These findings establish TROP2 as a robust LTR and provide a versatile eTPD platform with profound translational potential for tumor treatment, as well as design TRTAC-drug conjugates, enabling targeted protein degradation together with enhanced drug delivery.
Abstract
Extracellular targeted protein degradation (eTPD) systems typically utilize lysosome-targeting receptors (LTRs) to mediate internalization and lysosomal degradation of extracellular and membrane proteins. While multiple LTRs have been discovered, there remains a compelling need to seek for new LTRs, particularly those with clear clinical relevance, to expand the therapeutic potential of eTPD. Here we report trophoblast cell surface antigen-2 (TROP2), a clinically validated tumor-associated antigen, as a promising tumor-selective LTR. We engineer TROP2-targeting chimeras (TRTACs) by genetically fusing a TROP2-binding nanobody to nanobodies against specific target proteins. We show that TRTACs can induce tumor cell-selective degradation of diverse membrane proteins, including epithelial growth factor receptor (EGFR), human epithelial growth factor receptor 2 (HER2), and programmed death-ligand 1 (PD-L1). The EGFR-targeted TRTAC significantly inhibits tumor cell proliferation and shows potent antitumor activity in vivo. We further design TRTAC-drug conjugates (TRTAC-DCs) by attaching cytotoxic payloads to TRTACs, enabling targeted protein degradation together with enhanced drug delivery. TRTAC-DCs show significantly enhanced activity against HER2- and EGFR-positive tumors both in vitro and in vivo, with minimal toxicity observed in normal tissues. These findings establish TROP2 as a robust LTR and provide a versatile eTPD platform with profound translational potential for tumor treatment.
Lysosome-targeting chimeras (LYTACs) induce lysosomal degradation of extracellular and membrane proteins by bridging target proteins with lysosomal trafficking receptors. However, conventional LYTACs often suffer from off-tissue effects, whereas reported tissue-specific LYTACs typically display limited degradation efficiency. To address these challenges, we report a chemically activatable LYTAC platform that leverages tumor microenvironment-specific cues to achieve precise and safe protein degradation in vivo. We designed a glutathione (GSH)-responsive caged mannose-6-phosphate glycan, GSH-pM6P, which was selectively activated within tumor microenvironments characterized by elevated GSH levels. Based on this design, GSH-pM6P was conjugated to an anti-PD-L1 antibody to construct a prodrug-type Pro-LYTAC. In a triple-negative breast cancer mouse model, Pro-LYTAC selectively degraded PD-L1 within tumor tissues, effectively inhibited tumor growth, and markedly reduced hepatic off-target toxicity. Collectively, Pro-LYTAC enabled tumor-specific degradation of target proteins, significantly enhancing the safety and therapeutic window of lysosome-targeted degradation strategies in cancer therapy.
Mohan Chen, Yicun Li, Xueting Wei et al.· Journal of Medicinal Chemist...· 0 citations
The development of proteolysis-targeting chimeras (PROTACs) represents a promising strategy for targeted protein degradation in cancer therapy. However, the limited tumor-specific targeting and the inherent unfavorable physicochemical properties of PROTACs lead to insufficient cellular uptake and suboptimal antitumor immune responses. Herein, as a proof of concept, we developed an oncolytic virus-PROTAC conjugate (BPAD) by efficiently coupling bromodomain-containing protein 4 (BRD4)-targeting PROTACs with oncolytic viruses (OVs). In BPAD, the potent and highly selective infection of OVs to tumor cells enhances both cellular uptake and tumor-selective delivery of PROTACs, resulting in a 640-fold increase in the protein degradation efficiency. Moreover, prior to OV-induced tumor lysis, the preferential replication of OVs within tumor cells, combined with BRD4 degradation, promotes the secretion of type I interferons and facilitates dendritic cell maturation. Overall, the BPAD strategy enables the development of biologically derived macromolecular PROTAC conjugates, thereby enhancing the clinical translation potential of diverse PROTACs.
