RESUMO
Since the introduction of PET/CT hybrid imaging about two decades ago the landscape of oncological imaging has fundamentally changed, opening a new era of molecular imaging with emphasis on functional characterization of biological processes such as metabolism, cellular proliferation, hypoxia, apoptosis, angiogenesis and immune response. The most commonly assessed functional hallmark of cancer is the increased metabolism in tumor cells due to well-known Warburg effect, because of which FDG has been the most employed radiotracer, the so-called pan-cancer agent, in oncological imaging. However, several limitations such as low specificity and low sensitivity for several histopathological forms of lung cancer as well as high background uptake in the normal tissue of FDG imaging lead to numerous serious pitfalls. This restricts its utilization and diagnostic value in lung cancer imaging, even though this is currently considered to be the method of choice in pulmonary cancer imaging. Accurate initial tumor staging and therapy response monitoring with respect to the TNM criteria plays a crucial role in therapy planning and management in patients with lung cancer. To this end, many efforts have been made for decades to develop novel PET radiopharmaceuticals with innovative approaches that go beyond the assessment of increased glycolytic activity alone. Radiopharmaceuticals targeting DNA synthesis, amino acid metabolism, angiogenesis, or hypoxia have been extensively studied, leading to the emergence of indications for specific clinical questions or as a complementary imaging tool alongside existing conventional or FDG imaging. Nevertheless, despite some initial encouraging results, these tracers couldn't gain a widespread use and acceptance in clinical routine. However, given its mechanism of action and some initial pilot studies regarding lung cancer imaging, FAPI has emerged as a very promising alternative tool that could provide superior or comparable diagnostic performance to FDG imaging in lung cancer entities. Thus, in this review article, we summarized the current PET radiopharmaceuticals, different imaging approaches and discussed the potential benefits and clinical applications of these agents in lung cancer imaging.
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Neoplasias Pulmonares , Compostos Radiofarmacêuticos , Humanos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Neoplasias Pulmonares/diagnóstico por imagem , Neovascularização Patológica , Aminoácidos , Hipóxia , DNARESUMO
Treatment of infected nonunions and severe bone infections is a huge challenge in modern orthopedics. Their treatment routinely includes the use of anti-infective agents. Although frequently used, little is known about their impact on the osteogenesis of mesenchymal stem cells. In a high- and low-dose set-up, this study evaluates the effects of the antibiotics Gentamicin and Vancomycin as well as the antifungal agent Voriconazole on the ability of mesenchymal stem cells to differentiate into osteoblast-like cells and synthesize hydroxyapatite in a monolayer cell culture. The osteogenic activity was assessed by measuring calcium and phosphate concentrations as well as alkaline phosphatase activity and osteocalcin concentration in the cell culture medium supernatant. The amount of hydroxyapatite was measured directly by radioactive 99mTechnetium-HDP labeling. Regarding the osteogenic markers, it could be concluded that the osteogenesis was successful within the groups treated with osteogenic cell culture media. The results revealed that all anti-infective agents have a cytotoxic effect on mesenchymal stem cells, especially in higher concentrations, whereas the measured absolute amount of hydroxyapatite was independent of the anti-infective agent used. Normed to the number of cells it can therefore be concluded that the above-mentioned anti-infective agents actually have a positive effect on osteogenesis while high-dose Gentamycin, in particular, is apparently capable of boosting the deposition of minerals.
