Cell-Free Circulating Tumor DNA Improves Standard Genotyping of Non-Small-Cell Lung Cancer and Increases Detection of Targetable Alterations in a Selected Hispanic Cohort.

ABSTRACT

BACKGROUND: Several studies have shown that the non-small-cell lung cancer (NSCLC) genomic background among Hispanics differs from other populations. The finding of low-frequency genomic alterations in cell-free DNA (cfDNA) can increase diagnostic accuracy and could improve treatment in NSCLC. METHODS: Data from 54 Hispanic patients with advanced NSCLC with high clinical suspicion for ALK, EGFR, and ROS1 mutations were collected (including young age, female sex, and non-smokers). cfDNA was extracted from plasma and analyzed using a commercial next-generation sequencing test (Guardant360) which detects genomic alterations in 74 genes. RESULTS: The median age was 56 years (range 31-83). Most patients were female (661.1%) and never smokers (72.3%). Among the patients included, 96% (52/54) had cfDNA detectable alterations with a mean number of 3.37 cfDNA alterations per test (range 1-10). cfDNA was able to detect some genomic alterations previously undetected by tissue biopsy. Among patients with insufficient or unavailable tissue to perform testing, mutations in EGFR and ALK which led to a change in therapy were determined using cfDNA in 28.8 and 3.8% of cases, respectively. Among patients with cfDNA alterations, 46.1% (n = 24) were switched to a targeted therapy with a median progression-free survival of 11.1 months (95% CI 7.6-14.6) and an overall survival of 40.3 months (95% CI 27.1-53.6). Concurrent genetic mutations with TP53 and KRAS negatively impacted the prognosis. CONCLUSIONS: In a selected population of NSCLC Hispanic patients, comprehensive cfDNA analysis allowed a treatment change in 46.1% of the cases. Guardant360 allows the identification of genomic alterations to improve treatment selection and increase prognosis.