ME3738 enhances the effect of interferon and inhibits hepatitis C virus replication both in vitro and in vivo

Recent progress in the antiviral activity and mechanism study of pentacyclic triterpenoids and their derivatives

Viral infections cause many serious human diseases with high mortality rates. New drug‐resistant strains are continually emerging due to the high viral mutation rate, which makes it necessary to develop new antiviral agents. Compounds of plant origin are particularly interesting. The pentacyclic triterpenoids (PTs) are a diverse class of natural products from plants composed of three terpene units. They exhibit antitumor, anti‐inflammatory, and antiviral activities. Oleanolic, betulinic, and ursolic acids are representative PTs widely present in nature with a broad antiviral spectrum. This review focuses on the recent literatures in the antiviral efficacy of this class of phytochemicals and their derivatives. In addition, their modes of action are also summarized.

Antiproliferative effect of ME3738, a derivative of soyasapogenol, on hepatocellular carcinoma cell lines in vitro and in vivo

Soyasapogenol, an aglycon of soyasaponin, ameliorates liver injury induced by concanavalin A in mice. A derivative of soyasapogenol, 22β-methoxyolean-12-ene-3β, 24(4β)-diol (ME3738), was reported to induce the gene expression of interferon (IFN)-β in hepatitis C virus replicon cells. The effect of ME3738 on hepatocellular carcinoma (HCC) cell lines was investigated in the present study. A total of 11 HCC cell lines were cultured in medium containing 0-10 µM ME3738, and after 24, 48, or 72 h of culture, morphological observation and MTT cell growth assays were performed. Furthermore, the effects of ME3738 with or without PEG-IFN-α-2b on cell lines were investigated. Induction of apoptosis was examined on cells treated with 1 µM of ME3738 using an Annexin V assay. The effect of ME3738 (0.63 and 2.5 µM) on cell cycle progression was analyzed on two cell lines. The mice with subcutaneous tumors were divided into four groups: i) Control; ii) ME3738 alone; iii) PEG-IFN-α-2b alone and iv) ME3738+PEG-IFN-α-2b (combination). ME3738 was mixed with food (1.5 mg/g) and was taken orally for 15 days. PEG-IFN-α-2b (1,920 IU/mouse) was subcutaneously injected twice a week for two consecutive weeks. On day 15, the mice were sacrificed and the tumors were resected. A dose-dependent anti-proliferative effect was observed to various degrees in all the HCC cell lines in vitro. This inhibitory effect reached its maximal level 24 h after the treatment and the 50% inhibitory dose was between 0.8 and 2.4 µM. The combination treatment did not show a synergistic effect. Induction of apoptosis was not observed. Cell cycle arrest at S-phase was observed in two of the examined cell lines. On day 15, the tumor volume of mice receiving ME3738, PEG-IFN-α-2b, and ME3738+PEG-IFN-α-2b was 69, 30, and 33%, respectively, of the control tumor volume. ME3738 induced antiproliferative effects on the HCC cells in vitro and in vivo. The data suggested potential clinical application of ME3738.

Repurposing of the antihistamine chlorcyclizine and related compounds for treatment of hepatitis C virus infection

Hepatitis C virus (HCV) infection affects an estimated 185 million people worldwide, with chronic infection often leading to liver cirrhosis and hepatocellular carcinoma. Although HCV is curable, there is an unmet need for the development of effective and affordable treatment options. Through a cell-based high-throughput screen, we identified chlorcyclizine HCl (CCZ), an over-the-counter drug for allergy symptoms, as a potent inhibitor of HCV infection. CCZ inhibited HCV infection in human hepatoma cells and primary human hepatocytes. The mode of action of CCZ is mediated by inhibiting an early stage of HCV infection, probably targeting viral entry into host cells. The in vitro antiviral effect of CCZ was synergistic with other anti-HCV drugs, including ribavirin, interferon-α, telaprevir, boceprevir, sofosbuvir, daclatasvir, and cyclosporin A, without significant cytotoxicity, suggesting its potential in combination therapy of hepatitis C. In the mouse pharmacokinetic model, CCZ showed preferential liver distribution. In chimeric mice engrafted with primary human hepatocytes, CCZ significantly inhibited infection of HCV genotypes 1b and 2a, without evidence of emergence of drug resistance, during 4 and 6 weeks of treatment, respectively. With its established clinical safety profile as an allergy medication, affordability, and a simple chemical structure for optimization, CCZ represents a promising candidate for drug repurposing and further development as an effective and accessible agent for treatment of HCV infection.

Clinical efficacy of combination therapy with ME3738 and pegylated interferon-alpha-2a in patients with hepatitis C virus genotype 1

AIM

ME3738, a derivative of soyasapogenol B, enhances the anti-hepatitis C virus (HCV) effect of interferon in an in vitro replication system and an in vivo mouse model of HCV infection. ME3738 plus pegylated interferon (PEG IFN)-α-2a treatment for 12 weeks decreased HCV RNA levels in enrolled late virus responder (LVR) patients with relapsed HCV. Half of the patients reached undetectable HCV RNA level. The present clinical study of ME3738 was conducted in naïve chronic hepatitis C patients to investigate the sustained virological response (SVR) and safety of 48-week treatment with ME3738 plus PEG IFN-α-2a.

