Orthogonal Fab BsAb Generation Service

Creative Biolabs specializes in bispecific antibodies (BsAbs) development and manufacture. We offer a full range of BsAbs production services, including orthogonal Fab based BsAb generation. Based on our unique antibody engineering platforms, Creative Biolabs provides world class orthogonal Fab BsAbs. Our techniques combine structure-based design strategy with X-ray crystallography just in order to offer you a pure and well behaved bispecific antibody.

BsAbs enable induce synergistic activities such as co-clustering of signaling receptors or single activities, for example, targeting immune cells to kill cancer cells. Whereas, a variety of existing BsAb formats have drawbacks. For instance, several common BsAb formats, like diabodies, IgG-single-chain (sc) Fv and dual variable domain (DVD)-Ig, change the native antibody geometry with its well-known stability and solubility characteristics to allow specificity for multiple antigens. BsAb formats based on antibody fragments usually need extensive engineering to stabilize the variable domains outside the native Fab context. Besides, on account of the complex multidomain heterodimeric interactions within antibody Fabs, light chain mispairing is a highly serious problem during BsAbs generation.

Figure 1. This figure shows the possible by-products of IgG BsAb assembly. (Lewis, S. M., 2014)

Orthogonal Fab Technique

One method of orthogonal Fab generation is to produce IgG BsAbs with a single light chain, whereas this needs light chain engineering or novel antibody libraries that use a single light chain. Another method is to design an orthogonal heavy chain–light chain interface which enables each light chain combine with its cognate heavy chain with higher affinity than the noncognate heavy chain. It has demonstrated that VH-VL interactions enable to control the interaction specificities between heavy chains and light chains, which may complicate or over-ride any pairing specificity offered by swapping constant domains between heavy chains and light chains. Therefore, developing a fully orthogonal heavy chain –light chain interface may be a more powerful solution for getting the desired heavy chain–light chain specificity. Creative Biolabs has developed an orthogonal IgG heavy chain–light chain interface based on molecular modeling, X-ray crystallography and human-guided design.

Figure 2. Identification of the specificity afforded by the heavy chain–light chain interface designed mutants and the dual binding activity of the resulting BsAb molecules. (Lewis, S. M., 2014)

Orthogonal Fab BsAb Generation

Based the advanced orthogonal Fab based BsAb generation platform, we offer either orthogonal CH1-CL interface or orthogonal VH-VL interface development services. In order to produce a mutant CH1-CL interface which disfavors binding to wild type CH1-CL, we utilized the multistate design application in the modeling program Rosetta. So as to form the VH-VL interface, we mainly performed in two steps: to modify conserved residues wherever possible to make the solutions to be applicable across multiple VH-VL germline segments, and to minimize the impact upon antigen binding.

With the well-established orthogonal Fab platform, the experienced scientists here at Creative Biolabs are dedicated to helping you develop therapeutic BsAbs. We also provide other various services regarding BsAbs development. Please feel free to contact us for more information and a detailed quote.

References

1. Lewis, S. M.; et al. Generation of bispecific IgG antibodies by structure-based design of an orthogonal Fab interface. Nature biotechnology. 2014, 32(2): 191-198.
2. Leaver-Fay, A.; et al. Computationally designed bispecific antibodies using negative state repertoires. Structure. 2016, 24(4): 641-651.