RESUMO
Background: Trastuzumab, the first humanized antibody approved for therapeutic use has shown promising results for the treatment of patients with human epidermal growth factor receptor 2 (HER2) positive cancers. The aim of this study was to formulate immunoPET agents based on trastuzumab fragments and demonstrate their potential for early diagnosis of HER2-positive tumors. Materials and Methods: F(ab')2 and F(ab') fragments of trastuzumab were prepared by enzymatic digestion and conjugated with chelator NOTA for labeling with 68Ga. For comparison, intact trastuzumab was also radiolabeled. In vitro stability, immunoreactivity, and binding affinity of radio formulations toward HER2 receptors were evaluated by performing in vitro studies in cancer cell lines. Biodistribution and PET imaging studies were performed in animal model bearing tumors. Results: 68Ga-NOTA-F(ab')-trastuzumab, 68Ga-NOTA-F(ab')2-trastuzumab, and 68Ga-NOTA-trastuzumab could be prepared with >98% radiochemical purity (% RCP) and were found to be stable when studied up to 4 h. In vitro binding studies revealed high affinity and specificity of formulations toward HER2 receptors. Specific tumor uptake of 68Ga-NOTA-F(ab')-trastuzumab and 68Ga-NOTA-F(ab')2-trastuzumab in HER2-positive tumors was observed in biodistribution and PET imaging studies. Conclusions: This study describes optimization of protocol for the formulation of 68Ga-NOTA-F(ab')-trastuzumab and 68Ga-NOTA-F(ab')2-trastuzumab for targeting HER2-overexpressing tumors. Further studies with these radioformulations are warranted to confirm their potential as immunoPET agents for management of HER2-positive breast and other solid tumors.
Assuntos
Radioisótopos de Gálio , Neoplasias , Animais , Humanos , Trastuzumab/farmacologia , Distribuição Tecidual , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológicoRESUMO
Background: Mold brachytherapy using high-energy ß--emitting radioisotopes is a promising treatment modality for skin cancers and keloids. Simple methodologies for consistent and stable incorporation of radionuclides into the matrix are desired for preparation of therapeutic sources. Methods: The authors report a facile strategy for the stable incorporation of Yttrium-90 (90Y) into amidoxime-functionalized polyacrylonitrile-polyvinylidene fluoride (PAN-PVDF) membranes. The strategy consisted of surface modification of PAN-PVDF membranes by reaction with hydroxylamine, characterization of the functionalized membranes, and optimization of experimental variables for maximum loading of 90Y onto the membranes. Quality control tests essential for confirming the suitability of the 90Y therapeutic sources for human application, such as uniformity of activity distribution, absence of leaching of activity, and estimation of surface contamination, were performed. Theoretical calculations to estimate the dose imparted by the 90Y therapeutic sources at varying depths of tissue were also carried out to predict the possible therapeutic outcome of treatment. Results: A facile method for large-scale preparation of 90Y-based mold brachytherapy sources could be established. Conclusions: The source fabrication methodology standardized in this work could be tailored for fabrication of custom-made 90Y sources for individualized treatment of superficial tumors, Bowen's disease, and keloids.
