Targeted DNA and RNA sequencing of paired urothelial and squamous bladder cancers to reveal discordant genomic and transcriptomic events and unique therapeutic opportunities.

Authors

null

Daniel H. Hovelson

University of Michigan Department of Computational Medicine and Bioinformatics, Ann Arbor, MI

Daniel H. Hovelson , Lorena Lazo De La Vega , Andrew McDaniel , Aaron Udager , Rohit Mehra , Ganesh S. Palapattu , Alon Z. Weizer , Todd Matthew Morgan , Jeffrey Scott Montgomery , Scott A. Tomlins

Organizations

University of Michigan Department of Computational Medicine and Bioinformatics, Ann Arbor, MI, University of Michigan, Ann Arbor, MI, Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, University of Michigan Medical School, Ann Arbor, MI

Research Funding

NIH

Background: Expression-based molecular subtypes thought to be intrinsic in bladder cancer have been widely reported, carrying important potential clinical treatment implications. Histologically, bladder cancers are also heterogeneous diseases, with a large portion of urothelial carcinomas exhibiting divergent differentiation. Previous subtyping efforts have been carried out using predominantly fresh frozen tissue samples, potentially obscuring this known differentiation heterogeneity. Methods: Here we performed targeted multiplexed, amplicon-based DNA and RNA sequencing on 100 formalin-fixed paraffin-embedded (FFPE) bladder cancer samples (including 12 paired urothelial / squamous lesions). High-confidence somatic point mutations, short insertions/deletions (indels), and copy number alterations were detected using the DNA component of the Oncomine Comprehensive Assay (OCP). Targeted RNA sequencing was carried out using a custom Ampliseq panel comprised of 8 housekeeping genes and 103 target genes assessing major transcriptional programs as identified from publically available data. Results: By DNA analysis, we observe frequent TP53 (35%) and activating hotspot PIK3CA (23%) somatic mutations across the cohort, as well as targetable high-level (log-2 copy number ratio > = 1.5) focal amplifications of ERBB2 (3%) or EGFR (3%) in a subset of samples. We report a novel approach for detecting sub-gene copy-number alterations, and confirm several detectable multi-exon losses using whole transcriptome RNA sequencing. Pairing targeted RNA expression analysis with DNA-based alterations, we show high level expression of EGFR and ERBB2 in focally-amplified samples. Most importantly, we show that despite identical prioritized somatic genomic alterations, we observe divergent expression-based profiles in 3 of 12 (25%) paired urothelial and squamous samples. Conclusions: Taken together, these results highlight the importance of molecular heterogeneity in bladder cancer and suggest important considerations for using existing expression-based clustering approaches to guide clinical treatment decisions.

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Abstract Details

Meeting

2017 Genitourinary Cancers Symposium

Session Type

Poster Session

Session Title

Poster Session B: Prostate Cancer and Urothelial Carcinoma

Track

Prostate Cancer,Urothelial Carcinoma,Prostate Cancer

Sub Track

Urothelial Carcinoma

Citation

J Clin Oncol 35, 2017 (suppl 6S; abstract 296)

DOI

10.1200/JCO.2017.35.6_suppl.296

Abstract #

296

Poster Bd #

E9

Abstract Disclosures

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