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. The microengineered solid tumor models with vascularized tumor explants were infused with CAR T cells and analyzed using single cell RNA-sequencing.