RESUMO
PURPOSE: This phase I dose-escalation study was undertaken to establish the maximum tolerated dose of the sequence-selective minor groove DNA binding agent SJG-136 in patients with advanced solid tumors. The study also investigated antitumor activity and provided pharmacokinetic and pharmacodynamic data. EXPERIMENTAL DESIGN: Sixteen patients were assigned sequentially to escalating doses of SJG-136 (15-240 microg/m(2)) given as a 10-minute i.v. infusion every 21 days. The dose was subsequently reduced in incremental steps to 45 microg/m(2) due to unexpected toxicity. RESULTS: The maximum tolerated dose of SJG-136 was 45 microg/m(2). The main drug-related adverse event was vascular leak syndrome (VLS) characterized by hypoalbuminemia, pleural effusions, ascites, and peripheral edema. Other unexpected adverse events included elevated liver function tests and fatigue. The VLS and liver toxicity had delayed onset and increased in severity with subsequent cycles. Disease stabilization was achieved for >6 weeks in 10 patients; in 2 patients this was maintained for >12 weeks. There was no evidence of DNA interstrand cross-linking in human blood lymphocytes with the use of the comet assay. Evidence of DNA interaction in lymphocytes and tumor cells was shown through a sensitive gamma-H2AX assay. SJG-136 had linear pharmacokinetics across the dose range tested. CONCLUSIONS: SJG-136 was associated with dose-limiting VLS and hepatotoxicity when administered by short injection every 21 days. DNA damage was noted, at all dose levels studied, in circulating lymphocytes. The etiology of the observed toxicities is unclear and is the subject of further preclinical research. Alternative clinical dosing strategies are being evaluated.
Assuntos
Antineoplásicos/uso terapêutico , Benzodiazepinonas/uso terapêutico , Neoplasias/tratamento farmacológico , Pirróis/uso terapêutico , Adulto , Idoso , Benzodiazepinonas/efeitos adversos , Benzodiazepinonas/farmacocinética , DNA/metabolismo , Histonas/análise , Humanos , Dose Máxima Tolerável , Pessoa de Meia-Idade , Pirróis/efeitos adversos , Pirróis/farmacocinéticaRESUMO
The welcome attitude of the 'omics community, journals and funders of research towards data sharing, coupled with successful implementations of data standards, has resulted in resource dissemination and a better understanding of many diseases, including cancer. Sharing experiment data is beneficial in terms of knowledge generation, allowing reproduction and validation of results. An adherence to a reporting guideline enables full-value extraction from costly data; this is an inexpensive method to increased quality without incurring disproportionate costs. For therapy data in particular, easy access to the range of new approaches and the ability to perform valid comparisons between these approaches would be especially useful. We discuss initiatives that support resource sharing and summarize three reporting guidelines for experiment data that have been adopted successfully. Finally, we introduce a new guideline that encompasses the diverse data types in therapeutic experiments, which is intended to be of use to the cancer therapeutics community.
Assuntos
Fidelidade a Diretrizes/normas , Guias como Assunto/normas , Informática/normas , Disseminação de Informação/métodos , Neoplasias , Animais , Humanos , Informática/métodos , Informática/organização & administraçãoRESUMO
PURPOSE: Most radioimmunotherapy studies on radiolabeled antibody distribution are based on autoradiographic and radioluminographic data, which provide a lack of detailed information due to low resolution. We used fluorescently labeled anti-carcinoembryonic antigen (CEA) antibody (A5B7) to investigate quantitatively the kinetics and microdistribution of antibody in a clinically relevant orthotopic colorectal cancer model (LS174T) using high-resolution digital microscopy. EXPERIMENTAL DESIGN: Nude mice bearing LS174T liver orthotopic tumors received a single i.v. injection of fluorescently labeled A5B7 and were sacrificed at 10 minutes, 1 hour, or 24 hours postinjection. Before sacrifice, mice were injected with the perfusion marker Hoechst 33342. An anti-CD31 antibody was used to detect blood vessel distribution. Cryostat sections were processed with immunofluorescence procedures and analyzed with fluorescence microscopy and image analysis techniques. The fluorescence images were related to morphologic images of the same or adjacent tumor sections. RESULTS: Fluorescently labeled antibody showed rapid, selective uptake into tumor deposits, with a strong negative correlation with tumor size at 10 minutes and 1 hour (P < or = 0.01). By 24 hours, the correlation was no longer significant. The study showed movement of antibody across the tumor with time and a tendency to localize more uniformly by later time points (24 hours). The rate of antibody motility was similar in small and large tumor metastases, but small deposits showed more rapid antibody localization. Intratumoral vessels were positively related to tumor size (P < or = 0.001). CONCLUSION: The obtained data suggest that radioimmunotherapy can be highly efficient in an adjuvant or minimal residual disease setting.
