Performance of a prognostic genomic signature for early-stage NSCLC in matched fresh frozen and RNA-stabilized tissue.

Abstract

7532 Background: Recent clinical studies have demonstrated the benefit of adjuvant chemotherapy (ACT) in some early-stage non-small cell lung cancer (NSCLC) patients. A 15-gene signature, developed using fresh frozen (FF) tissue, has been shown to be an independent prognostic marker that identifies high risk patients who may benefit from ACT. Use of this signature in tissue preserved in an RNA stabilization reagent is desired for easier access to tumor tissue in the clinical setting. Methods: Matched FF and RNAlater-preserved (RNAL) tissues were obtained from 43 NSCLC patients. Patients provided written consent for the collection of tumor tissue at the time of surgery under an IRB approved protocol. Each tissue sample was split into 2 pieces, creating biological replicates for each tissue format. For each patient, RNA was extracted from 4 tissue pieces (2 FF, 2 RNAL), followed by microarray-based genomic profiling (Affymetrix U133 Plus 2.0). The 15-gene signature was applied to each profile, generating a numerical risk score and a risk category (high, low) using methods previously established (Zhu 2010 J Clin Oncol). The level of agreement was evaluated within biological replicates of each tissue format, as well as between the averaged biological replicates of matched FF and RNAL tissues. Results: The concordance in risk category between averaged biological replicates of matched FF and RNAL tissues was 84%, with a Pearson correlation of 0.74. This level of agreement is comparable to the inherent reproducibility of the assay observed within biological replicates of FF tissue, which demonstrated concordance of 79% and Pearson correlation of 0.83. In addition, a statistical in silico simulation was used to demonstrate that if the risk scores in this study had spanned the full dynamic range of the assay while maintaining the same level of inherent reproducibility observed in the current study, the level of concordance would be 89% with a Pearson correlation of 0.93. Conclusions: The level of agreement between matched FF and RNAL tissues is not inferior to that seen within FF biological replicates. Therefore, the 15-gene signature maintains its performance when used in RNAlater-preserved NSCLC tissues.