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Because of the blood-brain barrier (BBB), successful drug delivery to the brain has long been a key objective for the medical community, calling for pioneering technologies to overcome this challenge. Convection-enhanced delivery (CED), a form of direct intraparenchymal microinfusion, shows promise but requires optimal infusate design and real-time distribution monitoring. The size of the infused substances appears to be especially critical, with current knowledge being limited. Herein, we examined the intracranial administration of polyethylene glycol (PEG)-coated nanoparticles (NPs) of various sizes using CED in groups of healthy minipigs (n = 3). We employed stealth liposomes (LIPs, 130 nm) and two gold nanoparticle designs (AuNPs) of different diameters (8 and 40 nm). All were labeled with copper-64 for quantitative and real-time monitoring of the infusion via positron emission tomography (PET). NPs were infused via two catheters inserted bilaterally in the putaminal regions of the animals. Our results suggest CED with NPs holds promise for precise brain drug delivery, with larger LIPs exhibiting superior distribution volumes and intracranial retention over smaller AuNPs. PET imaging alongside CED enabled dynamic visualization of the process, target coverage, timely detection of suboptimal infusion, and quantification of distribution volumes and concentration gradients. These findings may augment the therapeutic efficacy of the delivery procedure while mitigating unwarranted side effects associated with nonvisually monitored delivery approaches. This is of vital importance, especially for chronic intermittent infusions through implanted catheters, as this information enables informed decisions for modulating targeted infusion volumes on a catheter-by-catheter, patient-by-patient basis.
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Encéfalo , Ouro , Nanopartículas Metálicas , Tamanho da Partícula , Polietilenoglicóis , Porco Miniatura , Animais , Suínos , Ouro/química , Nanopartículas Metálicas/química , Polietilenoglicóis/química , Encéfalo/metabolismo , Encéfalo/diagnóstico por imagem , Sistemas de Liberação de Medicamentos , Tomografia por Emissão de Pósitrons , Lipossomos/química , Convecção , Barreira Hematoencefálica/metabolismo , Radioisótopos de Cobre/química , Nanopartículas/químicaRESUMO
Effective therapeutics are necessary for managing severe COVID-19 disease despite the availability of vaccines. Small interfering RNA (siRNA) can silence viral genes and restrict SARS-CoV-2 replication. Cell-penetrating peptides is a robust method for siRNA delivery, enhancing siRNA stability and targeting specific receptors. We developed a peptide HE25 that blocks SARS-CoV-2 replication by various mechanisms, including the binding of multiple receptors involved in the virus's internalization, such as ACE2, integrins and NRP1. HE25 not only acts as a vehicle to deliver the SARS-CoV-2 RNA-dependent RNA polymerase siRNA into cells but also facilitates their internalization through endocytosis. Once inside endosomes, the siRNA is released into the cytoplasm through the Histidine-proton sponge effect and the selective cleavage of HE25 by cathepsin B. These mechanisms effectively inhibited the replication of the ancestral SARS-CoV-2 and the Omicron variant BA.5 in vitro. When HE25 was administered in vivo, either by intravenous injection or inhalation, it accumulated in lungs, veins and arteries, endothelium, or bronchial structure depending on the route. Furthermore, the siRNA/HE25 complex caused gene silencing in lung cells in vitro. The SARS-CoV-2 siRNA/HE25 complex is a promising therapeutic for COVID-19, and a similar strategy can be employed to combat future emerging viral diseases.
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The gastrin-releasing peptide receptor (GRPR) is known to be overexpressed in breast cancer, making it a promising target for both imaging and therapy within a theranostic framework. Various radioligands targeting GRPR have undergone investigation in preclinical and clinical studies related to breast cancer. This systematic scoping review aimed to assess the current evidence on GRPR-targeted radioligands for diagnostic and therapeutic applications in breast cancer. The methodology followed the PRISMA-ScR protocol. The literature search was conducted in September 2023 and encompassed MEDLINE, Embase, Cochrane, and Scopus databases. We included original peer-reviewed studies focused on breast cancer patients or in vivo breast cancer models. Two reviewers performed the study selection process independently. Data were extracted, synthesized, and categorized into preclinical and clinical studies, further subdivided based on radioligand properties. A total of 35 original studies were included in the review, with three of them evaluating therapeutic outcomes. The results indicated that GRPR-radioantagonists are superior to GRPR-agonists, exhibiting preferable in vivo stability, rapid, specific tumor targeting, and enhanced retention. Both preclinical and clinical evaluations demonstrated renal excretion and high uptake in normal GRPR-expressing tissue, primarily the pancreas. A significant positive correlation was observed between GRPR and estrogen-receptor expression. In the clinical setting, GRPR-radioligands effectively detected primary tumors and, to a lesser extent, lymph node metastases. Moreover, GRPR-targeted radioantagonists successfully identified distant metastases originating from various sites in advanced metastatic disease, strongly correlated with positive estrogen receptor expression. Preclinical therapeutic evaluation of GRPR-radioligands labeled with lutetium-177 showed promising tumor responses, and none of the studies reported any observed or measured side effects, indicating a safe profile. In conclusion, the evidence presented in this review indicates a preference for GRPR-targeted antagonists over agonists, owing to their superior kinetics and promising diagnostic potential. Clinical assessments suggested diagnostic value for GRPR-targeted theranostics in breast cancer patients, particularly those with high estrogen receptor expression. Nevertheless, in the therapeutic clinical context, paying attention to the radiation dose administered to the pancreas and kidneys is crucial.
