Table 1.

Intracellular modification and function of CAR-T.

Generation	CAR-T Intracellular Modification	Efficacy
First	CD3ζ	T cells activate in vitro and have the lethality of conventional T cells but fail to proliferate and survive.
Second	CD28-CD3ζ	With the addition of a costimulatory molecule, the survival time in vivo is extended, and the proliferation ability and the killing toxicity is increased.
Third	CD28-CDl34-CD3ζ or CD28-CDl37-CD3ζ	Addition of two different costimulatory molecules improves the increment ability and killing toxicity.
Forth	Add a suicide gene or CAR-T secretes specific cytokines	Addition of suicide genes or release of immune factors refines control.
Fifth	Universal CAR-T	No individual restrictions, can be large-scale production and treatment.