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Supplementary Files contain (1) Supplementary Materials and Methods for �V�3 expression analysis, autoradiography and histological analysis, and hematology and hepatorenal function; (2) Supplementary Tables S1-S5; and (3) Supplementary Figures S1-S5. Table S1Effects of 37 MBq (1 nmol) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 {plus minus} GF/Lys on hepatorenal functions of U87MG tumor-bearing mice; Table S2Blood cell counts of U87MG tumor-bearing mice at various time points post-injection of 37 MBq (1 nmol) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 {plus minus} GF/Lys; Table S3Blood cell counts of U87MG tumor-bearing mice at various time points after single dose administrations of 37 and 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Table S4Effects of 74 MBq (2 nmol) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 + GF/Lys on hepatorenal functions of normal mice; Table S5Human absorbed doses extrapolated from the biodistribution data of 64Cu-cyclam-RAFT-c(-RGDfK-)4 in U87MG tumor-bearing mice

Figure S1The treatment outcomes of radiotherapy with 37 MBq (1 nmol) of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Figure S2Toxicity studies in normal mice that were injected with 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Figure S3Preliminary study of U87MG tumors excised at day 13 p.i. of 37 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4 for the changes in microvasculature; Figure S4Positive correlation between the tumor volume and the corresponding WBC in U87MG tumor-bearing mice; Figure S5Biodistribution of 64Cu-cyclam-RAFT-c(-RGDfK-)4 at various peptide doses (0.00510 nmol) in U87MG tumor-bearing mice.

The files contain (1) Supplementary Materials and Methods for αVβ3 expression analysis, autoradiography and histological analysis, and hematology and hepatorenal function; (2) Supplementary Tables S1-S5; and (3) Supplementary Figures S1-S5. Table S1â^'Effects of 37 MBq (1 nmole) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 {plus minus} GF/Lys on hepatorenal functions of U87MG tumor-bearing mice; Table S2â^'Blood cell counts of U87MG tumor-bearing mice at various time points post-injection of 37 MBq (1 nmole) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 {plus minus} GF/Lys; Table S3â^'Blood cell counts of U87MG tumor-bearing mice at various time points after single dose administrations of 37 and 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Table S4â^'Effects of 74 MBq (2 nmole) of 64Cu-cyclam-RAFT-c(-RGDfK-)4 + GF/Lys on hepatorenal functions of normal mice; Table S5â^'Human absorbed doses extrapolated from the biodistribution data of 64Cu-cyclam-RAFT-c(-RGDfK-)4 in U87MG tumor-bearing mice; Figure S1â^'The treatment outcomes of radiotherapy with 37 MBq (1 nmole) of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Figure S2â^'Toxicity studies in normal mice that were injected with 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4; Figure S3â^'Preliminary study of U87MG tumors excised at day 13 p.i. of 37 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4 for the changes in microvasculature; Figure S4â^'Positive correlation between the tumor volume and the corresponding WBC in U87MG tumor-bearing mice; Figure S5â^'Biodistribution of 64Cu-cyclam-RAFT-c(-RGDfK-)4 at various peptide doses (0.005â^'10 nmole) in U87MG tumor-bearing mice.

We developed a human-scale single-ring OpenPET (SROP) system, which had an open space allowing us access to the subject during measurement. The SROP system consisted of 160 4-layer depth-of-interaction detectors. The open space with the axial width of 430 mm was achieved with the ring axial width of 214 mm and the ring inner diameter of 660 mm. The detectors were axially shifted to each other so that the detector ring was aligned along a plane horizontally tilted by 45° against the axial direction. The system was developed as a mobile scanner to be used not only in clinical positron emission tomography (PET) rooms but also in charged-particle therapy treatment rooms as well as animal experiment rooms. Almost uniform spatial resolution better than 3 mm throughout the entire field of view (FOV) was realized with an iterative image reconstruction method. Peak absolute sensitivity was 3.1%, and there was a region with sensitivity better than 0.8% for a length of more than 700 mm. An in-beam imaging experiment conducted at the heavy ion medical accelerator in Chiba showed that the system was operable even at the highest beam intensity available for heavy-ion therapy. In addition, we conducted entire-body monkey dynamic imaging utilizing the long region inside the gantry by positioning a monkey along the direction having the longest FOV tilted by 45° against the axial direction. We concluded the developed system has a capability to realize versatile PET applications by utilizing its wide-open space and mobility in addition to high spatial resolution with sufficiently good sensitivity. -9mm]Please consider rephrasing the sentence “We concluded the developed system” for clarity.

Breast positron emission tomography (PET) has had insurance coverage when performed with conventional whole-body PET in Japan since 2013. Together with whole-body PET, accurate examination of breast cancer and diagnosis of metastatic disease are possible, and are expected to contribute significantly to its treatment planning. To facilitate a safer, smoother, and more appropriate examination, the Japanese Society of Nuclear Medicine published the first edition of practice guidelines for high-resolution breast PET in 2013. Subsequently, new types of breast PET have been developed and their clinical usefulness clarified. Therefore, the guidelines for breast PET were revised in 2019. This article updates readers as to what is new in the second edition. This edition supports two different types of breast PET depending on the placement of the detector: the opposite-type (positron emission mammography; PEM) and the ring-shaped type (dedicated breast PET; dbPET), providing an overview of these scanners and appropriate imaging methods, their clinical applications, and future prospects. The name “dedicated breast PET” from the first edition is widely used to refer to ring-shaped type breast PET. In this edition, “breast PET” has been defined as a term that refers to both opposite- and ring-shaped devices. Up-to-date breast PET practice guidelines would help provide useful information for evidence-based breast imaging.

