Crystal Structure of an Anti-Ang2 CrossFab Demonstrates Complete Structural and Functional Integrity of the Variable Domain.

Bispecific antibodies are considered as a promising class of future
biotherapeutic molecules. They comprise binding specificities for
two different antigens, which may provide additive or synergistic
modes of action. There is a wide variety of design alternatives for
such bispecific antibodies, including the "CrossMab" format.
CrossMabs contain a domain crossover in one of the antigen-binding
(Fab) parts, together with the "knobs-and-holes" approach, to
enforce the correct assembly of four different polypeptide chains
into an IgG-like bispecific antibody. We determined the crystal
structure of a hAng-2-binding Fab in its crossed and uncrossed form
and show that CH1-CL-domain crossover does not induce significant
perturbations of the structure and has no detectable influence on
target binding.