Tumor Specific Imaging Using Tc-99m and Ga-68 Labeled Radiopharmaceuticals

Abstract

Improvement of scintigraphic tumor imaging is extensively determined by the development of more tumor specific radiopharmaceuticals. Thus, to improve the differential diagnosis, prognosis, planning and monitoring of cancer treatment, several functional pharmaceuticals have been developed. Application of molecular targets for cancer imaging, therapy and prevention using generator-produced isotopes are the major focus of ongoing research projects. Radionuclide imaging modalities (positron emission tomography, PET; single photon emission computed tomography, SPECT) are diagnostic cross-sectional imaging techniques that map the location and concentration of radionuclide-labeled radiotracers.99m Tc-and 68 Ga-labeled agents using ethylenedicysteine (EC) as a chelator were synthesized and their potential uses to assess tumor targets were evaluated.99m Tc (t 1/2 =6 hr, 140 keV) is used for SPECT and 68 Ga (t 1/2 =68 min, 511 keV) is for PET. Molecular targets labeled with Tc-99m and Ga-68 can be utilized for prediction of therapeutic response, monitoring tumor response to treatment and differential diagnosis. Molecular targets for oncological research in (1) cell apoptosis, (2) gene and nucleic acid-based approach, (3) angiogenesis (4) tumor hypoxia, and (5) metabolic imaging are discussed. Numerous imaging ligands in these categories have been developed and evaluated in animals and humans. Molecular targets were imaged and their potential to redirect optimal cancer diagnosis and therapeutics were demonstrated.

Study of Apoptosis Induced by 188Re-DTPA-DG in MCF-7 Breast Carcinoma and A549 Pulmonary Carcinoma Cells

“…Yang and colleagues [13][14][15] found that EC-DG, which has characteristics similar to those of glucosamine, can easily be transported into tumor cells and enters the glycolysis/tricarboxylic acid cycle. EC-DG is synthesized from glucosamine by insertion of a dicysteine group at the 2-amino position of the glucosamine molecule.…”

Technologies for Translational Imaging Using Generators in Oncology

“…L,L-ethylenedicysteine (EC) is the most successful example of N 2 S 2 chelates [14,[17][18][19]. EC can be labeled with both 68 Ga and 99m Tc efficiently with high radiochemical purity and the preparation remains stable for several hours [20].…”

“…The agents that could provide therapeutic prediction are either labeled molecular biomarkers or radiolabeled drugs. For example, radiolabeled annexin, a biomarker for apoptosis, is useful to evaluate the baseline level of apoptosis, predict the efficacy of therapy based on the detection of treatment-related apoptosis and possibly predict disease progression and prognosis [6,20,24]. As another example, assessment of pancreatic beta cell activity by a radiolabeled sulfonylurea receptor agent could provide early diagnosis of pancreatic diseases and monitor drug treatment response on pancreatic beta cells.…”

“…factors with cell cycle factors at basal levels of transcription or repression. Preclinical and clinical studies have shown that 99m Tc-EC-glucosamine is able to differentiate inflammation/infection and tumor growth in animal models and in humans [20,34,35].…”

Synthesis and evaluation of two novel 2-nitroimidazole derivatives as potential PET radioligands for tumor imaging

“…However, [ 18 F]FMISO ( 1 ) was not an optimal hypoxic imaging agent. Because of the partitioning mechanism, [ 18 F]FMISO ( 1 ) shows a reduced accumulation of radioactivity in hypoxic cells and slow clearance in normal cells that lead to low tumor-to-background (T/B) ratios [8, 15]. Thus, new imaging agents with faster pharmacokinetics for ensuring higher T/B ratios are required.…”