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

Genetically engineered recombinant adenovirus expressing interleukin‑2 for hepatocellular carcinoma therapy

Regulatory and effector T cells possess immunological cytotoxicity for tumor cells in the tumor microenvironment during tumor progression and are the primary suppressors inhuman cancer therapy. Interleukin‑2 (IL‑2) is an anticancer cytokine, which triggers human innate and adaptive immunity by stimulating T cell propagation and lymphocyte infiltration into tumor sites. IL‑2 has been used successfully for cancer therapy. Recombinant adenovirus expressing IL‑2 (rAd‑IL‑2) injection is a gene therapy agent that may improve prognosis of hepatocellular carcinoma (HCC) patients. In the present study, the ability of IL‑2 to stimulate an immune response and the ability of recombinant adenovirus to inhibit tumor cell growth in HCC was investigated in a HCC tumor model. It was demonstrated that the regulatory and effector cell‑mediated tumor suppression by antitumor cluster of differentiation (CD)4+ and CD8+ T cells stimulated by rAd‑IL‑2 is tumor‑specific. Furthermore, rAd‑IL‑2 significantly stimulated tumor‑specific cytotoxic T lymphocyte responses, increased interferon‑γ release and enhanced antitumor immunity by inducing CD4+ and CD8+ T cell recruitment into the tumor, and additionally induced memory to protect tumor‑bearing mice against tumor challenge. Treatment with rAd‑IL‑2 led to tumor regression and long‑term survival of mice in the 120‑day treatment period. Tumor challenge experiments demonstrated that rAd‑IL‑2 induced memory, protecting against reinfection. In conclusion, rAd‑IL‑2 may promote tumor‑associated effector and regulatory T cell expansion and may be a potential therapeutic agent for clinical immunotherapy application in the treatment of cancer.

A multi-target protein of hTERTR-FAM96A presents significant anticancer potent in the treatment of hepatocellular carcinoma

The abilities to escape apoptosis induced by anticancer drugs are an essential factor of carcinogenesis and a hallmark of resistance to cancer therapy. In this study, we identified hTERTR-FAM96A (human telomerase reverse transcriptase–family with sequence similarity 96 member A) as a new efficient agent for apoptosome-activating and anti-tumor protein and investigated the potential tumor suppressor function in hepatocellular carcinoma. The hTERTR-FAM96A fusion protein was constructed by genetic engineering and its anticancer function of hTERTR-FAM96A was explored in vitro and in vivo by investigating the possible preclinical outcomes. Effects of hTERTR-FAM96A on improvement of apoptotic sensitivity and inhibition of migration and invasion were examined in cancer cells and tumors. Our results showed that the therapeutic effects of hTERTR-FAM96A were highly effective for inhibiting tumor growth and inducing apoptosis of hepatocellular carcinoma cells in H22-bearing nude mice. The hTERTR-FAM96A fusion protein could specifically bind with Apaf-1 and hTERT, which further induced apoptosis of hepatocellular carcinoma cells and improved apoptosis sensitivity. Our results indicated that hTERTR-FAM96A treatment enhanced cytotoxic effects by upregulation of cytotoxic T lymphocyte responses, interferon-γ release, and T lymphocyte infiltration. In addition, hTERTR-FAM96A led to tumor-specific immunologic cytotoxicity through increasing apoptotic body on hepatocellular tumors. Furthermore, hTERTR-FAM96A dramatically inhibited tumor growth, reduced death rate, and prolonged mice survival in hepatocellular carcinoma mice derived from three independent hepatocellular carcinoma mice cohorts compared to control groups. In summary, our data suggest that hTERTR-FAM96A may serve as an efficient anti-tumor agent for the treatment of hepatocellular carcinoma.

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.

Preclinical safety evaluation of rAd5-hTERTC27 by intravenous injection

The safety of rAd5-hTERTC27, a replication defective adenovirus vector carrying hTERTC27 for possible use against hepatocellular carcinoma (HCC) was assessed. In single-dose evaluations, intravenous dose levels of up to 2×10(11)VP/kg in rats and 9×10(10)VP/kg in monkeys were well tolerated with no abnormal changes in general signs, body weight and food consumption, and no significant differences in biochemical parameters, urinalysis, ECG, and systemic necropsy observations between the rAd5 groups and solvent control group except that slight hematological change was observed. No hemolytic effect using rabbit blood, local perivasculitis following intravenous injection in rabbits or systemic anaphylaxis in guinea pigs following intravenous dosing was seen. No effects on the central nervous system of mice occurred following intravenous dosing with the exception of an increase in sleep duration at the dose of 1.2×10(11)VP/kg (p<0.05) but not at lower doses of 2×10(10) and 6×10(10)VP/kg in the hypnotic synergism test. These results demonstrate that administration of rAd5-hTERTC27 was well tolerated in an initial set of safety studies as part of an evaluation to allow human trials for the treatment of HCC.