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Neoplasias da Mama , Receptores da Bombesina , Humanos , Feminino , Receptores da Bombesina/metabolismo , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/terapia , Neoplasias da Mama/patologia , Medicina de Precisão , Receptores de EstrogênioRESUMO
Prostate-specific membrane antigen (PSMA), highly expressed in prostate cancer, is a promising target for radionuclide therapy. Auger electron-emitting radionuclides are well suited for targeted radionuclide therapy if they can be delivered close to the DNA of the targeted cells. This preclinical study evaluated the theranostic pair [55/58mCo]Co-DOTA-PSMA-617 for PET imaging and Auger electron therapy of prostate cancer. [58mCo]Co-DOTA-PSMA-617 was successfully prepared with > 99% radiochemical yield and purity. In vitro, uptake and subcellular distribution assays in PSMA-positive prostate cancer cells showed PSMA-specific uptake with high cell-associated activity in the nucleus. Incubation with [58mCo]Co-DOTA-PSMA-617 reduced cell viability and clonogenic survival in a significant dose-dependent manner (p < 0.05). Biodistribution of xenografted mice showed high specific tumor uptake of the cobalt-labeled PSMA ligand for all time points with rapid clearance from normal tissues, which PET imaging confirmed. In vivo, therapy with [58mCo]Co-DOTA-PSMA-617 in tumor-bearing mice demonstrated significantly increased median survival for treated mice compared to control animals (p = 0.0014). In conclusion, [55/58mCo]Co-DOTA-PSMA-617 displayed excellent in vitro and in vivo properties, offering significant survival benefits in mice with no observed toxicities.
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Elétrons , Neoplasias da Próstata , Masculino , Humanos , Camundongos , Animais , Distribuição Tecidual , Linhagem Celular Tumoral , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Neoplasias da Próstata/patologia , Glutamato Carboxipeptidase II/metabolismo , Antígenos de Superfície/metabolismo , Radioisótopos , Compostos Radiofarmacêuticos/uso terapêutico , Compostos Radiofarmacêuticos/químicaRESUMO
BACKGROUND: The somatostatin receptors 1-5 are overexpressed on neuroendocrine neoplasms and, as such, represent a favorable target for molecular imaging. This study investigates the potential of [18F]AlF-NOTA-[1-Nal3]-Octreotide and compares it in vivo to DOTA- and NOTA-[1-Nal3]-Octreotide radiolabeled with gallium-68. METHODS: DOTA- and NOTA-NOC were radiolabeled with gallium-68 and NOTA-NOC with [18F]AlF. Biodistributions of the three radioligands were evaluated in AR42J xenografted mice at 1 h p.i and for [18F]AlF at 3 h p.i. Preclinical PET/CT was applied to confirm the general uptake pattern. RESULTS: Gallium-68 was incorporated into DOTA- and NOTA-NOC in yields and radiochemical purities greater than 96.5%. NOTA-NOC was radiolabeled with [18F]AlF in yields of 38 ± 8% and radiochemical purity above 99% after purification. The biodistribution in tumor-bearing mice showed a high uptake in tumors of 26.4 ± 10.8 %ID/g for [68Ga]Ga-DOTA-NOC and 25.7 ± 5.8 %ID/g for [68Ga]Ga-NOTA-NOC. Additionally, [18F]AlF-NOTA-NOC exhibited a tumor uptake of 37.3 ± 10.5 %ID/g for [18F]AlF-NOTA-NOC, which further increased to 42.1 ± 5.3 %ID/g at 3 h p.i. CONCLUSIONS: The high tumor uptake of all radioligands was observed. However, [18F]AlF-NOTA-NOC surpassed the other clinically well-established radiotracers in vivo, especially at 3 h p.i. The tumor-to-blood and -liver ratios increased significantly over three hours for [18F]AlF-NOTA-NOC, making it possible to detect liver metastases. Therefore, [18F]AlF demonstrates promise as a surrogate pseudo-radiometal to gallium-68.
