The amplification of the gene for HER2 occurs in approximately 20 to 25% of breast cancers. The accurate measurement of this biomarker is important for the proper treatment with anti-HER2 therapeutics. Clinical laboratories are beginning to utilize accurate and sensitive diagnostic tests based on measurements of DNA. We have prepared genomic DNA from 5 human breast cancer cell lines with different amounts of amplification of the HER2 gene. The copy numbers of the HER2 gene and 3 reference genes (not amplified) were measured using quantitative PCR and digital PCR assays. The certified values of the components are the ratios of the HER2 gene copy number to the reference gene copy numbers. The PCR assays were validated and calibrated using NIST SRM® 2372 component A (human genomic DNA). The stability of the components was shown by repeated measurements over several years. The DNA concentration determined from absorbance and the PCR assays was provided as informational value.
SRM® 2373 is currently available and can be obtained from the NIST SRM site http://www.nist.gov/srm/.