[932] Diagnostic Value of ERG Oncoprotein Detection in Biopsy Specimens.

Daniel Russell, George L Lee, Patrick Parker, Bungo Furusato, Denise Y Young, Yongmei Chen, Taduru Sreenath, Albert Dobi, David G Mcleod, Shiv Srivastava, Isabell A Sesterhenn, Joel T Moncur. Department of Surgery, Uniformed Services University of the Health Sciences, Rockville, MD; Armed Forces Institute of Pathology, Washington, DC; Walter Reed Army Medical Center, Washington, DC

Background: In the last 10 to 15 years, the increasing need for diagnostic precision has led to the introduction of biochemical markers, such as α-Methylacyl coenzyme A racemase (AMACR), 34βE12, and p63 to support the diagnosis of prostate cancer. However, these markers are not without shortcomings. In recent years, TMPRSS2-ERG genomic fusion has been demonstrated in 40 to 80% of prostate cancers. We have developed a monoclonal anti-ERG antibody (ERG-MAb, clone 9F4) that demonstrated an unprecedented 99.9% specificity in detecting the protein product of the recurrent TMPRSS2-ERG fusions. Previously we have shown that when AMACR and ERG expression were examined together, 96.4% of patients with prostate cancer were positive for at least one of the two genes. The hypothesis of this study was that diagnostic accuracy can be improved by adding ERG to AMACR immunohistochemical (IHC) staining in prostate biopsy specimens.
Design: In a retrospective set of 88 patients undergoing prostate biopsies, prostate cancer was identified in 44 patients. 10 of these patients subsequently underwent radical prostatectomy. The 385 slides from the 88 biopsy sets were evaluated by IHC with 350 stained with ERG-MAb only and 35 stained for both ERG-MAb and AMACR.
Results: AMACR was detected in 28 of 31 and ERG in 37 of 70 of tumor positive biopsies. Of the three biopsies with benign tissue only, one was positive for AMACR. However, in six other biopsies, both tumor and benign tissue were positive for AMACR. ERG was detected only in 0.4% (1/280) of benign glands total. Of the three slides with AMACR negative tumors, two were positive for ERG.
Conclusions: Our findings highlight that the highly specific detection of ERG oncoprotein, a product of the TMPRSS2-ERG gene fusion, when combined with AMACR improves the diagnostic specificity in prostate biopsy specimens.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 1:00 PM

Poster Session II # 108, Monday Afternoon


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