BACKGROUND/AIMS: A tumor vaccine consisting of formalin-fixed hepatocellular carcinoma (HCC) tissue fragments, biodegradable sustained-releasers of granulocyte-macrophage-colony stimulating factor (GM-CSF) and interleukin-2 (IL-2), and an adjuvant was developed. The aim of this study was to evaluate the effects of autologous tumor vaccine for protective immunity against HCC.METHODOLOGY: C57BL/6J mice were immunized intradermally with the Hepa1-6 tumor vaccine on day 0 and 7, followed by intrahepatic challenge with live Hepa1-6 cells. On day 21, the tumor volumes were measured and the effect of tumor vaccine was evaluated. Lymphocytes from the immunized mice were cultured and the specific cytotoxicity against Hepa1-6 was accessed. Then from March 1999 to June 2003, 67 patients with HCC undergoing curative resection were randomly divided into a tumor vaccine group (n = 32) and a control group (n = 35). Patients in the tumor vaccine group received 3 vaccinations at a 2-week interval and the control group only adjuvant treatment for symptoms. A delayed-type-hypersensitivity test was performed before and after vaccination. Primary endpoint was time to first recurrence and recurrent rates were analyzed.RESULTS: The tumor vaccine protected 87% of syngeneic mice from Hepa1-6 cells inoculation. In an in vitro experiment, splenocytes from the vaccinated mice exhibited a 56% lytic activity against the Hepa1-6 cells at an effector/target (E/T) ratio of 5, whereas they did not exhibit such activity against other tumor cells. The cytotoxic activity was inhibited by the treatment with anti-CD3, anti-CD8, and anti-MHC-class II monoclonal antibodies but not with anti-CD4 and anti-MHC-class I antibodies. In clinical trial, thirty-two patients had completed the tumor vaccine procedure and no essential adverse effect occurred. The follow-up averaged 33.6 months (range from 15 to 54 months). The recurrent rate was significantly better in the tumor vaccine group (1 year, 12.6%; 2 years, 35.9%; 3 years, 54%) than in the control group (1 year, 31.6%; 2 years, 61.3%; 3 years, 72.1%; P = 0.037). 23/32 patients developed a DTH response against the fragments of HCC and DTH-response-positive patients had a lower recurrent rate than DTH-response-negative patients (7/23 vs. 5/9).CONCLUSIONS: The autologous tumor vaccine is a promising adjunctive modality to prevent recurrence of human HCC.
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