Figure 1.

The exhausting journey of CAR T cells in the TME: In this journey, CAR T cells must be able to detect chemokines at the tumor site, effectively roll and adhere to the blood vessel wall, initiate transendothelial migration, and invade the tumor stroma. Here, the immune cells must overcome various biochemical and physical barriers to then encounter pro-tumor cells that suppress CAR T cell activity. Some CAR T cells may eventually make contact with target cancer cells that express abundant immune checkpoints, further reducing anti-tumor function.