Assessment of the pre-clinical immunogenicity of a new VEGF  receptor Fc-fusion protein FP3 with ELISA and BIACORE.
OBJECTIVE
A new VEGF receptor fusion protein FP3 was shown to have promising antitumor potency better than Bevacizumab. Characterization of its immune response is essential to the safe and effective administration in clinical trials. In this study, both BIACORE and ELISA assays were employed to assess pre-clinical immunogenicity of FP3 in monkeys.


METHODS
Serum samples from 20 rhesus monkeys were analyzed for the generation of anti-FP3 antibody after intravenous administration of three doses of FP3 (n = 6 per group) or buffer control (n = 2). Sera samples were obtained at 2, 4, 6, 8, 10 weeks after the first administration.


RESULTS
It showed BIACORE presented linear correlation with the dilution of anti-FP3 antibody and the results of ELISA. Two weeks after the initial FP3 injection, anti-FP3 antibody was detected in about 20% FP3-treated monkeys. The ratio of positive samples and the titer of antibody increased along with the FP3-treatment time. Six weeks following FP3 injection almost all the samples were anti-FP3 antibody positive. Moreover, the titer of anti-FP3 antibody but not the ratio of positive samples was also enhanced when the dose of FP3 was elevated. Furthermore, the immunoglobulin types and subclasses of anti-FP3 antibody serum components were mainly identified as IgG1 and IgG4, not IgM. Serum antibodies are characterized that they could not block FP3 binding to VEGF and were non-neutralizing.


CONCLUSIONS
Our data implied that proteins with full human sequences may also have the potential to induce immune response in rhesus monkeys, and BIACORE could be an effective approach to detect the immunogenicity of protein therapeutics in clinic.
Wang
Hui
H
State Key Laboratory of Pathogens and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, 100071 Beijing, People's Republic of China. geno0109@vip.sina.com
Shi
Jing
J
Wang
Qin
Q
Li
Hong
H
Cai
Kun
K
Hou
Xiaojun
X
Li
Tao
T
Zhong
Qi
Q
Yu
Dechao
D
D000818:Animals; D000906:Antibodies / Q000097:blood; D000917:Antibody Formation; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000276:immunology*; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000008:administration & dosage / Q000276:immunology*; D008253:Macaca mulatta; D040262:Receptors, Vascular Endothelial Growth Factor / Q000008:administration & dosage / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000276:immunology*
D000906:Antibodies; D000970:Antineoplastic Agents; C557495:FP3 VEGF receptor Fc-fusion protein; D007141:Immunoglobulin Fc Fragments; D011993:Recombinant Fusion Proteins; D040262:Receptors, Vascular Endothelial Growth Factor