Inhibition of Interleukin-6 (IL-6) Signaling and Tumor Growth by a Human Neutralizing Anti-IL-6 Antibody with a Prolonged Half-Life

Interleukin-6 (IL-6) is a pleiotropic cytokine that plays a major role in responding to injury or infection as well as immune response, inflammation, and hematopoiesis. High levels of circulating IL-6 are observed in many tumor types and are associated with poor outcomes. We show that knockdown of IL-6 or IL-6 receptor (IL-6R) inhibits IL-6 signaling and cell viability. In contrast, over-expression of IL-6 enhances tumor growth in vitro and in vivo, thereby supporting the role of IL-6 in tumorigenesis. We developed a human monoclonal antibody against human IL-6 (MEDI5117) that bears Fc mutations (YTE) to extend its half-life. We tested this antibody in several cancer cell lines that secrete high levels of IL-6, soluble IL-6R, and express gp130. High constitutive pSTAT3 (phosphorylated signal transducer and activator of transcription 3) activation is seen in several of these cell lines, suggesting autocrine growth stimulation by IL-6. Treating these cell lines with MEDI5117 effectively blocked phosphorylation of STAT3 and inhibited IL-6-induced cell proliferation. In vivo, MEDI5117 suppressed the growth of multiple cancer xenograft models and specifically modulated IL-6 signaling and downstream gene expression. Combining MEDI5117 with chemotherapy or gefitinib demonstrated significantly enhanced anti-tumor activities in vivo. Taken together, our data suggest that IL-6 signaling contributes to tumor growth, thereby supporting the development of MEDI5117 as a therapy to treat solid tumors.

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Zhong H, Davis A, Ouzounova M, Carrasco RA, Chen C, Breen S, Chang YS, Huang J, Liu Z, Yao Y, Hurt E, Moisan J, Fung M, Tice DA, Clouthier SG, Xiao Z, Wicha MS, Korkaya H, Hollingsworth RE