Efficient production of bispecific antibody by FAST-Ig^TM and its application to NXT007 for the treatment of hemophilia A

ABSTRACT

Efficient production of bispecific antibodies (BsAbs) in single mammalian cells is essential for basic research and industrial manufacturing. However, preventing unwanted pairing of heavy chains (HCs) and light chains (LCs) is a challenging task. To address this, we created an engineering technology for preferential cognate HC/LC and HC/HC paring called FAST-Ig (Four-chain Assembly by electrostatic Steering Technology – Immunoglobulin), and applied it to NXT007, a BsAb for the treatment of hemophilia A. We introduced charged amino-acid substitutions at the HC/LC interface to facilitate the proper assembly for manufacturing a standard IgG-type BsAb. We generated CH1/CL interface-engineered antibody variants that achieved > 95% correct HC/LC pairing efficiency with favorable pharmacological properties and developability. Among these, we selected a design (C3) that allowed us to separate the mis-paired species with an unintended pharmacological profile using ion-exchange chromatography. Crystal structure analysis demonstrated that the C3 design did not affect the overall structure of both Fabs. To determine the final design for HCs-heterodimerization, we compared the stability of charge-based and knobs into hole-based Fc formats in acidic conditions and selected the more stable charge-based format. FAST-Ig was also applicable to stable CHO cell lines for industrial production and demonstrated robust chain pairing with different subclasses of parent BsAbs. Thus, it can be applied to a wide variety of BsAbs both preclinically and clinically.

KEYWORDS:

• ART-S3
• bispecific antibody
• CHO cell line
• emicizumab
• FAST-Ig
• Hemophilia A
• KiH
• NXT007
• Orthogonal Fab
• single-cell production

Acknowledgments

We thank our colleagues at Chugai Pharmaceutical Co., Ltd. and Chugai Research Institute for Medical Science, Inc. We thank Ryota Kitada for assisting with the CIEX analysis of a large number of samples and Haruna Shinba for constructing plasmids and confirming their quality. We thank Shiho Ohtsu for analyzing physicochemical properties and Noyuri Imai for the SPR analysis. We thank Miho Mamiyoda and Shotaro Watanabe for providing mixtures of the plasmids used in transfections. We thank Yui Kaneta for assisting with the development of the stable CHO cell line. We thank Jacob Davis for English language editing. This work was fully supported by Chugai Pharmaceutical Co. Ltd.

Disclosure statement

All the authors are current employees of Chugai Pharmaceutical Co., Ltd. TI and TK are named as inventors of the patent, “Antigen-binding molecule having regulated conjugation between heavy-chain and light-chain” (WO/2013/065708). HK, KY, YT, and TI are inventors of the patent, “Multispecific antigen-binding molecule having blood coagulation factor VIII (FVIII) cofactor function-substituting activity, and pharmaceutical formulation containing said molecule as active ingredient” (WO/2019/065795). FAST-Ig is a trademark of Chugai Pharmaceutical Co., Ltd. These facts do not alter the authors’ adherence to all the mAbs policies on sharing data and materials.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19420862.2023.2222441

Additional information

Funding

This work was fully supported by Chugai Pharmaceutical Co., Ltd. Funding to pay the Open Access publication charges for this article was provided by Chugai Pharmaceutical Co., Ltd.