Assuntos
Braquiterapia , Queloide , Neoplasias Cutâneas , Braquiterapia/métodos , Humanos , Queloide/tratamento farmacológico , Radiometria/métodos , Radioisótopos de Ítrio/uso terapêuticoRESUMO
170Tm is being explored as a source for applications in brachytherapy. Although it has adequate physical properties, such as a short half-life (128.6 d), high specific activity and a mean photon energy of about 66 keV, it has a drawback of low photon yield (only about six photon emissions/100 beta emissions). The objective of this work is to study the dosimetric characteristics of a locally developed170Tm brachytherapy seed source using the Monte Carlo-based EGSnrc code system. In this study, we calculate the dose rate constant, air-kerma strength, radial dose function, anisotropic function and 2D dose-rate distributions in water. Separate simulations are carried out by considering the photon (gamma and characteristic x-ray) and beta spectra of the source. For regions close to the source (surface of the source Assuntos
Braquiterapia
, Partículas beta
, Método de Monte Carlo
, Fótons
, Radiometria
, Dosagem Radioterapêutica
RESUMO
BACKGROUND: Trastuzumab is a Food and Drug Administration-approved humanized monoclonal antibody which targets the extracellular domain of human epidermal growth factor receptor 2 (HER2) receptor overexpressed on HER2-positive breast cancer cells. The combination of Lutetium-177 (177 Lu) (t½= 6.7 days, Eßmax497 keV (78.6%) and trastuzumab makes it a suitable targeting agent for radioimmunotherapy. In preclinical and clinical studies,177 Lu-Trastuzumab has proven to be effective for the treatment of HER2-positive malignancies such as breast and ovarian cancer. OBJECTIVES: In this study, we report the mechanism of action of177 Lu-CHX-A"-diethylenetriaminepentaacetic acid (DTPA)-trastuzumab at the cellular and molecular level by performing various in vitro assays in HER2-positive MDA-MB-453 breast cancer cells. MATERIALS AND METHODS: Trastuzumab was conjugated to the bifunctional chelating agent (BFCA) para-isothiocyanatobenzyl-DTPA and radiolabeled with177 Lu. In vitro cell binding studies were carried out in MDA-MB-453 cells to confirm the specificity of the complex toward the receptor. Cellular toxicity, cell cycle, and cell death analysis were also performed for exploring the potential of the radioimmunoconjugate at cellular and molecular level. RESULTS: In vitro cell binding studies showed a maximum binding of 10.7 ± 0.1% which reduced to 2.9 ± 0.1% on coincubation with unlabeled antibody. Our study revealed that the cellular toxicity was dose dependent, and mode of cell death was predominantly by apoptosis. The radioimmunoconjugate retarded the cell in the S phase of cell cycle with two-fold increase in G2/M arrest which justifies the enhanced apoptosis at higher doses. CONCLUSIONS: The study revealed that the formulation can execute a dose-dependent cellular toxicity through induction of apoptosis.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Imunoconjugados/farmacologia , Lutécio/farmacologia , Compostos Organometálicos/farmacologia , Radioisótopos/farmacologia , Trastuzumab/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Humanos , Imunoconjugados/uso terapêutico , Lutécio/uso terapêutico , Compostos Organometálicos/uso terapêutico , Radioisótopos/uso terapêutico , Receptor ErbB-2/metabolismo , Trastuzumab/uso terapêuticoRESUMO
Rituximab is used for the treatment of non-Hodgkin lymphoma (NHL). This study focuses on development of 68 Ga-labeled rituximab fragments, (68 Ga-NOTA-F (ab')-rituximab and 68 Ga-NOTA-F (ab')2 -rituximab, as PET-imaging agents for NHL. Rituximab was digested with immobilized pepsin and papain to yield F (ab')2 and Fab fragments respectively that were characterized by size exclusion HPLC (SE-HPLC) and SDS-PAGE. They were conjugated with p-SCN-Bn-NOTA, labeled with 68 Ga and characterized by SE-HPLC. Intact rituximab was labeled with gallium-68 for comparison. Specificity of 68 Ga-labeled immunoconjugates was ascertained by immunoreactivity and cell binding studies in Raji cells, while biodistribution studies were performed in normal Swiss mice. Gradient SDS-PAGE under nonreducing condition showed molecular weights of F (ab')2 -rituximab and F (ab')-rituximab as approximately 100 and 40 Kd, respectively. Radiochemical purity (RCP) of 68 Ga-NOTA-F (ab')2 -rituximab and 68 Ga-NOTA-F (ab')-rituximab were 98.2 ± 0.5% and 98.8 ± 0.2% respectively with retention times of 17.1 ± 0.1 min and 19.3 ± 0.1 min in SE-HPLC. 68 Ga-labeled rituximab fragments were stable in saline and serum up to 2-hour post preparation and exhibited specificity to CD20 antigen. Immunoreactivity of 68 Ga-labeled immunoconjugates was greater than 80%. Clearance of the fragmented radioimmunoconjugates was predominantly through renal route. Preliminary results from this study demonstrate the potential of 68 Ga- NOTA-F (ab')2 -rituximab and 68 Ga-NOTA-F (ab')-rituximab as PET imaging agents for NHL.
