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PURPOSE: ATG-101, a bispecific antibody that simultaneously targets the immune checkpoint PD-L1 and the costimulatory receptor 4-1BB, activates exhausted T cells upon PD-L1 crosslinking. Previous studies demonstrated promising anti-tumour efficacy of ATG-101 in preclinical models. Here, we labelled ATG-101 with 89Zr to confirm its tumour targeting effect and tissue biodistribution in a preclinical model. We also evaluated the use of immuno-PET to study tumour uptake of ATG-101 in vivo. METHODS: ATG-101, anti-PD-L1, and an isotype control were conjugated with p-SCN-Deferoxamine (Df). The Df-conjugated antibodies were radiolabelled with 89Zr, and their radiochemical purity, immunoreactivity, and serum stability were assessed. We conducted PET/MRI and biodistribution studies on [89Zr]Zr-Df-ATG-101 in BALB/c nude mice bearing PD-L1-expressing MDA-MB-231 breast cancer xenografts for up to 10 days after intravenous administration of [89Zr]Zr-labelled antibodies. The specificity of [89Zr]Zr-Df-ATG-101 was evaluated through a competition study with unlabelled ATG-101 and anti-PD-L1 antibodies. RESULTS: The Df-conjugation and [89Zr]Zr -radiolabelling did not affect the target binding of ATG-101. Biodistribution and imaging studies demonstrated biological similarity of [89Zr]Zr-Df-ATG-101 and [89Zr]Zr-Df-anti-PD-L1. Tumour uptake of [89Zr]Zr-Df-ATG-101 was clearly visualised using small-animal PET imaging up to 7 days post-injection. Competition studies confirmed the specificity of PD-L1 targeting in vivo. CONCLUSION: [89Zr]Zr-Df-ATG-101 in vivo distribution is dependent on PD-L1 expression in the MDA-MB-231 xenograft model. Immuno-PET with [89Zr]Zr-Df-ATG-101 provides real-time information about ATG-101 distribution and tumour uptake in vivo. Our data support the use of [89Zr]Zr-Df-ATG-101 to assess tumour and tissue uptake of ATG-101.
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BACKGROUND: CI-8993 is a fully human IgG1κ monoclonal antibody (mAb) that binds specifically to immune checkpoint molecule VISTA (V-domain Ig suppressor of T-cell activation). Phase I safety has been established in patients with advanced cancer (NCT02671955). To determine the pharmacokinetics and biodistribution of CI-8993 in patients, we aimed to develop 89Zr-labelled CI-8993 and validate PET imaging and quantitation in preclinical models prior to a planned human bioimaging trial. METHODS: CI-8993 and human isotype IgG1 control were conjugated to the metal ion chelator p-isothiocyanatobenzyl-desferrioxamine (Df). Quality of conjugates were assessed by SE-HPLC, SDS-PAGE, and FACS. After radiolabelling with zirconium-89 (89Zr), radioconjugates were assessed for radiochemical purity, immunoreactivity, antigen binding affinity, and serum stability in vitro. [89Zr]Zr-Df-CI-8993 alone (1 mg/kg, 4.6 MBq) or in combination with 30 mg/kg unlabelled CI-8993, as well as isotype control [89Zr]Zr-Df-IgG1 (1 mg/kg, 4.6 MBq) were assessed in human VISTA knock-in female (C57BL/6 N-Vsirtm1.1(VSIR)Geno, huVISTA KI) or control C57BL/6 mice bearing syngeneic MB49 bladder cancer tumours; and in BALB/c nu/nu mice bearing pancreatic Capan-2 tumours. RESULTS: Stable constructs with an average chelator-to-antibody ratio of 1.81 were achieved. SDS-PAGE and SE-HPLC showed integrity of CI-8993 was maintained after conjugation; and ELISA indicated no impact of conjugation and radiolabelling on binding to human VISTA. PET imaging and biodistribution in MB49 tumour-bearing huVISTA KI female mice showed specific localisation of [89Zr]Zr-Df-CI-8993 to VISTA in spleen and tumour tissues expressing human VISTA. Specific tumour uptake was also demonstrated in Capan-2 xenografted BALB/c nu/nu mice. CONCLUSIONS: We radiolabelled and validated [89Zr]Zr-Df-CI-8993 for specific binding to huVISTA in vivo. Our results demonstrate that 89Zr-labelled CI-8993 is now suitable for targeting and imaging VISTA expression in human trials.
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Ephrin type-A 2 (EphA2) is a transmembrane receptor expressed in epithelial cancers. We report on a phase I dose escalation and biodistribution study of DS-8895a, an anti-EphA2 antibody, in patients with advanced EphA2 positive cancers. DS-8895a was administered at 1, 3, 10 or 20 mg/kg every 2 weeks to determine safety, pharmacokinetics and anti-tumor efficacy. All patients underwent 89Zr trace-labelled infusion of DS-8895a (89Zr-DS-8995a) positron emission tomography imaging to determine the biodistribution of DS-8895a, and correlate findings with EphA2 expression, receptor saturation and response. Nine patients were enrolled on study. Of patients enrolled, seven patients received at least one infusion of DS-8895a: four patients received 1 mg/kg dose (Cohort 1) and three patients received 3 mg/kg dose (Cohort 2). Median age was 67.0 years (range 52-81), majority male (71%), and median number of prior systemic therapies was three (range 0-8). The primary cancer diagnosis was colorectal cancer (two patients) and one patient each had gastric, head and neck, high-grade serous adenocarcinoma, lung, and pancreatic cancers. No dose-limiting toxicities or treatment-related adverse events reported. The best response for the patients in Cohort 1 was stable disease and in Cohort 2 was progressive disease. 89Zr-DS-8895a demonstrated no normal tissue uptake and specific low-grade uptake in most tumours. DS-8895a had limited therapeutic efficacy at doses evaluated and 89Zr-DS-8895a demonstrated low tumour uptake. The biodistribution data from this study were key in halting further development of DS-8895a, highlighting the importance of biodistribution studies in drug development. (Trial registration: ClinicalTrials.gov Identifier NCT02252211).
