Structural and functional characterization of MBS301, an afucosylated bispecific anti-HER2 antibody

ABSTRACTMBS301, a glyco-engineered bispecific anti-human epidermal growth factor receptor 2 (HER2) antibody with a typical IgG1 monoclonal antibody structure, was developed through dual-cell expression and in vitro assembling process. MBS301 consists of two half antibodies engineered from trastuzumab and pertuzumab, respectively. Integrity and purity profiles of MB301 indicated that the heterodimerization of the two half antibodies was successful. The high and similar melting temperatures (Tm1,72.0°C and Tm2, 84.8°C) of MBS301 compared with those of its parental monoclonal antibodies trastuzumab and pertuzumab (in-house made T-mab and P-mab, respectively) revealed its structural compactness. With computer-modeling experiments and Biacore binding and competition kinetics studies, the binding stoichiometry between MBS301 and HER2-ECD was determined to be 1:1 and the two arms of MBS301 were shown to bind to domains II and IV of HER2-ECD antigen simultaneously. MBS301 displayed synergistic bioactivities as th...