Transplantation of human‐induced pluripotent stem cell‐derived neural stem/progenitor cells (hiPSC‐NS/PCs) is a promising treatment for a variety of neuropathological conditions. Although previous reports have indicated the effectiveness of hiPSC‐NS/PCs transplantation into the injured spinal cord of rodents and nonhuman primates, long‐term observation of hiPSC‐NS/PCs post‐transplantation suggested some “unsafe” differentiation‐resistant properties, resulting in disordered overgrowth. These findings suggest that, even if “safe” NS/PCs are transplanted into the human central nervous system (CNS), the dynamics of cellular differentiation of stem cells should be noninvasively tracked to ensure safety. Positron emission tomography (PET) provides molecular‐functional information and helps to detect specific disease conditions. The current study was conducted to visualize Nestin (an NS/PC marker)‐positive undifferentiated neural cells in the CNS of immune‐deficient (nonobese diabetic‐severe combined immune‐deficient) mice after hiPSC‐NS/PCs transplantation with PET, using 18 kDa translocator protein (TSPO) ligands as labels. TSPO was recently found to be expressed in rodent NS/PCs, and its expression decreased with the progression of neuronal differentiation. We hypothesized that TSPO would also be present in hiPSC‐NS/PCs and expressed strongly in residual immature neural cells after transplantation. The results showed high levels of TSPO expression in immature hiPSC‐NS/PCs‐derived cells, and decreased TSPO expression as neural differentiation progressed in vitro. Furthermore, PET with [18F] FEDAC (a TSPO radioligand) was able to visualize the remnant undifferentiated hiPSC‐NS/PCs‐derived cells consisting of TSPO and Nestin+ cells in vivo. These findings suggest that PET with [18F] FEDAC could play a key role in the safe clinical application of CNS repair in regenerative medicine., By utilizing the characteristic of neural stem/progenitor cells (NS/PCs) to express translocator protein (TSPO), positron emission tomography (PET) with TSPO ligand was able to visualize residual immature neural cells after NS/PCs transplantation.

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 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-1α 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.

// Yukie Yoshii 1 , Mitsuyoshi Yoshimoto 2 , Hiroki Matsumoto 3 , Takako Furukawa 1, 4 , Ming-Rong Zhang 1 , Masayuki Inubushi 5 , Atsushi B. Tsuji 1 , Yasuhisa Fujibayashi 1 , Tatsuya Higashi 1 and Tsuneo Saga 1, 6 1 National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan 2 Division of Functional Imaging, National Cancer Center Hospital East, Kashiwa, Japan 3 Research Centre, Nihon Medi-Physics Co., Ltd., Sodegaura, Japan 4 Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan 5 Department of Nuclear Medicine, Kawasaki Medical School, Kurashiki, Japan 6 Department of Diagnostic Radiology, Kyoto University Hospital, Kyoto, Japan Correspondence to: Yukie Yoshii, email: yoshii.yukie@qst.go.jp Keywords: 64 Cu-ATSM, angiogenesis, bevacizumab, hypoxia, vascular decrease Received: July 19, 2017 Accepted: August 17, 2017 Published: September 28, 2017 ABSTRACT Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, is an antiangiogenic agent clinically used for various cancers. However, repeated use of this agent leads to tumor-decreased vascularity and hypoxia with activation of an HIF-1 signaling pathway, which results in drug delivery deficiency and induction of malignant behaviors in tumors. Here, we developed a novel strategy to treat tumors with bevacizumab-induced vascular decrease and hypoxia using 64 Cu-diacetyl-bis ( N 4 -methylthiosemicarbazone) ( 64 Cu-ATSM), a potential theranostic agent, which possesses high tissue permeability and can target over-reduced conditions under hypoxia in tumors, with a human colon carcinoma HT-29 tumor-bearing mouse model. The long-term treatment with bevacizumab caused decreased blood vessel density and activation of an HIF-1 signaling pathway; increased uptake of 64 Cu-ATSM was also observed despite limited blood vessel density in HT-29 tumors. In vivo high-resolution SPECT/PET/CT imaging confirmed reduced vascularity and increased proportion of 64 Cu-ATSM uptake areas within the bevacizumab-treated tumors. 64 Cu-ATSM therapy was effective to inhibit tumor growth and prolong survival of the bevacizumab-treated tumor-bearing mice without major adverse effects. In conclusion, 64 Cu-ATSM therapy effectively enhanced anti-tumor effects in tumors with bevacizumab-induced vascular decrease and hypoxia. 64 Cu-ATSM therapy could represent a novel approach as an add-on to antiangiogenic therapy.

Copper-67 (Cu) is one of the most promising radionuclides for internal radiation therapy. Globally, several projects have recently been initiated for developing innovative approaches for the large-scale production of Cu. Encouraged by these, we performed Cu-radiolabeling of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide conjugate, cyclam-RAFT-c(-RGDfK-)4, which selectively targets αVβ3 integrin (αVβ3), the transmembrane receptor involved in tumor invasion, angiogenesis, and metastasis. We also evaluated the therapeutic potential and safety of this radiocompound.Cu, produced through the Ni(α, p)Cu reaction, was used for the radiolabeling of cyclam-RAFT-c(-RGDfK-)4 at 70°C for 10 min. The radiolabeling efficiency and product stability were assessed using reversed-phase high-performance liquid chromatography and/or thin-layer chromatography. Mice with subcutaneous αVβ3-positive U87MG-glioblastoma xenografts received a single intravenous injection of one of the following: Cu-cyclam-RAFT-c(-RGDfK-)4 (11.1 MBq), peptide control, or vehicle solution. The tumor volumes were measured, side effects were assessed in terms of body weight, routine hematology, and hepatic and renal functions, and the mouse radiation dosimetry was estimated.Cu-cyclam-RAFT-c(-RGDfK-)4 was produced with a radiochemical purity of 97.9±2.4% and a specific activity of 2.7±0.6 MBq/nmol and showed high in-vitro and in-vivo plasma stability. The administration of a single dose of Cu-cyclam-RAFT-c(-RGDfK-)4 resulted in significant tumor growth delay in comparison with that observed upon vehicle or peptide control administration, with an estimated tumor-absorbed dose of 0.712 Gy. No significant toxicity was observed in Cu-cyclam-RAFT-c(-RGDfK-)4-treated mice.Cu-cyclam-RAFT-c(-RGDfK-)4 would be a promising therapeutic agent for αVβ3 integrin-targeted internal radiotherapy.

