Two independent reports introduced vascularized tumor‑on‑chip platforms that model human solid tumors and permit controlled CAR‑T perfusion, visualization, and functional testing. Authors used vascularized lung adenocarcinoma explants and mesothelioma models to show how the tumor microenvironment impedes CAR‑T infiltration, tested chemokine‑directed CAR engineering strategies, and validated pharmacologic targets in matched mouse models. The work, published in Nature Biotechnology and related journals, provides scalable in vitro systems to screen CAR‑T modifications, biomarkers, and combination therapies before clinical testing. Tumor‑on‑chip platforms recreate key microenvironmental features—stroma, vasculature, and metabolites—critical for evaluating cell‑therapy efficacy in solid tumors.