Assessment of Therapeutic Tumor Response Using 99mTc-Ethylenedicysteine-Glucosamine

The Preparation and Execution of Exploratory Human Studies on Novel 99mTc-Labeled Glucosamine Derivatives Containing Different Phenyl Isonitriles as Promising Tumor Imaging Agents

As the "molecule of the century", 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) is a radioactive 18F-labeled glucose derivative with a wide range of applications for positron emission tomography (PET) imaging. Single photon emission computed tomography (SPECT) imaging is widely used, but there is no clinical probe comparable to [18F]FDG. In our previous work, [99mTc]Tc-CN5DG and [99mTc]Tc-CN7DG were successfully developed and achieved high-quality SPECT images. However, they still have the disadvantage of low tumor uptake and/or high uptake by nontarget organs. To develop novel tumor imaging agents with high tumor uptake and excellent tumor/nontarget ratios, in this study, starting from d-glucosamine hydrochloride, four phenyl group-containing isonitrile ligands were designed, synthesized, and radiolabeled with 99mTc. All the complexes had high radiochemical purity and good hydrophilicity and stability. Biodistribution experiments showed that [99mTc]Tc-L4 (i.e., [99mTc]Tc-CNMBDG) had the highest tumor uptake and tumor/background ratios among the four probes. In SPECT imaging studies, the tumor detected by [99mTc]Tc-L4 was more clearly visible than that of [99mTc]Tc-CN7DG because of the inappreciable interference from abdominal uptake. Preliminary clinical studies of [99mTc]Tc-L4 have been conducted and successfully showed the lesion location in a patient with non-small-cell lung cancer. In summary, [99mTc]Tc-L4 is expected to be a promising tumor SPECT imaging agent.

Modulators of radiation-induced cardiopulmonary toxicities for non-small cell lung cancer: Integrated cytokines, single nucleotide variants, and HBP systems imaging

Radiation therapy (RT)-induced cardiopulmonary toxicities remain dose-limiting toxicities for patients receiving radiation dosages to the thorax, especially for lung cancer. Means of monitoring and predicting for those receiving RT or concurrent chemoradiation therapy before treatment begins in individual patients could benefit early intervention to prevent or minimize RT-induced side effects. Another aspect of an individual's susceptibility to the adverse effects of thoracic irradiation is the immune system as reflected by phenotypic factors (patterns of cytokine expressions), genotypic factors (single nucleotide variants SNVs; formerly single nucleotide polymorphisms [SNPs]), and aspects of quantitative cellular imaging. Levels of transcription, production, and functional activity of cytokines are often influenced by SNVs that affect coding regions in the promoter or regulatory regions of cytokine genes. SNVs can also lead to changes in the expression of the inflammatory cytokines, interferons, interleukins (IL-6, IL-17) and tumor necrosis factors (TNF-α) at the protein level. RT-induced cardiopulmonary toxicities could be quantified by the uptake of ¹⁸F-fluorodeoxyglucose (FDG), however, FDG is a sensitive but not specific biomarker in differential diagnosis between inflammation/infection and tumor recurrence. FDG is suitable for initial diagnosis of predisposed tissue injuries in non-small cell lung cancer (NSCLC). ^99mTc-ethylenedicysteine-glucosamine (^99mTc-EC-G) was able to measure tumor DNA proliferation and myocardial ischemia via hexosamine biosynthetic pathways (HBP). Thus, ^99mTc-EC-G could be an alternative to FDG in the assessment of RT doses and select patients in HBP-directed targets for optimal outcomes. This article reviewed correlative analyses of pro-inflammatory cytokines, genotype SNVs, and cellular imaging to improve the diagnosis, prognosis, monitoring, and prediction of RT-induced cardiopulmonary toxicities in NSCLC.

Glycoconjugated Metal Complexes as Cancer Diagnostic and Therapeutic Agents

The possibility of selectively delivering metal complexes to a defined cohort of cells on the basis of their metabolic features is a highly challenging goal, which may be extremely useful for a series of purposes, including diagnosis and therapy of pathological states, such as cancer. Tumor cells display augmented requests for carbohydrates and, in particular, for glucose in order to sustain their high proliferation rate, which causes an increased glycolytic process (Warburg effect). Since several metal complexes display diagnostic and/or therapeutic properties, their conjugation to carbohydrate portions often induce their preferential accumulation in cancer cells, similarly to what is observed with fluorodeoxyglucose (FDG). In this review we have considered the latest developments of glycoconjugates containing metal complexes in their structures. These compounds are classified as diagnostic or therapeutic agents and are further systematically discussed on the basis of the metal atom they contain. Several diagnostic techniques are possible with these probes, since, depending on the metal species included in their structures, they may be employed in nuclear medicine (PET, SPECT), magnetic resonance imaging, luminescence and phosphorescence. At the same time, the lack of selective cytotoxicity displayed by several metal-based chemotherapeutic agents, may also be solved by the conjugation of these agents to carbohydrate portions. Overall, data so far available reveal the great potential of this chemical class in the early detection and in the cure of severe neoplastic diseases, which still needs to be fully explored in the clinic.