Assuntos
Anticorpos Antineoplásicos/metabolismo , Antígeno Carcinoembrionário/imunologia , Neoplasias Colorretais/imunologia , Neoplasias Hepáticas/secundário , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/metabolismo , Anticorpos Antineoplásicos/imunologia , Vasos Sanguíneos/metabolismo , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Neoplasias Colorretais/radioterapia , Modelos Animais de Doenças , Corantes Fluorescentes , Humanos , Neoplasias Hepáticas/imunologia , Neoplasias Hepáticas/metabolismo , Camundongos , Microscopia de Fluorescência , Metástase Neoplásica , RadioimunoterapiaRESUMO
PURPOSE: The efficacy of solid tumor radioimmunotherapy is reduced by heterogeneous tumor distribution of the radionuclide, with dose mainly deposited in the normoxic region and by the relative radioresistance of hypoxic tumor cells. In an attempt to overcome these challenges, radioimmunotherapy was combined with 2-deoxy-d-glucose (2DG), a hypoxia-selective cytotoxic inhibitor of glucose metabolism. EXPERIMENTAL DESIGN: In vitro toxicity of 2DG in LS174T cultures was tested using a colony-forming assay. The effect of combining 2DG with radioimmunotherapy in vivo was tested by administering radiolabeled anti-carcinoembryonic antigen antibody ([(131)I]A5B7 IgG1 whole monoclonal) to nude mice bearing s.c. LS174T tumors, followed by 10 daily injections of 2DG (2.0 g/kg). Tumors were measured to assess therapeutic efficacy. RESULTS: Data from in vitro studies confirmed 2DG cytotoxicity in this cell line. Greater toxicity was observed under standard laboratory conditions and in hypoxic cultures than at intermediate, physiologically relevant levels of glucose and oxygen. Alone, 2DG had no effect on in vivo tumor growth (P = 0.377 compared with saline-treated controls). Combination of radioimmunotherapy with 2DG reduced the therapeutic effect of radioimmunotherapy (e.g., 150 microCi (131)I alone mean survival time, 48.33 +/- 16.83 days; combined with 2DG, 30.67 +/- 5.62 days, P = 0.038). CONCLUSIONS: The combination investigated had a detrimental effect on survival. It is suggested that a cellular metabolic response to more aggressive therapy, previously reported in vitro, caused this. The results of this study have implications for the clinical application of combined cancer therapies with an antimetabolic modality component.
Assuntos
Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/radioterapia , Hipóxia Celular , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/radioterapia , Desoxiglucose/uso terapêutico , Radioimunoterapia/métodos , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Animais , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Neoplasias do Colo/mortalidade , Neoplasias do Colo/patologia , Terapia Combinada/efeitos adversos , Desoxiglucose/efeitos adversos , Feminino , Humanos , Camundongos , Camundongos Nus , Radioimunoterapia/efeitos adversos , Análise de Sobrevida , Carga Tumoral/efeitos dos fármacos , Carga Tumoral/efeitos da radiação , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: Antibody-directed enzyme prodrug therapy is a two-stage treatment whereby a tumor-targeted antibody-enzyme complex localizes in tumor for selective conversion of prodrug. The purpose of this study was to establish optimal variables for single administration of MFECP1, a recombinant antibody-enzyme fusion protein of an anti-carcinoembryonic antigen single-chain Fv antibody and the bacterial enzyme carboxypeptidase G2 followed by a bis-iodo phenol mustard prodrug. MFECP1 is manufactured in mannosylated form to facilitate normal tissue elimination. EXPERIMENTAL DESIGN: Pharmacokinetic, biodistribution, and tumor localization studies were used to test the hypothesis that MFECP1 localizes in tumor and clears from normal tissue via the liver. Firstly, safety of MFECP1 and a blood concentration of MFECP1 that would avoid systemic prodrug activation were tested. Secondly, dose escalation of prodrug was done. Thirdly, the dose of MFECP1 and timing of prodrug administration were optimized. RESULTS: MFECP1 was safe and well tolerated, cleared rapidly via the liver, and was less immunogenic than previously used products. Eighty-fold dose escalation from the starting dose of prodrug was carried out before dose-limiting toxicity occurred. Confirmation of the presence of enzyme in tumor and DNA interstrand cross-links indicating prodrug activation were obtained for the optimal dose and time point. A total of 28 of 31 patients was evaluable for response, the best response being a 10% reduction of tumor diameter, and 11 of 28 patients had stable disease. CONCLUSIONS: Optimal conditions for effective therapy were established. A study testing repeat treatment is currently being undertaken.
