CD274 and neoplasm: In an attempt to therapeutically exploit the ability of ONP-302 to upregulate PD-1/PD-L1 expression on tumor-infiltrating leukocytes, we asked if initial nanoparticle treatment followed by anti-PD-1 checkpoint inhibitor blockade would lead to longer-lived inhibition of growth of B16.F10 melanoma, a ‘cold’ tumor which does not respond to anti-PD-1 monotherapy (47).