Novel biologics that redirect cytotoxic T lymphocytes (CTLs) to kill tumor cells bearing a tumor associated antigen hold great promise in the clinic. However, the ability to safely and potently target CD3 on CTL toward tumor associated antigens (TAA) expressed on tumor cells remains a challenge of both technology and biology. Herein we describe the use of a Half DVD-Ig format that can redirect CTL to kill tumor cells. Notably, Half DVD-Ig molecules that are monovalent for each specificity demonstrated reduced non-specific CTL activation and conditional CTL activation upon binding to TAA compared to intact tetravalent DVD-Ig molecules that are bivalent for each specificity, while maintaining good drug like properties and appropriate PK properties.
Animals ; Antibodies, Bispecific ; immunology ; Antibodies, Monoclonal ; immunology ; pharmacokinetics ; CD3 Complex ; metabolism ; Cell Line, Tumor ; Cytotoxicity, Immunologic ; ErbB Receptors ; metabolism ; Female ; Humans ; Lymphocyte Activation ; immunology ; Mice, SCID ; Neoplasms ; immunology ; pathology ; Rats, Sprague-Dawley ; T-Lymphocytes, Cytotoxic ; immunology

To enhance the specificity of anti-TNF-α single chain Fv antibody (TNF-scFv) to inflamed site, we constructed a bispecific antibody BsDb that targets TNF-α and ED-B-containing fibronectin (B-FN) by covalently linking TNF-scFv and the anti-ED-B scFv L19 at the gene level via a flexible peptide linker deriving from human serum albumin. BsDb was successfully secreted from Pichia pastoris as functional protein, identified by immunoblotting, and purified to homogeneity with affinity chromatography. BsDb retained the immunoreactivity of its original antibodies TNF-scFv and L19, and showed a marked gain in antigen-binding affinity and in TNF-α-neutralizing ability, when compared to TNF-scFv and L19 that were produced in Escherichia coli. In the adjuvant-induced arthritis (AIA) mice model, BsDb showed selective accumulation and retention in the inflamed paws but rapid clearance from blood, resulting in high arthritic paw to blood ratios. These data indicate that BsDb is endowed with high specificity to inflamed site and low toxicity to normal tissues and holds great potential for in vivo application for the targeted therapy of RA and other chronic inflammatory diseases.
Animals ; Antibodies, Bispecific ; biosynthesis ; immunology ; Antibodies, Neutralizing ; biosynthesis ; immunology ; Escherichia coli ; Fibronectins ; chemistry ; immunology ; Humans ; Mice ; Single-Chain Antibodies ; biosynthesis ; immunology ; Tumor Necrosis Factor-alpha ; immunology

Tumor surface antigen human epidermal growth factor receptor 2 (Her2) is a type I receptor tyrosine kinase, which belongs to human epidermal growth factor receptor family. Her2-overexpression is associated with tumorigenesis and metastasis. Due to significant clinical effects, Her2-targeted cancer therapy especially therapeutic antibody has become the hot spot in the field of cancer treatment. Anti-Her2 antibody drugs include monoclonal antibodies, antibody-drug conjugates, bispecific antibodies and emerging "two in one" antibody. Based on structure and function of Her2, this review focuses on recent advances in active mechanisms and clinical researches of these antibodies.
Antibodies, Bispecific ; therapeutic use ; Antibodies, Monoclonal ; therapeutic use ; Humans ; Immunoconjugates ; therapeutic use ; Neoplasms ; drug therapy ; Receptor, ErbB-2 ; immunology

In order to obtain the lead compound for treatment of rheumatoid arthritis (RA), in this study, therapeutic efficacy of three bispecific antibodies (BsAB-1, BsAB-2 and BsAB-3) against both hIL-1beta and hIL-17 were compared on CIA model mice. First, by ELISA method we compared the binding capacity of the three bispecific antibodies to the two antigens. The results showed that all three antibodies could simultaneously bind both antigens, among these antibodies, BsAB-1 was superior over BsAB-2 and BsAB-3. CIA model was established with chicken type II collagen (CII) and developed RA-like symptoms such as ankle swelling, skin tight, hind foot skin hyperemia. The CIA mice were treated with three antibodies once every two days for total of 29 days. Compared with the CIA model mice, the RA-like symptoms of the antibody treated-mice significantly relieved, while the BsAB-1 treated-mice were almost recovered. CII antibody level in the serum and cytokines (IL-2, IL-1beta, IL-17A and TNF-alpha) expression in the spleen were examined. Compared with the CIA model mice, all three antibodies could significantly reduce CII antibody and cytokine expression levels. BsAB-1 antibody was more potent than BsAB-2 and BsAB-3. In summary, BsAB-1 is superior over BsAB-2 and BsAB-3 in amelioration of RA symptoms and regulation of CII antibody production and pro-inflammatory cytokine expression, therefore, BsAB-1 can be chosen as a lead compound for further development of drug candidate for treatment of RA.
Animals ; Antibodies ; metabolism ; Antibodies, Bispecific ; immunology ; therapeutic use ; Antigen-Antibody Reactions ; Arthritis, Experimental ; chemically induced ; metabolism ; therapy ; Arthritis, Rheumatoid ; chemically induced ; metabolism ; therapy ; Collagen Type II ; immunology ; Interleukin-17 ; metabolism ; Interleukin-1beta ; metabolism ; Interleukin-2 ; metabolism ; Male ; Mice ; Spleen ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