Noninferiority of 99mTc-Ethylenedicysteine-Glucosamine as an Alternative Analogue to 18F-Fluorodeoxyglucose in the Detection and Staging of Non-Small Cell Lung Cancer

Objective. ^99mTc-ethylenedicysteine-glucosamine (^99mTc-EC-G) was developed as a potential alternative to ¹⁸F-FDG for cancer imaging. A Phase 2 study was conducted to compare ¹⁸F-FDG PET/CT and ^99mTc-EC-G SPECT/CT in the detection and staging of patients with non-small cell lung cancer (NSCLC). This study was aimed to demonstrate that ^99mTc-EC-G SPECT/CT was not inferior to ¹⁸F-FDG PET/CT in patients with confirmed NSCLC. Methods. Seventeen patients with biopsy proven NSCLC were imaged with ^99mTc-EC-G and ¹⁸F-FDG to detect and stage their cancers. Imaging with PET/CT began 45–60 minutes after injection of ¹⁸F-FDG. Imaging with ^99mTc-EC-G began at two hours after injection (for 5 patients) or three hours (for 12 patients). SPECT/CT imaging devices from the three major vendors of SPECT/CT systems were used at 6 participating study sites. The image sets were blinded to all clinical information and interpreted by independent PET and SPECT expert readers at a central independent core laboratory. Results. 100% concordance between ^99mTc-EC-G and ¹⁸F-FDG for primary lesion detection, lesion location and size, and confidence that the biopsied lesion was malignant. There was 70% agreement between ^99mTc-EC-G and ¹⁸F-FDG for metastatic lesion detection, location and size, and confidence that the suspicious lesions were malignant. Conclusions. Evaluation of primary and suspicious metastatic lesions detected by ^99mTc-EC-G and ¹⁸F-FDG on 17 patients resulted in excellent agreement for detection of primary and metastatic lesions. The study results indicated that ^99mTc-EC-G SPECT/CT has the potential to be a clinically viable alternative to ¹⁸F-FDG PET/CT and ^99mTc-EC-G is not inferior to ¹⁸F-FDG PET/CT.

Evaluating disease activity in patients with ankylosing spondylitis and rheumatoid arthritis using 99mtc-glucosamine

OBJECTIVE

To evaluate the clinical utility of a novel radiotracer, ^99mTc-glucosamine, in assessing disease activity of both rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Material and Methods: Twenty-five patients with RA (nine males and 16 females) and 12 patients with AS (all male) at various stages of disease were recruited for the study. A clinical history and examination was performed, followed by the measurement of hematological, biochemical, and autoimmune serological parameters to assess disease activity. ^99mTc-glucosamine was intravenously administered and scans were compared with other imaging modalities, including plain X-ray, magnetic resonance imaging (MRI), and bone scans.

RESULTS

In patients with AS, ^99mTc-glucosamine scans were more capable of identifying active disease and differentiating between inflammatory and non-inflammatory causes. In patients with RA, ^99mTc-glucosamine accumulated at all known sites of disease involvement. Uptake was most pronounced in patients with active untreated disease. The relative tracer activity in the involved joints increased with time compared with that in the adjoining soft tissue, liver, and cardiac blood pool. Using Spearman's correlation coefficient, there was a positive correlation among glucosamine scan scores, C-reactive protein (p=0.048), and clinical assessment (p=0.003), which was not noted with bone scans.

CONCLUSION

The radiotracer was well tolerated by all patients, with no adverse reactions. ^99mTc-glucosamine imaging could detect spinal inflammation in AS. With respect to RA, ^99mTc-glucosamine was a viable alternative to ^99mTc-labeled methylene diphosphonate nuclear bone scans for imaging inflamed joints and had the added advantage of demonstrating a significant clinical correlation between disease activity and scan findings.

