Advances in Therapies Targeting Inhibitory Checkpoint Receptors: TIGIT, LAG-3, and Beyond

Progress in our understanding of how tumor cells co-opt immune checkpoint receptor (ICR) regulation of the immune response to suppress T cell function and how these proteins interact in the tumor microenvironment has resulted in the development of a plethora of therapeutic ICR monoclonal antibodies. While anti-CTLA-4 and anti-PD-1/PD-L1 therapies have provided meaningful clinical benefit in patients with certain cancers, many patients either do not respond or experience disease progression. As such, dual blockade of PD-1/PD-L1 and ICRs with alternative mechanisms of action has the potential to improve outcomes in patients with cancer. In this review, we focus on the biology of and clinical investigations into two promising ICR targets: LAG-3 and TIGIT. The data suggest that blockade of these ICRs in combination with PD-1/PD-L1 in immune-sensitive tumors could enhance anti-PD-1 efficacy without increased toxicity, facilitate combinations with standard-of-care therapies, and extend treatment benefit to more patients.