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PURPOSE: Since the introduction of PSMA PET/CT with 68Ga-PSMA-11, this modality for imaging prostate cancer (PC) has spread worldwide. Preclinical studies have demonstrated that short-term androgen deprivation therapy (ADT) can significantly increase PSMA expression on PC cells. Additionally, retrospective clinical data in large patient cohorts suggest a positive association between ongoing ADT and a pathological PSMA PET/CT scan. The present evaluation was conducted to further analyse the influence of long-term ADT on PSMA PET/CT findings. METHODS: A retrospective analysis was performed of all 1,704 patients who underwent a 68Ga-PSMA-11 PET/CT scan at our institution from 2011 to 2017 to detect PC. Of 306 patients scanned at least twice, 10 had started and continued ADT with a continuous clinical response between the two PSMA PET/CT scans. These ten patients were included in the current analysis which compared the tracer uptake intensity and volume of PC lesions on PSMA PET/CT before and during ongoing ADT. RESULTS: Overall, 31 PC lesions were visible in all ten patients before initiation of ADT. However, during ongoing ADT (duration 42-369 days, median 230 days), only 14 lesions were visible in eight of the ten patients. The average tracer uptake values decreased in 71% and increased in 12.9% of the PC lesions. Of all lesions, 33.3% were still visible in six patients with a complete PSA response (≤0.1 ng/ml). CONCLUSION: Continuous long-term ADT significantly reduces the visibility of castration-sensitive PC on PSMA PET/CT. If the objective is visualization of the maximum possible extent of disease, we recommend referring patients for PSMA PET/CT before starting ADT.
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Androgênios/metabolismo , Castração , Ácido Edético/análogos & derivados , Oligopeptídeos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/tratamento farmacológico , Idoso , Isótopos de Gálio , Radioisótopos de Gálio , Humanos , Ligantes , Masculino , Pessoa de Meia-Idade , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/cirurgia , Estudos Retrospectivos , Fatores de TempoRESUMO
PURPOSE: The positron emission tomography (PET) tracer 68Ga-PSMA-11, targeting the prostate-specific membrane antigen (PSMA), is rapidly excreted into the urinary tract. This leads to significant radioactivity in the bladder, which may limit the PET-detection of local recurrence (LR) of prostate cancer (PC) after radical prostatectomy (RP), developing in close proximity to the bladder. Here, we analyze if there is additional value of multi-parametric magnetic resonance imaging (mpMRI) compared to the 68Ga-PSMA-11-PET-component of PET/CT or PET/MRI to detect LR. METHODS: One hundred and nineteen patients with biochemical recurrence after prior RP underwent both hybrid 68Ga-PSMA-11-PET/CTlow-dose (1 h p.i.) and -PET/MRI (2-3 h p.i.) including a mpMRI protocol of the prostatic bed. The comparison of both methods was restricted to the abdomen with focus on LR (McNemar). Bladder-LR distance and recurrence size were measured in axial T2w-TSE. A logistic regression was performed to determine the influence of these variables on detectability in 68Ga-PSMA-11-PET. Standardized-uptake-value (SUVmean) quantification of LR was performed. RESULTS: There were 93/119 patients that had at least one pathologic finding. In addition, 18/119 Patients (15.1%) were diagnosed with a LR in mpMRI of PET/MRI but only nine were PET-positive in PET/CT and PET/MRI. This mismatch was statistically significant (p = 0.004). Detection of LR using the PET-component was significantly influenced by proximity to the bladder (p = 0.028). The PET-pattern of LR-uptake was classified into three types (1): separated from bladder; (2): fuses with bladder, and (3): obliterated by bladder). The size of LRs did not affect PET-detectability (p = 0.84), mean size was 1.7 ± 0.69 cm long axis, 1.2 ± 0.46 cm short-axis. SUVmean in nine men was 8.7 ± 3.7 (PET/CT) and 7.0 ± 4.2 (PET/MRI) but could not be quantified in the remaining nine cases (obliterated by bladder). CONCLUSION: The present study demonstrates additional value of hybrid 68Ga-PSMA-11-PET/MRI by gaining complementary diagnostic information compared to the 68Ga-PSMA-11-PET/CTlow-dose for patients with LR of PC.
