The result of the above study shows the IL-2-dependent antagonistic effect of Treg cells [36] versus the agonistic IL-2-dependent effect of proliferative CD8+ T cells on anti-tumor activity of CD28-CD3ζ-CAR-T cells demonstrated by other groups [39,40,41], and demonstrates that the balance of Treg cells to effector cells ratio is an important marker of effective immunotherapy [40]. Here, CD28 is linked to neoplasm.