RESUMO
Bleeding can be a serious complication of surgery, and topical thrombin is widely used as an adjunct to hemostasis in diverse surgical settings. The potent hemostatic properties of thrombin derive from its ability to activate platelets directly to aggregate and adhere to damaged vessels and to catalyze the formation simultaneously of a fibrin matrix. Application of exogenous thrombin bypasses the physiological process of generating a thrombin burst by directly initiating the terminal reactions of blood clot formation. Currently, thrombin used to control surgical bleeding is primarily from bovine plasma, with a small percentage from human plasma. Human thrombin isolated from pooled plasma carries the risk of transmitting plasma-borne pathogens or prion diseases. The bovine preparations have been associated with protein and preparative contaminants that pose potential risks of developing cross-reacting antibodies. There is a need for a pure therapeutic preparation of human thrombin. Recombinant human thrombin (rhThrombin) has been efficiently produced from a prethrombin-1 precursor obtained from Chinese hamster ovary cell culture. This rhThrombin is substantially free of process-derived contaminants and has been characterized extensively in terms of composition, primary, secondary, and tertiary structure, enzymatic activity; and in vivo pharmacology. In vivo studies of topically applied rhThrombin have shown it is effective in achieving hemostasis in a rabbit liver excisional wound model. Clinical studies are ongoing to evaluate the safety and efficacy of rhThrombin as an adjunct to hemostasis in patients undergoing surgery.
Assuntos
Trombina/química , Trombina/uso terapêutico , Animais , Perda Sanguínea Cirúrgica/prevenção & controle , Humanos , Peso Molecular , Controle de Qualidade , Proteínas Recombinantes , Trombina/genética , Trombina/isolamento & purificaçãoRESUMO
PURPOSE: This study examined a pretarget radioimmunotherapy strategy for treatment of an i.p. tumor model (LS174T). EXPERIMENTAL DESIGN: The strategy used regional administration (i.p.) of a novel targeting molecule composed of four CC49 anti-tumor-associated glycoprotein 72 (TAG-72) single-chain antibodies linked to streptavidin as a fusion protein (CC49 fusion protein); 24 hours later, a synthetic clearing agent was administered i.v. to produce hepatic clearance of unbound CC49 fusion protein/synthetic clearing agent complexes. Four hours later, a low molecular weight radiolabeled reagent composed of biotin conjugated to the chelating agent 7,10-tetra-azacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) complexed with (111)In-, (90)Y-, or (177)Lu-DOTA-biotin was injected. RESULTS: Radiolocalization to tumor sites was superior with i.p. administration of radiolabeled DOTA-biotin as compared with i.v. administration. Imaging and biodistribution studies showed excellent tumor localization of radioactivity with (111)In- or (177)Lu-DOTA-biotin. Tumor localization of (111)In-DOTA-biotin was 43% ID/g and 44% ID/g at 4 and 24 hours with the highest normal tissue localization in the kidney with 6% ID/g at 48 and 72 hours. Therapy studies with (90)Y-DOTA-biotin at doses of 400 to 600 microCi or (177)Lu-DOTA-biotin at doses of 600 to 800 microCi produced significant prolongation of survival compared with controls (P = 0.03 and P < 0.01). CONCLUSIONS: Pretarget radioimmunotherapy using regional administration of CC49 fusion protein and i.p. (90)Y- or (177)Lu-DOTA-biotin represents a successful therapeutic strategy in the LS174T i.p. tumor model and this strategy may be applicable to human trials in patients with i.p. ovarian cancer.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Anticorpos Antineoplásicos/administração & dosagem , Neoplasias do Colo/radioterapia , Radioimunoterapia/métodos , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/farmacocinética , Anticorpos Antineoplásicos/química , Antígenos de Neoplasias/imunologia , Biotina/administração & dosagem , Biotina/análogos & derivados , Biotina/química , Biotina/farmacocinética , Linhagem Celular Tumoral , Neoplasias do Colo/patologia , Glicoproteínas/imunologia , Humanos , Radioisótopos de Índio , Injeções Intraperitoneais , Radioisótopos do Iodo , Lutécio , Camundongos , Camundongos Nus , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/química , Compostos Organometálicos/farmacocinética , Radioisótopos , Estreptavidina/administração & dosagem , Estreptavidina/química , Estreptavidina/farmacocinética , Análise de Sobrevida , Fatores de Tempo , Distribuição Tecidual , Resultado do Tratamento , Ensaios Antitumorais Modelo de Xenoenxerto/métodos , Radioisótopos de ÍtrioRESUMO
The radiolanthanides (149)Pm, (166)Ho, and (177)Lu possess a range of half-lives and alpha(-) beta(-) energies for targeted radiotherapy of cancer. (149)Pm-, (166)Ho-, and (177)Lu-DOTA-biotin were pretargeted to LS174T colorectal tumors in nude mice with CC49 scFvSA antibody-streptavidin fusion protein. Tumor uptakes of (149)Pm (22.9% ID/g), (166)Ho (30.2% ID/g), and (177)Lu (35.4% ID/g) peaked at 1-4 h. Rapid blood disappearance was accompanied by urinary excretion of 59-66% ID within 1 h. Biodistributions of these agents show promise for pretargeted radioimmunotherapy of cancer.
