“…On the other hand, the TME can provide an immunosuppressive niche to negatively regulate immune effector cells and facilitate the malignant progression of cancer (Ho et al, 2020), and causes the resistance of PC against various treatments such as chemotherapy, targeted therapy, and immunotherapy (Balachandran et al, 2019). The major immunosuppressive cell types in the TME of pancreatic cancer are tumor-associated macrophages (TAMs), myeloidderived suppressor cells (MDSCs), regulatory T cells (Treg), TH17, and tolerogenic DCs (Bronte and Tortora, 2016;Zhu et al, 2017;Ligorio et al, 2019;Zhang et al, 2020). These immunosuppressive cells promote tumor progression through a variety of mechanisms, including the direct mediation, inhibition of tumor-killing immune cells, induction of angiogenesis and lymphoangiogenesis (Ho et al, 2020), and promotion of metastasis.…”