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

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

OBJECTIVESTo obtain high therapeutic effect and low toxicity single-chain immunotoxin against hepatocellular carcinoma (HCC).

METHODSHuman mutant tumor necrosis factor-alpha (mTNFalpha) was linked with the 3' end of humanized single-chain Fv against HCC (hscFv25) in pGEX4T-1 vector. The anti-HCC immunotoxin was expressed in Escherichia coli and identified by western blot. The primary tumor regression trial in nude mice bearing HCC was evaluated the targeting therapeutic value of hscFv25-mTNFalpha. The tumor tissues were stained by immunohistochemical with TNFalpha antibody.

RESULTSThe expression of single-chain immunotoxin hscFv25-mTNFalpha was 12% of total bacteria proteins. The tumor regression trials of hscFv25-mTNFalpha showed 5/5 effective. It had 2/5 completely remission and 3/5 partly remission. The therapeutic result of hscFv25-mTNFalpha was better than that of mTNFalpha (F=8.70, 0.05). The HCC tissue treated by hscFv25-mTNFalpha expressed TNFalpha positive reaction. The positive granule mainly existed in HCC cytoplasm.

CONCLUSIONThe single-chain immunotoxin hscFv25-mTNFalpha has high therapeutic effect and low toxicity. It has potentialities for clinical application.

Animals ; Immunoglobulin Fragments ; therapeutic use ; Immunohistochemistry ; Immunotoxins ; therapeutic use ; Liver Neoplasms, Experimental ; therapy ; Mice ; Mice, Inbred BALB C ; Tumor Necrosis Factor-alpha ; therapeutic use

Human epidermal growth factor receptor 2 (HER2) belongs to the transmembrane glycoprotein receptor family. Overexpression of HER2 could directly lead to tumorigenesis and metastasis. This phenomenon could be observed in the breast cancer, ovarian cancer, gastric cancer, lung cancer and prostate cancer. Compared with the conventional chemotherapy, the targeted treatment of antibody is more specific and has lower side effects. This review describes the current status of monotherapy and combination therapies of anti-HER2 antibodies, trastuzumab and pertuzumab, with chemotherapeutic drugs. The development trends of new formats of anti-HER2 antibody drugs such as bispecific antibody, immunotoxin are also discussed.
Antibodies, Monoclonal, Humanized ; therapeutic use ; Antineoplastic Agents ; therapeutic use ; Drug Delivery Systems ; Humans ; Immunoconjugates ; therapeutic use ; Immunotoxins ; therapeutic use ; Neoplasms ; metabolism ; therapy ; Receptor, ErbB-2 ; antagonists & inhibitors ; metabolism ; Trastuzumab

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune disease of the central nervous system (CNS); it serves as a model for the human multiple sclerosis (MS). In mice, EAE is mediated by T cells specific for various myelin basic proteins which migrate from the periphery to the CNS. In search of a way to prevent the induction and progression of EAE, we observed the effects of recombinant immunotoxin IP10-DT390 on blocking or eliminating the active T cells in the EAE model. In this paper is presented an experimental gene therapy-based model in which the mice were made resistant to EAE induction by plasmid DNA encoding recombinant immunotoxin that was injected into the leg muscles of mice. The new immuno-biological construct could selectively impair autoreactive T-cell homing while the duration of clinical signs is shorter, and the new construct would not affect other components of the immune response. These data demonstrated the effectiveness of the constructs in the treatment of EAE and suggested its usefulness in the treatment of other autoimmune diseases.
Animals ; Chemokine CXCL10 ; biosynthesis ; genetics ; therapeutic use ; Diphtheria Toxin ; biosynthesis ; genetics ; therapeutic use ; Encephalomyelitis, Autoimmune, Experimental ; immunology ; pathology ; therapy ; Female ; Genetic Therapy ; Immunoglobulin Fragments ; biosynthesis ; genetics ; therapeutic use ; Immunotoxins ; genetics ; metabolism ; therapeutic use ; Mice ; Mice, Inbred C57BL ; Receptors, CXCR3 ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; therapeutic use ; Recombinant Proteins ; biosynthesis ; genetics ; therapeutic use ; T-Lymphocytes ; immunology ; Transfection

OBJECTIVETo evaluate the anti-tumor effect of recombinant toxin EGF-TCS against transplanted human hepatocellular carcinoma in nude mice.

METHODSHuman hepatocellular carcinoma BEL-7,402 cells were inoculated subcutaneously in the right axillary region of nude mice, and 6 days later, EGF-TCS was injected intravenously at 100, 50, and 25 microg/kg. The mice were executed on the next day of drug withdrawal and the tumors were weighed and the tumor inhibition rate calculated. Immunohistochemistry was also performed on the tumor tissues to provide clue for the possible pathways of tumor inhibition.

