Combined delivery of sorafenib and a MEK inhibitor using CXCR4-targeted nanoparticles reduces hepatic fibrosis and prevents tumor development.

Liver damage and fibrosis are precursors of hepatocellular carcinoma (HCC). In HCC patients, sorafenib-a multikinase inhibitor drug-has been reported to exert anti-fibrotic activity. However, incomplete inhibition of RAF activity by sorafenib may also induce paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway in malignant cells. The consequence of this effect in non-malignant disease (hepatic fibrosis) remains unknown. This study aimed to examine the effects of sorafenib on activated hepatic stellate cells (HSCs), and develop effective therapeutic approaches to treat liver fibrosis and prevent cancer development. Methods: We first examined the effects of sorafenib in combination with MEK inhibitors on fibrosis pathogenesis in vitro and in vivo. To improve the bioavailability and absorption by activated HSCs, we developed CXCR4-targeted nanoparticles (NPs) to co-deliver sorafenib and a MEK inhibitor to mice with liver damage. Results: We found that sorafenib induced MAPK activation in HSCs, and promoted their myofibroblast differentiation. Combining sorafenib with a MEK inhibitor suppressed both paradoxical MAPK activation and HSC activation in vitro, and alleviated liver fibrosis in a CCl4-induced murine model of liver damage. Furthermore, treatment with sorafenib/MEK inhibitor-loaded CXCR4-targeted NPs significantly suppressed hepatic fibrosis progression and further prevented fibrosis-associated HCC development and liver metastasis. Conclusions: Our results show that combined delivery of sorafenib and a MEK inhibitor via CXCR4-targeted NPs can prevent activation of ERK in activated HSCs and has anti-fibrotic effects in the CCl4-induced murine model. Targeting HSCs represents a promising strategy to prevent the development and progression of fibrosis-associated HCC.

Overcoming sorafenib evasion in hepatocellular carcinoma using CXCR4-targeted nanoparticles to co-deliver MEK-inhibitors.

Sorafenib is a RAF inhibitor approved for several cancers, including hepatocellular carcinoma (HCC). Inhibition of RAF kinases can induce a dose-dependent "paradoxical" upregulation of the downstream mitogen-activated protein kinase (MAPK) pathway in cancer cells. It is unknown whether "paradoxical" ERK activation occurs after sorafenib therapy in HCC, and if so, if it impacts the therapeutic efficacy. Here, we demonstrate that RAF inhibition by sorafenib rapidly leads to RAF dimerization and ERK activation in HCCs, which contributes to treatment evasion. The transactivation of RAF dimers and ERK signaling promotes HCC cell survival, prevents apoptosis via downregulation of BIM and achieves immunosuppression by MAPK/NF-kB-dependent activation of PD-L1 gene expression. To overcome treatment evasion and reduce systemic effects, we developed CXCR4-targeted nanoparticles to co-deliver sorafenib with the MEK inhibitor AZD6244 in HCC. Using this approach, we preferentially and efficiently inactivated RAF/ERK, upregulated BIM and down-regulated PD-L1 expression in HCC, and facilitated intra-tumoral infiltration of cytotoxic CD8+ T cells. These effects resulted in a profound delay in tumor growth. Thus, this nano-delivery strategy to selectively target tumors and prevent the paradoxical ERK activation could increase the feasibility of dual RAF/MEK inhibition to overcome sorafenib treatment escape in HCC.

Development and characterization of sorafenib-loaded PLGA nanoparticles for the systemic treatment of liver fibrosis.