We present a bispecific antibody that recognizes an antigen and a hapten and can be applied to various biological assays, including immunoblotting and immunoprecipitation. In immunoblot analysis of serum, an anti-C5 x anti-cotinine bispecific tandem single-chain variable fragment (scFv)-Fc fusion protein and cotinine-conjugated horseradish peroxidase (HRP) generated a clean signal without the high background that was observed in a parallel experiment using HRP-conjugated goat anti-rabbit immunoglobulin G (Fc-specific) antibody. In immunoprecipitation analysis of serum, use of the bispecific tandem scFv-Fc fusion protein and cotinine-crosslinked magnetic beads significantly reduced the amount of protein contaminants compared with a parallel experiment done with protein A agarose beads. In subsequent immunoblot analysis, use of cotinine-HRP as the secondary probe instead of HRP-conjugated goat anti-rabbit IgG (Fc-specific) antibody successfully eliminated the band corresponding to the bispecific tandem scFv-Fc fusion protein.
Animals ; Antibodies, Bispecific/*immunology ; HEK293 Cells ; Haptens/*immunology ; Humans ; Immunoblotting/*methods ; Immunoprecipitation/methods ; Rabbits ; Single-Chain Antibodies/immunology

Bispecific antibodies have been exploited as both cancer immunodiagnostics and cancer therapeutics, which have shown promises in clinical trials in cancer imaging and therapy. To improve the anti-tumor effect, an scDb (bispecific single-chain diabody) was constructed from the variable domain genes of two scFvs (single-chain variable fragment antibodies) directed against human EGFR (epidermal growth factor receptor) and VEGFR2 (vascular endothelial growth factor receptor 2) extracellular domains. The anti-EGFR/ anti-KDR scDb was constructed into pHEN2 plasmid and expressed in Escherichia coli HB2151 host. After purification by one-step affinity chromatography of IMAC, scDb protein was characterized by Western blotting. The yield of scDb protein was 570 microg per liter medium. scDb bound to EGFR as efficiently as the parental antibody scFv-E10, while a little bit weaker than the parental antibody scFv-AK404R when bound to KDR. In conclusion, the scDb protein could bind both EGFR and KDR specifically and could be applied for further anti-tumor research.
Antibodies, Bispecific ; biosynthesis ; genetics ; Escherichia coli ; metabolism ; Humans ; Plasmids ; Protein Binding ; Receptor, Epidermal Growth Factor ; immunology ; Single-Chain Antibodies ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor Receptor-2 ; immunology

OBJECTIVETo analyze the drift of T cell receptor (TCR) Vα and Vβ gene family CDR3 spectratype in response to ovarian carcinoma cells mediated by an anti-human ovarian carcinoma/CD3 bispecific single-chain antibody (BHL-1), and explore the mechanism of the bispecific single-chain antibody-mediated T cell immune response.

METHODSImmunoscopic spectratyping technique was used to analyze the TCR repertoire diversity (CDR3 spectratype distribution) of the T cells from 6 healthy donors before and after stimulation of the cells with human ovarian carcinoma in the presence of BHL-1. The predominant usage of TCR α and Vβ chain CDR3 was analyzed after the stimulation, and sequence analysis was performed for the CDR3 region of the monoclonal T cells.

RESULTSThe spectratypes of Vα and Vβ gene family TCR CDR3 region showed a Gaussian distribution before stimulation of the T cells from the 6 donors. After stimulation of the T cells, CDR3 spectratype drift occurred in the T cells, and some TCR Vα and Vβ families showed an anomalous and oligoclonal expansion. Different CDR3 sequences of the Vα and Vβ gene family TCR were found in the monoclonal T cells stimulated with BHL-1.

CONCLUSIONCDR3 spectratype drift occurs in TCR α and Vβ chains of T cells after stimulation with human ovarian carcinoma cells and BHL-1, indicating that the predominant usage of TCR Vα and Vβ families is associated with the specific T cell immune response mediated by BHL-1.