Assuntos
Mostarda de Anilina/análogos & derivados , Antígeno Carcinoembrionário/imunologia , Neoplasias Colorretais/tratamento farmacológico , Pró-Fármacos/uso terapêutico , Proteínas Recombinantes de Fusão/uso terapêutico , gama-Glutamil Hidrolase/uso terapêutico , Idoso , Mostarda de Anilina/sangue , Mostarda de Anilina/farmacocinética , Mostarda de Anilina/uso terapêutico , Anticorpos Monoclonais/sangue , Anticorpos Monoclonais/uso terapêutico , Antineoplásicos/sangue , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapêutico , Relação Dose-Resposta a Droga , Feminino , História do Século XVI , História do Século XVII , Humanos , Imageamento Tridimensional , Imunoconjugados/sangue , Imunoconjugados/farmacocinética , Imunoconjugados/uso terapêutico , Masculino , Pró-Fármacos/efeitos adversos , Pró-Fármacos/farmacocinética , Proteínas Recombinantes de Fusão/sangue , Proteínas Recombinantes de Fusão/farmacocinética , gama-Glutamil Hidrolase/sangue , gama-Glutamil Hidrolase/farmacocinéticaRESUMO
The biological basis of cancer is progressively being demonstrated at a molecular level and it is possible to model the process of cancer and identify the points at which therapeutics can operate. With this knowledge of function, it is no longer satisfactory to assess response to therapy simply by change in dimensions of cancer. Genomic and proteomic analysis adds to conventional pharmacokinetics and pharmacodynamics in preclinical models and at selected points in clinical development but advances in functional imaging make this a key tool for assessing response to therapy. Functional analyses of computed tomography (CT) and magnetic resonance imaging (MRI) images can add important information about tumour patho-physiology and positron emission tomography (PET) and single photon emission tomography (SPECT) imaging make it possible to study the distribution and therapeutic function of drugs. Together these advances will improve clinical practice and facilitate effective and safe drug development.
Assuntos
Antineoplásicos/uso terapêutico , Avaliação Pré-Clínica de Medicamentos/métodos , Neoplasias/tratamento farmacológico , Animais , Animais Domésticos , Antineoplásicos/efeitos adversos , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Avaliação Pré-Clínica de Medicamentos/tendências , Genômica , Humanos , Imageamento por Ressonância Magnética , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Proteômica , Tomografia Computadorizada de Emissão de Fóton Único , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
PURPOSE: Antibody-directed enzyme prodrug therapy (ADEPT) requires highly selective antibody-mediated delivery of enzyme to tumor. MFE-CP, a multifunctional genetic fusion protein of antibody and enzyme, was designed to achieve this by two mechanisms. First by using a high affinity and high specificity single chain Fv antibody directed to carcinoembryonic antigen. Second by rapid removal of antibody-enzyme from normal tissues by virtue of post-translational mannosylation. The purpose of this paper is to investigate these dual functions in an animal model of pharmacokinetics, pharmacodynamics, toxicity, and efficacy. EXPERIMENTAL DESIGN: MFE-CP was expressed in the yeast Pichia pastoris and purified via an engineered hexahistidine tag. Biodistribution and therapeutic effect of a single ADEPT cycle (1,000 units/kg MFE-CP followed by 70 mg/kg ZD2767P prodrug at 6, 7, and 8 hours) and multiple ADEPT cycles (9-10 cycles within 21-24 days) was studied in established human colon carcinoma xenografts, LS174T, and SW1222. RESULTS: Selective localization of functional enzyme in tumors and rapid clearance from plasma was observed within 6 hours, resulting in tumor to plasma ratios of 1,400:1 and 339:1, respectively for the LS174T and SW1222 models. A single ADEPT cycle produced reproducible tumor growth delay in both models. Multiple ADEPT cycles significantly enhanced the therapeutic effect of a single cycle in the LS174T xenografts (P = 0.001) and produced regressions in the SW1222 xenografts (P = 0.0001), with minimal toxicity. CONCLUSIONS: MFE-CP fusion protein, in combination with ZD2767P, provides a new and successful ADEPT system, which offers the potential for multiple cycles and antitumor efficacy. These results provide a basis for the next stage in clinical development of ADEPT.
