Next generation oncolytic viruses expressing PADI1 and TIMP2 exhibit anti-tumor activity against melanoma in nude and humanized mouse models

Immunotherapy of metastatic melanoma (MM) has vastly improved the longevity of only a minority of patients. To broaden the repertoire of agents against MM, we investigated the effectiveness of locally interrupting tumor blood endothelial cell proliferation and angiogenesis, arginine deprivation, or both on the growth of melanoma by constructing and characterizing the effectiveness of four oncolytic adenoviruses. ONCOS-207 (which expressed tissue inhibitor of metalloprotease type 2 [TIMP2]), ONCOS-209 (which expressed peptidyl arginine deiminase [PADI1]), and ONCOS-210 and ONCOS212 (which expressed both TIMP2 and PADI1) exhibited oncolytic activity against four melanoma cell lines in vitro. ONCOS212 treatments significantly inhibited tumor growth in an A2058 tumor model in nude mice compared with vehicle control. The inhibitory effects of the two transgenes of ONCOS212 on tumor growth appeared to be synergistic. These viruses also significantly inhibited tumor growth in a humanized NOG model of melanoma (A2058 xenograft). All viruses significantly increased the percentage of activated CD8+ T cells in the tumor-infiltrating lymphocytes. The abscopal effect of ONCOS212 treatments in the A2058 tumor challenge model in hNOG mice supports the hypothesis that the human immune response contributes to the anti-tumor activity of ONCOS212. These results support the further development of ONCOS-212 for cancer treatment.