Logic-gating HER2 CAR-T to the tumor microenvironment mitigates on-target, off-tumor toxicity without compromising cytotoxicity against HER2-over-expressing tumors

Wendy Zhang, Qun He, Ben Lopez, Jianfang Hu, Anirban Kundu, Michelle Andraza, Alissa R. Kerner, Gregory H. Schreiber, H. Michael Shepard, Gregory I. Frost

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