 expression). A significant difference between the two groups regarding platelet count and aberrant CD7 expression ( = .007 and .023, respectively) was found. Those normally expressed PD1 respond better to induction therapy.

Conclusion: PD1 expression on BM T-cells had a predictive value and providing an immunotherapeutic target for AML.