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The use of monoclonal antibodies (mAbs) for cancer therapy has achieved considerable success in recent years. Approximate 17 monoclonal antibodies have been approved as cancer therapeutics since 1997. Antibody-drug conjugates (ADC) are powerful new treatment options for cancer, and naked antibodies have recently achieved remarkable success. The safety and effectiveness of therapeutic mAbs in oncology vary depending on the nature of the target antigen and the mechanisms of tumor cell killing. This review provides a summary of the current state of antibody-based cancer therapy, including the mechanisms of tumor cell killing by antibodies, tumor antigens as antibody targets, clinical effectiveness of antibodies in cancer patients and nanoparticles-based ADCs.

Recent studies have shown that epidermal growth factor receptor (EGFR) is an important target for cancer therapy. The present study prepared single chain Fv (scFv) directed against EGFR. Balb/c mice were immunized by human carcinoma A431 cells, and total RNA of the splenic cells was extracted. VH and VL gene fragments were amplified by RT-PCR and further joined into scFv gene with a linker, then scFv gene fragments were ligated into the phagemid vector pCANTAB 5E. The phagemid containing scFv were transformed into electro-competent E. coli TG1 cells. The recombinant phage antibody library was constructed through rescuing the transformed cells with help phage M13K07. The specified recombinant phages were enriched through 5 rounds of affinity panning and the anti-EGFR phage scFv clones were screened and identified with ELISA. A total of 48 clones from the library were selected randomly and 45 clones were identified positive. After infecting E. coli HB2151 cells with one positive clone, soluble recombinant antibodies about 27 kD were produced and located in the periplasm and the supernatant. The result of sequencing showed that the scFv gene was 768 bp, which encoded 256 amino acid residues. VH and VL including 3 CDRs and 4 FRs, respectively, were all homologous to mouse Ig. The soluble scFv showed the specific binding activity to purified EGFR and EGFR located in carcinoma cell membrane. The successful preparation of anti-EGFR scFv will provide an EGFR targeted molecule for the development of antibody-based drugs and biological therapy of cancer.

Background and Objective: Epidermal growth factor receptor (EGFR) is abnormally overexpressed on many kinds of tumor cells. Lidamycin is an enediyne antibiotic with highly potent antitumor activity. This study was to construct a novel fusion protein by recombining EGFR specific oligopeptide ligand and lidamycin, and investigate its antitumor efficacy., Methods: The fusion protein (Ec-LDP) was expressed in E.coli and purified by affinity chromatography. The purity of Ec-LDP was analyzed by high performance liquid chromatography (HPLC). ELISA, flow cytometry (FCM) and immunofluorescence assay were used to analyze the binding activity of Ec-LDP to different cancer cell lines. The energized fusion protein Ec-LDP-AE was prepared by integrating the active enediyne chromophore (AE) of lidamycin into the Ec-LDP protein. The cytotoxicity of Ec-LDP-AE was measured by MTT assay., Results: Ec-LDP fusion protein was successfully constructed and secretorily expressed in E.coli, and the production of Ec-LDP protein was 18 mg per liter fermentation broth. The purity of Ec-LDP protein was 95.3%. Ec-LDP protein had strong binding activity to cancer cell lines highly expressing EGFR, such as MCF-7 and A431 cells. However, Ec-LDP had no binding activity to EGFR negative NIH 3T3 cells. The energized fusion protein Ec-LDP-AE showed potent cytotoxicity to MCF-7 and A431 cells with the half maximal inhibitory concentration (IC50) values of 3.06 x 10(-11) mol/L and 9.38 x 10(-13) mol/L, respectively., Conclusion: The energized fusion protein Ec-LDP-AE binds to EGFR specifically and kills cancer cells efficiently.

Objective: To study the effect of anti-type IV collagenase single-chain antibody scFv (3G11) on bleomycin (BLM)-induced pulmonary fibrosis., Methods: C57BL/6 mice were divided into six groups (blank, saline control, BLM, low-dose treatment, intermediate-dose treatment, and high-dose treatment), the animal model of pulmonary fibrosis was induced with 400 ng/g intratracheal BLM. The day that treatment groups were injected with BLM was marked Day 0. Then at Days 1 - 7, scFv (3G11) was injected once intraperitoneally each day with three dosage [low-dose treatment (15 microg/g), intermediate-dose treatment (30 microg/g) and high-dose treatment (45 microg/g)]. At Day 21, 6 mice of each group (saline control, BLM, intermediate-dose treatment) were sacrificed and pathomorphological changes of left lungs evaluated with HE stained sections. Meanwhile, 6 mice of each group (blank, saline control, BLM, low-dose treatment, intermediate-dose treatment, and high-dose treatment) were sacrificed, the content of hydroxyproline was detected to measure the degree of collagen deposition. Macrophages were extracted from murine abdominal cavity and primarily cultured. And the inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 excretion by different concentrations of scFv (3G11) (0, 15, 30, 45, and 60 micromol/L) was determined by gelatin zymography., Results: By image analysis, the degree of fibrosis in the lungs of treated group was lighter than that of the BLM group. The percentages of the area of interalveolar septum (45.3% +/- 3.2%) and the number of nucleated cells (451 +/- 47) of treated group were remarkably reduced as compared with the BLM group (59.0% +/- 3.0%, 599 +/- 42, both P < 0.01). The content of hydroxyproline of the intermediate-dose treatment group [(0.82 +/- 0.05) microg/mg] and high-dose treatment group [(0.80 +/- 0.03) microg/mg] was lower than that of the BLM group [(0.92 +/- 0.07) microg/mg, P < 0.05, P < 0.01]. The result of gelatin zymography demonstrated that the excretion of MMP-2 and MMP-9 by macrophage was inhibited by scFv (3G11) at the concentration of 15 micromol/L., Conclusion: Single-chain antibody directed against type IV collagenase might inhibit the development of bleomycin-induced pulmonary fibrosis.