Generation of therapeutic immunoconjugates via Residue-Specific Conjugation Technology (RESPECT) utilizing a native cysteine in the light chain framework of Oryctolagus cuniculus.

Generation of therapeutic immunoconjugates via Residue-Specific Conjugation Technology (RESPECT) utilizing a native cysteine in the light chain framework of Oryctolagus cuniculus.

Cancer Biol Ther. 2017 Apr 10;:0

Authors: Albone EF, Spidel JL, Cheng X, Park YC, Jacob S, Milinichik AZ, Vassen B, Butler J, Kline JB, Grasso L

Abstract
The conjugation of toxins, dyes, peptides, or proteins to monoclonal antibodies is often performed via free thiol groups generated by either partial reduction methods or engineering free cysteine residues into the antibody sequence. Antibodies from the rabbit Oryctolagus cuniculus have an additional intrachain disulfide bond, whereby the light chain variable kappa domain is bridged to the constant kappa region between cysteine residues at positions 80 and 171, respectively. Chimerization of rabbit antibodies with human constant domains allows for the generation of a free thiol group at the light chain position 80 (C80) that can be utilized for site-specific conjugation. An efficient process for the purification and simultaneous removal of cysteinylation at the C80 site was developed. The unpaired C80 was shown to be efficiently conjugated using a number of different maleimido-based ligands. REsidue SPEcific Conjugation Technology (RESPECT) antibody-drug conjugates prepared using rabbit-human chimeric anti-human mesothelin rabbit antibodies and maleimido-PEG2-auristatin conjugated to C80 were shown to be highly potent and specific in vitro and effective in vivo in reduction of tumor growth in a highly aggressive mesothelin-expressing xenograft tumor model.

PMID: 28394698 [PubMed - as supplied by publisher]

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