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Radioisótopos de Gálio , Tumores Neuroendócrinos , Animais , Camundongos , Tumores Neuroendócrinos/diagnóstico por imagem , Receptores de Somatostatina/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Octreotida , Distribuição Tecidual , Tomografia por Emissão de Pósitrons/métodos , Compostos RadiofarmacêuticosRESUMO
The antimony(iii) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) has been prepared and its exceptionally low stability observed. The Sb(iii) ion in Na[Sb(DOTA)]·4H2O shows an approximately square antiprismatic coordination geometry that is close to superimposable to the Bi(iii) geometry in [Bi(DOTA)]- in two phases containing this anion, Na[Bi(DOTA)]·4H2O, [H3O][Bi(DOTA)]·H2O for which structures are also described. Interestingly, DOTA itself in [(H6DOTA)]Cl2·4H2O·DMSO shows the same orientation of the N4O4 metal binding cavity reflecting the limited flexibility of DOTA in an octadentate coordination mode. In 8-coordinate complexes it can however accommodate M(iii) ions with r ion spanning a relatively wide range from 87 pm (Sc(iii)) to 117 pm (Bi(iii)). The larger Bi3+ ion appears to be the best metal-ligand size match since [Bi(DOTA)]- is associated with greater complex stability. In the solution state, [Sb(DOTA)]- is extremely susceptible to transmetallation by trivalent ions (Sc(iii), Y(iii), Bi(iii)) and, significantly, even by biologically important divalent metal ions (Mg(ii), Ca(ii), Zn(ii)). In all cases just one equivalent is enough to displace most of the Sb(iii). [Sb(DOTA)]- is resistant to hydrolysis; however, since biologically more abundant metal ions easily substitute the antimony, DOTA complexes will not be suitable for deployment for the delivery of the, so far unexploited, theranostic isotope pair 119Sb and 117Sb.
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BACKGROUND: Glioblastomas are highly resistant to therapy, and virtually all patients experience tumor recurrence after standard-of-care treatment. Surgical tumor resection is a cornerstone in glioblastoma therapy, but its impact on cellular phenotypes in the local postsurgical microenvironment has yet to be fully elucidated. METHODS: We developed a preclinical orthotopic xenograft tumor resection model in rats with integrated 18F-FET PET/CT imaging. Primary and recurrent tumors were subject to bulk and single-cell RNA sequencing. Differentially expressed genes and pathways were investigated and validated using tissue specimens from the xenograft model, 23 patients with matched primary/recurrent tumors, and a cohort including 190 glioblastoma patients. Functional investigations were performed in vitro with multiple patient-derived cell cultures. RESULTS: Tumor resection induced microglia/macrophage infiltration, angiogenesis as well as proliferation and upregulation of several stem cell-related genes in recurrent tumor cells. Expression changes of selected genes SOX2, POU3F2, OLIG2, and NOTCH1 were validated at the protein level in xenografts and early recurrent patient tumors. Single-cell transcriptomics revealed the presence of distinct phenotypic cell clusters in recurrent tumors which deviated from clusters found in primary tumors. Recurrent tumors expressed elevated levels of pleiotrophin (PTN), secreted by both tumor cells and tumor-associated microglia/macrophages. Mechanistically, PTN could induce tumor cell proliferation, self-renewal, and the stem cell program. In glioblastoma patients, high PTN expression was associated with poor overall survival and identified as an independent prognostic factor. CONCLUSION: Surgical tumor resection is an iatrogenic driver of PTN-mediated self-renewal in glioblastoma tumor cells that promotes therapeutic resistance and tumor recurrence.
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Neoplasias Encefálicas , Glioblastoma , Animais , Neoplasias Encefálicas/tratamento farmacológico , Proteínas de Transporte , Citocinas , Glioblastoma/genética , Humanos , Recidiva Local de Neoplasia/patologia , Células-Tronco Neoplásicas/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Ratos , Células-Tronco , Microambiente TumoralRESUMO
INTRODUCTION: Treatment of glioblastomas (GBM) using the Auger electron emitting compound [125I]5-Iodo-2'-deoxyuridine ([125I]I-UdR), combined with the thymidylate synthase inhibitor methotrexate (MTX) and concomitant chemotherapy with temozolomide (TMZ) has recently shown very promising therapeutic effects in vitro and in vivo in animals. The aim of the current study was to investigate if the therapeutic effects of this multimodal treatment strategy could be further increased by the thymidylate synthase inhibitor, 5-fluoro-2'-deoxyuridine (F-UdR), in comparison to MTX, and if the co-treatment should be given in a neoadjuvant or adjuvant setting. METHODS: A patient-derived GBM cancer stem cell (CSC)-enriched cell line, grown as neurospheres, was employed to evaluate DNA-incorporation of [125I]I-UdR, determined by a DNA precipitation assay, using either pre-treatment or co-treatment with MTX or F-UdR. The therapeutic effects in the CSC-enriched cell line after exposure to various combinations of MTX, F-UdR, TMZ and [125I]I-UdR were also investigated by a CellTiter-Blue assay. RESULTS: The highest general increase in [125I]I-UdR incorporation was observed with F-UdR co-treatment, which resulted in approx. 2.5-fold increase in the DNA-associated activity. Also the cell viability was significantly decreased when F-UdR was combined with [125I]I-UdR compared to [125I]I-UdR alone at all activity concentrations tested. MTX was redundant when combined with 400 and 500 Bq/ml [125I]I-UdR. TMZ was effective in combination with either [125I]I-UdR alone or with both thymidylate synthase inhibitors combined with 50-100 Bq/ml [125I]I-UdR. CONCLUSIONS: Overall, our study revealed a higher incorporation and therapeutic effect of [125I]I-UdR when GBM cells were co-treated with F-UdR compared to MTX. The therapeutic effects were further increased when TMZ was combined with [125I]I-UdR in combination with the thymidylate synthase inhibitors. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: Auger electron therapy in combination with thymidylate synthase inhibition and concomitant chemotherapy has the potential to become a future therapeutic treatment option for patients with glioblastoma.
