Photothermal therapy co-localized with CD137 agonism improves survival in an SM1 melanoma model without hepatotoxicity

Aim: We investigate combining Prussian Blue nanoparticles (PBNPs), as photothermal therapy (PTT) agents, with agonistic CD137 antibodies (αCD137) on a single nanoparticle platform to deliver non-toxic, anti-tumor efficacy in SM1 murine melanoma. Methods: We electrostatically coated PBNPs with αCD137 (αCD137-PBNPs) and quantified their physicochemical characteristics, photothermal and co-stimulatory capabilities. Next, we tested the efficacy and hepatotoxicity of PTT using αCD137-PBNPs (αCD137-PBNP-PTT) in SM1 tumor-bearing mice. Results: The αCD137-PBNPs retained both the photothermal and agonistic properties of the PBNPs and αCD137, respectively. In vivo, SM1 tumor-bearing mice treated with αCD137-PBNP-PTT exhibited a significantly higher survival rate (50%) without hepatotoxicity, compared with control treatments. Conclusion: These data suggest the potential utility of co-localizing PBNP-PTT with αCD137-based agonism as a novel combination nanomedicine.