Abstract
Abstract Antibody drugs have become the mainstream in drug development. Bi-specific antibodies which specifically bind two therapeutic targets have been shown to be a promising and novel strategy. However, production yield of bi-specific antibodies using IgG structure as the template can be compromised due to unwanted side products. Such a problem may be thwarted by engineering the Fc homodimer into Fc heterodimer designed to be formed with minimized assembly of the former. Previous studies have demonstrated that the formation of heterodimers and reduction in the occurrence of homodimers could be achieved through making a pair of two point mutations K409D/K392D and D399K/E356K in Fc. However, results from this study showed that further optimization is needed to completely inhibit the occurrence of homodimers. In this study, additional point mutations K370D and E357K were found to be needed in addition to the K409D/K392D and D399K/E356K mutations to further reduce the formation of the unwanted homodimers. Thus, a pair of three point mutations K409D/K392D/K370D and D399K/E356K/E357K was employed to establish a method for the expression of antibody heterodimers. EGFR and c-Met are two important targets for the treatment of lung cancer. Combination of EGFR and c-Met inhibitors has been demonstrated to have better therapeutic efficacy. Therefore, production of EGFR/c-Met bi-specific antibody is the main direction of our studies. In this study, the CHO cells expression system was chosen to express a bi-specific antibody that can simultaneously recognize EGFR and c-Met. The result of Mass spectrometry analysis showed the antibodies have good purity, while the results of antigen binding assay and immunoprecipitation analysis showed the antibody has specific binding ability to EGFR and c-Met. Thus, our studies successfully establish a platform for expression of bispecific antibodies.