TArgeting acute myeloid Leukemia immunosuppressive microEnvironment by combined IDO1 inhibiTion and PD-1 blockadE

The most frequent acute blood cancer in adults are acute myeloid leukemia, which is an aggressive disease originating from stem cells of the bone marrow. Untreated 3 months survival is approximately 50%, and above the age of 70 years 3 years survival is below 25%. The majority of patients is above 70 years, and above the age of 70 years the yearly occurrence of 17 per 100 000. To improve patients’ outcomes, therapy that use the immune system - immunotherapy - have the potential to circumvent some of the mechanisms leading to treatment failure. Unfortunately, immunotherapy against AML has been unsatisfactory. The major reason for that relies on the largely incomplete understanding of the interactions between leukemia and immune cells at the microscale environment. This interaction in AML microenvironment of the bone marrow is the scene of this project. Methods: Bone marrow samples will be collected from a cohort of AML patients receiving the combination of standard therapy of azactidine and venetoclax. Azactidine and venetoclax represents a recent backbone for innovative therapeutic strategies in AML through the addition of novel immunomodulatory drugs. The project activities will be structured in four integrated work packages. Work Package 1: Project Management, Ethics, Dissemination, and Training, capacity building activity. Work Package 2: Characterization of bone marrow microenvironment by advanced molecular analyses including tissue organization. Work Package 3: Test tube experiment to model mechanisms of failure to immunotherapy. WP4: Integrated analysis of clinical and large molecular data sets. Expected results and potential impact: The expected discovery of microenvironment mechanisms will improve selection of therapy to specific patients. New diagnostic tools that will describe the bone marrow microenvironment will start a gradual introduction into clinical use.

Survival of Acute Myeloid Leukemia (AML) is poor. To improve patients’ outcomes, immunotherapies have the potential to circumvent some of the mechanisms leading to treatment failure, but their exploitation against AML has been unsatisfactory. The major reason for that relies on the largely incomplete understanding of the interactions between leukemia and immune cells in AML microenvironment. In that, the causative role of immunosuppressive bone marrow (BM) pathways, including overexpression of immune checkpoint (IC) receptors, such as PD-1 and tryptophan degradation via indoleamine 2,3- dioxygenase (IDO)1 is not fully elucidated. Methods: BM samples will be collected from a cohort of AML patients receiving the combination of azactidine and venetoclax, which represents the backbone for innovative therapeutic strategies in AML through the addition of novel compounds, such as immunomodulatory drugs. The project activities will be structured in 4 interconnected and integrated work packages. WP1: Project Management, Ethics, Dissemination, and Training, capacity building activity. WP2: Characterization of BM microenvironment: mass cytometry, single-cell RNA-seq, immunometabolism, and epigenetics (multi-omics). WP3: Experimental in vitro modeling to validate mechanisms of resistance (co-cultures, cell interactions). WP4: Methodology, Biostatistics, and Bioinformatics: integrated analysis of clinical and multi-omics data. Expected results and potential impact: The expected discovery of microenvironment-based mechanisms of susceptibility to immunotherapies will affect clinical practice by improving patients’ selection. The expected development of a novel platform for BM microenvironment investigation will impact technology transfer by providing advanced diagnostic tools.