Luan, Q.; Rahnama, A.; Pulido, I.; Raspini, M.; Zhou, J.; Shimamura, T.; Papautsky, I.

Tumor models that recapitulate 3D architecture are essential for understanding how cellular organization and microenvironmental interactions govern therapeutic response in human cancers. Here, we developed a microfluidic microphysiological system that enables controlled and scalable culture and drug testing of non-small cell lung cancer spheroids and patient-derived organoids. The platform integrated U-shaped microwells with dual-channel loading to support de novo spheroid formation, efficient trapping of pre-formed spheroids, and loading of intact organoids with reduced size heterogeneity. Tumor spheroids and organoids maintained high viability and structural integrity during long-term on-chip culture, and constrained microscale confinement produced ellipsoidal geometries that deviate from idealized spherical assumptions. Baseline genotype-dependent responses to KRAS G12C and EGFR inhibitors were preserved across agarose and microfluidic formats, establishing a validated reference state. Building on this baseline, fibroblast- and endothelial-derived cues consistently attenuated responses to targeted therapies across conditioned media, mixed co-culture, and spatially organized configurations. Resistance phenotypes converged on a dominant role for paracrine signaling, while increasing architectural complexity primarily enhanced morphological fidelity rather than altering therapeutic response. These findings establish a microphysiological framework that decouples tumor-intrinsic drug sensitivity from microenvironment-mediated modulation, enabling the systematic evaluation of paracrine resistance mechanisms in NSCLC.