CD8A and neoplasm: Sommermeyer et al. determined an ideal cell cocktail to contain 1:1 CD8+ CAR-TCM to CD4+ CAR-TN cells in a mouse model of Raji lymphoma [7], suggesting that IL-2 produced by CD4+ cells drives optimal proliferation of CD8+ CAR-T cells, which are then the main component of anti-tumor cytotoxicity [7,19,24,25].