194. Adenoviruses Armed with TNFα and IL-2 Successfully Enable Adoptive T-Cell Therapy

The field of T-cell therapy of cancer holds great promise, as demonstrated by the results obtained in Chimeric Antigen Receptor (CAR) modified T-cell therapy of CD19+ leukemia. However, the approach has not yielded similar results in the treatment of solid tumors with the exception of tumor infiltrating lymphocyte (TIL) therapy of melanoma. Recent work has identified key obstacles which has limited the efficacy of the approach: i) lack of recruitment of transferred T-cells to the tumor due to lack of trafficking signals ii) anergy of transferred cells at the tumor due to tumor immunosuppression iii) lack of propagation of transferred T-cells at the tumor. Previously, we have identified interleukin 2 (IL-2) and Tumor Necrosis Factor alpha (TNFα) as the most promising factors to stimulate the graft used in adoptive T-cell therapy. Both cytokines are important activators of immune cells and also known for their direct anti-tumor properties. Notably, these cytokines can cause severe side effects when administered systemically. Previously, we and others have achieved long lasting, high level cytokine expression locally but low level systemically when using armed oncolytic viruses in vivo. Oncolytic viruses armed with immunostimulatory molecules constitute a potent form of immunotherapy. In essence, the danger signal caused by virus replication, coupled with the actions of the transgene, and effective presentation of tumor epitopes by lysis of the cells, results in a personalized cancer vaccine. One attractive aspect of this approach is the ease of combinations with standard therapies including chemotherapy, radiation and immune checkpoint inhibiting antibodies for example. Therefore, we developed oncolytic adenoviruses expressing one or both above mentioned human cytokines. For more detailed immunological studies in immune competent mouse models, we constructed non-replicative adenoviruses with murine cytokines (Ad5-CMV-mIL2 and Ad5-CMV-mTNFα). These viruses were studied in combination with adoptive transfer of OT-1 TCR transgenic T-cells to treat C57BL/6 mice bearing B16-OVA melanoma tumors. The animals were administered intraperitoneally with CD8+-enriched OT-1 cells with or without intratumoral injections of cytokine-coding viruses. Combination treatment with Ad5-CMV-mIL2 and OT-1 resulted in statistically significant antitumor efficacy when compared with either monotherapy or untreated control. In further experiments a triple combination of Ad5-CMV-mIL2 + Ad5-CMV-mTNFa and OT-1 T-cells improved antitumor efficacy was observed over dual agent therapies. Furthermore, in Syrian hamster model, oncolytic virus successfully improved the efficacy of TIL therapy. Additionally, splenocytes derived from animals treated with the combination of Ad5-D24 and TIL killed autologous tumor cells more efficiently than monotherapy-derived splenocytes.