Refining High-Risk EGFR-Mutant Lung Cancer Patients: The Role of Adjusted Variant Allele Frequency in First-Line Osimertinib Therapy.

Next-Generation Sequencing (NGS) has an increasing role in patients with advanced non-small-cell lung cancer (aNSCLC) and, in parallel, the use of targeted therapy dramatically improves the outcome of those with actionable alterations. In this scenario, the possible prognostic significance of some features provided by NGS testing and, among these, of Variant Allele Frequency (VAF), is still unclear. Herein, we report a real-world single-center prospective cohort of 88 consecutive patients with aNSCLC profiled by NGS and harboring a classic EGFR mutation, who were treated with the standard first-line tyrosine kinase inhibitor osimertinib. A subset of patients with shorter progression-free survival (PFS) was characterized by extremely high VAF/tumor cellularity, >1.7 adjusted VAF (aVAF). Median PFS was 5.3 months shorter in the high aVAF cohort; a similar trend was observed in overall survival too. No significant association between aVAF and TP53 mutations, Tumor Mutational Burden or other clinical, pathological or molecular features was found. Our findings suggest that NGS could improve the traditional binary classification of EGFR mutations in aNSCLC, highlighting a correlation between high EGFR mutations aVAF and worse outcome.