Link to virtual “poster” presentation
Key Messages:
- The current work describes a high-throughput method for screening lymphoproliferative elements in vivo in a lentivirus format for next generation CAR-T
- A “logic-gated” HER2-targeted CAR-T was designed that preferentially recognizes HER2 in the tumor microenvironment (TME), thereby limiting on-target toxicity of low HER2 levels expressed in normal tissue
- HER2 scFvs with pH-restricted binding towards physiologic levels of HER2 were screened as CARs in primary T cells and demonstrated pH dependent cytotoxicity and cytokine release in vitro; the pH-dependence was also preserved in the context of HER2 CAR-Ts vs. ungated HER2 CARs.
- Antitumor activity and cellular kinetics were assessed in NSG mice bearing human HER2-amplified xenografts. Logic-gated HER2 CARs were capable of regressing established gastric (NCI-N87), breast (BT-474), and ovarian (SK-OV-3) tumors with HER2 amplification.
- Importantly, logic-gated HER2 CAR-T cells were also capable of completely regressing large established gastric carcinoma xenografts that had progressed on prior trastuzumab therapy.
- On-target, off-tumor safety of the CAR-Ts was assessed in NSG mice with enforced expression of human HER2 and luciferase in hepatocytes using a hydrodynamic gene delivery (HGD) model. Compared to ungated HER2 CAR-T constructs, logic-gated HER2 CAR-Ts did not eliminate hepatocyte luciferase expression with human HER2 +1 staining in mouse livers as determined by Herceptest scoring of livers at necropsy.
- In conclusion, these results demonstrate that a logic-gated HER2-targeted CAR-T can eliminate established HER2-amplified malignancies in a xenograft model, while mitigating potential on-target, off-tumor toxicity