Assuntos
Antígeno Carcinoembrionário/imunologia , Neoplasias do Colo/terapia , Manose/metabolismo , Compostos de Mostarda Nitrogenada/uso terapêutico , Pró-Fármacos/uso terapêutico , Proteínas Recombinantes de Fusão/uso terapêutico , gama-Glutamil Hidrolase/metabolismo , Animais , Neoplasias do Colo/diagnóstico por imagem , Neoplasias do Colo/metabolismo , Feminino , Humanos , Fragmentos de Imunoglobulinas/genética , Fragmentos de Imunoglobulinas/metabolismo , Taxa de Depuração Metabólica , Camundongos , Camundongos Nus , Compostos de Mostarda Nitrogenada/farmacocinética , Pichia/metabolismo , Pró-Fármacos/farmacocinética , Engenharia de Proteínas , Processamento de Proteína Pós-Traducional , Cintilografia , Proteínas Recombinantes de Fusão/farmacocinética , Distribuição Tecidual , Transplante Heterólogo , gama-Glutamil Hidrolase/genéticaRESUMO
Carcinoembryonic antigen (CEA) is a seven domain membrane glycoprotein widely used as a tumour marker for adenocarcinomas and as a target for antibody-directed therapies. Structural models have proposed that the first two domains of CEA (the N terminal and adjoining A1 domains) bind MFE-23, a single chain Fv antibody in experimental clinical use. We aimed to produce recombinant N-A1 to test this hypothesis. The N-A1 domains were expressed as soluble protein with a C-terminal hexahistidine tag (His6-tag) in the yeast Pichia pastoris. His6-tagged N-A1 was captured from the supernatant by batch purification with copper-loaded Streamline Chelating, an immobilised metal affinity chromatography (IMAC) matrix usually utilised in expanded bed techniques. Purified N-A1 was heterogeneous with a molecular weight range from 38 to 188 kDa. Deglycosylation with endoglycosidase H (Endo H) resulted in three discrete molecular weight forms of N-A1, one partially mannosylated, one fully Endo H-digested and one fully Endo H-digested but lacking the His6-tag. These were separated by concanavalin A chromatography followed by HiTrap IMAC. The procedure resulted in single-band-purity, mannose-free N-A1. The binding interaction of MFE-23 to N-A1 was analysed by surface plasmon resonance. The affinity constants retrieved were KD = 4.49 x 10(-9)M for the P. pastoris expressed, native N-A1, and 5.33 x 10(-9) M for the Endo H-treated N-A1. To our knowledge this is the first time that two consecutive domains of CEA have been stably expressed and purified from P. pastoris. This work confirms that the CEA epitope recognised by MFE-23 resides in N-A1.
