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DOI: 10.1055/s-0040-1708381
Zr-89-N-sucDf-Amc-2NaI -KuE (Zr-89 PSMA Df) offers a prolonged time frame for prostate cancer imaging with potentially improved tumor detection
Publikationsverlauf
Publikationsdatum:
08. April 2020 (online)
Ziel/Aim Today, the detection of prostate carcinoma lesions by means of PSMA-PET is usually realized in within few hours after injections with the available radiotracers such as e.g. Ga-68 PSMA 11 or F-18-JK-PSMA 7. It cannot be expected that the optimum contrast is achieved within such short time of biodistribution. Therefore, in order to overcome this limitation, we have proposed a new PSMA-binding compound that exploits the longer physical half-life (78 h) of Zr-89: Zr-89 PSMA Df.
Methodik/Methods The precursor was provided by ABX GmbH (Radeberg). The N-sucDF-Fe moiety functionalizes the molecule for labeling with Zr-89. The Zr-89 PSMA Df was characterized in vitro by the calculation of the corresponding Kd value, the cellular uptake and the internalization in LNCaP cells. Its biodistribution in vivo was studied with LNCaP prostate tumor xenograft in mice and PET-imaging experiments were conducted on a Focus 220 micro PET scanner. For reasons of comparison, analogue experiments and compound characterization were carried out with Ga-68 PSMA 11 and F-18 JK-PSMA 7.
Ergebnisse/Results The labelling of Zr-89 PSMA Df was performed in a radiochemical purity ≥ 99.9 %. It showed very high stability in PBS and human serum until 7 d at 37 oC. At 2 h, all radiotracers showed a comparable tumor uptake of approximately 20 % ID/g. Zr-89-PSMA Df allowed the acquisition of small animal PET-images with demarcated tumor after 24 h and 52 h p.i., showing that over time the compound remains in the tumor with very low activity in background except for the kidneys. The analysis of the PET-images also revealed that tumor-to-background ratios are increasing over time.
Schlussfolgerungen/Conclusions This study demonstrates that the tumor uptake and the biodistribution in normal tissues of Zr-89 PSMA Df is comparable to Ga-68 PSMA-11 and F-18 JK-PSMA 7. The small animal PET data suggest that Zr-89 PSMA Df remains in the tumor up to 52 h p.i. with increasing tumor/background ratio. Together with the long half-life of the Zr-89-label, this novel tracer may therefore allow late PET-acquisition with improved lesion detection.
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