Tumor endothelial cell and cancer cell targeting anti-PRND antibody-drug conjugate to treat hypervascular tumors such as glioblastoma and sarcomas

Antibody-drug conjugates (ADCs) have emerged as a major class of targeted therapeutics but remain limited by poor tumor penetration, antigen heterogeneity, and a narrow therapeutic window. To overcome these limitations, we developed an anti-PRND ADC targeting PRND (Doppel), a prion-like glycoprotein selectively expressed in tumor endothelial cells (TECs) and cancer cells but absent in normal tissues except in the testis. This localization enables direct vascular targeting without diffusion barriers and provides a unique opportunity for precise drug delivery to the tumor vasculature. The resulting antibody-drug conjugate, 3H9-KGDEVD-MMAE, is a homogeneous ADC (DAR = 8) free of soluble aggregates. It couples a high-affinity anti-PRND antibody (3H9) with a caspase/cathepsin B-cleavable KGDEVD linker that can be specifically cleaved by both cathepsin B and caspase-3/7. This dual activation allows MMAE release through lysosomal cathepsin B and induces apoptosis of PRND positive cells, and caspase-3/7 from the apoptosis of target cells induces the apoptosis of adjacent tumor tissues. The caspase-mediated cleavage establishes an in-situ feedback amplification loop that maintains continuous local drug release, sustained cytotoxicity, and producing a potent bystander effect that overcomes antigen heterogeneity. By combining TEC and cancer cell-specific targeting with a caspase/cathepsin-responsive linker, 3H9-KGDEVD-MMAE (anti-PRND ADC), achieves deep intratumoral penetration, robust vascular disruption, and durable antitumor efficacy. In preclinical models of glioblastoma, sarcoma, and renal cell carcinoma (RCC) - hypervascular malignancies with limited ADC options, anti-PRND ADC induced extensive and durable tumor regressions without systemic toxicity. Collectively, these findings establish anti-PRND ADC as a next-generation vascular-disrupting ADC, integrating endothelial docking with apoptosis-triggered drug amplification for potent and selective control of highly vascularized tumors. Acknowledgments: This research was supported by the Korea Drug Development Fund (HN21C0264) funded by the Ministry of Science and ICT and the National Research Foundation of Korea (NRF) grant (2020R1A2C2015026) funded by the Korea government (MSIT).