Next-generation Ligand-dependent Transcriptional Switch Receptors for the Control and Customization of Cell Therapeutics

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ABSTRACT Cytokine immunotherapeutics and chimeric antigen receptor-T cells (CAR-Ts) carry great potential for inducing a patient’s own immune system to clear a malignant lesion. Unfortunately, many of these potential immunotherapies are hindered by poor efficacies and unacceptable toxicities, such as “on-target, off-tumor effects”, where healthy tissues become unintended CAR-T targets by expressing tumor antigens at low levels. In contrast to constitutive CAR expression, inducing a T cell to only express an immunotherapeutic in the presence of a second tumor antigen adds additional regulation over the cytotoxic response. A recent development, synthetic Notch (SynNotch) receptor circuits allow for immunotherapeutic expression to be restricted to tumor sites. However, these receptors do not provide control over the amount of expressed immunotherapeutic, nor do they allow for regulation of an output’s half-life. The ability to tune the level and duration of an induced cell-based immunotherapeutic would further improve on the safety of cell-based immunotherapies and provide a platform for robust tuning of an immunotherapeutic regimen. To date in my graduate training, several novel receptor designs that produce distinct levels and half-lives of transcriptional output in response to a surface-expressed antigen have been engineered. Through receptor domain modulation, these receptor scaffolds can prompt the delivery of a set amount of output to a set tissue type, for a set amount of time. In addition, certain novel receptors act as “OR” gates, being activatable by either ligand or T-cell activation. For this proposal, these receptors will be tested for their ability to induce the expression of various potential immunotherapeutics, including CARs and cytokines in human primary T-cells, as measured by ELISA and flow cytometry. In addition, receptors will be tested as part of receptor-CAR positive feedback circuits for their ability to prime CAR-T cells to better clear a heterogenous tumor by inducing a more sustained anti-tumor response, both in cell culture and in mouse model. The University of California, San Francisco (UCSF) is a leading institution in synthetic immunology, and its faculty are well experienced in physician-scientist training. As a MD/PhD student in the Roybal lab at UCSF, I have access to support and collaboration from world-renowned investigators, as well as resources from the Parker Institute for Cancer Immunotherapy and the Chan Zuckerberg BioHub. In addition to my PhD research, my training plan includes medical preceptorships with world-class physicians during my graduate training, additional teaching opportunities through the UCSF School of Medicine, and further clinical training through UCSF resources, including the UCSF Bridges medical curriculum. Overall, this training proposal seeks to further develop synthetic receptor circuits as a tool for improving the safety and efficacy of potential immunotherapies while providing me a diverse set of experiences in preparation for a future career as a physician-scientist.