Predicting the response to treatment
DAAs are so effective that very few factors reduce the chance of a cure.
However, early treatment response is still a good predictor of success and more severe liver diseases is sometimes more difficult to treatment.
How is the response to HCV treatment measured?
Several medical terms and abbreviations are used to describe responses to HCV treatment (see Table 3).
The most important of these is SVR-12 because this defines if HCV is cured.
Table 3: Terms used to describe responses to HCV treatment
|Abb.||Term||Meaning and comment|
|SVR-12||Sustained viral response 12 weeks after the end of treatment.||SVR-12 means having an undetectable HCV viral load 12 weeks after the end of treatment. This is considered a cure.|
|VBT||Viral breakthrough.||When viral load became undetectable during HCV treatment, but then becomes detectable while still on treatment.|
|Relapse||Relapse or relapser||When viral load becomes undetectable on treatment, but rebounds after it is stopped.|
|Treatment-experienced||Someone who has already used one or more HCV treatments.||With DAAs, treatment-experienced is defined by the previous type of treatment, i.e. protease inhibitor experienced.|
Most of the following factors predicted how well HCV peginterferon and ribavirin worked. Most of these are no longer important with DAAs.
- Having an undetectable HCV viral load after four weeks of treatment.
- HCV genotype and subtype.
- HCV treatment is less effective for people with cirrhosis – though DAAs are still very effective.
- Genetics and race, although these are less important when DAAs are used with or instead of peginterferon (see box).
- HCV viral load is much less important with DAAs.
- HIV status. Although HCV treatment used to be less effective for HIV positive people, cure rates are similar when DAAs are used with or instead of peginterferon.
- Adherence. Not missing doses is especially important with HCV protease inhibitors and other DAAs.
- Effectively managing side effects.
As with HIV, starting treatment is the only way to know how well you will respond.
HCV, genetics and race
The interleukin-28B (IL28B) gene affects how well peginterferon and ribavirin work. This factor is not important with modern HCV drugs (DAAs).
Of the three possible IL28B genotypes (CC, CT or TT), people with CC have a stronger immune response to this treatment.
Having the CC genotype has also been linked to a higher chance of clearing HCV without treatment.
African Americans and people of African ancestry are more likely to have non-CC genotypes. This explains – in part – why peginterferon-based treatment is less effective for African Americans. Asian people and people with Asian ancestory are most likely to have the IL28B CC genotype.
IL28B genotype is less important with some of the new DAAs, especially when they are used without peginterferon.
UK guidelines do not recommend routinely testing for IL28B.
Last updated: 17 August 2017.