Molecular imaging of mesothelioma with (99m)Tc-ECG and (68)Ga-ECG

We have developed ethylenedicysteine-glucosamine (ECG) as an alternative to (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) for cancer imaging. ECG localizes in the nuclear components of cells via the hexosamine biosynthetic pathway. This study was to evaluate the feasibility of imaging mesothelioma with (99m)Tc-ECG and (68)Ga-ECG. ECG was synthesized from thiazolidine-4-carboxylic acid and 1,3,4,6-tetra-O-acetyl-2-amino-D-glucopyranose, followed by reduction in sodium and liquid ammonia to yield ECG (52%). ECG was chelated with (99m)Tc/tin (II) and (68)Ga/(69)Ga chloride for in vitro and in vivo studies in mesothelioma. The highest tumor uptake of (99m)Tc-ECG is 0.47 at 30 min post injection, and declined to 0.08 at 240 min post injection. Tumor uptake (%ID/g), tumor/lung, tumor/blood, and tumor/muscle count density ratios for (99m)Tc-ECG (30-240 min) were 0.47 ± 0.06 to 0.08 ± 0.01; 0.71 ± 0.07 to 0.85 ± 0.04; 0.47 ± 0.03 to 0.51 ± 0.01, and 3.49 ± 0.24 to 5.06 ± 0.25; for (68)Ga-ECG (15-60 min) were 0.70 ± 0.06 to 0.92 ± 0.08; 0.64 ± 0.05 to 1.15 ± 0.08; 0.42 ± 0.03 to 0.67 ± 0.07, and 3.84 ± 0.52 to 7.00 ± 1.42; for (18)F-FDG (30-180 min) were 1.86 ± 0.22 to 1.38 ± 0.35; 3.18 ± 0.44 to 2.92 ± 0.34, 4.19 ± 0.44 to 19.41 ± 2.05 and 5.75 ± 2.55 to 3.33 ± 0.65, respectively. Tumor could be clearly visualized with (99m)Tc-ECG and (68)Ga-ECG in mesothelioma-bearing rats. (99m)Tc-ECG and (68)Ga-ECG showed increased uptake in mesothelioma, suggesting they may be useful in diagnosing mesothelioma and also monitoring therapeutic response.

Radiation dosimetry and biodistribution of (99m)Tc-ethylene dicysteine-deoxyglucose in patients with non-small-cell lung cancer

Purpose

To assess the radiation dosimetry and biodistribution of ^99mTc-labeled ethylene dicysteine deoxyglucose (^99mTc-EC-DG) in patients with non-small-cell lung cancer (NSCLC).

Methods

Serial whole-body scans were acquired 0, 2, 4, 6 and 24 h after injection of ^99mTc-EC-DG (925 MBq) in seven NSCLC patients. Radiation dosimetry, blood clearance and SPECT imaging of the primary tumor were assessed.

Results

The critical organ was the bladder wall, with average radiation absorbed dose over all seven patients of 2.47×10⁻² mGy/MBq. The average effective dose equivalent and effective dose were 6.20×10⁻³ mSv/MBq (6.89 mSv/1,110 MBq) and 5.90×10⁻³ mSv/MBq (6.54 mSv/1,110 MBq), respectively. The primary tumor was visualized with SPECT in six patients. On final pathology, one patient had a granuloma, which did not enhance with ^99mTc-EC-DG.

Conclusion

^99mTc-EC-DG has acceptable dosimetric and biodistribution properties as a diagnostic tumor-imaging agent. Future studies are planned to evaluate its diagnostic potential.

Molecular imaging of Bcr-Abl phosphokinase in a xenograft model

The purpose of this study was to determine whether the Bcr-Abl tyrosine kinase can be assessed by gamma-imaging using an 111In-labeled anti-phosphotyrosine (APT) antibody, and if the response to treatment with imatinib could be detected using this imaging technique. APT antibody was labeled with 111In using ethylenedicysteine (EC) as a chelator. To determine if 111In-EC-APT could assess a nonreceptor tyrosine kinase, xenografts of the human chronic myelogenous leukemia cell line K562 were used. gamma-Scintigraphy of the tumor-bearing mice, before and after imatinib treatment, was obtained 1, 24, and 48 h after they were given 111In-EC-APT (100 microCi/mouse i.v.). 111In-EC-APT is preferentially taken up by Bcr-Abl-bearing tumor cells when compared with 111In-EC-BSA or 111In-EC-IgG1 controls and comparable with the level of uptake of 111In-EC-Bcr-Abl. Imatinib treatment resulted in decreased expression of phospho-Bcr-Abl by Western blot analysis, which correlated with early (4 days after starting imatinib) kinase down-regulation as assessed by imaging using 111In-EC-APT. The optimal time to imaging was 24 and 48 h after injection of 111In-EC-APT. Although tumor regression was insignificant on day 4 after starting imatinib treatment, it was marked by day 14. 111In-EC-APT can assess intracellular phosphokinase activity, and down-regulation of phosphokinase activity predates tumor regression. This technique may therefore be useful in the clinic to detect the presence of phosphokinase activity and for early prediction of response.

