Table 1.

Generations of chimeric antigen receptor T cells for acute lymphoblastic leukemia.

Generation	Intracellular Costimulatory Signaling Domains
1st	CD3 ζ
2nd	CD3 ζ and one costimulatory domain (CD28 or CD27 or 4-1BB or OX40(CD134))
3rd	CD3 ζ and two costimulatory domains
4th	2nd generation CAR T-cell and cytokine/costimulatory ligand transgene with IL12 expression
5th	Similar to 4th generation CAR construct with addition of intracellular domain of the IL-2 receptor

CD: cluster of differentiation; ζ: zeta; CAR T: chimeric antigen receptor T cell.