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Anticuerpos Monoclonales Humanizados , Antineoplásicos Inmunológicos , Neoplasias , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales , Anticuerpos Monoclonales Humanizados/farmacocinética , Anticuerpos Monoclonales Humanizados/uso terapéutico , Antineoplásicos , Antineoplásicos Inmunológicos/farmacocinética , Antineoplásicos Inmunológicos/uso terapéutico , Efrina-A2/inmunología , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/diagnóstico por imagen , Neoplasias/tratamiento farmacológico , Receptor EphA2/efectos de los fármacos , Distribución TisularRESUMEN
Positron emission tomography is the imaging modality of choice when it comes to the high sensitivity detection of key markers of thrombosis and inflammation, such as activated platelets. We, previously, generated a fluorine-18 labelled single-chain antibody (scFv) against ligand-induced binding sites (LIBS) on activated platelets, binding it to the highly abundant platelet glycoprotein integrin receptor IIb/IIIa. We used a non-site-specific bio conjugation approach with N-succinimidyl-4-[18F]fluorobenzoate (S[18F]FB), leading to a mixture of products with reduced antigen binding. In the present study, we have developed and characterised a novel fluorine-18 PET radiotracer, based on this antibody, using site-specific bio conjugation to engineer cysteine residues with N-[2-(4-[18F]fluorobenzamido)ethyl]maleimide ([18F]FBEM). ScFvanti-LIBS and control antibody mut-scFv, with engineered C-terminal cysteine, were reduced, and then, they reacted with N-[2-(4-[18F]fluorobenzamido)ethyl]maleimide ([18F]FBEM). Radiolabelled scFv was injected into mice with FeCl3-induced thrombus in the left carotid artery. Clots were imaged in a PET MR imaging system, and the amount of radioactivity in major organs was measured using an ionisation chamber and image analysis. Assessment of vessel injury, as well as the biodistribution of the radiolabelled scFv, was studied. In the in vivo experiments, we found uptake of the targeted tracer in the injured vessel, compared with the non-injured vessel, as well as a high uptake of both tracers in the kidney, lung, and muscle. As expected, both tracers cleared rapidly via the kidney. Surprisingly, a large quantity of both tracers was taken up by organs with a high glutathione content, such as the muscle and lung, due to the instability of the maleimide cysteine bond in vivo, which warrants further investigations. This limits the ability of the novel antibody radiotracer 18F-scFvanti-LIBS to bind to the target in vivo and, therefore, as a useful agent for the sensitive detection of activated platelets. We describe the first fluorine-18 variant of the scFvanti-LIBS against activated platelets using site-specific bio conjugation.
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Cisteína , Trombosis , Animales , Anticuerpos/metabolismo , Plaquetas/metabolismo , Cisteína/metabolismo , Maleimidas/metabolismo , Ratones , Tomografía de Emisión de Positrones/métodos , Trombosis/metabolismo , Distribución TisularRESUMEN
PURPOSE: Τhis study aimed to optimize the 89Zr-radiolabelling of bintrafusp alfa investigational drug product and controls, and perform the in vitro and in vivo characterization of 89Zr-Df-bintrafusp alfa and 89Zr-Df-control radioconjugates. METHODS: Bintrafusp alfa (anti-PD-L1 human IgG1 antibody fused to TGF-ß receptor II (TGF-ßRII), avelumab (anti-PD-L1 human IgG1 control antibody), isotype control (mutated inactive anti-PD-L1 IgG1 control antibody), and trap control (mutated inactive anti-PD-L1 human IgG1 fused to active TGF-ßRII) were chelated with p-isothiocyanatobenzyl-desferrioxamine (Df). After radiolabelling with zirconium-89 (89Zr), radioconjugates were assessed for radiochemical purity, immunoreactivity, antigen binding affinity, and serum stability in vitro. In vivo biodistribution and imaging studies were performed with PET/CT to identify and quantitate 89Zr-Df-bintrafusp alfa tumour uptake in a PD-L1/TGF-ß-positive murine breast cancer model (EMT-6). Specificity of 89Zr-Df-bintrafusp alfa was assessed via a combined biodistribution and imaging experiment in the presence of competing cold bintrafusp alfa (1 mg/kg). RESULTS: Nanomolar affinities for PD-L1 were achieved with 89Zr-Df-bintrafusp alfa and 89Zr-avelumab. Biodistribution and imaging studies in PD-L1- and TGF-ß-positive EMT-6 tumour-bearing BALB/c mice demonstrated the biologic similarity of 89Zr-Df-bintrafusp alfa and 89Zr-avelumab indicating the in vivo distribution pattern of bintrafusp alfa is driven by its PD-L1 binding arm. Competition study with 1 mg of unlabelled bintrafusp alfa or avelumab co-administered with trace dose of 89Zr-labelled bintrafusp alfa demonstrated the impact of dose and specificity of PD-L1 targeting in vivo. CONCLUSION: Molecular imaging of 89Zr-Df-bintrafusp alfa biodistribution was achievable and allows non-invasive quantitation of tumour uptake of 89Zr-Df-bintrafusp alfa, suitable for use in bioimaging clinical trials in cancer patients.
