Abstract
Human epidermal growth factor receptor 2 (HER2) aberrations are observed in various cancers. In non-small cell lung cancer, genetic alterations activating HER2, mostly exon 20 insertion mutations, occur in approximately 2-4% of cases. Trastuzumab deruxtecan (T-DXd), a HER2-targeted antibody-drug conjugate has been approved as the first HER2-targeted drug for HER2-mutant lung cancer. However, some cases are not responsive to T-DXd and the primary resistant mechanism remains unclear. In this study, we assessed sensitivity to T-DXd in JFCR-007, a patient-derived HER2-mutant lung cancer cell line. Although JFCR-007 was sensitive to HER2 tyrosine kinase inhibitors, it showed resistance to T-DXd in attachment or spheroid conditions. Accordingly, we established a three-dimensional (3D) layered co-culture model of JFCR-007, where it exhibited a lumen-like structure and became sensitive to T-DXd. In addition, an in-house inhibitor library screening revealed that G007-LK, a tankyrase inhibitor, was effective when combined with T-DXd. G007-LK increased the cytotoxicity of topoisomerase-I inhibitor, DXd, a payload of T-DXd and SN-38. This combined effect was also observed in H2170, an HER2-amplified lung cancer cell line. These results suggest that the proposed 3D co-culture system may help in evaluating the efficacy of T-DXd and may recapitulate the tumor microenvironment.