A bispecific antibody (ScBsAbAgn-2/TSPO) target for Ang-2 and TSPO resulted in therapeutic effects against glioblastomas

• Published in: Biochemical and biophysical research communications 2016-04, Vol.472 (2), p.384-391
• Main Authors: Li, Jia, Zhang, Zhiming, Lv, Lianjie, Qiao, Haibo, Chen, Xiuju, Zou, Changlin
• Format: Article
• Language: English
• Subjects: Agn-2; angiogenesis; angiopoietin-2; Angiopoietin-2 - immunology; Animals; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - therapeutic use; antibody detection; apoptosis; Apoptosis - drug effects; Apoptosis - immunology; brain; Cell Proliferation - drug effects; cytotoxicity; death; endothelium; Glioblastoma; Glioblastoma - drug therapy; Glioblastoma - immunology; Humans; immunotherapy; macrophages; Male; Mice; Mice, Nude; monoclonal antibodies; neoplasm cells; neoplasms; permeability; Rats; Receptors, GABA - immunology; ScBsAbAgn-2/TSPO; screening; T-lymphocytes; Targeted therapy; Treatment Outcome; TSPO
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2016.02.035

Antibody-based targeted therapy of cancers requires the antibody targeting of specific molecules inducing tumor cells apoptosis or death. Angiopoietin-2 (Agn-2) and translocator protein (TSPO) are identified as potential target molecules for glioblastoma therapy. The single chain anti-Agn-2 antibody (Anag-2) and anti-TSPO antibody (ATSPO) were obtained by monoclonal antibody screening. In the present study, for specific targeting and killing, we generated a recombinant bispecific antibody comprising a single-chain Fragment variable (ScFv) of anti-human Agn-2 and anti-human TSPO (ScBsAbAgn-2/TSPO), which is the mediator for mitochondrial apoptosis and tumor angiogenesis. In vitro, ScBsAbAgn-2/TSPO simultaneously bounded to both targets with a high antigen-binding affinity to Anag-2 and TSPO compared to the individual antibody. The higher expression of Ang-2 and TSPO was observed in bevacizumab-treated glioblastoma compared to normal rat brain endothelium. We also observed apoptosis-mediated cytotoxicity was improved, which resulted in the elimination of up to 90% of the target cells within 72 h. ScBsAbAgn-2/TSPO inhibited tumor growth, decreased vascular permeability, led to extended survival, improved pericyte coverage, depletion of tumor-associated macrophages, and increased numbers of intratumoral T lymphocytes infiltration in a murine bevacizumab-treated glioblastoma model. These findings were also confirmed ex vivo using glioblastoma cells from bevacizumab-treated rats with glioblastoma. We conclude that ScBsAbAgn-2/TSPO targeting of glioblastoma cell lines can be achieved in vitro and in vivo that the efficient elimination of glioblastoma cells supports the potential of ScBsAbAgn-2/TSPO as a potent, novel immunotherapeutic agent. •ScBsAbAgn-2/TSPO showed beneficial outcomes for glioblastoma rat.•We provided an improved understanding for apoptotic resistance of glioblastoma.•ScBsAbAgn-2/TSPO significant inhibited glioblastoma tumor growth.•ScBsAbAgn-2/TSPO prolonged the survival of glioblastoma mice.•ScBsAbAgn-2/TSPO improved immunologic cytotoxicity for glioblastoma cells.