Figure 3.

Strategies to avoid on-target/off-tumor toxicity. (A) Targeting of neoantigens generated by mutations in tumor cells. (B) Boolean logic-gated CAR-T cells include AND gated CARs, sequential AND gated CARs, and NOT gated CARs. First, AND gated CARs consist of 2 separate CAR molecules of which the first provides only the activation signal and the second the necessary costimulation. Second, sequential AND gated CARs are placed under the control of an inducible promoter that can only be activated in response to signals mediated from a constitutively expressed synthetic Notch receptor (synNotch). Binding of the target antigen results in proteolytic cleavage of the Notch core region and the release of the transcription factor from the cell membrane, after which it translocates to the nucleus and drives the expression of an “effector” CAR. Third, NOT gated CARs use an inhibitory CAR (iCAR), where killing will only be obtained if target cells only engage with one of the receptors present on the CAR-T cells. C. Autologous CD33 knock-out in hematopoietic stem cell progenitors generates a hematopoietic system resistant to anti-CD33 CAR T-cell therapy. Created with BioRender.com. CAR = chimeric antigen receptor.