Modest" Results With Nitazoxanide for HCV Genotype 1 Nonresponders
April 27, 2010 (Vienna, Austria) — Adding nitazoxanide (Alinia, Romark Laboratories) to standard therapy helped boost sustained virologic response (SVR) rates for some hepatitis C virus (HCV) genotype 1 patients who previously failed to respond to standard therapy alone, researchers report.
But the addition of the drug led to only "modest" success, they said in a presentation here at the European Association for the Study of the Liver 45th Annual Meeting.
Only 3 of 40 patients (7%) went on to achieve SVR, lead investigator Mitchell Shiffman, MD, professor of medicine and chief of hepatology at Virginia Commonwealth University in Richmond , told meeting attendees.
Nitazoxanide, the first in a new class of antiviral drugs known as thiazolides, has been shown in vitro to have activity against influenza, HCV, and rotavirus.
It has been shown to be a potent inhibitor of HCV in replicon systems and it has the advantage of not giving rise to HCV-resistant mutations in HCV replicons, the researchers said.
It has performed well alongside interferon and direct-acting antiviral drugs. It has also demonstrated effectiveness against telaprevir-resistant and 2′-c-methylcytidine-resistant HCV strains.
The antiviral method of action of nitazoxanide is still being researched, but it is believed that it inhibits viral glycolproteins at the posttranslation level. This would prevent the final assembly of the virus before it can exit the cell to infect another cell, Dr. Shiffman explained.
Monotherapy with nitazoxanide has been shown, in a phase 2 study, to yield a 17% SVR rate for chronic HCV genotype 4 patients, he continued.
Two phase 2 studies of nitazoxanide plus peginterferon, with or without ribavirin, yielded SVR rates of 79% and 80% in treatment-naïve genotype 4 patients, and 25% and 8%, respectively, in treatment-experienced patients.
The study involved 64 patients with chronic HCV genotype 1 — and previous nonresponse to peginterferon plus ribavirin — to either nitazoxanide (n = 42) or placebo (n= 22) twice daily for 4 weeks, followed by the continuation of nitazoxanide or placebo plus peginterferon alfa-2a 180 mg weekly and weight-based ribavirin (1000 to 1200 mg/d) for 48 weeks. Average age was 54 years.
The 6 patients who achieved end-of-treatment response after 28 weeks (3 relapsed) saw their HCV RNA levels start to fall after 8 weeks.
The 3 patients with sustained SVR all had achieved a complete early virologic response, and 2 of those had achieved a rapid virologic response.
They all had high baseline HCV RNA levels (greater than 800,000 IU/mL). Only 1 patient had advanced hepatic fibrosis.
None of the patients in the control group, treated with standard therapy and placebo, attained SVR.
The most common adverse events were weakness and diarrhea, which were also common with standard therapy alone. No adverse events led to treatment discontinuation.
Although he called the SVR rates "modest" in these patients, Dr. Shiffman said more work should be done to explore the value of nitazoxanide in certain patients.
"Further studies of nitazoxanide plus peginterferon and ribavirin are therefore warranted in patients who have failed therapy but who exhibited a partial response to peginterferon plus ribavirin or in relapse patients," he said.
Special attention should be paid to dosage, he added.
"What is unknown is the exact dose of nitazoxanide that may be most effective — there was no dose study ever done for hepatitis C," he said. "Additional development of a controlled-release nitazoxanide formulation may improve SVR rates in this patient population."
Xavier Forns, MD, from the Hospital Clinic at the University of Barcelona in Spain , said he suspects nitazoxanide's impact will be minimal for HCV patients.
"It's a wonderful study but the numbers are very small," he said. "I don't think with these data you can really make a big thing of it."
"It's cheap and it's safe and that's good news," but said, adding, "I think they have to show better efficacy."
The study was paid for by Romark Laboratories. Dr. Shiffman reports receiving consulting fees from Romark. Dr. Forns has disclosed no relevant financial relationships.
European Association for the Study of the Liver (EASL) 45th Annual Meeting. Presented April 17, 2010.