Porous Microspheres Dual-loaded with Doxorubicin and Tirapazamine to Introduce Synergistic Hepatocellular Carcinoma Treatment via Transcatheter Embolization

Trans-arterial chemoembolization (TACE) i.e., blockage of blood supply while administering chemotherapy medications to the tumor, is the most common treatment strategy for intermediate and advanced stage of unresectable Hepatocellular carcinoma (HCC). However, HCC characterized with poor prognosis akin to hypoxia caused by the tumor-derived microenvironment and TACE procedure itself, and thus become a desirable therapeutic target. In this study we have fabricated microspheres (MS) with unique porous morphology that presented high site-specific localization and drug release combining Doxorubicin (DOX) chemotherapy, and Tirapazamine (TPZ) which is a hypoxia-activated prodrug targeting specifically hypoxic tumor cells. Liver cancer cells HepG2, Huh7 (human) and N1-S1 (rattus) were exposed to doxorubicin under normoxia or hypoxia regimen. Hypoxia found to decrease HepG2 viability and tolerance to DOX, while Huh7 and N1-S1 exhibited no vitality sensitivity, and increased tolerance to DOX. The combination of DOX and TPZ under hypoxia revealed synergism, effectively inhibiting N1-S1 proliferation. Moreover, a novel in-vitro model mimicking hepatic embolization based on a microfluidic chip was developed. Tumor-bearing N1-S1 hepatoma rat model was established and performed TACE to investigate the in-vivo drug tissue distribution, antitumor efficiency, and biosafety profile. Rats treated with porous DOX-TPZ MS showed lower size increment of tumor, enhanced necrosis, high intra-tumoral drug concentration and verified the synergism of DOX and TPZ compared to other treated groups. These findings suggest that porous DOX-TPZ MS can be used as a promising drug delivery system in TACE for liver tumors and could be further expanded to treat other types of cancers.