Katsumi Terashita

New molecularly targeted therapies against advanced hepatocellular carcinoma: From molecular pathogenesis to clinical trials and future directions

Hepatocellular carcinoma (HCC) can be lethal due to its aggressive course and lack of effective systemic therapies for advanced disease. Sorafenib is the only systemic therapy that has demonstrated an overall survival benefit in patients with advanced HCC, and new agents for treatment of advanced HCC are needed. The multiple pathways involved in HCC oncogenesis, proliferation and survival provide many opportunities for the development of molecularly targeted therapies. Molecular targets of interest have expanded from angiogenesis to cancer cell‐directed oncogenic signaling pathways for treatment of advanced HCC. Agents targeting vascular endothelial growth factor receptor, epidermal growth factor receptor, fibroblast growth factor receptor, platelet‐derived growth factor receptor, c‐mesenchymal‐epithelial transition factor‐1 and mammalian target of rapamycin signaling have been actively explored. This article focuses on the evaluation of molecular agents targeting pathogenic HCC and provides a review of recently completed phase III drug studies (e.g. involving sorafenib, sunitinib, brivanib, linifanib, erlotinib, everolimus, ramucirumab or orantinib) and ongoing drug studies (e.g. involving lenvatinib, regorafenib, tivantinib or cabozantinib) of molecularly targeted agents in advanced HCC, including a brief description of the biologic rationale behind these agents.

Efficacy of therapy for advanced hepatocellular carcinoma: intra-arterial 5-fluorouracil and subcutaneous interferon with image-guided radiation.

Background and Aim:  To evaluate the efficacy of intra‐arterial 5‐fluorouracil (5‐FU) and subcutaneous interferon (IFN) combined with image‐guided radiation therapy (IGRT) in advanced hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT).

Prevalence and characteristics of naturally occurring sofosbuvir resistance-associated variants in patients with hepatitis C virus genotype 1b infection.

Sofosbuvir (SOF), a nucleotide analog pro‐drug, targets hepatitis C virus (HCV) NS5B polymerase and shows potential for treating HCV infection, given its high efficacy and good barrier to resistance. However, in addition to the rare resistant‐associated variant (RAV) of non‐structural protein NS5B S282T, several new potential RAVs of SOF have been reported, especially related to HCV genotype 1b. However, the prevalence and characteristics of these RAVs have not been clarified.

EGFR inhibitors prevent induction of cancer stem-like cells in esophageal squamous cell carcinoma by suppressing epithelial-mesenchymal transition

There exists a highly tumorigenic subset of esophageal squamous cell carcinoma (ESCC) cells defined by high expression of CD44. A novel therapy targeting these cancer stem-like cells (CSCs) is needed to improve prognosis of ESCC. CSCs of ESCC have a mesenchymal phenotype and epithelial-mesenchymal transition (EMT) is critical to enrich and maintain CSCs. EGFR, frequently overexpressed in ESCC, has pivotal roles in EMT induced by TGF-β in invasive fronts. Thus, EMT in invasive fronts of ESCC might be important for CSCs and EGFR could be a target of a novel therapy eliminating CSCs. However, effects of EGFR inhibitors on CSCs in ESCC have not been fully examined. EGFR inhibitors, erlotinib and cetuximab, significantly suppressed enrichment of CSCs via TGF-β1-mediated EMT. Importantly, EGFR inhibitors sharply suppressed ZEB1 that is essential for EMT in ESCC. Further, EGFR inhibitors activated Notch1 and Notch3, leading to squamous cell differentiation. EGFR inhibition may suppress expression of ZEB1 and induce differentiation, thereby blocking EMT-mediated enrichment of CSCs. In organotypic 3D culture, a form of human tissue engineering, tumor cells in invasive nests showed high expression of CD44. Erlotinib significantly blocked invasion into the matrix and CD44 high expressing CSCs were markedly suppressed by erlotinib in organotypic 3D culture. In conclusion, EMT is a critical process for generation of CSCs and the invasive front of ESCC, where EMT occurs, might form a CSC niche in ESCC. EGFR inhibitors could suppress EMT in invasive fronts and be one therapeutic option targeting against generation of CSCs in ESCC.

Safety and efficacy of daclatasvir and asunaprevir in hepatitis C virus‐infected patients with renal impairment

Hepatitis C virus (HCV) infection is a risk factor for end‐stage renal disease, renal graft failure, and hemodialysis patient mortality. However, the efficacy of direct‐acting antiviral therapy for HCV‐infected patients with renal impairment is unclear. Additionally, the promising NS5B inhibitor sofosbuvir has not been recommended for patients with severe renal impairment. In this prospective, multicenter study, we evaluated the efficacy and safety of daclatasvir and asunaprevir combination therapy, with a focus on patients with renal impairment.

A pivotal role of Krüppel-like factor 5 in regulation of cancer stem-like cells in hepatocellular carcinoma

In hepatocellular carcinoma (HCC), there exists a highly tumorigenic subset of cells defined by high expression of CD44 and CD133 that has been reported to contain cancer stem-like cells (CSCs). Krüppel-like factor 5 (KLF5) regulates many factors involved in cell cycle, migration, inflammation, angiogenesis and stemness and has cancer-promoting effects in some cancers. While some reports have indicated that KLF5 may have important roles in regulation of CSCs, what role, if any, KLF5 plays in regulation of CSCs in HCC remains to be elucidated. Flow cytometric analysis of CD44 and CD133 in HCC cell lines revealed subpopulations of CD44High/CD133High and CD44Low/CD133Low cells. We subsequently sorted these subpopulations and identified KLF5 as a gene that is significantly upregulated in CD44High/CD44High cells via RNA sequencing using next generation sequencing technology. Moreover, KLF5 overexpression enriched the CD44High/CD133High subpopulation and, consistent with the up-regulation of CD44High/CD133High cells, KLF5 overexpressing cells were more resistant to anti-cancer drugs and displayed enhanced colony-formation capacity. By contrast, knock-down of KLF5 by siRNA diminished the CD44High/CD133High subpopulation. When KLF5 was acetylated by TGF-β1, the KLF5-mediated CD44High/CD133High subpopulation enrichment was abrogated. Oppositely, ectopic expression of an acetylation-deficient KLF5 mutant further increased CD44High/CD133High subpopulations as compared to cell expressing wild-type KLF5. These findings provide novel mechanistic insight into a pivotal role for KLF5 in the regulation of CSCs in HCC.

