Abstract 2785: Potency-matched dual cytokine antibody fusion proteins in combination with PD-L1 blockade

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. These products promote the selective accumulation of pro-inflammatory molecules at the site of disease, mediated by the antibody fragment. These fusion proteins have been designed to reduce the systemic toxicity of traditional cytokines, currently approved for certain malignancies. Immunocytokine products based on interleukin-2 (IL2), interleukin-12 (IL12) or tumor necrosis factor (TNF) have been extensively studied in mouse model of cancer and in patients. When used as single agents, immunocytokines are often not able to cure mice and patients. However it as been shown by our group that the combination of IL2- and TNF- based products was capable to completely eradicate tumors in mouse models and to induce complete responses in patients. The development of combination products at the industrial level leads to a duplication of activities and costs. On the other hand, the opportunity to develop products with two payloads fused into a single molecular entity may facilitate development. This approach is limited by the fact that different cytokines often show different maximal tolerated doses (MTDs), and their relative potency need to be tuned. For example, TNF is administered at a dose, which is ten times lower compered to the one of IL2. We have recently described a novel class of immunocytokine products, termed “potency-matched dual cytokine antibody fusion proteins” consisting of a tumor-targeting antibody (for example F8, 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 lesions with an 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. We now report that complete responses were observed in a variety of mouse models of cancer and that the therapeutic efficacy of IL2-F8-TNFmut was further improved when used in combination with an anti-PD-L1 antibody. Potency-matched dual cytokine antibody fusion proteins may find clinical applications for various types of malignancies, used either as single agents or in combination with immune-checkpoint inhibitors. Citation Format: Roberto De Luca, Dario Neri. Potency-matched dual cytokine antibody fusion proteins in combination with PD-L1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2785.