T Cells Engineered With Chimeric Antigen Receptors Targeting NKG2D Ligands Display Lethal Toxicity in Mice
Heather VanSeggelen1, Joanne A Hammill1, Anna Dvorkin-Gheva1
1Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, McMaster University, Hamilton, Ontario, Canada.
Abstract:
Ligands for the NKG2D receptor are overexpressed on tumors, making them interesting immunotherapy targets. To assess the tumoricidal properties of T cells directed to attack NKG2D ligands, we engineered murine T cells with two distinct NKG2D-based chimeric antigen receptors (CARs): (i) a fusion between the NKG2D receptor and the CD3ζ chain and (ii) a conventional second-generation CAR, where the extracellular domain of NKG2D was fused to CD28 and CD3ζ. To enhance the CAR surface expression, we also engineered T cells to coexpress DAP10. In vitro functionality and surface expression levels of all three CARs was greater in BALB/c T cells than C57BL/6 T cells, indicating strain-specific differences. Upon adoptive transfer of NKG2D-CAR-T cells into syngeneic animals, we observed significant clinical toxicity resulting in morbidity and mortality. The severity of these toxicities varied between the CAR configurations and paralleled their in vitro NKG2D surface expression. BALB/c mice were more sensitive to these toxicities than C57BL/6 mice, consistent with the higher in vitro functionality of BALB/c T cells. Treatment with cyclophosphamide prior to adoptive transfer exacerbated the toxicity. We conclude that while NKG2D ligands may be useful targets for immunotherapy, the pursuit of NKG2D-based CAR-T cell therapies should be undertaken with caution.
Insights
Chimeric antigen receptor (CAR)-T cell therapy targeting NKG2D ligands shows potential but causes significant toxicity in mice. Researchers engineered NKG2D-based CAR-T cells, observing strain-specific differences in efficacy and toxicity, necessitating caution in clinical development.
Area of Science:
- Immunology
- Cancer Immunotherapy
- Cellular Therapy
Background:
- NKG2D receptor ligands are upregulated on various tumors, presenting them as potential targets for cancer immunotherapy.
- Chimeric antigen receptor (CAR)-T cell therapy offers a promising approach to redirect T cells against cancer cells.
Purpose of the Study:
- To engineer and evaluate NKG2D-based CAR-T cells for targeting tumors.
- To assess the in vitro functionality and in vivo safety and efficacy of different NKG2D-CAR configurations.
Main Methods:
- Engineered murine T cells with two distinct NKG2D-based CARs (NKG2D-CD3ζ and NKG2D-CD28-CD3ζ) and coexpressed DAP10.
- Assessed CAR expression and in vitro functionality in BALB/c and C57BL/6 T cells.
- Evaluated in vivo toxicity and effects of adoptive transfer in syngeneic mouse models, with and without cyclophosphamide pre-treatment.
Main Results:
- In vitro, BALB/c T cells exhibited greater CAR functionality and surface expression than C57BL/6 T cells.
- Adoptive transfer of NKG2D-CAR-T cells led to significant clinical toxicity, including morbidity and mortality, varying by CAR design and mouse strain.
- Cyclophosphamide treatment prior to T cell transfer exacerbated observed toxicities.
Conclusions:
- NKG2D ligands are viable targets for immunotherapy, but NKG2D-based CAR-T cell therapies require careful consideration due to significant toxicity.
- Strain-specific differences in T cell function impact both efficacy and toxicity, highlighting the need for personalized approaches.
- Further research is warranted to mitigate toxicity and optimize NKG2D-CAR-T cell therapy for safe and effective cancer treatment.