Assuntos
Anticorpos Antineoplásicos/metabolismo , Biotina/análogos & derivados , Biotina/farmacocinética , Neoplasias do Colo/metabolismo , Sistemas de Liberação de Medicamentos/métodos , Compostos Organometálicos/farmacocinética , Radioimunoterapia/métodos , Radioisótopos/farmacocinética , Estreptavidina/farmacocinética , Animais , Anticorpos Antineoplásicos/administração & dosagem , Biotina/administração & dosagem , Linhagem Celular Tumoral , Neoplasias do Colo/radioterapia , Hólmio/administração & dosagem , Hólmio/farmacocinética , Humanos , Fragmentos de Imunoglobulinas/administração & dosagem , Fragmentos de Imunoglobulinas/metabolismo , Injeções Intravenosas , Lutécio/administração & dosagem , Lutécio/farmacocinética , Taxa de Depuração Metabólica , Camundongos , Camundongos Nus , Especificidade de Órgãos , Compostos Organometálicos/administração & dosagem , Promécio/administração & dosagem , Promécio/farmacocinética , Radioisótopos/administração & dosagem , Compostos Radiofarmacêuticos/administração & dosagem , Compostos Radiofarmacêuticos/farmacocinética , Proteínas Recombinantes de Fusão/administração & dosagem , Proteínas Recombinantes de Fusão/farmacocinética , Estreptavidina/administração & dosagem , Distribuição TecidualRESUMO
Pretarget radioimmunotherapy (RIT) is a multistep strategy for cancer therapy designed to reduce nontarget organ exposure by uncoupling the tumor targeting moiety from the radioactive ligand. Using this approach, we and others have demonstrated objective responses to therapy among patients with non-Hodgkin's lymphoma, with less hematological toxicity than is typically seen at equivalent doses of conventional RIT in the same patient population. In the present study, we show that combination therapy with gemcitabine (200 mg/kg on days -1 and +1) and Pretarget RIT (400 micro Ci (90)Y-labeled DOTA-biotin on day +1) is superior to Pretarget monotherapy (400 or 800 micro Ci (90)Y) as well as to gemcitabine monotherapy in nude mice bearing established human LS174T colon cancer xenografts. For the targeting moiety, we used a murine anti-TAG-72 (CC49) single-chain Fv-streptavidin (scFvSA) fusion protein that has been shown to be safe and well-tolerated in humans. The median number of days to tumor volume doubling in the gemcitabine-only studies (200 mg/kg) was 10.4 +/- 5.5 days; in the Pretarget 400 micro Ci dose-only studies, tumor doubling time was 6.7 +/- 4.9 days; and in combination therapy studies, it was 23.9 +/- 7.2 days (P = 0.0001 versus Pretarget or gemcitabine monotherapy). There were no consistently significant differences among the two monotherapy regimens and the combination therapy regimen with respect to peripheral blood cell counts, nor were there significant differences in bone marrow colony-forming activity among the three treatment groups. These data indicate that gemcitabine can be combined with Pretarget RIT to increase antitumor response, without increasing hematological toxicity, in a murine xenograft model.
Assuntos
Anticorpos Antineoplásicos/uso terapêutico , Antimetabólitos Antineoplásicos/uso terapêutico , Neoplasias do Colo/terapia , Desoxicitidina/análogos & derivados , Desoxicitidina/uso terapêutico , Radioimunoterapia/métodos , Animais , Bromodesoxiuridina/farmacologia , Ciclo Celular , Feminino , Humanos , Ligantes , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Genéticos , Transplante de Neoplasias , Proteínas Recombinantes de Fusão/metabolismo , Fatores de Tempo , Distribuição Tecidual , GencitabinaRESUMO
Although radioimmunotherapy with radiolabeled intact monoclonal antibodies has demonstrated efficacy in the treatment of lymphoma, it provides low tumor-to-normal-tissue radionuclide target ratios and unwanted prolonged radiation exposure to the bone marrow. To overcome these obstacles, the administration of the radionuclide was separated from that of the antibody by using an anti-IL-2 receptor alpha antibody single chain Fv-streptavidin fusion protein, followed by radiolabeled biotin to treat lymphoma or leukemia xenografted mice. This Pretarget approach provided extremely rapid and effective tumor targeting, permitting the use of short-lived alpha-emitting radionuclides. With the beta-emitter (90)Y, all of the 10 lymphoma-xenografted mice were cured. With the alpha-emitter (213)Bi, significant efficacy was obtained in treating leukemic mice, and, furthermore, when combined with immunotherapy, 7 of 10 leukemic mice were cured. Thus, Pretarget radioimmunotherapy is very promising and could represent the next generation in the treatment of lymphoma and leukemia.