According to the U.S. Food and Drug Administration, there are three categories of treatment-experienced people who have completed therapy but are still living with HCV. They include:
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, some people stop HCV treatment because of severe side effects and others do not know their HCV treatment history.
Unfortunately, when it came to researching people with genotype 1 of the virus, the Sovaldi clinical trials only included those who were "treatment naive" (meaning they were being treated for the first time). However, some Solvaldi research did include those with genotypes 2 and 3 who had failed a previous treatment.
In studies of Sovaldi and ribavirin given to genotype 2 and 3 relapsers and "non-responders" (which includes both partial and null responders), there was no significant difference in response rates between the relapsers and the non-responders. In one study, 90 percent of previously treated study participants who had genotype 2 were cured after 12 weeks of treatment, compared with 97 percent of the never-treated participants.