Abstract A26: Translation of isoform-level gene signature into robust diagnostic assay for glioblastoma subtyping.

Translating the molecular signatures from classification strategies into robust diagnostic assays is essential for cancer therapy guidance and prognosis determination. To develop a clinically applicable molecular stratification assay for Glioblastoma multiforme (GBM) with significant prognostic value, we designed a novel classification system based on isoform-level gene expression profiles; an avenue unexplored for diagnostic and prognostic use. Using isoform-level expression clustering of The Cancer Genome Atlas (TCGA) samples, we identified four GBM subgroups with significant (p=0.0103) survival differences. A four-class classifier, built with 121 transcript-variants, assigns GBM patients’ molecular subtype with 92% accuracy. The classifier was translated to a high-throughput RT-qPCR assay and validated on an independent cohort of 206 glioblastoma samples. We found that proneural patients have the worst prognosis except for younger patients (<40 years), while a better prognosis is observed for neural group among older patients (≥40 years). The isoform-level classifier, transformed from a high-dimensional platform to a low-dimensional RT-qPCR platform, provides a quantitative and reproducible stratification of GBM patients with prognostic significance, a requirement towards personalized medicine. The resulting diagnostic assay from the classifier has immediate clinical implications towards prioritizing patients for standard care versus aggressive therapy regimen. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A26. Citation Format: Yingtao Bi, Sharmistha Pal, Luke Macyszyn, Louise C. Showe, Donald O'Rourke, Ramana V. Davuluri. Translation of isoform-level gene signature into robust diagnostic assay for glioblastoma subtyping. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A26.