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Antígeno B7-H1 , Tomografía Computarizada por Tomografía de Emisión de Positrones , Animales , Antígeno B7-H1/metabolismo , Línea Celular Tumoral , Humanos , Factores Inmunológicos , Ratones , Ratones Endogámicos BALB C , Tomografía de Emisión de Positrones , Distribución Tisular , CirconioRESUMEN
INTRODUCTION: Tumor hypoxia is a centerpiece of disease progression mechanisms such as neoangiogenesis or aggressive hypoxia-resistant malignant cells selection that impacts on radiotherapy strategies. Early identification of regions at risk for recurrence and prognostic-based classification of patients is a necessity to devise tailored therapeutic strategies. We developed an image-based algorithm to spatially map areas of aerobic and anaerobic glycolysis (Glyoxia). METHODS: 18F-FDG and 18F-FMISO PET studies were used in the algorithm to produce DICOM-co-registered representations and maximum intensity projections combined with quantitative analysis of hypoxic volume (HV), hypoxic glycolytic volume (HGV), and anaerobic glycolytic volume (AGV) with CT/MRI co-registration. This was applied to a prospective clinical trial of 10 glioblastoma patients with post-operative, pre-radiotherapy, and early post-radiotherapy 18F-FDG and 18F-FMISO PET and MRI studies. RESULTS: In the 10 glioblastoma patients (5M:5F; age range 51-69 years), 14/18 18F-FMISO PET studies showed detectable hypoxia. Seven patients survived to complete post-radiotherapy studies. The patient with the longest overall survival showed non-detectable hypoxia in both pre-radiotherapy and post-radiotherapy 18F-FMISO PET. The three patients with increased HV, HGV, and AGV volumes after radiotherapy showed 2.8 months mean progression-free interval vs. 5.9 months for the other 4 patients. These parameters correlated at that time point with progression-free interval. Parameters combining hypoxia and glycolytic information (i.e., HGV and AGV) showed more prominent variation than hypoxia-based information alone (HV). Glyoxia-generated images were consistent with disease relapse topology; in particular, one patient had distant relapse anticipated by HV, HGV, and AGV maps. CONCLUSION: Spatial mapping of aerobic and anaerobic glycolysis allows unique information on tumor metabolism and hypoxia to be evaluated with PET, providing a greater understanding of tumor biology and potential response to therapy.
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Glioblastoma , Anciano , Fluorodesoxiglucosa F18 , Glioblastoma/diagnóstico por imagen , Glioblastoma/radioterapia , Glucólisis , Humanos , Hipoxia/diagnóstico por imagen , Persona de Mediana Edad , Misonidazol , Recurrencia Local de Neoplasia/diagnóstico por imagen , Recurrencia Local de Neoplasia/radioterapia , Tomografía de Emisión de Positrones , Estudios Prospectivos , RadiofármacosRESUMEN
PURPOSE: The aims of the study were to develop and evaluate a novel residualizing peptide for labeling internalizing antibodies with (124)I to support clinical development using immuno-positron emission tomography (PET). METHODS: The anti-epidermal growth factor receptor antibody ch806 was radiolabeled directly or indirectly with isotopes and various residualizing peptides. Azido-derivatized radiolabeled peptides were conjugated to dibenzylcyclooctyne-derivatized ch806 antibody via click chemistry. The radiochemical purities, antigen-expressing U87MG.de2-7 human glioblastoma cell-binding properties, and targeting of xenografts at 72 hours post injection of all radioconjugates were compared. Biodistribution of (124)I-PEG4-tptddYddtpt-ch806 and immuno-PET imaging were evaluated in tumor-bearing mice. RESULTS: Biodistribution studies using xenografts at 72 hours post injection showed that (131)I-PEG4-tptddYddtpt-ch806 tumor uptake was similar to (111)In-CHX-Aâ³-DTPA-ch806. (125)I-PEG4-tptddyddtpt-ch806 showed a lower tumor uptake value but higher than directly labeled (125)I-ch806. (124)I-PEG4-tptddYddtpt-ch806 was produced at 23% labeling efficiency, 98% radiochemical purity, 25.9 MBq/mg specific activity, and 64% cell binding in the presence of antigen excess. Tumor uptake for (124)I-PEG4-tptddYddtpt-ch806 was similar to (111)In-CHX-Aâ³-DTPA-ch806. High-resolution immuno-PET/magnetic resonance imaging of tumors showed good correlation with biodistribution data. CONCLUSIONS: The mixed d/l-enantiomeric peptide, dThr-dPro-dThr-dAsp-dAsp-Tyr-dAsp-dAsp-dThr-dPro-dThr, is suitable for radiolabeling antibodies with radiohalogens such as (124)I for high-resolution immuno-PET imaging of tumors and for evaluation in early-phase clinical trials.
