Hydrophilic Sequence-Defined Cross-Linkers for Antibody–Drug Conjugates

Abstract

Antibody−drug conjugates (ADCs) are an established modality for the tissue-specific delivery of chemotherapeutics. However, due to the hydrophobic nature of many cytotoxic payloads, challenges remain in developing chemically stable ADCs with high drug loading. In previous studies, payload structure, unique stimuli-responsive chemistries, and PEGylated cross-linkers have been used to decrease ADC hydrophobicity. In this work, we investigate the effect of a new parameter, cross-linker sequence. A support-free synthesis of PEGylated, sequence-defined cross-linkers was developed and applied to the synthesis of three constitutionally isomeric ADCs containing PEG side chains and a monomethyl auristatin E payload. Placement of PEG side chains distally from the payload was found to yield an ADC with altered hydrophilicity, antigen binding, and in vitro potency. This work establishes a versatile method for synthesizing multifunctional cross-linkers and identifies cross-linker sequence as a new handle for modulating the performance of ADCs.

Antibody–drug conjugates: Recent advances in linker chemistry

“…Therefore, the hydrophilicity of ADCs is crucial. Currently, strategies for improving the hydrophilicity of ADCs are mainly divided into two categories: (1) incorporating PEG or sulfonate moieties into the linker of the ADC 86 , 87 , 88 , 89 ; or (2) developing highly hydrophilic linkers, such as phosphate-based linkers or charged linkers like [ethylene diamine platinum II] 2+ linkers mentioned at the beginning of this review. In addition to linker hydrophilicity affecting the plasma kinetics and off-target toxicity of ADCs, a series of studies by Zhang et al .…”

Sequence-Defined Synthetic Polymers for New-Generation Functional Biomaterials

“…It is worth mentioning that the pharmacokinetics and tolerability of ADCs are greatly affected by drug-to-antibody ratios (DARs) of the conjugates, with typical values of 2–4, whereas a higher DAR commonly increases the overall hydrophobicity of ADCs, compromising their therapeutic efficacy . To resolve this issue, hydrophilic homopolymers have been attempted to construct homogeneous ADCs with defined sequence or high DARs. , Specifically, discrete polysarcosine-based linkers as hydrophobicity masking motifs were synthesized to formulate β-glucuronidase-sensitive ADCs with a DAR of 8 (Figure b) . Chain-length-dependent pharmacokinetic properties and in vivo antitumor activities were further investigated, revealing an optimal length of polysarcosines (i.e., dodecamer).…”

Diazido macrocyclic sulfates as a platform for the synthesis of sequence-defined polymers for antibody drug conjugates

“…A number of innovative strategies have been employed in the synthesis of chemically-dened polymers including: Passerini reactions, 15 esterication/amidation reactions, [16][17][18] click reactions, [19][20][21] photochemical transformations, 22 radical reactions, 23,24 and many more. 25 Furthermore, a portion of these chemistries have been employed directly as linkers for ADCs with step-growth polysarcosines 18 and oligothioetheramide backbones 20,26 demonstrating the added benet of sequence-dened polymers in the ADC eld.…”