Comprehensive Genomic Profiling of Circulating Cell-Free DNA Distinguishes Focal MET Amplification from Aneuploidy in Diverse Advanced Cancers

• Published in: Current oncology (Toronto) 2021-09, Vol.28 (5), p.3717-3728
• Main Authors: Kumaki, Yuichi, Olsen, Steve, Suenaga, Mitsukuni, Nakagawa, Tsuyoshi, Uetake, Hiroyuki, Ikeda, Sadakatsu
• Format: Article
• Language: English
• Subjects: Aneuploidy; Cell-Free Nucleic Acids - genetics; cfDNA; Circulating Tumor DNA - genetics; ctDNA; focal amplification; Genomics; Humans; liquid biopsies; MET; Neoplasms - diagnosis; Neoplasms - genetics
• ISSN: 1718-7729; 1198-0052; 1718-7729
• DOI: 10.3390/curroncol28050317

Amplification (amp) of can be observed in cases of focal gene copy number gain, such as -driven amp, or with a gain of chromosome 7, such as aneuploidy. Several studies have shown that only high-level focal amp ( /CEP7 ratio ≥5) is oncogenic, with such tumors responding to targeted therapy. However, there are few reports on how to distinguish between focal amplification and aneuploidy using next-generation sequencing (NGS). A total of 1025 patients with advanced solid tumors (typically pre-treated) were tested with a non-invasive comprehensive cfDNA NGS panel (Guardant360) from July 2014 to June 2019. Since bioinformatics upgrades of Guardant360 were undergoing in September 2018, focal amp was determined by our independent algorithm using the cohorts tested before September 2018 (291 patients), and validation was performed in the remaining cohort (734 patients). alterations (alts) associated with aberrant signaling were found in 110 patients (10.7%) among nine different cancer types, most commonly in non-small cell (12.2%, 62/510) and small cell (33.3%, 3/9) lung cancers, gastroesophageal cancer (19.4%, 7/36), and prostate adenocarcinoma (15.6%; 5/32). Among 291 patients tested before September 2018, 37 (12.7%) had alts. Among these, 24 (64.9%) had amps, 5 (13.5%) had exon 14 skipping, and 13 (35.1%) had single nucleotide variants (SNVs). Co-alterations, such as amp + SNVs, were found in four samples (10.8%). Among 24 amps, 29.2% (7/24) were focal according to our algorithm. copy number was significantly higher with focal amp compared to non-focal amp (mean copy number 3.26 vs. 2.44, respectively, = 0.00304). In 734 patients tested after September 2018, our definition of focal amp was detected in 4.2% (31/734). Overall, focal amplification based on our algorithm was 3.7% (=38/1025). This study describes an approach to distinguish focal and non-focal amplification using comprehensive genomic profiling of cfDNA in advanced cancer patients. Focal amp accounted for ~30% of all amp, which was found in 3.7% of patients with diverse cancers and was associated with a higher plasma copy number. Clinical studies are warranted to assess the clinical utility of targeted therapies for tumors with focal amplification detected by NGS of cfDNA.