CD19 and neoplasm: The downregulation of CD 58 in tumor cells impedes the establishment of IS with CAR-T cells (including CD19 CAR-T cells, CD20 CAR-T cells, and tandem CD19/20 CAR-T cells), leading to diminished CAR cell signaling, reduced cell growth, and impaired cytotoxicity, hence contributing to resistance against CAR-T cell therapy (12) (See Figure 3).