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Multiple Administrations of 64Cu-ATSM as a Novel Therapeutic Option for Glioblastoma: a Translational Study Using Mice with Xenografts.

ABSTRACT: Glioblastoma is the most aggressive malignant brain tumor in humans and is difficult to cure using current treatment options. Hypoxic regions are frequently found in glioblastoma, and increased levels of hypoxia are associated with poor clinical outcomes of glioblastoma patients. Hypoxia plays important roles in the progression and recurrence of glioblastoma because of drug delivery deficiencies and induction of hypoxia-inducible factor-1? in tumor cells, which lead to poor prognosis. We focused on a promising hypoxia-targeted internal radiotherapy agent, 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM), to address the need for additional treatment for glioblastoma. This compound can target the overreduced state under hypoxic conditions within tumors. Clinical positron emission tomography studies using radiolabeled Cu-ATSM have shown that Cu-ATSM accumulates in glioblastoma and its uptake is associated with high hypoxia-inducible factor-1? expression. To evaluate the therapeutic potential of this agent for glioblastoma, we examined the efficacy of 64Cu-ATSM in mice bearing U87MG glioblastoma tumors. Administration of single dosage (18.5, 37, 74, 111, and 148 MBq) and multiple dosages (37 MBq × 4) of 64Cu-ATSM was investigated. Single administration of 64Cu-ATSM in high-dose groups dose-dependently inhibited tumor growth and prolonged survival, with slight and reverse signs of adverse events. Multiple dosages of 64Cu-ATSM remarkably inhibited tumor growth and prolonged survival. By splitting the dose of 64Cu-ATSM, no adverse effects were observed. Our findings indicate that multiple administrations of 64Cu-ATSM have effective antitumor effects in glioblastoma without side effects, indicating its potential for treating this fatal disease.

SUBMITTER: Yoshii Y

PROVIDER: S-EPMC5697999 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Multiple Administrations of <sup>64</sup>Cu-ATSM as a Novel Therapeutic Option for Glioblastoma: a Translational Study Using Mice with Xenografts.

Yoshii Yukie Y Matsumoto Hiroki H Yoshimoto Mitsuyoshi M Zhang Ming-Rong MR Oe Yoko Y Kurihara Hiroaki H Narita Yoshitaka Y Jin Zhao-Hui ZH Tsuji Atsushi B AB Yoshinaga Keiichiro K Fujibayashi Yasuhisa Y Higashi Tatsuya T

Translational oncology 20171117 1

Glioblastoma is the most aggressive malignant brain tumor in humans and is difficult to cure using current treatment options. Hypoxic regions are frequently found in glioblastoma, and increased levels of hypoxia are associated with poor clinical outcomes of glioblastoma patients. Hypoxia plays important roles in the progression and recurrence of glioblastoma because of drug delivery deficiencies and induction of hypoxia-inducible factor-1α in tumor cells, which lead to poor prognosis. We focused ...[more]

PMID: 29154146

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Project description:BackgroundDiacetyl-bis(N4-methylthiosemicarbazone), labeled with 64Cu (64Cu-ATSM) has been suggested as a promising tracer for imaging hypoxia. However, various controversial studies highlighted potential pitfalls that may disable its use as a selective hypoxic marker. They also highlighted that the results may be tumor location dependent. Here, we first analyzed uptake of Cu-ATSM and its less lipophilic counterpart Cu-Cl2 in the tumor over time in an orthotopic glioblastoma model. An in vitro study was also conducted to investigate the hypoxia-dependent copper uptake in tumor cells. We then further performed a comprehensive ex vivo study to compare 64Cu uptake to hypoxic markers, specific cellular reactions, and also transporter expression.MethodsμPET was performed 14 days (18F-FMISO), 15 days (64Cu-ATSM and 64Cu-Cl2), and 16 days (64Cu-ATSM and 64Cu-Cl2) after C6 cell inoculation. Thereafter, the brains were withdrawn for further autoradiography and immunohistochemistry. C6 cells were also grown in hypoxic workstation to analyze cellular uptake of Cu complexes in different oxygen levels.ResultsIn vivo results showed that Cu-ASTM and Cu-Cl2 accumulated in hypoxic areas of the tumors. Cu-ATSM also stained, to a lesser extent, non-hypoxic regions, such as regions of astrogliosis, with high expression of copper transporters and in particular DMT-1 and CTR1, and also characterized by the expression of elevated astrogliosis. In vitro results show that 64Cu-ATSM showed an increase in the uptake only in severe hypoxia at 0.5 and 0.2% of oxygen while for 64Cu-Cl2, the cell retention was significantly increased at 5% and 1% of oxygen with no significant rise at lower oxygen percentages.ConclusionIn the present study, we show that Cu-complexes undoubtedly accumulate in hypoxic areas of the tumors. This uptake may be the reflection of a direct dependency to a redox metabolism and also a reflection of hypoxic-induced overexpression of transporters. We also show that Cu-ATSM also stained non-hypoxic regions such as astrogliosis.