Assuntos
Imageamento por Ressonância Magnética , Imagem Multimodal/métodos , Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Prostatectomia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia , Idoso , Ácido Edético/análogos & derivados , Reações Falso-Negativas , Isótopos de Gálio , Radioisótopos de Gálio , Humanos , Masculino , Recidiva Local de Neoplasia , Oligopeptídeos , Neoplasias da Próstata/cirurgia , Estudos Retrospectivos , RiscoRESUMO
UNLABELLED: PET imaging with the prostate-specific membrane antigen (PSMA)-targeted radioligand (68)Ga-PSMA-11 is regarded as a significant step forward in the diagnosis of prostate cancer (PCa). More recently, a PSMA ligand was developed that can be labeled with (68)Ga, (111)In, (177)Lu, and (90)Y. This ligand, named PSMA-617, therefore enables both diagnosis and therapy of PCa. The aims of this evaluation were to clinically investigate the distribution of (68)Ga-PSMA-617 in normal tissues and in PCa lesions as well as to evaluate the radiation exposure by the radioligand in PET imaging. METHODS: Nineteen patients, most of them with recurrent PCa, were referred for (68)Ga-PSMA-617 PET/CT. The quantitative assessment of tracer uptake of several organs and of 53 representative tumor lesions was performed in 15 patients at 1 and 3 h after injection. In 4 additional patients, the same procedure was conducted at 5 min, 1 h, 2 h, 3 h, 4 h, and 5 h after injection. On the basis of the data for these 4 patients (mean injected dose, 231 MBq), the radiation exposure of a (68)Ga-PSMA-617 PET/CT was identified. RESULTS: Intense tracer uptake was observed in the kidneys and salivary glands. In 14 of 19 patients (73.7%), at least 1 lesion suspected of being a tumor was detected at 3 h after injection. Of 53 representative tumor lesions selected at 3 h after injection, 47 lesions were visible at 1 h after injection. The mean tumor-to-background ratio for maximum standardized uptake value was 20.4 ± 17.3 (range, 2.3-84.0) at 1 h after injection and 38.2 ± 38.6 (range, 3.6-154.3) at 3 h after injection. The average radiation exposure (effective dose) was approximately 0.021 mSv/MBq. CONCLUSION: Within healthy organs, the kidneys and salivary glands showed the highest (68)Ga-PSMA-617 uptake. The radiation exposure was relatively low. (68)Ga-PSMA-617 shows PCa lesions with high contrast. Images obtained between 2 and 3 h after injection seem to be the best option with regard to radiotracer uptake and tumor contrast. Later images can help to clarify unclear lesions.
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Dipeptídeos/uso terapêutico , Radioisótopos de Gálio/uso terapêutico , Compostos Heterocíclicos com 1 Anel/uso terapêutico , Compostos Organometálicos/uso terapêutico , Antígeno Prostático Específico/química , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Compostos Radiofarmacêuticos/uso terapêutico , Nanomedicina Teranóstica , Adulto , Ácido Edético/análogos & derivados , Isótopos de Gálio , Humanos , Processamento de Imagem Assistida por Computador , Rim/diagnóstico por imagem , Rim/metabolismo , Masculino , Pessoa de Meia-Idade , Oligopeptídeos , Tomografia por Emissão de Pósitrons , Neoplasias da Próstata/metabolismo , Radiometria , Glândulas Salivares/diagnóstico por imagem , Glândulas Salivares/metabolismo , Distribuição TecidualRESUMO
UNLABELLED: The performance of cytotoxic drugs is defined by their selectivity of uptake and action in tumor tissue. Recent clinical responses achieved by treating metastatic malignant melanoma with therapeutic modalities based on gene expression profiling showed that malignant melanoma is amenable to systemic treatment. However, these responses are not persistent, and complementary targeted treatment strategies are required for malignant melanoma. METHODS: Here we provide our experience with different labeling procedures for the radioiodination of benzamides and report on initial dosimetry data and the first therapeutic application of (131)I-BA52, a novel melanin-binding benzamide in patients with metastatic malignant melanoma. Twenty-six adults with histologically documented metastasized malignant melanoma received a single dose of 235 ± 62 MBq of (123)I-BA52 for planar and SPECT/CT imaging. Nine patients were selected for radionuclide therapy and received a median of 4 GBq (minimum, 0.51 GBq; maximum, 6.60 GBq) of the ß-emitting radiopharmaceutical (131)I-BA52. RESULTS: A trimethyltin precursor-based synthesis demonstrated high radiochemical yields in the large-scale production of radioiodinated benzamides required for clinical application. (123)I-BA52 showed specific