No abstract available.
Brain Neoplasms* ; Brain* ; Cell Line* ; Immunotoxins*

Gastric cancer cells express large amounts of galectin-3 on the cell surface. This fact may provide the possibility to use galectin-3 protein as a surface target for delivering cytotoxic anticancer agents. To investigate the possibility of application of galectin-3 protein as a target protein in delivering cytotoxic anticancer agents, we synthesized doxorubicin immunoconjugate by using maleimidocaproic acid and conjugated doxorubicin immunoconjugate to anti-galectin-3 mAb. The anticancer effect of immunotoxin was assayed on NIH3T3, AGS and KATO III cell lines. The anticancer effect of immunotoxin on AGS cell line is highest and that of KATO III is higher than that of NIH3T3. This results relate to that of flow cytometry analysis previously shown and indicate that galectin-3 protein can be used as a target protein on the surface of gastric cancer cell for delivering cytotoxic anticancer agents.
Antineoplastic Agents* ; Cell Line ; Doxorubicin ; Flow Cytometry ; Galectin 3 ; Galectins* ; Immunoconjugates ; Immunotoxins ; Staphylococcal Protein A ; Stomach Neoplasms

The adoption of oligonucleotide aptamer is well on the rise, serving an ever increasing demand for versatility in biomedical field. Through the SELEX (Systematic Evolution of Ligands by EXponential enrichment), aptamer that can bind to specific target with high affinity and specificity can be obtained. Aptamers are single-stranded nucleic acid molecules that can fold into complex threedimensional structures, forming binding pockets and clefts for the specific recognition and tight binding of any given molecular target. Recently, aptamers have attracted much attention because they not only have all of the advantages of antibodies, but also have unique merits such as thermal stability, ease of synthesis, reversibility, and little immunogenicity. The advent of novel technologies is revolutionizing aptamer applications. Aptamers can be easily modified by various chemical reactions to introduce functional groups and/or nucleotide extensions. They can also be conjugated to therapeutic molecules such as drugs, drug containing carriers, toxins, or photosensitizers. Here, we discuss new SELEX strategies and stabilization methods as well as applications in drug delivery and molecular imaging.
Antibodies ; Drug Delivery Systems ; Immunotoxins ; Ligands ; Methods* ; Molecular Imaging ; Photosensitizing Agents ; Sensitivity and Specificity

Traditional chemotherapy has become one of the essential treatments of cancer. However, cytotoxic agents are not tumor specific, which would cause serious side effects. Antibody-drug conjugates (ADCs), also called immunoconjugates, belong to the "targeted chemotherapeutics" category of anti-cancer drugs. ADCs are composed of three components including the cytotoxic drug, the monoclonal antibody, and the linker connecting the drug to the antibody. With the special-binding between antibody and antigen expressed on the surface of targeted cancer cells, ADCs provide a method to achieve excellent localization of the drug at the desired site in the body. The internalization and formation of ADCs are crucial in designing and applying an antibody conjugate to a particular disease model. In this review, we summarize three distinct internalization routes of ADCs and analysis the structure of ADCs. We also discuss in detail the categories and interaction of every component, as well as their influence to targeting property, liability and activity.
Antibodies, Monoclonal ; administration & dosage ; Antineoplastic Agents ; administration & dosage ; Drug Delivery Systems ; Immunotoxins ; chemistry ; therapeutic use

A murime monoclonal antibody (mAb) specific for the envelope glycoprotein gp120 of human immunodeficiency virus type-I (HIV-1) was chemically coupled to pokeweed antiviral protein (PAP) from Phytolacca americana. The immunotoxin was purified by FPLC using 5200 colum. The purified immunotoxin efficiently bound to HIV-infected T cells as evidenced by fluorescence-activated cell sorter analysis. The immunotoxin selectively killed human T lymphoid lines infected with HIV-lIIIB at less than 250 pM of the immunotoxin cells, while PAP or mAb alone did not have any significant effect on infected cells. The uninfected control T cell lines were not affected. Human cells infected with HIV-2 or other HIV-1 strains were not killed, suggesting that the killing depends completely on the antibody used for coupling. These in vitro results suggest that the PAP-mAb conjugate may be used to selectively remove cells expressing viral antigens from individuals infected with HIV.
Antigens, Viral ; Cell Line ; Glycoproteins ; HIV ; HIV-1 ; HIV-2 ; Homicide ; Humans* ; Immunotoxins ; Phytolacca americana* ; T-Lymphocytes*

