3D Microphysiological Tumor Model for Dual-Targeting CAR T Cell Immunotherapy

The efficiency of immunotherapy stays limited for solid tumors. It is mainly caused by the tumoral structural heterogeneity and its complex microenvironment, which impede the infiltration of immune cells into malignant tissues. Mimicking this environment in frames of microphysiological models remains a challenge, significantly increasing costs of the clinical translation for the new therapies. Here, we study a 3D multi-spheroid model incorporating prostate stem cell antigen (PSCA) modified PC3 human prostate cancer cells and fibroblast activation protein (FAP) expressing fibrosarcoma HT1080 cells embedded within the soft hydrogel microbeads. We use this model to trial the immunotherapy based on the universal chimeric antigen receptor (UniCAR) T cells, and to better understand the impact of FAP on the immunotherapeutic treatment of solid tumors. First, we demonstrate the successful chemoattraction and infiltration of UniCAR T cells into the area of solid tumors, as well as the ability of UniCAR T cells to navigate through artificial extracellular matrix barriers. We further observe the synergistic efficacy of a dual-targeting UniCAR T cell approach against FAP and PSCA antigens, which represent the tumor microenvironment and the tumor, respectively. The results of our studies offer valuable methodologies and insights for engineering different 3D tumor models and studying immunotargeting of small-sized solid tumors (e.g., metastases and residual tumors). The developed microphysiological system has great potential to advance cancer research efforts aiming to elucidate the pivotal role of microenvironment in solid tumor development, enabling therapy trials and more precise prognosis for patients.