uptake and long-term retention in tumor tissue with low transient uptake in the excretory organs. In tumor tissue, a maximum dose of 12.2 Gy per GBq of (131)I-BA52 was calculated. The highest estimated dose to a normal organ was found for the lung (mean, 3.1 Gy/GBq). No relevant acute or mid-term toxicity was observed with the doses administered until now. Even though dosimetric calculations reveal that the doses applied in this early phase of clinical application can be significantly increased, we observed antitumor effects with follow-up imaging, and single patients of the benzamide-positive cohort of patients (3/5 of the patients receiving a dose > 4.3 GBq) demonstrated a surprisingly long survival of more than 2 y. CONCLUSION: These data indicate that systemic radionuclide therapy using (131)I-BA52 as a novel approach for the therapy of malignant melanoma is of considerable potential. Future trials should be done to enhance the precision of dosimetry, validate the maximum tolerable dose, and evaluate the effectiveness of the treatment in a prospective manner.
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Benzamidas/química , Benzamidas/uso terapêutico , Benzodioxóis/uso terapêutico , Radioisótopos do Iodo/uso terapêutico , Melaninas/química , Melanoma/radioterapia , Compostos Radiofarmacêuticos/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Mutação , Metástase Neoplásica , Fenótipo , Radiometria , Radioterapia/tendências , Tomografia Computadorizada de Emissão de Fóton Único , Tomografia Computadorizada por Raios XRESUMO
Radiolabeling is a valuable option for tracking drug molecules in biodistribution experiments. In the development of innovative drug delivery systems the influence of the pharmaceutical formulation on the drugs' pharmacokinetics has to be investigated. The hypolipidemic agent fenofibrate is an ideal model drug for testing the performance of drug delivery systems designed for poorly soluble compounds. Herein, we report a de novo synthesis of a fenofibrate derivative, dechloro-4-iodofenofibrate, as well as its conversion into its radioiodinated derivatives containing (125)I or (131)I. The enzymatic stability of the radiolabeled compounds synthesized was determined in vitro. A scintigraphic imaging study supplemented by biodistribution experiments and analysis of excreted metabolites revealed the stability required for in vivo applications and its similarity to fenofibrate. Therefore a convenient method is presented to synthesize radioiodinated derivatives of fenofibrate. These tracers show excellent in vitro and in vivo properties to study the behavior of lipophilic drugs.
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Fenofibrato/análogos & derivados , Fenofibrato/farmacocinética , Hipolipemiantes/farmacocinética , Imagem Molecular/métodos , Animais , Feminino , Humanos , Interações Hidrofóbicas e Hidrofílicas , Radioisótopos do Iodo , Fígado/metabolismo , Camundongos , Traçadores Radioativos , Soro/metabolismo , Solubilidade , Distribuição TecidualRESUMO
BACKGROUND: Treatment options in patients with amyloidotic transthyretin (ATTR) cardiomyopathy are limited. Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea (GT), inhibits fibril formation from several amyloidogenic proteins in vitro. Thus, it might also halt progression of TTR amyloidosis. This is a single-center observational report on the effects of GT consumption in patients with ATTR cardiomopathy. METHODS: 19 patients with ATTR cardiomyopathy were evaluated by standard blood tests, echocardiography, and cardiac MRI (n = 9) before and after consumption of GT and/or green tea extracts (GTE) for 12 months. RESULTS: Five patients were not followed up for reasons of death (n = 2), discontinuation of GT/GTE consumption (n = 2), and heart transplantation (n = 1). After 12 months no increase of left ventricular (LV) wall thickness and LV myocardial mass was observed by echocardiography. In the subgroup of patients evaluated by cardiac MRI a mean decrease of LV myocardial mass (-12.5 %) was detected in all patients. This was accompanied by an increase of mean mitral annular systolic velocity of 9 % in all 14 patients. Total cholesterol (191.9 ± 8.9 vs. 172.7 ± 9.4 mg/dL; p < 0.01) and LDL cholesterol (105.8 ± 7.6 vs. 89.5 ± 8.0 mg/dL; p < 0.01) decreased significantly during the observational period. No serious adverse effects were reported by any of the participants. CONCLUSIONS: Our observation suggests an inhibitory effect of GT and/or GTE on the progression of cardiac amyloidosis. We propose a randomized placebo-controlled investigation to confirm our observation.
