Engineered Tumor‐Homing Escherichia coli for Localized Hyaluronic Acid Degradation and Stromal Remodeling in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) accumulates vast amounts of hyaluronic acid (HA), generating a rigid, high‐pressure stroma that blocks drug delivery and infiltration. Although hyaluronidase (HAase) can dismantle this barrier, systemic administration of HAase depletes HA from healthy tissues and causes dose‐limiting toxicities. Here we exploited the inherent hypoxia‐driven tumor‐homing capacity of Escherichia coli BL21 to create an autonomous, self‐amplifying delivery system (SHEc) that synthesized and secreted the highly active HA‐specific HAase (SHAase) from Streptomyces koganeiensis exclusively within the tumor. Guided by the pelB signal peptide, SHAase could be translocated to the periplasm and released into the extracellular space only where SHEc accumulates. In vitro, SHEc selectively colonized the necrotic core of HA‐rich multicellular tumor spheroids (MCTS) formed by Panc02 cells and TGF‐β‐activated NIH/3T3 cancer‐associated fibroblasts, degrading 44.43% of HA within 24 h. This on‐site HA digestion increased drug penetration depth by 2.92‐fold, decreased hypoxic fraction by 54.81%, and enhanced gemcitabine‐induced apoptosis. Thus, SHEc converts a systemically toxic protein into a tumor‐restricted stromal remodeling agent, offering a safe and potent strategy to enhance chemotherapy against PDAC.