Scientists from Creative Biolabs have successfully produced all three types of bispecific antibodies using well-established methods. According to customer's detailed requirements, Creative Biolabs will design and perform the most suitable approach to fulfil client's demands.
Fig. 1. Various types of bispecific antibodies (Kontermann 2015)
Of the two paratopes that form the tops of the variable domains in bispecific antibody, one can be directed against a tumour antigen and the other against a T lymphocyte antigen like CD3. In the case of trifunctional antibodies, the intact Fc region additionally binds to a cell that expresses Fc receptors like macrophage, a natural killer cell or a dendritic cell. In summary, through bispecific antibody, the tumour cell is connected to one or two cells of the immune system, leading to their destruction.
Comparing to the ordinary monoclonal antibodies, the ordinary ones can't activate T lymphocytes. Because there are no Fc receptors on T lymphocytes, the Fc region of ordinary monoclonal antibody can't bind to them, and the Fab regions are already used for binding the tumour cells. As a result, the bispecific antibody shows advantage in cancer immunotherapy over ordinary monoclonal antibody. Besides, bispecific antibodies have a higher cytotoxic potential. They are able to bind antigen that are expressed relatively weakly. It's common that bispecific antibody can have an effective dose several orders of magnitude lower than ordinary antibodies.