Technologies

Germliner™ Platform

Fully Human Antibody Discovery

>>> Epitope-Guided Antibody Humanization

Antibody Optimization

 

Epitope-Guided Antibody Humanization

Most of the antibodies that have been "humanized" by current humanization approaches use a CDR grafting approach, whereby all 6 CDRs from the mouse antibody are grafted onto a human framework. Antibody humanization by CDR grafting often results in decreased binding affinity due to loss of the correct 3-dimensional conformation. Therefore, in the majority of cases, the humanized antibodies still require some critical mouse framework residues to be retained to minimize loss of affinity. These murine sequences are all potentially immunogenic in humans. Moreover, this type of antibody engineering process can cause subtle changes in the antigen-binding pocket resulting in epitope-drift that causes undesirable alterations in antigen selectivity. Epitope drift is largely ignored in summaries of CDR grafting techniques.

In contrast, AvantGen has developed a novel epitope-guided technology that has been validated for humanizing antibodies rapidly. This proprietary approach overcomes the issues facing older humanization methods:

  • Only the CDR-H3 of the monoclonal heavy chain is retained, which maximally removes non-human residues from the humanized antibodies.

  • Focused library is constructed using a validated pairing of human germline VH and VL sequences.

  • The low affinity/specificity of pure germline antibodies is overcome by engineering diversity into key residues in the remaining 5 CDRs.
Antibody humanized by this approach minimizes the likelihood of eliciting anti-antibody reactions in humans, since germline antibody framework sequences are highly tolerated between individuals.

AvantGen’s epitope-guided screening technology provides the additional advantages of allowing rapid selection of humanized antibody candidates. The hits retain the intended epitope-binding specificity while eliminating less specific antibodies exhibiting epitope-drift. The final product is an almost fully human antibody that is less likely to be immunogenic and retains epitope-binding specificity and affinity.

Comparison of chimeric, CDR grafted, and AvantGen humanized antibodies