English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  The AAZTA chelator and in particular its bifunctional derivative AAZTA 5  was recently investigated to demonstrate unique capabilities to complex diagnostic and therapeutic trivalent radiometals under mild conditions. This study presents a comparison of  68 Ga,  44 Sc and  177 Lu-labeled AAZTA 5 -PSMA-617 with DOTA-PSMA-617 analogues. We evaluated the radiolabeling characteristics, in vitro stability of the radiolabeled compounds and evaluated their binding affinity and internalization behavior on LNCaP tumor cells in direct comparison to the radiolabeled DOTA-conjugated PSMA-617 analogs.    Results  AAZTA 5  was synthesized in a five-step synthesis and coupled to the PSMA-617 backbone on solid phase. Radiochemical evaluation of AAZTA 5 -PSMA-617 with  68 Ga,  44 Sc and  177 Lu achieved quantitative radiolabeling of > 99% after less than 5 min at room temperature. Stabilities against human serum, PBS buffer and EDTA and DTPA solutions were analyzed. While there was a small degradation of the  68 Ga complex over 2 h in human serum, PBS and EDTA/DTPA, the  44 Sc and  177 Lu complexes were stable at 2 h and remained stable over 8 h and 1 day. For all three compounds, i.e. [ nat Ga]Ga-AAZTA 5 -PSMA-617, [ nat Sc]Sc-AAZTA 5 -PSMA-617 and [ nat Lu]Lu-AAZTA 5 -PSMA-617, in vitro studies on PSMA-positive LNCaP cells were performed in direct comparison to radiolabeled DOTA-PSMA-617 yielding the corresponding inhibition constants (K i ). K i  values were in the range of 8–31 nM values which correspond with those of [ nat Ga]Ga-DOTA-PSMA-617, [ nat Sc]Sc-DOTA-PSMA-617 and [ nat Lu]Lu-DOTA-PSMA-617, i.e. 5–7 nM, respectively. Internalization studies demonstrated cellular membrane to internalization ratios for the radiolabeled  68 Ga,  44 Sc and  177 Lu-AAZTA5-PSMA-617 tracers (13–20%IA/10 6  cells) in the same range as the ones of the three radiolabeled DOTA-PSMA-617 tracers (17–20%IA/10 6  cells) in the same assay.    Conclusions  The AAZTA 5 -PSMA-617 structure proved fast and quantitative radiolabeling with all three radiometal complexes at room temperature, excellent stability with  44 Sc, very high stability with  177 Lu and medium stability with  68 Ga in human serum, PBS and EDTA/DTPA solutions. All three AAZTA 5 -PSMA-617 tracers showed binding affinities and internalization ratios in LNCaP cells comparable with that of radiolabeled DOTA-PSMA-617 analogues. Therefore, the exchange of the chelator DOTA with AAZTA 5  within the PSMA-617 binding motif has no negative influence on in vitro LNCaP cell binding characteristics. In combination with the faster and milder radiolabeling features, AAZTA 5 -PSMA-617 thus demonstrates promising potential for in vivo application for theranostics of prostate cancer.

68Ga, 44Sc and 177Lu-labeled AAZTA5-PSMA-617: synthesis, radiolabeling, stability and cell binding compared to DOTA-PSMA-617 analogues