Adoptive immunotherapy for acute leukemia: New insights in chimeric antigen receptors

Figure 1 Schema of the general structure of a chimeric antigen receptor. The antigen recognition moiety is composed of the variable domain of heavy (VH) and light (VL) chains of the antibody, specific for a native tumor-associated antigen expressed on the surface of malignant cells. This structure is connected to the cytoplasm by a spacer, generally derived from CD8 or CD28 subunits, and a transmembrane domain. First generation chimeric antigen receptor T cells were solely composed of a single intracellular domain generally derived from CD3ζ subunit and its immunoreceptor tyrosine-based activation motifs (ITAMs), essential for Lck recruitment and full downstream T cell receptor-like signaling transduction. In order to improve engineered T cells proliferation and persistence, investigators introduced successively one (second generation) or ≥ 2 additional intracellular signaling domains (third generation). ICOS: Inducible costimulator.