EGFR-targeted multifunctional polymersomal doxorubicin induces selective and potent suppression of orthotopic human liver cancer in vivo

Abstract

Liver cancer is a globally leading malignancy that has a poor five-year survival rate of less than 20%. The systemic chemotherapeutics are generally ineffective for liver cancers partly due to fast clearance and low tumor uptake. Here, we report that GE11 peptide functionalized polymersomal doxorubicin (GE11-PS-DOX) effectively targets and inhibits epidermal growth factor receptor (EGFR)-positive SMMC7721 orthotopic human liver tumor xenografts in mice. GE11-PS-DOX with a GE11 surface density of 10% displayed a high drug loading of 15.4 wt%, a small size of 78 nm, and glutathione-triggered release of DOX. MTT assays, flow cytometry and confocal microscopy studies revealed that GE11-PS-DOX mediated obviously more efficient DOX delivery into SMMC7721 cells than the non-targeting PS-DOX and clinically used liposomal doxorubicin (Lipo-DOX) controls. The in vivo studies showed that GE11-PS-DOX had a long circulation time and an extraordinary accumulation in the tumors (13.3 %ID/g). Interestingly, GE11-PS-DOX caused much better treatment of SMMC7721 orthotopic liver tumor-bearing mice as compared to PS-DOX and Lipo-DOX. The mice treated with GE11-PS-DOX (12 mg DOX equiv./kg) exhibited a significantly improved survival rate (median survival time: 130 days versus 70 and 38 days for PS-DOX at 12 mg DOX equiv./kg and Lipo-DOX at 6 mg DOX equiv./kg, respectively) and achieved 50% complete regression. Notably, GE11-PS-DOX induced obviously lower systemic toxicity than Lipo-DOX. EGFR-targeted multifunctional polymersomal doxorubicin with improved efficacy and safety has a high potential for treating human liver cancers.

Statement of significance: Liver cancer is one of the top five leading causes of cancer death worldwide. The systemic chemotherapeutics and biotherapeutics generally have a low treatment efficacy for hepatocellular carcinoma partly due to fast clearance and/or low tumor uptake. Nanomedicines based on biodegradable micelle and polymersomes offer a most promising treatment for malignant liver cancers. Their clinical effectiveness remains, however, suboptimal owing to issues like inadequate systemic stability, low tumor accumulation and selectivity, and poor control over drug release. Here we report that GE11 peptide-functionalized, disulfide-crosslinked multifunctional polymersomal doxorubicin (GE11-PS-DOX) can effectively suppress the growth of orthotopic SMMC7721 human liver tumors in nude mice. They showed significantly decreased systemic toxicity and improved mouse survival rate with 3.4-fold longer median survival time as compared to clinically used pegylated liposomal doxorubicin (Lipo-DOX) and achieving 50% complete regression. GE11-PS-DOX, based on PEG-PTMC is biodegradable, nontoxic, and easy to prepare, appears as a safe, robust, versatile and all-function-in-one nanoplatform that has a high potential in targeted chemotherapy of EGFR expressed hepatocellular carcinoma.

Keywords: Biodegradable polymersomes; EGFR; Liver cancer; Targeted delivery.