A Novel Fc-Engineered Anti-HER2 Bispecific Antibody With Enhanced Antitumor Activity.

Human epidermal growth factor receptor 2 (HER2) overexpression has been demonstrated in a variety of cancers. Targeted therapy with anti-HER2 monoclonal antibodies (mAbs) has been approved as a therapeutic modality. Despite the efficacy of mAbs in tumor treatment, many patients do not benefit from this therapeutic platform. Fragment crystallizable (Fc) engineering is a common approach to improve the efficacy of therapeutic mAbs. Five Fc-engineered mAbs have so far been approved by FDA. We have recently developed an anti-HER2 bispecific mAb, BiHT, constructed from variable domains of trastuzumab, and our novel humanized anti-HER2 mAb, hersintuzumab. BiHT displayed promising antitumor activity as potently as the combination of the parental mAbs. Here, we aimed to modify the Fc of BiHT to improve its therapeutic efficacy. The Fc-engineered BiHT (MBiHT) bound to recombinant HER2 and its subdomains with an affinity similar to BiHT. It also recognized native HER2 on different cell lines, inhibited their proliferation, downregulated HER2 expression, and suppressed downstream signaling pathways similar to BiHT. Compared with BiHT, MBiHT displayed enhanced antibody-dependent cellular cytotoxicity activity against various tumor cell lines. It also inhibited the growth of ovarian xenograft tumors in nude mice more potently than BiHT. Our findings suggest that MBiHT could be a potent therapeutic candidate for the treatment of HER2-overexpressing cancer types.

Monoclonal antibody directed to the PilQ -PilA DSL region in Pseudomonas aeruginosa improves survival of infected mice with antibiotic combination.

The infections caused by Pseudomonas aeruginosa are related to high mortality and morbidity in critically ill patients because of multidrug resistance. Thus, we performed the efficacy of the monoclonal antibody (mAb) against PilQ -PilA DSL region (QA) in combination with antibiotics in a model of P. aeruginosa infection. In the present study, three clinically applicable antibiotics (levofloxacin, ceftazidime and gentamicin) and the anti-QA mAb were utilized for treatment of P. aeruginosa sepsis in mice. Reliably, in comparison with other treatment groups (antibody or antibiotic administration), the combination of antibiotic and anti-QA mAb essentially enhanced the survival of mice infected with P. aeruginosa PAO1. This synergistic effect was due to improved bactericidal effect, which prevented bacterial dissemination to different organs. Consequently, the antibiotic and anti-QA mAb combination gives a new effective strategy for the treatment of P. aeruginosa sepsis, particularly when large numbers of exceptionally virulent strains are present.

A novel mAb against a human CD34 peptide reacts with the native protein on CD34+ cells.

BACKGROUND: Human CD34 is a transmembrane glycoprotein which is expressed in human hematopoietic stem cells (HSCs) and the small- vessel endothelial cells of a variety of tissues. CD34 plays a critical role as a marker for diagnosis and classification of leukemia. Anti CD34 antibodies are used for isolation and purification of HSCs from bone marrow, peripheral blood and cord blood. OBJECTIVE: To characterize a newly produced monoclonal antibody against a human CD34 peptide. METHODS: Anti CD34 monoclonal antibody (Clone 2C10-D3) was purified from mouse ascitic fluid and hybridoma cell culture supernatants by affinity chromatography and its immune reactivity was examined by ELISA. The purified antibody was further characterized using Western blot and flow cytometry on TF1 (Human Erythroblast) cell line. RESULTS: ELISA experiment revealed that the antibody recognized CD34 peptide. Western blot analysis on TF1 cell lysate confirmed the reactivity of the antibody with a 42 KDa protein. Blocking the antibody with a saturating concentration of specific CD34 peptide resulted in loss of its activity with TF1 lysate in Western blot. The 2C10-D3 antibody reacted with TF1 cells in flow cytometry in a similar manner to a commercial anti CD34 monoclonal antibody. CONCLUSIONS: Our data suggest that the anti CD34 monoclonal antibody (Clone 2C10-D3) is an appropriate antibody to study the CD34+ cells by flow cytometry and Western blot.