Pickering emulsion with tumor vascular destruction and microenvironment modulation for transarterial embolization therapy

Abstract

In the clinic, Lipiodol chemotherapeutic emulsions remain a main choice for patients diagnosed with hepatocellular carcinoma (HCC) via the mini-invasive transarterial chemoembolization (TACE) therapy. However, the poor stability of conventional Lipiodol chemotherapeutic emulsions would result in the fast drug diffusion and incomplete embolization, inducing systemic toxicity and impairing the efficacy of TACE therapy. Therefore, it is of great importance to construct alternative formulations based on commercial Lipiodol to achieve the improved efficacy and safety of HCC treatment. Herein, calcium phosphate (CaP) nanoparticles-stabilized Lipiodol Pickering emulsion (CaP-LPE) with improved stability and pH-responsiveness is prepared and utilized for the encapsulation of combretastatin A4-phosphate (CA4P), a clinically approved vascular disrupting agent. The obtained CA4P-loaded CaP-LPE (CCaP-LPE) was shown to be enhanced stability compared to conventional Lipiodol emulsion and pH-responsive release of the encapsulated drugs. On one hand, the released CA4P could disrupt tumor vascular and cut off the blood supplying of tumor cells, thus starving cancer cells. Moreover, it was revealed that CCaP-LPE could reverse immunosuppressive tumor microenvironment (TME) by neutralizing tumor acidity, leading to the increased infiltration of CD8⁺ T cells and the decreased percentages of immunosuppressive cells. As the result, such CCaP-LPE could effectively shrink orthotopic N1S1 HCC tumors in rats by eliciting a potent antitumor immune response. Therefore, this study highlights a simple strategy to construct a novel LPE with the potencies of tumor vascular disruption and TME modulation, holding a great promise for TAE therapy of HCC.

Keywords: Immunotherapy; Pickering emulsions; Transarterial chemoembolization (TACE); Tumor microenvironment; Vascular disrupting agents (VDAs).