Assuntos
Biomarcadores Tumorais/química , Antígeno Carcinoembrionário/química , Manosil-Glicoproteína Endo-beta-N-Acetilglucosaminidase/química , Pichia , Proteínas Recombinantes de Fusão/química , Adenocarcinoma/metabolismo , Biomarcadores Tumorais/biossíntese , Biomarcadores Tumorais/isolamento & purificação , Antígeno Carcinoembrionário/biossíntese , Antígeno Carcinoembrionário/isolamento & purificação , Cromatografia Líquida , Glicosilação , Humanos , Pichia/química , Pichia/metabolismo , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/isolamento & purificaçãoRESUMO
Combretastatin A-4 phosphate (CA4-P) is an antivascular agent which inhibits tumour blood flow. The effects of CA4-P were studied at 1 and 24h in colorectal xenografts by the concomitant imaging of multiple physiological parameters (hypoxia, blood vessels and perfusion), selected to demonstrate changes related to vascular shut-down. Untreated tumours were viable, with perfused blood vessels throughout and only small areas of hypoxia. At 1h post-treatment, although blood vessels remained throughout the tumour, perfused vessels were mainly restricted to the rim. However, hypoxia was widespread in both peripheral and central parts of the tumour. Quantitative analysis also revealed a significant decrease in perfusion and a maximum increase in hypoxia at this time-point. Conversely, at 24h after treatment, when most of the tumour was necrotic, pathophysiological conditions in the surviving viable rim were already returning to normal: perfusion was increasing, and hypoxia was greatly reduced and restricted to regions bordering central necrosis. In conclusion, these data provide an insight into the actions by which CA4-P may exert its effects on solid tumours.
Assuntos
Inibidores da Angiogênese/uso terapêutico , Antineoplásicos Fitogênicos/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Estilbenos/uso terapêutico , Animais , Hipóxia Celular/efeitos dos fármacos , Neoplasias Colorretais/irrigação sanguínea , Imunofluorescência , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Transplante HeterólogoRESUMO
MFE-23 is a single chain Fv (scFv) antibody molecule used to target colorectal cancer through its high affinity for the tumour marker carcinoembryonic antigen (CEA). ScFv molecules are formed from peptide-linked antibody V(H) and V(L) domains, and many of these form dimers. Our recent crystal structure for MFE-23 showed that this formed an unusual symmetric back-to-back association of two monomers that is consistent with a domain-swapped diabody structure. Neutron scattering and modelling fits showed that MFE-23 existed as compact V(H)-V(L)-linked monomers at therapeutically relevant concentrations below 1 mg/ml. Size-exclusion gel chromatography showed that the monomeric and dimeric forms of MFE-23 could be separated, and that the proportions of these two forms depended on the starting MFE-23 concentration. Sedimentation equilibrium experiments by analytical ultracentrifugation at nine concentrations of MFE-23 indicated a reversible monomer-dimer self-association equilibrium with an association constant of 1.9x10(3)-2.2x10(3) M(-1). Sedimentation velocity experiments using the time derivative g(s(*)) method showed that MFE-23-His has a concentration-dependent weight average sedimentation coefficient that increased from 1.8 S for the monomer to about 3-6 S for the dimer. Both values agreed with those calculated from the MFE-23 crystal structure. In relation to the thermal stability of MFE-23, denaturation experiments by (1)H NMR and FT-IR spectroscopy showed that the molecule is stable up to 47 degrees C, after which denaturation was irreversible. MFE-23 dimerisation is discussed in terms of a new model for diabody structures, in which the V(H) and V(L) domains in the monomer are able to dissociate and reassociate to form a dimer, or diabody, but in which symmetric back-to-back contacts between the two monomers are formed. This dimerisation in solution is attributed to the complementary nature of the C-terminal surface of the MFE-23 monomer. Crystal structures for seven other scFv molecules have shown that, while the contact residues for symmetric back-to-back dimer formation in MFE-23 are not fully conserved, in principle, back-to-back contacts can be formed in these too. This offers possibilities for the creation of other forms of scFv molecules.
Assuntos
Antineoplásicos/metabolismo , Fragmentos de Imunoglobulinas/metabolismo , Sequência de Aminoácidos , Antineoplásicos/química , Dimerização , Humanos , Fragmentos de Imunoglobulinas/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Dados de Sequência Molecular , Nêutrons , Estrutura Quaternária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , UltracentrifugaçãoRESUMO
Antibody-directed enzyme prodrug therapy has demonstrated feasibility as a treatment for cancer. Numerous prodrug/drug systems have been developed for activation by a variety of enzymes and although many have shown potential in preclinical studies, so far only one system has progressed to the clinic. Clinical studies have identified issues that were not readily apparent in xenograft models, however, these have not been addressed in the development and testing of new prodrugs. The issue of immunogenicity arising from the use of non-human enzymes has also been a major hurdle. The development of recombinant fusion proteins provides reproducible and effective antibody-enzyme products that retain the necessary specificity for prodrug activation. Advances in molecular, structural and systems biology, in combination with bioinformatics, have allowed these molecules to be readily manipulated to provide the desired characteristics.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Enzimas/administração & dosagem , Neoplasias/tratamento farmacológico , Pró-Fármacos/uso terapêutico , Proteínas Recombinantes de Fusão/uso terapêutico , Animais , Anticorpos Monoclonais/imunologia , Antígenos de Neoplasias/imunologia , Sistemas de Liberação de Medicamentos , Enzimas/metabolismo , Humanos , Pró-Fármacos/administração & dosagem , Proteínas Recombinantes de Fusão/administração & dosagemRESUMO
An scFv has been engineered to bind carcinoembryonic antigen (CEA) with a dissociation half-time >4 days at 37 degrees C. Two mutations responsible for this affinity increase were isolated by screening yeast surface-displayed mutant libraries by flow cytometry. Soluble expression of the mutant scFv in a yeast secretion system was increased 100-fold by screening mutant libraries for improved yeast surface display level. This scFv will be useful as a limiting case for evaluating the significance of affinity in tumor targeting to non-internalizing antigens.