99m-Technetium carbohydrate conjugates as potential agents in molecular imaging

This feature article covers recent reports of work towards the development of (99m)Tc-carbohydrate based agents for use in SPECT imaging, particularly of cancerous tissue. An outline of some of the key biological functions and coordination chemistry of carbohydrates is given, along with an introduction to bioconjugation and molecular imaging. Technetium coordination chemistry and the subset of this involving bioconjugates are discussed before moving into the focus of the article: glycoconjugates of (99m)Tc(v) and the more recently developed [(99m)Tc(I)(CO)(3)](+). Significant work in the last decade has featured the very attractive [(99m)Tc(CO)(3)](+) core, and the ligand sets designed for this core are discussed in detail.

Review: Deoxyglucose compounds labeled with isotopes different from 18-fuoride: is there a future in clinical practice?

There are several radionuclide-labeled derivatives of deoxyglucose (DG) that have been developed including 2-fluro-deoxyglucose, ethylenedicysteine-deoxyglucose, diethylenetriaminepentaacetate-deoxyglucose, N-(2'-hydroxybenzyl)-2-amino-2-deoxy-D-glucose, and methyl D-glucoside that were synthesized and successfully labeled in high labeling fields. The former 4 were used for tumor imaging and methyl-D-glucoside for the diagnosis and the monitoring of the functional status of renal tubules. These derivatives are suitable for imaging examinations when labeled with either fluorine-18 (18F), technetium-99m (99mTc), carbon-11 (11C), or gallium-68 (68Ga). These compounds are suitable both for imaging and for therapy if labeled with rhenium-188 (188Re). In the area of molecular imaging of nuclear medicine, derivatives of radionuclide-labeled deoxyglucose will become an important tool for the diagnosis and carcinoma treatment in the clinic.

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

OBJECTIVE

To evaluate apoptosis induced by rehenium-188-labeled diethylenetriamine pentaacetic acid-glucosamine (188Re-DTPA-DG) in MCF-7 breast carcinoma cells and A549 pulmonary carcinoma cells.

METHODS

Through the use of flow cytometry (FCM) with CBA software to detect apoptosis, cells of both the MCF-7 and A549 cell lines were divided into groups exposed to 188Re-DTPA-DG, 188Re-perrhenate (188ReO4-), and saline, respectively. The first two groups were further divided into subgroups on the basis of their exposure to radioactivity at 37, 55.5, or 74 kBq/mL, with the saline-exposed group divided into three corresponding subgroups. Each subgroup was introduced into 5 replicate wells of a culture plate, and the morphology of the cells in each well was determined by flow cytometry at 6-hour intervals for 18 hours. In order to determine the affinity of 188Re-DTPA-DG for tumor tissue, the biodistribution of the radiolabeled agent was assessed in breast tumor-bearing nude mice.

RESULTS

Change in morphology of the cell nucleus was more evident in the 188Re-DTPA-DG-treated than in the 188ReO4--treated group, and no change in nuclear morphology was seen in the saline-exposed group. The study data suggested that there was a greater ratio of apoptotic to nonapoptotic cells among the 188Re-DTPA-DG-treated than among the 188ReO4--treated or saline-exposed cells (p<0.01), and a greater change in cell-nuclear morphology in the 188Re-DTPA-DG-treated than in the 188ReO4--treated cells. Furthermore, 188Re-DTPA-DG had a more significant apoptosis-inducing effect on both MCF-7 and A549 cells than did 188ReO4-. The biodistribution study in tumor-bearing nude mice showed that the concentration of 188Re-DTPA-DG in tumor tissue was much higher than in normal tissue, that 188Re-DTPA-DG was rapidly cleared from the blood, and that the main route of its clearance was via the kidneys.

CONCLUSIONS

188Re-DTPA-DG has a significant apoptotic effect on carcinoma cells. 188Re-DTPA-DG is an effective radiopharmaceutical for intratumoral radiation therapy.

Noninvasive Scintigraphic Detection of Tumor with 99mTc-DTPA-Deoxyglucose: An Experimental Study

OBJECTIVES

Glucosamine is a highly attractive scaffold for a glucosyl ligand, and shows activity with glucose transporters and hexokinase. In the study reported here, diethylenetriamine-pentaacetic acid-D-glucosamine (DTPA-DG) was synthesized by conjugating D-glucosamine to DTPA, and was labeled with technetium-99m ((99m)Tc). We investigated (99m)Tc-DTPA-DG for tumor detection.

