CRISPR-Cas9 screen identifies potential novel regulators of CD8 +T cell dysfunction

Abstract

Abstract CD8 +T cells directly target and kill cancer cells and are required for effective antitumor immunity and response to immunotherapy. However, CD8 +T cells may become dysfunctional and exhausted when exposed to chronic antigen stimulation during cancer. Dysfunction is characterized by increased expression of inhibitory receptors as well as impaired effector function, yet the genetic mechanisms controlling dysfunction remain poorly understood. To address this gap, we have developed an ex vivo restimulation model that recapitulates features of CD8 +T cell dysfunction seen within the tumor microenvironment. By coupling this system with genome-wide CRISPR-Cas9 loss of function screening, we have identified genetic factors which may play a novel role in the progression of CD8 +T cells to a dysfunctional state. Deletion of select factors restored CD8 +T cell survival and effector function during chronic restimulation conditions in vitro, including tumor cell killing capability. Future studies will focus on further characterizing the phenotypic and functional roles of these regulators, as well as translating this model to primary human CD8 +T cells. In summary, we have uncovered novel potential regulators of CD8 +T cell dysfunction and targeting these genes may improve antitumor immunity and immunotherapy efficacy.