The studies, Enable 1 and Enable 2, will measure the ability of eltrombopag to raise platelet counts sufficiently enough to enable the initiation of antiviral therapy and to allow sustained antiviral therapy in thrombocytopenic hepatitis C patients. The clinical benefit of eltrombopag will be measured by the proportion of subjects who are able to achieve sustained virological response (SVR).
Enable 1 and Enable 2 are parallel, multi-center, two-part studies that consist of an open-label pre-antiviral treatment phase (Part 1) and a randomized, double-blind, placebo controlled, antiviral treatment phase (Part 2). Both studies will enroll approximately 750 patients with chronic hepatitis C infection (quantifiable HCV RNA) with baseline platelet counts of <75,000/microL. In Part 1 of the study all subjects will receive open-label eltrombopag in increasing doses for up to nine weeks before being randomized to double-blind eltrombopag or matched placebo in combination with antiviral therapy for up to 48 weeks (Part 2). Enable 1 will administer peginterferon alfa-2a plus ribavirin, while Enable 2 will investigate the use of peginterferon alfa-2b plus ribavirin. Eltrombopag is an investigational oral, non-peptide platelet growth factor. The Enable trials will investigate if eltrombopag will allow patients a greater opportunity to maximize the dose and duration of their antiviral therapy, thus improving the likelihood of achieving SVR. John McHutchison, associate director at Duke Clinical Research Institute in Durham, North Carolina, said: "In a previous Phase II study, eltrombopag, compared to placebo, increased platelet counts and allowed more patients to complete the first 12 weeks of antiviral therapy, giving them an opportunity to achieve an SVR. Enable will investigate the effect of eltrombopag over a 12-month treatment period to determine how it may help patients to achieve SVR, which in clinical terms is considered a cure for hepatitis C, as well as better understand any related toxicities or tolerability issues."