Denaturing fixatives are compatible with the NanoString nCounter® platform and the Prosigna® assay

We found that RNA yield and purity (A260/A280) were not significantly different between the fixatives within the analysis set. In the analysis of ROR score, the tissue pairs had a Pearson Correlation Coefficient of 0.91, similar to the correlation observed between paired tissue blocks using a single fixative in previous studies. Subtype concordance between differentially fixed tissue pairs was high (K = 0.80). No significant bias or variability in risk of recurrence (ROR) score attributable to fixative was detected in this study. Further analysis revealed that sample pairs with larger differences in ROR score were limited to nearly-depleted tissue blocks containing large amounts of normal tissue due to proximity of the tumor margin. The results of this study demonstrate that the fixative, AFA, does not contribute significantly to bias and variability of assay results.