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[Objectives] Resistance to tyrosine-kinase inhibitors (TKIs) is a clinical challenge in patients with oncogene-driven non-small-cell lung cancers (NSCLC). We have analyzed the utility of next-generation sequencing (NGS) of cell-free circulating tumor DNA (ctDNA) to impact the clinical care of patients with TKI resistance., [Materials and methods] We conducted a multi-institutional prospective study including consecutive EGFR, ALK, or ROS1-altered NSCLC patients with TKI resistance from 12 Spanish institutions. Post-progression ctDNA NGS was performed by Guardant Health (Guardant360 assay)., [Results] We included 53 patients separated in 3 cohorts: 31 EGFR-mutant NSCLCs with first/second-generation TKI resistance (cohort 1), 15 EGFR T790M + NSCLCs with osimertinib resistance (cohort 2), and 7 ALK/ROS1-rearranged NSCLCs with crizotinib and/or next-generation TKI resistance (cohort 3). Besides Guardant360, 22 patients from cohort 1 (71%) underwent post-progression tumor biopsies and/or alternative plasma-based genotyping. In the entire study population, 34 patients (64%) had reliable evidence of tumor-DNA shed for resistance assessment, and 24 patients (45%) had actionable alterations. Target-independent pathogenic alterations were frequently detected, particularly at osimertinib resistance. Eleven patients (20%) received subsequent molecular-guided therapies indicated by plasma NGS alone (n = 9, 17%), or plasma NGS and tissue sequencing (n = 2, 4%), deriving the expected clinical benefit. Of these, 9 had EGFR T790 M mutation and received osimertinib, 1 had ALK G1202R mutation and received lorlatinib, and 1 had ROS1 G2032R mutation and received cabozantinib. Two additional cases from cohort 1 (6%) had undetectable EGFR T790 M by Guardant360 but were T790M + by tissue and BEAMing digital PCR respectively, and also received osimertinib., [Conclusion] NGS of ctDNA detects actionable alterations in a large proportion of oncogene-driven NSCLC patients with TKI resistance, and can be used to guide subsequent treatments as a complement or alternative to tissue or PCR-based plasma genotyping in the real-world clinical setting.

[Background] Approximately 30% of tumor biopsies from patients with advanced-stage lung adenocarcinomas yield insufficient tissue for successful molecular subtyping. We have analyzed the clinical utility of next-generation sequencing (NGS) of cell-free circulating tumor DNA (ctDNA) in patients with inadequate tumor samples for tissue genotyping. [Patients and methods] We conducted the study in a multi-institutional prospective cohort of clinically unselected patients with advanced-stage lung adenocarcinomas with insufficient tissue for EGFR, ALK or ROS1 genotyping across 12 Spanish institutions (n = 93). ctDNA NGS was carried out by Guardant Health (Guardant360, Redwood City, CA), using a hybrid-capture-based 73-gene panel. Variants were deemed actionable if they were part of the OncoKB precision oncology knowledge database and classified in four levels of actionability based on their clinical or preclinical evidence for drug response. [Results] Eighty-three out of 93 patients (89%) had detectable levels of ctDNA. Potentially actionable level 1–4 genomic alterations were detected in 53 cases (57%), of which 13 (14%) had level 1–2A alterations (Food and Drug Administration-approved and standard-care biomarkers according to lung cancer guidelines). Frequencies of each genomic alteration in ctDNA were consistent with those observed in unselected pulmonary adenocarcinomas. The majority of the patients (62%), particularly those with actionable alterations (87%), had more than one pathogenic variant in ctDNA. The median turnaround time to genomic results was 13 days. Twelve patients (13%) received genotype-matched therapies based on ctDNA results, deriving the expected clinical benefit. Patients with co-occurring pathogenic alterations had a significantly shorter median overall survival as compared with patients without co-occurring pathogenic alteration (multivariate hazard ratio = 5.35, P = 0.01). [Conclusion] Digital NGS of ctDNA in lung cancers with insufficient tumor