TY - JOUR
T1 - An expanded genetic code facilitates antibody chemical conjugation involving the lambda light chain
AU - Kato, Akifumi
AU - Ohtake, Kazumasa
AU - Tanaka, Yoshitaka
AU - Yokoyama, Shigeyuki
AU - Sakamoto, Kensaku
AU - Shiraishi, Yasuhisa
N1 - Funding Information:
This work was supported by Kyowa Kirin Co., Ltd. and RIKEN.
Publisher Copyright:
© 2021 The Authors
PY - 2021/3/26
Y1 - 2021/3/26
N2 - Most of the currently approved therapeutic antibodies are of the immunoglobulin gamma (IgG) κ isotype, leaving a vast opportunity for the use of IgGλ in medical treatments. The incorporation of designer amino acids into antibodies enables efficient and precise manufacturing of antibody chemical conjugates. Useful conjugation sites have been explored in the constant domain of the human κ-light chain (LCκ), which is no more than 38% identical to its LCλ counterpart in amino acid sequence. In the present study, we used an expanded genetic code for site-specifically incorporating Nε-(o-azidobenzyloxycarbonyl)-L-lysine (o-Az-Z-Lys) into the antigen-binding fragment (Fab) of an IgGλ, cixutumumab. Ten sites in the LCλ constant domain were found to support efficient chemical conjugation exploiting the bio-orthogonal azido chemistry. Most of the identified positions are located in regions that differ between the two light chain isotypes, thus being specific to the λ isotype. Finally, o-Az-Z-Lys was incorporated into the Fab fragments of cixutumumab and trastuzumab to chemically combine them; the resulting bispecific Fab-dimers showed a strong antagonistic activity against a cancer cell line. The present results expand the utility of the chemical conjugation method to the whole spectrum of humanized antibodies, including the λ isotype.
AB - Most of the currently approved therapeutic antibodies are of the immunoglobulin gamma (IgG) κ isotype, leaving a vast opportunity for the use of IgGλ in medical treatments. The incorporation of designer amino acids into antibodies enables efficient and precise manufacturing of antibody chemical conjugates. Useful conjugation sites have been explored in the constant domain of the human κ-light chain (LCκ), which is no more than 38% identical to its LCλ counterpart in amino acid sequence. In the present study, we used an expanded genetic code for site-specifically incorporating Nε-(o-azidobenzyloxycarbonyl)-L-lysine (o-Az-Z-Lys) into the antigen-binding fragment (Fab) of an IgGλ, cixutumumab. Ten sites in the LCλ constant domain were found to support efficient chemical conjugation exploiting the bio-orthogonal azido chemistry. Most of the identified positions are located in regions that differ between the two light chain isotypes, thus being specific to the λ isotype. Finally, o-Az-Z-Lys was incorporated into the Fab fragments of cixutumumab and trastuzumab to chemically combine them; the resulting bispecific Fab-dimers showed a strong antagonistic activity against a cancer cell line. The present results expand the utility of the chemical conjugation method to the whole spectrum of humanized antibodies, including the λ isotype.
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U2 - 10.1016/j.bbrc.2021.02.005
DO - 10.1016/j.bbrc.2021.02.005
M3 - Article
C2 - 33561746
AN - SCOPUS:85100441743
VL - 546
SP - 35
EP - 39
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
ER -