sIL-6R (Tosoh)

Over one third of patients who have undergone oral squamous cell carcinoma (OSCC) surgical resections develop life-threatening and often untreatable recurrences. A variety of drugs, intended for management of recurrent or disseminated cancers, were designed to exploit cancer cells' reliance upon overexpressed receptors and gratuitous signaling. Despite their conceptual promise, clinical trials showed these agents lacked efficacy and were often toxic. These findings are consistent with evasion of pathway-targeted treatments via extensive signaling redundancies and compensatory mechanisms common to cancers. Optimal secondary OSCC chemoprevention requires long-term efficacy with multifaceted, nontoxic agents. Accordingly, this study evaluated the abilities of three complementary chemopreventives, that is, the vitamin A derivative fenretinide (4-HPR, induces apoptosis and differentiation, inhibits signaling proteins, and invasion), the estrogen metabolite 2-methoxyestradiol (2-ME, apoptosis-inducing, antiangiogenic), and the humanized mAb to the IL6R receptor tocilizumab (TOC, reduces IL6 signaling) to suppress OSCC gratuitous signaling and tumorigenesis. Modeling studies demonstrated 4-HPR's high-affinity binding at STAT3′s dimerization site and c-Abl and c-Src ATP-binding kinase sites. Although individual agents suppressed cancer-promoting pathways including STAT3 phosphorylation, STAT3-DNA binding, and production of the trans-signaling enabling sIL6R, maximal chemopreventive effects were observed with agent combinations. OSCC tumor xenograft studies showed that locally delivered TOC, TOC+4-HPR, and TOC+4-HPR+2-ME treatments all prevented significant tumor growth. Notably, the TOC+4-HPR+2-ME treatment resulted in the smallest overall increase in tumor volume. The selected agents use diverse mechanisms to disrupt tumorigenesis at multiple venues, that is, intracellular, tumor cell-ECM, and tumor microenvironment; beneficial qualities for secondary chemopreventives. Cancer Prev Res; 10(1); 76–88. ©2016 AACR.

IL-6 is a 26-kDa protein cytokine with pleiotropic activities in both hematopoietic and immune systems. It is one of the major mediators of the acute phase inflammatory response. Recently it has been demonstrated that pharmacological doses of human recombinant IL-6 (rhIL-6) inhibit certain murine tumors as well as stimulate thrombopoiesis in mice, dogs, nonhuman primates, and humans. The purpose of our study was to evaluate the effects and toxicity of rhIL-6 administration in nonhuman primates with particular reference to subject age. We treated 10 female monkeys of two age groups (midle-aged and old) with rhIL-6 (15 micrograms/kg/day) for 28 days. The monkeys were observed to be somewhat lethargic and lost an average of 10% of their body weights. The white blood cell count rose transiently whereas the levels of hemoglobin and hematocrit fell significantly and remained depressed for the same period. Importantly, platelet count rose and remained elevated for the duration of treatments. Serum alkaline phosphatase levels increase significantly and certain parameters of clinical immune competence were altered by IL-6 treatment. Treatment effects were similar in both age groups, but the changes in immune functions were different between the midle-aged and old monkeys. We observed a pattern in which the middle-aged group had a significant decrease in immune functions as a result of IL-6 administration and recovered to pretreatment level despite continuous treatment, whereas the old monkeys had a more protracted but less significant decline in these same immune functions during the trial.(ABSTRACT TRUNCATED AT 250 WORDS)