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Anticuerpos Monoclonales/farmacocinética , Neoplasias Encefálicas/diagnóstico por imagen , Glioblastoma/diagnóstico por imagen , Péptidos/farmacocinética , Animales , Anticuerpos Monoclonales/química , Línea Celular Tumoral , Humanos , Radioisótopos de Yodo/química , Ratones , Trasplante de Neoplasias , Péptidos/química , Radiofármacos/química , Distribución Tisular , TirosinaRESUMEN
The significance of imaging hypoxia with the positron emission tomography ligand [(18) F]FMISO has been demonstrated in a variety of cancers. However, the slow kinetics of [(18) F]FMISO require a 2-h delay between tracer administration and patient scanning. Labeled chloroethyl sulfoxides have shown faster kinetics and higher contrast than [(18) F]FMISO in a rat model of ischemic stroke. However, these nitrogen mustard analogues are unsuitable for routine production and use in humans. Here, we report on the synthesis and in vitro and in vivo evaluation of a novel sulfoxide, which contains an ester moiety for hydrolysis and subsequent trapping in hypoxic cells. Non-decay corrected yields of radioactivity were 1.18 ± 0.24% (n = 27, 2.5 ± 0.5% decay corrected radiochemical yield) based on K[(18) F]F. The radiotracer did not show any defluorination and did not undergo metabolism in an in vitro assay using S9 liver fractions. Imaging studies using an SK-RC-52 tumor model in BALB/c nude mice have revealed that [(18) F]1 is retained in hypoxic tumors and has similar hypoxia selectivity to [(18) F]FMISO. Because of a three times faster clearance rate than [(18) F]FMISO from normoxic tissue, [(18) F]1 has emerged as a promising new radiotracer for hypoxia imaging.
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Radioisótopos de Flúor , Glicina/análogos & derivados , Sulfóxidos , Hipoxia Tumoral , Animales , Línea Celular Tumoral , Estabilidad de Medicamentos , Glicina/química , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Marcaje Isotópico , Ratones , Imagen Molecular , Radioquímica , Sulfóxidos/químicaRESUMEN
With the aim of preparing hypoxia-selective imaging and therapeutic agents, technetium(I) and rhenium(I) tricarbonyl complexes with pyridylhydrazone, dipyridylamine, and pyridylaminocarboxylate ligands containing nitrobenzyl or nitroimidazole functional groups have been prepared. The rhenium tricarbonyl complexes were synthesized with short reaction times using microwave irradiation. Rhenium tricarbonyl complexes with deprotonated p-nitrophenyl pyridylhydrazone ligands are luminescent, and this has been used to track their uptake in HeLa cells using confocal fluorescent microscopy. Selected rhenium tricarbonyl complexes displayed higher uptake in hypoxic cells when compared to normoxic cells. A (99m)Tc tricarbonyl complex with a dipyridylamine ligand bearing a nitroimidazole functional group is stable in human serum and was shown to localize in a human renal cell carcinoma (RCC; SK-RC-52) tumor in a mouse.
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Hipoxia , Compuestos Organometálicos/farmacocinética , Renio/farmacocinética , Tecnecio/farmacocinética , Animales , Línea Celular Tumoral , Diagnóstico por Imagen , Técnicas Electroquímicas , Células HeLa , Humanos , Ligandos , Luminiscencia , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Microscopía Fluorescente , Modelos Moleculares , Estructura Molecular , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Renio/química , Tecnecio/química , Distribución TisularRESUMEN
OBJECTIVE: Biomarkers for Alzheimer disease (AD) can detect the disease pathology in asymptomatic subjects and individuals with mild cognitive impairment (MCI), but their cognitive prognosis remains uncertain. We aimed to determine the prognostic value of ß-amyloid imaging, alone and in combination with memory performance, hippocampal atrophy, and apolipoprotein E ε4 status in nondemented, older individuals. METHODS: A total of 183 healthy individuals (age = 72.0 ± 7.26 years) and 87 participants with MCI (age = 73.7 ± 8.27) in the Australian Imaging, Biomarkers, and Lifestyle study of ageing were studied. Clinical reclassification was performed after 3 years, blind to biomarker findings. ß-Amyloid imaging was considered positive if the (11) C-Pittsburgh compound B cortical to reference ratio was ≥1.5. RESULTS: Thirteen percent of healthy persons progressed (15 to MCI, 8 to dementia), and 59% of the MCI cohort progressed to probable AD. Multivariate analysis showed ß-amyloid imaging as the single variable most strongly associated with progression. Of combinations, subtle memory impairment (Z score = -0.5 to -1.5) with a positive amyloid scan was most strongly associated with progression in healthy individuals (odds ratio [OR] = 16, 95% confidence interval [CI] = 3.7-68; positive predictive value [PPV] = 50%, 95% CI = 19-81; negative predictive value [NPV] = 94%, 95% CI = 88-98). Almost all amnestic MCI subjects (Z score ≤ -1.5) with a positive amyloid scan developed AD (OR = ∞; PPV = 86%, 95% CI = 72-95; NPV = 100%, 95% CI = 80-100). Hippocampal atrophy and ε4 status did not add further predictive value. INTERPRETATION: Subtle memory impairment with a positive ß-amyloid scan identifies healthy individuals at high risk for MCI or AD. Clearly amnestic patients with a positive amyloid scan have prodromal AD and a poor prognosis for dementia within 3 years.
