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

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. 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. The αCD137-PBNPs retained both the photothermal and agonistic properties of the PBNPs and αCD137, respectively. , SM1 tumor-bearing mice treated with αCD137-PBNP-PTT exhibited a significantly higher survival rate (50%) without hepatotoxicity, compared with control treatments. These data suggest the potential utility of co-localizing PBNP-PTT with αCD137-based agonism as a novel combination nanomedicine.