METHODS

The biodistribution and imaging of (99m)Tc-DTPA-DG in mammary tumor-bearing mice were compared to those in a control group of mice with oleum terebinthinae (turpentine oil)-induced inflammation. Both groups of mice were given an intravenous injection of 3.7 MBq/0.1 mL of (99m)Tc-DTPA-DG through the tail vein.

RESULTS

(99m)Tc-DTPA-DG accumulated in the tumor tissue to a percentage of 2.10 +/- 0.02% of the injected dose per gram of tissue (%ID/g) at 2 hours after injection, versus an accumulation of 0.81 +/- 0.03%ID/g in the inflamed tissue. The tumor-to-contralateral muscle tissue ratio of (99m)Tc-DTPA-DG was 5.01 +/- 1.02, while the inflamed tissue-to-contralateral muscle tissue ratio was 1.2 +/- 0.08. Gamma-camera imaging revealed the tumor tissue at 2 hours after injection of (99m)Tc-DTPA-DG. The tumor-to-background ratio of (99m)Tc-DTPA-DG (3.8 +/- 0.95) at 2 hours was significantly (p < 0.05) higher in mammary tumor-bearing mice than was the inflamed tissue-to-background ratio (1.2 +/- 0.62) in the mice with inflammation.

CONCLUSIONS

(99m)Tc-DTPA-DG showed excellent tumor targeting and has promise as an imaging agent for clinical tumor targeting.

Preparation and Imaging Research on 188Re-DTPA-Deoxyglucose in MCF-7 Tumor-Bearing Mice

OBJECTIVE

To investigate the preparation of (188)Re-diethylenetriaminepentaacetic acid-2-deoxyglucose ((188)Re-DTPA-DG) and its imaging quality and therapeutic effect.

METHODS

Labeling of DTPA-DG with (188)Re was performed in the presence of stannous ion and sodium D-gluconate at a pH of 5.5 with 3 hours of incubation at 37 degrees C. The radiolabeling yields of (188)Re-DTPA-DG were determined by paper chromatography with a solution of acetone and saline (0.9% NaCl) as a developing agent. The imaging quality of (188)Re-DTPA-DG was determined by injecting 0.1 mL of a preparation having a radioactivity of 92.5GBq/L into the tail vein of nude mice bearing MCF-7 mammary tumors and imaging the tumors at 2, 4, 8, 12, and 24 hours after injection of the radiolabeled agent. Tumor volume was recorded every 2 or 3 days for 21 days.

RESULTS

The radiochemical purity of the (188)Re-DTPA-DG complex was 95.0%. In the imaging study, the tumor-to-nontumor-tissue ratios (T/NT) of radioactivity at 12 and 24 hours after intravenous injection of the radiolabeled agent were 5.9 and 7.8, respectively. The tumor volume in the (188)Re-DTPA-DG-treated group of mice increased more slowly than that in the control group, and the two groups differed greatly in this measure at 21 days, with tumor volumes of 823.6 +/- 50.58 mm(3) and 1162.7 +/- 73.08 mm(3) in the (188)Re-DTPA-DG treated and control groups, respectively (p < 0.01).

CONCLUSIONS

(188)Re-DTPA-DG showed excellent tumor targeting and tumor-growth-suppressing effects, and holds promise as an internal agent for tumor radiotherapy.

Synthesis and evaluation of a technetium-99m-labeled diethylenetriaminepentaacetate–deoxyglucose complex ([99mTc]–DTPA–DG) as a potential imaging modality for tumors

This study describes the radiolabeling and preliminary biologic testing of diethylenetriaminepentaacetic acid (DTPA)-deoxyglucose (DG) labeled with (99m)Tc. A one-step [(99m)Tc]-DTPA-DG kit was prepared using the stannous chloride reduction method. When (99m)TcO(4)(-) was added to the DTPA-DG kit at room temperature the radiochemical purity 30 min later was 99.2%, and it remained >98.6% for 6 h. Rapid blood clearance of [(99m)Tc]-DTPA-DG was observed in in vivo biodistribution, the main route of clearance was via the kidneys. No significant accumulation in any other organs was seen. The tumor-to-brain and tumor-to-muscle concentration ratios for [(99m)Tc]-DTPA-DG uptake were higher than those for fluorine-18-flurodeoxyglucose ((18)F-FDG). Scintigraphic results demonstrated the feasibility of [(99m)Tc]-DTPA-DG imaging tumors. The [(99m)Tc]-DTPA-DG complex is a potential imaging agent due to the ideal physical characteristics of the radionuclide, ease of preparation, low cost, early accumulation and the preference for the renal route of excretion.