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Isatoribine

Descrpition of isatoribine: isatoribine (also known as immunosine, or 7-thia-8-oxoguanosine) is a novel guanosine analogue showing immunostimulatory activity both in vivo and in vitro. This compound acts on different components of the immune system including B cells, natural killer (NK) cells and antigen-presenting cells (APC). It was found that immunosine significantly stimulates proliferation of T cells. The effect was dose-dependent and also depended on concentrations of specific stimulators. Maximal stimulation was seen using 250 microM immunosine. The stimulatory effect of immunosine on lymphocyte proliferation triggered by Concanavalin A (Con A) correlated with increased interleukin 2 (IL-2) production and upregulation of the IL-2 receptor alpha (IL-2Ralpha) expression. (source: Fundam Clin Pharmacol. 2000 May-Jun;14(3):209-17.)

Current developer:  Anadys Pharmaceuticals, Inc.

Isatoribine is currently developed by Anadys Pharmaceuticals, Inc. According to Anadys's website, isatoribine  is a nucleoside analog currently in evaluating in ongoing clinical trials for the treatment of HCV infections. Isatoribine represents one of a new class of drugs being developed by Anadys to regulate innate immunity, combat HCV infection, and overcome limitations of current anti-HCV therapies. Anadys believes isatoribine interacts with a specific receptor, Toll-like receptor 7, or TLR7, that is present on certain immune system cells. Although results of initial clinical trials may not be predictive of future results, interim results of the Phase 1B clinical trial show that isatoribine is biologically active in adults with chronic HCV infection and results from dosing a cohort of six HCV infected patients with 800mg of isatoribine showed a statistically significant reduction of viral load (p=0.03) at the end of one week, with a median change in viral load from baseline of -0.94 log10 units. Anadys is currently enrolling patients for an isatoribine Phase I/II study.

Current developer:  Anadys Pharmaceuticals, Inc.

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