Novel CAR-T cell designs to address the challenges of solid tumor therapy

Abstract

Solid tumors comprise approximately 90% of adult cancers and 30% of childhood cancers [1]. Although treating solid tumors remains disappointingly elusive, the potential of cell-based therapeutics surpasses other modalities suggesting a path forward using cell-based therapies. First, the successful development and fine tuning of Chimeric Antigen Receptors (CARs) are presented to illustrate how highly optimized CARs can be developed de novo. Using the well-characterized HLA-A*02/HPV-E626-38 complex as an example, several novel CARs were created. Following iterative on-target screening and extensive counter-screening, the CARs made from these scFvs displayed sensitivity and selectivity roughly on par with high-performing patient-derived T-cell receptors (TCRs). Next, in vitro comparisons—antigen sensitivity, selectivity, influence of co-stimulation, checkpoint control, cytokine sensitivity, and antigen-dependent exhaustion—of CARs to clinically relevant TCRs across 5 pMHC targets were conducted, suggesting minimal differences between the two receptor classes as potential therapeutics and that the engineered-T cell modality offers a broad design space for innovation. Two clinically relevant applications are then highlighted in the final chapters. First, improved selectivity was engineered in CARs targeting MAGE-A3—well known both as a highly attractive cancer target and for a clinical history marked by severe off-target toxicity as a T-cell therapeutic. In the final chapter, a dual-receptor system is used to create logic gates, enabling modified T cells to selectively target tumor cells with loss of heterozygosity (LOH) while sparing normal cells. As discrimination between tumor and normal cells remains the fundamental challenge in cancer therapy, this system leverages the ability of cells to execute complex behaviors through multivariate signal integration to showcase how the cellular modality unlocks novel target classes to selectively target tumors. Strategies like those detailed here illustrate the potential to engineer T-cell therapies to directly address the challenges posed by solid tumors.

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Christopher Scott (Supervisor) & Jim Johnston (Supervisor)