Abstract LB220: Microfluidic devices to decipher the role of the microenvironment in drug resistance

Non-small cell lung carcinoma (NSCLC) is the leading cause of cancer-related deaths worldwide, with adenocarcinoma being the primary histological subtype. Third-generation EGFR tyrosine kinase inhibitor (TKI) osimertinib is the first-line treatment for NSCLC patients with tumors harboring EGFR kinase domain mutations, significantly improving patient survival. However, mechanisms of acquired drug resistance inevitably emerge and must be addressed. While the acquisition of secondary mutations in EGFR, such as C797S mutation, is a known resistance mechanism, non-genetic mechanisms of drug resistance, including vasoconstriction reducing the flow of the blood and the drug to the tumors, have also been observed and are highly significant. We have developed microfluidic devices that support the independent growth of tumor spheroids and patient-derived organoids (PDOs). These platforms feature U-shaped microwells that enable the sustained growth of spheroids for several weeks. This system has proven highly effective for viability assays using small samples including PDOs, suggesting its potential application in personalized medicine assays. More recently, these devices have been employed to evaluate the impact of tumor microenvironment (TME) components, such as endothelial and aortic smooth muscle cells, on drug sensitivity. Indirect co-culture of endothelial HUVEC cells and H6080 aortic smooth muscle cells with various EGFR mutant NSCLC cells promoted EGFR TKI resistance in the epithelial cells, increasing the IC50 by the factor of 10 in H1975 and HCC827. Pharmacodynamic analyses revealed that ERK phosphorylation levels in the presence of supernatants from endothelial and vascular cells, indicating a significant paracrine interaction between TME cells and tumor cells. Notably, this enhanced drug resistance was also observed in KRASG12C H358 mutant cells in response to adagrasib, a KRASG12C inhibitor.Interestingly, this microfluidic device can be optimized to measure relevant chemokines and cytokines secreted by cell lines and PDOs. Characterizing the content and concentrations of various metabolites is particularly important. For example, we have demonstrated that elevated levels of EDN1 promote vasoconstriction leading to drug resistance both in vitro and in vivo. The HCC827, HCC4006 and H1975 EGFR-mutant cell lines show a significant increase in EDN1 mRNA expression and decrease in VEGFA mRNA after 72h of osimertinib treatment. This transcriptional regulation of EDN1 and VEGF-A result in elevated level of EDN1 peptide and depleted VEGF-A in cell lines and EGFR-mutant PDOs including RLUN007. The resulting changes in the peptides promoted vasoconstriction in tumor-feeding vessels and reduced concentration of osimertinib in tumors. These findings underscore the need to develop tools that replicate and mimic the intricate interactions between tumor cells and the TME. Such advancements will enable the use of relevant and limited patient samples to implement personalized medicine approaches and improve patients outcomes. Citation Format: Mohammad Amir Mishan, Ali Rahnama, Ines Pulido Endrino, Laura Gunder, Malek Massad, Khaled Abdelhady, Agustin Lahoz, Ian Papautsky, Takeshi Shimamura. Microfluidic devices to decipher the role of the microenvironment in drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited s); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2): nr LB220.