Bispecific Antibody (BsAb) Design Service for Protein Mimetic

As a leading supplier in the antibody field, Creative Biolabs specializes in designing and producing high-quality bispecific antibody (BsAb) products. Our dedicated scientists are focused on delivering customized, top-tier BsAb solutions tailored for protein mimicry.

Introduction

BsAbs, with their bivalent composition, bind two distinct antigens or proteins, bringing them together into a single complex. One of the important functions of BsAbs is to act as a protein mimetic. This function is valuable when two factors need to contact each other for biological processes, allowing BsAbs to mimic protein functions and modulate signaling events for therapeutic purposes, such as enhancing immune responses or inhibiting tumor growth.

Mechanism of BsAbs for Protein Function Mimetic

As protein mimetics, BsAbs mimic protein function by leveraging their dual-targeting capability and can recreate interactions between molecules required for specific signaling pathways. By binding two distinct antigens, BsAbs can physically bridge them, effectively forming a functional complex. This action replicates the role of a natural protein that would otherwise bring these antigens together. For instance, a BsAb can link two proteins necessary for a specific signaling cascade, substituting for a deficient or absent bridging protein. This allows the BsAb to restore or induce a desired biological activity, acting as a functional protein mimic.

Fig.1 BsAbs acting as a co-factor mimetic.^1,4

Technologies Used in Mimetic BsAbs Development

One prominent technology is the Knobs-into-holes (KIH) technique. This frequently used technique tackles heavy chain mispairing by inducing mutations in the two parental antibodies' CH3 domains. Specifically, amino acid residues with large side chains ("knobs") are engineered into one CH3 domain, while corresponding residues with smaller side chains ("holes") are introduced into the other.

This steric complementarity drives the preferential heterodimerization of the modified heavy chains over homodimerization, significantly increasing the yield of the desired BsAb. The KIH technology offers the advantage of utilizing the natural Fc region, preserving effector functions if required and facilitating downstream purification processes similar to conventional monoclonal antibodies.

Fig.2 KIH design of heterodimeric BsAb.^2,4

scFv-based formats link the variable heavy and light chain domains of each antibody with a short peptide linker. These scFvs can then be assembled into various bispecific constructs, such as tandem scFvs or diabodies. These smaller formats often exhibit better tissue penetration but may have shorter serum half-lives compared to Fc-containing antibodies.

Published Data

The study developed asymmetric IgG BsAbs targeting FIXa and FX to mimic FVIII cofactor function. Although the initial therapeutic potential was limited, binding properties to FIXa and FX were optimized, and pharmacokinetics were improved by engineering the variable region's charge properties. The BsAb was manufactured by selecting a shared light chain for the anti-FIXa and anti-FX heavy chains based on framework/complementarity-determining region shuffling and performing pI engineering to enhance ion exchange purification. Additionally, deamidation and solubility issues were resolved. The optimized BsAb demonstrated strong FVIII-mimetic activity in FVIII-absent plasma, a 3-week half-life, and high subcutaneous bioavailability in cynomolgus monkeys. Notably, the BsAb's activity was unaffected by FVIII inhibitors, enabling its use regardless of inhibitor presence. It can be produced at scale and formulated into a liquid formulation of 150 mg/mL for subcutaneous delivery, offering long-interval benefits for severe hemophilia A patients.

Fig.3 Schematic illustrations of FVIIIa mimetic BsAbs.³

Creative Biolabs offers customized design, engineering, manufacturing, and analysis services for various types of BsAbs. Our experienced and professional BsAb research team is confident in delivering high-quality BsAbs for protein mimics to meet our customers' needs.