OSE-172 (Effi-DEM), a new generation immune checkpoint inhibitor, is a monoclonal antibody that blocks specific suppressor cells present in the tumor microenvironment, “Myeloid-Derived Suppressor Cells” (MDSC), and macrophage cells associated with tumors called “Tumor Associated Macrophages” (TAM). In immune-oncology, OSE-172 could be developed as a monotherapy or be combined with other immunotherapies or checkpoint inhibitors, already registered or in development, which act on other targeted cells of cancer immunity.
The formation of an immunosuppressive tumor environment is regularly observed in cancer progression and involves several cell lines with suppressor functions. Regulator T lymphocytes (or Treg) exert a suppressor activity, and the first generation of checkpoint inhibitors act on these regulator T cells (through the ligands of CTLA-4, PD-1 and PDL-1).
Beyond the effect of regulator T cells, a differentiation of Myeloid-Derived Suppressor Cells (MDSC) that inhibits effector T lymphocyte functions (by the secretion of TGF-beta and IL-10 mediators) is also observed. MDSC are broadly expressed in the tumor environment. In parallel, Tumor Associated Macrophages (TAM) with suppressor functions accumulate locally and allow tumor growth.
Presently, there are no available treatments to help reduce or eliminate MDSC and TAM. A second generation of checkpoint inhibitors could therefore be developed, acting on these new suppressor immune cell targets.