A fully human CD19/CD3 bi-specific antibody triggers potent and specific cytotoxicity by unstimulated T lymphocytes against non-Hodgkin’s lymphoma

The Epigenetic Regulation of Blinatumomab Gene Expression: Tumor Cell-dependent T cell Response against Lymphoma Cells and Cytotoxic Activity

Conventional treatment for cancer such as surgical resection and chemotherapy can cause damage in cases with advanced cancers. Moreover, the identification of tumor-specific targets has great importance in T-cell therapies. For decades, T cell activity has been stimulated to improve anti-tumor activity. Bispecific antibodies have attracted strong interest from pharmaceutical companies, for their diagnostic and therapeutic use. Blinatumomab is a first-in-class bispecific T engager antibody for the treatment of relapsed or refractory precursor B- cell acute lymphoblastic leukemia. But, it can benefit several cases with CD19⁺ malignancies in the future. PhiC31 integrase-based vectors could selectively integrate therapeutic transgenes into pseudo-attP sites in CHO genome. In this study, production of Blinatumomab in CHO cells using this type of vectors was investigated. We evaluated the effects of histone deacetylases (HDACs) inhibitors such as sodium butyrate and valproic acid, on specific productivity and cell viability of antibody expressing cells. Although sodium butyrate increased specific productivity about 1.7-fold and valproic acid about 1.4-fold, valproic acid was found more efficient because of its less cytotoxic effect on cell growth. We examined the efficacy of expressed Blinatumomab at various effector to target (E/T) ratios. A dose-response analyses of calcein-acetoxymethyl release assay illustrated that the effective dose of expressed mAb required for antibody mediated cytotoxicity was 100 ng/ml and the expressed mAb was more effective at E/T ratios of 10:1 and 5:1. Results of this study indicated that the expressed blinatumomab can be useful for enhancing the cytotoxicity of CD3⁺ T-cells against CD19 ⁺ target cells in vitro.

Construction and functional analysis of an anti-human cervical carcinoma/anti-human CD3 single-chain bispecific antibody

The aim of the present study was to construct a single-chain bispecific antibody (scBsAb) against cervical carcinoma and to investigate its biological activities. The scBsAb was constructed using a genetic cloning technique and antigen binding activities were detected by ELISA. The iodogen method was used to analyze the pharmacokinetics. The Rosette formation test was used to detect the binding ability between peripheral blood lymphocytes (PBLs) and Cs1213 cervical cancer cells. In addition, the MTT method was performed to detect the killing effect of PBLs. The molecular weight of the scBsAb was ~60 kDa. The antigen binding activities of scBsAbs were compared with the anti‑human cervical carcinoma antibody single‑chain Fv fragment (CSAs‑1 scFv) and anti‑cluster of differentiation (CD)3 scFv (P>0.05). In addition, a pharmacokinetics assay demonstrated that compared with the two corresponding scFvs, scBsAbs exhibited a significantly prolonged retention time in the body (P<0.01). In addition, the number of rosettes formed by PBLs and Cs1213 cells in the scBsAb group was markedly greater than that in the scFv groups or the RPMI‑1640 group (P<0.05 and P<0.01, respectively). The killing activity of PBLs against scBsAb‑mediated Cs1213 cells was significantly greater than that mediated by the other antibodies (P<0.05). When the concentration of scBsAb was 40 µg/ml, the killing rate was 64.5%. Thus, anti‑human cervical carcinoma/anti‑CD3 scBsAbs may possess two types of antigen binding activity, prolong the duration in vivo and improve the killing activity of PBLs against cancer cells.

The preparation of VEGFR1/CD3 bispecific antibody and its specific cytotoxicity against VEGFR1-positive breast cancer cells

Bispecific antibody (BsAb) has been proved to be a very effective antitumor approach because of its distinctive advantages of immune-mediated cytotoxicity. To enhance the ability to recruit and activate T lymphocytes for tumor-specific killing, we constructed and prepared a recombinant human single-chain Fv bispecific antibody (BsAb), named VEGFR1/CD3 BsAb, targeting VEGFR1 and CD3. The VEGFR1/CD3 BsAb was expressed in CHO-K1 cells and purified by Ni-NTA affinity chromatography. The CD3 and VEGFR1-binding activity of VEGFR1/CD3 BsAb was confirmed by flow cytometry. T lymphocyte activation and proliferation induced by VEGFR1/CD3 BsAb were also demonstrated in vitro. Notably, our VEGFR1/CD3 BsAb presented a powerful and specific killing effect against VEGFR1-positive human breast cancer cell MDA-MB-231 and MDA-MB-435 through activating T lymphocyte at very low concentrations, indicating that it will be a valuable antibody drug for treatment of VEGFR1-positive cancers in the future.