Assuntos
Radioisótopos de Gálio/química , Compostos Heterocíclicos com 1 Anel/química , Imunoconjugados/química , Linfoma não Hodgkin/diagnóstico por imagem , Cintilografia/métodos , Rituximab/química , Animais , Linhagem Celular Tumoral , Humanos , Imunoconjugados/farmacocinética , Marcação por Isótopo , Camundongos , Distribuição TecidualRESUMO
Background: Transarterial radioembolization (TARE) represents an effective targeted therapeutic option for hepatocellular carcinoma (HCC), a cancer with high mortality and poor prognosis. The aim of this study was the preparation and preliminary biological evaluation of 177Lu-labeled polyhydroxamic acid (PHA) microparticles toward possible use in the therapy of HCC. Materials and Methods: PHA microparticles were synthesized starting from polyacrylamide. They were characterized by Fourier-transform infrared spectroscopy (FT-IR), visual color test, and laser diffraction particle size analysis. Experimental variables such as reaction pH, amount of PHA microparticles, carrier Lu content, and incubation time were optimized for maximum uptake of 177Lu on PHA microparticles. Stability of 177Lu-PHA microparticles was tested in the presence of competing Fe(III) ions in solution. In vitro stability of 177Lu-PHA microparticles was evaluated in 0.05 M sodium phosphate solution (pH 7.5), saline, and serum. Bioevaluation studies were performed in normal Wistar rats by intrahepatic artery injection of the 177Lu-PHA microparticles. Results: Successful synthesis of PHA microparticles could be confirmed from the results of FT-IR analysis and visual color test. Laser diffraction-based particle size analysis confirmed median particle size to be 54 µm, suitable for TARE. Under the optimized conditions, >99% loading of 177Lu on PHA microparticles could be achieved. Even in the presence of high concentration of Fe(III) ions, 177Lu binding to PHA microparticles was stable. 177Lu-PHA microparticles exhibited excellent in vitro stability in sodium phosphate solution, saline, and serum up to 5 d at 37°C. In the bioevaluation studies performed in normal Wistar rats, 92.8% ± 3.1% of 177Lu-PHA microparticles were retained in the liver at 96 h postinjection without any significant leakage to other organs. Conclusion: This preliminary study demonstrates the potential of synthesized PHA microparticles as carriers of therapeutic radioisotopes such as 177Lu for treatment of HCC.
Assuntos
Carcinoma Hepatocelular/radioterapia , Ácidos Hidroxâmicos/química , Neoplasias Hepáticas/radioterapia , Lutécio/farmacologia , Radioisótopos/farmacologia , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacologia , Animais , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Ratos , Ratos WistarRESUMO
The objective of this study was the facile preparation of 177Lu-CHX-A''-DTPA-Trastuzumab injection for breast cancer therapy. Trastuzumab conjugated with CHX-A''-DTPA-NCS was radiolabeled with 177Lu in >95% radiochemical purity. In vitro studies in SKBR3 and MDA-MB-453â¯cells confirmed specificity of 177Lu-CHX-A''-DTPA-Trastuzumab to HER2 positive cells. The radioimmunoconjugate showed good immunoreactivity, in vitro stability in saline and Kd of 1.01⯱â¯0.13â¯nM in SKBR3 cells. Clearance of 177Lu-CHX-A''-DTPA-Trastuzumab in Swiss mice was predominantly through the hepatobiliary route with minimal bone uptake.
Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Imunoconjugados/uso terapêutico , Lutécio/administração & dosagem , Radioisótopos/administração & dosagem , Trastuzumab/uso terapêutico , Animais , Antineoplásicos Imunológicos/administração & dosagem , Antineoplásicos Imunológicos/farmacocinética , Linhagem Celular Tumoral , Feminino , Humanos , Imunoconjugados/administração & dosagem , Lutécio/farmacocinética , Camundongos , Radioisótopos/farmacocinética , Distribuição Tecidual , Trastuzumab/administração & dosagem , Trastuzumab/farmacocinéticaRESUMO
This study was aimed at evaluating the role of bifunctional chelators DOTA-NCS and CHX-Aâ³-DTPA-NCS used for conjugating 177 Lu with Nimotuzumab on the radiochemical yields, purity, in vitro stability, and specificity of the radioimmunoconjugates to EGFR. Two immunoconjugates were prepared wherein Nimotuzumab was conjugated with the acyclic ligand p-NCS-Bn-CHX-Aâ³-DTPA and macrocyclic ligand p-NCS-Bn-DOTA. These were radiolabeled with 177 Lu, purified on PD-10 column, and characterized by SE-HPLC. In vitro stability was determined up to 4 days post preparation. Specificity of the radioimmunoconjugates was ascertained by in vitro studies in A431 cells while the biodistribution patterns were studied in normal Swiss mice up to 96 hours post injection. Four to five molecules of CHX-Aâ³-DTPA/DOTA were attached to one molecule of Nimotuzumab. Radiochemical purity of both 177 Lu-CHX-Aâ³-DTPA-Nimotuzumab and 177 Lu-DOTA-Nimotuzumab was determined to be greater than 98%. Both the radioimmunoconjugates exhibited good in vitro stability at 37°C up to 4 days post preparation in saline, and their clearance was largely by the hepatobiliary route. The DOTA- and CHX-Aâ³-DTPA-based radioimmunoconjugates could be prepared with good radiochemical purity, in vitro stability, and specificity to EGFR. Further studies in EGFR-positive cancers would pave way for them for use in the clinics.
