The first-proof-of-concept for a DNA-based therapeutic vaccination against chronic hepatitis C was announced at EASL 2009, the Annual Meeting of the European Association for the Study of the Liver in Copenhagen, Denmark.

In the first clinical trial of a therapeutic vaccination using naked DNA delivered by in vivo electroporation (EP), antiviral effects were shown in patients with hepatitis C (HCV). Researchers hope that this will encourage further clinical development. The data also provide further evidence for the antiviral role of the HCV-specific T cell response.

It is estimated that some 3% of the world's population is infected with HCV. In industrialised countries, hepatitis C accounts for 70% of chronic hepatitis cases. One of the main concerns is that HCV infection remains asymptomatic until advanced stages of the disease.

Clearance of HCV infection correlates with activation of the host T cell response. Therefore, in this study, researchers developed a T cell vaccine based on a codon-optimised HCV non-structural (NS) 3/4A DNA-gene expressed under the control of the cytomegalovirus immediate-early promoter (ChronVac-C®) delivered by in vivo electroporation (EP). A first phase I/IIa clinical trial in HCV infected patients is currently ongoing.

Professor Matti Sallberg of Laboratory Medicine, the Karolinska Institutet, Stockholm, Sweden, who led the study, said: "In 50-80% of adult cases, the immune system fails to eliminate the HCV virus and the disease becomes chronic. Given that only about 50% of HCV infected persons are diagnosed in most developed countries and that two-thirds need to undergo antiviral treatment, this new vaccination has huge implications in terms of the future management of this widespread disease."

In this study, a volume of 0.5 ml saline containing ChronVac-C® DNA was injected at 1 cm depth in the deltoid muscle. This was followed by two 60ms electrical pulses administered using a 1.5 cm four-electrode array (Medpulser DDS; Inovio, CA, US). The study aims were safety, immunogenicity, and effects on the viral load. Twelve treatment naive patients infected with HCV genotype 1 and a viral load 10 weeks. Of these, three had activations of the HCV-specific T cell responses at the time of the reductions in the viral load.

Source:
Camilla Dormer
European Association for the Study of the Liver