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Envejecimiento/patología , Enfermedad de Alzheimer/diagnóstico , Péptidos beta-Amiloides/metabolismo , Trastornos de la Memoria/diagnóstico , Anciano , Anciano de 80 o más Años , Envejecimiento/fisiología , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Apolipoproteínas E/genética , Atrofia/patología , Australia/epidemiología , Biomarcadores , Disfunción Cognitiva/diagnóstico , Disfunción Cognitiva/genética , Disfunción Cognitiva/patología , Femenino , Hipocampo/metabolismo , Hipocampo/patología , Hipocampo/fisiopatología , Humanos , Estilo de Vida , Masculino , Trastornos de la Memoria/patología , Trastornos de la Memoria/fisiopatología , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Método Simple CiegoRESUMEN
Imaging of activated platelets using an activation specific anti-GPIIb/IIIa integrin single-chain antibody (scFvanti-LIBS) conjugated to a positron emitting copper-64 complex of a cage amine sarcophagine chelator (MeCOSar) is reported. This tracer was compared in vitro to a (64)Cu(II) complex of the scFv conjugated to another commonly used macrocycle, DOTA. The scFvanti-LIBS-MeCOSar conjugate was radiolabeled with (64)Cu(II) rapidly under mild conditions and with higher specific activity than scFvanti-LIBS-DOTA. The utility of scFvanti-LIBS-MeCOSar as a diagnostic agent was assessed in vivo in a mouse model of acute thrombosis. The uptake of scFvanti-LIBS-(64)CuMeCOSar in the injured vessel was significantly higher than the noninjured vessel. Positron emission tomography (PET) was used to show accumulation of scFvanti-LIBS-(64)CuMeCOSar with high and specific uptake in the injured vessel. ScFvanti-LIBS-(64)CuMeCOSar is an excellent tool for highly sensitive in vivo detection of activated platelets in PET and has the potential to be used for early diagnosis of acute thrombotic events.
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Plaquetas/efectos de los fármacos , Quelantes/química , Tomografía de Emisión de Positrones , Anticuerpos de Cadena Única/química , Animales , Plaquetas/metabolismo , Arterias Carótidas/fisiopatología , Cobre/química , Radioisótopos de Cobre/química , Diagnóstico por Imagen , Modelos Animales de Enfermedad , Citometría de Flujo , Compuestos Heterocíclicos con 1 Anillo/química , Inflamación , Ligandos , Espectroscopía de Resonancia Magnética , Ratones , Ratones Endogámicos BALB C , Activación Plaquetaria , Radiofármacos , Trombosis/diagnóstico , Microtomografía por Rayos XRESUMEN
The epidermal growth factor receptor (EGFR) protein is highly expressed in a range of malignancies. Although therapeutic interventions directed toward EGFR have yielded therapeutic responses in cancer patients, side effects are common because of normal-tissue expression of wild-type EGFR. We developed a novel tumor-specific anti-EGFR chimeric antibody ch806 labeled with 225Ac and evaluated its in vitro properties and therapeutic efficacy in murine models of glioblastoma and colorectal cancer. Methods: 225Ac-ch806 was prepared using different chelators, yielding [225Ac]Ac-macropa-tzPEG3Sq-ch806 and [225Ac]Ac-DOTA-dhPzPEG4-ch806. Radiochemical yield, purity, apparent specific activity, and serum stability of 225Ac-ch806 were quantified. In vitro cell killing effect was examined. The biodistribution and therapeutic efficacy of 225Ac-ch806 were investigated in mice with U87MG.de2-7 and DiFi tumors. Pharmacodynamic analysis of tumors after therapy was performed, including DNA double-strand break immunofluorescence of γH2AX, as well as immunohistochemistry for proliferation, cell cycle arrest, and apoptosis. Results: [225Ac]Ac-macropa-tzPEG3Sq-ch806 surpassed [225Ac]Ac-DOTA-dhPzPEG4-ch806 in radiochemical yield, purity, apparent specific activity, and serum stability. [225Ac]Ac-macropa-tzPEG3Sq-ch806 was therefore used for both in vitro and in vivo studies. It displayed a significant, specific, and dose-dependent in vitro cell-killing effect in U87MG.de2-7 cells. 225Ac-ch806 also displayed high tumor uptake and minimal uptake in normal tissues. 225Ac-ch806 significantly inhibited tumor growth and prolonged survival in both U87MG.de2-7 and DiFi models. Enhanced γH2AX staining was observed in 225Ac-ch806-treated tumors compared with controls. Reduced Ki-67 expression was evident in all 225Ac-ch806-treated tumors. Increased expression of p21 and cleaved caspase 3 was shown in U87MG.de2-7 and DiFi tumors treated with 225Ac-ch806. Conclusion: In glioblastoma and colorectal tumor models, 225Ac-ch806 significantly inhibited tumor growth via induction of double-strand breaks, thereby constraining cancer cell proliferation while inducing cell cycle arrest and apoptosis. These findings underscore the potential clinical applicability of 225Ac-ch806 as a potential therapy for EGFR-expressing solid tumors.
