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

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 used the FUCCI (fluorescence ubiquitination cell cycle indicator) system to perform real-time monitoring of the cell cycle dynamics the EGFR-mutant NSCLC cell line HCC4006, which was previously subcloned to minimize the presence of potential pre-existing resistant cells. We performed scRNAseq on G1 (red) and S/G2 (green) cells sorted from untreated (DMSO), osimertinib-treated and osimertinib+tipifarnib-treated cells to identify molecular mechanisms implicated in the adaptive response to TT and the sensitivity of drug-tolerant cells to tipifarnib. Overall design: FUCCI-transduced HCC4006 subcloned cells were expanded in untreated (DMSO), osimertinib (1 µM) or osimertinib (1 µM) + tipifarnib (1 µM)-containing medium for 4, 20 and 12 days respectively. Drug-containing medium was changed 24h before sorting. Cells were dissociated by trypsinisation, recovered in FACS buffer (0,04% BSA in PBS) and kept on ice. G1 (red) and S/G2 (green) cells were sorted at 4°C using FACS Melody (BD Biosciences).