Assuntos
Anticorpos Monoclonais Humanizados/química , Anticorpos Monoclonais Humanizados/uso terapêutico , Quelantes/química , Compostos Heterocíclicos com 1 Anel/química , Lutécio/uso terapêutico , Ácido Pentético/análogos & derivados , Radioimunoterapia , Radioisótopos/uso terapêutico , Animais , Anticorpos Monoclonais Humanizados/metabolismo , Anticorpos Monoclonais Humanizados/farmacocinética , Linhagem Celular Tumoral , Receptores ErbB/metabolismo , Humanos , Marcação por Isótopo , Camundongos , Ácido Pentético/química , Distribuição TecidualRESUMO
OBJECTIVE: This article describes the preparation of a 170Tm source by chemical deposition technique, its encapsulation in a titanium holder, and preliminary quality evaluation for potential utility as a brachytherapy source. METHODS: The procedure consisted of electrodeposition of Ni on a Cu wire followed by chemical deposition of 170Tm on it. Influence of feed solution pH, carrier Tm concentration, and reaction time were studied for optimum deposition of 170Tm on substrate. After sealing the source core in a titanium capsule, quality control tests were performed. Distribution of 170Tm on substrate was evaluated by autoradiography. Inactive Tm source was characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDS) analyses. RESULTS: Under optimized conditions (pH 5, 10 µg Tm carrier, 5 h), 170Tm source core could be prepared by deposition of >95% of 170Tm radioactivity on substrate. Swipe tests and immersion tests on encapsulated sources confirmed that removable radioactivity and radioactivity leakage levels were within stipulated limits. Autoradiography of 170Tm source confirmed uniformity of radioactivity distribution. While SEM analysis confirmed good adhesion of Tm on substrate, EDS analysis confirmed elemental constituents of the Tm-deposited substrate. CONCLUSION: The objective of preparing a 170Tm source by chemical deposition for potential brachytherapy applications could be successfully achieved.
Assuntos
Braquiterapia/instrumentação , Radioisótopos/química , Túlio/química , Autorradiografia , Braquiterapia/métodos , Cobre/química , Galvanoplastia/métodos , Concentração de Íons de Hidrogênio , Níquel/química , Garantia da Qualidade dos Cuidados de Saúde , Titânio/químicaRESUMO
Pharmaceutical grade DOTATOC kits compliant with all the quality control criteria were formulated and radiolabeled with 68Ga in high yields. Comparison with module-based 68Ga-DOTATOC established product equivalency. Clinical utility was evaluated in patients with histopathologically confirmed well-differentiated neuroendocrine tumors. Kit-based preparation of 68Ga-DOTATOC could identify sites of primary and metastatic disease. PET/CT images of patients conformed to the established criteria for somatostatin imaging agents and clinical expectations. Results of this study emphasize the potential of kit-based 68Ga-DOTATOC for PET imaging of neuroendocrine tumors.
