1
|
Ferrier MG, Li Y, Chyan MK, Wong R, Li L, Spreckelmeyer S, Hamlin DK, Mastren T, Fassbender ME, Orvig C, Wilbur DS. Thorium chelators for targeted alpha therapy: Rapid chelation of thorium-226. J Labelled Comp Radiopharm 2020; 63:502-516. [PMID: 32812275 DOI: 10.1002/jlcr.3875] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 08/06/2020] [Accepted: 08/06/2020] [Indexed: 12/26/2022]
Abstract
One of the main challenges in targeted alpha therapy is assuring delivery of the α-particle dose to the targeted cells. Thus, it is critical to identify ligands for α-emitting radiometals that will form complexes that are very stable, both in vitro and in vivo. In this investigation, thorium-227 (t1/2 = 18.70 days) chelation of ligands containing hydroxypyridinonate (HOPO) or picolinic acid (pa) moieties and the stability of the resultant complexes were studied. Chelation reactions were followed by reversed-phased HPLC and gamma spectroscopy. Studies revealed that high 227 Th chelation yields could be obtained within 2.5 h or less with ligands containing four Me-3,2-HOPO moieties, 1 (83%) and 2 (65%), and also with ligands containing pa moieties, H4 octapa 3 (65%) and H4 py4pa 6 (87%). No reaction occurred with H4 neunpa-p-Bn-NO2 4, and the chelation reaction with another pa ligand H4 pypa 5 gave inconsistent yields with a very broad radio-HPLC peak. The ligands spermine-(Me-3,2-HOPO)4 1, H4 octapa 3, and H4 py4pa 6 had high stability (i.e., 87% of 227 Th still bound to the ligand) in phosphate-buffered saline at room temperature over a 6-day period. Preliminary studies with ligand 6 demonstrated efficient chelation of thorium-226 (t1/2 = 30.57 min) when heated to 80°C for 5 min.
Collapse
Affiliation(s)
- Maryline G Ferrier
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA.,Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California, USA
| | - Yawen Li
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Ming-Kuan Chyan
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Roger Wong
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Lily Li
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.,Life Sciences Division, TRIUMF, Vancouver, British Columbia, Canada
| | - Sarah Spreckelmeyer
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Donald K Hamlin
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Tara Mastren
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | | | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - D Scott Wilbur
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| |
Collapse
|