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A New, Second Generation Trithiol Bifunctional Chelate for 72,77As: Trithiol(b)-(Ser)2-RM2
Firouzeh Najafi Khosroshahi, Yutian Feng, Li Ma
1Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, Missouri 65201, United States.
Bioconjugate Chemistry
|January 11, 2021
Summary
New radiopharmaceuticals using arsenic isotopes show promise for cancer theranostics. Researchers developed a novel arsenic-labeled bioconjugate for targeted imaging and therapy of gastrin-releasing peptide receptor-expressing tumors.
Area of Science:
- Nuclear chemistry
- Radiopharmaceutical science
- Oncology
Background:
- Trithiol chelates are effective for labeling radioarsenic isotopes like 72As and 77As.
- These radioarsenic compounds can be developed into theranostic radiopharmaceuticals for positron emission tomography (PET) imaging and therapy.
- The gastrin-releasing peptide (GRP) receptor is a target for certain cancers.
Purpose of the Study:
- To synthesize and characterize a trithiol(b)-(Ser)2-RM2 bioconjugate and its arsenic complex.
- To evaluate the radiolabeling efficiency, stability, and GRP receptor binding affinity of the arsenic-trithiol bioconjugate.
- To perform preliminary biodistribution studies of the radiolabeled compound in mice.
Main Methods:
- Synthesis and characterization of a trithiol(b)-(Ser)2-RM2 bioconjugate.
- Radiolabeling with no-carrier-added 77As.
- In vitro stability assays and IC50 cell binding studies in PC-3 cells.
- High-performance liquid chromatography (HPLC) purified biodistribution studies in normal mice.
Main Results:
- The trithiol(b)-(Ser)2-RM2 bioconjugate was successfully synthesized and formed an arsenic complex.
- Radiolabeling with 77As achieved over 95% radiochemical yield, with the radiolabeled complex remaining stable for over 48 hours.
- In vitro studies showed high affinity for the gastrin-releasing peptide (GRP) receptor (low nanomolar range) in PC-3 cells.
- Biodistribution studies indicated pancreatic uptake and hepatobiliary clearance of the 77As-labeled compound.
Conclusions:
- The developed arsenic-trithiol bioconjugate is a promising platform for creating theranostic radiopharmaceuticals.
- The compound demonstrates efficient radiolabeling, stability, and specific binding to the GRP receptor.
- Further investigation is warranted for its potential application in cancer imaging and therapy.
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