RESUMO
The primary objective of this investigation is the development of a strategy for the synthesis of polyhydroxamic acid (PHA)-grafted cellulose film, its characterization, and evaluation of its usefulness for the preparation of 177Lu skin patches for superficial brachytherapy applications. PHA-grafted cellulose films were synthesized and characterized by Fourier transformed infrared spectrometer analysis and visual color test with Fe(III) solution. Uptake of 177Lu on the PHA-grafted cellulose was investigated by varying the experimental conditions such as the pH of feed solution, amount of nonradioactive Lu carrier, time, and temperature of the reaction. Under the optimized conditions, >95% loading of 177Lu on the PHA-cellulose film could be achieved. Autoradiography studies of 177Lu-PHA-cellulose film confirmed the uniform distribution of 177Lu on the surface. Energy dispersive X-ray analysis of nonradioactive Lu-PHA-cellulose film confirmed the loading of Lu on PHA-cellulose film. The utility of PHA-functionalized cellulose films for the fabrication of radioactive sources for superficial brachytherapy applications could be successfully demonstrated.
Assuntos
Celulose/química , Ácidos Hidroxâmicos/química , Lutécio/química , Radioisótopos/química , Neoplasias Cutâneas/radioterapia , Adesivo Transdérmico , Braquiterapia , Humanos , Lutécio/administração & dosagem , Radioisótopos/administração & dosagemRESUMO
Molecular imaging using radiolabeled Tyrosine Kinase Inhibitors (TKI) is a promising strategy for detection and staging of EGFR-positive cancers. A novel analogue of one such TKI, Erlotinib has been developed for PET imaging by derivatizing the parent Erlotinib molecule for conjugation with the bifunctional chelator p-SCN-Bn-NOTA towards radiolabeling with 68Ga. NOTA-Erlotinib conjugate was synthesized and characterized by NMR and ESI-MS techniques. The conjugate was radiolabeled with 68Ga in 95±2% yield, as evidenced by HPLC characterization. The logP value of 68Ga-NOTA-Erlotinib was - (0.6±0.1). The 68Ga-NOTA-Erlotinib conjugate was characterized using its natGa-NOTA-Erlotinib surrogate. Cell viability studies showed that the NOTA-Erlotinib conjugate retained the biological efficacy of the parent Erlotinib molecule. Further, 68Ga-NOTA-Erlotinib exhibited an uptake of 9.8±0.4% in A431 cells which was inhibited by 55.1±0.2% on addition of cold Erlotinib (10µg) confirming the specificity of the radioconjugate for EGFR expressing cells. In the biodistribution studies carried out in tumor bearing SCID mice, 68Ga-NOTA-Erlotinib conjugate showed moderate tumor accumulation (1.5±0.1% ID/g at 30minp.i.; 0.7±0.2% ID/g at 1hp.i.). Hepatobiliary clearance of the radioconjugate was observed. The 68Ga-NOTA-Erlotinib conjugate was found to have high in vivo stability as determined by the metabolite analysis study using urine sample of the Swiss mice injected with the preparation. The overall properties of 68Ga-NOTA-Erlotinib are promising and merit further exploration. To the best of our knowledge, this is the first report on the design of a 68Ga labeled Erlotinib for PET imaging of EGFR and opens avenues for the successful development of 68Ga labeled TKI for imaging of EGFR over-expressing tumors.
Assuntos
Receptores ErbB/biossíntese , Cloridrato de Erlotinib/química , Neoplasias Pulmonares/diagnóstico , Imagem Molecular , Tomografia por Emissão de Pósitrons , Neoplasias Cutâneas/diagnóstico , Animais , Cloridrato de Erlotinib/síntese química , Cloridrato de Erlotinib/farmacocinética , Radioisótopos de Gálio , Humanos , Neoplasias Pulmonares/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Estrutura Molecular , Neoplasias Cutâneas/metabolismo , Distribuição TecidualRESUMO
Somatostatin receptor positron emission tomography-computed tomography (PET/CT) with 68Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) peptides have become an indispensable part of disease assessment in patients with neuroendocrine tumors and forms the basis of personalized therapy with peptide receptor-based radionuclide therapy. With growing utilization of PET/CT in developing countries, availability of the indigenous GMP-certified 68Ge/68Ga generators is expected to further promote cost-effective molecular imaging service to the cancer patients. We present our initial clinical experience in 32 patients injected with 68Ga-DOTA-NOC prepared using 68Ga eluted from Bhabha Atomic Research Centre nanoceria-polyacrylonitrile sorbent-based 68Ge/68Ga generator and freeze-dried DOTA-NOC cold kits.
