Epigenetic engineering for optimal chimeric antigen receptor T cell therapy

Recent advancements in cancer immunotherapy, such as chimeric antigen receptor (CAR)‐engineered T cell therapy and immune checkpoint therapy, have significantly improved the clinical outcomes of patients with several types of cancer. To broaden its applicability further and induce durable therapeutic efficacy, it is imperative to understand how antitumor T cells elicit cytotoxic functions, survive as memory T cells, or are impaired in their effector functions (exhausted) at the molecular level. T cell properties are regulated by their gene expression profiles, which are further controlled by epigenetic architectures, such as DNA methylation and histone modifications. Multiple studies have elucidated specific epigenetic genes associated with T‐cell phenotypic changes. Conversely, exogenous modification of these key epigenetic factors can significantly alter T cell functions by extensively altering the transcription network, which can be applied in cancer immunotherapy by improving T cell persistence or augmenting effector functions. As CAR‐T cell therapy involves a genetic engineering step during the preparation of the infusion products, it would be a feasible strategy to additionally modulate specific epigenetic genes in CAR‐T cells to improve their quality. Here, we review recent studies investigating how individual epigenetic factors play a crucial role in T‐cell biology. We further discuss future directions to integrate these findings for optimal cancer immunotherapy.