Modeling CAR T Cell Trafficking and Efficacy in Solid Tumors Using a Tumor–Vasculature-on-Chip

A Tumor-on-a-Chip Model

Solid tumors remain a major challenge for CAR T cell therapy due to limited infiltration, heterogeneous antigen expression, and therapy-induced toxicity. To study how CAR T cells reach and engage solid tumors, MIMETAS scientists developed an on-chip model to evaluate CAR T cell migration and killing capacity. ECM-embedded colorectal cancer (CRC) cells were incorporated into a model comprising endothelium and T cells. CAR T cells were perfused through the human endothelial vessel adjacent to ECM-embedded tumor cells (Figure 1).

CAR T Cell Trafficking to Tumor Compartment

CAR T cells were perfused through a human endothelial vessel adjacent to ECM-embedded tumor cells, enabling assessment of vascular adhesion, transendothelial migration, and tumor infiltration. CAR T cell infiltration increased over time and was strongly enhanced by a CXCL12 chemokine gradient, indicating active and directed migration (Figure 2A).  CAR T cells infiltrated both target and non-target tumor cell compartments. Quantitative analysis revealed distinct infiltration dynamics between these conditions, with differences in the fraction of CAR T cells entering the tumor compartment over time (Figure 2B). These results demonstrate that CAR T cell trafficking is influenced by tumor context and is not solely determined by target recognition.

Solid Tumor Killing by CAR T Cells

The colon organoid tubules recapitulate multiple essential epithelial functions. Upon exposure to vitamin D₃, gut cells show strong upregulation of CYP3A4, resulting in increased metabolic activity (Figure 3A). In addition, correct cellular polarisation and reporter expression enable highly reliable and physiologically relevant compound transport across the gut barrier (Figure 3B).

Killing Efficacy of CAR T cells depends on Dosing

CAR T cell efficacy in solid tumors was strongly dependent on dosing. By varying the ratio of CAR T cells to tumor cells, the model captured clear dose–response relationships in tumor killing over time. Lower CAR T cell doses resulted in partial growth suppression of antigen-expressing tumor cells, whereas higher doses led to pronounced and sustained tumor clearance (Figure 4A).

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Time-resolved imaging revealed progressive tumor cell loss with increasing CAR T cell dose, while quantitative analysis confirmed a strong, dose-dependent reduction in tumor area over 72 hours. These results demonstrate how the tumor–vasculature-on-chip model enables precise evaluation of CAR T cell dosing effects within a human-relevant 3D tumor microenvironment (Figure 4B).