Pegylated Interferon Alfa-2b Plus Ribavirin in Chronic Hepatitis B and Delta

Recombinant IFN alfa possesses anti-viral and immunomodulatory effects and has been shown to be effective in chronic hepatitis B [Davis et al. 1989; Bisceclie et al, 1989]. Interferon alfa is also one of the approved treatments for chronic hepatitis B. Administration of IFN alfa-2b to adults leads to disappearance of HBV DNA with or without HBeAg seroconversion in 30-50% of patients, which is two to three times above the rate of yearly spontaneous HBeAg seroconversion (10-15%). Normalization of serum ALT occurs in most cases. Loss of HBsAg is observed in 10-15% of Caucasian patients during the prolonged post-treatment follow-up period. Recently, studies suggested that a higher proportion of patients receiving pegylated IFN could achieve HBeAg seroconversion and control of HBV replication [Marcellin et al, 2004; Lau et al, 2004; Jensen et al, 2004].

RBV is another antiviral nucleotide analogue with few adverse effects [Sidwell et al, 1972; Patterson et al, 1990]. RBV alone can modestly inhibit HDV or HBV replication [Choi et al, 1989]. The beneficial effect of combined IFN plus RBV in the treatment of chronic hepatitis B has also been shown in previous studies [Cotonat et al, 2000]. Why RBV can greatly enhance the treatment efficacy is not clear. It had been shown that ribavirin could inhibit interleukin-4, an inhibitor of cytotoxic T lymphocyte activity, and preserves the interleukin-2 and gamma IFN activities. Other studies revealed that the enhanced efficacy was associated with HBV- or other virus-specific type 1 cytokine-mediated T helper cell responses [Cramp et al, 2000; Tam et al, 1999; Hultgren et al, 1998; Fang et al, 2002; Fang et al, 2000; Rico et al, 2001]. Thus, the combination therapy may augment virus-specific cytotoxic T lymphocytes and non-specific immune response, and effectively shift the immune responses to the more potent antiviral type 1 T-helper profile [Hultgren et al, 1998].

HDV, like HCV, is a RNA virus. Indeed, RBV had also been shown to be active against HDV replication in cell cultures [Choi et al, 1989]. The investigators therefore hypothesize that pegylated IFN alfa-2b in combination with RBV can yield an efficacy in chronic hepatitis D patients who are dually infected by HBV. The purpose of this protocol is to test this hypothesis. A previous study found that high-dose IFN may improve the efficacy for chronic hepatitis D patients. Another pilot study using IFN alfa plus RBV also demonstrated that the seroclearance of HCV RNA was not affected by HBV coinfection [Liu et al, 2003]. The investigators thus use pegylated IFN alfa-2b in combination with RBV for the treatment of patients with dual chronic HDV and HBV infection.

The treatment choice for chronic hepatitis D was not clarified till now. In this proposal, the dosage and duration for the combination regimen are decided mainly by the experience from the treatment of chronic hepatitis B and chronic hepatitis C.

The investigators recent study using ribavirin and interferon (IFN) combination therapy for dual chronic hepatitis B and C suggested that combining ribavirin 1,200 mg daily for 6 months, together with 6 million units (MU) IFN-alpha 2a thrice weekly for 12 weeks and then 3 MU for another 12 weeks was effective for the clearance of HCV RNA [Liu et al, 2003]. Twenty-four patients with chronic hepatitis seropositive for both hepatitis B surface antigen and antibody to HCV received ribavirin 1,200 mg daily for 6 months, together with 6 million units (MU) IFN-alpha 2a thrice weekly for 12 weeks and then 3 MU for another 12 weeks. The serum HCV clearance rate was 43% 24 weeks posttreatment. The serum ALT normalization rate was 43% 24 weeks posttreatment. In hepatitis B and C dually infected patients, combination IFN with ribavirin can achieve a sustained HCV clearance rate comparable with hepatitis C alone. Furthermore, a previous study revealed that a 12-week RBV therapy was not effective for patients with chronic hepatitis B [Kakumu et al, 1993]. Therefore, a 24-week course of combination therapy pegylated IFN+RBV will be used.

Increased RBV dosage has been considered a contributory factor to the better efficacy in treating refractory genotype HCV. For example, recent studies suggested that using RBV 800 mg daily is adequate to treat HCV genotype non-1 while the standard dosage of RBV is required to treat HCV genotype 1 [NIH 2002]. The investigators thus propose to use RBV 1000-1200 mg daily according to the body weight of the patient.