Early Prediction of Response to Tyrosine Kinase Inhibitors by Quantification of EGFR Mutations in Plasma of NSCLC Patients. Issue 10 (October 2015)

• Record Type: Journal Article
• Authors: Marchetti, Antonio; Palma, John F.; Felicioni, Lara; De Pas, Tommaso M.; Chiari, Rita; Del Grammastro, Maela; Filice, Giampaolo; Ludovini, Vienna; Brandes, Alba A.; Chella, Antonio; Malorgio, Francesco; Guglielmi, Flavio; De Tursi, Michele; Santoro, Armando; Crinò, Lucio; Buttitta, Fiamma
• Is Part Of: Journal of thoracic oncology. Volume 10:Issue 10(2015)
• Publication Date: 2015-10
• Subjects: Chest -- Cancer -- Periodicals; Thoracic Neoplasms -- Periodicals; 616.99494005
• DOI: 10.1097/JTO.0000000000000643
• Languages: English
• ISSNs: 1556-0864

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Introduction:</title> <p>The potential to accurately quantify epidermal growth factor receptor (<italic>EGFR</italic>) mutations in plasma from non–small-cell lung cancer patients would enable more rapid and more frequent analyses to assess disease status; however, the utility of such analyses for clinical purposes has only recently started to explore.</p> </sec> <sec> <title>Methods:</title> <p>Plasma samples were obtained from 69 patients with <italic>EGFR</italic>-mutated tumors and 21 negative control cases. <italic>EGFR</italic> mutations in plasma were analyzed by a standardized allele-specific polymerase chain reaction (PCR) test and ultra-deep next-generation sequencing (NGS). A semiquantitative index (SQI) was derived from dilutions of known <italic>EGFR</italic> mutation copy numbers. Clinical responses were evaluated by Response Evaluation Criteria in Solid Tumors 1.1 criteria and expressed as percent tumor shrinkage.</p> </sec> <sec> <title>Results:</title> <p>The sensitivity and specificity of the PCR test and NGS assay in plasma versus tissue were 72% versus 100% and 74% versus 100%, respectively. Quantitative indices by the PCR test and NGS were significantly correlated (<italic>p</italic> < 0.001). <italic>EGFR</italic> testing at baseline and serially at 4 to 60 days during tyrosine kinase inhibitor therapy revealed a progressive decrease in SQI, starting from day 4, in 95% of cases. The rate of SQI decrease correlated with percent tumor shrinkage at 2 months (<italic>p</italic> < 0.0001); at 14 days, it was more than 50% in 70% of patients (rapid responders). In two patients with slow response, an early increase in the circulating levels of the T790M mutation was observed. No early T790M mutations were seen in plasma samples of rapid responders.</p> </sec> <sec> <title>Conclusions:</title> <p>Quantification of <italic>EGFR</italic> mutations from plasma with a standardized PCR test is feasible. To our knowledge, this is the first study showing a strong correlation between the <italic>EGFR</italic> SQI in the first days of treatment and clinical response with relevant implications for patient management.</p> </sec> </abstract>