RVR (Rapid virological response)= No virus detected at week 4.
eRVR(Extended rapid virological response) = No virus detected at week 4 and week 12.
EVR (Early Virological Response) = 2 log drop of HCV RNA after 12 weeks.
cEVR = Complete Early Virological Response — No virus detected after 12 Weeks.
SVR12 (Sustained virological response)12 = No virus detected at 12 weeks after completion of treatment.
SVR24 = No virus detected at 24 weeks after completion of treatment
Null response - Failure to reduce HCV RNA by at least 2 logs10 (100 times) after 12 weeks of prior treatment, which is the currently recommended Food and Drug Administration (FDA) definition for clinical trials of investigational hepatitis C treatments.
Partial response - At least a 2-log10 (100-times) drop in HCV RNA, but inability to fully remove the virus from the blood by week 24.
Breakthrough - After dropping to undetectable levels, HCV RNA is detected again in blood during treatment.
Relapse - After dropping to undetectable levels, HCV RNA is detected again in blood after treatment ends.
SVR-Sustained Virological Response, UND-Undetected.
Are you sure you don't mean UND ? Undetectable.
http://www.medhelp.org/health_pages/Hepatitis/Hepatitis-C-Acronyms-Abbreviations/show/3?cid=64