Programmable Circular Multivalent Nanobody‐Targeting Chimeras (mNbTACs) for Multireceptor‐Mediated Protein Degradation and Targeted Drug Delivery

Multispecific therapeutics hold significant promise in drug delivery, protein degradation, and cell recruitment to address clinical issues of tumor heterogeneity, resistance, and immune evasion. However, their modular engineering remains challenging. We developed a targeted degradation platform, termed multivalent nanobody‐targeting chimeras (mNbTACs), by encoding diverse nanobody codons on a circular template using DNA printing technology. The homo‐ or hetero‐ mNbTACs specifically recognized membrane targets in a multivalent manner and simultaneously recruited scavenger receptors to favor clathrin‐/caveolae‐dependent endocytosis and lysosomal degradation of multiple proteins with high efficiency and selectivity. We demonstrated that a bispecific doxorubicin‐loaded mNbTAC, named Doxo‐mvNbsPPH, passively accumulated at tumor sites, specifically interacted with PD‐L1 and HER2 targets, and was rapidly transported into lysosome, inducing potent immunogenic cell death and alleviating immune checkpoint evasion. The synergistic boosting of innate and adaptive immunity promoted the infiltration and proliferation of CD8+ T cells in tumor microenvironment (an 11‐fold increase) with high toxicity and low exhaustion, eventually enhancing antitumor efficacy. Our mNbTAC platform provides multispecific therapeutics with variable valences and programmed species, whereas it induces targeted protein degradation through multireceptor‐mediated endocytosis and lysosomal degradation without the need for lysosome‐targeting receptors, representing a general and modular tool to harness extracellular proteome for disease treatment.