Abstract 1877: Tripokin: potential best-in-class for tumor targeted interleukin-2 (IL2) potentiated by tumor necrosis factor (TNF)

Abstract Among the different pharmacological approaches for cancer treatment, antibody-cytokine fusion proteins (also called “immunocytokines”) represent an emerging class of biopharmaceutical products, capable of boosting the immune system to attack tumor cells as a result of a selective accumulation of pro-inflammatory molecules at the site of disease. When used as single agents, immunocytokines are often not able to cure mice and patients. However, it has been shown by our group that the combination of IL2- and TNF- based products was able to completely eradicate tumors in mouse models and to induce complete responses in cancer patients. We have previously described a novel class of immunocytokine products, termed “potency-matched dual cytokine antibody fusion proteins”, consisting of a tumor-targeting antibody (the F8 antibody, specific to the alternatively spliced EDA domain of fibronectin), simultaneously fused to both IL2 and TNF. To match biological activity of the two payloads a single-point mutation was inserted in the TNF sequence and the resulting product, named IL2-F8-TNFmut was able to selectively localize to tumors with excellent tumor-to-organ ratios and it was found to completely eradicate soft-tissue sarcomas in immunocompetent mice, which did not respond to standard chemotherapy. Moreover, the immunocytokine was able to induce complete responses in a variety of mouse models of cancer. The therapeutic activity was further improved when IL2-F8-TNFmut was used in combination with immune checkpoint inhibitors. At the mechanistic level we observed that the anticancer activity was completely abrogated when CD4+ and CD8+ T cells were depleted, while the contribution of NK cells was negligible. We now report the generation of a new potency-matched dual cytokine antibody fusion protein, named Tripokin based on the L19 antibody, specific to the alternatively spliced EDB domain of fibronectin. Compared to the previous product, Tripokin showed a favorable pharmacokinetic profile in monkey, an excellent localization to neoplastic lesions in mice and was easier to formulate for further clinical applications. When tested in tumor bearing mice, Tripokin revealed a superior anti-cancer activity compared to other IL2-based products.The results obtained in this work provided a rationale for future clinical translation activities using Tripokin as potential best-in-class tumor targeted IL2 product. Citation Format: Eleonora Prodi, Riccardo Corbellari, Mattia Matasci, Dario Neri, Roberto De Luca. Tripokin: potential best-in-class for tumor targeted interleukin-2 (IL2) potentiated by tumor necrosis factor (TNF) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1877.