Antibody–bottlebrush prodrug conjugates for targeted cancer therapy

Antibody–drug conjugates (ADCs) are effective targeted therapeutics but are limited in their ability to incorporate less-potent payloads, varied drug mechanisms of action, different drug release mechanisms and tunable drug-to-antibody ratios. Here we introduce a technology to overcome these limitations called ‘antibody–bottlebrush prodrug conjugates’ (ABCs). An ABC consists of an IgG1 monoclonal antibody covalently conjugated to the terminus of a compact bivalent bottlebrush prodrug that has payloads bound through cleavable linkers and polyethylene glycol branches. This design enables the synthesis of ABCs with tunable average drug-to-antibody ratios up to two orders of magnitude greater than those of traditional ADCs. We demonstrate the functional flexibility and manufacturing efficiency of this technology by synthesizing more than 10 different ABCs targeting either HER2 or MUC1 using drugs with potencies spanning several orders of magnitude as well as imaging agents for ABC visualization and photocatalysts for proximity-based labeling of the ABC interactome. ABCs display high target engagement, high cell uptake and improved efficacy in tumor models compared to conventional HER2-targeted ADCs, suggesting promise for clinical translation.