In this phase I study, we evaluated the safety, biodistribution and dosimetry of [Zr]Zr-DFO-girentuximab (Zr-girentuximab) PET/CT imaging in patients with suspicion of clear cell renal cell carcinoma (ccRCC).
Ten eligible patients received an intravenous administration of 37 MBq (± 10%) of Zr-girentuximab at mass doses of 5 mg or 10 mg. Safety was evaluated according to the NCI CTCAE (version 4.03). Biodistribution and normal organ dosimetry was performed based on PET/CT images acquired at 0.5, 4, 24, 72 and 168 h post-administration. Additionally, tumour dosimetry was performed in patients with confirmed ccRCC and visible tumour uptake on PET/CT imaging.
Zr-girentuximab was administered in ten patients as per protocol. No treatment-related adverse events ≥ grade 3 were reported. Zr-girentuximab imaging allowed successful differentiation between ccRCC and non-ccRCC lesions in all patients, as confirmed with histological data. Dosimetry analysis using OLINDA/EXM 2.1 showed that the organs receiving the highest doses (mean ± SD) were the liver (1.86 ± 0.40 mGy/MBq), the kidneys (1.50 ± 0.22 mGy/MBq) and the heart wall (1.45 ± 0.19 mGy/MBq), with a mean whole body effective dose of 0.57 ± 0.08 mSv/MBq. Tumour dosimetry was performed in the 6 patients with histologically confirmed ccRCC resulting in a median tumour-absorbed dose of 4.03 mGy/MBq (range 1.90-11.6 mGy/MBq).
This study demonstrates that Zr-girentuximab is safe and well tolerated for the administered activities and mass doses and allows quantitative assessment of Zr-girentuximab PET/CT imaging in patients with suspicion of ccRCC.
NCT03556046-14th of June, 2018.

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