What are the differences between TCRs, TILs, and CAR-Ts in immunotherapy?

TCRs (T-cell receptors) are expressed by T cells, and profoundly and actively influence lymphocyte activity in modulating the immune response. Manipulating T cell receptor properties and numbers to boost immune responses is a very active area of immunotherapy research. TILs (tumor-infiltrating lymphocytes) are being actively investigated for their anti-cancer properties, as tumor biopsies often contain immune cells conditioned to the tumor microenvironment. These cells can be harvested, studied, and subjected to chemokine fortification prior to reintroduction. Finally, CAR-T cells (chimeric antigen receptor-T cells) refers to genetically engineered T cells which express surface receptors specifically targeting cancer cell-expressed surface antigen.1

1. C.J. Turtle et al, "CD19 CAR–T cells of defined CD4+:CD8+ composition in adult B cell ALL patients," J Clin Invest 126(6):2123-2138, 2016.