Development of the First F-Labeled Radiohybrid-Based Minigastrin Derivative with High Target Affinity and Tumor Accumulation by Substitution of the Chelating Moiety.

In order to optimize elevated kidney retention of previously reported minigastrin derivatives, we substituted ()-DOTAGA by DOTA in ()-DOTAGA-rhCCK-16/-18. CCK-2R-mediated internalization and affinity of the new compounds were determined using AR42J cells. Biodistribution and SPECT/CT imaging studies at 1 and 24 h p.

Comparison of Quantification of Target-Specific Accumulation of [F]F-siPSMA-14 in the HET-CAM Model and in Mice Using PET/MRI.

Assessment of biodistribution and specific tumor accumulation is essential for the development of new radiopharmaceuticals and requires animal experiments. The HET-CAM (hens-egg test-chorioallantoic membrane) model can be used in combination with the non-invasive imaging modalities PET and MRI for pre-selection during radiopharmaceutical development to reduce the number of animal experiments required. Critical to the acceptance of this model is the demonstration of the quantifiability and reproducibility of these data compared to the standard animal model.

Automated synthesis of [F]Ga-rhPSMA-7/ -7.3: results, quality control and experience from more than 200 routine productions.

Introduction: The radiohybrid (rh) prostate-specific membrane antigen (PSMA)-targeted ligand [F]Ga-rhPSMA-7 has previously been clinically assessed and demonstrated promising results for PET-imaging of prostate cancer. The ligand is present as a mixture of four stereoisomers ([F]Ga-rhPSMA-7.1, - 7.

Preclinical comparison of four [F, Ga]rhPSMA-7 isomers: influence of the stereoconfiguration on pharmacokinetics.

Introduction: Radiohybrid (rh) ligands, a novel class of prostate-specific membrane antigen (PSMA)-targeted radiopharmaceuticals, can be labeled either with [F]fluorine via isotopic exchange or with radiometals (such as [Ga]Gallium, [Lu]Lutetium, [Ac]Actinium). Among these, [F, Ga]rhPSMA-7 has recently entered clinical assessment.

Aim: Since [F, Ga]rhPSMA-7 is composed of four stereoisomers ([F, Ga]rhPSMA-7.

Radiohybrid Ligands: A Novel Tracer Concept Exemplified by F- or Ga-Labeled rhPSMA Inhibitors.

When we critically assess the reason for the current dominance of Ga-labeled peptides and peptide-like ligands in radiopharmacy and nuclear medicine, we have to conclude that the major advantage of such radiopharmaceuticals is the apparent lack of suitable F-labeling technologies with proven clinical relevance. To prepare and to subsequently perform a clinical proof-of-concept study on the general suitability of silicon-fluoride-acceptor (SiFA)-conjugated radiopharmaceuticals, we developed inhibitors of the prostate-specific membrane antigen (PSMA) that are labeled by isotopic exchange (IE). To compensate for the pronounced lipophilicity of the SiFA unit, we used metal chelates, conjugated in close proximity to SiFA.