CD274 and cancer: 126 Thus, removing Treg cells from the tumor microenvironment or inhibiting their activity is a strategic approach to cancer treatment. In addition, hypoxia in the TME protects cancer cells from immunological attack and suppresses tumor-killing. 127,128 It influences glucose metabolism, angiogenesis, cell proliferation, invasion, and metastasis, promotes the expression of PD-L1 in tumor cells, and suppresses the T-cell response.