Hypoxia in tumors is known to contribute to the malignant characteristics such as therapy resistance and metastatic potential. Cu-diacetyl-bis (N4-methylthiosemicarbazone) (Cu-ATSM), labeled with several Cu radioisotopes (60Cu, 62Cu and 64Cu) is a potential PET imaging agent that targets tumor hypoxia with over-reduced conditions. Clinical studies of Cu-ATSM PET has been conducted worldwide in recent years and the usefulness of this agent is being recognized. Multicenter clinical study of 62Cu-ATSM PET has been conducted in Japan. Among Cu-ATSM tracers, 64Cu-ATSM can be used not only as a PET imaging agent but also as a therapeutic agent, because 64Cu emits β− particle and Auger electron, which can damage the cells. Here, we will discuss the present status and future prospects of Cu-ATSM.

Radiochemical conversion is an important term to be included in the "Consensus nomenclature rules for radiopharmaceutical chemistry". Radiochemical conversion should be used to define reaction efficiency by measuring the transformation of components in a crude reaction mixture at a given time, whereas radiochemical yield is better suited to define the efficiency of an entire reaction process including, for example, separation, isolation, filtration, and formulation.

Colon cancer is one of the leading causes of cancer death worldwide. Adjuvant chemotherapy following primary surgical treatment is suggested to be beneficial in eradicating invisible disseminated small tumors in colon cancer; however, an effective drug remains to be developed. Recently, we reported a novel drug screening system using a nanoimprinting 3-dimensional (3D) culture that creates multicellular spheroids, which simulate in vivo conditions and, thereby, predict effective drugs in vivo. This study aimed to perform drug selection using our recently developed 3D culture system in a human colon cancer HCT116 cell line stably expressing red fluorescent protein (HCT116-RFP), to determine the most effective agent in a selection of clinically used antitumor agents for colon cancer. In addition, we confirmed the efficacy of the selected drug regorafenib, in vivo using a mouse model of disseminated small tumors. HCT116-RFP cells were cultured using a nanoimprinting 3D culture and in vitro drug selection was performed with 8 clinically used drugs [bevacizumab, capecitabine, cetuximab, 5-fluorouracil (5-FU), irinotecan, oxaliplatin, panitumumab and regorafenib]. An in vivo study was performed in mice bearing HCT116-RFP intraperitoneally disseminated small tumors using 3'-[18F]-fluoro-3'-deoxythymidine-positron emission tomography and fluorescence microscopy imaging to evaluate the therapeutic effects. Regorafenib was determined to be the most effective drug in the 3D culture, and significantly inhibited tumor growth in vivo, compared to the untreated control and 5-FU-treated group. The drug 5-FU is commonly used in colon cancer treatment and was used as a reference. Our results demonstrate that regorafenib is a potentially efficacious adjuvant chemotherapeutic agent for the treatment of disseminated small colon cancer and, therefore, warrants further preclinical and clinical studies.

The prognostic value of positron emission tomography/computed tomography (PET/CT) with 18F-fluoroazomycin arabinoside (FAZA) was evaluated in patients with head and neck squamous cell carcinoma (HNSCC) who underwent chemoradiotherapy (CRT). Twenty-nine patients with head and neck cancer underwent FAZA PET/CT before treatment. Data acquisition started 2 h after FAZA administration. In 26 patients with squamous cell carcinoma, FAZA uptakes by the primary lesions (tumor–muscle ratio in primary lesion: Pr T/M) and by the lymph node metastases (tumor–muscle ratio in lymph node metastasis) were compared with various clinical parameters. For the HNSCC patients who completed CRT protocol (n = 23), those who experienced disease progression were compared with those who did not experience disease progression with respect to the clinical and PET parameters. The prognostic values of the clinical and PET parameters were then evaluated with regard to progression-free survival (PFS). Pr T/M positively correlated with the lesion’s maximum diameter, and it was significantly higher in stage IV lesions compared with stage I–III lesions. No significant differences were observed between the patients who experienced disease progression and those who did not, with respect to the clinical parameters. The average Pr T/M tended to be higher in patients with disease progression, although the differences were not statistically significant (p = 0.086). Kaplan–Meier analysis with log-rank tests indicated that Pr T/M was an only significant predictor of PFS among PET and clinical parameters evaluated (p = 0.010). FAZA uptake by the primary lesion was a significant prognostic indicator in HNSCC patients undergoing CRT. Hence, FAZA PET/CT may provide useful information in the management of HNSCC patients treated with CRT. Registration number of clinical trial’s registry: UMIN000003440.

Background The 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 αVβ3 integrin [αVβ3] tracer), and 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM, a supposed tracer for hypoxic metabolism) in a small animal tumor model. Results Mice with subcutaneous αVβ3-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. Conclusions The 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. Electronic supplementary material The online version of this article (10.1186/s13550-018-0407-3) contains supplementary material, which is available to authorized users.

