A Dual Glutathione-Depleting Nanoparticle Loaded with Porcine Pancreatic Elastase for Neoadjuvant Chemotherapy of Triple Negative Breast Cancer

Neoadjuvant chemotherapy remains a central clinical strategy for triple negative breast cancer (TNBC), yet the lack of tumor-specific targets often results in variable treatment responses. Porcine pancreatic elastase (PPE), a natural protease with selective antitumor activity, is significantly limited by the tumor microenvironment, particularly due to elevated glutathione (GSH) levels. To address the limited therapeutic potential of PPE, we constructed PMC@HA nanoparticles by coencapsulating PPE within a bimetallic Cu/Zn nanocarrier and integrating the glutaminase inhibitor CB-839. The Cu/Zn carrier not only consumes intracellular GSH but also displays peroxidase-like catalytic behavior, generating cytotoxic • OH. CB-839 impedes mitochondrial GSH biosynthesis, enhances PPE-mediated hydrolysis and CD95 death domain release, and drives reactive oxygen species buildup in tumor cells. Furthermore, the combined action of PPE and CB-839 leads to lipid peroxide accumulation, mitochondrial collapse, and intensified tumor cell apoptosis. This multifunctional nanoplatform achieves strong tumor suppression and initiates immunogenic cell death, resulting in immune activation. When applied as a neoadjuvant regimen in conjunction with surgery, PMC@HA significantly decreases postoperative recurrence and distant metastasis in TNBC. This combinatorial approach may improve chemosensitivity and limit metastatic progression, thereby potentially extending long-term survival in patients with TNBC.