Cell-based therapeutics have become a powerful method to combat cancer. Unlike small-molecule drugs or biologics, cells are able to integrate multiple inputs to execute complex response behaviors. Although cell-based therapies are poised to revolutionize cancer treatment, the field is still in its infancy in that it is still risky and often ineffective at treating most cancers. This dissertation focuses on applying the principles and tools of synthetic biology in T cells to develop the next generation of engineered T cells that will lead to more reliable, safe, and effective therapeutics.
In order for engineered T cells to safely and reliably eradicate solid tumors, we need to generate T cells that are targeted specifically enough to prevent on-target, off-tumor toxicities but flexible enough to overcome the heterogeneous antigen expression patterns. To accomplish this, we developed a two-receptor system (a “prime-and-kill” circuit) that is capable of integrating information across multiple cells such that the T cells can target and kill tumor cells without damaging normal cells. We have demonstrated in vitro and in vivo that the prime-and-kill circuit is capable of eradicating tumors while sparing the normal tissues for which they may have had on-target, off-tumor toxicity.
Another limitation for CAR T cell therapy is dependence on endogenous T cell circuitry to activate T cells to kill tumor cells. Due to such dependence, it has been difficult to control the level of T cell cytotoxic response. One approach to overcome this limitation is to enable T cells to have customizable input/output functions independent of endogenous T cell signaling. We developed a new chimeric force sensing receptor (A2-Notch receptor) to allow better tuning and control of the input/output function. By engineering the T cells to tune the levels of immune response through the A2-Notch receptor, T cells may be able to overcome the immunosuppressive blockade without causing unwanted side effects.
The next wave of T cell therapies will need to be programmed to autonomously regulate sensing and response behaviors. These studies demonstrate the utility of using synthetic biology principles to facilitate T cell activity in order to generate safer and effective cell-based therapies.