Triplet therapy overcomes 3rd-EGFR TKI-resistant EGFR-L858R/T790M/C797S in trans and in cis/L718Q mutation

Cancer is a dynamic disease. During the course of disease, cancers generally become more heterogeneous. As a result of this heterogeneity, the bulk tumour might include a diverse collection of cells harbouring distinct molecular signatures with differential levels of sensitivity to treatment. This heterogeneity might result in a non-uniform distribution of genetically distinct tumour-cell subpopulations across and within disease sites (spatial heterogeneity) or temporal variations in the molecular makeup of cancer cells (temporal heterogeneity). Heterogeneity provides the fuel for resistance; therefore, an accurate assessment of tumour heterogeneity is essential for the development of effective therapies. Multiregion sequencing, single-cell sequencing, analysis of autopsy samples, and longitudinal analysis of liquid biopsy samples are all emerging technologies with considerable potential to dissect the complex clonal architecture of cancers. In this Review, we discuss the driving forces behind intratumoural heterogeneity and the current approaches used to combat this heterogeneity and its consequences. We also explore how clinical assessments of tumour heterogeneity might facilitate the development of more-effective personalized therapies. Show more

Alflutinib (AST2818) is a newly developed third-generation EGFR tyrosine kinase inhibitor selective for EGFR-sensitizing and T790M-resistant mutations. We assessed the safety, efficacy, and pharmacokinetics of alflutinib in patients with advanced NSCLC with confirmed EGFR T790M mutation, whose status progressed after the first- or second-generation EGFR tyrosine kinase inhibitor therapy. Show more

Osimertinib, a mutant-specific third generation EGFR TKI, is emerging as the preferred first-line therapy for EGFR mutant lung cancer, yet resistance inevitably develops in patients. We modeled acquired resistance to osimertinib in transgenic mouse models of EGFR L858R -induced lung adenocarcinoma and found that it is mediated largely through secondary mutations in EGFR – either C797S or L718V/Q. Analysis of circulating free DNA data from patients revealed that L718Q/V mutations almost always occur in the context of an L858R driver mutation. Therapeutic testing in mice revealed that both erlotinib and afatinib caused regression of osimertinib-resistant C797S-containing tumors, whereas only afatinib was effective on L718Q mutant tumors. Combination first-line osimertinib plus erlotinib treatment prevented the emergence of secondary mutations in EGFR . These findings highlight how knowledge of the specific characteristics of resistance mutations are important for determining potential subsequent treatment approaches and suggest strategies to overcome or prevent osimertinib resistance in vivo. Show more