Tissue-resident memory T cells in tumor immunity and immunotherapy

Tissue-resident memory T cells (T(RM)) represent a heterogeneous T cell population with the functionality of both effector and memory T cells. T(RM) express residence gene signatures. This feature allows them to traffic to, reside in, and potentially patrol peripheral tissues, thereby enforcing an efficient long-term immune-protective role. Recent studies have revealed T(RM) involvement in tumor immune responses. T(RM) tumor infiltration correlates with enhanced response to current immunotherapy and is often associated with favorable clinical outcome in patients with cancer. Thus, targeting T(RM) may lead to enhanced cancer immunotherapy efficacy. Here, we review and discuss recent advances on the nature of T(RM) in the context of tumor immunity and immunotherapy.