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BACKGROUND: This study investigates the use of (18)F-fluoromisonidazole (FMISO) PET-guided radiotherapy dose painting for potentially overcoming the radioresistant effects of hypoxia in head and neck squamous cell carcinoma (HNSCC). MATERIAL AND METHODS: The study cohort consisted of eight patients with HNSCC who were planned for definitive radiotherapy. Hypoxic subvolumes were automatically generated on pre-radiotherapy FMISO PET scans. Three radiotherapy plans were generated for each patient: a standard (STD) radiotherapy plan to a dose of 70 Gy, a uniform dose escalation (UDE) plan to the standard target volumes to a dose of 84 Gy, and a hypoxia dose-painted (HDP) plan with dose escalation only to the hypoxic subvolume to 84 Gy. Plans were compared based on tumor control probability (TCP), normal tissue complication probability (NTCP), and uncomplicated tumor control probability (UTCP). RESULTS: The mean TCP increased from 73% with STD plans to 95% with the use of UDE plans (p < 0.001) and to 93% with HDP plans (p < 0.001). The mean parotid NTCP increased from 26% to 44% with the use of UDE plans (p = 0.003), and the mean mandible NTCP increased from 2% to 27% with the use of UDE plans (p = 0.001). There were no statistically significant differences between any of the NTCPs between the STD plans and HDP plans. The mean UTCP increased from 48% with STD plans to 66% with HDP plans (p = 0.016) and dropped to 37% with UDE plans (p = 0.138). CONCLUSION: Hypoxia-targeted radiotherapy dose painting for head and neck cancer using FMISO PET is technically feasible, increases the TCP without increasing the NTCP, and increases the UTCP. This approach is superior to uniform dose escalation.
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Carcinoma de Células Escamosas/radioterapia , Hipoxia de la Célula , Fluorodesoxiglucosa F18 , Neoplasias de Cabeza y Cuello/radioterapia , Misonidazol/análogos & derivados , Tomografía de Emisión de Positrones , Planificación de la Radioterapia Asistida por Computador , Adulto , Anciano , Carcinoma de Células Escamosas/diagnóstico por imagen , Carcinoma de Células Escamosas/patología , Estudios de Cohortes , Estudios de Seguimiento , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Neoplasias de Cabeza y Cuello/patología , Humanos , Masculino , Persona de Mediana Edad , Modelos Biológicos , Estadificación de Neoplasias , Pronóstico , Radiofármacos , Dosificación Radioterapéutica , Radioterapia de Intensidad ModuladaRESUMEN
INTRODUCTION: Tissue transglutaminase 2 (TG2) is a calcium-dependent enzyme which cross-links proteins. It is overexpressed in many diseases and plays a key role in tissue remodeling, including cell adhesion and migration. Overexpression of TG2 in breast cancer is a marker for patients at risk of recurrence. Non-invasive imaging of TG2 can therefore play an important role in patient management. TG2 probes labeled with the positron emitters 11C and 18F have thus far not found widespread application due to purity and metabolism issues. Our approach was to radiolabel a TG2 selective, 13-mer amino acid peptide, which was modified with a 5-azidopentanoic acid group at the N-terminus via a copper free click chemistry approach. METHODS: Radiochemistry was performed and fully automated using an iPhase FlexLab module. We produced the radiolabeling synthon [18F]FBz-DBCO from [18F]SFB and DBCO-amine. After HPLC purification, [18F]FBz-DBCO was reacted with the modified peptide and the putative radiotracer purified by HPLC. In vivo imaging using the radiolabeled amine was performed in mice bearing either TG2 expressing MDA-MB-231 or non-TG2 expressing MCF-7 xenografts as negative control. Expression of the target was confirmed using immunohistochemistry and western blot techniques. RESULTS: We obtained 9 ± 2 GBq of the radiolabeled peptide from 55 ± 5 GBq of fluorine-18 in an overall synthesis time of 160 min from end of bombardment (EOB), including HPLC purification and reformulation. Small animal PET/MR imaging showed that visualization of MDA-MB-231 tumors using the radiolabeled peptide could only be achieved due to differences in clearance between tumor and surrounding tissue. In the MCF-7 xenograft model, radiotracer clearance from tumor and surrounding tissue occurred at a similar rate, thus making it impossible to visualize MCF-7 tumors. The presence of TG2 in MDA-MB-231 tumors and absence in MCF-7 tumors was confirmed by immunohistochemistry staining and western blot analysis. CONCLUSION: A fully automated synthesis of a TG2 selective, 13-amino-acid peptide modified with 5-azido pentynoic acid at the N-terminal was established using [18F]FBzDBCO as a prosthetic group. Although our results show that radiolabeled peptides have potential as imaging agents for TG2, more research needs to be performed to improve radiotracer kinetics.