Sorafenib is a tyrosine kinase inhibitor that has recently been shown to be a potential antifibrotic agent. However, a narrow therapeutic window limits the clinical use and therapeutic efficacy of sorafenib. Herein, we have developed and optimized nanoparticle (NP) formulations prepared from a mixture of poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) (PEG-PLGA) copolymers with poly(lactic-co-glycolic acid) (PLGA) for the systemic delivery of sorafenib into the fibrotic livers of CCl4-induced fibrosis mouse models. We characterized and compared the pharmaceutical and biological properties of two different PLGA nanoparticles (NPs)--PEG-PLGA NPs (PEG-PLGA/PLGA=10/0) and PEG-PLGA/PLGA NPs (PEG-PLGA/PLGA=5/5). Increasing the PLGA content in the PEG-PLGA/PLGA mixture led to increases in the particle size and drug encapsulation efficacy and a decrease in the drug release rate. Both PEG-PLGA and PEG-PLGA/PLGA NPs significantly prolonged the blood circulation of the cargo and increased the uptake by the fibrotic livers. The systemic administration of PEG-PLGA or PEG-PLGA/PLGA NPs containing sorafenib twice per week for a period of 4 weeks efficiently ameliorated liver fibrosis, as indicated by decreased α-smooth muscle actin (α-SMA) content and collagen production in the livers of CCl4-treated mice. Furthermore, sorafenib-loaded PLGA NPs significantly shrank the abnormal blood vessels and decreased microvascular density (MVD), leading to vessel normalization in the fibrotic livers. In conclusion, our results reflect the clinical potential of sorafenib-loaded PLGA NPs for the prevention and treatment of liver fibrosis.

Delivery of siRNA Using CXCR4-targeted Nanoparticles Modulates Tumor Microenvironment and Achieves a Potent Antitumor Response in Liver Cancer.

Antiangiogenic therapy has recently emerged as a highly promising therapeutic strategy for treating hepatocellular carcinoma (HCC). However, the only clinically approved systemic antiangiogenic agent for advanced HCC is sorafenib, which exerts considerable toxicity. Moreover, acquired resistance to antiangiogenic therapy often develops and restricts the therapeutic efficacy of this treatment. Hence, in this study, we develop a CXCR4-targeted lipid-based nanoparticle (NP) formulation to specifically deliver vascular endothelial growth factor (VEGF) siRNA as an antiangiogenic substance into HCC. AMD3100, a CXCR4 antagonist, is added into NPs to serve as both a targeting moiety and a sensitizer to antiangiogenic therapy. We demonstrate that AMD-modified NPs (AMD-NPs) can efficiently deliver VEGF siRNAs into HCC and downregulate VEGF expression in vitro and in vivo. Despite the upregulation of the SDF1α/CXCR4 axis upon the induction of hypoxia after antiangiogenic therapy, CXCR4 inhibition by AMD-NPs in combination with either conventional sorafenib treatment or VEGF siRNA prevents the infiltration of tumor-associated macrophages. These dual treatments also induce synergistic antiangiogenic effects and suppress local and distant tumor growth in HCC. In conclusion, the tumor-targeted multifunctional AMD-NPs that co-deliver VEGF siRNA and AMD3100 provide an effective approach for overcoming tumor evasion of antiangiogenic therapy, leading to delayed tumor progression in HCC.

CXCR4-targeted lipid-coated PLGA nanoparticles deliver sorafenib and overcome acquired drug resistance in liver cancer.

Sorafenib, a multikinase inhibitor, has been used as an anti-angiogenic agent against highly vascular hepatocellular carcinoma (HCC) - yet associated with only moderate therapeutic effect and the high incidence of HCC recurrence. We have shown intratumoral hypoxia induced by sorafenib activated C-X-C receptor type 4 (CXCR4)/stromal-derived factor 1α (SDF1α) axis, resulting in polarization toward a tumor-promoting microenvironment and resistance to anti-angiogenic therapy in HCC. Herein, we formulated sorafenib in CXCR4-targeted lipid-coated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) modified with a CXCR4 antagonist, AMD3100 to systemically deliver sorafenib into HCC and sensitize HCC to sorafenib treatment. We demonstrated that CXCR4-targeted NPs efficiently delivered sorafenib into HCCs and human umbilical vein endothelial cells (HUVECs) to achieve cytotoxicity and anti-angiogenic effect in vitro and in vivo. Despite the increased expression of SDF1α upon the persistent hypoxia induced by sorafenib-loaded CXCR4-targeted NPs, AMD3100 attached to the NPs can block CXCR4/SDF1α, leading to the reduced infiltration of tumor-associated macrophages, enhanced anti-angiogenic effect, a delay in tumor progression and increased overall survival in the orthotopic HCC model compared with other control groups. In conclusion, our results highlight the clinical potential of CXCR4-targeted NPs for delivering sorafenib and overcoming acquired drug resistance in liver cancer.