title: Preliminary Therapy Evaluation of (225)Ac-DOTA-c(RGDyK) Demonstrates that Cerenkov Radiation Derived from (225)Ac Daughter Decay Can Be Detected by Optical Imaging for In Vivo Tumor Visualization.
abstract: The theranostic potential of (225)Ac-based radiopharmaceuticals continues to increase as researchers seek innovative ways to harness the nuclear decay of this radioisotope for therapeutic and imaging applications. This communication describes the evaluation of (225)Ac-DOTA-c(RGDyK) in both biodistribution and Cerenkov luminescence imaging (CLI) studies. Initially, La-DOTA-c(RGDyK) was prepared as a non-radioactive surrogate to evaluate methodologies that would contribute to an optimized radiochemical synthetic strategy and estimate the radioactive conjugate's affinity for αvβ3, using surface plasmon resonance spectroscopy. Surface plasmon resonance spectroscopy studies revealed the IC50 and Ki of La-DOTA-c(RGDyK) to be 33 ± 13 nM and 26 ± 11 nM, respectively, and suggest that the complexation of the La(3+) ion to the conjugate did not significantly alter integrin binding. Furthermore, use of this surrogate allowed optimization of radiochemical synthesis strategies to prepare (225)Ac-DOTA-c(RGDyK) with high radiochemical purity and specific activity similar to other (225)Ac-based radiopharmaceuticals. This radiopharmaceutical was highly stable in vitro. In vivo biodistribution studies confirmed the radiotracer's ability to target αvβ3 integrin with specificity; specificity was detected in tumor-bearing animals using Cerenkov luminescence imaging. Furthermore, tumor growth control was achieved using non-toxic doses of the radiopharmaceutical in U87mg tumor-bearing nude mice. To our knowledge, this is the first report to describe the CLI of αvβ3 (+) tumors in live animals using the daughter products derived from (225)Ac decay in situ. This concept holds promise to further enhance development of targeted alpha particle therapy.
authors.affiliation: 1. Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;
authors.forename: Darpan N
authors.initials: DN
authors.lastname: Pandya
authors.affiliation: 2. Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;
authors.forename: Roy
authors.initials: R
authors.lastname: Hantgan
authors.affiliation: 3. Small Animal Imaging Laboratory, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL 33612 USA;
authors.forename: Mikalai M
authors.initials: MM
authors.lastname: Budzevich
authors.affiliation: 4. Department of Pathology-Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Kock
authors.affiliation: 5. Department of Cancer Imaging and Metabolism, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL 33612 USA;
authors.forename: David L
authors.initials: DL
authors.lastname: Morse
authors.affiliation: 6. Department of Neurosurgery, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;
authors.forename: Izadora
authors.initials: I
authors.lastname: Batista
authors.affiliation: 1. Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;; 6. Department of Neurosurgery, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;; 7. Department of Radiology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Akiva
authors.initials: A
authors.lastname: Mintz
authors.affiliation: 7. Department of Radiology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: King C
authors.initials: KC
authors.lastname: Li
authors.affiliation: 1. Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA;; 7. Department of Radiology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
authors.forename: Thaddeus J
authors.initials: TJ
authors.lastname: Wadas
mesh_terms: D000818:Animals; D056831:Coordination Complexes / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D008819:Mice, Nude; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D061848:Optical Imaging / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: C000612800:(225)Ac-DOTA-c(RGDyK); D056831:Coordination Complexes; D039302:Integrin alphaVbeta3; D019275:Radiopharmaceuticals
keywords: Actinium-225; Cerenkov Luminescence Imaging; Targeted Alpha Particle Therapy; αvβ3 integrin.