OBJECTIVE: Because of the limited penetration into the central nervous system after systemic administration of numerous therapeutic compounds, intratumoral chemotherapy for brain tumors has also been used. However, the efficacy of intratumoral drug administration is restricted by the poor diffusion of drug through tumor and brain interstitium. In order to enhance the diffusion of chemotherapeutic agent and increase the cytotoxicity with minimal dose, the authors report the results of convection-enhanced delivery(CED) of chemotherapeutic agent to the malignant brain tumor as a method of enhancing cerebral drug delivery. METHODS: Authors used "CADD-Micro(R) ambulatory infusion pump" from Deltec, which can be programmed for continuous infusion. Intratumoral injection of chemotherapeutic drug using the pump was applied to eight patients with glioma and one patient with lymphoma. Surgery was done and tumor was removed as much as possible. The tip of catheter was placed in the center of tumor cavity. Adriamycin (0.16~0.32mg) was put in the reservoir which was connected to the proximal catheter and fixed in the pump device. Twenty-four hours after surgery, Adriamycin was infused. RESULTS: There was no adverse reaction of CED technique. Compared with current delivery techniques, the improvement of survival rate has been observed(5 patients: alive, 3 patients: dead, 1 patient: lost(alive to 5 mo.)). CONCLUSION: CED can be useful method for distributing therapeutic molecules in the interstitial space of tumor and can be utilized for chemotherapeutic agents, immunotoxins, and gene etc..
Brain ; Brain Neoplasms ; Catheters ; Central Nervous System ; Diffusion ; Doxorubicin ; Drug Therapy ; Glioma ; Humans ; Immunotoxins ; Lymphoma ; Survival Rate

OBJECTIVE: Immunotoxin therapy is a novel approach for the treatment of tumor, and it has been successfully used in the central nervous system. The purpose of this study is to evaluate the cytotoxicity of OKT9 ScFv-Diphtheria toxin fusion immunotoxin on various human brain tumor cell lines. METHODS: Immunotoxin which was composed of OKT9 ScFv and Diphtheria toxin was made. Its cytotoxicity on glioblastoma cell lines(U87MG, U118MG) and medulloblastoma cell line(TE671) was tested and compared with anti-cancer chemotherapeutic agents. And we also examined the relationship between its cytotoxicity and transferrin receptor expression. RESULTS: It showed most cytotoxicity on U87MG cell line and nearly no effect on U118MG cell line, moderate cytotoxicity on TE671 cell line in sixteen hours exposure experiment. In continuous exposure experiment, it showed moderate cytotoxicity on U118MG cell line, but showed strong cytotoxicity on other cell lines comparable or higher than anti-cancer chemotherapeutic agents. The relationship between its cytotoxicity and transferrin receptor expression was tested using flow cytometry, but no direct relationship could be found. CONCLUSION: Collectively, the result shows the cytotoxic effects of OKT9 ScFv-Diphtheria toxin fusion immunotoxin against various human brain tumor cell lines in continuous exposure experiment. Therefore, we suggest that this immunotoxin could be developed as a potential immunotherapeutic agent in the treatment of various human brain tumor clinically.
Brain Neoplasms* ; Brain* ; Cell Line* ; Central Nervous System ; Diphtheria Toxin ; Flow Cytometry ; Glioblastoma ; Humans* ; Immunotoxins* ; Medulloblastoma ; Receptors, Transferrin

PURPOSE: To obtain basic data for development of a glioblastoma-specific immunotoxin, the expression of variable cell surface receptors on a human glioblastoma xenograft model was evaluated, using NOD/SCID mice. MATERIALS AND METHODS: We developed a xenograft model in NOD/SCID mice implanted with a human glioblastoma cell line (U-87MG). Immunohistochemical studies were performed on implanted tumor nodules (n=8) using antibodies against CD71, EGFR, IGF-IRalpha, CXCR4 and IL-4Ralpha. RESULTS: Expression of IL-4Ralpha, in implanted tumornodules, was the highest of the cell surface receptors evaluated in this study. However, the endothelial cells in, and around, the tumor nodules also revealed immunopositivity against IL-4Ralpha. The immunoreactivity of IL-4Ralpha, and other surface receptors such as CD71, IGF-IRalpha and EGFR, was prominent in tumor nodules associated with tumor necrosis. CONCLUSION: IL-4Ralpha would be a possible target for the development of glioblastoma-specific immunotoxin, although there are limitations due to its endothelial expression.
Animals ; Antibodies ; Cell Line ; Endothelial Cells ; Glioblastoma* ; Heterografts* ; Humans* ; Immunotoxins ; Mice* ; Mice, SCID ; Necrosis ; Receptors, Cell Surface*

