PROTEASE CLEAVABLE BISPECIFIC ANTIBODIES AND USES THEREOF

The present invention provides recombinant bispecific antibodies designed to bind to a surface antigen on target cells and to an activating component on immune cells such as T cells. The bispecific antibodies comprise two polypeptide chains that contain Fv and Fab as antigen-binding fragments and a modified Fc region to facilitate heterodimer formation In one embodiment, the bispecific antibodies further comprise protease cleavage sites and/or motifs that would cause steric occlusion of the antigen binding sites so that the antibodies would be activated only in a specific environment, e.g. in the vicinity of a tumor. In another embodiment, the bispecific antibodies comprise modified sequences that confer reduced binding affinity to CDS and/or cross-reactive binding to CDS on cells from different species.