Single-Dose\nPhysically Cross-Linked Hyaluronic Acid\nand Lipid Hybrid Nanoparticles Containing Cyclic Guanosine Monophosphate–Adenosine\nMonophosphate Eliminate Established Tumors

Activating the STING pathway in the\ncytosol of tumor-infiltrating\nantigen-presenting cells (APCs) represents a promising strategy to\nelicit potent antitumor immune responses for cancer therapy. However,\nSTING agonists are mostly small hydrophilic molecules that suffer\nfrom rapid clearance and poor cytosolic delivery following systemic\nadministration. While various nanoparticles have been developed to\npromote cytosolic delivery, they often exhibit premature drug release\nduring circulation. Alternatively, stable nanoparticles with sustained\nrelease during circulation have poor cytosolic delivery. In this study,\nwe have developed physically cross-linked hyaluronic acid (HA) and\nlipid hybrid nanoparticles containing cyclic guanosine monophosphate–adenosine\nmonophosphate (cGAMP), denoted as HLHC, to address these challenges.\nThe HLH delivery system has sustained drug release due to multiple\nlipid layers physically cross-linked by HA. HLHC efficiently delivers\ncGAMP to the cytosol of APCs, inducing more IFNβ than cGAMP\nand liposomal cGAMP. HLH also improves the drug circulation time and\nbiodistribution to the tumor compared with the liposomal formulation\nand free drug. Strikingly, a single dose of HLHC, but not liposomal\ncGAMP or free cGAMP, elicits potent antitumor immunity and regresses\nestablished MC38 tumors. A single dose of HLHC even regresses established\nB16F10 tumors upon combination with αPD-L1. Moreover, cured\nanimals were protected from rechallenge with the same tumor cells.\nHLHC represents an efficient strategy to address delivery challenges\nassociated with STING agonists and may have broad applications for\nthe delivery of drugs acting in the cytosol.