Role of Tim-3 in regulating tumorigenesis, inflammation, and antitumor immunity therapy

Over the past decade, cancer immunotherapy, such as immune checkpoint inhibitors (ICRs), has attained considerable progresses in clinical practice. T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) act as next ICRs, and originally function as a co-inhibitory receptor expressed on interferon (IFN)-γ producing CD4+ and CD8+ T-cells. Furthermore, Tim-3 has also been found to express on innate immune cells and several types of tumors, signifying the pivotal role that Tim-3 plays in chronic viral infections and cancer. In addition, Tim-3 and multiple ICRs are concurrently expressed and regulated on dysfunctional or exhausted T-cells, leading to improved antitumor immune responses in preclinical or clinical cancer therapy through co-blockade of Tim-3 and other ICRs such as programmed cell death-1 (PD-1). In this review, the biological characteristics of Tim-3 and the function of Tim-3 in regulating tumorigenesis and inflammation have been summarized. The usage of a single blockade of Tim-3 or in combination with multiple immunotherapy regimens have drawn attention to antitumor potential as a target for immunotherapy.