RESULTSEGF-TCS markedly inhibited the tumor growth in nude mice, with a tumor inhibition rate of 71.3%, 60.87% and 45.22% corresponding to EGF-TCS dosage of 100, 50, and 25 microg/kg, respectively. Variance analysis suggested that EGF-Linker-TCS could significantly inhibit the tumor growth in the mice (F=8.712, P=0.006), and immunohistochemistry showed significantly inhibited angiogenesis in the tumors by EGF-TCS. No blood vessels were found in the tumor tissues in high dosage group, and there were also reduced blood vessels in the other two smaller dose groups in comparison with the untreated model group, indicating that EGF-TCS inhibited tumor growth and migration by inhibiting tumor angiogenesis.

CONCLUSIONEGF-TCS can inhibit the growth of solid tumors in nude mice, suggesting the potential value of this preparation in cancer therapy.

Animals ; Antineoplastic Agents ; metabolism ; therapeutic use ; Carcinoma, Hepatocellular ; drug therapy ; Cell Line, Tumor ; Disease Models, Animal ; Epidermal Growth Factor ; Female ; Humans ; Immunotoxins ; genetics ; metabolism ; therapeutic use ; Liver Neoplasms ; drug therapy ; Male ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Random Allocation ; Recombinant Fusion Proteins ; genetics ; metabolism ; therapeutic use ; Trichosanthin ; genetics ; metabolism ; therapeutic use

Eight saporin peaks were obtained from the purification of seed extracts of Saponaria officinalis L. Saporin peak No. 6 (SAP-6) showed the highest activity in the inhibition of protein synthesis (98%) in an in vitro translation study. An immunotoxin (IT) was prepared from SAP-6 conjugated to a monoclonal anti-CEA antibody 26/5/1 (mab B) using N-succinimidyl pyridyl dithiopropionate (SPDP) and 2-iminothiolane as a cross linker. Under thermal stability study by a DSC (differential scanning calorimetry), the IT showed a denature temperature of 75 degrees C. In in vitro translation studies, the purified IT showed the same activity as SAP-6 at 10(-7) M and 10(-9) M protein concentration at 0, 30 and 60-min incubation effects with mab B and SAP-6 not conjugated at 24-hr incubation periods on human promyelocytic cell line HL 60 and on human colon adenocarcinoma cell lines which were SW 403, LoVo and LS 174 T. SAP-6, mab B and IT had no cytotoxic effect on HL-60. The IT showed a higher cytotoxic effect than SAP-6 in CEA-positive cell lines. The IT demonstrated the highest cytotoxic effect of 51% inhibition of control at 10(-7) M on the LS 174 T.
Antibodies, Monoclonal/*therapeutic use ; Antineoplastic Agents, Phytogenic/administration & dosage/*pharmacology ; Carcinoembryonic Antigen/biosynthesis/*immunology ; Colonic Neoplasms/*pathology/therapy ; Hot Temperature ; Humans ; Immunotoxins/*therapeutic use ; *N-Glycosyl Hydrolases ; Plant Proteins/administration & dosage/*pharmacology ; Ribosome Inactivating Proteins, Type 1 ; Tumor Cells, Cultured/drug effects

OBJECTIVETo evaluate the therapeutic effect of a new recombinant immunotoxin mMIP-1alpha-DT390 on experimental autoimmune encephalomyelitis (EAE).

METHODSEAE was induced in the low-sensitive strain C57BL/6 mice with intraperitoneal injection of myelin basic protein (MBP) to simulate the human disease multiple sclerosis, followed by intramuscular injection of cationic liposome carrying the plasmid DNA SRalpha-mMIP-1alpha-DT390 in the leg muscle to elicit resistance to EAE development. The mice were then examined daily for clinical signs of EAE by an observer blind to the treatment protocol. For immunohistochemistry the mice were anesthetized and perfused with sterile PBS and paraformaldehyde, and the cerebrum, cerebellum, medulla and spinal cord were removed for preparation of serial sections. The mononuclear cells (MNCs) from the EAE mouse spleens were prepared for three-color flow cytometry analysis of the surface markers with appropriate antibodies following the BD Pharmingen cytokine staining protocol.

RESULTSEAE model was successfully established by active MBP immunization in C57BL/6 mice. Administration of the immunotoxin mMIP-1alpha-DT390 significantly delayed the disease onset and lowered the mean clinical score for EAE as compared with the control mice. Immunohistochemistry demonstrated much less CCR5(+) infiltrating cells in the central nervous system in mMIP-1alpha-DT390-treated mice than in the control. The treatment also eliminated reactive T cells in the periphery blood without affecting the number of B cells.

CONCLUSIONThe immunotoxin mMIP-1alpha-DT390 can attenuate the disease activity of EAE in mice, suggesting its potential use in the treatment of other autoimmune disorders.

