The relevance of the work was validated in terms of ADC homogeneity (HIC-HPLC, MS), purity (SEC-HPLC), isolated antigen recognition (ELISA) and biological activity (HER2-positive breast cancer cells cytotoxicity assays)

The relevance of the work was validated in terms of ADC homogeneity (HIC-HPLC, MS), purity (SEC-HPLC), isolated antigen recognition (ELISA) and biological activity (HER2-positive breast cancer cells cytotoxicity assays). KEYWORDS:ADC, mAb, trastuzumab, assembly, disulfide bonds, Cys-based conjugation, homogeneous conjugation, affinity chromatography, cancer == Introduction == Antibody-drug conjugates (ADCs) are a class of targeted therapy used in the treatment of various cancers. using trastuzumab as a model. The method is based on the production of heavy chains (HC) and light chains (LC) in two recombinant HEK293 impartial cultures, so the original amino acid sequence is not altered. Isolated LC was effectively conjugated to a single drug-linker (vcMMAE) construct and mixed to isolated HC dimers, in order to obtain a correctly folded ADC. The relevance of the work was validated in terms of ADC homogeneity (HIC-HPLC, MS), purity (SEC-HPLC), isolated antigen recognition (ELISA) and biological activity (HER2-positive breast cancer cells cytotoxicity assays). KEYWORDS:ADC, mAb, trastuzumab, assembly, disulfide bonds, Cys-based conjugation, homogeneous conjugation, affinity chromatography, cancer == Introduction == Antibody-drug conjugates (ADCs) are a class of targeted therapy used in the treatment of various cancers. As of late 2019, the US Food and Drug Administration (FDA) has approved four ADCs, three ADCs are undergoing regulatory review, and over 100 ADCs are in the clinical pipeline.1Their medical potential is based on their Glucagon-Like Peptide 1 (7-36) Amide structure, since it combines the ability of a monoclonal antibody (mAb) to specifically target a tumor-associated antigen2with the cell-killing ability of potent cytotoxic drugs via a chemical linker. These unique targeted drugs, however, pose both technological and developmental challenges. One key characteristic of an ADC is the drug:antibody ratio (DAR), which is the number of cytotoxic drug molecules per molecule of antibody. The DAR defines the two major types of ADCs: heterogeneous (conjugated in random positions that vary between mAbs) and homogeneous (conjugation at specific sites that are defined in each mAb molecule). The four commercially available ADCs are heterogeneous due to limitations in the technology available when they were originally developed. The lack of efficient methods for producing completely homogeneous ADCs has Rabbit Polyclonal to Gz-alpha compelled pharmaceutical companies to develop site-specific conjugation methods, which improves ADC homogeneity,3batch-to-batch consistency, and is more desirable from a regulatory perspective.4 Different approaches have been developed to obtain homogeneous ADCs by site-specific conjugation, including cysteine residue(s) addition, non-natural amino acids, enzyme-mediated conjugation (including transglutaminase, sortase Glucagon-Like Peptide 1 (7-36) Amide A, glycosyltransferase or endoglycosidase) and linker-based conjugation.5-12 Cysteine-engineered residues have been introduced into different antibodies by site-directed mutation to provide free thiol groups for conjugation using conventional thiol-specific Glucagon-Like Peptide 1 (7-36) Amide maleimide linkers,13a technology developed by Seattle Genetics and used to produce the heterogeneous ADC brentuximab vedotin (Adcetris), which was approved by FDA in 2011. The process generates almost homogeneous ADCs made up of approximately two drug molecules per antibody, but additional antibody reduction/oxidation actions are required for selective conjugation of the added cysteines.14-16 Non-recombinant methods for reducing ADC heterogeneity that enable the production of homogeneous ADCs based on existing antibodies have also been developed. For example, disubstituted maleimide linkers have been used for synthesizing homogeneous ADCs via interchain cysteine cross-linking through disulfide bonds rebridging.17Godwin and coworkers presented an alternative thiol conjugation approach where bis-sulfone-functionalized reagents are used to form a stable three-carbon bridge with disulfides.18In addition, the structure of the antibody remains intact and the ligand-to-antibody ratio can be tightly controlled, with a 78% conversion to DAR 4 ADCs.19Badescu and coworkers used a bis-sulfone linker designed Glucagon-Like Peptide 1 (7-36) Amide to react with two antibody cysteines to conjugate an auristatin payload (monomethyl auristatin E (MMAE)) to trastuzumab and its antigen-binding fragments (Fabs).20The approaches described above are time consuming and specific for each construct, as they often require extensive antibody engineering to identify the optimal conjugation sites9,21where unique side chains can be introduced for conjugation, or they require complex linker and payload modifications that have not been clinically validated. 8As a result, they are not suitable for converting existing antibodies directly into ADCs.5,7 In vivo, heavy chains (HCs) and light chains (LCs) are.