CD19 and breast cancer: Vorinostat downregulates the expression of CTLA‐4 and TET2, which are implicated in the immunosuppressive effects of CAR‐T cells.[44] Likewise, birinapant is a synthetic small molecule that acts as a peptidomimetic of the second mitochondrial‐derived activator of caspases (SMAC).[45] Dufva and colleagues have demonstrated that birinapant can augment the antitumor effectiveness of CD19 CAR‐T cells.[46] Furthermore, numerous studies have proved the inhibitory effects of everolimus on BC.[47] Therefore, we detected the killing efficiency when these drugs were combined with CAR‐T cells.