Signal conversion as tumor micro environment (TME) specifically activated cytokine

Targeted cytokine delivery has been gaining popularity in cancer immunotherapy since systemic recombinant cytokine treatment has not been successful due to low response rate and systemic toxicities in the clinical studies. In order to address these issues, we propose a new concept that cytokine signal is specifically activated at tumor-micro-environment (TME) by delivering two protein subunits of heterodimeric cytokine fused with a tumor targeting antibody respectively to TME and by bridging the two subunits into active heterodimeric form. Interleukin-12 (IL-12) is one of the major cytokines which can induce immune activation. IL-12 consists of two protein subunits which are p35 and p40. IL-12 signaling is initiated when it forms as the heterodimeric protein and binds to IL-12 receptor complex. We made fusion proteins of both IL-12p35 and IL-12p40 targeting specific tumor associated antigens (TAAs) and demonstrated the formation of bioactive IL12p70 with TME targeting antibody toward both p35 and p40 to form as the active molecule. We describe our concept validation in an in vitro based functional assay.