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Neuropatias Amiloides Familiares/tratamento farmacológico , Cardiomiopatias/tratamento farmacológico , Catequina/análogos & derivados , Chá/química , Idoso , Neuropatias Amiloides Familiares/fisiopatologia , Cardiomiopatias/fisiopatologia , Catequina/isolamento & purificação , Catequina/farmacologia , Colesterol/sangue , Estudos de Coortes , Progressão da Doença , Feminino , Seguimentos , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/metabolismo , Extratos Vegetais/farmacologiaRESUMO
UNLABELLED: We investigated the feasibility of radioiodine therapy targeting hepatoma cells (MH3924A) by tissue-specific expression of the human sodium/iodide symporter (hNIS) gene directed by the murine albumin enhancer and promoter (mAlb). METHODS: The cell-specific transcriptional activity of mAlb was examined by a luciferase assay in several transiently transfected cell lines. MH3924A cells were stably transfected with the recombinant retroviral vector, in which hNIS complementary DNA expression was driven by mAlb and coupled to hygromycin resistance gene using an internal ribosomal entry site (IRES). Functional hNIS expression in hepatoma cells was confirmed by an iodide uptake assay. In imaging studies, the tumor-bearing ACI rats were intravenously injected with (131)I and imaged with a gamma-camera. Biodistribution was studied at 30 min and at 1, 3, 6, and 25 h after injection of (131)I. Toxic effects of (131)I on hepatoma cells were studied in vitro and in vivo. RESULTS: Stably transfected MH3924A cells concentrated (125)I up to 240-fold higher than the wild-type cells. The iodide uptake in stably transfected cells was inhibited by ouabain and sodium perchlorate but increased by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. An in vitro clonogenic assay revealed an 86% decrease in colony number in stably transfected cells after exposure to 3.7 MBq/mL of (131)I and only about 8% in hNIS-negative control cells. Furthermore, the in vivo study showed intense tracer accumulation in hNIS-expressing tumors after administration of (131)I. At 3 h after intraperitoneal injection, the transfected tumors accumulated (131)I 19.2-fold higher than the parental tumors in a biodistribution study. Moreover, administration of a therapeutic dose of (131)I resulted in an inhibition of hNIS-expressing tumor growth, whereas control tumors continued to increase in size. CONCLUSION: A therapeutic effect of (131)I on hepatoma cells in vitro and in vivo has been demonstrated after tumor-specific iodide uptake induced by mAlb-directed hNIS gene expression. Because a stable transformed cell line has been used in these experiments, the clinical potential of this strategy must be evaluated after in vivo transfection of hepatoma cells.
