Recent Chemical Approaches for Site‐Specific Conjugation of Native Antibodies: Technologies toward Next‐Generation Antibody–Drug Conjugates

Abstract

Antibody–drug conjugates (ADCs), which consist of three components, antibody, linker, and payload, can function as “magic bullets”. These conjugates offer the ability to target drug delivery to specific cells, based on cell‐specific recognition and the binding of an antigen by a monoclonal antibody (mAb). In particular, by delivering a cytotoxic payload to cancer cells, ADCs are expected to provide a breakthrough in oncology treatments by providing a way to increase efficacy and decrease toxicity, in comparison with traditional chemotherapeutic treatments. The development of ADC therapeutics has dramatically progressed in the past decade and two ADCs have been approved and used as anticancer drugs in the clinic. However, several critical issues regarding the performance of ADCs are still being discussed and investigated. Indeed, in the past few years, several groups have reported that, changing the number and position of the drug payloads in the ADCs, affects the pharmacokinetics, drug release rates, and biological activity. The use of conventional heterogeneous conjugation methods for ADC preparation results in the drug/antibody ratio and connecting position of the payload having stochastic distributions. Therefore, it is important to investigate how these potential problems can be circumvented through site‐specific conjugation. Herein, various site‐specific chemical conjugation strategies with native mAbs that are currently used for the production of ADCs, including residue‐selective labeling for generating ADCs, disulfide rebridging, and affinity‐peptide‐mediated site‐specific chemical conjugation technologies, are reviewed and described.

Antibody Conjugates-Recent Advances and Future Innovations

“…Alternatively, native antibodies can be conjugated site-specifically [84] after enzymatic modification of natural amino acids such as tyrosines [85] and glutamines [67], and carbohydrates can be oxidized chemically or modified with enzymes to produce reactive groups for conjugation [86][87][88]. For instance, sodium periodate oxidation of fucose at the native N-linked glycan of an antibody installed an aldehyde for conjugation with hydrazides [86].…”

DNAzymes for amine and peptide lysine acylation

“…25,26 One such reaction is lysine (Lys) acylation, where Lys acetylation is critical for histones and in other contexts, [27][28][29][30] and many longer-chain Lys acylation PTMs [31][32][33] such as malonylation, 34,35 succinylation, 34,36 and glutarylation 37,38 have been discovered yet are poorly understood. 39 As an alternative to approaches that include introduction of Lys analogues, [40][41][42][43] nonsense codon suppression, [44][45][46][47][48][49] bottom-up ligation-based assembly strategies, [50][51][52] or enzymatic methods that typically require creation of a non-native protein by insertion of a specific target sequence, [53][54][55][56][57][58] DNAzymes are promising for top-down introduction of Lys acylation PTMs onto intact native proteins, [59][60][61][62][63][64][65] but only if DNAzymes can be identified with the fundamental catalytic ability of Lys acylation.…”

Antibody–Drug Conjugates Using Mouse–Canine Chimeric Anti-Dog Podoplanin Antibody Exerts Antitumor Activity in a Mouse Xenograft Model

“…However, to overcome difficulties involved in controlling the modification site and the drug concentration (drug-to-antibody ratio [DAR]), site-specific modification of the antibody has been favored. (2) Recently, chemical conjugation by affinity peptide (CCAP) has been developed using affinity peptide to the antibody Fc fragment as a novel site-specific conjugation system. (3) Utilizing CCAP, various kinds of therapeutic molecules, from low molecular weight compounds to proteins, can be attached to the antibody Fc through the affinity peptide.…”