A coiled coil-based pre-targeting drug delivery system for precise treatment of breast cancer

Background

Antibody-drug conjugates (ADCs) consist of an antibody linked to a cytotoxic agent. To optimize the efficacy of ADCs, our study developed a pre-targeting drug delivery system based on the specific interaction between two synthetic coiled-coil proteins, Zip1 and Zip2. The targeting vehicle was composed of Zip2-fused single-chain variable fragments, while the toxic vehicle consisted of Zip1 conjugated to cytotoxic agent monomethyl auristatin E via SNAP-tag.

Methods

The targeting activities of the pre-targeting reagents were evaluated using various techniques, including flow cytometry, fluorescence microscopy, cell viability and apoptosis assays, and ex vivo multiplex immunofluorescence.

Results

The pre-targeting complexes demonstrated specific binding and internalization in breast cancer cell lines, as assessed by flow cytometry and fluorescence microscopy. Furthermore, cell death was observed in antigen-expressing cell lines upon triggering apoptosis at nanomolar concentrations.

Conclusions

Given the heterogeneous tumor environment and individual differences, separating the “targeting” and “killing” steps enables targeting molecules to bind to different antigens, followed by the application of the Zip1-drug complex without requiring antibody engineering. Our study highlights the potential of this pre-targeting system to efficiently deliver drugs, offering a promising strategy to address challenges faced by ADCs, such as poor tissue penetration, low accumulation, and “on-target, off-tumor” toxicity.