Table 1.

Defining characteristics of CARs and TCRs

	Chimeric antigen receptors (CARs)	T cell receptors (TCRs)
Signal amplification	Determined by synthetic biology	Determined by evolution
Affinity	High and can be engineered	Low but can be enhanced
Target	Cell surface proteome	Intracellular proteome
MHC dependency	Independent	Required
Safety	Toxicities possible due to antigen expression on normal tissues	Toxicities may be difficult to predict
Mechanisms of resistance	Antigen loss	Antigen loss, MHC loss/downregulation, defects in antigen presentation