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Glioblastoma , Radioisótopos do Iodo , Neoplasias Encefálicas , Sobrevivência Celular , Humanos , Células-Tronco Neoplásicas , Células Tumorais CultivadasRESUMO
BACKGROUND: With increasing clinical demand for gallium-68, commercial germanium-68/gallium-68 ([68Ge]Ge/[68Ga]Ga) generators are incapable of supplying sufficient amounts of the short-lived daughter isotope. In this study, we demonstrate a high-yield, automated method for producing multi-Curie levels of [68Ga]GaCl3 from solid zinc-68 targets and subsequent labelling to produce clinical-grade [68Ga]Ga-PSMA-11 and [68Ga]Ga-DOTATATE. RESULTS: Enriched zinc-68 targets were irradiated at up to 80 µA with 13 MeV protons for 120 min; repeatedly producing up to 194 GBq (5.24 Ci) of purified gallium-68 in the form of [68Ga]GaCl3 at the end of purification (EOP) from an expected > 370 GBq (> 10 Ci) at end of bombardment. A fully automated dissolution/separation process was completed in 35 min. Isolated product was analysed according to the Ph. Eur. monograph for accelerator produced [68Ga]GaCl3 and found to comply with all specifications. In every instance, the radiochemical purity exceeded 99.9% and importantly, the radionuclidic purity was sufficient to allow for a shelf-life of up to 7 h based on this metric alone. Fully automated production of up to 72.2 GBq [68Ga]Ga-PSMA-11 was performed, providing a product with high radiochemical purity (> 98.2%) and very high apparent molar activities of up to 722 MBq/nmol. Further, manual radiolabelling of up to 3.2 GBq DOTATATE was performed in high yields (> 95%) and with apparent molar activities (9-25 MBq/nmol) sufficient for clinical use. CONCLUSIONS: We have developed a high-yielding, automated method for the production of very high amounts of [68Ga]GaCl3, sufficient to supply proximal radiopharmacies. The reported method led to record-high purified gallium-68 activities (194 GBq at end of purification) and subsequent labelling of PSMA-11 and DOTATATE. The process was highly automated from irradiation through to formulation of the product, and as such comprised a high level of radiation protection. The quality control results obtained for both [68Ga]GaCl3 for radiolabelling and [68Ga]Ga-PSMA-11 are promising for clinical use.
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Gastrin-releasing peptide receptor (GRPR) is overexpressed in the majority of prostate cancers. This study aimed to investigate the potential of 64Cu (radionuclide for late time-point PET-imaging) for imaging of GRPR expression using NOTA-PEG2-RM26 and NODAGA-PEG2-RM26. Methods: NOTA/NODAGA-PEG2-RM26 were labeled with 64Cu and evaluated in GRPR-expressing PC-3 cells. Biodistribution of [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was studied in PC-3 xenografted mice and compared to the biodistribution of [57Co]Co-NOTA/NODAGA-PEG2-RM26 at 3 and 24 h p.i. Preclinical PET/CT imaging was performed in tumor-bearing mice. NOTA/NODAGA-PEG2-RM26 were stably labeled with 64Cu with quantitative yields. In vitro, binding of [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was rapid and GRPR-specific with slow internalization. In vivo, [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 bound specifically to GRPR-expressing tumors with fast clearance from blood and normal organs and displayed generally comparable biodistribution profiles to [57Co]Co-NOTA/NODAGA-PEG2-RM26; tumor uptake exceeded normal tissue uptake 3 h p.i.. Tumor-to-organ ratios did not increase significantly with time. [64Cu]Cu-NOTA-PEG2-RM26 had a significantly higher liver and pancreas uptake compared to other agents. 57Co-labeled radioconjugates showed overall higher tumor-to-non-tumor ratios, compared to the 64Cu-labeled counterparts. [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was able to visualize GRPR-expression in a murine PC model using PET. However, [55/57Co]Co-NOTA/NODAGA-PEG2-RM26 provided better in vivo stability and overall higher tumor-to-non-tumor ratios compared with the 64Cu-labeled conjugates.
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Antineoplásicos/farmacologia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/tratamento farmacológico , Receptores da Bombesina/antagonistas & inibidores , Animais , Antineoplásicos/química , Radioisótopos de Cobalto , Radioisótopos de Cobre , Humanos , Masculino , Camundongos , Neoplasias Experimentais/diagnóstico por imagem , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Células PC-3 , Neoplasias da Próstata/metabolismo , Receptores da Bombesina/genética , Receptores da Bombesina/metabolismoRESUMO
Despite promising anti-cancer properties in vitro, all titanium-based pharmaceuticals have failed in vivo. Likewise, no target-specific positron emission tomography (PET) tracer based on the radionuclide 45Ti has been developed, notwithstanding its excellent PET imaging properties. In this contribution, we present liquid-liquid extraction (LLE) in flow-based recovery and the purification of 45Ti, computer-aided design, and the synthesis of a salan-natTi/45Ti-chelidamic acid (CA)-prostate-specific membrane antigen (PSMA) ligand containing the Glu-urea-Lys pharmacophore. The compound showed compromised serum stability, however, no visible PET signal from the PC3+ tumor was seen, while the ex vivo biodistribution measured the tumor accumulation at 1.1% ID/g. The in vivo instability was rationalized in terms of competitive citrate binding followed by Fe(III) transchelation. The strategy to improve the in vivo stability by implementing a unimolecular ligand design is presented.
