Hepatitis B Virus Genotypes E, F, G, and H Appear Responsive to Treatment with Interferon Alpha

Patients with hepatitis B virus (HBV) genotypes E, F, G, and H appear to be sensitive to interferon alpha, as well as nucleoside/nucleotide analogs, although sustained virological response rates did not exceed 50%, according to a report in the October 2009 issue of the Journal of Medical Virology.

It is well known that hepatitis C virus (HCV) genotypes respond very differently to interferon-based therapy, but the effect of HBV genotype has been less extensively studied. This is especially true for more recently identified genotypes E through H, which are most common outside the U.S., Western Europe, and Asia, where most hepatitis B research is conducted.

In the present study, an international team of investigators evaluated 49 patients with HBV genotypes E, F, G, or H, as determined by direct sequencing of the HBV S gene. Just over half (55%) were of African descent, 43% were Caucasian, and 2% were Asian.

The distribution of HBV genotypes was as follows:

	Genotype E: 61.2% (n = 30);
	Genotype F: 8.2% (n = 4);
	Genotype H: 10.2% (n = 5);
	Genotype G: 20.4% (n = 10), including 4 coinfected with G/A and 3 with G/C.

About half the participants (n = 23) received interferon alpha, 12 received nucleoside/nucleotide analogs such as lamivudine (Epivir-HBV) or adefovir (Hepsera), and 14 remained untreated.

Sustained virological response (SVR) among interferon-treated patients was defined as HBV DNA suppression < 4000 IU/mL and alanine aminotransferase (ALT) normalization 6 months after completion of treatment. Virological response with nucleoside/nucleotide analogs was assumed if a patient achieved HBV DNA < 200 IU/mL after 48 weeks of treatment.

Results

	Among patients treated with interferon, the overall end-of-treatment response rate was 70% (16 of 23 patients).
	The overall sustained virological response rate was 35% (8 of 23 patients).
	By genotype, SVR rates were as follows:
	- Genotype E: 36% (5 of 14 patients); - Genotype F or H: 50% (2 of 4 patients); - Genotype G: 20% (1 of 5 patients).
	Among patients treated with nucleoside/nucleotide analogs, 67% overall achieved virological suppression at week 48.

"According to the present preliminary data HBV genotypes E, F, and H appear to be sensitive to interferon-alpha," the study authors concluded. "Lower rates of response to interferon-alpha in patients with HBV genotype G might be related to the frequent occurrence of double infection."

Klinik für Gastroenterologie, Hepatologie und Infektiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany; Institut für Virologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany; Divsion of Gastroenterology and Hepatology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China; Service d'Hépatologie, Hôpital Beaujon, Clichy Cedex, France; Medizinische Klinik m.S. Hepatologie und Gastroenterologie, Charité, Berlin, Germany.

10/16/09

Reference
A Erhardt, T Göbel, A Ludwig, and others. Response to antiviral treatment in patients infected with hepatitis B virus genotypes E-H. Journal of Medical Virology 81(10): 1716-1720. October 2009. (Abstract).