68Ga-P16-093 Diagnostic Performance in Newly Diagnosed Prostate Cancer- Histopathologic Correlation

(UroToday.com) The 2024 Society of Nuclear Medicine & Molecular Imaging (SNMMI) annual meeting featured a session on prostate cancer, and a presentation by Dr. Jiarou Wang discussing the diagnostic performance of ⁶⁸Ga-P16-093 in newly diagnosed prostate cancer. ⁶⁸Ga-P16-093 is a novel PSMA-targeted radiopharmaceutical that has a labeling reaction compatible with various Ge/Ga generators and has a simple labeling method of heating at 95 degrees Celsius for 5 minutes, leading to high radiochemical purity. As a targeting agent in prostate cancer patients, ⁶⁸Ga-P16-093 has the following compared to ⁶⁸Ga-PSMA:

• Higher tumor uptake
• Better lesion detection
• Faster blood clearance with lower bladder accumulation
• Higher tumor-to-blood pool ratio 

Additionally, it has been surmised that ⁶⁸Ga-P16-093 has higher sensitivity for extraprostatic extension, allowing increased nerve sparing during robotic prostatectomy without increasing positive margins. Thus, the aim of this study was to investigate the diagnostic performance of ⁶⁸Ga-P16-093 in newly diagnosed prostate cancer compared with ⁶⁸Ga-PSMA-11 dynamic contrast material–enhanced MR imaging, with pathology as the reference standard.

 There were 50 biopsy-proven prostate cancer patients enrolled in this prospective study. Each patient underwent ⁶⁸Ga-P16-093 and ⁶⁸Ga-PSMA-11 PET/CT within a week. Thirty of the patients also underwent dynamic contrast material–enhanced MR imaging. According to the anatomical position, the prostate sample was divided into 30 sections. Furthermore, using the same positioning coordinates, Dr. Wang and colleagues also divided the PET imaging and MR imaging of the prostate into 30 sections. PET imaging, MR images and pathological findings were evaluated independently and blindl and then correlated with pathological findings. The following image is of a 66-year-old patient with biopsy positive regions in 2, 4, 5, and 11 (A). ⁶⁸Ga-P16-093 PET/CT exhibited high PSMA uptake in the right peripheral zone of the prostate, with an SUV_max of 9.1 (B). Pathologic examination confirmed the presence of prostate cancer in the right peripheral zone, consistent with the ⁶⁸Ga-P16-093 PET/CT findings (C):

The intensity of two tracer accumulations was measured by SUV_max for semiquantitative comparison and image consistency analysis.

Based on segment-to-segment comparison with pathological reference standard, the sensitivity, and specificity of ⁶⁸Ga-P16-093 PET/CT was 0.944 (95% CI 0.935–0.995), and 0.950 (95% CI 0.943–0.975), while the sensitivity and specificity of ⁶⁸Ga-PSMA-11 PET/CT was 0.801 (95% CI 0.780–0.959), and 0.939 (95% CI:0.910–0.959), and the sensitivity and specificity of MRI was 0.77 (95% CI 0.67–0.78), and 0.90 (95% CI: 0.85–0.93). The ROC analysis showed that the AUC for ⁶⁸Ga-P16-093 PET/CT predicted true positive and false positive lesions significantly higher than ⁶⁸Ga-PSMA-11 PET/CT and dynamic contrast material–enhanced MR imaging. Ultimately, ⁶⁸Ga-P16-093 PET/CT showed good diagnostic performance and demonstrated superiority in local diagnosis.

 ⁶⁸Ga-P16-093 PET/CT SUV_max was also correlated with Gleason score (biopsy pathology slides) (r = 0.395, p = 0.002), Gleason score (surgical pathology slides) (r = 0.642, p 68Ga-PSMA-11 SUV_max (r = 0.945, p 68Ga-P16-093 PET/CT was correlated with immunohistochemistry of PSMA expression in all 50 patients:
Dr. Wang concluded this presentation discussing the diagnostic performance of ⁶⁸Ga-P16-093 in newly diagnosed prostate cancer with the following take-home messages:

• Head-to-head ⁶⁸Ga-P16-093 versus ⁶⁸Ga-PSMA-11 PET/CT images analyzed from a local segmentation perspective, using pathology as a gold standard
• The results demonstrated high sensitivity and specificity
• The correlation with surgical pathology Gleason scores was strong, providing a more accurate reflection of the local lesion severity
• The correlation with PSMA immunohistochemical staining scores on pathological slices was significant, providing new evidence for biopsy localization and guidance for local treatment
• ⁶⁸Ga-P16-093 is a useful PSMA targeting agent for prostate cancer

Presented by: Jiarou Wang, Peking Union Medical College Hospital, Beijing, China

Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 Society of Nuclear Medicine & Molecular Imaging (SNMMI) Annual Meeting, Toronto, Ontario, Canada, Sat, June 8 – Tues, June 11, 2024.