Exploring the Immunological Mechanisms Underlying the Anti-vascular Endothelial Growth Factor Activity in Tumors

Several studies report the key role of the vascular endothelial growth factor (VEGF) signaling on angiogenesis and on tumor growth. This has led to the development of a number of VEGF-targeted agents to treat cancer patients by disrupting the tumor blood vessel supply. Of them, bevacizumab, an FDA-approved humanized monoclonal antibody against VEGF, is the most promising. Although the use of antibodies targeting the VEGF pathway has shown clinical benefits associated with a reduction in the tumor blood vessel density, the inhibition of VEGF-driven vascular effects is only part of the functional mechanism of these therapeutic agents in the tumor ecosystem. Compelling reports have demonstrated that VEGF confers, in addition to the activation of angiogenesis-related processes, immunosuppressive properties in tumors. It is also known that structural remodeling of the tumor blood vessel bed by anti-VEGF approaches affect the influx and activation of immune cells into tumors, which might influence the therapeutic results. Besides that, part of the therapeutic effects of antiangiogenic antibodies, including their role in the tumor vascular network, might be triggered by Fc receptors in an antigen-independent manner. In this mini-review, we explore the role of VEGF inhibitors in the tumor microenvironment with focus on the immune system, discussing around the functional contribution of both bevacizumab's Fab and Fc domains to the therapeutic results and the combination of bevacizumab therapy with other immune-stimulatory settings, including adjuvant-based vaccine approaches

Alternative Methods to Animal Use for Monoclonal Antibody Generation and Production

Monoclonal antibody (mAb) has broad applicability in research, diagnosis, and treatment. After the introduction of hybridoma technology in 1975, the mAb market has increased dramatically, moving a large industry of more than US$ 140 billions in 2020. In 1954, the concept of the 3R’s was proposed and much changed the animal use scenario, including the recent ban on inducing ascites in mice for the production of mAb. In light of this, the generation and production of antibodies had to be reassessed. In this chapter, we present an overview of the main alternative technologies to the use of animals in the generation and production of mAb. Antibody display libraries and in silico modeling are very promising technologies that may provide mAb genetic constructs that, in the sequence, may be expressed on mammalian, bacterial, yeast or plant systems. Although the total replacement of the use of animals in the entire process is not currently feasible, it is possible to find ways to reduce and refine the use of animals in obtaining and producing mAb

Humoral immune response after genetic immunization is consistently improved by electroporation

Aiming to evaluate some parameters to influence the immune response to DNA vaccination, we compare three protocols of DNA immunization (i.m. injections, i.m. injections followed by electroporation, and the effect of i.p. injection of stably antigen-transfected cells before DNA administration), using three different antigens. Statistical analyses showed that electroporation after intramuscular injections provided an immune response comparable to that obtained by pre-treatment with antigen-transfected cells and similar to that obtained by protein immunization. the results allowed us selecting a protocol that worked well for all three antigens and reinforced the idea that high level of gene expression is essential to get good immunization. (c) 2008 Elsevier B.V. All rights reserved.Universidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, CINTERGEN, Interdisciplinary Ctr Gene Therapy, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, CINTERGEN, Interdisciplinary Ctr Gene Therapy, BR-04023062 São Paulo, BrazilWeb of Scienc

Carcinoembryonic antigen (CEA) mimicry by an anti-idiotypic scFv isolated from anti-Id 6.C4 hybridoma

