IL1RL1 and cancer: However, in cancer patients and tumor-bearing mice, many tumor-infiltrating Th1 and CD8+ T cells are unresponsive due to immunosuppressive mechanisms (77). The IL-33/ST2 signaling pathway is a potent TME regulator, recruiting immune cell populations that reshape the TME to either promote malignancy or induce tumor regression, particularly those related to type 2 and regulatory immune responses (78).