By Liz Highleyman

Serum levels of vitamin B12 may be among the factors that can help predict whether patients with chronic hepatitis C virus (HCV) infection will respond to interferon-based treatment, according to a study by researchers from the Karolinska Institute in Stockholm presented this week at the annual Digestive Disease Week (DDW 2009) meeting in Chicago.

Vitamin B12 is stored in hepatocytes (liver cells) and inhibits HCV RNA translation, the investigators noted as background. However, the association between B12 levels and antiviral treatment outcomes is not clear.

In this retrospective study, the researchers sought to determine whether pretreatment serum B12 levels could predict end-of treatment response (ETR) in 99 treatment-naive chronic hepatitis C patients treated with interferon-based therapy.

Standard treatment, consisting of pegylated interferon plus ribavirin, lasts 48 weeks for patients with HCV genotypes 1 or 4, and 24 weeks for those with easier-to-treat genotypes 2 or 3. HCV relapse may occur after the end of treatment, so a "cure" is usually considered sustained virological response 6 months after completion of therapy.

Results

The mean pretreatment serum B12 level was 331 pmol/L in patients who achieved ETR, significantly higher than the mean 260 pmol/L in non-responders (P = 0.012).

Among participants with serum B12 levels of 360 pmol/L or less, 68.5% achieved ETR and 31.5% were non-responders.

Among patients with serum B12 levels greater than 360 pmol/L, 96.2% achieved ETR and only 1 (3.8%) was a non-responder.

In a multivariate analysis, factors significantly associated with ETR were:

Pretreatment serum B12 > 360 pmol/L vs < 360 pmol/L: odds ratio [OR] 28.6 (P = 0.008);

Advanced fibrosis or cirrhosis (stage F3-F4) vs stage F0-F2: OR 0.29 (P = 0.068).

HCV genotypes 2 or 3 vs genotypes 1, 4, or 5: OR 15.5 (P = 0.0012);

Medication dose reduction vs no reduction: OR 0.21 (P = 0.034);

Use of conventional vs pegylated interferon: OR 0.079 (P = 0.019).

Patient age and sex, however, were not correlated with ETR.

Based on these findings, the investigators concluded, "Serum B12 > 360 pmol/L is independently correlated to ETR in HCV patients treated with interferon and ribavirin. This suggests that B12 is involved in suppression of viral replication during anti- HCV treatment."

Gastroenterology and Hepatology, Karolinska University Hospital, Stockholm, Sweden; Department of Medicine, Karolinska Institutet, Stockholm, Sweden

6/5/09

Reference
P Rosenberg and K Hagen. Serum B12 Levels Predict Response to Treatment with Interferon and Ribavirin in Patients with Chronic HCV Infection. Digestive Disease Week (DDW 2009). Chicago. May 30-June 4, 2009. Abstract M1793.