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ADC drug site-specific conjugation technology

As a new type of targeted anticancer drug, ADC has huge market prospects and development space. Although ADC drugs also have toxicity risks in anti-tumor, with the development of engineered antibodies, the continuous optimization of linkers, the discovery of high active loads and the continuous improvement of conjugation technology, new ADC drugs with high efficiency and low toxicity will continue to emerge. .

Commonly used site-directed coupling technologies: introduction of reactive cysteine, engineered mutant unnatural amino acid coupling technology, glycosyl coupling technology, amino-directed coupling technology of specific lysine, polypeptide enzymatic coupling technology, etc.

With the continuous updating of technology, site-specific conjugation technology can generate homogeneous ADC drugs, further increasing the therapeutic window. These controllable linking strategies mainly include: Thiomab site-directed coupling, unnatural amino acid site-directed coupling and various enzyme-catalyzed site-directed coupling.

Thiomab site-specific conjugation

Thiomab technology, first developed by Genentech. The principle is to introduce reactive cysteine.

Through genetic engineering, cysteine ​​residues are inserted at specific points of the antibody, and then the sulfhydryl (-SH) of cysteine ​​is coupled to the toxin to form a site-specific antibody-drug conjugate.

The ADC drug-antibody ratio conjugated by this method is uniform, and 92.1% of the products have a DAR of 2. This site-directed conjugation neither interferes with immunoglobulin folding and assembly nor alters the binding mode of antibody and antigen. The ADC drug using Thiomab antibody improves tolerance and reduces systemic toxicity while retaining in vivo antitumor activity.

In addition to Genentech, Seagen’s MAIA technology is based on a similar principle.

Thiomab Technology Unnatural Amino Acid Antibody Conjugation

Unnatural amino acids provide a new technical means for the development of ADCs. Antibody-drug site-specific conjugation can be achieved through unnatural amino acids. That is, unnatural amino acids are introduced into specific sites of any target protein in the organism. Residues on these unnatural amino acids can be combined with linkers to form site-specific ADCs.

Compared with traditional ADC drugs, antibodies and drug linkers introduced with unnatural amino acids can achieve site-specific and quantitative coupling, and the obtained ADC has high efficacy, good stability, high safety, and uniform drug-to-resistance ratio (DAR). There are also disadvantages such as difficulty in antibody expression and easy generation of immunogenicity.

Three steps

– In vitro synthesis of unnatural amino acids that meet the needs of finished medicines by medicinal chemistry methods;
-Unnatural amino acids are tightly linked with special tRNAs under the action of tRNA (transfer RNA) synthases and transported to the ribosomes where proteins are synthesized;
– In the ribosome, tRNA recognizes special codons at specified positions and precisely inserts unnatural amino acids into specific parts of the polypeptide chain.

The non-natural amino acid antibody conjugation technology, like other site-specific conjugation technologies, essentially solves various problems caused by random conjugation technology, such as product batch inhomogeneity, poor stability, and potential toxicity.

The most complex and most important work in the antibody coupling technology of unnatural amino acids is in the preparation stage of the antibody, that is, how to insert the unnatural amino acid into the antibody. Unnatural, that is, amino acids that are not found in animals and plants; solve the problem of how to encode, transport, and insert unnatural amino acids carrying various functional groups (coupling sites).

Axispharm conjugation service delivers affordable and high quality custom ADC conjugation service, using combinations of payloads, linkers, and conjugation methods. Service includes a comprehensive ADC report with full characterizing specifications.

Protein-drug Conjugation
Fluorophore Conjugation
Biotin conjugation
Antibody-drug conjugate (ADC)
Polymer–drug conjugation
Polymer-drug-target ligand conjugation
Cysteine-based conjugation
Lysine-based conjugation
Thio-engineered antibody
Carbohydrate-based conjugation
Unnatural amino acids-based conjugation