Antibodies, Bispecific ; immunology ; Cell Line ; Cell Line, Tumor ; Complementarity Determining Regions ; immunology ; Female ; Humans ; Monocytes ; immunology ; Ovarian Neoplasms ; immunology ; Receptors, Antigen, T-Cell, alpha-beta ; immunology ; Single-Chain Antibodies ; immunology

We constructed and expressed an anti-CD3/anti-Pgp (P-glycoprotein) diabody previously. However, the two chains of diabody are associated non-covalently, resulting in being capable of dissociating. The aim of this study is to enhance the stability of the diabody. We introduced cysteine residues into the CD3 or Pgp V-domain to covalently lock the two chains together. The disulphide crosslinked diabody were expressed by Escherichia coli (E. coli) 16C9 and purified by a cation exchange column and an anti-Etag affinity chromatography. The purified proteins were verified through SDS-PAGE. Flow cytometry (FCM) was used to analyse the binding properties, competitive binding capacity and stability in vitro. The dsPpg-diabody failed to form disulphide bond properly. The designed disulphide bridge between the different chains of dsCD3-diabody was formed correctly. FCM demonstrated the dsCD3-diabody has specific antigen binding activity, the same binding activity and competitive binding activity as its parent diabody. The dsCD3-diabody retained the full activity even after 72 h incubation at 37 degrees C in human serum, in contrast, the parent diabody began to lose activity after only 1 h and lose all its activity 24 hours later. The induced disulphide bond in the CD3 V-domain effectively enhanced the stability of anti-CD3/anti-Pgp diabody. The method of stabilizing a diabody by introducing a disulphide bond into is practical.
ATP Binding Cassette Transporter, Sub-Family B ; immunology ; Antibodies, Bispecific ; biosynthesis ; chemistry ; genetics ; immunology ; Binding, Competitive ; CD3 Complex ; immunology ; Cell Line ; Disulfides ; chemistry ; Drug Stability ; Escherichia coli ; genetics ; metabolism ; Humans

Several studies have demonstrated the role of 4-1BBL in T cell activation. Furthermore, enhanced 4-1BB/4-1BBL interaction has been shown to amplify T-cell-mediated antitumor immunity in several mouse models. However, when applied in humans, it was difficult to generate sufficient T cells ex vivo and whole cell vaccines to transfer back into patients. To overcome this difficulty, we have focused on producing the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein. In this report, PCR and overlap PCR were used to construct the human 4-1BBL extracellular domain/anti-CD20 Fab' expression vector. DNA sequence was analyzed by the Terminus of Dideoxy Nucleotide. The product was purified by affinity chromatography and analyzed by SDS-PAGE and HPLC; its antigen binding activity was examined by rosetting assay. The data of DNA sequence showed that the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein was corrected. The fusion protein was recovered in high yield (up to 200 microg/mL) after E-taq purification. The fusion protein was capable of simultaneous binding to stimulated Jurkat cells and Raji cells as shown by cellular rosetting. In conclusion, the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein was induced to express in E. coli 16C9. The results of some biological activity experiments indicated that the fusion protein could bind to stimulated Jurkat cells and Raji cells. Furthermore, 4-1BBL-negative tumors can be converted into 4-1BBL-positive tumors by the fusion protein without the need for 4-1BBL gene transfer to the malignant cells.
4-1BB Ligand ; biosynthesis ; genetics ; Antibodies, Bispecific ; immunology ; Antigens, CD20 ; immunology ; Humans ; Immunoglobulin Fab Fragments ; biosynthesis ; genetics ; Immunotherapy ; methods ; Lymphoma, Non-Hodgkin ; therapy ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology

OBJECTIVETo study and compare the biologic activity of two anti-PSA/anti-CD3 bispecific single-chain antibodies.

METHODSFlow cytometry (FCM) was used to detect the binding activity of two antibodies to CD3-positive cell line Jurkat and prostate carcinoma cell line LNCaP. The effect of the two antibodies in mediating tumor cell lysis in vitro was determined by using the 51Cr-release test. For in vivo evaluation of the two antibodies activity, a nude mouse model was used. The mice were inoculated with LNCaP prostate cancer cells.

RESULTSFCM showed that both the antibodies could bind Jurkat and LNCaP cells with high specificity. The percentages of the cells bond by the bispecific single-chain antibodies were 56.3% and 55.4%, and those by the multivalent antibodies were 74.0% and 83.0% respectively. Both the antibodies mediated a specific lysis of LNCaP cells in vitro, with activated CTLs as effector cells, and significantly reduced tumor growth of nude mice in vivo as compared with the untreated controls and the group treated with CTLs only (P <0.05). The experiment also showed that the multivalent antibody had a better activity than the bispecific antibody in binding antigens, mediating lysis of LNCaP cells and reducing tumor growth (P < 0.05).

CONCLUSIONBoth the anti-PSA/anti-CD3 bispecific single-chain antibody and multivalent antibody have good biologic activity, and the formation of the tetramerization of single-chain antibody can improve its biologic activity.

Animals ; Antibodies, Anti-Idiotypic ; immunology ; Antibodies, Bispecific ; immunology ; pharmacology ; CD3 Complex ; immunology ; Cytotoxicity, Immunologic ; immunology ; Flow Cytometry ; Humans ; Jurkat Cells ; Male ; Mice ; Mice, Nude ; Prostate-Specific Antigen ; immunology ; Prostatic Neoplasms ; immunology ; pathology