Early Study Shows HCV Vaccine Works

Preliminary data show an experimental therapeutic vaccine against hepatitis C virus boosted response rates by 12 percent compared with standard HCV treatment of ribavirin and pegylated interferon, researchers reported at the annual meeting of the American Association for the Study of Liver Diseases in Boston.

Paul Pokros, MD, of the Scripps Clinic in La Jolla, Calif., said the Phase II trial of 133 patients included those who were treatment-naive and those who had not responded to standard treatment. Results in both subgroups were similar to the overall outcome but did not reach statistical significance compared with standard treatment. However, the findings are enough to warrant continued development of GI-5005, a recombinant, inactivated yeast that expresses hepatitis antigens.

GI-5005 generated an immune response similar to that seen among patients who are able to clear HCV without medication -- a modest response to the viral envelope proteins and a robust response to the nonstructural proteins NS3 and NS5.

Study patients randomized to receive the vaccine were given five weekly doses of GI-5005, delivered subcutaneously, followed by two monthly doses. They then received the vaccine on a monthly basis along with standard treatment. The control group of 65 participants received only standard treatment. In both groups, treatment-naive patients were treated for 48 weeks, while previous nonresponders received 72 weeks of treatment.

GI-5005 yielded a 47 percent response rate overall, compared with 35 percent for standard care (P=0.037). Each study arm experienced a 13 percent discontinuation rate due to side effects.

Session moderator Douglas LaBrecque, MD, of the University of Iowa-Iowa City, said a "benign" therapeutic vaccine against HCV could be advantageous, especially "if you could eliminate some of the other medications, either interferon or the small molecules, which have their own side effects." However, acknowledging the study's small size and preliminary data, he added, "all you can say is that it wasn't a total failure."

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