Clinical production, stability studies and PET imaging with 16-alpha-[18F]fluoroestradiol ([18F]FES) in ER positive breast cancer patients.
OBJECTIVE
18F-Fluoroestradiol [18F]FES has emerged as a valuable PET tracer to predict the response to hormone therapy in recurrent or metastatic breast cancer patients. A clinically acceptable product requires a rapid reliable synthesis and must be demonstrated to maintain chemical stability and receptor specific uptake during patient studies. [18F]FES then becomes a dependable tracer for the evaluation and management of breast cancer patients.


METHODS
An improved automated radiosynthesis of [18F]FES was developed. Stability studies of the injectible form of [18F]FES were performed up to 24 h after dose formulation under normal storage conditions. A comparative FES/FDG PET imaging in ER+ breast cancer patients is reported.


RESULTS
The improved synthesis procedure utilizes fewer hydrolysis steps and a single high performance liquid column chromatography (HPLC) purification of the labeled mixture affording [18F]FES in good yield with high radiochemical purity (>99%). Stability studies with purified [18F]FES in saline/ethanol (85:15 v/v) indicated no radiolytic or chemical degradation of this radiopharmaceutical when stored for 24 h at 20-24 degrees C. Positron Emission Tomography (PET) studies with [18F]FES and [18F]FDG in estrogen receptor positive (ER+) breast cancer patients indicated that while FDG accumulation was seen in all metabolically hyperactive sites, the uptake of FES clearly delineated the ER+ tissues regions.


CONCLUSIONS
An improved automated synthesis of [18F]FES has been developed and the integrity of this product has been validated by long term stability studies and clinical PET imaging studies in ER+ breast cancer patients. A lack of concordance between FES and FDG uptake in a patient with metastatic breast cancer suggests specificity of the FES for tumors expressing estrogen receptors.
Kumar
Piyush
P
Department of Oncologic Imaging, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada T6G 1Z2. piyushku@cancerboard.ab.ca
Mercer
John
J
Doerkson
Courtney
C
Tonkin
Katia
K
McEwan
Alexander J B
AJ
D001331:Automation; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004356:Drug Storage; D004958:Estradiol / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D005260:Female; D005462:Fluorine Radioisotopes; D006801:Humans; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D011960:Receptors, Estrogen / Q000378:metabolism; D012680:Sensitivity and Specificity
D005462:Fluorine Radioisotopes; D011960:Receptors, Estrogen; D004958:Estradiol; C043436:16-fluoroestradiol