Stem‐like T cells in cancer and autoimmunity

Summary Stem‐like T cells are characterized by their ability to self‐renew, survive long‐term, and give rise to a heterogeneous pool of effector and memory T cells. Recent advances in single‐cell RNA‐sequencing (scRNA‐seq) and lineage tracing technologies revealed an important role for stem‐like T cells in both autoimmunity and cancer. In cancer, stem‐like T cells constitute an important arm of the anti‐tumor immune response by giving rise to effector T cells that mediate tumor control. In contrast, in autoimmunity stem‐like T cells perform an unfavorable role by forming a reservoir of long‐lived autoreactive cells that replenish the pathogenic, effector T‐cell pool and thereby driving disease pathology. This review provides background on the discovery of stem‐like T cells and their function in cancer and autoimmunity. Moreover, the influence of the microbiota and metabolism on the stem‐like T‐cell pool is summarized. Lastly, the implications of our knowledge about stem‐like T cells for clinical treatment strategies for cancer and autoimmunity will be discussed.