Rapid growth in the therapeutic antibody market leads to a drastic development of antibody engineering to optimize biophysical properties. One of the main focuses of biopharmaceutical researches was the expansion of different approaches for affinity maturation of antibodies to enhance biological activity. Adalimumab (D2E7) is an anti-tumor necrosis factor alpha (TNFα) antibody used in the treatment of some autoimmune disorders like rheumatoid arthritis, psoriasis, etc. In this study, by engineering complementary determining regions (CDRs) of D2E7 antibody, we produced a new variant of the antibody with improved affinity and potency to TNFα. We designed four D2E7 mutants that harbored a single point mutation in their CDRs. The native antibody, lc-A94K, lc-A50Y, lc-A33R, and lc-A92R mutant models were transiently produced and characterized. Data showed mutation of ALA to LYS in CDR3 of D2E7 antibody generated new hydrogen bonds with TNFα, thus the lc-A94K model revealed significantly higher binding activity (EC50) and kinetic affinity (KD) to its antigen, in comparison to the wild antibody. Moreover, this model was found to have significantly stronger biological activity (IC50) to activate antibody-dependent cell-mediated cytotoxicity in the mouse fibroblast L929 cells. Secondary structure analysis demonstrated the mutation has no inappropriate conformational impact on the beta and alpha structures of lc-A94K antibody. In conclusion, our study revealed that it is possible to manipulate antibody’s CDRs to increase affinity and potency by single point mutation and also preserve basic structure of the original antibody during CDRs engineering to avoid adverse effects of CDRs mutations on specificity and stability.
Maryam Tabasinezhad, Eskandar Omidinia, Hamzeh Rahimi, Christine Blattner, Torsten H Walther, Fereidoun Mahboudi and Wolfgang Wenzel