Open letter to journal editors on : International Consensus Radiochemistry Nomenclature Guidelines

Over recent years, within the community of radiopharmaceutical sciences, there has been an increased incidence of incorrect usage of established scientific terms and conventions, and even the emergence of ‘self-invented’ terms. In order to address these concerns, an international Working Group on ‘Nomenclature in Radiopharmaceutical Chemistry and related areas’ was established in 2015 to achieve clarification of terms and to generate consensus on the utilisation of a standardised nomenclature pertinent to the field. Upon open consultation, the following consensus guidelines were agreed, which aim to: • Provide a reference source for nomenclature good practice in the radiopharmaceutical sciences.• Clarify the use of terms and rules concerning exclusively radiopharmaceutical terminology, i.e. nuclear- and radiochemical terms, symbols and expressions.• Address gaps and inconsistencies in existing radiochemistry nomenclature rules.• Provide source literature for further harmonisation beyond our immediate peer group (publishers, editors, IUPAC, pharmacopoeias, etc.).

Radioactive copper (II) (diacetyl-bis N4-methylthiosemicarbazone) (Cu-ATSM) isotopes were originally developed for the imaging of hypoxia in tumors. Because the decay of a (64)Cu atom is emitting not only positrons but also Auger electrons, this radionuclide has great potential as a theranostic agent. However, the success of (64)Cu-ATSM internal radiation therapy would depend on the contribution of Auger electrons to tumor cell killing. Therefore, we designed a cell culture system to define the contributions to cell death from Auger electrons to support or refute our hypothesis that the majority of cell death from (64)Cu-ATSM is a result of high-LET Auger electrons and not positrons or other low-LET radiation. Chinese hamster ovary (CHO) wild type and DNA repair-deficient xrs5 cells were exposed to (64)Cu-ATSM during hypoxic conditions. Surviving fractions were compared with those surviving gamma-radiation, low-LET hadron radiation, and high-LET heavy ion exposure. The ratio of the D(10) values (doses required to achieve 10% cell survival) between CHO wild type and xrs5 cells suggested that (64)Cu-ATSM toxicity is similar to that of high-LET Carbon ion radiation (70 keV/μm). γH2AX foci assays confirmed DNA double-strand breaks and cluster damage by high-LET Auger electrons from (64)Cu decay, and complex types of chromosomal aberrations typical of high-LET radiation were observed after (64)Cu-ATSM exposure. The majority of cell death was caused by high-LET radiation. This work provides strong evidence that (64)Cu-ATSM damages DNA via high-LET Auger electrons, supporting further study and consideration of (64)Cu-ATSM as a cancer treatment modality for hypoxic tumors.

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 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-1α 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.

To maintain sterility of PET drug is the most important for in-house positron emission tomography (PET) drug manufacturing, and sanitary control of the laboratory to perform aseptic procedure is the key point for the sterility of PET drugs. However, rigorous sanitary control affects both the high cost and the low efficiency. To conquer those, we developed an isolator system especially for PET drug compounding including sterilization and dispensing units. This system consists of a HEPA unit for inlet and outlet, positive regulation of the ear inside isolator, a sterilizer with vapored hydrogen peroxide and a dispenser with self-shield for radiation. We set the materials for the dispenser through gloves, and the compounding such as sterilization and dispensing PET drugs to the containers is performed automatically without radiation. High level assurance of PET drug sterility is expected to be accomplished in the PET centers of the hospitals without high level sanitary control.

Introduction The intratumoral distributions of [ 18 F]FDG and [ 64 Cu]Cu-ATSM have been reported to be similar in adenocarcinomas but different in squamous cell carcinoma (SCC) in clinical studies. In the present study, we compared the intratumoral distributions of these two tracers in cancer tissue originated spheroid (CTOS) xenografts derived from adenocarcinoma and SCC, which retain the histological characteristics of the original tumors, and in cancer cell line xenografts of corresponding origin, to investigate the underlying mechanism of the distinct FDG and Cu-ATSM distribution patterns in adenocarcinoma and SCC. Methods CTOSs derived from colon adenocarcinoma and lung SCC and cell lines established from colon adenocarcinoma and lung SCC, which were used for comparison, were subcutaneously transplanted into immunodeficient mice. One hour after administering [ 14 C]FDG and [ 64 Cu]Cu-ATSM, the intratumoral distributions were compared in the xenografts by using dual-tracer autoradiography. Adjacent sections were evaluated for necrosis, vasculature anatomy, Ki-67 antigen, and pimonidazole adducts using hematoxylin and eosin and immunohistochemical staining. Results There was a higher regional overlap of high FDG and Cu-ATSM accumulations in the adenocarcinoma CTOS xenografts than in the SCC CTOS xenografts, while the overlap in the adenocarcinoma cell line xenograft was lower than that observed in the SCC cell line. High FDG accumulation occurred primarily in proximity to necrotic or pimonidazole adduct positive regions, while high Cu-ATSM accumulation occurred primarily in live cell regions separate from the necrotic regions. The adenocarcinoma CTOS xenograft had the stereotypical glandular structure, resulting in more intricately mixed regions of live and necrotic cells compared to those observed in the SCC CTOS or the cell line xenografts. Conclusion Tumor morphological characteristics, specifically the spatial distribution of live and necrotic cell regions, appeared to be one of the most critical factors determining the regional overlap of FDG and Cu-ATSM distributions in adenocarcinoma.

