With broad experience in antibody engineering, Creative Biolabs now provides thio-engineered antibodies for site-special conjugation in ADC development. We can perform different conjugation methods to create ADCs to meet every client’s individual requirement.
Figure: Thio-engineered Antibody conjugation and its DAR (Abhijit S. Bhat. 2014)
In ADCs, function groups such as cytotoxic drugs are conjugated to antibodies either through lysine amino groups or cysteine sulfhydryl groups, which are conventional conjugation methods. The conjugation technology employs solvent-accessible lysine residues exposed at the surface of antibodies to react with activated esters to generate stable amide or amidine bonds. while cysteine-based conjugation is done by conjugating the reduced cysteine groups of an antibody to maleimide-containing linkers. Both lysine and cysteine based conjugation produce heterogeneous ADC species with different CAR and linkage sites. In order to increase the site specificity of conjugation and create more homogeneous ADCs, antibodies with engineered cysteines are developed, named Thio-engineered Antibodies. In this method, the first step is to introduce site-directed mutagenesis by PCR. Thio-engineered Antibodies enable thiol-conjugation with thiol-reactive linkers at specific sites, which permits the resulting ADCs have uniform distribution and superior safety. After conjugation of the modified antibody with drugs, hydrophobic interaction chromatography (HIC) and mass spectrometric (LC–MS) analysis can be used to quantitate the number of drugs per antibody and cell-based assay to assess the engineered ADCs binding and potency. Using optimized process conditions, ADCs conjugated through Thio-engineered Antibodies can achieve 92% DAR=2 and conversions over 98%. This efﬁciency makes this technology more amenable to industrial-scale production. Up to the present, Thio-engineered Antibodies have been successfully used to conjugate cytotoxic drugs, biotin, fluorophore or radiolabels for scientific and clinical researches.
As a global biotech company, Creative Biolabs can provide custom services of ADCs using diverse conjugation methods. Scientists from Creative Biolabs can assist clients design and perform the most appropriate strategy for ADC development.