posted on 2022-03-23, 20:06authored byTaeJin Lee, Ju Hwan Kim, Se Jeong Kwon, Jin Woo Seo, Sun Hee Park, Jinyoung Kim, Jonghwa Jin, Ji Hye Hong, Hyo Jin Kang, Chiranjeev Sharma, Ji Hoon Choi, Sang J. Chung
Immunoglobulin
Gs (IgGs) contain many Lys and Cys residues, which
results in an unwanted complex product mixture with conventional drug
conjugation methods. We selectively acylated the ε-NH2 of K248 on trastuzumab using an IgG Fc-binding peptide (FcBP) equipped
with a 5-norbornene-2-carboxylic acid thioester (AbClick-1). AbClick-1
locates its thioester close to the ε-NH2 of K248
while binding to trastuzumab. Consequently, the thioester underwent
proximity-driven selective acylation of ε-NH2 through
an S to N acyl transfer reaction.
Furthermore, N-tert-butyl maleimide
accelerated the cross-linking reaction with an approximately 95% yield
of the desired product by scavenging the byproduct (FcBP-SH). Only
K248 was modified selectively with the 5-norbornene-2-carbonyl group,
which was further modified by click reaction to afford an antibody–drug
conjugate (ADC) with two drugs per antibody. The resulting ADCs showed
remarkable in vitro and in vivo anticancer
activity. Our results demonstrate that a thioester is a promising
chemical entity for proximity-driven site-selective conjugation of
antibodies.