Affiliation:
1. Department of Chemistry and Chemical Biology Cornell University Ithaca New York 14853 USA
2. Department of Chemistry Stony Brook University Stony Brook New York 11794 USA
3. Department of Medical Physics and Department of Radiology University of Wisconsin-Madison Madison Wisconsin 53706 USA
4. Department of Radiology University of Alabama at Birmingham Birmingham Alabama 35294 USA
Abstract
AbstractTo harness radiometals in clinical settings, a chelator forming a stable complex with the metal of interest and targets the desired pathological site is needed. Toward this goal, we previously reported a unique set of chelators that can stably bind to both large and small metal ions, via a conformational switch. Within this chelator class, py‐macrodipa is particularly promising based on its ability to stably bind several medicinally valuable radiometals including large 132/135La3+, 213Bi3+, and small 44Sc3+. Here, we report a 10‐step organic synthesis of its bifunctional analogue py‐macrodipa‐NCS, which contains an amine‐reactive −NCS group that is amenable for bioconjugation reactions to targeting vectors. The hydrolytic stability of py‐macordipa‐NCS was assessed, revealing a half‐life of 6.0 d in pH 9.0 aqueous buffer. This bifunctional chelator was then conjugated to a prostate‐specific membrane antigen (PSMA)‐binding moiety, yielding the bioconjugate py‐macrodipa‐PSMA, which was subsequently radiolabeled with large 132/135La3+ and small 47Sc3+, revealing efficient and quantitative complex formation. The resulting radiocomplexes were injected into mice bearing both PSMA‐expressing and PSMA‐non‐expressing tumor xenografts to determine their biodistribution patterns, revealing delivery of both 132/135La3+ and 47Sc3+ to PSMA+ tumor sites. However, partial radiometal dissociation was observed, suggesting that py‐macrodipa‐PSMA needs further structural optimization.
Funder
National Science Foundation
U.S. Department of Energy