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Péptidos , Proteína Glutamina Gamma Glutamiltransferasa 2 , Humanos , Ratones , Animales , Tomografía de Emisión de Positrones/métodos , Radioisótopos de Flúor , Línea Celular TumoralRESUMEN
INTRODUCTION: Anti-ASCT2 antibody drug conjugate (ADC) MEDI7247 has been under development as a potential anti-cancer therapy for patients with selected relapsed/refractory hematological malignancies and advanced solid tumors by MedImmune. Although promising efficacy was observed in the clinic, pharmacokinetic (PK) analyses observed low exposure of MEDI7247 in phase I hematological patients. To investigate the biodistribution properties of MEDI7247, MEDI7247 and control antibodies were radiolabeled with zirconium-89 and in vitro and in vivo properties characterized. METHODS: MEDI7247 (human anti-ASCT2 antibody conjugated with pyrrolobenzodiazepine (PBD)) and MEDI7519 (MEDI7247 without PBD drug conjugate) and an isotype control antibody drug conjugate construct were conjugated with p-isothiocyanatobenzyl-deferoxamine (Df) and radiolabeled with zirconium-89. In vitro studies included determining the radiochemical purity, protein integrity, immunoreactivity (Lindmo analysis), apparent antigen binding affinity for ASCT2-positive cells by Scatchard analysis and serum stability of the radiolabeled immunoconjugates. In vivo studies included biodistribution and PET/MRI imaging studies of the radiolabeled immunoconjugates in an ASCT2-positive tumor model, HT-29 colorectal carcinoma xenografts. RESULTS: Conditions for the Df-conjugation and radiolabeling of antibody constructs were determined to produce active radioimmunoconjugates. In vivo biodistribution and whole body PET/MRI imaging studies of [89Zr]Zr-Df-MEDI7519 and [89Zr]Zr-Df-MEDI7247 radioimmunoconjugates in HT-29 colon carcinoma xenografts in BALB/c nude mice demonstrated specific tumor localization. However, more rapid blood clearance and non-specific localization in liver was observed for [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 compared to isotype control ADC. Except for liver and bone, other normal tissues demonstrated clearance reflecting the blood clearance for all three constructs and no other abnormal tissue uptake. CONCLUSIONS AND ADVANCES IN KNOWLEDGE: Preclinical biodistribution analyses of [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 showed the biodistribution pattern of anti-ASCT2 ADC MEDI7247 was similar to parental MEDI7519, and both antibodies showed specific tumor uptake compared to an isotype control ADC. This study highlights an important role nuclear medicine imaging techniques can play in early preclinical assessment of drug specificity as part of the drug development pipeline.
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Neoplasias del Colon , Inmunoconjugados , Ratones , Animales , Humanos , Distribución Tisular , Inmunoconjugados/farmacocinética , Ratones Desnudos , Tomografía de Emisión de Positrones/métodos , Circonio/química , Línea Celular TumoralRESUMEN
BACKGROUND AND PURPOSE: Conflicting evidence exists as to whether focal cerebral ischemia contributes to cerebral amyloid deposition. We aimed to look at Aß deposits, detected by N-methyl-2-(4'-methylaminophenyl)-6-hydroxybenzothiazole (PiB) positron emission tomography, in patients with recent ischemic stroke. Specifically, we hypothesized that patients with recent ischemic stroke have higher local and neocortical PiB positron emission tomography retention and that this may be associated with major vascular risk factors. METHODS: Ischemic stroke patients were studied using PiB positron emission tomography within 30 days and compared to age-matched controls. Distribution volume ratio maps were created using Logan graphical analysis with the cerebellar cortex as a reference. RESULTS: Among the 21 ischemic stroke patients (median age, 76 years; interquartile range, 68-77), the ipsilateral peri-infarct region PiB retention was higher compared to the contralateral mirror region, with a PiB distribution volume ratio difference of 0.29 (95% CI, 0.2-0.44; P=0.001) at median 10 (interquartile range, 7-14) days after stroke. Two patients also had higher PiB retention within the infarct compared to the contralateral side. There was no difference in the neocortical PiB retention elsewhere in the brain among ischemic stroke patients compared with 22 age-matched normal controls (P=0.22). Among the risk factors in the ischemic stroke patients, diabetes was associated with a higher neocortical PiB retention (Spearman Rho=0.48; 95% CI, 0.28-0.72). CONCLUSIONS: PiB retention was higher in the peri-infarct region among patients with recent ischemic stroke. This did not translate into a higher global neocortical PiB retention except possibly in patients with diabetes. The cause of the focal PiB retention is uncertain and requires further investigation.
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Péptidos beta-Amiloides/metabolismo , Infarto Encefálico/metabolismo , Radioisótopos de Carbono/metabolismo , Neocórtex/metabolismo , Fenantrolinas/metabolismo , Tomografía de Emisión de Positrones , Accidente Cerebrovascular/metabolismo , Anciano , Compuestos de Anilina , Fibrilación Atrial/complicaciones , Fibrilación Atrial/metabolismo , Infarto Encefálico/diagnóstico por imagen , Infarto Encefálico/epidemiología , Estudios de Casos y Controles , Complicaciones de la Diabetes/complicaciones , Complicaciones de la Diabetes/metabolismo , Femenino , Humanos , Hiperlipidemias/complicaciones , Hiperlipidemias/metabolismo , Hipertensión/complicaciones , Hipertensión/metabolismo , Masculino , Neocórtex/diagnóstico por imagen , Factores de Riesgo , Fumar/efectos adversos , Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/epidemiología , TiazolesRESUMEN
OBJECTIVE: Assess Aß deposition longitudinally and explore its relationship with cognition and disease progression. METHODS: Clinical follow-up was obtained 20 ± 3 months after [¹¹C]Pittsburgh compound B (PiB)-positron emission tomography in 206 subjects: 35 with dementia of the Alzheimer type (DAT), 65 with mild cognitive impairment (MCI), and 106 age-matched healthy controls (HCs). A second PiB scan was obtained at follow-up in 185 subjects and a third scan after 3 years in 57. RESULTS: At baseline, 97% of DAT, 69% of MCI, and 31% of HC subjects showed high PiB retention. At 20-month follow-up, small but significant increases in PiB standardized uptake value ratios were observed in the DAT and MCI groups, and in HCs with high PiB retention at baseline (5.7%, 2.1%, and 1.5%, respectively). Increases were associated with the number of apolipoprotein E ε4 alleles. There was a weak correlation between PiB increases and decline in cognition when all groups were combined. Progression to DAT occurred in 67% of MCI with high PiB versus 5% of those with low PiB, but 20% of the low PiB MCI subjects progressed to other dementias. Of the high PiB HCs, 16% developed MCI or DAT by 20 months and 25% by 3 years. One low PiB HC developed MCI. INTERPRETATION: Aß deposition increases slowly from cognitive normality to moderate severity DAT. Extensive Aß deposition precedes cognitive impairment, and is associated with ApoE genotype and a higher risk of cognitive decline in HCs and progression from MCI to DAT over 1 to 2 years. However, cognitive decline is only weakly related to change in Aß burden, suggesting that downstream factors have a more direct effect on symptom progression.
