How response to HCV treatment is measured

The response to 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 6 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.
• SVR-12 is used in research, meaning that a person is still undetectable 12 weeks after finishing treatment. Relapes almost always occur during the first 12 weeks after finishing treatment.

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 1-4% chance of getting an SVR.
• Usually, people choose to stop hepatitis C treatment if they do not have an EVR.

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 areliable predictor of long-term response.

RVR (rapid virological response)

An undetectable HCV RNA 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 (or breakthrough)

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.

How well does treatment work?

Many factors are involved with response to treatment.

This table shows a snapshot of response rates from trials of PEG interferon plus ribavirin.