Assuntos
Antígeno Carcinoembrionário/imunologia , Evolução Molecular Direcionada , Temperatura Alta , Fragmentos de Imunoglobulinas/genética , Fragmentos de Imunoglobulinas/imunologia , PlasmídeosRESUMO
PURPOSE: Tumor heterogeneity necessitates the use of combined therapies. We have shown that combining antibody-directed therapy with antivascular agents converts a subcurative to a curative treatment. The purpose of this study was to investigate, by radioluminographic and microscopic techniques, the regional effects of the two complementary therapies. METHODS AND MATERIALS: Nude mice bearing colorectal tumors were injected with 125I-labeled anti-carcinoembryonic antigen antibody, and images were obtained for antibody distribution and modeling studies using radioluminography. For therapy studies, the mice were given radioimmunotherapy alone (131I-A5B7 anti-carcinoembryonic antigen antibody), the antivascular agent combretastatin A-4 3-0-phosphate (200 mg/kg), or both. Extra mice were used to study the regional tumor effects of these therapies over time: relevant histochemical procedures were performed on tissue sections to obtain composite digital microscopic images of apoptosis, blood vessels, perfusion, hypoxia, and morphology. RESULTS: Antibody distribution, modeling, and immunohistochemistry showed how radioimmunotherapy (7.4 MBq/40 microg antibody) effectively treated the outer, well-oxygenated tumor region only. Combretastatin A-4 3-0-phosphate treated the more hypoxic center, and in doing so altered the relationship between tumor parameters. CONCLUSION: The combined complementary therapies produced cures by destroying tumor regions with different pathophysiologies. Relating these regional therapeutic effects to the relevant tumor parameters microscopically allows optimization of therapy and improved translation to clinical trials.
Assuntos
Inibidores da Angiogênese/uso terapêutico , Neoplasias/irrigação sanguínea , Neovascularização Patológica , Animais , Terapia Combinada , Imunoglobulina G/metabolismo , Camundongos , Camundongos Nus , Microscopia de Fluorescência , Transplante de Neoplasias , Neoplasias/imunologia , Neoplasias/patologia , Radioimunoterapia , Fatores de Tempo , Células Tumorais CultivadasRESUMO
UNLABELLED: It has been shown in vitro that the cell uptake of (18)F-FDG, a tracer of glucose metabolism, increases under hypoxia. This is consistent with increased glycolytic metabolism. We have previously shown that in ischemic heart ex vivo the rates of uptake of (18)F-FDG and 2-(14)C-deoxy-D-glucose ((14)C-2DG) are both reduced. In this study, we investigated this effect in tumors by comparing the microdistribution of (18)F-FDG and (14)C-2DG in hypoxic and normoxic regions. METHODS: Mice (MF1) bearing LS174T human tumor xenografts were injected with premixed (18)F-FDG (100 MBq), (14)C-2DG (0.37 MBq), and pimonidazole hydrochloride (60 mg/kg). After 30, 60, and 120 min, tissues (n = 4) were taken and counted for whole-body biodistribution. Tumors were frozen, sectioned, and exposed to phosphor image plates to obtain a quantitative digital image of radionuclide distribution. Sections were then stained to reveal tumor pathophysiology: Hematoxylin and eosin staining demonstrated viable and necrotic regions, and immunohistochemical staining detected pimonidazole metabolism in hypoxic cells. The images of radionuclide microdistribution and histology were then coregistered and analyzed to assess radionuclide trapping throughout the tumor on a pixel-by-pixel basis. The Pearson correlation coefficients between the 2 radionuclides were calculated. The relative amounts of nuclide were then analyzed in viable and necrotic regions and in normoxic and hypoxic regions. RESULTS: Whole-body biodistributions for the 2 radiotracers were similar. A high Pearson correlation coefficient was obtained for the 2 