RESUMO
BACKGROUND & OBJECTIVES: Yttrium-90 ( 90 Y)-based radioembolization has been employed to treat hepatocellular carcinoma (HCC) as commercial radioactive glass and polymeric resin microspheres. However, in India and other Asian countries, these preparations must be imported and are expensive, validating the need for development of indigenous alternatives. This work was aimed to develop an economically and logistically favourable indigenous alternative to imported radioembolizing agents for HCC therapy. METHODS: The preparation of 90 Y-labelled Biorex 70 microspheres was optimized and in vitro stability was assessed. Hepatic tumour model was generated in Sprague-Dawley rats by orthotopic implantation of N1S1 rat HCC cell line. In vivo localization and retention of the 90 Y-labelled Biorex 70 microspheres was assessed for seven days, and impact on N1S1 tumour growth was studied by histological examination and biochemical assays. RESULTS: Under optimal conditions, >95% 90 Y-labelling yield of Biorex70 resin microspheres was obtained, and these showed excellent in vitro stability of labelling (>95%) at seven days. In animal studies, 90 Y-labelled Biorex 70 microspheres were retained (87.72±1.56% retained in liver at 7 days). Rats administered with 90 Y-labelled Biorex 70 microspheres exhibited lower tumour to liver weight ratio, reduced serum alpha-foetoprotein level and greater damage to tumour tissue as compared to controls. INTERPRETATION & CONCLUSIONS: 90 Y-labelled Biorex 70 microspheres showed stable retention in the liver and therapeutic effect on tumour tissue, indicating the potential for further study towards clinical use.
Assuntos
Carcinoma Hepatocelular/radioterapia , Neoplasias Hepáticas/radioterapia , Neoplasias Experimentais/radioterapia , Radioisótopos de Ítrio/uso terapêutico , Animais , Carcinoma Hepatocelular/patologia , Modelos Animais de Doenças , Embolização Terapêutica/métodos , Humanos , Índia , Fígado/patologia , Fígado/efeitos da radiação , Neoplasias Hepáticas/patologia , Microesferas , Neoplasias Experimentais/patologia , Ratos , Resultado do TratamentoRESUMO
Present work evaluates the potential of a newly synthesized (68)Ga-NOTA-folic acid conjugate for PET imaging of tumors over-expressing folate receptors (FRs). NOTA-folic acid conjugate was synthesized and characterized. It was radiolabeled with (68)Ga in ≥ 95% radiolabeling yields. In vitro cell binding studies showed a maximum cell uptake of 1.7±0.4% per million KB cells which was completely blocked on addition of cold folic acid showing specificity towards the FRs. However, further studies in tumor xenografts are warranted in order to assess the potential of (68)Ga-folic acid complex for imaging tumors over-expressing FRs.
Assuntos
Receptores de Folato com Âncoras de GPI/metabolismo , Ácido Fólico/farmacocinética , Radioisótopos de Gálio/uso terapêutico , Terapia de Alvo Molecular/métodos , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/radioterapia , Radioterapia/métodos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos da radiação , Radioisótopos de Gálio/química , Radioisótopos de Gálio/farmacocinética , Humanos , Marcação por Isótopo/métodos , Células KB , Neoplasias Experimentais/patologia , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Resultado do TratamentoRESUMO
This study aimed at the preparation and evaluation of (177)Lu-CHX-A''-DTPA-Bevacizumab for targeting VEGF over-expressing cancers. Bevacizumab conjugated to p-NCS-Bn-CHX-A''-DTPA was radiolabeled with (177)Lu. The radioimmunoconjugate characterized by SE-HPLC exhibited radiochemical purity of 98.0±0.6%. In vitro stability was retained upto 4 days at 37°C. In vitro cell binding studies showed good uptake by VEGF expressing U937 tumor cells. Biodistribution studies in melanoma model showed significant uptake and retention of (177)Lu-CHX-A''-DTPA-Bevacizumab in tumor with reduction in uptake in presence of cold Bevacizumab confirming its specificity to VEGF.
