Identification of gamma delta T cell fitness determinants for cancer immunotherapy by their immunoprofiling in patients with immune-mediated diseases

Chimeric Antigen Receptor (CAR)-T cell therapy is a clinically approved cancer immunotherapy approach using genetically engineered T cells. It represents a paradigm shift in the treatment of certain blood cancers that do not respond to other available treatment options. Currently clinically approved CAR-T cells are generated from autologous (patient's own) T cells and focused on αβ T cell subsets. The success of CAR-T cells has been met with challenges regarding efficacy, safety, and broad availability. One approach to address this issue is to use alternative immune cells to generate CAR-T cells. In our research group, we became interested in γδ T cells because of their unique properties, such as their antitumor activity independent of conventional major histocompatibility complex (MHC)-mediated antigen processing, and presentation and the combination of functions characteristic of T cells, NK cells, and antigen-presenting cells. Although γδ T cells have proven to be very attractive effectors for the generation of CAR-T cells for cancer immunotherapy, their efficacy may be limited in some instances. One example is shorter persistence and limited function compared with αβ CAR-T cells that were observed in one model. This led us to hypothesize that intrinsic functions and dysfunctions might be the key factor for the successful γδ CAR-T cell approach. Compared with αβ CAR-T cells, the key determinants that define successful therapeutic outcomes are much less known in γδ CAR-T cells. This problem needs to be addressed to unlock the potential of γδ CAR-T cells as a platform that can act in settings where αβ CAR-T cells have limited activity. The clinical partners on this project observed a large increase in the frequency of γδ T cells in the peripheral blood of certain patients with atopic dermatitis (AD) and inborn errors of immunity (IEI). This unusual finding inspired us to explore the mechanisms leading to the increase in frequency, which could be pathological in the context of AD and IEI but is unique from the perspective of γδ T cell biology. We hypothesize that by studying γδ T cells in this unique patient cohort, we can gain new insights into γδ T cell biology to develop γδ CAR-T cell products with improved functionality and persistence for the treatment of cancer. In addition, this avenue will allow us to investigate the potential links between the pathological manifestation of increased γδ T cell frequency in AD and IEI, which could improve the identification, monitoring, and treatment of these diseases. Our project is divided into three objectives: In the first objective, we will conduct a clinical study in pediatric patients with AD and IEI in whom an increased frequency of γδ T cells is observed. We will develop and validate a comprehensive spectral flow cytometry panel to characterize their immunophenotypes. In the second objective, we will apply this flow cytometry panel to examine circulating immunophenotypes of γδ T cells and identify determinants associated with increased frequency. We will then perform RNA sequencing of isolated γδ T cells to better understand the mechanisms underlying increased frequency. As a third objective, we will evaluate the fitness and function of γδ CAR-T cells generated from patient-derived γδ T cells.