11069 Background: Recent advances in biologically directed therapies for non-small cell lung carcinoma (NSCLC) emphasize the need for more accurate sub-classification of NSCLC, as treatment may be dictated by histologic subtype. In particular, squamous histology can be a counter-indication for treatment by VEGF inhibitors. MicroRNAs are highly tissue-specific biomarkers with potential clinical applicability for defining cancer type and origin. MicroRNAs are well preserved in formalin fixed tissue, making them ideal candidates for molecular markers for use in routinely processed material. Here we report on the development and performance of a microRNA-based assay for the differential diagnosis of squamous from non-squamous NSCLC. Methods: We developed protocols for extraction of high-quality RNA that retain the microRNA fraction from FFPE archival tissue samples. MicroRNA microarrays were used to profile more than a hundred NSCLC samples. Specific microRNA qRT-PCR was used to validate results, and to develop a diagnostic assay. Results: We identified a microRNA biomarker that is strongly overexpressed in squamous cell NSCLC. A diagnostic assay (miRview squamous) was developed, that utilizes qRT-PCR measurement of this microRNA, normalized by an additional microRNA and a small nuclear RNA. This assay was validated on a blinded test set of 64 tumor samples, and had sensitivity of 97% and specificity of 91%. More than ¾ of the samples were classified with high confidence, and these classifications were accurate in 96% of the cases. Conclusions: MicroRNAs are becoming an important tool for classification of cancers. A diagnostic assay based on the specificity of a single microRNA accurately identifies squamous from non-squamous NSCLC. This assay provides an important new tool for the classification of NSCLC. [Table: see text]
New molecular classification of large cell neuroendocrine carcinoma and small cell lung carcinoma with potential therapeutic impacts