CovIsoLink?: New Bacterial Transglutaminase Q-Tag Substrate for the Development of Site Specific Antibody Drug Conjugates

摘要

CovIsoLink? is enzymatic, microbial transglutaminase mediated site-specific conjugation method for the generation of homogenous immunoconjugates. Our aim is to optimize ADC design and validate the improved therapeutic value of our technology compared to ADCs already available in the clinic. Using an in house peptide library we identified novel glutamine donor substrates (Q-tag) with improved affinity compared with the known peptides (ZQG, LLQG). As a proof-of-concept, we compared our CovIsolink immunoconjugates with Kadcyla? (targeting HER2). Different recombinant antibody formats (mAb, Fab, scFv) carrying the Q-tag sequences engineered into the C-terminal were developed and characterized. Furthermore the C-terminal sequence of mAb was optimized to avoid dimerization and polymerization. The conjugation of potent therapeutic compounds (MMAE, DM1, DM4) was accomplished, resulted on superior yield of conjugation with an average DAR of 1.75. In vitro and In vivo characterization and dose response studies of CovIsolink-ADCs specificity and reactivity were performed in Her2 positive models by comparison with Kadcyla (T-DM1).