Animals ; Antigens, CD19 ; analysis ; B-Lymphocytes ; cytology ; metabolism ; CD3 Complex ; analysis ; Chemokine CCL3 ; genetics ; metabolism ; Diphtheria Toxin ; genetics ; metabolism ; Disease Models, Animal ; Encephalomyelitis, Autoimmune, Experimental ; drug therapy ; Female ; Flow Cytometry ; Immunoglobulin Fragments ; genetics ; metabolism ; Immunohistochemistry ; Immunologic Factors ; therapeutic use ; Immunotoxins ; therapeutic use ; Meninges ; chemistry ; pathology ; Mice ; Mice, Inbred C57BL ; Multiple Sclerosis ; drug therapy ; NIH 3T3 Cells ; Receptors, CCR5 ; analysis ; Recombinant Fusion Proteins ; genetics ; metabolism ; therapeutic use ; T-Lymphocytes ; cytology ; metabolism

OBJECTIVETo prepare anti-human IgG-dextran-adriamycin conjugate for immunotargeting of S180 sarcoma and assess its effects on the tumor weight and survival time of the tumor-bearing mice.

METHODSAnti-human IgG-dextran- adriamycin was synthesized by conjugating dextran and adriamycin with anti-human IgG. The immunoactivity of anti-human IgG-dextran-adriamycin was measured by enzyme-linked immunosorbent assay (ELISA), and the cytotoxicity of anti-human IgG, adriamycin, and the IgG-dextran-adriamycin conjugate against the tumor cells in vitro was evaluated using MTT assay. In mice bearing S180 sarcoma, the agents were tested for their effects against tumor cell growth and the survival time of mice.

RESULTSThe molar ratio of anti-mouse IgG, dextran, and adriamycin was 1:2.5:38 in the conjugate. The conjugates were shown to retain the immunoactivity of anti-human IgG, and possessed cytotoxicity to S180 cells in vitro. Administration of the conjugate and intratumor injection of human IgG resulted in a tumor suppression rate of 17.72%in mice bearing S180 sarcoma, but did not prolong the survival time of the mice.

CONCLUSIONThe anti-human IgG-dextran-adriamycin conjugate shows targeted antitumor effect against S180 sarcoma in mice.

Animals ; Antibodies, Anti-Idiotypic ; administration & dosage ; pharmacology ; Antibodies, Monoclonal ; administration & dosage ; pharmacology ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Cell Survival ; drug effects ; Dextrans ; administration & dosage ; pharmacology ; Doxorubicin ; administration & dosage ; pharmacology ; Female ; Immunoglobulin G ; administration & dosage ; pharmacology ; Immunotoxins ; administration & dosage ; pharmacology ; Mice ; Sarcoma 180 ; drug therapy ; pathology ; Survival Analysis ; Tumor Burden ; drug effects

OBJECTIVETo prepare nanospheres coupled with the anti-human liver cancer monoclonal antibody HAb18 and evaluate its immunoreactivity and antitumor effects.

METHODSThe nanosphere coupled with the antibody was prepared by intermolecular cross-linking the anti-human liver cancer monoclonal antibody, HAb18, with human serum albumin nanospheres containing ADM [termed HAS(ADM)-NS] via a new hetero-bifunctional cross-linker SPDP. Condensation test and immunofluorescence assay were used to evaluate the immunoreactivity of the nanospheres, and specific binding of HAb18-HAS(ADM)-NS with liver cancer cell line SMMC-7721 was observed with optical and electron microscopes. The specific cytotoxic effects on the target cells were evaluated in vitro by MTT assay. HAb18-HAS(ADM)-NS, HAS(ADM)-NS and ADM were injected separately into nude mice bearing human liver carcinoma to evaluate the inhibitory activity of HAb18-HAS(ADM)-NS in vivo.

RESULTSThe immunoreactivity of HAb18-HAS(ADM)-NS was well preserved. HAb18-HAS(ADM)-NS could bind specifically with the SMMC-7721 cells. The IC(50) of HAb18-HAS(ADM)-NS against SMMC-7721 cells was 44.6 microg/ml, lower than that of HAS(ADM)-NS (345.5 microg/ml) and ADM (365.5 microg/ml). The inhibition rate of HAb18-HAS(ADM)-NS on the growth of liver cancer xenografts was significantly higher than that of HAS(ADM)-NS and ADM (P<0.001).

CONCLUSIONHAb18-HAS(ADM)-NS has immunoreactivity and can actively and specifically target the liver cancer cells. The antitumor activity of HAb18-HAS(ADM)-NS is significantly higher than that of HAS(ADM)-NS and ADM.

Animals ; Antibodies, Monoclonal ; administration & dosage ; immunology ; Antibodies, Neoplasm ; immunology ; Antineoplastic Combined Chemotherapy Protocols ; immunology ; therapeutic use ; Cell Line, Tumor ; Doxorubicin ; administration & dosage ; immunology ; Female ; Humans ; Immunotoxins ; administration & dosage ; immunology ; Liver Neoplasms ; drug therapy ; immunology ; pathology ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Nanospheres ; administration & dosage ; Treatment Outcome ; Xenograft Model Antitumor Assays ; methods