Modifications and challenges for Bispecific Antibodies and the potential solutions for developing PK assays
Antibody-based therapeutics are evolving from monoclonal antibodies to antibody derivatives with complex structures to achieve advanced therapeutic effects.
The complexity of Bispecific Antibodies (bsAbs) is due to the antibodies’ containing two different binding domains, which allow them to simultaneously target two distinct antigens. Understanding their pharmacokinetics (PK) requires a sophisticated bioanalytical approach to characterize the whole drug and each functional domain. The challenges and strategies associated with characterizing these complex molecules:
- Due to their bispecific nature, PK assays for bsAbs can consist of three components:
- Total Ab Assay: Target using only one binding domain.
- Bi-Functional Assay: Measures both active binding domains. (HTRF, MSD)
- Mono-Functional Assays: Two separate assays, each targeting one binding domain.
- Bioanalytical Challenges:
- BsAbs are vulnerable to in vivo biotransformation, affecting their pharmacokinetics.
- Traditional ligand binding assays face challenges due to increased complexity.
- New bioanalytical techniques are needed to address these complexities.
- Promising Approaches:
- Mechanism of Action (MoA)-Based Assays: Develop PK assays based on the bsAb’s MoA.
- Critical Monoclonal Anti-Idiotypic (Anti-ID) Antibodies: Use these as surrogate positive controls for anti-drug antibody (ADA) responses.
- Evaluate the impact of ADA responses on bsAb exposure pre-clinically to make sure the PK curves
- Evaluate the impact of ADA responses on bsAb exposure pre-clinically to interpret the ADA impact on PK.
In summary, PK assays for biotherapeutic bispecific antibodies require innovative approaches to handle their complexity. Sword Bio has done these approaches. If you’d like more details or specific aspects covered visit our PK page here