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Simulação por Computador , Neoplasias Experimentais/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Neoplasias da Próstata/diagnóstico por imagem , Compostos Radiofarmacêuticos , Titânio , Animais , Ácido Glutâmico/química , Ácido Glutâmico/farmacologia , Humanos , Calicreínas/química , Calicreínas/farmacocinética , Calicreínas/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/metabolismo , Células PC-3 , Antígeno Prostático Específico/química , Antígeno Prostático Específico/farmacocinética , Antígeno Prostático Específico/farmacologia , Neoplasias da Próstata/metabolismo , Piridonas/química , Piridonas/farmacocinética , Piridonas/farmacologia , Traçadores Radioativos , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/farmacologia , Titânio/química , Titânio/farmacocinética , Titânio/farmacologia , Ureia/química , Ureia/farmacologiaRESUMO
PET imaging at late time points after injection may allow tracer clearance from normal tissue and hence improve image contrast and detectability. 55Co is a promising isotope with high positron yield and a long half-life suitable for imaging at delayed time points. Here, we compared the 3 radioconjugates [68Ga]Ga-DOTATATE, [64Cu]Cu-DOTATATE, and [55Co]Co-DOTATATE by PET/CT imaging in NOD-SCID mice bearing subcutaneous somatostatin receptor-expressing AR42J tumors. Methods:55Co and 64Cu were produced by the 54Fe(d,n)55Co and 64Ni(p,n)64Cu nuclear reactions, whereas 68Ga was obtained from a 68Ge/68Ga generator. 55Co and 64Cu were labeled with DOTATATE by heating in a sodium acetate buffer and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer, respectively. AR42J tumor-bearing mice were dynamically scanned 0-1 h after injection. For 64Cu and 55Co, additional imaging was also performed at late time points after 4 and 24 h. Dose calculations were based on a known biodistribution. The cumulated disintegrations in each organ were calculated by integration of a fitted exponential function to the biodistribution of each respective organ. Equivalent doses were calculated by OLINDA/EXM using the MIRD formalism. Results: Tumor uptake was rapid from 0 to 1 h after injection for all 3 radioconjugates. Normal-tissue ratios as represented by tumor-to-liver, tumor-to-kidney, and tumor-to-muscle ratios increased significantly over time, with [55Co]Co-DOTATATE reaching the highest ratio of all radioconjugates. For [55Co]Co-DOTATATE, the tumor-to-liver ratio increased to 65 ± 16 at 4 h and 50 ± 6 at 24 h, which were 15 (P < 0.001) and 30 (P < 0.001) times higher, respectively, than the corresponding ratios for [64Cu]Cu-DOTATATE and 5 (P < 0.001) times higher than that of [68Ga]Ga-DOTATATE at 1 h. Correspondingly, tumor-to-kidney and tumor-to-muscle ratios for [55Co]Co-DOTATATE were 4 (P < 0.001) and 11 (P < 0.001) times higher than that of [64Cu]Cu-DOTATATE at 24 h. An equivalent dose was calculated as 9.6E-02 mSv/MBq for [55Co]Co-DOTATATE. Conclusion: [55Co]Co-DOTATATE demonstrated superior image contrast compared with [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE for PET imaging of somatostatin receptor-expressing tumors, warranting translation into clinical trials. Dosimetry calculations found that effective doses for [55Co]Co-DOTATATE were comparable to those for both [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE.
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Radioisótopos de Cobalto , Octreotida/análogos & derivados , Compostos Organometálicos , Tomografia por Emissão de Pósitrons/métodos , Razão Sinal-Ruído , Adulto , Animais , Linhagem Celular Tumoral , Transformação Celular Neoplásica , Humanos , Masculino , Camundongos , Octreotida/farmacocinética , Compostos Organometálicos/farmacocinética , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Receptores de Somatostatina/metabolismo , Distribuição TecidualRESUMO
Gastrin-releasing peptide receptors (GRPRs) are promising targets in oligometastatic prostate cancer. We have recently used 55Co (T1/2 = 17.5 h) as a label for next day PET imaging of GRPR expression obtaining high imaging contrast. The radionuclide-chelator combination can significantly influence the biodistribution of radiopeptides. Therefore, in this study, we hypothesized that the properties of 55Co-labeled PEG2-RM26 can be improved by identifying the optimal macrocyclic chelator. All analogues (X-PEG2-RM26, X = NOTA,NODAGA,DOTA,DOTAGA) were successfully labeled with radiocobalt with high yields and demonstrated high stability. The radiopeptides bound specifically and with picomolar affinity to GRPR and their cellular processing was characterized by low internalization. The best binding capacity was found for DOTA-PEG2-RM26. Ex vivo biodistribution in PC-3 xenografted mice was characterized by rapid blood clearance via renal excretion. Tumor uptake was similar for all conjugates at 3 h pi, exceeding the uptake in all other organs. Higher kidney uptake and longer retention were associated with N-terminal negative charge (DOTAGA-containing conjugate). Tumor-to-organ ratios increased over time for all constructs, although significant chelator-dependent differences were observed. Concordant with affinity measurements, DOTA-analog had the best retention of activity in tumors, resulting in the highest tumor-to-blood ratio 24 h pi, which translated into high contrast PET/CT imaging (using 55Co).
