Abstract 5563: Kinetically-controlled release of blocking molecules for the targeted enhancement of therapeutic activity in antibody-cytokine fusion proteins

Abstract

Abstract Cytokines are able to mediate a potent anticancer activity but have significant side effects that prevent dose escalation to therapeutically-active regimens. Targeting the cytokines to the site of disease helps to improve their therapeutic index while decreasing associated toxicities. However, peak concentrations in blood are still associated with side-effects. We have developed a novel technology (termed “CORK Technology”), which consists in masking the undesired activity of a cytokine in circulation. The “cork” can be either an antibody fragment or a small molecule, which specifically binds to the cytokine thus preventing the interaction with its receptor. Once the complex accumulates in the tumor, the cork dissociate from the cytokine allowing it to exert its function. Capitalizing on the fact that the kinetic dissociation constant koff of the complex is identical in different species, this technology can be easily translated from mouse to man with comparable results. In this poster we describe the experimental implementation of CORK Technology to improve the therapeutic index of the clinical stage L19-IL2 (L19 is an antibody fragment specific to the alternatively-spliced EDB domain of fibronectin, a marker of tumor angiogenesis). Two classes of IL2 inhibitors were discovered and characterized: (i) a fully human scFv fragment, and (ii) a small organic ligand, featuring a modified methylindole moiety. Both types of agents reduced IL2 activity in vitro, were able to dissociate from the cognate cytokine in a kinetically-tuned process and allowed the administration of the L19-IL2 fusion protein at higher doses, both in normal and in tumor-bearing mice. The technology is applicable to other cytokine payloads and facilitates the development of targeted cytokine products with “activity on demand” (i.e., with increased activity at the tumor site, promoting an activation and proliferation of tumor-resident lymphocytes). Albeit still in its infancy, this elegant approach provides promising results and a strong rationale to further investigate this therapeutic power of the CORK Technology. Citation Format: Tiziano Ongaro, Martina Bigatti, Filippo Sladojevich, Etienne Donckele, Alessandra Micaela Villa, Dario Neri. Kinetically-controlled release of blocking molecules for the targeted enhancement of therapeutic activity in antibody-cytokine fusion proteins [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 5563.