Utilization of Neutrophil Elastase Tetrapeptide Substrate as a Linker Agent for Anti-GD2 Antibody Drug Conjugates

Disialoganglioside GD2 (GD2) is highly expressed in several tumors. While anti-GD2 antibodies and GD2-based antibody-drug conjugates (ADCs) have shown some therapeutic efficacy, their activity requires enhancement. Elastase, abundant in tumor microenvironment, has substrates that can serve as ADC linkers. Here, we constructed an anti-GD2 ADC by conjugating the anti-GD2 antibody Hu3F8 to the payload monomethyl auristatin E (MMAE) via an elastase-cleavable tetrapeptide linker (BMOA). Hu3F8 was produced using a 293F expression system, and its specific binding to GD2-positive cells was confirmed. The cytotoxicity of the ADCs was evaluated in both GD2-positive and GD2-negative tumor cell lines with or without elastase and its antitumor effects were investigated. It showed GD2-dependent cytotoxicity, with a significantly decreased IC₅₀ in GD2-positive cells upon elastase addition, while no cytotoxicity was observed in GD2-negative cells. Additionally, Hu3F8-BMOA-MMAE induced significant cell cycle arrest and apoptosis in GD2-positive cells, with stronger effects in the presence of elastase. In M21 melanoma mouse models, Hu3F8-BMOA-MMAE achieved an obvious tumor inhibition rate compared to the control. These findings demonstrate that utilizing a neutrophil elastase tetrapeptide substrate as a linker in anti-GD2 ADCs is a potential strategy for the therapy of GD2-positive tumors.