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Bombesina/farmacocinética , Radioisótopos de Cobalto/farmacocinética , Compostos Macrocíclicos/química , Compostos Organometálicos/química , Tomografia por Emissão de Pósitrons/métodos , Neoplasias da Próstata/patologia , Receptores da Bombesina/antagonistas & inibidores , Animais , Apoptose , Bombesina/análogos & derivados , Bombesina/farmacologia , Proliferação de Células , Quelantes/química , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Neurotransmissores/química , Neurotransmissores/farmacocinética , Neurotransmissores/farmacologia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND AND MOTIVATION: While small molecules can be used in cancer diagnosis there is a need for imageable diagnostic NanoParticles (NPs) that act as surrogates for the therapeutic NPs. Many NPs are composed of hydrophobic materials so the challenge is to formulate hydrophobic imaging agents. To develop individualized medical treatments based on NP, a first step should be the selection of patients who are likely responders to the treatment as judged by imaging tumor accumulation of NPs. This requires NPs with the same size and structure as the subsequent therapeutic NPs but labelled with a long-lived radionuclide. Cobalt isotopes are good candidates for NP labelling since 55Co has half-life of 17.5â¯h and positron energy of 570â¯keV while 57Co (t1/2 271.6 d) is an isotope suited for preclinical single photon emission tomography (SPECT) to visualize biodistribution and pharmacokinetics of NPs. We used the hydrophobic octaethyl porphyrin (OEP) to chelate cobalt and to encapsulate it inside hydrophobic liquid NPs (LNPs). We hypothesized that at least two additional hydrophobic axial ligands (oleylamine, OA) must be provided to the OEP-Co complex in order to encapsulate and retain Co inside LNP. RESULTS: 1. Cobalt chelation by OEP and OA. The association constant of cobalt to OEP was 2.49â¯×â¯105 M-1 and the formation of the hexacoordinate complex OEP-Co-4OA was measured by spectroscopy. 2. NP formulation and characterization: LNPs were prepared by the fast ethanol injection method and were composed of a liquid core (triolein) surrounded by a lipid monolayer (DSPC:Cholesterol:DSPE-PEG2000). The size of the LNPs loaded with the cobalt complex was 40⯱â¯5â¯nm, 3. Encapsulation of OEP-Co-OA: The loading capacity of OEP-Co-OA in LNP was 5â¯mol%. 4. Retention of OEP-57Co-4OA complex in the LNPs: the positive effect of the OA ligands was demonstrated on the stability of the OEP-57Co-4OA complex, providing a half-life for retention in PBS of 170â¯h (7â¯days) while in the absence of the axial OA ligands was only 22â¯h. 5 Biodistribution Study: the in vivo biodistribution of LNP was studied in AR42J pancreatic tumor-bearing mice. The estimated half-life of LNPs in blood was about 7.2â¯h. Remarkably, the accumulation of LNPs in the tumor was as high as 9.4% ID/g 24â¯h after injection with a doubling time for tumor accumulation of 3.22â¯h. The most important result was that the nanoparticles could indeed accumulate in the AR42J tumors up to levels greater than those of other NPs previously measured in the same tumor model, and at about half the values reported for the molecular agent 57Co-DOTATATE. CONCLUSIONS: The additional hydrophobic chelator OA was indeed needed to obtain a stable octahedral OEP-Co-4OA. Cobalt was actually well-retained inside LNP in the OEP-Co-4OA complex. The method described in the present work for the core-labelling of LNPs with cobalt is now ready for labeling of NPs with 55Co, or indeed other hexadentate radionuclides of interest for preclinical in vivo PET-imaging and radio-therapeutics.
Assuntos
Aminas/análise , Quelantes/análise , Radioisótopos de Cobalto/análise , Nanopartículas/análise , Neoplasias/diagnóstico por imagem , Porfirinas/análise , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Aminas/farmacocinética , Animais , Quelantes/farmacocinética , Radioisótopos de Cobalto/farmacocinética , Interações Hidrofóbicas e Hidrofílicas , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Porfirinas/farmacocinética , Distribuição TecidualRESUMO
High gastrin releasing peptide receptor (GRPR) expression is associated with numerous cancers including prostate and breast cancer. The aim of the current study was to develop a 55Co-labeled PET agent based on GRPR antagonist RM26 for visualization of GRPR-expressing tumors. Labeling with 57Co and 55Co, stability, binding specificity, and in vitro and in vivo characteristics of 57Co-NOTA-PEG2-RM26 were studied. NOTA-PEG2-RM26 was successfully radiolabeled with 57Co and 55Co with high yields and demonstrated high stability. The radiopeptide showed retained binding specificity to GRPR in vitro and in vivo. 57Co-NOTA-PEG2-RM26 biodistribution in mice was characterized by rapid clearance of radioactivity from blood and normal non-GRPR-expressing organs and low hepatic uptake. The clearance was predominantly renal with a low degree of radioactivity reabsorption. Tumor-to-blood ratios were approximately 200 (3 h pi) and 1000 (24 h pi). The favorable biodistribution of cobalt-labeled NOTA-PEG2-RM26 translated into high contrast preclinical PET/CT (using 55Co) and SPECT/CT (using 57Co) images of PC-3 xenografts. The initial biological results suggest that 55Co-NOTA-PEG2-RM26 is a promising tracer for PET visualization of GRPR-expressing tumors.