(64)Cu-cyclam-RAFT-c(-RGDfK-)4, an αVβ3 integrin-targeting tetrameric cyclic RGD peptide probe, is a potential theranostic compound for positron emission tomography (PET) of tumor angiogenesis and for internal radiotherapy owing to the multiple decay modes of (64)Cu. Since kidneys are dose-limiting organs in internal radiotherapy, we aimed to reduce the renal accumulation of (64)Cu-cyclam-RAFT-c(-RGDfK-)4 by co-injection with Gelofusine (GF), a succinylated gelatin solution, and/or L-lysine (Lys), and to explore, for the first time, the related mechanisms using the noninvasive and quantitative PET imaging technology. Biodistribution assays, dynamic and static PET scans, and metabolism studies with radio-thin-layer chromatography (radio-TLC) were performed in healthy or αVβ3-positive tumor-bearing mice. In the results, co-injection with GF markedly reduced the renal uptake and slightly increased the tumor uptake of (64)Cu-cyclam-RAFT-c(-RGDfK-)4. L-Lysine alone had no effect on the probe biodistribution, but the combined use of Lys and GF tended to enhance the effect of GF. Dynamic PET and metabolite analysis by radio-TLC highly revealed that GF blocks the renal reabsorption of (64)Cu-cyclam-RAFT-c(-RGDfK-)4, but does not interfere with its metabolism and excretion. In conclusion, administration of GF and Lys is a useful strategy for kidney protection in (64)Cu-cyclam-RAFT-c(-RGDfK-)4-based internal radiotherapy.

Introduction [ 18 F]FEDAC ([ 18 F] 1 ) has potent binding affinity and selectivity for translocator protein (18kDa, TSPO), and has been used to noninvasively visualize neuroinflammation, lung inflammation, acute liver damage, nonalcoholic fatty liver disease, and liver fibrosis. We had previously synthesized [ 18 F] 1 in two steps: (i) preparation of [ 18 F]fluoroethyl bromide and (ii) coupling of [ 18 F]fluoroethyl bromide with the appropriate precursor ( 2 ) for labeling. In this study, to clinically utilize [ 18 F] 1 as a PET radiopharmaceutical and to transfer the production technique of [ 18 F] 1 to other PET centers, we simplified its preparation by using a direct, one-step, tosyloxy-for-fluorine substitution. We also performed an acute toxicity study as a major non-clinical safety test, and determined radiometabolites using human liver microsomes. Methods [ 18 F] 1 was prepared via direct 18 F-fluorination by heating the corresponding tosylated derivative ( 3 ) with [ 18 F]fluoride as its Kryptofix 222 complex in dimethyl sulfoxide at 110°C for 15min, following by HPLC purification. Non-clinical safety tests were performed for the extended single-dose toxicity study in rats, and for the in vitro metabolite analysis with human liver microsomal incubation. Results High quality batches of [ 18 F] 1 , compatible with clinical applications, were obtained. At the end of irradiation, the decay-corrected radiochemical yield of [ 18 F] 1 using 1 and 5mg of precursor based on [ 18 F]fluoride was 18.5±7.9% ( n =10) and 52.0±5.8% ( n =3), respectively. A single-dose of [ 18 F] 1 did not show toxicological effects for 14 days after the injection in male and female rats. In human liver microsomal incubations, [ 18 F] 1 was easily metabolized to [ 18 F]desbenzyl-FEDAC ([ 18 F] 10 ) by CYPs (4.2% of parent compound left 60min after incubation). Conclusion We successfully synthesized clinical grade batches of [ 18 F] 1 and verified the absence of innocuity of this radiotracer. [ 18 F] 1 will be used to first-in-human studies in our facility.

The transmembrane cell adhesion receptor αVβ3 integrin (αVβ3) has been identified as an important molecular target for cancer imaging and therapy. We have developed a tetrameric cyclic RGD (Arg-Gly-Asp) peptide–based radiotracer 64Cu-cyclam-RAFT-c(-RGDfK-)4, which successfully captured αVβ3-positive tumors and angiogenesis by PET. Here, we subsequently evaluated its therapeutic potential and side effects using an established αVβ3-positive tumor mouse model. Mice with subcutaneous U87MG glioblastoma xenografts received single administrations of 37 and 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4 (37 MBq/nmol), peptide control, or vehicle solution and underwent tumor growth evaluation. Side effects were assessed in tumor-bearing and tumor-free mice in terms of body weight, routine hematology, and hepatorenal functions. Biodistribution of 64Cu-cyclam-RAFT-c(-RGDfK-)4 with ascending peptide doses (0.25–10 nmol) and with the therapeutic dose of 2 nmol were determined at 3 hours and at various time points (2 minutes–24 hours) postinjection, respectively, based on which radiation-absorbed doses were estimated. The results revealed that 64Cu-cyclam-RAFT-c(-RGDfK-)4 dose dependently slowed down the tumor growth. The mean tumor doses were 1.28 and 1.81 Gy from 37 and 74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4, respectively. Peptide dose study showed that the tumor uptake of 64Cu-cyclam-RAFT-c(-RGDfK-)4 dose dependently decreased at doses ≥1 nmol, indicating a saturation of αVβ3 with the administered therapeutic doses (1 and 2 nmol). Combined analysis of the data from tumor-bearing and tumor-free mice revealed no significant toxicity caused by 37–74 MBq of 64Cu-cyclam-RAFT-c(-RGDfK-)4. Our study demonstrates the therapeutic efficacy and safety of 64Cu-cyclam-RAFT-c(-RGDfK-)4 for αVβ3-targeted radionuclide therapy. 64Cu-cyclam-RAFT-c(-RGDfK-)4 would be a promising theranostic drug for cancer imaging and therapy. Mol Cancer Ther; 15(9); 2076–85. ©2016 AACR.

