Fig. 1

Potential outcomes of CAR T cell therapy in a patient with T cell disease. Upon re-infusion into a patient, CAR T cells recognize their cognate antigen, expanding upon this recognition, and initiating an attack. However, due to shared antigen expression on CAR T cells, normal T cells, and tumor cells, numerous outcomes can be observed. CAR T cells target tumor cells as intended, reducing tumor burden. However, without further engineering, the CAR-modified T cells are likely to express the targeted antigen as well, resulting in fratricide. CAR T cells would also target healthy T cells, resulting in unintended T cell aplasia. Lastly, CAR T cell therapy involves isolating normal T cells from malignant T cells for CAR-modification. A single malignant cell contaminating this population can result in masking of the antigen, leading to antigen-positive relapse. *Figure was created using BioRender