Microengineered transplantation of human solid tumors for in vitro studies of CAR T immunotherapy

Despite its proven efficacy for hematologic malignancies, chimeric antigen receptor (CAR) T cell therapy has met with limited success in treating solid tumors. While this represents a significant clinical challenge in cancer immunotherapy, preclinical efforts to assess and improve the efficacy and safety of CAR T therapy are hindered by our limited ability to model, probe, and modulate the complexity of cancer-immune interactions in solid tumors. Here, we present a microengineered platform for in vitro reproduction, real-time imaging, and in-depth analysis of malignant human solid tumors during CAR T therapy. Using a compartmentalized device with an externally accessible interface, this system makes it possible to engineer three-dimensional organotypic constructs composed of human tumor explants that can be vascularized and perfused with blood-borne immune cells in a controlled manner. We first present a microphysiological model of adenocarcinoma tumors in the human lung infused with CAR-T cells to demonstrate its capabilities to reproduce the three essential steps of targeting solid tumors, including CAR T cell recognition of tumor-associated antigens, infiltration, and survival and effector function in the tumor microenvironment. Using flow cytometry and single-cell RNA sequencing, we probe how the phenotype of CAR T cells changes during their recruitment and persistence. Furthermore, we use the sequencing data to discover a therapeutic target that can be pharmacologically inhibited in our model to significantly increase CAR T cell trafficking and their anti-tumor effects, for which we also present specific biomarkers identified by untargeted metabolomics analysis. This work provides a potentially powerful approach for mechanistic studies and preclinical screening of adoptive cell therapies for cancer and other complex diseases. Overall design: The microengineered solid tumor models with vascularized tumor explants were infused with CAR T cells and analyzed using single cell RNA-sequencing.