(64)Cu-diacetyl-bis (N(4)-methylthiosemicarbazone) ((64)Cu-ATSM) is a potential theranostic agent targeting the over-reduced state under hypoxia within tumors. Recent clinical Cu-ATSM positron emission tomography studies have revealed a correlation between uptake and poor prognosis; however, the reason is unclear. Here, using a human colon carcinoma HT-29 model, we demonstrated that the intratumoral (64)Cu-ATSM high-uptake regions exhibited malignant characteristics, such as upregulated DNA repair and elevated %CD133(+) cancer stem-like cells. Based on this evidence, we developed a strategy to enhance the efficacy of (64)Cu-ATSM internal radiotherapy (IRT) by inhibiting DNA repair with a nucleic acid (NA) antimetabolite. The results of the analyses showed upregulation of pathways related to DNA repair along with NA incorporation (bromodeoxyuridine uptake) and elevation of %CD133(+) cells in (64)Cu-ATSM high-uptake regions. In an in vivo(64)Cu-ATSM treatment study, co-administration of an NA antimetabolite and (64)Cu-ATSM synergistically inhibited tumor growth, with little toxicity, and effectively reduced %CD133(+) cells. (64)Cu-ATSM therapy targeted malignant tumor regions with activated DNA repair and high concentrations of CD133(+) cells in the HT-29 model. NA antimetabolite co-administration can be an effective approach to enhance the therapeutic effect of (64)Cu-ATSM IRT.

Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energy states below that of singlet oxygen, such as -carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.

Two-dimensional (2D) cell cultures are essential for drug development and tumor research. However, the limitations of 2D cultures are widely recognized, and a better technique is needed. Recent studies have indicated that a strong physical contact between cells and 2D substrates induces cellular characteristics that differ from those of tumors growing in vivo. 3D cell cultures using various substrates are then developing; nevertheless, conventional approaches have failed in maintenance of cellular proliferation and viability, uniformity, reproducibility, and/or simplicity of these assays. Here, we developed a 3D culture system with inorganic nanoscale scaffolding using nanoimprinting technology (nano-culture plates), which reproduced the characteristics of tumor cells growing in vivo. Diminished cell-to-substrate physical contact facilitated spontaneous tumor cell migration, intercellular adhesion, and multi-cellular 3D-spheroid formation while maintaining cellular proliferation and viability. The resulting multi-cellular spheroids formed hypoxic core regions similar to tumors growing in vivo. This technology allows creating uniform and highly-reproducible 3D cultures, which is easily applicable for microscopic and spectrophotometric assays, which can be used for high-throughput/high-content screening of anticancer drugs and should accelerate discovery of more effective anticancer therapies.

The diagnosis of infection and the ability to distinguish bacterial infection from nonbacterial inflammation by positron emission tomography (PET) have gained interest in recent years, but still few specific radiopharmaceuticals are available for use. In this study, we developed a new radiosynthesis method of 2-deoxy-2-[(18)F]fluoroacetamido-d-glucopyranose ([(18)F]FAG) by applying microwave irradiation and demonstrated that [(18)F]FAG could be a potential radiopharmaceutical to distinguish bacterial infection from nonbacterial inflammation.1,3,4,6-Tetra-O-acetyl-2-deoxy-2-bromoacetamido-d-glucopyranose was used as precursor, and labeling was performed under microwave irradiation conditions followed by alkaline hydrolysis and high-performance liquid chromatography (HPLC) purification. In vitro uptake of [(18)F]FAG by Escherichia coli was performed. Tissue biodistribution of [(18)F]FAG was performed in mice. Moreover, PET imaging acquisition of E. coli infection and nonbacterial inflammation models was performed in rats. Tissue radiotracer-accumulated sites were analyzed by hematoxylin and eosin staining and anti-E.coli immunostaining.The radiosynthesis of [(18)F]FAG was achieved with microwave irradiation, and the radiochemical yield was 9.7%±2.8% end of bombardment (EOB); the radiochemical purity was more than 98%, and the total synthesis time was 62 min. Compared with control group, in vitro uptake of [(18)F]FAG by E. coli was significantly decrease in inhibition group (P.05). Biodistribution studies in mice showed rapid clearance of [(18)F]FAG from the animal body. [(18)F]FAG clearly visualized the infection areas but not nonbacterial inflammation areas in PET studies. Quantitative analysis revealed that the uptake of [(18)F]FAG into infection areas was significantly higher than that of [(18)F]FAG into inflammation areas (P.05). Histological analysis demonstrated the presence of bacterial cells at the sites of accumulation of [(18)F]FAG.Using 1,3,4,6-tetra-O-acetyl-2-deoxy-2-bromoacetamido-d-glucopyranose as a precursor, the new radiosynthesis method of [(18)F]FAG was achieved in fewer steps and with a shorter synthesis time than previously reported. Furthermore, [(18)F]FAG was able to distinguish bacterial infection from nonbacterial inflammation.

Hypoxia is known to have been related with angiogenesis and glycolysis, and may have an influence on tumor treatment effect. Because glucose utilization is higher in malignant cells than that in normal cells, dynamic glucose metabolism of tumor has been evaluated by means of [(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET). To investigate the significance of tumor vascularization in oral squamous cell carcinoma, we compared tumor angiogenesis with the FDG-PET findings. Twenty patients underwent FDG-PET. For the quantitative evaluation of FDG uptake in each tumor, the mean standardized uptake value (SUV) was calculated. Microvessel structures labeled with CD34 antigen were investigated in pretreatment biopsy specimens. Using an image analyzer, we calculated the following microvessel parameters: the ratio of the total number of microvessels (TN) to tumor area (TA), the ratio of the total microvessel perimeter (TP) to the TA, and the ratio of the tumor tissue area more than 150 μm distant from each microvessel (hypoxic ratio, %). The SUV was compared with the above parameters. Simple regression analysis revealed a statistical significance between the SUV and the TN:TA ratio (p = 0.046), as well as between the SUV and the TP:TA ratio (p = 0.0206). The SUV was found to be inversely related to the TN:TA and TP:TA ratios. Elevated glucose metabolism assessed by FDG-PET correlated with reduced vascularization. Higher glucose metabolism might therefore reflect a state of hypoxia.

