In recent years, immune-based therapies have revolutionized the field of oncology by significantly improving survival of cancer patients. Despite sustained responses, only 20% to 40% of cancer patients respond. It has become clear that the immunosuppressive environment induced by tumor through cellular and/or soluble pathways critically contribute to hinder efficient antitumor immunity. The inhibition of these immunosuppressive networks thus represents an essential prerequisite for the improvement of responses to anticancer immunotherapies. Several immune cell populations have been identified as key actors of tumor-induced immunosuppression, among which are myeloid-derived suppressor cells (MDSC) and regulatory T lymphocytes (Treg). However, in non-small cell lung cancers (NSCLC), the prognostic role of these cells, the mechanisms underlying their immunosuppressive functions, their "non-immunological" protumoral functions and their role in dampening the efficacy of immunotherapies in clinical practice are less characterized. The aim of this project is to better characterize the non immunologic functions of MDSC. We propose to assess in vitro the non-immunological pro-tumor functions of MDSC isolated from lung cancer patients