Development and interlaboratory evaluation of a NIST Reference Material RM 8366 for EGFR and MET gene copy number measurements

Background: The National Institute of Standards and Technology (NIST) Reference Material RM 8366 was developed to improve the quality of gene copy measurements of EGFR (epidermal growth factor receptor) and MET (protooncogene, receptor tyrosine kinase), important targets for cancer diagnostics and treatment. The reference material is composed of genomic DNA prepared from six human cancer cell lines with different levels of amplification of the target genes. Methods: The reference values for the ratios of the EGFR and MET gene copy numbers to the copy numbers of reference genes were measured using digital PCR. The digital PCR measurements were confirmed by two additional laboratories. The samples were also characterized using Next Generation Sequencing (NGS) methods including whole genome sequencing (WGS) at three levels of coverage (approximately 1x, 5x and greater than 30x), whole exome sequencing (WES), and two different pan-cancer gene panels. The WES data were analyzed using three different bioinformatic algorithms. Results: The certified values (digital PCR) for EGFR and MET were in good agreement (within 20%) with the values obtained from the different NGS methods and algorithms for five of the six components; one component had lower NGS values. Conclusions: This study shows that NIST RM 8366 is a valuable reference material to evaluate the performance of assays that assess EGFR and MET gene copy number measurements.