Introduction The α V β 3 integrin is a well-known transmembrane receptor involved in tumor invasion, angiogenesis and metastasis. Our aim was to evaluate a novel positron emission tomography (PET) probe, 64 Cu-cyclam-RAFT-c(-RGDfK-) 4 , for noninvasive visualization and quantification of α V β 3 integrin expression. Methods RAFT-c(-RGDfK-) 4 , a tetrameric cyclic Arg-Gly-Asp (RGD)-based peptide, was conjugated with a bifunctional chelator, 1,4,8,11-tetraazacyclotetradecane (cyclam), radiolabeled with the positron emitter 64 Cu and evaluated in vitro by cell binding and competitive inhibition assays and in vivo by biodistribution and receptor blocking studies, and PET imaging. The following cell lines, human embryonic kidney HEK293(β 1 ) [α V β 3 -negative] and HEK293(β 3 ) [α V β 3 -overexpressing] and human glioblastoma U87MG [naturally expressing α V β 3 ], together with their subcutaneous xenografts in athymic nude mice, were used for the present study. The expression levels of α V β 3 on these cell lines and tumor xenografts were analyzed by flow cytometry and sodium dodecyl sulfate–polyacrylamide gel electrophoresis/autoradiography, respectively. Results 64 Cu-cyclam-RAFT-c(-RGDfK-) 4 demonstrated the in vitro and in vivo specificity for the α V β 3 integrin and displayed rapid blood clearance, predominantly renal excretion and low uptake in nontumor tissues. Tumor uptake of 64 Cu-cyclam-RAFT-c(-RGDfK-) 4 (3 h postinjection) in HEK293(β 3 ) (high levels of α V β 3 ), U87MG (moderate levels of α V β 3 ) and HEK293(β 1 ) (undetectable levels of α V β 3 ) tumors was 9.35%±1.19%, 3.46%±0.45% and 1.18%±0.30% injected dose per gram, respectively, with a strong and positive correlation with the tumor α V β 3 expression levels (correlation coefficient=0.967; P V β 3 -positive tumors were clearly visualized with high tumor-to-background contrast, and agreed well with the biodistribution results. Conclusion 64 Cu-cyclam-RAFT-c(-RGDfK-) 4 exhibits potential for noninvasively quantifying α V β 3 expression.

Background and objective: The value of dual-time- point 18F-FDG PET was investigated to predict the prognosis of patients with pulmonary sarcoidosis. Methods: Twenty-one patients with pulmonary sarcoidosis underwent 18F-FDG PET examinations at two time points: an early scan at 60 min and a delayed scan at 180 min after injection of 18F-FDG. Standardized uptake values (SUVs) at the two time points and the retention index (RI-SUV) calculated from these were evaluated. To evaluate disease progression, all patients underwent chest CT 1 year after 18F-FDG PET. Using these results, the accuracy of 18F-FDG PET parameters and 67Ga uptake for predicting disease persistence were compared, and the correlations between those parameters and serum markers were assessed. Results: RI-SUV was significantly higher in patients with increased or unchanged pulmonary lesions at follow-up CT (persistent group; 21.3 ± 9.6%) than in patients with improved pulmonary lesions (improved group; −9.2 ± 28.6%, P = 0.0075). The diagnostic accuracy of RI-SUV in the persistent group was significantly greater than that of early SUV or 67Ga uptake, and serum soluble IL-2 receptor showed a significant correlation with RI-SUV. Conclusions: RI-SUV showed better diagnostic accuracy compared with early SUV or 67Ga uptake, in patients with persistent lung involvement at 1 year. It may be a useful measure of persistent inflammation in patients with pulmonary sarcoidosis.

Introduction 64 Cu-diacetyl-bis ( N 4 -methylthiosemicarbazone) ( 64 Cu-ATSM) is an imaging agent for positron emission tomography (PET) that targets hypoxic tumors. 64 Cu-ATSM is also reported to be a potential agent for internal radiotherapy. In a mouse colon carcinoma (Colon-26) model, we have shown that 64 Cu-ATSM preferentially localizes in intratumoral regions with a high density of CD133 + cells, which show characteristics of cancer stem cells or cancer stem cell-like cells (collectively referred here as CSCs). In this study, we evaluated the therapeutic effect of 64 Cu-ATSM in relation to CD133 expression using this model. Methods Systemic administration of 37 MBq 64 Cu-ATSM or saline was conducted twice within a 1-week interval to mice bearing 1-week-old Colon-26 tumors (days 0–7). At day 19, tumor size measurement, flow cytometry analysis and experimental lung metastatic assay were performed. The therapeutic effect of 64 Cu-ATSM on sorted CD133 + and CD133 − Colon-26 cells was also examined in vitro. Results In vivo studies showed that 64 Cu-ATSM treatment inhibited tumor growth. The percentage of CD133 + cells and metastatic ability in 64 Cu-ATSM treated tumors was decreased compared with that in control animals. In vitro studies demonstrated that 64 Cu-ATSM accumulated in cells under hypoxic conditions and incorporation of 64 Cu-ATSM under hypoxia caused cell death in both CD133 + and CD133 − cells in a similar extent. Conclusions 64 Cu-ATSM administration reduced tumor volume as well as the percentage of CD133 + cells and the metastatic ability of Colon-26 tumors. Together with our data, it is suggested that 64 Cu-ATSM accumulates in regions high in CD133 + highly tumorigenic cells and kills such regions by radiation, resulting in a decrease of the percentage of CD133 + cells.

