Issue 42, 2017

Novel bifunctional DATA chelator for quick access to site-directed PET 68Ga-radiotracers: preclinical proof-of-principle with [Tyr3]octreotide

Abstract

Molecular imaging of tumors with the PET radionuclide 68Ga has gained momentum in clinical oncology due to the expanding availability of commercial 68Ge/68Ga-generators in combination with state-of-the-art PET/CT and PET/MRI hybrid imaging systems. Concurrently, interesting peptide-based or small-size vectors have been developed for theranostic use in cancer patients. Owing to the short half-life of 68Ga (t1/2 = 67.7 min) and the sensitivity of many targeting biomolecules, labeling and kit reconstitution in mild conditions allowing for quick access to ready-for-injection PET-tracers are highly desirable. The novel DATA ((6-pentanoic acid)-6-(amino)methy-1,4-diazepinetriacetate) chelator previously showing promising qualities for kit type labeling, was coupled to TOC ([Tyr3]octreotide). We herein report results from a first proof-of-principle study directly comparing 67Ga-DATA-TOC with the well-established 67Ga-DOTA-TOC in a series of preclinical models. Both analogs were shown to be sst2-preferring and specifically internalized in AR42J and HEK293-hsst2 cells, with 67Ga-DOTA-TOC internalizing faster in both cell lines. Similarly, after injection in mice bearing either AR42J or HEK293-hsst2 tumors, both tracers efficiently and specifically localized in the implants. Whereas 67Ga-DOTA-TOC exhibited higher tumor values, 67Ga-DATA-TOC cleared faster from background tissues. These findings support the suitability of the newly introduced bifunctional chelator DATA as a reliable, quick and convenient means for labeling medically relevant vectors with the PET radiometal 68Ga.

Graphical abstract: Novel bifunctional DATA chelator for quick access to site-directed PET 68Ga-radiotracers: preclinical proof-of-principle with [Tyr3]octreotide

Article information

Article type
Paper
Submitted
09 Mai 2017
Accepted
23 Jun 2017
First published
27 Jun 2017

Dalton Trans., 2017,46, 14584-14590

Novel bifunctional DATA chelator for quick access to site-directed PET 68Ga-radiotracers: preclinical proof-of-principle with [Tyr3]octreotide

B. A. Nock, A. Kaloudi, J. Nagel, J. Sinnes, F. Roesch and T. Maina, Dalton Trans., 2017, 46, 14584 DOI: 10.1039/C7DT01684K

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