Defeating Melanoma Through a Nano-Enabled Revision of Hypoxic and Immunosuppressive Tumor Microenvironment

Abstract

Rationale: Reversing the hypoxic and immunosuppressive tumor microenvironment (TME) is crucial for treating malignant melanoma. Seeking a robust platform for the effective reversion of hypoxic and immunosuppressive TME may be an excellent solution to revolutionizing the current landscape of malignant melanoma treatment. Here, we demonstrated a transdermal and intravenous dual-administration paradigm. A tailor-made Ato/ [email protected] NPs were administrated transdermally to melanoma with the help of a gel spray containing a skin-penetrating material borneol. Nanoparticles encased Ato and cabo were released and thereby reversed the hypoxic and immunosuppressive tumor microenvironment (TME). Methods: Ato/ [email protected] NPs were synthesized through a self-assembly emulsion process, and the transdermal ability was assessed using Franz diffusion cell assembly. The inhibition effect on cell respiration was measured by OCR, ATP, and pO 2 detection and in vivo photoacoustic (PA) imaging. The reversing of the immunosuppressive was detected through flow cytometry analysis of MDSCs and T cells. At last, the in vivo anti-tumor efficacy and histopathology, immunohistochemical analysis and safety detection were performed using tumor-bearing mice. Results: The transdermally administrated Ato/ [email protected] NPs successfully spread to the skin surface of melanoma and then entered deep inside the tumor with the help of a gel spray and a skin puncturing material borneol. Atovaquone (Ato, a mitochondrial-respiration inhibitor) and cabozantinib (cabo, a MDSCs eliminator) were concurrently released in response to the intratumorally overexpressed H 2 O 2 . The released Ato and cabo respectively reversed the hypoxic and immunosuppressive TME. The reversed hypoxic TME offered sufficient O 2 for the intravenously administrated indocyanine green (ICG, an FDA-approved photosensitizer) to produce adequate amount of ROS. In contrast, the reversed immunosuppressive TME conferred amplified systemic immune responses. Conclusion: Taken together, we developed a transdermal and intravenous dual-administration paradigm, which effectively reversed the hypoxic and immunosuppressive tumor microenvironment in the treatment of the malignant melanoma. We believe our study will open a new path for the effective elimination of the primary tumors and the real-time control of tumor metastasis. Keywords: melanoma, tumor microenvironment, hypoxia, immunosuppression, transdermal administration

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