Hepatitis C treatment: evaluating response

How response to HCV treatment is measured

The response to hepatitis C (HCV) treatment is measured by HCV viral load tests at different times.

SVR (sustained virological response)

An SVR means that HCV is not detectable in blood six months after completing treatment. Many experts think of SVR as a cure.

SVR rates are usually the most important results to look for from a clinical trial.

EVR (early virological response)

An EVR means that the hepatitis C viral load has dropped by 99% (2 logs), or is undetectable after 12 weeks of treatment.

Someone who does not have an EVR only has a very low chance of getting an SVR (less than one-in-twenty). Usually, people choose to stop hepatitis C treatment if they do not have an EVR.

Some people may switch to a lower dose of PEG interferon to prevent HCV progression with maintenance therapy at this point.

ETR (end of treatment response)

An end-of-treatment response means that hepatitis C virus can not be found using an HCV viral load test at completion of therapy. Some people with an ETR will see HCV viral load return, so ETR is not a reliable predictor of long-term response.

RVR (rapid virological response)

An undetectable HCV viral load after four weeks is called a rapid virological response (RVR). If HCV viral load is undetectable, it is a good indication of continuing to have an SVR later. However, RVR is not good at predicting who is unlikely to respond, so treatment should not be stopped if there is no RVR. RVR is currently only used in research.

Relapser

The term relapser refers to someone who has an EVR or ETR, but whose virus rebounded and who didn’t achieve an SVR.

Non-responder

Non-responder is a general term for someone who does not have an EVR, or, if they stay on treatment for 24 weeks, does not ever have a 99% drop or an undetectable HCV RNA while on treatment.