Long-term toxicity study of rAd5-hTERTC27 in SD rats and Cynomolgus monkeys by intravenous injection.

rAd5-hTERTC27, a replication-defective adenovirus vector carrying hTERTC27, has been proposed for possible use against hepatocellular carcinoma (HCC). In this study, we investigated the long-term toxicity of rAd5-hTERTC27 in SD rats and Cynomolgus monkeys. rAd5-hTERTC27 was administered intravenously once a week for 13 weeks followed by a one-month recovery period. As of 4 months, all animals displayed overall good health. Anti-adenoviral antibodies emerged in a dose-independent manner. The levels of complement components, C3 and C4, in the rAd5-hTERTC27 middle-dose and high-dose groups and C4 in the rAd5-EGFP group increased significantly after the 2nd treatment in monkeys. Slight-mild pathological changes of the liver occurred only in the rAd5-hTERTC27 high-dose group (2/16) in rats and not in any other group in either rats or monkeys. With the increase of the dose, the incidence of lymphocyte depletion in the spleen of rats and reactive hyperplasia of the splenic corpuscle in monkeys increased. However, the changes in the liver and spleen were reversible. Given the above data, intravenous administration of rAd5-hTERTC27 (up to 4×10(10)VP/kg in rats and 0.9×10(10)VP/kg in monkeys) appears to be well-tolerated, providing support for its potentially safe use in clinical trials for the treatment of HCC.

Inhibition of hepatocellular carcinoma growth by adenovirus-mediated expression of human telomerase reverse transcriptase COOH-27 terminal polypeptide in mice.

A 27-kDa C-terminal fragment of human telomerase reverse transcriptase, hTERTC27, has previously been reported to inhibit the growth and tumorigenicity of HeLa human cervical cancer cells and U87-MG human glioblastoma multiforme cells. However, the antitumor effects of hTERTC27 in hepatoma and its underlying mechanisms are unclear. In the current study, the therapeutic effect of hTERTC27, mediated by recombinant adenovirus, in hepatocellular carcinoma (HCC) was explored in vitro and in vivo to investigate the possible mechanisms. The results indicated that recombinant adenovirus carrying hTERTC27 (rAdv-hTERTC27) effectively inhibited the growth and induced apoptosis of the Hepa 1-6 HCC cells. Dendritic cells transduced with rAdv-hTERTC27 were highly effective at inducing antigen-specific T cell proliferation and increasing the activated cytotoxicity of T cells against Hepa 1-6 cells. HCC was inhibited significantly when a single dose of 5×107 pfu rAdv-hTERTC27 was administered intravenously. In summary, the results of this study demonstrated that rAdv-hTERTC27 may serve as a reagent for intravenous administration when combined with telomerase-based gene therapy and immunotherapy for cancer.

Effective antitumor immunity against murine gliomas using dendritic cells transduced with hTERTC27 recombinant adenovirus.

hTERTC27, a 27-kDa hTERT C-terminal polypeptide has been demonstrated to cause hTERT-positive HeLa cell apoptosis and inhibits the growth of mouse melanoma. hTERTC27 has been associated with telomere dysfunction, regulation of gene-regulated apoptosis, the cell cycle and activation of natural killer (NK) cells, but its mechanism of action is not fully understood. Here, we report that dendritic cells (DCs) transduced with hTERTC27 can increase T-cell proliferation, and augment the concentration of interleukin-2 (IL-2) and interferon-γ (IFN-γ) in the supernatants of T cells. It can also induce antigen-specific cytotoxic T lymphocytes (CTL) against glioma cells in vitro. Moreover, hTERTC27 gene-transduced DCs exhibit a very potent cytotoxicity to glioma cells in vivo. It could prolong the survival time and inhibit the growth of glioma-bearing mice. These data suggest that hTERTC27 gene-transduced DCs can efficiently enhance immunity against gliomas in vitro and in vivo.