My first round of HCV therapy didn't work. Will re-treatment be effective?
According to the U.S. Food and Drug Administration, there are three categories of treatment-experienced people living with HCV. Generally speaking, these are people who were treated for HCV in the past but did not achieve an SVR as a result of therapy (or stopped treatment because of side effects).
Responder Relapser: A person with an undetectable HCV viral load at end of treatment with a pegylated interferon-based regimen, but who has a detectable viral load within 24 weeks after stopping treatment.
Partial Responder: A person who sees his or her HCV viral load decrease by at least 2 log (at least 99 percent) by week 12 of treatment, but does not achieve an undetectable viral load at the end of treatment with pegylated interferon plus ribavirin.
Null Responder: A person who does not see his or her HCV viral load decrease by at least 2 log (at least 99 percent) by week 12 of pegylated interferon/ribavirin treatment.
In addition, there are people who stopped HCV treatment because of severe side effects, and people who do not know their HCV treatment history.
Relapsers. HCV protease inhibitors have dramatically improved cure rates among people who relapsed, because it is clear that pegylated interferon and ribavirin work almost well enough on their own. These drugs are already doing some heavy lifting; adding a protease inhibitor can seal the deal. Many people with a history of relapse may not require a full 48 weeks of treatment, depending on their response to retreatment at 4, 8 and 12 weeks.
With Victrelis, 68 to 74 percent of people who relapsed were cured by retreatment (versus 20 percent for pegylated interferon and ribavirin). Adding Incivek boosted cure rates from 24 percent (with pegylated interferon and ribavirin) up to 83 to 88 percent.
Partial Responders. People with a history of partial response to HCV treatment can be cured if a protease inhibitor is added to pegylated interferon and ribavirin. Adding Victrelis to pegylated interferon boosted cure rates up to 51 percent after 48 weeks (versus 29 percent for pegylated interferon and ribavirin). With Incivek, 54 to 59 percent of prior partial responders were cured after 48 weeks of treatment (versus 15 percent for pegylated interferon and ribavirin).
Null Responders. People with a history of null response to hepatitis C treatment are less likely to be cured by adding a protease inhibitor to pegylated interferon, especially if they have cirrhosis. After 48 weeks of treatment with Incivek plus pegylated interferon and ribavirin, only 14 percent of null responders with cirrhosis were cured, versus ten percent for pegylated interferon and ribavirin alone. Cure rates increased to 29 to 33 percent among null responders with less liver damage, versus five percent for pegylated interferon and ribavirin alone.
The good news is that adding a second antiviral drug that targets a different part of the hepatitis C viral lifecycle may be an effective treatment strategy for null responders. This approach is currently being explored in clinical trials.