Abstract 61: Use of two-color fluorometric real-time PCR to develop molecular diagnostic tests with intrinsic quality control that augment cytomorphologic diagnosis of lung cancer.

Abstract

Quantitative RT-PCR tests that measure transcript abundance of selected genes in clinical specimens promise to improve cancer diagnostic accuracy and enable “personalized medicine” through selection of the most effective treatment for each cancer. However, most clinical samples are Formalin-Fixed, Paraffin-Embedded (FFPE) and these yield sub-optimal RNA integrity. Thus, there is a need for qPCR tests with increased robustness that also have intrinsic quality control and low cost. To address this need, we developed qPCR methods that enable simultaneous measurement of each target gene and reference gene transcript relative to a known number of gene-specific internal standard (IS) molecules using two-color fluorometric analysis on real-time platform. For each gene, a competitive template IS was synthesized containing 4-6 nucleotide changes relative to the native template (NT). During PCR, NT or IS signal was quantified with sequence-specific FAM-labeled probe or Quasar 670-labeled probe, respectively. To optimize measurement sensitivity for analysis of highly degraded FFPE samples; a) each RNA sample was reverse transcribed (RT) with gene-specific primer and b) cDNA was pre-amplified with 18 PCR cycles in the presence of internal standards. Results obtained with pre-amp or no pre-amp conditions were highly correspondent. We conducted a validation study of this assay in 38 samples (10 malignant and 10 benign surgical FFPE tissues and 13 malignant and 5 benign fine needle aspirate (FNA) samples. Consistent with previous results in fresh frozen surgical samples, the lung cancer diagnostic test (LCDT) optimal cut-off value discriminated malignant from non-malignant tissues (p = 0.0009), had 92.9% specificity and 75.0% sensitivity, and a receiver operator characteristic area under the curve of 0.87 (95% confidence interval 0.74-0.99). Based on these data, we expect that this quality-controlled two color fluorometric qPCR approach will enable reliable analysis of the LCDT and other promising qPCR-based molecular diagnostic tests in small degraded RNA extracted from clinical FFPE and FNA cell block FFPE samples. Citation Format: Jiyoun Yeo, Erin L. Crawford, Thomas M. Blomquist, Lauren M. Stanoszek, Rachel E. Dannemiller, Laura Jordan, Jill Zyrek, Luis de la Casas, James C. Willey. Use of two-color fluorometric real-time PCR to develop molecular diagnostic tests with intrinsic quality control that augment cytomorphologic diagnosis of lung cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 61. doi:10.1158/1538-7445.AM2013-61