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Envejecimiento/fisiología , Enfermedad de Alzheimer/diagnóstico , Encéfalo/patología , Trastornos del Conocimiento/diagnóstico , Cognición/fisiología , Placa Amiloide/patología , Anciano , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides , Compuestos de Anilina , Encéfalo/diagnóstico por imagen , Progresión de la Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Pruebas Neuropsicológicas , Placa Amiloide/diagnóstico , Placa Amiloide/diagnóstico por imagen , Polimorfismo Genético , Tomografía de Emisión de Positrones , Índice de Severidad de la Enfermedad , TiazolesRESUMEN
PURPOSE: Amyloid imaging with (18)F-labelled radiotracers will allow widespread use of this technique, facilitating research, diagnosis and therapeutic development for Alzheimer's disease (AD). The purpose of this analysis was to compare data on cortical Aß deposition in subjects who had undergone both (11)C-PiB (PiB) and (18)F-florbetaben (FBB) PET imaging. METHODS: We identified ten healthy elderly controls (HC) and ten patients with AD who had undergone PET imaging after intravenous injection of 370 MBq of PiB and 300 MBq of FBB under separate research protocols. PiB and FBB images were coregistered so that placement of regions of interest was identical on both scans and standard uptake value ratios (SUVR) using the cerebellar cortex as reference region were calculated between 40 and 70 min and between 90 and 110 min after injection for PiB and FBB, respectively. RESULTS: Significantly higher SUVR values (p < 0.0001) in most cortical areas were observed in AD patients when compared with HC with both radiotracers. Global SUVR values in AD patients were on average 75% higher than in HC with PiB and 56% higher with FBB. There was an excellent linear correlation between PiB and FBB global SUVR values (r = 0.97, p < 0.0001) with similar effect sizes for distinguishing AD from HC subjects for both radiotracers (Cohen's d 3.3 for PiB and 3.0 for FBB). CONCLUSION: FBB, while having a narrower dynamic range than PiB, clearly distinguished HC from AD patients, with a comparable effect size. FBB seems a suitable (18)F radiotracer for imaging AD pathology in vivo.
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Envejecimiento/metabolismo , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Compuestos de Anilina , Benzotiazoles , Tomografía de Emisión de Positrones/métodos , Estilbenos , Anciano , Compuestos de Anilina/metabolismo , Benzotiazoles/metabolismo , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estilbenos/metabolismo , TiazolesRESUMEN
The relationship between ß-amyloid deposition and memory deficits in early Alzheimer's disease is unresolved, as past studies show conflicting findings. The present study aims to determine the relative contribution of regional ß-amyloid deposition, hippocampal atrophy and white matter integrity to episodic memory deficits in non-demented older individuals harbouring one of the characteristic hallmarks of Alzheimer's disease, i.e. with ß-amyloid pathology. Understanding these relationships is critical for effective therapeutic development. Brain magnetic resonance imaging and [(11)C]Pittsburgh Compound B-positron emission tomography scans were obtained in 136 non-demented individuals aged over 60 years, including 93 healthy elderly and 43 patients with mild cognitive impairment. Voxel-based correlations were computed between a memory composite score and grey matter volume, white matter volume and ß-amyloid deposition imaging datasets. Hierarchical linear regression analyses were then performed using values extracted in regions of most significant correlations to determine the relative contribution of each modality to memory deficits. All analyses were conducted pooling all groups together as well as within separate subgroups of cognitively normal elderly, patients with mild cognitive impairment and individuals with high versus low neocortical ß-amyloid. Brain areas of highest correlation with episodic memory deficits were the hippocampi for grey matter volume, the perforant path for white matter volume and the temporal neocortex for ß-amyloid deposition. When considering these three variables together, only hippocampal volume and temporal ß-amyloid deposition provided independent contributions to memory deficits. In contrast to global ß-amyloid deposition, temporal ß-amyloid deposition was still related to memory independently from hippocampal atrophy within subgroups of cognitively normal elderly, patients with mild cognitive impairment or cases with high neocortical ß-amyloid. In the pre-dementia stage of Alzheimer's disease, subtle episodic memory impairment is related to ß-amyloid deposition, especially in the temporal neocortex, and independently from hippocampal atrophy, suggesting that both factors should be independently targeted in therapeutic trials aimed at reducing cognitive decline.