Last month, Vertex Pharmaceuticals announced the interim results from an ongoing Phase II study to evaluate the safety and tolerability of the company’s protease inhibitor (PI) therapy Incivek™ (telaprevir), when taken with the standard combination therapy of pegylated-interferon and ribavirin. The results were reported at the Conference on Retroviruses and Opportunistic Infections in Seattle, March 5-8.The study included 60 individuals co-infected with genotype 1 hepatitis C virus (HCV) and the human immunodeficiency virus (HIV). Genotype 1 accounts for approximately 70% of HCV patients. All enrolled patients were new to HCV therapy.
First approved by the U.S. Food and Drug Administration in May 2011, PIs, such as Incivek™ represent direct-acting antivirals, a new class of HCV drugs that prevent viral enzymes from replicating. Success is measured by patients’ ability to “clear” the virus by achieving a sustained virological response (SVR) for at least six months after completing therapy. The inclusion of a protease inhibitor increases the likelihood that a patient with HCV genotype 1 will reach SVR in up to half the time–24 weeks vs. 48 weeks.
Although these PIs are not currently approved for use in co-infected people, interim data have shown that these patients had a higher virological response when a PI was added to pegylated interferon/ribavirin and that adverse events were no different than patients with HCV alone. Physicians are interested in the possible off-label use of PIs in co-infected patients for several reasons: their liver disease progression is more accelerated; peginterferon/ribavirin is less effective for them; and liver transplantation is neither highly successful nor widely available to them.
The study data showed that 28 of 38 (74%) patients with genotype 1 HCV (74%) who were treated with Incivek™ and peginterferon/ribavirin had undetectable levels of the virus 12 weeks after the end of all study treatment, compared to 10 of 22 (45%) patients treated only with interferon. Commonly prescribed HIV treatment therapies including such drugs as Atripla® and Reyataz® were well tolerated when taken along with the HCV therapies. Comparable changes in CD4 counts were observed between the treatment groups, and no HIV viral load breakthroughs were reported in either treatment group during the study. The most common side-effects in the Incivek™ arm of the study included fatigue, pruritis (itching), headache, nausea and rash.
The study was further broken down into Part A and Part B. Part A included individuals who were not currently being treated with antiretroviral therapy (ART) for HIV infection. Part B evaluated those taking an Atripla- or Reyataz-based regimen for HIV. Interim data showed that 26 of 38 (68%) patients treated with Incivek™ combination therapy had a rapid viral response (RVR, undetectable HCV at week 4 of treatment) compared to none of the patients who received interferon/ribavirin alone.
Robert Kauffman, senior vice president and chief medical officer of Vertex, said the new Incivek data are important as the company works toward its goal of helping cure more people with HCV. “We’re actively enrolling co-infected patients in a Phase III study and expect that data from this study will be included in a submission for a supplemental approval of INCIVEK.”
Source: Pharmaceutical Business Review (online), March 7, 2012