radionuclides throughout the tumors (r = 0.85 +/- 0.10, P < 0.0001), indicating a highly similar microdistribution. When the tumors were divided into viable and necrotic regions, the ratio of mean counts per pixel was 1.96 (P < 0.0001), whereas for hypoxic versus normoxic regions it was 1.26 (P < 0.0001). There was no significant difference in selectivity for hypoxia between the 2 radiotracers (P = 0.86). CONCLUSION: The tumor microdistribution of deoxyglucose in viable, hypoxic, and necrotic regions show that there was little change in the microdistribution of deoxyglucose throughout this time course. This study extends previous in vitro work and confirms the selectivity of deoxyglucose for viable cells over necrotic regions and for hypoxic cells over normoxic regions in vivo.
Assuntos
Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/metabolismo , Desoxiglucose/farmacocinética , Fluordesoxiglucose F18/farmacocinética , Contagem Corporal Total , Adenocarcinoma/classificação , Adenocarcinoma/patologia , Animais , Radioisótopos de Carbono , Hipóxia Celular , Linhagem Celular Tumoral , Sobrevivência Celular , Feminino , Glucose/metabolismo , Humanos , Taxa de Depuração Metabólica , Camundongos , Transplante de Neoplasias , Especificidade de Órgãos , Cintilografia , Compostos Radiofarmacêuticos/farmacocinética , Distribuição Tecidual , Transplante HeterólogoRESUMO
The therapeutic efficacy of radiolabeled antibody fragments can be limited by nephrotoxicity, particularly when the kidney is the major route of extraction from the circulation. Conventional dose estimates in kidney assume uniform dose deposition, but we have shown increased antibody localization in the cortex after glomerular filtration. The purpose of this study was to measure the radioactivity in cortex relative to medulla for a range of antibodies and to assess the validity of the assumption of uniformity of dose deposition in the whole kidney and in the cortex for these antibodies with a range of radionuclides. Storage phosphor plate technology (radioluminography) was used to acquire images of the distributions of a range of antibodies of various sizes, labeled with 125I, in kidney sections. This allowed the calculation of the antibody concentration in the cortex relative to the medulla. Beta-particle point dose kernels were then used to generate the dose-rate distributions from 14C, 131I, 186Re, 32P and 90Y. The correlation between the actual dose-rate distribution and the corresponding distribution calculated assuming uniform antibody distribution throughout the kidney was used to test the validity of estimating dose by assuming uniformity in the kidney and in the cortex. There was a strong inverse relationship between the ratio of the radioactivity in the cortex relative to that in the medulla and the antibody size. The nonuniformity of dose deposition was greatest with the smallest antibody fragments but became more uniform as the range of the emissions from the radionuclide increased. Furthermore, there was a strong correlation between the actual dose-rate distribution and the distribution when assuming a uniform source in the kidney for intact antibodies along with medium- to long-range radionuclides, but there was no correlation for small antibody fragments with any radioisotope or for short-range radionuclides with any antibody. However, when the cortex was separated from the whole kidney, the correlation between the actual dose-rate distribution and the assumed dose-rate distribution, if the source was uniform, increased significantly. During radioimmunotherapy, the extent of nonuniformity of dose deposition in the kidney depends on the properties of the antibody and radionuclide. For dosimetry estimates, the cortex should be taken as a separate source region when the radiopharmaceutical is small enough to be filtered by the glomerulus.
