Abstract 3753: Quantitation of EGFR and phosphoEGFR in FFPE tissue

• Published in: Cancer research (Chicago, Ill.) Ill.), 2010-04, Vol.70 (8_Supplement), p.3753-3753
• Main Authors: Hembrough, Todd, Krizman, David, Heidbrink-Thompson, Jenny, Thyparambil, Sheeno, Burrows, Jon, Darfler, Marlene, Taylor, Paul, Tong, Jiefie, Shi, Warren, Tsao, Ming, Moran, Michael
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM10-3753

The epidermal growth factor receptor (EGFR) is a drug target for both small molecule and antibody therapeutic approaches for several cancers; however, current methods of selecting patients that will most likely respond to anti-EGR therapy are not effective. Better methods for patient stratification are needed. To this end we have developed an approach which can determine both absolute EGFR levels and the phosphorylation status of EGFR directly in formalin-fixed paraffin-embedded (FFPE) patient tissue. This approach is based on the Liquid Tissue®-SRM technology platform, a combination of tissue microdissection, Liquid Tissue® processing which turns dissected tissue to a complete solubilized tryptic digest, and mass spectrometry-based selected reaction monitoring (SRM). This approach was used to measure the EGFR protein and its phosphorylation status in formalin fixed tissue culture cells, xenograft tumors, and patient tumor tissue. For assay development, 3 distinct tryptic peptides were assessed for absolute protein quantitation and multiple peptides where specific residues are known to become phosphorylated (pT693 and pY1197) were assessed for assaying the phosphorylation status of the EGFR protein. We demonstrate the ability to detect and quantify the EGFR protein and to monitor its phosphorylation status directly in patient tumor tissue. This approach offers a dynamic range and quantification which is superior to traditional IHC methods, and that could be used to identify and stratify patients most likely to benefit from anti-EGFR therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3753.