방사선의학 웹진

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Abstract
Purpose: (4S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid (18F-FSPG) is a radiopharmaceutical for PET imaging of system xC - activity, which can be upregulated in prostate cancer. We present data on the first evaluation of patients with newly diagnosed or recurrent prostate cancer with this radiopharmaceutical.

Experimental design: Ten patients with primary and 10 patients with recurrent prostate cancer were enrolled in this prospective multicenter study. After injection of 300 MBq of 18F-FSPG, three whole-body PET/CT scans were obtained. Visual analysis was compared with step-section histopathology when available as well as other imaging studies and clinical outcomes. Metabolic parameters were measured semiquantitatively. Expression levels of xCT and CD44 were evaluated by IHC for patients with available tissue samples.

Results: 18F-FSPG PET showed high tumor-to-background ratios with a relatively high tumor detection rate on a per-patient (89%) and per-lobe (87%) basis. The sensitivity was slightly higher with imaging at 105 minutes in comparison with 60 minutes. The maximum standardized uptake values (SUVmax) for cancer was significantly higher than both normal (P < 0.005) and benign pathology (P = 0.011), while there was no significant difference between normal and benign pathology (P = 0.120). In the setting of recurrence, agreement with standard imaging was demonstrated in 7 of 9 patients (78%) and 13 of 18 lesions (72%), and revealed true local recurrence in a discordant case. 18F-FSPG accumulation showed moderate correlation with CD44 expression.

Conclusions: 18F-FSPG is a promising tumor imaging agent for PET that seems to have favorable biodistribution and high cancer detection rate in patients with prostate cancer. Further studies are warranted to determine the diagnostic value for both initial staging and recurrence, and how it compares with other investigational radiotracers and conventional imaging modalities.

Affiliations

Sonya Youngju Park #  1   2 , Sae Jung Na #  1   3 , Meena Kumar  2 , Camila Mosci  2 , Mirwais Wardak  2 , Norman Koglin  4 , Santiago Bullich  5 , Andre Mueller  4 , Mathias Berndt  4 , Andrew W Stephens  4 , Yong Mee Cho  6 , Hanjong Ahn  7 , Sun Young Chae  3 , Hye Ok Kim  3   8 , Dae Hyuk Moon  3 , Sanjiv S Gambhir  2   9 , Erik S Mittra  10   11
1 Department of Radiology, College of Medicine, The Catholic University of Korea, Seocho-gu, Seoul, Republic of Korea (South).
2 Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, Stanford, California.
3 Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea (South).
4 Bayer Pharma AG, Berlin, Germany.
5 Life Molecular Imaging GmbH, Berlin, Germany.
6 Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea (South).
7 Department of Urology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea (South).
8 Department of Nuclear Medicine, Ewha Woman's University College of Medicine, Seodaemun-gu, Seoul, Republic of Korea (South).
9 Department of Bioengineering, Department of Materials Science & Engineering, Stanford Bio-X Program, Stanford University, Stanford, California.
10 Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, Stanford, California. mittra@ohsu.edu.
11 Department of Diagnostic Radiology, Oregon Health & Science University, Portland, Oregon.