Dear Editor:
It is not clear to me in my
reading as to when during the course of therapy with peg interferon and ribavirin
that a HCV by PCR titre should be obtained to assess EVR as a guide to
continued therapy for type I or Type 2-3. I have read suggested time intervals
of 4, 12 and 24 weeks for type I. Any suggestions?
FM
Dear FM:
Thank you for your inquiry.
The pivotal studies of peginterferon alfa-2a from Roche and peginterferon
alfa-2b from Schering both show that 12 weeks, or 3 months, is the time to
assess the early virological response (EVR) while receiving therapy. If the HCV
RNA titer has not decreased by 2 logs or become undetectable, virtually no
patients will go on to develop a sustained virological response (SVR) - 3% in
the Roche study and 0% in the Schering study. This rule pertains to genotype 1
patients. Since 97% of genotypes 2 and 3 patients have an EVR, it is doubtful
if HCV RNA should even be checked at 3 months of therapy; these patients might
simply be treated for 6 months.