Monoclonal antibody-targeted therapy has been a hot spot in current clinical cancer treatment. As current antibody drugs have large molecule sizes leading to poor tissue penetration, and high dosage in clinical application leading to high cost, to overcome the problems, the development of new antibody drugs with miniaturization and high potency has become a new trend. In recent years, the conjugates of monoclonal antibodies and cytotoxins, called antibody-drug conjugates (ADCs), have entered the arsenal of anti-cancer drugs, becoming a new format of antibody drugs and attracting extensive attentions. The ADC molecule usually consists of antibody, linker and effector molecule. According to different effector molecules, ADCs can be divided into three categories as chemo-conjugates, immunotoxins and radio-conjugates. When ADC molecules are internalized into cancer cells, cytotoxins will be released by chemical, enzyme degradation or by action of lysosomal proteases, then kill targeted cells by inhibiting protein synthesis, depolymerizing microtubules or breaking double-strand DNA. Recently, two ADC drugs have been approved by the US FDA and more ADC drug candidates are in clinical phase II or III trials which show significantly clinical effects and attracting much attention and competition of pharmaceutical enterprises. In this review, antibody conjugates in the past and present will be summarized and the future development trends and challenges of this type of antibody drugs will be discussed.
Antigens, CD ; metabolism ; Hematologic Neoplasms ; metabolism ; therapy ; Humans ; Immunoconjugates ; chemistry ; therapeutic use ; Immunotherapy ; methods ; Immunotoxins ; chemistry ; therapeutic use ; Radioimmunotherapy ; methods

OBJECTIVEMonoclonal antibody (mAb) conjugated with certain toxin to generate immunotoxin bears an important and promising effect as a new therapy for patients with hematopoietic malignancies. However, most toxic moieties conjugated with antibody proteins reported in the literature were toxic proteins which presented immunogenicity to patients capable of inducing anti-toxin antibody. Norcantharidin (NCTD) is a small molecule toxin. It does not have the immunogenicity to human body so that it bears a promising potential for development of new targeting drug. In this study, a new clone of self-made anti-CD19 mAb named ZCH-4-2E8 conjugated with NCTD was used to investigate its targeting efficacy against CD19+ lymphoid malignant Nalm-6 cells in vitro to provide the experimental data for the further development of this new targeting agent.

METHODSA monoclonal antibody named 2E8 was prepared from mouse ascites and purified by gel chromatography. The purity of the antibody protein was checked by SDS-PAGE assay. Immunotoxin 2E8-NCTD was successfully generated through conjugating CD19 mAb protein and Norcantharidin by the activated ester method. The binding activity of the immunoconjugate (2E8-NCTD) against CD19 antigens on cell surface and the expression levels of CD19 antigens on Nalm-6 and K562 cells were examined by flow cytometry. Comparisons of the inhibitory effects among PBS, purified 2E8 antibody, norcantharidin and immunotoxin 2E8-NCTD groups on cell growth of either Nalm-6 cells or K562 cells were made.

RESULTSThe purity of the purified 2E8 antibody was higher than 99.00% demonstrated by SDS-PAGE assay. 2E8 antibody in the supernatant reacted with 99.34% of Nalm-6 cells, while only 0.98% of K562 cells reacted with this antibody. The newly generated immunotoxin (2E8-NCTD) had a positive rate of 99.90% on Nalm-6 cells with little reduction of binding activity. From the in vitro study, both 2E8-NCTD and norcantharidin were shown to have significant inhibitory effects on the growth of CD19+ Nalm-6 cells (P < 0.001), while the purified 2E8 antibody did not show any significant influences on the growth of Nalm-6 cells. Since no significant inhibitory effects were identified among immunotoxin 2E8-NCTD, 2E8 antibody and control groups on CD19(-) K562 cells, a significant targeting effect of the 2E8-NCTD against Nalm-6 cells was confirmed.

CONCLUSIONSThe immunotoxin 2E8-NCTD was successfully synthesized by activated ester method with an excellent targeting killing effect on CD19+ Nalm-6 leukemia cells in vitro, which provides some experimental data for the further development of this new targeting agent.

Animals ; Antibodies, Monoclonal ; biosynthesis ; Antigens, CD19 ; immunology ; Bridged Bicyclo Compounds, Heterocyclic ; chemical synthesis ; immunology ; Electrophoresis, Polyacrylamide Gel ; Humans ; Hybridomas ; Immunotoxins ; immunology ; K562 Cells ; Mice ; Mice, Inbred BALB C