Abstract 1248: The use of nanoimmunoassay technology to predict response to insulin-like growth factor-1 receptor inhibition in head and neck squamous carcinoma
Authors: Khalil Ashraf A. , Allak Amir , Carlson Hans , VanKoevering Kyle , Afere Oluwayemisi , Taniguchi Linnea , Mendez Rolando , Jameson Mark J. 
Published: August 2012

Abstract
Background: Signaling from the insulin-like growth factor-1 receptor (IGF1R) can play a role in resistance to anti-cancer therapy in head and neck squamous cell carcinoma (HNSCC). Thus, targeted inhibition of the IGF1R holds substantial therapeutic potential. However, while several small molecule tyrosine kinase inhibitors (TKIs) of the IGF1R are in clinical trials, there is no definitive biomarker that predicts tumor responsiveness to anti-IGF1R therapy. It is likely that such a predictive biomarker would be a component of the most prominent downstream signaling cascades from the IGF1R, such as the MEK/ERK pathway or the PI3K/AKT pathway. Aims: (1) Identify a short-term predictor of long-term growth inhibition when the IGF1R-TKI OSI-906 is used alone or combined with an EGFR-TKI or cisplatin in HNSCC cell lines. (2) Validate a nanoscale method to quantitate ERK inhibition as a marker of growth inhibition and caspase-3 cleavage as a marker of apoptosis which can ultimately be used in preclinical and clinical studies. Methods: A novel and highly sensitive nanofluidic immunoassay (NIA) that is highly efficient at detecting changes in protein phosphorylation states has recently been developed. This emerging technology uses isoelectric focusing to characterize proteins in extremely small samples such as fine needle aspirate (FNA) biopsies. The utility of NIA was initially tested on Cal27 cells in vitro and studies were subsequently extended to Cal27 xenograft tumors in nude mice. Results: Using the NIA approach, basal and treated levels of unphosphorylated, monophosphorylated, and disphosphorylated ERK1 and ERK2 could be resolved using 40 ng of Cal27 cell lysate. Treatment with 1uM of OSI-906 or gefitinib resulted in 90% reduction in phospho-ERK species; the combination of both drugs completely eliminated ERK phosphorylation. Using the same approach, both drugs were noted to induce caspase-3 cleavage, which was greatest with combination treatment. These data correlate with reduced cell number and increased apoptosis at 24-72 h using standard assays. Preliminary studies using Cal27 xenografts in nude mice demonstrate the ability to detect ERK and caspase-3 in FNA biopsies of the tumors. Conclusion: Using NIA technology, ERK phosphorylation and/or caspase-3 cleavage may have utility as early markers of response when HNSCC cells or tumors are treated with TKIs or other drugs. This approach allows for micro- or nanoscale studies in vitro and simplifies assessment of very small tissue samples. As such, it has the potential to be used as a tool to determine the response of TKIs in patients at the molecular level without waiting for a clinical response.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1248. doi:1538-7445.AM2012-1248