Improved identification of patients with oligometastatic clear cell renal cell carcinoma with PSMA-targeted 18F-DCFPyL PET/CT

Abstract

Objective: Complete surgical resection of metastatic sites has been shown to prolong survival in select patients with oligometastatic RCC. This treatment strategy is dependent upon the accurate characterization of a patient's extent of disease. The objective of this study was to explore the utility of PSMA-targeted 18F-DCFPyL PET/CT in patients with presumed oligometastatic clear cell RCC.

Methods: This is a subset analysis of a prospective study in which patients with RCC were imaged with 18F-DCFPyL PET/CT (ClinicalTrials.gov identifier NCT02687139). In the present analysis, patients with oligometastatic clear cell RCC, defined as ≤ 3 metastatic lesions on conventional imaging, were evaluated. 18F-DCFPyL PET/CT scans were reviewed for sites of disease and compared to conventional imaging.

Results: The final cohort included 14 patients with oligometastatic clear cell RCC. Conventional imaging revealed 21 metastatic lesions and 3 primary tumors. 18F-DCFPyL PET/CT detected 29 sites of metastatic disease and 3 primary tumors. Of the 21 metastatic lesions detected on conventional imaging, 17 (81.0%) had radiotracer uptake. Additionally, all 3 primary tumors had radiotracer uptake. In 4 (28.6%) patients a total of 12 more lesions were identified on 18F-DCFPyL PET/CT than conventional imaging. Notably, 3 (21.4%) patients were no longer considered oligometastatic. The detection rates of conventional imaging and 18F-DCFPyL PET/CT for identifying sites of disease were 66.7% and 88.9%, respectively.

Conclusions: PSMA-targeted PET/CT appears to aid in the identification of patients with oligometastatic clear cell RCC. If borne out in future studies, this suggests that PSMA-targeted imaging has the potential to help select candidates for metastasis-directed therapy.

Keywords: Clear cell; Oligometastatic; PSMA; Renal cell carcinoma.

Conflict of interest statement

Compliance with ethical standards

Conflict of interest MGP is a co-inventor on a US Patent covering 18F-DCFPyL and as such is entitled to a portion of any licensing fees and royalties generated by this technology. This arrangement has been reviewed and approved by the Johns Hopkins University in accordance with its conflict-of-interest policies. MAG has served as a consultant to Progenics Pharmaceuticals, the licensee of 18F-DCFPyL. SPR, MAG, and MGP have received research support from Progenics Pharmaceuticals.

Figures

Fig. 1

Images of a patient with oligometastatic clear cell RCC confirmed with 18F-DCFPyL PET/CT (Patient #12). a Whole-body 18F-DCFPyL PET maximum intensity projection image demonstrates a solitary site of abnormal uptake (red arrowhead) in the region of the left nephrectomy bed. b Axial, contrast-enhanced, venous-phase CT image demonstrates a recurrence in the left nephrectomy bed with tumor invading and expanding the left renal vein (red arrowhead). c Axial 18F-DCFPyL PET and d axial 18F-DCFPyL PET/CT images show focal radiotracer uptake in the lesion (red arrowheads)

Fig. 2

Images of a patient with presumed oligometastatic clear cell RCC found to have additional sites of disease on 18F-DCFPyL PET/CT (Patient #2). a Whole-body 18F-DCFPyL PET maximum intensity projection image demonstrates multiple foci of abnormal radiotracer uptake, some of which are demonstrated in the accompanying panels (red arrowhead, red arrow, and thin red arrow). b Axial, contrast-enhanced, arterial-phase CT image demonstrates subtle arterial enhancement in a small subcarinal lymph node (red arrowhead) that was not initially appreciated prior to PET imaging. c Axial 18F-DCFPyL PET and d axial 18F-DCFPyL PET/CT images show focal radiotracer uptake in the subcarinal lymph node (red arrowheads), strongly suggesting this is a site of metastatic disease. e Axial, contrast-enhanced, arterial-phase CT image demonstrates subtle abnormal enhancement in the neck of the pancreas (red arrow) that was also not appreciated prior to PET imaging. f Axial 18F-DCFPyL PET and g axial 18F-DCFPyL PET/CT images confirm radiotracer uptake at the same site in the pancreas (red arrows), most compatible with this representing an additional site of metastatic disease. h Axial, contrast-enhanced, arterial-phase CT image showing an enhancing nodule in the right paracolic gutter (thin red arrow), compatible with a site of metastatic disease and the original finding that had prompted PET imaging. At the time of the CT, this was thought to be the only site of disease. i Axial 18F-DCFPyL PET and j axial 18F-DCFPyL PET/CT images demonstrate focal radiotracer uptake in the right paracolic gutter lesion (thin red arrows)