Low levels of PSMA expression limit the utility of 18 F-DCFPyL PET/CT for imaging urothelial carcinoma
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SHORT COMMUNICATION
Low levels of PSMA expression limit the utility of 18F-DCFPyL PET/CT for imaging urothelial carcinoma Scott P. Campbell1 · Alexander S. Baras2 · Mark W. Ball1 · Max Kates1 · Noah M. Hahn3 · Trinity J. Bivalacqua1,3 · Michael H. Johnson1 · Martin G. Pomper1,3,4 · Mohamad E. Allaf1,3 · Steven P. Rowe1,4 · Michael A. Gorin1,2,3,4,5
Received: 18 October 2017 / Accepted: 18 October 2017 © The Japanese Society of Nuclear Medicine 2017
Abstract Objective To explore the clinical utility of PSMA-targeted 18 F-DCFPyL PET/CT in patients with metastatic urothelial carcinoma. Methods Three patients with metastatic urothelial carcinoma were imaged with 18F-DCFPyL PET/CT. All lesions with perceptible radiotracer uptake above background were considered positive. Maximum standardized uptake values were recorded for each detected lesion and findings on 18F-DCFPyL PET/CT were compared to those on conventional imaging studies. To further explore PSMA as a molecular target of urothelial carcinoma, RNA-sequencing data from The Cancer Genome Atlas were used to compare the relative expression of PSMA among cases of bladder cancer, prostate cancer, and clear cell renal cell carcinoma. Additionally, immunohistochemical staining for PSMA was performed on a biopsy specimen from one of the imaged patients.
* Michael A. Gorin [email protected] 1
The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
2
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
3
Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
4
The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
5
600 North Wolfe Street, Park 213, Baltimore, MD 21287, USA
Results 18F-DCFPyL PET/CT allowed for the detection of sites of urothelial carcinoma, albeit with low levels of radiotracer uptake. Analysis of RNA-sequencing data revealed that bladder cancer had significantly lower levels of PSMA expression than both prostate cancer and clear cell renal cell carcinoma. Consistent with this observation, immunohistochemical staining of tissue from one of the imaged patients demonstrated a low level of neovascularization and nearly absent PSMA expression. Conclusion The relatively scant expression of PSMA by urothelial carcinoma likely limits the utility of PSMAtargeted PET imaging of this malignancy. Future research efforts should focus on the development of other molecularly targeted imaging agents for urothelial carcinoma. Keywords Prostate-specific membrane antigen · PSMA · F-DCFPyL PET/CT · Urothelial carcinoma · Bladder cancer · Transitional cell carcinoma
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Introduction At the present time, the mainstays of imaging for urothelial carcinoma of bladder and upper urinary tract are computed tomography (CT) and magnetic resonance imaging (MRI) [1]. These imaging
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