LD343

LD343 is a proprietary, hydrophilic linker-payload platform developed by ProfoundBio for the construction of next-generation antibody-drug conjugates (ADCs). It consists of a highly hydrophilic, stable, protease-cleavable linker conjugated to monomethyl auristatin E (MMAE), a potent microtubule inhibitor. The platform is designed to mask the inherent hydrophobicity of the MMAE payload, enabling the development of ADCs with a high drug-to-antibody ratio (DAR) of 8 while maintaining favorable physicochemical and pharmacokinetic properties. By increasing the tolerated drug load and improving the therapeutic index, LD343 aims to enhance antitumor activity and safety compared to traditional vedotin-based ADCs. It is currently utilized in clinical-stage candidates such as PRO1107, a PTK7-targeted ADC.