The prostate-specific membrane antigen (PSMA)-targeted radiotracer 18F-DCFPyL detects tumor neovasculature in metastatic, advanced, radioiodine-refractory, differentiated thyroid cancer.

Abstract

Prostate-specific membrane antigen (PSMA; also termed glutamate carboxypeptidase II (GCP II)) is abundantly expressed in prostate cancer. It has been shown recently that PSMA is expressed in neovasculature of differentiated thyroid cancer. In this study, we show that 18F-DCFPyl might detect neovasculature in advanced, metastatic differentiated thyroid cancer (DTC). We first stained the preserved lymph node samples of three patients with DTC who had undergone total thyroidectomy and neck dissection for cervical lymph node metastatic disease to identify PSMA expression, with the PSMA antibody (DAKO Monoclonal). Then, we performed 18F-DCFPyl imaging in two other advanced DTC patients with elevated serum thyroglobulin (Tg), indicative of residual disease. We compared the findings with contemporaneous FDG PET/CT scan, conventional Imaging (CT,MRI) and whole-body scan performed with I123/I131. All the three lymph node samples stained positive for PSMA expression in the neovasculature. In the first imaged patient, 18F-DCFPyl detected activity within the retropharyngeal CT contrast-enhancing lymph node. Compared to FDG PET/CT, the 18F-DCFPyl scan showed a greater SUV (3.1 vs 1.8). In the second imaged patient, 18F-DCFPyl showed intense uptake in the L3 vertebra (not seen on the post treatment 131I scan or the 18F-FDG PET/CT). MRI of the lumbar spine confirmed the presence of sclerotic-lytic lesion at the location, consistent with metastatic disease. Our exploratory study is proof of principle, that the prostate cancer imaging agent 18F-DCFPyl may prove useful for the localization of metastases, in patients with metastatic RAI-refractory DTC by detecting neoangiogenesis within the tumor.

• Authors: Prasanna Santhanam, Jonathon Russell, Lisa M Rooper, Paul W Ladenson, Martin G Pomper, Steven P Rowe
• Journal: Medical oncology (Northwood, London, England) (Med Oncol) Vol. 37 Issue 11 Pg. 98 (Oct 09 2020) ISSN: 1559-131X [Electronic] United States
• PMID: 33034761 (Publication Type: Journal Article)

Chemical References

• Antigens, Surface
• Fluorine Radioisotopes
• Iodine Radioisotopes
• Radiopharmaceuticals
• Fluorodeoxyglucose F18
• FOLH1 protein, human
• Glutamate Carboxypeptidase II

Topics

• Adult
• Antigens, Surface (metabolism)
• Drug Resistance, Neoplasm
• Fluorine Radioisotopes (metabolism, therapeutic use)
• Fluorodeoxyglucose F18 (metabolism, therapeutic use)
• Glutamate Carboxypeptidase II (metabolism)
• Humans
• Iodine Radioisotopes (metabolism, therapeutic use)
• Male
• Middle Aged
• Neoplasm, Residual
• Neovascularization, Pathologic (diagnostic imaging, metabolism, pathology)
• Positron Emission Tomography Computed Tomography
• Radiopharmaceuticals (metabolism, therapeutic use)
• Thyroid Neoplasms (diagnostic imaging, metabolism, pathology)
• Whole Body Imaging