ATLANTA – A protease inhibitor being investigated in patients co-infected with the hepatitis C virus (HCV) and HIV yielded good early success when combined with pegylated interferon and ribavirin, a researcher said here.

In the so-called STARTVerso 4 trial, 80% of patients had undetectable HCV after 8 weeks of therapy with faldaprevir, according to Douglas Dieterich, MD, of the Mount Sinai School of Medicine in New York City.

That rate was similar to what has been seen in earlier studies among patients with just HCV, Dieterich reported here at the Conference on Retroviruses and Opportunistic Infections.

The results are “enormously encouraging” — even though the regimen still includes interferon – because liver disease is a leading cause of death among HIV-positive people in the U.S., Dieterich told reporters prior to presenting the data. Curing HCV would have an important impact on that statistic, he said.

The current standard care for HCV is interferon and ribavirin, combined with one of two approved protease inhibitors that target the virus specifically – telaprevir (Incivek) and boceprevir (Victrelis), Dieterich noted.

Faldaprevir is seen as a possible replacement for the earlier protease inhibitors, although it is also being tested both with and without interferon in other trials.

But whether it has a role in the future remains unclear, since several interferon-free regimens using so-called direct-acting agents are under study, although none has yet been approved.

Dieterich told MedPage Today that faldaprevir is a “significant advance” on telaprevir and boceprevir: it is dosed once daily, not twice; it has a gentler side-effect profile; and its success rates are better.

“We don’t know exactly when the direct-acting agents will be on the market,” he said, but “in the meantime we’re still stuck seeing patients every day and some of them are really sick and need to be treated.”

Given a choice, he said, he would prefer the new drug over either of the earlier protease inhibitors for such patients.

Dieterich noted he is also principal investigator for another new protease inhibitor, simeprevir, which is also being tested with interferon and ribavirin in HIV/HCV co-infected patients. That drug is expected to be submitted for approval soon, he said.

“These are both very practical compounds, way easier and far superior to boceprevir and telaprevir, so I think we can use them for a while until interferon-free combinations are worked out,” he said.

Indeed, there is likely to be a narrow window in which faldaprevir will be used, commented Juergen Rockstroh, MD, of the University of Bonn, who moderated the session at which Dieterich presented the data.

“For co-infected patients, faldaprevir has very good early response rates,” he told MedPage Today. If the drug were to be licensed soon – perhaps by early 2014 – it would provide an extra option for patients needing immediate therapy.

But, Rockstroh said, “I would only treat patients with it if they really needed it. If they had low fibrosis, I would still wait” for interferon-free regimens.

The STARTVerso 4 trial is a phase III open-label, sponsor-blinded study in both HCV treatment-naïve and relapsed patients with the genotype 1 hepatitis and HIV infection. Dieterich presented 12-week data from a study that for some patients could last as long as 48 weeks.

The complicated study design is testing two doses of faldaprevir – 120 or 240 milligrams a day — combined with interferon and ribavirin, for 24 weeks. At that point, Dieterich said, patients who enjoyed “early treatment success” would be re-randomized to stop therapy or to continue with interferon and ribavirin.

Early treatment success was defined as levels of HCV below the limit of quantification at week four and undetectable levels at week eight. Among the treatment-naïve patients, he reported, 77% had reached the early success milestone, while 88% of the relapsers had done so.

He also reported that at week 12, 82% of the treatment-naïve patients and 91% of the relapsers had undetectable HCV – comparable to the 93% seen among treatment-naïve mono-infected patients.

The most frequent adverse events, Dieterich reported, were nausea, fatigue, diarrhea, headache and asthenia. None of the patients had any loss of HIV suppression.

Source: MedPage Today.