Since carcinoembryonic antigen (CEA) is expressed during embryonic life, it is not immunogenic in humans. the use of anti-idiotypic (Id) antibodies as a surrogate of antigen in the immunization has been considered a promising strategy for breaking tolerance to some tumor associated antigens. We have described an anti-Id monoclonal antibody (MAb), designated 6.C4, which is able to mimic CEA functionally. the anti-Id MAb 6.C4 was shown to elicit antibodies that recognized CEA in vitro and in vivo. in the present study, we sought to verify whether a single chain (scFv) antibody obtained, the scFv 6.C4, would retain the ability to mimic CEA. Two scFv containing the variable heavy and light chain domains of 6.C4 were constructed with a 15-amino acid linker: one with and another without signal peptide. DNA immunization of mice with both forms of scFv individually elicited antibodies able to recognize CEA. (c) 2006 Elsevier B.V. All rights reserved.Universidade Federal de São Paulo, Dept Biophys, São Paulo, BrazilUniversidade Federal de São Paulo, Interdisciplinary Ctr Gene Therapy, São Paulo, BrazilHosp Canc AC Camargo, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, São Paulo, BrazilUniversidade Federal de São Paulo, Interdisciplinary Ctr Gene Therapy, São Paulo, BrazilWeb of Scienc

Impaired proliferation and migration of HUVEC and melanoma cells by human anti-FGF2 mAbs derived from a murine hybridoma by guided selection

ABSTRACTDisadvantages of using murine monoclonal antibodies (mAb) in human therapy, such as immunogenicity response, led to the development of technologies to transform murine antibodies into human antibodies. The murine anti-FGF2 3F12E7 mAb was proposed as a promising agent to treat metastatic melanoma tumors; once it blocks the FGF2, responsible for playing a role in tumor growth, angiogenesis, and metastasis. Considering the therapeutic potential of anti-FGF2 3F12E7 mAb and its limited use in humans due to its origin, we used this antibody as the template for a guided selection humanization technique to obtain human anti-FGF2 mAbs. Three Fab libraries (murine, hybrid, and human) were constructed for humanization. The libraries were phage-displayed, and the panning was performed against recombinant human FGF2 (rFGF2). The selected human variable light and heavy chains were cloned into AbVec vectors for full-length IgG expression into HEK293-F cells. Surface plasmon resonance analyses showed binding to rFGF2 of seven mAbs out of 20 expressed. Assays performed with these mAbs resulted in two that showed proliferation reduction and cell migration attenuation of HUVEC and SK-Mel-28 melanoma cells. In-silico analyses predicted that these two human anti-FGF2 mAbs interact with FGF2 at a similar patch of residues than the chimeric anti-FGF2 antibody, comprehending a region within the heparin-binding domains of FGF2, essential for its function. These results are comparable to those achieved by the murine anti-FGF2 3F12E7 mAb and showed success in the humanization process and selection of two human mAbs with the potential to inhibit undesirable FGF2 roles

Synergistic effect of vascular endothelial growth factor and granulocyte colony-stimulating factor double gene therapy in mouse limb ischemia

10 p. : il.Background Vascular endothelial growth factor (VEGF) has mostly been tested to treat ischemic diseases, although the outcomes obtained are not satisfactory. Our hypothesis is that the local transient expression of VEGF and stem cell mobilizer granulocyte colony-stimulating factor (G-CSF) genes in ischemic limbs can complement their activities and be more efficient for limb recovery. Methods Limb ischemia was surgically induced in mice and 50 μg of VEGF and/or G-CSF genes were locally transferred by electroporation. After 3–4 weeks, evidence of necrosis by visual inspection, capillary density, muscle mass, muscle force and hematopoietic cell mobilization were evaluated. Results After 4 weeks, 70% and 90% of the animals of the ischemic group (IG) and VEGF-treated group (VG), respectively, presented limb necrosis, in contrast to only 10% observed in the group of mice treated with both VEGF and G-CSF genes (VGG). Recovery of muscle mass and muscle force was higher than 60% in the VGG compared to the non-ischemic group. The mobilization of Sca1+ cells and neutrophils was also higher in the VGG, which may explain the lower level of necrosis observed in this group (22%, in contrast to 70% in the IG). Capillary density and degree of fibrosis were determined in weeks 3 and 4, and also showed a clear benefit as a result of the use of the G-CSF and VEGF genes together. Conclusions Gene therapy using VEGF and G-CSF demonstrated a synergistic effect promoting vessel and tissue repair in mouse hind limb ischemia. Copyright  2010 John Wiley & Sons, Ltd