Assuntos
Bevacizumab/uso terapêutico , Lutécio/uso terapêutico , Ácido Pentético/análogos & derivados , Radioimunoterapia/métodos , Radioisótopos/uso terapêutico , Compostos Radiofarmacêuticos/uso terapêutico , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Animais , Bevacizumab/farmacocinética , Linhagem Celular Tumoral , Humanos , Imunoconjugados/isolamento & purificação , Imunoconjugados/farmacocinética , Imunoconjugados/uso terapêutico , Lutécio/farmacocinética , Melanoma Experimental/metabolismo , Melanoma Experimental/radioterapia , Camundongos , Camundongos Endogâmicos C57BL , Ácido Pentético/farmacocinética , Ácido Pentético/uso terapêutico , Radioisótopos/farmacocinética , Compostos Radiofarmacêuticos/isolamento & purificação , Compostos Radiofarmacêuticos/farmacocinética , Células U937 , Fator A de Crescimento do Endotélio Vascular/imunologiaRESUMO
BACKGROUND & OBJECTIVES: Radioimmunotherapy is extensively being used for the treatment of non-Hodgkin's lymphoma (NHL). Use of rituximab, a chimeric anti-CD20 antibody directed against the CD20 antigen in combination with suitable beta emitters is expected to result in good treatment response by its cross-fire and bystander effects. The present work involves the conjugation of p-isothiocyanatobenzyl DOTA (p-SCN-Bn-DOTA) to rituximab, its radiolabelling with [90] Y and in vitro and in vivo evaluation to determine its potential as a radioimmunotherapeutic agent. METHODS: Rituximab was conjugated with p-SCN-Bn-DOTA at 1:1 antibody: DOTA molar ratio. The number of DOTA molecules linked to one molecule of rituximab was determined by radioassay and spectroscopic assay. Radiolabelling of rituximab with 90 Y was carried out and its in vitro stability was evaluated. In vitro cell binding studies were carried out in Raji cells expressing CD20 antigen. Biodistribution studies were carried out in normal Swiss mice. RESULTS: Using both radioassay and spectroscopic method, it was determined that about five molecules of DOTA were linked to rituximab. Radiolabelling of the rituximab conjugate with [90] Y and subsequent purification on PD-10 column gave a product with radiochemical purity (RCP) > 98 per cent which was retained at > 90 per cent up to 72 h when stored at 37°C. In vitro cell binding experiments of 90 Y-DOTA-rituximab with Raji cells exhibited specific binding of 20.7 ± 0.1 per cent with [90] Y-DOTA-rituximab which reduced to 15.5 ± 0.2 per cent when incubated with cold rituximab. The equilibrium constant K d for 90 Y-DOTA-Rituximab was determined to be 3.38 nM. Radiolabelled antibody showed clearance via hepatobiliary and renal routes and activity in tibia was found to be quite low indicating in vivo stability of [90] Y-DOTA-rituximab. INTERPRETATION & CONCLUSIONS: p-SCN-Bn-DOTA was conjugated with rituximab and radiolabelling with 90 Y was carried out. In vitro studies carried out in Raji cells showed the specificity of the radiolabelled conjugate suggesting the potential uitability of the formulation as a radiopharmaceutical for therapy of NHL.
Assuntos
Linfoma não Hodgkin/tratamento farmacológico , Radioimunoterapia/métodos , Compostos Radiofarmacêuticos/administração & dosagem , Rituximab/administração & dosagem , Animais , Linhagem Celular Tumoral , Compostos Heterocíclicos/administração & dosagem , Compostos Heterocíclicos/química , Compostos Heterocíclicos/farmacocinética , Humanos , Linfoma não Hodgkin/imunologia , Linfoma não Hodgkin/patologia , Camundongos , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/química , Compostos Organometálicos/farmacocinética , Compostos Radiofarmacêuticos/química , Rituximab/química , Rituximab/farmacocinética , Distribuição Tecidual , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Preliminary work with (99m)Tc carbonyl-DTPA-Rituximab was attempted to test its feasibility as a sentinel lymph node (SLN) tracer for patients with breast cancer. (99m)Tc labeling of DTPA-Rituximab conjugate was carried out via (99m)Tc carbonyl synthon which exhibited >95% radiochemical purity and good in vitro stability. In vitro studies of (99m)Tc carbonyl-DTPA-Rituximab in normal and malignant B cells showed higher binding in malignant cells. In vivo distribution of (99m)Tc carbonyl-DTPA-Rituximab in Wistar rat footpad model indicated good retention by B-cells present in the sentinel lymph node.