Project description:BackgroundThe present study proposed a new concept for targeted radionuclide therapy (TRT) to improve the intratumoral distribution of radioactivity using two different radiopharmaceuticals. We examined the efficacy of a combination of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide-based radiopharmaceutical, 64Cu-cyclam-RAFT-c(-RGDfK-)4 (64Cu-RaftRGD, an ?V?3 integrin [?V?3] tracer), and 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM, a supposed tracer for hypoxic metabolism) in a small animal tumor model.ResultsMice with subcutaneous ?V?3-positive U87MG glioblastoma xenografts were used. The intratumoral distribution of a near-infrared dye, Cy5.5-labeled RAFT-c(-RGDfK-)4 (Cy5.5-RaftRGD), 64Cu-RaftRGD, and 64Cu-ATSM was visualized by fluorescence imaging and autoradiography of the co-injected Cy5.5-RaftRGD with 64Cu-RaftRGD or 64Cu-ATSM at 3 h postinjection. Mice were treated with a single intravenous dose of the vehicle solution (control), 18.5 or 37 MBq of 64Cu-RaftRGD or 64Cu-ATSM, or a combination (18.5 MBq of each agent). The tumor volume, tumor cell proliferation, body weight, survival, and tumor and organ uptake of radiopharmaceuticals were assessed. It was shown that Cy5.5-RaftRGD colocalized with 64Cu-RaftRGD and could be used as a surrogate for the radioactive agent. The intratumoral distribution of Cy5.5-RaftRGD and 64Cu-ATSM was discordant and nearly complementary, indicating a more uniform distribution of radioactivity achievable with the combined use of 64Cu-RaftRGD and 64Cu-ATSM. Neither 64Cu-RaftRGD nor 64Cu-ATSM showed significant effects on tumor growth at 18.5 MBq. The combination of both (18.5 MBq each) showed sustained inhibitory effects against tumor growth and tumor cell proliferation and prolonged the survival of the mice, compared to that by either single agent at 37 MBq. Interestingly, the uptake of the combination by the tumor was higher than that of 64Cu-RaftRGD alone, but lower than that of 64Cu-ATSM alone. The kidneys showed the highest uptake of 64Cu-RaftRGD, whereas the liver exhibited the highest uptake of 64Cu-ATSM. No obvious adverse effects were observed in all treated mice.ConclusionsThe combination of 64Cu-RaftRGD and 64Cu-ATSM achieved an improved antitumor effect owing to the more uniform intratumoral distribution of radioactivity. Thus, combining different radiopharmaceuticals to improve the intratumoral distribution would be a promising concept for more effective and safer TRT.

Project description:Therapies targeting reductive/oxidative (redox) metabolism hold potential in cancers resistant to chemotherapy and radiation. A redox imaging marker would help identify cancers susceptible to redox-directed therapies. Copper(II)-diacetyl-bis(4-methylthiosemicarbazonato) (Cu-ATSM) is a PET tracer developed for hypoxia imaging that could potentially be used for this purpose. We aimed to demonstrate that Cu-ATSM signal is dependent on cellular redox state, irrespective of hypoxia. Methods: We investigated the relationship between 64Cu-ATSM signal and redox state in human cervical and colon cancer cells. We altered redox state using drug strategies and single-gene mutations in isocitrate dehydrogenases (IDH1/2). Concentrations of reducing molecules were determined by spectrophotometry and liquid chromatography-mass spectrometry and compared with 64Cu-ATSM signal in vitro. Mouse models of cervical cancer were used to evaluate the relationship between 64Cu-ATSM signal and levels of reducing molecules in vivo, as well as to evaluate the change in 64Cu-ATSM signal after redox-active drug treatment. Results: A correlation exists between baseline 64Cu-ATSM signal and cellular concentration of glutathione, nicotinamide adenine dinucleotide phosphate (NADPH), and nicotinamide adenine dinucleotide (NADH). Altering NADH and NADPH metabolism using drug strategies and IDH1 mutations resulted in significant changes in 64Cu-ATSM signal under normoxic conditions. Hypoxia likewise changed 64Cu-ATSM signal, but treatment of hypoxic cells with redox-active drugs resulted in a more dramatic change than hypoxia alone. A significant difference in NADPH was seen between cervical tumor orthotopic implants in vivo, without a corresponding difference in 64Cu-ATSM signal. After treatment with β-lapachone, there was a change in 64Cu-ATSM signal in xenograft tumors smaller than 50 mg but not in larger tumors. Conclusion: 64Cu-ATSM signal reflects redox state, and altering redox state impacts 64Cu-ATSM metabolism. Our animal data suggest there are other modulating factors in vivo. These findings have implications for the use of 64Cu-ATSM as a predictive marker for redox therapies, though further in vivo work is needed.

