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MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent
Published on: September 3, 2013
Prostate cancer imaging of FSHR antagonist modified with a hydrophilic linker
Chen Zhu1, Qing Xu1, Donghui Pan2
1Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China.
Abstract:
Follicle-stimulating hormone receptor (FSHR) is selectively expressed in endothelial cells of prostate cancer (PCa) and becomes a potential target for tumor diagnosis and therapy. (18)F-Al-NOTA-MAL-FSH1 is a promising PET imaging probe for targeting FSHR; however, the unfavorable abdominal backgrounds may hamper clinical translation. GGGRDN is a new hydrophilic linker, which can improve the imaging quality of radiolabeled peptides. In this study, GGGRDN-FSH1 (denoted as FSH2) was designed and conjugated with NOTA-MAL for (18)F-Al radiolabeling. NOTA-MAL-FSH2 was obtained with about 50% yield and labeled using (18)F-Al in a one-step method within 20 min with a yield of 41.46 ± 10.36% (non-decay-corrected). The radiochemical purity was more than 95% and the specific activity was more than 50 GBq/µmol. The in vitro stability studies were determined in PBS and human serum. (18)F-Al-NOTA-MAL-FSH2 remained stable in PBS and human serum. Balb/c nude mice bearing PC-3 human PCa were used for in vivo study. PC-3 tumors were clearly visualized with good contrast to background through microPET. ROI analysis showed the tumor uptake values were 2.68 ± 0.52 and 1.97 ± 0.61%ID/g at 30 and 60 min post injection (p.i.), respectively. Biodistribution studies showed that the accumulations of (18)F-Al-NOTA-MAL-FSH2 in liver and intestine were 0.47 ± 0.11 and 0.12 ± 0.03%ID/g respectively at 60 min p.i. FSHR-binding specificity was also demonstrated by reduced tumor uptake after coinjection of excessive unlabeled FSH2. In conclusion, (18)F-Al-NOTA-MAL-FSH2 was successfully prepared in a one-step method and showed better pharmacokinetics than (18) F-Al-NOTA-MAL-FSH1. Favorable preclinical study revealed that (18)F-Al-NOTA-MAL-FSH2 appears to be a promising candidate for FSHR-positive tumor imaging.
Insights
A new PET imaging probe, (18)F-Al-NOTA-MAL-FSH2, targets Follicle-stimulating hormone receptor (FSHR) in prostate cancer. This improved probe shows clear tumor visualization and better pharmacokinetics for enhanced cancer diagnosis and therapy.
Area of Science:
- Biomedical imaging
- Radiochemistry
- Oncology
Background:
- Follicle-stimulating hormone receptor (FSHR) is a promising target for prostate cancer (PCa) diagnosis and therapy due to its selective expression in PCa endothelial cells.
- Existing PET imaging probes like (18)F-Al-NOTA-MAL-FSH1 face challenges with unfavorable abdominal backgrounds, potentially limiting clinical application.
Purpose of the Study:
- To design and evaluate a novel PET imaging probe, (18)F-Al-NOTA-MAL-FSH2, utilizing a hydrophilic linker (GGGRDN) to improve imaging quality for FSHR-positive prostate cancer.
- To assess the radiolabeling efficiency, stability, pharmacokinetic properties, and in vivo performance of the new probe.
Main Methods:
- GGGRDN-FSH1 (FSH2) was synthesized and conjugated with NOTA-MAL for (18)F-Al radiolabeling.
- Radiochemical yield, purity, and specific activity of (18)F-Al-NOTA-MAL-FSH2 were determined.
- In vitro stability was assessed in PBS and human serum.
- In vivo microPET imaging and biodistribution studies were conducted in PC-3 human PCa xenograft-bearing mice.
Main Results:
- (18)F-Al-NOTA-MAL-FSH2 was prepared efficiently in a one-step method with good radiochemical yield (41.46 ± 10.36%) and high purity (>95%).
- The probe demonstrated excellent stability in vitro and favorable pharmacokinetics with clear visualization of PC-3 tumors in vivo.
- Tumor uptake was significant, and biodistribution showed low accumulation in off-target organs like the liver and intestine.
Conclusions:
- (18)F-Al-NOTA-MAL-FSH2 is a successfully developed PET imaging agent for FSHR-positive tumors, prepared via a facile one-step radiolabeling process.
- The probe exhibits improved characteristics compared to previous agents, suggesting its potential as a valuable tool for prostate cancer imaging.
- Further preclinical evaluation supports (18)F-Al-NOTA-MAL-FSH2 as a promising candidate for clinical translation in FSHR-positive tumor detection.
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