SUMMARY:
UCLA researchers in the Department of Microbiology, Immunology and Molecular Genetics, and the Department of Molecular and Medical Pharmacology have recently developed a novel approach which improves the kinetics and specificity of CAR T-cell therapy.
BACKGROUND:
Chimeric antigen receptor (CAR) T-cell therapy makes use of reengineered T-cells to target and clear cancer cells. Conventional CAR-T cell therapy begins by collecting T-cells from patients; then, in a laboratory setting, the cells are genetically modified to express a CAR molecule on their surface. A large population of these designer cells are then reintroduced back into the patient where they attack and kill cancer cells expressing the target molecule of the CAR. While CAR-T cell therapy has seen success for the treatment of blood cancers and research has been progressing to expand its use to other cancer types, specificity limitations hamper efforts. Namely, because most cancer-associated antigens have some level of ubiquitous expression in healthy tissues, CAR-T cells have been found to not only kill the cancer cells that express the target antigen but also normal healthy tissues that express it, causing “on-target, off-tumor’ toxicity. Due to this complication in the treatment, many clinical trials have been terminated due to the dose-limiting toxicities.
One strategy employed to overcome this specificity concern involves engineering Boolean logic gated CARs that can respond to multiple antigen targets. A promising subset of this approach makes use of a typical activating signaling construct targeting one antigen (e.g. antigen A) in conjunction with an inhibitory signaling construct targeting another antigen (e.g. antigen B) for an “AND-NOT” response; The intended effect of such a system would be activation of a CAR-T cell only when a cancer marker: antigen A, but not a healthy cell marker: antigen B, is present, thereby improving specificity of T cell response. To advance application of these designs to the clinic, however, the effectiveness of inhibitory receptor constructs needs to be improved.
INNOVATION:
Researchers at UCLA lead by Dr. Owen Witte have improved the inhibitory kinetics of CAR-T cell therapy by designing a novel dual-signaling inhibitory CAR (iCAR) system. The research team screened a panel of iCAR constructs composed of intracellular inhibitory domains fused to existing CAR framework necessary for antigen recognition previously designed in the laboratory. Using a T cell activation reporter assay, candidates that effectively inhibited T-cell activation were progressed to develop constructs containing multiple copies of the most effective inhibitory domains. These novel dual-signaling iCARs showed marked improvement in inhibition kinetics. The novel iCAR constructs could be combined with other existing CARs to prevent/reduce the “on-target, off-tumor” toxicity that is associated with many existing CAR T-cell therapy embodiments.
POTENTIAL APPLICATIONS:
• CAR- T cell therapy
• Improved blood cancer treatment
ADVANTAGES:
• Increased specificity of CAR-T cell therapy
• Reduce off-target cytotoxic effects of current CAR-T cell therapy
• Improved inhibitory kinetics of iCAR therapy
DEVELOPMENT-TO-DATE:
This technology has been shown to be successful in a laboratory setting where the dual-signaling iCAR constructs showed a reduced delay in the inhibition of cytotoxicity.
Related Papers (from the inventors only):
Bangayan, N. J., Wang, L., Sojo, G. B., Noguchi, M., Cheng, D., Ta, L., Gunn, D., Mao, Z., Liu, S., Yin, Q., Riedinger, M., Li, K., Wu, A. M., Stoyanova, T., & Witte, O. N. (2023). Dual-inhibitory domain iCARs improve the efficiency of the AND-NOT gate CAR T strategy. Proceedings of the National Academy of Sciences of the United States of America, 120(47). https://doi.org/10.1073/pnas.2312374120