Safety pharmacology, toxicology and pharmacokinetic assessment of recombinant human omega-interferon produced from CHO-SS cells.

Human omega-interferon (IFN-omega) has been shown to be well-tolerated in man and to induce reductions of hepatitis C virus RNA levels in a series of human clinical trials. Here we provide an overview of our preclinical safety evaluation of the fully-glycosylated human IFN-omega produced from CHO-SS cells that is currently being evaluated clinically. IFN-omega was not associated with any biologically-relevant adverse effects in a series of 10 safety pharmacology experiments, in the Ames mutagenicity test, in the micronucleus test, or in intraarterial, intravenous, paravenous or subcutaneous local tolerance studies. Acute, subacute, subchronic and reproductive toxicity studies performed in cynomolgus monkeys and rats showed a toxicity profile similar to that of human alpha interferon (IFN-alpha). Except for the acute (single-dose) toxicology study, all of the other toxicity studies showed evidence for the formation of anti-IFN-omega antibodies over time in the animals. These antibodies were found to neutralize IFN-omega antiviral activity in vitro in a dose-dependent manner. The average pharmacokinetic parameters following a single subcutaneous dose of IFN-omega in rabbits, rats and monkeys were determined and found to be similar to that of human IFN-alpha. These findings demonstrate that IFN-omega has a safety profile consistent with that required for its use in man. IFN-omega might be beneficial for the treatment of patients infected with hepatitis C virus who fail to respond to IFN-alpha or as a first-line treatment option.