Assuntos
Anticorpos Monoclonais Murinos , Linfonodos/diagnóstico por imagem , Metástase Linfática/diagnóstico por imagem , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Animais , Anticorpos Monoclonais Murinos/farmacocinética , Linfócitos B/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Linhagem Celular Tumoral , Estudos de Viabilidade , Feminino , Humanos , Técnicas In Vitro , Compostos de Organotecnécio/farmacocinética , Cintilografia , Compostos Radiofarmacêuticos/farmacocinética , Ratos , Ratos Wistar , Rituximab , Biópsia de Linfonodo SentinelaRESUMO
INTRODUCTION: Radioimmunotherapy is a feasible treatment modality for B-cell lymphomas expressing CD20 antigen. Tagging of anti-CD20 monoclonal antibody with a ß(-) emitter will deliver radiation to the tumor preferentially, thereby causing its destruction. This work explores the utility of (177)Lu-CHX-A"-DTPA-Rituximab as a radioimmunotherapeutic agent for non-Hodgkin's lymphoma (NHL). METHODS: Rituximab was conjugated with p-NCS-Bn-CHX-A"-DTPA and radiolabeled with (177)Lu. (177)Lu-CHX-A"-DTPA-Rituximab was characterized by SE-HPLC. In vitro cell binding and inhibition studies were carried out in Raji cells which express CD20 antigen. Biodistribution studies were performed in SCID mice bearing lymphoma at various time intervals. RESULTS: The CHX-A"-DTPA-Rituximab conjugate prepared had three molecules of DTPA per Rituximab molecule. Radiochemical purity of (177)Lu-CHX-A"-DTPA-Rituximab was >95%. In the HPLC system, (177)Lu-CHX-A"-DTPA-Rituximab showed a single peak (Rt â¼15.5 minutes). In vitro cell binding studies showed 38.9%±1.1% binding of (177)Lu-CHX-A"-DTPA-Rituximab (â¼6.7 nM of radioimmunoconjugate) with Raji cells which reduced to 17.7%±0.5% with the addition of 67 nM of cold antibody. Biodistribution studies showed good tumor uptake at all the time points studied. CONCLUSIONS: In vitro and in vivo studies showed good specificity of (177)Lu-CHX-A"-DTPA-Rituximab toward CD20 antigen. It can be concluded that (177)Lu-CHX-A"-DTPA-Rituximab could be a promising agent in the treatment of NHL.
Assuntos
Linfoma não Hodgkin/tratamento farmacológico , Linfoma não Hodgkin/radioterapia , Radioimunoterapia/métodos , Rituximab/uso terapêutico , Animais , Humanos , Camundongos , Rituximab/administração & dosagem , Rituximab/farmacologiaRESUMO
OBJECTIVE: In-situ sentinel lymph node (SLN) detection is an important component in staging cancers of various origins. At present, technetium-99m (Tc)-labeled nanoparticle formulations like sulfur colloid and human serum albumin (HSA) nanocolloid are used in the clinic as SLN tracers. In India, HSA nanocolloid cold kits have so far been imported. This study aims to develop and evaluate an indigenous alternative to imported HSA nanocolloid cold kits for SLN detection/imaging. MATERIALS AND METHODS: Production of cold kits was standardized and the product was characterized for its suitability in terms of particle size. Tc-labeling of an in-house HSA nanocolloid was optimized, and the yield and stability of the product were assessed. Animal studies were performed in Wistar rats using the footpad model. Clinical evaluation was performed in 54 patients using a combination of scintigraphic imaging and a hand-held gamma probe. RESULTS AND CONCLUSION: With the optimized protocol, HSA nanocolloids with particle sizes ranging from 50 to 200 nm were obtained. Greater than 90% Tc-labeling yield was obtained in 15 min reactions, and the radiopharmaceutical was stable for up to 24 h after preparation. The animal studies showed similar SLN uptake and improved retention pattern compared with those of the imported Nanocoll radiopharmaceutical. Clinical studies showed detectable 'hot' nodes in 53 of 54 patients, demonstrating sensitivity of the product for clinical utility. In conclusion, this indigenous HSA nanocolloid cold kit is proposed as a logistically favorable alternative to imported kits for SLN detection in the Indian clinical scenario.