Assuntos
Anticorpos Monoclonais/farmacocinética , Rim/efeitos da radiação , Radioimunoterapia , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Relação Dose-Resposta à Radiação , Humanos , Imunoconjugados/administração & dosagem , Imunoconjugados/química , Imunoconjugados/imunologia , Imunoconjugados/farmacocinética , Córtex Renal/efeitos da radiação , Medula Renal/efeitos da radiação , Camundongos , Camundongos Nus , Peso Molecular , Transplante de Neoplasias , Radiometria , Células Tumorais CultivadasRESUMO
The development of novel, systemically administered radionuclide therapies (such as radioimmunotherapy) relies on the ability to predict dose-limiting toxicity to normal tissue. Where the kidney is the principal route of excretion of the radionuclide preparation and/or breakdown of products, nephrotoxicity may be the dose-limiting factor. Until recently, conventional (MIRD) dosimetry assumed the distribution in the kidney to be uniform. A new MIRD phantom of the kidney models it as a set of uniform suborgans. In the work described here, the assumption of uniformity of distribution and of heterogeneity of dose rate (and, thus, absorbed dose) was tested in the mouse model. In this paper, we examine the nonuniformity of distribution and the subsequent dose rate for 4 antibody preparations (IgG (150 kD), F(ab)'(2) (100 kD), Fab (50 kD) and sFv (27 kD)) labeled with 4 radionuclides ((125)I, (131)I, (186)Re, and (90)Y) of interest in radioimmunotherapy (RIT). The kidney was considered as a whole and as two suborgans (cortex and medulla), and the nonuniformity of the dose-rate distribution was measured by a correlation of modeled dose-rate distribution with the dose-rate distribution obtained for an equivalent uniform radionuclide distribution. The heterogeneity of distribution, the inter- and intra-suborgan, was seen to increase as the molecular weight of the antibodies decreased. The assumption of uniform activity distribution for the whole kidney gives a poor estimation of the distribution of the dose rate. In the cortex, the longer-range emitters smooth out the effect of heterogeneous distribution and, in mice, an assumption of uniform cortex self-dose distribution may be sufficient for simple calculations. It is unclear how much this smoothing would be relevant in the human kidney.
Assuntos
Neoplasias Colorretais/radioterapia , Rim/anatomia & histologia , Rim/efeitos da radiação , Radioisótopos/efeitos adversos , Radioisótopos/uso terapêutico , Animais , Anticorpos/análise , Anticorpos/imunologia , Neoplasias Colorretais/imunologia , Humanos , Rim/imunologia , Camundongos , Transplante de Neoplasias , Doses de Radiação , Radioimunoterapia , Radioterapia Assistida por ComputadorAssuntos
Biologia Computacional/organização & administração , Biologia Computacional/normas , Genômica/normas , Órgãos Governamentais/organização & administração , Programas Governamentais/organização & administração , Neoplasias , Pesquisa/normas , Animais , Humanos , Proteômica/normas , Reino UnidoRESUMO
The 23rd Annual Antibody Engineering, 10th Annual Antibody Therapeutics international conferences, and the 2012 Annual Meeting of The Antibody Society, organized by IBC Life Sciences with contributions from The Antibody Society and two Scientific Advisory Boards, were held December 3-6, 2012 in San Diego, CA. The meeting drew over 800 participants who attended sessions on a wide variety of topics relevant to antibody research and development. As a prelude to the main events, a pre-conference workshop held on December 2, 2012 focused on intellectual property issues that impact antibody engineering. The Antibody Engineering Conference was composed of six sessions held December 3-5, 2012: (1) From Receptor Biology to Therapy; (2) Antibodies in a Complex Environment; (3) Antibody Targeted CNS Therapy: Beyond the Blood Brain Barrier; (4) Deep Sequencing in B Cell Biology and Antibody Libraries; (5) Systems Medicine in the Development of Antibody Therapies/Systematic Validation of Novel Antibody Targets; and (6) Antibody Activity and Animal Models. The Antibody Therapeutics conference comprised four sessions held December 4-5, 2012: (1) Clinical and Preclinical Updates of Antibody-Drug Conjugates; (2) Multifunctional Antibodies and Antibody Combinations: Clinical Focus; (3) Development Status of Immunomodulatory Therapeutic Antibodies; and (4) Modulating the Half-Life of Antibody Therapeutics. The Antibody Society's special session on applications for recording and sharing data based on GIATE was held on December 5, 2012, and the conferences concluded with two combined sessions on December 5-6, 2012: (1) Development Status of Early Stage Therapeutic Antibodies; and (2) Immunomodulatory Antibodies for Cancer Therapy.