Abzyme’s platform introduces an additional antigen-binding site by fusing a single domain antibody onto the C-terminus of another VHH fragment, a Fab fragment or an IgG Fc of a different specificity to create a so-called Abz2 molecule. This simple rapid fusion transforms an existing antibody into a bispecific antibody without compromising its original target binding affinity. This example shows why the single domain antibody is the key building block of Abzyme Modular Antibody Technology: Abzyme utilizes a VHH C-terminal library to isolate single domain antibodies with desired attributes which are retained after fusion to the C-terminus of the IgG Fc.

Single domain antibody molecules are incredibly versatile, well-expressed and can serve as building blocks for creation of different classes of biologics depending on the therapeutic need including:
• Ideal building blocks to generate bispecific as well as multi-specific antibody molecules
• Abz2 bispecific antibodies
• Each particular single domain that binds to a target of interest is selected and optimized from a camelid single domain antibody library and optimized with enhanced diversity generated by inducible hypermutation

Abz2 bispecifics retain the benefits of a traditional antibody:
• Excellent binding characteristics (affinity, specificity)
• Favorable pharmacokinetics
• Ability to mobilize immune effector functions
• Protein stability
• Low immunogenic potential