Assuntos
Bombesina/antagonistas & inibidores , Radioisótopos de Cobalto/farmacocinética , Tomografia por Emissão de Pósitrons/métodos , Neoplasias da Próstata/diagnóstico por imagem , Receptores da Bombesina/antagonistas & inibidores , Receptores da Bombesina/análise , Animais , Xenoenxertos , Humanos , Masculino , Camundongos , Receptores da Bombesina/metabolismo , Distribuição TecidualRESUMO
PURPOSE: Prostate-specific membrane antigen (PSMA) comprises a recognized target for molecular imaging of prostate cancer. As such, radiolabeled PSMA inhibitors are of great value for diagnosis and staging of this disease. Herein, we disclose the preclinical characterization of [55Co]PSMA-617 for positron emission tomography (PET)/x-ray computed tomography (CT) imaging of prostate cancer lesions. PROCEDURES: By the application of microwave heating, PSMA-617 in acetate buffer (0.4 M, pH 4.4) was labeled with the radioisotopes cobalt-55/57. The extents of internalization and dissociation constants (K D) were determined against 2-(phosphonomethyl)-pentanedioic acid in two PSMA-positive cell lines, LNCaP, and PC3-PIP, with [57Co]PSMA-617 as a surrogate for [55Co]PSMA-617 (T½ 17.5 h, ß max 1.5 MeV, Iß 76 %). The biodistribution in LNCaP xenograft mice was investigated using [57Co]PSMA-617 and [55Co]PSMA-617 was employed for PET/CT imaging at 1, 4, and 24 h and compared to PET/CT scans using [68Ga]PSMA-617. RESULTS: The radiolabeling with cobalt-55/57 was performed in yields greater than 99.5 and 99.8 % and radiochemical purities of 99.7 and 98.9 %, respectively. The molar-specific activities were 18.2 MBq/nmol and 3.3 MBq/nmol. The cellular K D were determined to be 4.7 nM for LNCaP and 9.8 nM for PC3-PIP, correspondingly. Internalization of 76 and 71 % of the cell-associated radioactivity was found for LNCaP and PC3-PIP cells after incubation up to 240 min, respectively. In regard to the biodistribution in LNCaP xenograft mice, [57Co]PSMA-617 displayed a high and relatively constant uptake in the tumor (12.9 %IA/g at 1 h to 10.5 %IA/g at 24 h) with an initial but transient high uptake in the kidneys, adrenals, and spleen. Tumor-to-background ratios improved over time as normal tissue cleared of the radioligand (tumor-to-blood: 26, 258, and 3013; tumor-to-kidney: 0.11, 0.28, and 4.3 at 1, 4, and 24 h). PET/CT imaging with [55Co]PSMA-617 in xenograft mice confirmed the high tumor uptake and fast clearance of normal tissues over time and was found superior to imaging with [68Ga]PSMA-617. CONCLUSION: Radiolabeling of PSMA-617 was achieved in excellent yields and radiochemical purities. Favorable in vitro data comprising low K D values and high extent of internalization was determined for two PSMA-positive cell lines. In xenograft mice, high tumor accumulation and excellent tumor-to-normal tissues ratios were established by biodistribution experiments and PET/CT imaging and, hence, confirm the potential of [55Co]PSMA-617 for delayed clinical imaging of prostate cancer.
Assuntos
Radioisótopos de Cobalto/química , Tomografia por Emissão de Pósitrons , Antígeno Prostático Específico/metabolismo , Neoplasias da Próstata/diagnóstico por imagem , Animais , Linhagem Celular Tumoral , Humanos , Ligantes , Masculino , Camundongos SCID , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Antígeno Prostático Específico/química , Neoplasias da Próstata/patologia , Distribuição Tecidual , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Several anti-cancer therapies target the epidermal growth factor receptor (EGFR). Radionuclide imaging of EGFR expression in tumours may aid in selection of optimal cancer therapy. The 111In-labelled DOTA-conjugated ZEGFR:2377 Affibody molecule was successfully used for imaging of EGFR-expressing xenografts in mice. An optimal combination of radionuclide, chelator and targeting protein may further improve the contrast of radionuclide imaging. The aim of this study was to evaluate the targeting properties of radiocobalt-labelled DOTA-ZEGFR:2377. DOTA-ZEGFR:2377 was labelled with 57Co (T1/2 = 271.8 d), 55Co (T1/2 = 17.5 h), and, for comparison, with the positron-emitting radionuclide 68Ga (T1/2 = 67.6 min) with preserved specificity of binding to EGFR-expressing A431 cells. The long-lived cobalt radioisotope 57Co was used in animal studies. Both 57Co-DOTA-ZEGFR:2377 and 68Ga-DOTA-ZEGFR:2377 demonstrated EGFR-specific accumulation in A431 xenografts and EGFR-expressing tissues in mice. Tumour-to-organ ratios for the radiocobalt-labelled DOTA-ZEGFR:2377 were significantly higher than for the gallium-labelled counterpart already at 3 h after injection. Importantly, 57Co-DOTA-ZEGFR:2377 demonstrated a tumour-to-liver ratio of 3, which is 7-fold higher than the tumour-to-liver ratio for 68Ga-DOTA-ZEGFR:2377. The results of this study suggest that the positron-emitting cobalt isotope 55Co would be an optimal label for DOTA-ZEGFR:2377 and further development should concentrate on this radionuclide as a label.
