Siebinga Hinke, Heuvel Judith Olde, Rijkhorst Erik-Jan, Hendrikx Jeroen J M A, de Wit-van der Veen Berlinda J
Department of Nuclear Medicine, Netherlands Cancer Institute, Amsterdam, The Netherlands.
Department of Pharmacy and Pharmacology, Netherlands Cancer Institute, Amsterdam, The Netherlands; and.
J Nucl Med. 2023 Jan;64(1):63-68. doi: 10.2967/jnumed.122.264101. Epub 2022 Jun 9.
Ga-labeled prostate-specific membrane antigen (PSMA) is often produced on-site, where usually a fixed amount of peptide is conjugated to the generator eluate. However, fluctuations in specific activity might influence tracer distribution and tumor accumulation. Therefore, our aim was to investigate the potential effect of varying the administered peptide amount on Ga-PSMA-11 uptake in tumors using PET/CT in patients with primary prostate cancer (PCa). Additionally, the impact of tumor volume on this potential effect and on accumulation in reference organs was assessed. The imaging data of 362 men with primary PCa who underwent Ga-PSMA-11 PET/CT were retrospectively included. Scans were quantified for normal tissue and primary tumors. Patients were divided into 3 groups based on their tumor volume. Correlation and multivariable linear regression analyses were performed. The median index lesion volume was 9.50 cm (range, 0.064-174 cm). Groups were based on quartiles of prostatic lesion volume: ≤4.11 cm (group 1), 4.11-20.6 cm (group 2), and ≥20.6 cm (group 3). No correlation was found between administered peptide amount and tumor uptake (SUV or SUV) for any group, except for a significant correlation for SUV in the first group ( = 0.008). Linear regression analysis supported these findings. The amount of administered peptide had no evident effect on Ga-PSMA-11 uptake in tumors, except for a significant positive correlation between administered peptide amount and tumor SUV for group 1. The findings imply that no receptor saturation occurs in men with primary PCa at peptide levels of about 2.5 μg.
镓标记的前列腺特异性膜抗原（PSMA）通常在现场制备，通常是将固定量的肽与发生器洗脱液偶联。然而，比活度的波动可能会影响示踪剂分布和肿瘤摄取。因此，我们的目的是使用PET/CT研究改变给药肽量对原发性前列腺癌（PCa）患者肿瘤中镓-PSMA-11摄取的潜在影响。此外，评估了肿瘤体积对这种潜在影响以及对参考器官摄取的影响。回顾性纳入了362例接受镓-PSMA-11 PET/CT检查的原发性PCa男性患者的影像数据。对正常组织和原发性肿瘤的扫描进行定量分析。根据肿瘤体积将患者分为3组。进行了相关性和多变量线性回归分析。中位指数病变体积为9.50 cm（范围为0.064 - 174 cm）。分组基于前列腺病变体积的四分位数：≤4.11 cm（第1组），4.11 - 20.6 cm（第2组），≥20.6 cm（第3组）。除第1组SUV存在显著相关性（P = 0.008）外，任何组的给药肽量与肿瘤摄取（SUV或SUV）之间均未发现相关性。线性回归分析支持了这些结果。给药肽量对肿瘤中镓-PSMA-11摄取没有明显影响，除了第1组给药肽量与肿瘤SUV之间存在显著正相关。这些发现表明，在肽水平约为2.5μg时，原发性PCa男性患者不存在受体饱和现象。