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Carcinoma Hepatocelular/radioterapia , Radioisótopos do Iodo/uso terapêutico , Neoplasias Hepáticas/radioterapia , Simportadores/genética , Albuminas/genética , Animais , Antineoplásicos/farmacologia , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Transformada , Modelos Animais de Doenças , Técnicas de Transferência de Genes , Humanos , Regiões Promotoras Genéticas , Ratos , Fatores de Tempo , Distribuição TecidualRESUMO
PURPOSE: Selective delivery of drugs into the target tissue is expected to result in high drug concentrations in the tissue of interest and therefore enhanced drug efficacy. To develop a peptide-based radiopharmaceutical, we investigated the properties of a peptide with affinity for human breast cancer, which has been selected through phage display. EXPERIMENTAL DESIGN: The bioactivity of the p160 peptide (VPWMEPAYQRFL) was evaluated in vitro and in vivo. The specific binding to human breast cancer MDA-MB-435 cells was confirmed in competition experiments. Internalization of the peptide was investigated with confocal microscopy. Furthermore, the biodistribution of (131)I-labeled p160 was studied in tumor-bearing mice. In vivo stability was evaluated at different periods after tracer administration using high-performance liquid chromatography analysis. RESULTS: The binding of (125)I-labeled p160 was inhibited up to 95% by the unlabeled peptide with an IC(50) value of 0.6 micromol/L. In addition, 40% of the total bound activity was found to be internalized into the human breast cancer cells. Although a rapid degradation was seen, biodistribution studies in nude mice showed a higher uptake in tumor than in most of the organs. Perfusion of the animals caused a reduction of the radioligand accumulation in the healthy tissues, whereas the tumor uptake remained constant. A comparison of [(131)I]p160 with a (131)I-labeled Arg-Gly-Asp peptide revealed a higher tumor-to-organ ratio for [(131)I]p160. CONCLUSIONS: p160 has properties that make it an attractive carrier for tumor imaging and the intracellular delivery of isotopes or chemotherapeutic drugs.
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Neoplasias da Mama/metabolismo , Oligopeptídeos/metabolismo , Sequência de Aminoácidos , Animais , Ligação Competitiva , Neoplasias da Mama/patologia , Linhagem Celular , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos/métodos , Células Endoteliais/metabolismo , Humanos , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microscopia Confocal , Transplante de Neoplasias , Octreotida/metabolismo , Octreotida/farmacocinética , Oligopeptídeos/farmacocinética , Ensaio Radioligante , Fatores de Tempo , Distribuição Tecidual , Transplante HeterólogoRESUMO
Investigations into tumor angiogenesis and antiangiogenic treatment have renewed interest in tumor perfusion. To image tumor blood-pool by PET, suitable tracers are not generally available. In this experimental study, we characterized a 68Ga-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugate of rat serum albumin (68Ga-DOTA-RSA) in vivo using a generator-produced isotope. Biodistribution was determined in ACI rats after intravenous administration of 3-6 MBq of 68Ga-DOTA-RSA. Three ACI rats were imaged over 1 h by dynamic PET after intravenous administration of 15-25 MBq of 68Ga-DOTA-RSA while the blood-pool activity was recorded simultaneously in a closed extracorporeal loop (ECL) between the carotid artery and the jugular vein. Time-activity curves (TACs) were obtained from volume of interest (VOI) analysis and from the ECL data. Stability and metabolites in plasma and urine were analyzed by size exclusion HPLC (SE-HPLC) 1 h after intravenous injection of 67Ga-DOTA-RSA. Blood radioactivity decreased by 10% and 18% from 10 to 60 min p.i. by biodistribution and PET or ECL, respectively. Tissue sampling between 10 and 60 min p.i. showed slight increases in the uptake of spleen, myocardium, kidney and skeletal muscle while hepatic accretion remained unchanged. Total urinary excretion after 60 min amounted to 9% of the injected dose. HPLC demonstrated a single urinary metabolite corresponding in size to gallium-labeled DOTA. 68Ga-DOTA-RSA is a blood-pool tracer whose physical and biological half-life is well suited for PET. Our findings support clinical imaging using 68Ga-DOTA-labeled human serum albumin (HSA). The generator-produced label makes 68Ga-DOTA-labeled albumin continuously available even to centers lacking an in-house cyclotron.