ADCs combine the high specificity of monoclonal antibodies with the high activity of small molecule cytotoxic drugs to improve the targeting of tumor drugs. CD BioGlyco has extensive experience to fit the specific needs of clients in the development of glycosylation site-specific ADCs.

The Development History of ADC

ADC is a drug that combines the high specificity of monoclonal antibodies with the high activity of small molecule cytotoxic drugs to improve the targeting of tumor drugs and reduce toxic side effects. At present, the development of ADCs has gone through three stages: 1) The first-generation ADCs use mouse-derived antibodies or chimeric antibodies and use non-site-directed conjugation technology, resulting in poor efficacy, strong toxic side effects, strong immunogenicity, and short half-life; 2) The second-generation ADC is improved based on the first-generation ADC and monoclonal antibodies with better antigen affinity are selected to improve the targeting of tumor cells and reduce cross-reaction with normal tissues. Second-generation ADCs have higher targeting, higher efficacy, and lower immunogenicity. However, there are still problems such as strong toxic side effects, drug resistance, and high drug-to-antibody ratio (DAR); 3) The third-generation ADC uses small molecule toxicants and human monoclonal antibodies for site-specific coupling, and the DAR value is more uniform. And there are many differentiated small molecule poisons to choose from. Compared to the previous two generations of ADCs, the stability and pharmacokinetics are greatly improved, the drug activity is higher, and the toxicity is lower.

Glycan Enzymatic Modification-based ADC Development Services

The third-generation ADC mainly focuses on selecting unique amino acid sites and using unique molecules or performing site-specific coupling through proximity effect, mainly including the following 4 types: 1) Interchain disulfide bond modification; 2) Glycosylation site-specific conjugation; 3) Chemoselective modification; 4) Proximity-based modification. At CD BioGlyco, we provide ADC development services based on the enzymatic modification of glycans for our clients. The specific strategies are as follows:

• Treatment of antibody glycans by β1,4-galactosyltransferase (β1,4-GalT) and α2,6-sialyltransferase (α2,6-SiaT) yields products with monosialylated glycans. These glycans are then oxidized by periodate and conjugated to aminooxy drugs.

Fig.1 Enzymatic transfer of galactose and sialic acid-based site-specific conjugation. (Agarwal & Bertozzi, 2015)

• To eliminate the need for periodate treatment, an azide-modified sialic acid derivative at the C9 position is incorporated into antibody N-glycans, using the substrate tolerance of sialyltransferases. The cyclooctyne-conjugated biotin, fluorophore, or cytotoxic drug is then reacted with the azide-containing antibody to form ADC with DARs of 3.5-4.5.

Fig.2 Enzymatic transfer of galactose and 9-azidosialic acid-based site-specific conjugation. (Agarwal & Bertozzi, 2015)

• Transfer of N-azidoacetylgalactosamine (GalNAz) to substrates containing N-acetylgalactosamine (GalNAc) by β1,4-GalT mutants. The modified antibody is then attached to the payload via copper-free click chemistry, resulting in a highly stable and homogeneous ADC.

Fig.3 Enzymatic removal of terminal galactose-based site-specific conjugation. (Agarwal & Bertozzi, 2015)

Advantages of Us

• Glycosylation site-specific conjugation
• Three enzymatic strategies
• Customized development solutions
• Professional development team

CD BioGlyco is committed to providing ADC development services utilizing glycosylation site-specific conjugation technology to meet the research needs of our clients. If you have glycan enzymatic modification-based ADC development services, please feel free to contact us for more information.

Reference:

1. Agarwal, P.; Bertozzi, C.R. Site-specific antibody-drug conjugates: the nexus of bioorthogonal chemistry, protein engineering, and drug development. Bioconjugate chemistry. 2015, 26(2): 176-192.