Microbial cell therapies hold considerable promise as programmable and versatile modalities for targeted interventions in complex biological environments. Here, we developed a living bacterial delivery platform that could leverage its endogenous metabolism to synchronize the release of surface-anchored targeted protein degradation (TPD) chimeras and the secretion of immune-modulatory nanobodies (Nbs) for enhanced antitumor efficacy. By means of metabolic labeling coupled with bioorthogonal click chemistry, transferrin (Tf)-CD24 antibody chimeras (TransCACs) were covalently displayed on the surface of nonpathogenic Escherichia coli (E. coli) K12. In parallel, this strain was equipped with a constitutive expression module for the in situ biosynthesis of PD-L1-blocking nanobodies. Capitalizing on the natural tumor tropism of bacteria, our engineered E. coli K12 achieved tumor-targeted CD24 degradation, thereby augmenting macrophage-mediated phagocytosis and synergizing with PD-L1 blockade to elicit robust tumor-specific CD8+ T cell immunity. In vivo administration of engineered microbes led to marked tumor growth inhibition in both subcutaneous breast and orthotopic hepatocellular carcinoma models, along with prolonged animal survival, driven by remodeling of the suppressive tumor microenvironment through coordinated crosstalk between M1-like macrophages and tumor-resident memory (TRM)-like CD8+ T cells. Altogether, this integrated genetic engineering and metabolic labeling of bacteria (InGeM) opens avenues for the development of next-generation microbe-based cancer immunotherapies.
Xinping Hu, Yu Chen, Meiyuan Jin et al.· Journal of the American Chem...· 0 citations
Proteolysis-targeting chimeras (PROTACs) are currently constrained by a reliance on ubiquitously expressed E3 ligases, which compromises tumor selectivity and raises toxicity risks. Here, we identified KLHL12 as a potentially tumor-selective E3 ligase and reported the development of the first-in-class KLHL12-recruiting PROTACs. Guided by a structure-based macrocyclization strategy, we obtained a high‑affinity cyclic peptide, cp4, as a KLHL12‑binding ligand and constructed novel PROTACs against oncogenic BRD4 and EGFR. The optimal compound k12bp-1 achieved tumor-selective BRD4(L) degradation in A549 cells, significantly inhibiting cell proliferation and driving cell apoptosis while sparing normal cells. It demonstrated robust in vivo antitumor efficacy in A549 xenograft mouse models without observable systemic toxicity. Collectively, this work established KLHL12 as a promising tumor‑selective E3 ligase and provided a KLHL12-recruiting PROTAC platform for cancer therapy.
Shicheng Xu, Xian Zhang, Shun-Bo Hu et al.· Angewandte Chemie· 0 citations
Dysregulation of membrane proteins underlies various human diseases, with their overexpression or mutation frequently being associated with cancer progression. Although targeted protein degradation technologies such as proteolysis-targeting chimeras and lysosome-targeting chimeras represent promising therapeutic strategies, their efficacy is often limited by scarce targeting ligands, complex preparation procedures, potential immunogenicity, and other factors. Here, we present a lysosome-targeting degradation platform based on circular bivalent aptamer chimeras (CBACs), which simultaneously engage the lysosomal shuttle receptor LDLR and target membrane proteins. Leveraging the natural LDLR recycling pathway, CBAC triggers receptor-mediated endocytosis and lysosomal degradation while recycling the LDLR. We demonstrate efficient and selective degradation of two cancer-therapeutically relevant membrane proteins, c-Met and PTK7, in multiple cancer cells, leading to apoptosis and reduced invasion and migration. Given its modular design and reliance on endogenous trafficking machinery, this platform holds broad potential for the degradation of diverse membrane proteins and could facilitate the development of new therapeutic modalities.
Ningyi Li, Zhenzhen Guo, Ruirui Zhang et al.· Journal of Medicinal Chemist...· 0 citations
Trophoblast cell-surface antigen 2, encoded by TACSTD2, is a transmembrane glycoprotein with broad expression in epithelial malignancies and limited, compartmentalized expression in many normal adult tissues. Its tumor-associated distribution, rapid internalization, and functional connection with proliferation, epithelial-mesenchymal transition, stem-like phenotypes, chemoresistance, and survival signaling have made TROP2 both a biological driver and a therapeutic entry point. The clinical development of TROP2-directed antibody-drug conjugates has shifted the field from biomarker description toward target-enabled drug delivery. Sacituzumab govitecan established clinical proof of concept by coupling a TROP2 antibody with SN-38 through a hydrolysable linker, while datopotamab deruxtecan and sacituzumab tirumotecan illustrate newer strategies that refine payload chemistry, linker stability, drug-to-antibody ratio, and toxicity management. This review summarizes the molecular features and expression landscape of TROP2, the mechanisms through which TROP2 supports malignant progression, and the design logic and clinical status of representative TROP2-ADCs. Remaining issues include heterogeneous antigen expression, context-dependent signaling, payload resistance, lineage-specific toxicity, and the absence of standardized predictive assays. These issues frame the next stage of TROP2-targeted therapy.
Meijia Li· Theoretical and Natural Scie...· 0 citations