Prophylactic effect of peptide vaccination against hepatocellular carcinoma associated with hepatitis C virus

The purpose of the present study was to investigate the prophylactic effects of peptide vaccination against hepatocellular carcinoma (HCC) associated with hepatitis C virus (HCV). Two different Phase I clinical trials of HCV-derived peptides for 40 HCV-positive patients with chronic hepatitis (CH) and liver cirrhosis (LC) were conducted from November 2003 to November 2008. Among the patients, 39 (33 CH and 6 LC) received prolonged peptide vaccination with a median vaccination of 26 rounds (range 6-89). Median vaccination and observation periods were 16 months (range 2-61) and 47 months (range 10-69), respectively. Three CH and all 6 LC patients had space-occupying lesions (SOLs) or a history of HCC, respectively. HCC became detectable during the vaccination period in 2 of the 3 CH patients with SOLs prior to vaccination. By contrast, HCC was undetectable throughout the vaccination period in the remaining 36 patients without SOLs. However, HCC became detectable in 4 of these 36 patients, i.e., 2 CH patients at 46 and 29 months after the end of the vaccination period, and 2 LC patients at 49 and :18 months after the end of vaccination. The development of HCC was associated with a reduction in boosted IgG responses to the vaccinated peptides. These results may provide new information on peptide vaccination for HCV-positive CH or LC patients lacking SOLs. Further studies are recommended to confirm the prophylactic,effects of peptide vaccination against HCC associated with HCV.