Mitigating Doxorubicin‐Induced Cardiotoxicity and Enhancing Anti‐Tumor Efficacy with a Metformin‐Integrated Self‐Assembled Nanomedicine

Doxorubicin (Dox) is a potent chemotherapeutic agent commonly used in cancer treatment. However, cardiotoxicity severely limited its clinical application. To address this challenge, a novel self-assembled nanomedicine platform, PMDDH, is developed for the co-delivery of Dox and metformin, an antidiabetic drug with cardioprotective and anti-tumor properties. PMDDH integrates metformin into a polyethyleneimine-based bioactive excipient (PMet), with Dox intercalated into double-stranded DNA and a hyaluronic acid (HA) coating to enhance tumor targeting. The PMDDH significantly improves the pharmacokinetics and tumor-targeting capabilities of Dox, while metformin enhances the drug's anti-tumor activity by downregulating programmed cell death ligand 1 (PD-L1) and activating the AMP-activated protein kinase (AMPK) signaling pathway. Additionally, the DNA component stimulates the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, which synergizes with Dox-induced immunogenic cell death (ICD) to promote a robust anti-tumor immune response. PMDDH markedly reduces Dox-induced cardiotoxicity by preserving mitochondrial function, reducing reactive oxygen species (ROS) production, and inducing protective autophagy in cardiomyocytes. These findings position PMDDH as a promising dual-function nanomedicine that enhances the anti-tumor efficacy of Dox while minimizing its systemic toxicity, offering a safer and more effective alternative for cancer therapy.