Related Experiment Video
Updated: Jun 22, 2025
Generation of Human Chimeric Antigen Receptor Regulatory T Cells
Published on: January 3, 2025
Nonsignaling extracellular spacer regulates tumor antigen selectivity of CAR T cells
Kelly T Kennewick1, Yukiko Yamaguchi1, Jackson Gibson1
1Department of Hematology and Hematopoietic Cell Transplantation, City of Hope, Duarte, CA 91010, USA.
Abstract:
Advancing chimeric antigen receptor (CAR)-engineered T cells for the treatment of solid tumors is a major focus in the field of cellular immunotherapy. Several hurdles have hindered similar CAR T cell clinical responses in solid tumors as seen in hematological malignancies. These challenges include on-target off-tumor toxicities, which have inspired efforts to optimize CARs for improved tumor antigen selectivity and overall safety. We recently developed a CAR T cell therapy targeting prostate stem cell antigen (PSCA) for prostate and pancreatic cancers, showing improved preclinical antitumor activity and T cell persistence by optimizing the intracellular co-stimulatory domain. Similar studies were undertaken to optimize HER2-directed CAR T cells with modifications to the intracellular co-stimulatory domain for selective targeting of breast cancer brain metastasis. In the present study, we evaluate various nonsignaling extracellular spacers in these CARs to further improve tumor antigen selectivity. Our findings suggest that length and structure of the extracellular spacer can dictate the ability of CARs to selectively target tumor cells with high antigen density, while sparing cells with low antigen density. This study contributes to CAR construct design considerations and expands our knowledge of tuning solid tumor CAR T cell therapies for improved safety and efficacy.
Insights
Optimizing chimeric antigen receptor (CAR) T-cell therapy for solid tumors involves tuning extracellular spacers. Spacer design influences CAR T-cell selectivity, enhancing efficacy against high-antigen tumors while sparing healthy tissues.
Area of Science:
- Cellular immunotherapy
- Oncology
- Biotechnology
Background:
- Chimeric antigen receptor (CAR) T-cell therapy shows promise for solid tumors but faces challenges like on-target, off-tumor toxicities.
- Optimizing CAR constructs for tumor antigen selectivity and safety is crucial for clinical success in solid tumor treatment.
Purpose of the Study:
- To evaluate the impact of various nonsignaling extracellular spacers on CAR T-cell selectivity and efficacy.
- To investigate how spacer length and structure influence CAR T-cell targeting of tumor cells with varying antigen densities.
Main Methods:
- Development of CAR T-cell therapies targeting prostate stem cell antigen (PSCA) and HER2.
- Systematic evaluation of different nonsignaling extracellular spacer designs within CAR constructs.
- Assessment of CAR T-cell ability to selectively target tumor cells based on antigen density.
Main Results:
- Extracellular spacer length and structure significantly impact CAR T-cell tumor antigen selectivity.
- CAR T-cells with optimized spacers demonstrate improved targeting of high-antigen-density tumor cells.
- Spacer modifications enable sparing of cells with low antigen density, potentially reducing off-tumor toxicities.
Conclusions:
- Spacer design is a critical factor in developing safe and effective CAR T-cell therapies for solid tumors.
- Tuning extracellular spacers enhances CAR T-cell specificity, improving the therapeutic window for solid tumor treatment.
- This research provides valuable insights for CAR construct design to advance solid tumor immunotherapy.
More Related Videos
Related Concept Videos
01:22T Cell Activation and Clonal Selection
Naive T cells that have not yet encountered an antigen express two primary CD...
01:27Tumor Immunotherapy