ZEB1 expression is associated with prognosis of intrahepatic cholangiocarcinoma

Background/Aim Intrahepatic cholangiocarcinoma (ICC) is one of the most aggressive malignant tumours, so the identification of molecular targets for ICC is an important issue. Zinc finger E-box binding homeobox 1 (ZEB1) is a key inducer of epithelial–mesenchymal transition (EMT). The aim of the present study was to clarify the clinical significance of ZEB1 in ICC and the associations between ZEB1 expression and EMT-related proteins. Methods We immunohistochemically examined the expression of EMT-related proteins, namely ZEB1, vimentin and E-cadherin, in ICC specimens from 102 patients. The clinicopathological and prognostic values of these markers were evaluated. Results ZEB1 and vimentin were expressed in 46.1% and 43.1% of tumours, respectively, and E-cadherin expression was lost in 44.1% of tumours. ZEB1 expression showed a significant inverse correlation with E-cadherin expression (p=0.004) and a positive correlation with vimentin expression (p=0.022). Altered expression of ZEB1 was associated with aggressive tumour characteristics, including advanced tumour stage (p=0.037), undifferentiated-type histology (p=0.017), lymph node metastasis (p=0.024) and portal vein invasion (p=0.037). Moreover, overall survival rates were significantly lower for patients with high ZEB1 expression than for patients with low ZEB1 expression (p=0.027). Kaplan–Meier analysis also identified E-cadherin expression (p=0.041) and vimentin expression (p=0.049) as prognostic indicators for overall survival. Conclusions ZEB1 expression is associated with tumour progression and poor prognosis in patients with ICC through positive correlations with vimentin and negative correlations with E-cadherin. ZEB1 expression is associated with a poor prognosis and might be an attractive target for the treatment of ICC.

Safety and efficacy of sofosbuvir and ribavirin for genotype 2 hepatitis C Japanese patients with renal dysfunction: SOF/RBV for patients with renal dysfunction

The safety and efficacy of sofosbuvir (SOF) and ribavirin (RBV) have not been well clarified in patients with renal dysfunction because clinical trials have not included such patients. We evaluated the safety and efficacy of SOF and RBV for genotype 2 hepatitis C virus (HCV)‐infected patients with renal dysfunction.

Anti-adipogenic and antiviral effects of l-carnitine on hepatitis C virus infection.

Hepatitis C virus (HCV) has been reported to hijack fatty acid metabolism in infected hepatocytes, taking advantage of lipid droplets for virus assembly. In this study, we analyzed the anti‐HCV activity of l‐carnitine, a substance involved in the transport of fatty acids into mitochondria. JFH‐1 or HCV replicon‐transfected Huh7.5.1 cells were treated with or without l‐carnitine to examine its anti‐HCV effects. The effects of l‐carnitine on HCV entry, HCV‐induced adipogenesis and lipid droplet formation, and HCV‐induced oxidative stress were examined. Treatment of JFH‐1‐infected cells with l‐carnitine inhibited HCV propagation in a concentration‐dependent manner. In contrast, l‐carnitine had no anti‐HCV activity in the HCV replicon system, which is lacking viral assembly. In addition, l‐carnitine did not affect HCV entry. However, l‐carnitine treatment decreased intracellular lipid droplets, which are crucial for HCV assembly in JFH‐1‐infected cells. The expression level of CPT‐1 was decreased in JFH‐1‐infected cells, and l‐carnitine treatment restored this expression. HCV‐infected cells exhibited increased production of reactive oxygen species and glutathione oxidation. l‐carnitine decreased oxidative stress induced by JFH‐1‐infection, as shown by glutathione/glutathione disulfide assays and MitoSOX staining. l‐carnitine exhibited anti‐HCV activity, possibly by inhibiting HCV assembly and through its anti‐adipogenic activity in HCV‐infected cells. Moreover, l‐carnitine has antioxidant properties in HCV‐infected hepatocytes. Overall, these results indicated that l‐carnitine may be an effective adjunctive agent in antiviral therapies to treat chronic hepatitis C. J. Med. Virol. 89:857–866, 2017.

Add-on effects of fluvastatin in simeprevir/pegylated-interferon/ribavirin combination therapy for patients with genotype 1 hepatitis C virus infection: A randomized controlled study: FLV add-on SMV/Peg-IFN/RBV therapy

The Japan Society of Hepatology guidelines indicate that hepatitis C virus (HCV) protease inhibitor combination therapy with simeprevir (SMV), pegylated‐interferon (Peg‐IFN), and ribavirin (RBV) is a therapeutic option for patients who fail to respond to a direct direct‐acting antiviral‐containing regimen. However, treatment outcomes have room for improvement. Fluvastatin (FLV) add‐on treatment in Peg‐IFN and RBV combination therapy for HCV‐infected patients significantly improved the sustained virologic response (SVR), but the add‐on effect of FLV on SMV combination therapy is not well understood.