Acquired resistance of EGFR-mutant lung adenocarcinomas to afatinib plus cetuximab is associated with activation of mTORC1. Homo sapiens

Patients with EGFR-mutant lung adenocarcinomas who initially respond to first-generation TKIs develop resistance to these drugs. A combination of the irreversible TKI afatinib and the EGFR antibody cetuximab can be used to overcome resistance to first-generation TKIs; however, resistance to this drug combination eventually emerges. We used xenografts and genetically engineered mouse models (GEMMs) to model acquired resistance in lung adenocarcinomas. We identified enhanced activation of the mTORC1 signaling pathway as a mechanism of resistance to dual inhibition of EGFR in mouse models. Addition of rapamycin reversed resistance in vivo. Analysis of afatinib+cetuximab-resistant biopsy specimens revealed the presence of genomic alterations in genes that modulate mTORC1 signaling including NF2 and TSC1. These findings pinpoint enhanced mTORC1 activation as a mechanism of resistance to afatinib+cetuximab and identify genomic mechanisms that lead to activation of this pathway revealing a potential therapeutic strategy for treating patients with resistance to these drugs.