AbstractBackgroundThe standard of care in newly diagnosed metastatic non‐small cell lung cancer (NSCLC) is to test for aberrations in three genes for driver mutations – ALK, ROS1 and epidermal growth factor receptor (EGFR) – and also for immunohistochemistry to be performed for programmed death‐ligand 1 expression level. Next‐generation sequencing (NGS), with or without RNA fusion testing, is increasingly used in standard clinical practice to identify patients with potentially actionable mutations. Stratification of NGS mutation tiers is currently based on the European Society of Medical Oncology Scale for Clinical Actionability of Molecular Targets (ESCAT) Tiers I–V and X.AimOur aim was to analyse NSCLC tumour samples for the prevalence of Tiers I–V mutations to establish guidance for current and novel treatments in patients with metastatic disease.MethodsNGS was performed employing the Oncomine Precision Assay (without RNA fusion testing) that interrogates DNA hotspot variants across 45 genes to screen 210 NSCLC tissue samples obtained across six Sydney hospitals between June 2021 and March 2022.ResultsIn our cohort, 161 of 210 (77%) had at least one gene mutation identified, with 41 of 210 (20%) having two or more concurrent mutations. Tier I mutations included 42 of 210 (20%) EGFR mutations (EIA) and five of 210 (3%) MET exon 14 skipping mutations (EIB). Non‐Tier I variants included 22 of 210 (11%) KRAS G12C hotspot mutations (EIIB), with a further 47 of 210 (22%) having non‐G12C KRAS (EX) mutations. NGS testing revealed an additional 15% of cases with Tier II ESCAT mutations in NSCLC. Forty‐six percent of patients also demonstrated potential Tier III and IV mutations that are currently under investigation in early‐phase clinical trials.ConclusionsIn addition to identifying patients with genomic alterations suitable for clinically proven standard‐of‐care therapeutic options, the 45‐gene NGS panel has significant potential in identifying potentially actionable non‐Tier 1 mutations that may become future standard clinical practice in NSCLC.