although not known if this applies to hbv because studied on hcv only it makes sense that lack of any side effect reflects less cytokine activity and so lower response to intf
AASLD: Fever Signals Responsiveness to Pegylated Interferon for Hepatitis C
Details Category: HCV Treatment Published on Tuesday, 27 December 2011 00:00 Written by Liz Highleyman
People who have an increase in body temperature soon after starting interferon-based therapy for chronic hepatitis C virus (HCV) infection are more likely to experience early virological response, according to a presentation at the American Association for the Study of Liver Disease (AASLD) Liver Meeting last month in San Francisco.
Rather than directly targeting HCV, interferon works by stimulating the body's immune response. This can lead to a variety of flu-like symptoms including fever, loss of appetite, and muscle aches. But it is not known how these side effects relate to antiviral activity.
Hwalih Hanand colleagues from the National Institutes of Health evaluated whether temperature changes after starting interferon reflect responsiveness to pegylated interferon, as assessed by viral kinetics, serum cytokine levels, and treatment response.
The study included 60 previously untreated chronic hepatitis C patients who started standard therapy using pegylated interferon plus ribavirin. Half were men, nearly 60% were white, about 20% each were black and Asian, and the mean age was 52 years. A majority (57%) had difficult-to-treat HCV genotype 1, one-third had genotypes 2 or 3, and 10% had genotypes 4, 5, or 6.
The researchers measured body temperature with an oral thermometer before the first injection of pegylated interferon and at 8, 16, and 24 hours thereafter, and determined the maximum temperature increase from baseline within the first 24 hours, or Tmax.
Serum HCV viral load was measured at baseline, at 6, 24, 48, and 72 hours, and then weekly for the first 4 weeks of treatment, and used to calculate the first and second phase slope of HCV decline. Levels of interferon gamma-inducible protein 10 (IP-10) were also assessed for a subset of patients at baseline and at 6 and 24 hours after treatment initiation.
The average maximum temperature increase after starting interferon was 1.1°C.
The average peak temperature was 37.9°C, and 33% of patients experienced fevers above 38.0°C within 24 hours.
Overall, 42% of participants experienced rapid virological response (RVR) at week 4, 83% showed early virological response (EVR) at week 12, and 38% achieved sustained virological response (SVR) at 24 weeks after the end of treatment.
There was a strong and significant positive correlation between maximum temperature (Tmax) and the first phase of viral decline.
However, Tmax did not correlate with the second phase of viral decline.
The correlation between Tmax and first phase viral decline was similar for people with genotype 1 and those with genotypes 2 or 3, with no difference in average Tmax across viral genotypes.
There was a significant positive correlation between Tmax and IP-10 induction at 6 and 24 hours.
Tmax was significantly higher on average for participants with the favorable IL28B rs129790860 "CC" gene pattern -- a known predictor of treatment response -- compared to those with the unfavorable "CT" or "TT" patterns (1.43 vs 0.84°C, respectively).
Tmax predicted RVR at week 4 and EVR at week 12, though the correlation was weak.
"Temperature increase after the initial injection of pegylated interferon is closely associated with interferon responsiveness, as reflected by the correlation with serum IP-10 increase, virological decline, and IL28B genotype," the researchers concluded. "The lack of difference between genotypes pinpoints its association with host-responsiveness factors."
As an easily measurable marker, they suggested, temperature "may be incorporated as a surrogate of more expensive and elaborate tests in future models of responsiveness to interferon-based treatment."