PO-040 Development of a tunable form of interferon alpha for in vivo cancer gene therapy

Abstract

IntroductionThe immune system is a double-edge sword in cancer. On the one hand, it exerts immunosurveillance to eradicate transformed cells that occasionally appear in the body; on the other hand, cancer cells can recruit immune cells endowed with pro-tumorigenic activity.Our lab previously developed a strategy for targeted gene-based delivery of interferon alpha (IFNa) to tumours by tumour infiltrating monocytes/macrophages, which induces robust anti-cancer responses in several experimental models without inducing strong IFN responses in normal tissues as compared to systemic administration of recombinant IFNa. Whereas a sustained output could ensure long-term protection from tumour recurrence, it may raise concerns for long-term side effects, especially in case of cancer eradication.To overcome this issue, we are developing inducible strategies to control the amount of IFNa secreted in the tumour microenvironment.Material and methodsBy fusing a destabilising domain (DD) to a protein of interest (POI) the former can confer its instability to the latter. This destabilisation can be rescued in a reversible and dose dependent manner with the addition of a small molecule specifically binding to the DD. To apply this technology to our strategy we have designed and in vitro tested different fusion proteins of IFNa (DD-IFNa). We also developed improved DD-IFNa with the addition of flexible and/or cleavable linkers and selected them for their capacity to be stabilised in a dose dependent manner in presence of their specific ligand in vitro.Results and discussionsThrough this approach, we have identified effective fusion proteins with low basal activity and high fold induction upon ligand treatment. These novel tunable forms of IFNa are functional and their specific activity are comparable to the wild type cytokine in inducing IFN responsive genes.Based on these promising in vitro results we are now translating these new platforms in vivo to test their efficacy in inducing anti-tumour responses in melanoma, colon and glioma models of cancer.ConclusionIn the perspective of clinical translation our approach can be used in the future to switch on/off the levels of IFNa in a tunable and personalised fashion for cancer eradication.