Although used for bulk capture and high-resolution binding of antibody products, the method can be challenging with bispecific antibodies because of the multiplicity of structures. The common method for purifying monoclonal antibodies (MAbs) and BsAbs following harvest and clarification uses affinity capture with a commercially available protein A resin. The predominant active form is a heterodimer (BsAb CD3-TAA) however, numerous inactive forms consisting of CD3 and TAA homodimers, half-antibodies, and excess light chains can contaminate expressed product. Figure 1 illustrates the variants of bispecific antibody CD3-TAA–expressed products. It brings an inherent potential to form inactive product variants that copurify with active products. The main challenge of producing bispecific antibodies comes with their heterogenous nature. The number of bispecific antibodies in clinical testing is growing rapidly ( 7), and so is the need for efficient production and purification strategies. It relies on noncovalent interactions, the result of complementary mutations in the CH3 domains ( 5) and hinge-region disulfide bonds, to form heterodimers ( 6). Correct pairing of heavy chains is achieved through knobs-into-holes technology. The human kappa light chain is bound to the full-length heavy chain. One heavy chain is full length (OmniFlic derived) and the other - discovered in UniRat transgenic rats ( 4) - is truncated, lacking the CH1 domain. The lead molecules are composed of three chains: two nonidentical human heavy chains and a human kappa light chain. Using proprietary UniRat human heavy-chain technology combined with OmniFlic human fixed–light-chain antibody technology licensed from Ligand Pharmaceuticals, Teneobio has produced several bispecific antibodies, each targeting a different tumor antigen and CD3 ( 3). Such BsAbs mediate cell killing by binding simultaneously to an antigen that is overexpressed on tumor cells and to the CD3 receptor, activating cytotoxic T lymphocytes ( 2). Note that only the full-length anti-CD3 human heavy chain has a CH1 domain, and the anti-CD3 human heavy chain is present in only two forms: the CD3-TAA heterodimer and CD3 homodimer.īispecific antibodies (BsAbs) are designed to recognize and bind two different antigens, in many cases for the purpose of immune effector-cell activation to destroy cancer cells ( 1). Aggregated forms of product also are present. Other forms include the TAA homodimer, CD3 homodimer, half-antibody, and L chain, all of which are inactive. When working with sensitive MAbs, the wide window of operation simplifies optimization of conditions.Figure 1: Variant forms of BsAb CD3-TAA–expressed products the CD3-TAA heterodimer (containing one light (L) and two heavy (H) chains) is the active form. ![]() The wide window of operation for conductivity and/or pH simplifies the process as conditioning after the protein A step can be omitted. Suitable for sensitive MAbs and other biomoleculesĬapto MMC ImpRes can be used for initial or final polishing steps in MAb purification processes, as well as for the polishing of antibody fragments such as domain antibodies (DAbs). ![]() The multimodal cation exchanger ligand of Capto MMC ImpRes is immobilized to the base matrix and interacts with the target molecule through multiple types of interactions. The weak cation exchange multimodal ligand enables high selectivity in a broad pH/salt window compared with traditional ion exchangers, which allows the use of Capto MMC ImpRes in a variety of process conditions to solve challenging purification problems. Suitable for polishing of antibody fragments.Displays a broad pH/salt operational window.Enables use of a platform approach to MAb process development.Efficient removal of aggregates, viruses, and main contaminants in MAb processes.
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