Hijacking Extracellular Targeted Protein Degrader–Drug Conjugates for Enhanced Drug Delivery

Antibody-based therapeutics encompass diverse modalities for targeting tumor cells. Among these, antibody-drug conjugates (ADCs) and extracellular targeted protein degradation (eTPD) specifically depend on efficient lysosomal trafficking for activity. A major limitation of ADCs is their reliance on antigens with efficient internalization, while eTPD approaches, although capable of trafficking diverse targets to lysosomes, lack cytotoxic potency. To address this, we developed degrader-drug conjugates (DDCs), leveraging the endocytic and recycling activities of eTPD to enhance lysosomal delivery. We utilized fast internalizers, the low-density lipoprotein receptor (LDLR) and the chemokine receptor (CXCR7), to enhance lysosomal delivery. LDLR-based degraders enabled efficient and selective degradation of diverse extracellular membrane proteins, while DDCs with cytotoxic payload enhanced cytotoxicity compared to conventional ADCs <i>in vitro</i>. This dual modality addresses key challenges of inadequate internalization in conventional ADCs and cytotoxic potency in current eTPD strategies. Our findings demonstrate that DDCs provide additional optionality for developing next-generation antibody therapeutics with broader utility and improved efficacy in cancer treatment.