Farnesyltransferase inhibition overcomes the adaptive resistance to targeted therapies in oncogene-addicted non-small cell lung cancer II

Drug-tolerance has emerged as one of the major non-genetic adaptive processes driving resistance to targeted therapy (TT) in non-small cell lung cancer (NSCLC). However, the kinetics and sequence of molecular events governing this adaptive response remain poorly understood. Here, we performed transcriptomic profiling by RNAseq in a panel of EGFR-mutant NSCLC cell lines (PC9, HCC4006, H3255 and HCC827) that were previously subcloned to minimize the presence of potential pre-existing resistant cells. Cells were treated by either erlotinib (1 µM) or osimertinib (1 µM) for a short period (24h), until drug-tolerance (between 7 and 21 days), and until development of fully resistant proliferative cells (RPC). Overall design: EGFR-mutant NSCLC PC9, HCC4006, H3255 and HCC827 cell lines were subcloned and amplified in drug-free RPMI (Roswell Park Memorial Institute) 1640 medium containing 10% fetal bovine serum (FBS) and were maintained at 37°C in a humidified chamber containing 5% CO2. PC9, HCC4006 and H3255 subclones were treated with DMSO (control) or with erlotinib at 1 µM for 24h, until drug-tolerance (7-to-21 days) or until development of fully resistant proliferative cells (RPC, only for PC9 and HCC4006 cells). RPC were isolated and amplified from individual early-emerging colonies, which were cultured and passaged for more than three months in the presence of the drug. HCC827 were treated with DMSO (control) or with osimertinib at 1 µM until drug-tolerance (11 days).