The aim of the study was to assess the potential usefulness of 3-deoxy-3-18F-fluorothymidine (FLT) as a radiopharmaceutical for imaging the early therapeutic effects of docetaxel (DTX) on tumour proliferation in hormone-refractory prostate cancer (HRPC). Cells of the androgen-independent human prostate tumour cell line, 22Rv1, were implanted in athymic male mice. Approximately 3 weeks after cell implantation, the mice were treated with DTX or vehicle. Before and after the treatment, the mice were imaged with a microPET-Focus-F120 scanner (Concorde Microsystems, Knoxville, TN, USA) using FLT and 18F-fluorodeoxyglucose (FDG). Tracer accumulations in the tumours were then analysed and compared with the proliferation activity and apoptotic index of the tumours. In a separate cell study, 22Rv1 cells were treated with DTX, then incubated with FLT or FDG and examined for their tracer uptake. The microPET imaging showed a significant decrease of FLT uptake in tumours after administration of DTX, while the changes of FDG uptake were minimal. Immunohistochemical analysis of the tumours revealed that the changes of FLT uptake were well correlated with those of proliferation activity but not with the apoptotic index. In vitro studies demonstrated that the significant decrease of FLT uptake in the cells after incubation with DTX correlated with the % S-phase cell fraction, while there were only minimal changes in the prostate-specific antigen concentration of the cell medium and FDG uptake in the cells. These results indicate that FLT is a promising tracer for monitoring the early effects of anticancer therapy with DTX in patients with HRPC.

To investigate the correlation between uptake of 16α-[18F]fluoro-17β-oestradiol (FES) and expression of oestrogen receptors as well as other related immunohistochemistry markers, positron emission tomography (PET) was performed in patients with endometrial carcinoma before surgery. Nineteen patients with endometrioid adenocarcinoma underwent preoperative PET studies with FES and 2-[18F]fluoro-2-deoxy-D-glucose (FDG). Standardized uptake values (SUVs) for each tracer and the regional FDG to FES SUV ratio were calculated using images after coregistration. PET values were compared with postoperative stage, differentiation grade and immunohistochemical scores including oestrogen receptor subtypes (ERα, ERβ), progesterone receptor B (PR-B), Ki-67 and glucose transporter 1 (GLUT1). FES uptake showed a significantly positive correlation with expression of ERα. The FDG to FES ratio showed a significantly negative correlation with expression of ERα and PR-B. The FES uptake and FDG to FES ratio did not correlate with expression of ERβ, Ki-67 or GLUT1. FDG uptake was not correlated with any of the immunohistochemical scores. The PR-B score was strongly correlated with the ERα score. Well-differentiated carcinoma (grade 1) showed a significantly higher FES uptake and significantly lower FDG to FES ratio than moderately or poorly differentiated carcinoma (grade 2–3). None of the PET parameters were significantly different between advanced-stage carcinoma (≥ stage IB) and early-stage carcinoma (IA) based on the Federation International de Gynecologie et d’Obstetrique (FIGO) staging classification. Differentiation grade was the most closely correlated parameter to FES uptake and FDG to FES ratio by multivariate analyses. FES PET combined with FDG would be useful for non-invasive evaluation of ERα distribution, as well as ERα function, which reflects differentiation grade in endometrial carcinoma.

Introduction 64 Cu-diacetyl-bis ( N 4 -methylthiosemicarbazone) ( 64 Cu-ATSM) is a potential imaging agent of hypoxic tumor for use with PET. Recent literature demonstrated that cancer cells expressing CD133, which is a frequently used marker for so-called cancer stem cells or cancer stem cell-like cells (collectively referred to here as CSCs), contribute to tumor's therapeutic resistance and metastasis ability. Culturing under hypoxia is also reported to enlarge the proportion of CD133 + cells, which would indicate survival advantage of CD133 + cells under hypoxia. Here, we investigated the relationships between 64 Cu-ATSM accumulation and existence of CD133 + cells using mouse colon carcinoma (colon-26) tumor. Methods Intratumor distribution of 64 Cu-ATSM and 18 F-fluorodeoxyglucose ( 18 FDG) was compared with immunohistochemical staining for CD133 with a colon-26 model. In vitro characterization of CD133 + colon-26 cells was also performed. Results In colon-26 tumors, 64 Cu-ATSM localized preferentially in regions with a high density of CD133 + cells. The percentage of CD133 + cells was 11-fold higher in 64 Cu-ATSM high-uptake regions compared with 18 FDG high- (but 64 Cu-ATSM low-) uptake regions. CD133 + colon-26 cells showed characteristics previously linked with CSCs in other cancer cell lines, such as high colony-forming ability, high tumor-initiating ability and enrichment under hypoxic cultivation. The proportion of CD133 + cells was enlarged by culturing under glucose starvation as well as hypoxia, and 64 Cu-ATSM uptake was increased under such conditions. Conclusions Our findings showed that, in colon-26 tumors, 64 Cu-ATSM accumulates in rich regions of CD133 + cells with characteristics of CSCs. Therefore 64 Cu-ATSM could be a potential imaging agent for rich regions of CD133 + cells, associated with CSCs, within tumors.