METHODS

Subjects (n = 135) with genotype 1b chronic hepatitis C with high viral loads were divided into three groups (ME3738 50 mg b.i.d., 200 mg b.i.d. or 800 mg b.i.d.). ME3738 was administrated p.o. and PEG IFN-α-2a (180 μg/week) s.c. for 48 weeks, and SVR was assessed at 24 weeks of treatment-free follow up.

RESULTS

The viral disappearance rates at 12 and 48 weeks were 23.0% and 48.9%, respectively. SVR was seen in 5.9% of subjects. ME3738 did not worsen the adverse reactions generally seen with PEG IFN-α-2a treatment, and any adverse reactions specific to ME3738 were not observed.

CONCLUSION

ME3738 plus PEG IFN-α-2a treatment to naïve chronic hepatitis C patients showed an antiviral effect and a good safety profile up to 48 weeks. However, HCV RNA was again detected in many subjects after treatment termination. Even though ME3738 is not enough to suppress HCV reproduction in this treatment. ME3738 was concurrently used with PEG IFN-α-2a treatment; however, a clear additional effect on SVR was not confirmed.

Long-term elimination of hepatitis C virus from human hepatocyte chimeric mice after interferon-γ gene transfer

Chronic hepatitis C virus (HCV) infection is a leading cause of cirrhosis, liver failure, and hepatocellular carcinoma. Although the combination therapy employing pegylated interferon (IFN)-α and ribavirin is effective, this treatment is effective in only approximately 50% patients with genotype 1 HCV infection. IFN-γ is a potent anti-HCV agent that exhibits its antiviral action through a receptor distinct from that for IFN-α. Therefore, IFN-γ application might provide an alternative approach to IFN-α-based therapies. However, recombinant IFN-γ protein exhibits a poor pharmacokinetic property, that is, a very short half-life. It is our hypothesis that sustained IFN-γ serum concentrations produced by gene transfer could effectively eliminate HCV in vivo. We examined the in vivo antiviral activity in human hepatocyte chimeric mice infected with genotype 1b HCV at high HCV RNA titers (10(5)-10(7) copies/ml). The human IFN-γ-expressing plasmid vector pCpG-huIFNγ exhibited prolonged transgene expression in mice compared with the plasmid vector pCMV-huIFNγ. Moreover, the gene transfer of pCpG-huIFNγ eliminated HCV from the liver of the chimeric mice for a sustained period. On the contrary, administration of pCMV-huIFNγ could not eliminate HCV. In conclusion, we found that a single pCpG-huIFNγ injection resulted in long-term elimination of HCV RNA in chimeric mice, providing, for the first time, direct evidence that chronic infection with high titer HCV in vivo can be treated by sustained IFN-γ treatment.

A translational study of resistance emergence using sequential direct-acting antiviral agents for hepatitis C using ultra-deep sequencing

OBJECTIVES

Direct-acting antiviral agents (DAAs) against hepatitis C virus (HCV) have recently been developed and are ultimately hoped to replace interferon-based therapy. However, DAA monotherapy results in rapid emergence of resistant strains and DAAs must be used in combinations that present a high genetic barrier to resistance, although viral kinetics of multidrug-resistant strains remain poorly characterized. The aim of this study is to track the emergence and fitness of resistance using combinations of telaprevir and NS5A or NS5B inhibitors with genotype 1b clones.

METHODS

HCV-infected chimeric mice were treated with DAAs, and resistance was monitored using direct and ultra-deep sequencing.

RESULTS

Combination therapy with telaprevir and BMS-788329 (NS5A inhibitor) reduced serum HCV RNA to undetectable levels. The presence of an NS3-V36A telaprevir resistance mutation resulted in poor response to telaprevir monotherapy but showed significant HCV reduction when telaprevir was combined with BMS-788329. However, a BMS-788329-resistant strain emerged at low frequency. Infection with a BMS-788329-resistant NS5A-L31V mutation rapidly resulted in gain of an additional NS5A-Y93A mutation that conferred telaprevir resistance during combination therapy. Infection with dual NS5AL31V/NS5AY93H mutations resulted in poor response to combination therapy and development of telaprevir resistance. Although HCV RNA became undetectable soon after the beginning of combination therapy with BMS-788329 and BMS-821095 (NS5B inhibitor), rebound with emergence of resistance against all three drugs occurred. Triple resistance also occurred following infection with the NS3V36A/NS5AL31V/NS5AY93H triple mutation.

CONCLUSIONS

Resistant strains easily develop from cloned virus strains. Sequential use of DAAs should be avoided to prevent emergence of multidrug-resistant strains.

Animal models for the study of hepatitis C virus infection and related liver disease

Hepatitis C virus (HCV) causes liver-related death in more than 300,000 people annually. Treatments for patients with chronic HCV are suboptimal, despite the introduction of directly acting antiviral agents. There is no vaccine that prevents HCV infection. Relevant animal models are important for HCV research and development of drugs and vaccines. Chimpanzees are the best model for studies of HCV infection and related innate and adaptive host immune responses. They can be used in immunogenicity and efficacy studies of HCV vaccines. The only small animal models of robust HCV infection are T- and B- cell deficient mice with human chimeric livers. Although these mice cannot be used in studies of adaptive immunity, they have provided new insights into HCV neutralization, interactions between virus and receptors, innate host responses, and therapeutic approaches. Recent progress in developing genetically humanized mice is exciting, but these models only permit studies of specific steps in the HCV life cycle and have limited or no viral replication.