Positron emission tomography/computed tomography identification of clear cell renal cell carcinoma: results from the REDECT trial

Abstract

Purpose: A clinical study to characterize renal masses with positron emission tomography/computed tomography (PET/CT) was undertaken.

Patients and methods: This was an open-label multicenter study of iodine-124 ((124)I) -girentuximab PET/CT in patients with renal masses who were scheduled for resection. PET/CT and contrast-enhanced CT (CECT) of the abdomen were performed 2 to 6 days after intravenous (124)I-girentuximab administration and before resection of the renal mass(es). Images were interpreted centrally by three blinded readers for each imaging modality. Tumor histology was determined by a blinded central pathologist. The primary end points-average sensitivity and specificity for clear cell renal cell carcinoma (ccRCC)-were compared between the two modalities. Agreement between and within readers was assessed.

Results: (124)I-girentuximab was well tolerated. In all, 195 patients had complete data sets (histopathologic diagnosis and PET/CT and CECT results) available. The average sensitivity was 86.2% (95% CI, 75.3% to 97.1%) for PET/CT and 75.5% (95% CI, 62.6% to 88.4%) for CECT (P = .023). The average specificity was 85.9% (95% CI, 69.4% to 99.9%) for PET/CT and 46.8% (95% CI, 18.8% to 74.7%) for CECT (P = .005). Inter-reader agreement was high (κ range, 0.87 to 0.92 for PET/CT; 0.67 to 0.76 for CECT), as was intrareader agreement (range, 87% to 100% for PET/CT; 73.7% to 91.3% for CECT).

Conclusion: This study represents (to the best of our knowledge) the first clinical validation of a molecular imaging biomarker for malignancy. (124)I-girentuximab PET/CT can accurately and noninvasively identify ccRCC, with potential utility for designing best management approaches for patients with renal masses.

Trial registration: ClinicalTrials.gov NCT00606632.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

Patient flow diagram. ccRCC, clear cell renal cell carcinoma; CECT, contrast-enhanced computed tomography; IP, investigational product; PET/CT, positron emission tomography/computed tomography.

Fig 2.

Patient with a 1.0-cm right renal clear cell carcinoma. (A) The mass is evident in the noncontrast computed tomography (CT) component of the positron emission tomography/computed tomography (PET/CT) scans, (B) is positive on the iodine-124 (124I) -girentuximab PET component, and (C) is clearly evident on the fused image. The mass was deemed to be positive on the contrast-enhanced CT scan of the (D) parenchymal component and (E) excretory component by Hounsfield criteria and qualitatively.

Fig 3.

Patient with a 1.8-cm right renal oncocytoma. The mass was deemed to be positive for clear cell renal cell carcinoma on the contrast-enhanced computed tomography scan of the (A) parenchymal component and (B) excretory component by Hounsfield criteria and qualitatively. (C) The iodine-124 (124I) -girentuximab positron emission tomography/computed tomography scan is negative.