Project description:INTRODUCTION:Cardiovascular disease is the leading cause of death in the United States. The identification of vulnerable plaque at risk of rupture has been a major focus of research. Hypoxia has been identified as a potential factor in the formation of vulnerable plaque, and it is clear that decreased oxygen plays a role in the development of plaque angiogenesis leading to plaque destabilization. The purpose of this study is to demonstrate the feasibility of copper-64 labeled diacetyl-bis (N(4)-methylthiosemicarbazone) ((64)Cu-ATSM), a positron-emitting radiopharmaceutical taken up in low-oxygen-tension cells, for the identification of hypoxic and potentially unstable atherosclerotic plaque in a mouse model. METHODS:(64)Cu-ATSM PET was performed in 21 atherosclerotic apolipoprotein E knockout (ApoE(-/-)) mice, 6 of which were fed high-fat diet (HFD) while the others received standard-chow diet (SCD), and 13 control wild type mice fed SCD. 4 SCD ApoE(-/-) mice and 4 SCD wild type mice also underwent (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) imaging one day prior to (64)Cu-ATSM PET. RESULTS:(64)Cu-ATSM uptake was increased in the aortic arch in SCD ApoE(-/-) mice (average aortic arch/muscle (A/M) standardized uptake value ratio 7.5-30min post injection: (5.66±0.23) compared to control mice (A/M SUV ratio 7.5-30min post injection (3.87±0.22), p<0.0001). HFD ApoE(-/-) mice also showed similarly increased aortic arch uptake on PET imaging in comparison to control mice. Immunohistochemistry in both HFD and SCD ApoE(-/-) mice revealed noticeable hypoxia by pimonidazole stain in atherosclerosis which was co-localized to macrophage by CD68 staining. Autoradiography assessment demonstrated the presence of hypoxia by (64)Cu-ATSM uptake correlated with pimonidazole uptake within the ex vivo atherosclerotic aortic arch specimens. A significant increase in (18)F-FDG uptake in the SCD ApoE(-/-) mice in comparison to controls was also observed at delayed time points. CONCLUSION:This pre-clinical study suggests that (64)Cu-ATSM is a potential PET tracer for hypoxia imaging in atherosclerosis. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE:While studies in humans are necessary for conclusive data, in the long term, a (64)Cu-ATSM PET imaging strategy could help facilitate the study of plaque biology in human patients.

Project description:Delta-like ligand 4 (Dll4) expressed in tumor cells plays a key role to promote tumor growth of numerous cancer types. Based on a novel antihuman Dll4 monoclonal antibody (61B), we developed a (64)Cu-labeled probe for positron emission tomography (PET) imaging of tumor Dll4 expression. In this study, 61B was conjugated with the (64)Cu-chelator DOTA through lysine on the antibody. Human IgG (hIgG)-DOTA, which did not bind to Dll4, was also prepared as a control. The Dll4 binding activity of the probes was evaluated through the bead-based binding assay with Dll4-alkaline phosphatase. The resulting PET probes were evaluated in U87MG glioblastoma and HT29 colorectal cancer xenografts in athymic nude mice. Our results demonstrated that the 61B-DOTA retained (77.2 ± 3.7) % Dll4 binding activity of the unmodified 61B, which is significantly higher than that of hIgG-DOTA (0.06 ± 0.03) %. Confocal microscopy analysis confirmed that 61B-Cy5.5, but not IgG-Cy5.5, predominantly located within the U87MG and HT29 cells cytoplasm. U87MG cells showed higher 61B-Cy5.5 binding as compared to HT29 cells. In U87MG xenografts, 61B-DOTA-(64)Cu demonstrated remarkable tumor accumulation (10.5 ± 1.7 and 10.2 ± 1.2%ID/g at 24 and 48 h postinjection, respectively). In HT29 xenografts, tumor accumulation of 61B-DOTA-(64)Cu was significantly lower than that of U87MG (7.3 ± 1.3 and 6.6 ± 1.3%ID/g at 24 and 48 h postinjection, respectively). The tumor accumulation of 61B-DOTA-(64)Cu was significantly higher than that of hIgG-DOTA-(64)Cu in both xenografts models. Immunofluorescence staining of the tumor tissues further confirmed that tumor accumulation of 61B-Cy5.5 was correlated well with in vivo PET imaging data using 61B-DOTA-(64)Cu. In conclusion, 61B-DOTA-(64)Cu PET probe was successfully synthesized and demonstrated prominent tumor uptake by targeting Dll4. 61B-DOTA-(64)Cu has great potential to be used for noninvasive Dll4 imaging, which could be valuable for tumor detection, Dll4 expression level evaluation, and Dll4-based treatment monitoring.

Dataset Information

Multiple Administrations of 64Cu-ATSM as a Novel Therapeutic Option for Glioblastoma: a Translational Study Using Mice with Xenografts.

Publications

Multiple Administrations of <sup>64</sup>Cu-ATSM as a Novel Therapeutic Option for Glioblastoma: a Translational Study Using Mice with Xenografts.

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