Assuntos
Complexos de Coordenação/química , Receptores ErbB/metabolismo , Compostos Heterocíclicos com 1 Anel/química , Imageamento Tridimensional , Radioisótopos/química , Proteínas Recombinantes de Fusão/metabolismo , Animais , Linhagem Celular Tumoral , Feminino , Camundongos Endogâmicos BALB C , Camundongos Nus , Tomografia por Emissão de Pósitrons , Distribuição Tecidual , Tomografia Computadorizada por Raios X , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Cancer stem cells represent the putative tumor-driving subpopulation thought to account for drug resistance, relapse, and metastatic spread of epithelial and other cancer types. Accordingly, cell surface markers for therapeutic delivery to cancer stem cells are subject of intense research. Somatostatin receptor 2 and nucleolin are known to be overexpressed by various cancer types, which have elicited comprehensive efforts to explore their therapeutic utilization. Here, we evaluated somatostatin receptor 2 targeting and nucleolin targeting for therapeutic delivery to cancer stem cells from lung cancer. Nucleolin is expressed highly but not selectively, while somatostatin receptor 2 is expressed selectively but not highly by cancer cells. The non-small cell lung cancer cell lines A549 and H1299, displayed average levels of both surface molecules as judged based on analysis of a larger cell line panel. H1299 compared to A549 cells showed significantly elevated sphere-forming capacity, indicating higher cancer stem cell content, thus qualifying as suitable test system. Nucleolin-targeting 57Co-DOTA-AS1411 aptamer showed efficient internalization by cancer cells and, remarkably, at even higher efficiency by cancer stem cells. In contrast, somatostatin receptor 2 expression levels were not sufficiently high in H1299 cells to confer efficient uptake by either non-cancer stem cells or cancer stem cells. The data provides indication that the nucleolin-targeting AS1411 aptamer might be used for therapeutic delivery to non-small cell lung cancer stem cells.
Assuntos
Aptâmeros de Nucleotídeos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Compostos Heterocíclicos com 1 Anel/química , Células-Tronco Neoplásicas/efeitos dos fármacos , Fosfoproteínas/antagonistas & inibidores , Proteínas de Ligação a RNA/antagonistas & inibidores , Receptores de Somatostatina/metabolismo , Somatostatina/análogos & derivados , Apoptose/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Proliferação de Células/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Somatostatina/farmacologia , Células Tumorais Cultivadas , NucleolinaRESUMO
Glioblastoma, the most common and malignant primary brain tumor, always recurs after standard treatment. Therefore, promising new therapeutic approaches are needed. Short-range Auger-electron-emitters carry the ability of causing highly damaging radiation effects in cells. The aim of this study was to test the effect of [125I]5-Iodo-2'-deoxyuridine (125I-UdR, a radioactive Auger-electron-emitting thymidine analogue) Auger-therapy on immature glioblastoma spheroid cultures and orthotopic xenografted glioblastoma-bearing rats, the latter by means of convection-enhanced delivery (CED). Moreover, we aimed to determine if the therapeutic effect could be enhanced when combining 125I-UdR therapy with the currently used first-line chemotherapeutic agent temozolomide. 125I-UdR significantly decreased glioblastoma cell viability and migration in vitro and the cell viability was further decreased by co-treatment with methotrexate and/or temozolomide. Intratumoral CED of methotrexate and 125I-UdR with and without concomitant systemic temozolomide chemotherapy significantly reduced the tumor burden in orthotopically xenografted glioblastoma-bearing nude rats. Thus, 100% (8/8) of the animals survived the entire observation period of 180 days when subjected to the combined Auger-chemotherapy while 57% (4/7) survived after the Auger-therapy alone. No animals (0/8) treated with temozolomide alone survived longer than 50 days. Blood samples and post-mortem histology showed no signs of dose-limiting adverse effects. In conclusion, the multidrug approach consisting of CED of methotrexate and 125I-UdR with concomitant systemic temozolomide was safe and very effective leading to 100% survival in an orthotopic xenograft glioblastoma model. Therefore, this therapeutic strategy may be a promising option for future glioblastoma therapy.