Synergistically-enhanced Polyethylene Glycolated Dipeptide Linkers for Construction of Antibody-drug Conjugates with Stable and High Drug-loading

OBJECTIVE To rationally design a novel linker for constructing an antibody-drug conjugate(ADC) with a high drug-to-antibody ratio(DAR) and excellent stability.

METHODS A new ADC drug, DS001, was designed and synthesized. By rationally constructing a polyethylene glycol(PEG)-modified valine-lysine(VK) linkerVK-(mPEG24)-PAB, eight monomethyl auristatin E(MMAE) molecules were precisely conjugated to the anti-Trop2 antibody hRS7 via site-specific conjugation technology, yielding a homogeneous conjugate with a DAR of 8, designated as DS001hRS7-VK-(mPEG24)-PAB-MMAE.

RESULTS In vitro experiments demonstrated that DS001 maintained high binding affinity to the Trop2 antigen and exhibited potent and specific cytotoxicity, with a half-maximal inhibitory concentration(IC₅₀) in the nanomolar range. Additionally, DS001 showed significantly extended stability in plasma. The optimized linker effectively mitigated hydrophobicity-driven aggregation, enabling the stable construction of an ADC with DAR 8.

CONCLUSION The PEGylated VK linker strategy developed in this study effectively addresses the common challenges of aggregation and instability in high-drug-load ADCs. DS001 retains potent antitumor activity while demonstrating favorable pharmacokinetic properties.