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In Vivo and in Vitro Steroid Receptor Assays in the Design of Estrogen Radiopharmaceuticals
Published in William C. Eckelman, Lelio G. Colombetti, Receptor-Binding Radiotracers, 2019
John A. Katzenellenbogen, Daniel F. Heiman, Kathryn E. Carlson, John E. Lloyd
In conclusion, of the compounds we have examined, those that appear most promising as potential receptor-based imaging agents for human breast tumors on the basis of their receptor-binding affinities and their binding selectivity indexes are 2- and 4-fluoroestradiol; o-, m- and l-fluorohexestrols, and 16α-bromo and 16α-iodoestradiols. Other compounds that have affinities and selectivities which may be acceptable for imaging purposes are 16β-iodoestradiol, 1-bromo and 1-iodohexestrol, and α-iodo-α′-isopropylstilbestrol.
Halogen Labeled Compounds (F, Br, At, Cl) *
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Fluorinated compounds are not usually subject to in vivo dehalogenation as readily as iodinated compounds. It was shown that 4-fluoroestradiol exhibited high estrogenic activity as discussed in Section II.33,34 These prompted the syntheses of 18F-4-fluoroes-tradiol and 4-fluoroestrone were synthesized by Eakins et al.35 as potential agents for prostate imaging. Quite disappointingly, these two compounds did not show any selective localization in the prostate of rats as anticipated. Tissue distribution with these compounds showed that from 30 min to 2 hr after injection the major concentration of radioactivity was in the liver and duodenum. Since there was very little radioactivity in the bone (as expected with fluoride) the authors concluded that there was little in vivo defluorination. They attributed the low uptake in the prostate to the low specific activity, which is not uncommon with products prepared by a Schiemann reaction.
Biomedical Imaging Molecular Imaging
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Christian J. Konopka, Emily L. Konopka, Lawrence W. Dobrucki
Active vs. passively targeted. PET and SPECT contrast agents are generally termed radiotracers. These radiotracers can also be targeted or non-targeted contrast agents. The key difference between MI and nuclear medicine is that MI uses radiotracers and contrast agents that are specific for the measurement of a certain biological process, whereas nuclear medicine also uses radiotracers that are non-specific, but still clinically useful. For instance, SPECT tracer 67Ga-citrate is a SPECT radiotracer which can be useful for detecting malignant tumor tissue, but it is not specific for any molecular process; rather, it accumulates in tumor tissue because the 67Ga is treated as a ferrous ion in the body and accumulates in sites of inflammation such as cancer or infection sites. 67Ga-citrate uptake on SPECT or 2-D scintigraphy studies can therefore locate primary tumors, metastases, and infections. In contrast to 67Ga-citrate, 18F-fluoroestradiol (FES) is a MI radiotracer used for imaging breast cancers with PET. FES specifically binds to estrogen receptors and its uptake can predict the treatment effect of salvage hormonal therapy and guide therapeutic regimens for breast cancer patients (Linden et al. 2006).
Theranostic approaches in nuclear medicine: current status and future prospects
Published in Expert Review of Medical Devices, 2020
Luca Filippi, Agostino Chiaravalloti, Orazio Schillaci, Roberto Cianni, Oreste Bagni
Beyond the theranostic applications based on the clinical use of radionuclide pairs (diagnostic/therapeutic), theranostics also consist in the detection of specific biomarkers (i.e. receptors, transporters), that can be successfully exploited for targeted therapy. As specifically concerns breast cancer (BC), in the past years many advances have been made for the identification of several molecular targets linked to specific tumor biology and behavior, such as human epidermal growth factor 2 (HER-2), hormone receptors, gastrin releasing peptide receptor (GRPR), folate receptor (FR), etc. [78]. In particular, 16alpha-[(18)F]fluoroestradiol-17beta (18 F-FES) has been applied for the PET detection of estradiol receptor (ER) in patients affected by advanced BC. In a study performed by Dehdashti et al., a cohort of 51 post-menopausal women with advanced estrogen-receptor positive BC was submitted to PET/CT scan with 18 F-FES before treatment with estradiol, among the enrolled subjects, 17 responded and 31 did not respond to hormone therapy [79]. Of note, responders showed higher SUV values in tumors than non-responders, thus suggesting that PET with 18 F-FES may present a predictive value on the response to hormone therapy.
Latest generation estrogen receptor degraders for the treatment of hormone receptor-positive breast cancer
Published in Expert Opinion on Investigational Drugs, 2022
Ya-Chi Chen, Jiajie Yu, Ciara Metcalfe, Tom De Bruyn, Thomas Gelzleichter, Vikram Malhi, Pablo D. Perez-Moreno, Xiaojing Wang
This section provides an overview of available pharmacokinetic and pharmacodynamic data for novel oral SERDs from early clinical studies. [18 F]-fluoroestradiol positron emission tomography (FES-PET) imaging measures tumor uptake of radiolabeled estradiol and is used as a biomarker to infer ER occupancy by a competing drug and/or ER downregulation. Also, the clinical drug exposure and the selection of recommended Phase 2 dose (RP2D) are summarized in Table 2 if data are available or published.
2021 Oncology Coding Update
Published in Oncology Issues, 2021
A959: Fluoroestradiol F-18, diagnostic, 1 mCi.C9068: Copper Cu 64 dotatate, diagnostic, 1 mCi.J9198: Gemcitabine hydrochloride (Infugem), 100 mg.C9069: Injection, belantamab mafodontin-blmf, 0.5 mg.C9070: Injection, tafasitamab-cxix, 2 mg.C9073: Brexucabtagene autoleucel, up to 200 million autologous anti-CD19.J9316: Injection, pertuzumab, trastuzumab, and hyaluronidase-zzxf, per 10 mg.J9223: Injection, lurbinectedin, 0.1 mg.G2206: Patient received adjuvant treatment course including both chemotherapy and human epidermal growth factor receptor 2 (HER2)-targeted therapy.G2207: Reason for not administering adjuvant treatment course, including both chemotherapy and HER2-targeted therapy (e.g., poor performance status; ECOG = 3-4; Karnofsky = 50), cardiac contraindications, insufficient renal function, insufficient hepatic function, other active or secondary cancer diagnoses, other medical contraindications, patients who died during initial treatment course or transferred during or after initial treatment course.G2208: Patient did not receive adjuvant treatment course, including both chemotherapy and HER-targeted therapy.