Discovery and development of bispecific antibodies.

Bispecific antibodies (BsAbs) represent a significant breakthrough in antibody-based therapeutics, offering the unique capability to engage two distinct targets simultaneously. BsAbs are expected to exert therapeutic effects that are unattainable with conventional antibody drugs. Specifically, they are being developed for use in intercellular bridging, proximity effects, dual target inhibition, and cell targeting dependent on two antigen types. In recent years, antibody drug discovery has made progress by taking advantage of this dual-targeting ability, and bispecific antibodies have been launched across multiple therapeutic areas. These include antitumor drugs intended to enhance T-cell killing activity and inhibit growth factors, drugs that mimic blood coagulation factor functions, and angiogenesis inhibitors. This review highlights the pivotal technological advancements that have overcome the manufacturing challenges associated with BsAbs, enabling the development of pharmaceutical-grade products. We use emicizumab as a case study to illustrate these developments. Particular emphasis is placed on the critical synergy between antibody engineering technology and protein purification technologies, which has played a crucial role in the successful production of BsAbs. Furthermore, we discuss recent innovations in affinity chromatography, specifically the development of alkaline-resistant Protein L resins that have significantly improved commercial production processes. We examine the unique affinity behaviors of these resins and their impact on BsAb purification. This comprehensive review aims to provide researchers and industry professionals with a thorough understanding of the current landscape and future potential of bispecific antibodies in therapeutic applications, highlighting both technical challenges and innovative solutions in this rapidly evolving field.