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

Yunching Chen,Annique M Duyverman,Cyril H Benes,Yun‐Chieh Sung ,Ya Chi Liu ,Shuji Kitahara,Andrew X Zhu,Lin Ts ,Chun Hung Liu ,Irinel Popescu,Nabeel Bardeesy,Keith T Flaherty,Rakesh K Jain,Kuo‐Shyang Jeng ,Peigen Huang,Dong Gao ,Rakesh R Ramjiawan,Chih Chun Chang ,Chiung Fang Chang ,Simona Dima,Fu Fei Hsu ,Dan G Duda

doi:10.1038/srep44123

Abstract

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.

Highlights

The efficacy of targeted therapy with kinase inhibitors in cancer is often limited by rapid treatment evasion
Similar to the ERK activation seen in hepatocellular carcinoma (HCC) cells in vitro, we found that sorafenib increased ERK activation in orthotopic Hep3B xenografts and in two murine models of spontaneous HCC (Fig. 1c–e)[22,23]
Co-delivery of sorafenib and the MEK inhibitor AZD6244 by the tumor-targeted nanoparticles prevents the paradoxical activation of ERK and programmed death-1-ligand 1 (PD-L1) expression and facilitates intra-tumoral infiltration of cytotoxic CD8+ T cells in HCC, resulting in enhanced anti-tumor efficacy. To overcome this evasion mechanism and reduce systemic toxicities, we developed tumor-targeted nanoparticles (TTNPs), with the structure shown in Fig. 4a, to co-deliver sorafenib with a MEK inhibitor into HCC

Summary

Introduction

The efficacy of targeted therapy with kinase inhibitors in cancer is often limited by rapid treatment evasion. Treatment resistance may develop either due to additional mutations, by alternate mode of activation of the same pathway or alternative oncogenic pathways, or by dynamic reprogramming of the kinome[1,2,3] One such mechanism is the “paradoxical” activation of MAP kinase (MAPK) pathway (RAF/MEK/ERK) by RAF inhibitors leading to adverse effects[4]. The use of RAF inhibitors such as vemurafenib or sorafenib in BRAF-wild-type cancers has been shown to lead to “paradoxical” activation of ERK in cutaneous squamous cell carcinoma, lung cancer or melanoma, likely due to a direct effect of the drug on RAF dimerization[2,4,5]. We examined the relevance of ERK activation in HCCs treated with sorafenib (the only approved systemic therapy for this disease), and developed a safer nanoparticle-based multi-drug delivery system to overcome treatment resistance

Methods

Results

Conclusion