Abstract
Purpose: Positron emission tomography (PET) and single photon emission computed tomography (SPECT) tracers have been applied to pharmacokinetic, pharmacodynamic, dose-finding, and proof-of-concept studies. PET/SPECT tracers could non-invasively assess treatment endpoints for diseases which used to rely on biopsies and histopathological assays. 18F-Fluorodeoxyglucose (FDG) is a gold standard for PET to detect unsuspected distant metastases in cancers. However, 18F-FDG has difficulties in distinguishing between inflammation/infection related masses versus cancer recurrence. Also, tumors with low glycolysis show poor FDG uptake, which leads to the high rate of false-negative results. Recent studies indicate that radiolabeled tyrosine derivatives using L-type amino acid transporters (LAT) can differentiate cancer from inflammation. Methods: We have synthesized 99mTc- and 68Ga-labeled chelator-based tyrosine analogs and their potential uses as kit probes for molecular radiotheranostic of tumors were evaluated. Results: The active ingredient in the kit is considered a drug substance, which allows standardization for chemistry, manufacturing and control (CMC). CMC is a crucial element in the centralized Investigational New Drugs (IND) process, and can be readily solved with kit probes. Conclusion: The use of PET and SPECT tracers has also helped to control and monitor dosage for increased safety and effectiveness, which have high impact on economy.
Keywords: LAT, technetium-99m, gallium-68, fluorine-18, iodine-131
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