IL15 and neoplasm: Many studies concur with our observations, pointing to a superior antitumor potential of CD4 CAR-T cells when administered as single therapy,36 37 40–42 while some others sustain the superiority of CD8 CAR-T cells, at least in the context of B-cell malignancies.23 43 Such discrepancies can be ascribed to the employment of different mouse models (xenograft vs syngeneic), tumor types (solid vs hematological) and manufacturing procedures (IL-2 vs IL-7/IL-15).