Engineered yeast cells simulating CD19+ cancers to control CAR T cell activation

Abstract

Chimeric antigen receptor (CAR) T cells have become an established form of immunotherapy and continue to show promising results for the treatment of hematological cancers in most patients. While this immunotherapy continues to generate excitement in the clinic, antigen modulation in cancer cells affects the quality and safety of CAR T cell therapy. Here we present the engineering of yeast to robustly and dynamically modulate antigen densities, hence establishing a novel tool for assessing antigen-density thresholds in CAR T cell responses. Using a synthetic biology approach, we successfully engineer yeast to simulate cancer cells and demonstrate i) controllable antigen densities of CD19 through the use of G protein-coupled receptors (GPCRs), ii) a customizable system for tuning antigen densities through the employment of heterologous GPCRs for defining signal input types and signal pathway engineering for adapting intensities, and iii) activational control of clinically-derived CAR T cells within a physiologically relevant range compared to the activation elicited by a NALM6 cancer cell line. Based on this yeast-based antigen-presenting cell system, we envision an efficient assessment of how varying antigen densities in cancer cells from patients affect CAR T cell responses and ultimately support safer and better quality of personalized cancer therapies.

Engineered yeast multicellularity via synthetic cell-cell adhesion and direct-contact signalling

“…Although engineered cell contact-based signalling has been widely demonstrated in mammalian cell systems, it has not been exploited for use in yeast, despite yeast being important for high-throughput research in investigating biological mechanisms and for drug development 15,16 . In past work, yeast surface display technologies have been used to establish cell contact-based signalling associations directly between yeast and mammalian cells to explore immune-related protein interactions 17,18 . However, a juxtacrine-like signalling system that works exclusively between yeast cells has not been described and could offer significant value for increasing the complexity of synthetic biology, especially if used in engineered populations of yeast cells that can have been designed to specifically bind to one another.…”