CD4 and neoplasm: The PDAC TME consists of a large stromal component made up of an extracellular matrix, pancreatic stellate cells, cancer-associated fibroblasts (CAFs), and immune cells, with a majority of pro-tumorigenic cells such as myeloid-derived suppressor cells, tumor-associated M2-macrophages (TAMs), and regulatory T (Treg) cells; on the other hand, there are only a few anti-cancer effector cells such as M1 macrophages and effector CD4+ and CD8+ T cells.