"Two-in-One" approach for bioassay selection for dual specificity antibodies.

Dual specific antibodies and bispecific antibodies that recognize two different antigen targets are currently being regarded as very effective therapeutics for complex human diseases. While effective, designing and developing a bioassay strategy for dual specific antibodies that is reflective of the mechanism of action (MoA) and also measures the dual activities of antibodies pose unique and exciting challenges. An important question asked while developing a bioassay for dual specific antibodies is, "How many bioassays will be needed, one bioassay or two separate bioassays?" Here we present an approach of using one bioassay for a dual specific antibody that targets two receptors in signaling pathways. The presented assay is able to measure the antibody effects on both target bindings, which would not be achievable using two separate assays. Furthermore, this assay can detect changes in the binding of either target, which impact overall efficacy of the antibody. Its improved sensitivity enables substituting two binding assays with this one bioassay for lot release and stability testing to measure any changes on either target binding, ensuring consistency between lots. This is a single-bioassay approach for a dual specific antibody that is MoA reflective of the intended therapeutic indication. The demonstrated assay development and bridging study strategy for this bioassay for a dual specific mAb1 could be applicable to the other dual specific, bispecific antibodies, and antibodies used for combination therapy.