Development of systemic therapy for hepatocellular carcinoma at 2013: Updates and insights

Targeting EGFR/PI3K/AKT/mTOR Signaling in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) poses a significant global health concern, with its incidence steadily increasing. The development of HCC is a multifaceted, multi-step process involving alterations in various signaling cascades. In recent years, significant progress has been made in understanding the molecular signaling pathways that play central roles in hepatocarcinogenesis. In particular, the EGFR/PI3K/AKT/mTOR signaling pathway in HCC has garnered renewed attention from both basic and clinical researchers. Preclinical studies in vitro and in vivo have shown the effectiveness of targeting the key components of this signaling pathway in human HCC cells. Thus, targeting these signaling pathways with small molecule inhibitors holds promise as a potential therapeutic option for patients with HCC. In this review, we explore recent advancements in understanding the role of the EGFR/PI3K/AKT/mTOR signaling pathway in HCC and assess the effectiveness of targeting this signaling cascade as a potential strategy for HCC therapy based on preclinical studies.

Effects of matrine in combination with cisplatin on liver cancer

Matrine, an alkaloid isolated from Sophora flavescens, promotes tumor cell apoptosis and strengthens the anticancer capacity of chemotherapeutic drugs. The present study aimed to investigate the inhibitory effect and underlying mechanism of matrine in combination with cisplatin on liver cancer progression. Tumor progression was studied in nude mice. The human liver cancer cell line HepG2 was injected into BALB/c nude mice subcutaneously to establish a tumor model. Mice were subsequently treated with matrine, cisplatin, matrine + cisplatin or normal saline. Nude mice and tumor growth were monitored. Tumors were excised and the expression of survivin, caspase-3, caspase-7 and caspase-9 was detected by immunohistochemistry. Western blotting was used to determine the expression of survivin, caspase-3, caspase-7, caspase-9 and X-linked inhibitor of apoptosis protein (XIAP) in tumor tissues. The results demonstrated that matrine exerted anticancer effects in liver cancer-transplanted tumors, as evidenced by decrease in tumor weight and volume. Furthermore, the tumor inhibition rate in mice treated with matrine + cisplatin was 83.3%, whereas it was of 37.5 and 75% in mice treated with matrine or cisplatin alone, respectively. In addition, the expression of survivin and XIAP was significantly downregulated, whereas the expression of caspase-3, caspase-7 and caspase-9 was significantly upregulated in tumor tissues from nude mice treated with matrine + cisplatin, compared with those treated with cisplatin, matrine or normal saline. These findings suggested that the combination of matrine and cisplatin may promote tumor cell apoptosis in liver cancer by activating the caspase apoptosis pathway and suppressing the survivin-associated inhibition of caspase-9.

Nucleostemin Modulates Outcomes of Hepatocellular Carcinoma via a Tumor Adaptive Mechanism to Genomic Stress

Hepatocellular carcinomas (HCC) are adapted to survive extreme genomic stress conditions imposed by hyperactive DNA replication and genotoxic drug treatment. The underlying mechanisms remain unclear, but may involve intensified DNA damage response/repair programs. Here, we investigate a new role of nucleostemin (NS) in allowing HCC to survive its own malignancy, as NS was previously shown to promote liver regeneration via a damage repair mechanism. We first established that a higher NS transcript level correlates with high-HCC grades and poor prognostic signatures, and is an independent predictor of shorter overall and progression-free survival specifically for HCC and kidney cancer but not for others. Immunostaining confirmed that NS is most abundantly expressed in high-grade and metastatic HCCs. Genome-wide analyses revealed that NS is coenriched with MYC target and homologous recombination (HR) repair genes in human HCC samples and functionally intersects with those involved in replication stress response and HR repair in yeasts. In support, NS-high HCCs are more reliant on the replicative/oxidative stress response pathways, whereas NS-low HCCs depend more on the mTOR pathway. Perturbation studies showed NS function in protecting human HCC cells from replication- and drug-induced DNA damage. Notably, NS depletion in HCC cells increases the amounts of physical DNA damage and cytosolic double-stranded DNA, leading to a reactive increase of cytokines and PD-L1. This study shows that NS provides an essential mechanism for HCC to adapt to high genomic stress for oncogenic maintenance and propagation. NS deficiency sensitizes HCC cells to chemotherapy but also triggers tumor immune responses. IMPLICATIONS: HCC employs a novel, nucleostemin (NS)-mediated-mediated adaptive mechanism to survive high genomic stress conditions, a deficiency of which sensitizes HCC cells to chemotherapy but also triggers tumor immune responses.

Proliferation of human hepatocellular carcinoma cells from surgically resected specimens under conditionally reprogrammed culture

Hepatocellular carcinoma (HCC) is the third most common cause of cancer mortality worldwide, which is partially due to the lack of appropriate therapeutic options. The development of HCC is accompanied with unique and continuous genomic and epigenetic modifications. Therefore, the absence of a personalized and reproducible human model reduces the ability to determine the potential of candidate treatments. Conditional reprogramming (CR) culture has been used to establish and indefinitely grow patient‑derived tumor cell lines in a rapid and efficient manner. In the present study, primary HCC cells were isolated from tumor specimens and cultured under CR conditions. The proliferative potential and capacity of cells to undergo continuous regeneration were evaluated by cell viability and proliferation assays, and the expression of tumor‑specific markers was determined by western blotting and immunofluorescence to determine the prospects for use in clinical settings. It was demonstrated that ~55% of tumor samples were able to generate HCC cells that could be continuously expanded and passaged under CR conditions; this ability was associated with the source and composition of the tumor tissues. Furthermore, the expression of the tumor‑specific marker α‑fetoprotein and the proliferative ability of cells were maintained following cycles of cryopreservation and resuscitation. In conclusion, with further optimization, the CR system may be a useful tool for the precise therapeutic treatment of patients with HCC.

SAC3D1: a novel prognostic marker in hepatocellular carcinoma

Centrosome-associated proteins are recognized as prognostic factors in many cancers because centrosomes are critical structures for the cell cycle progression and genomic stability. SAC3D1, however, is associated with centrosome abnormality, although its prognostic potential has not been evaluated in hepatocellular carcinoma (HCC). In this study, 3 independent cohorts (GSE10186, n = 80; TCGA, n = 330 and ICGC, n = 237) were used to assess SAC3D1 as a biomarker, which demonstrated SAC3D1 overexpression in HCC tissues when compared to the matched normal tissues. Kaplan-Meier survival analysis also showed that its overexpression was associated with poor prognosis of HCC with good discriminative ability in 3 independent cohorts (GSE10186, P = 0.00469; TCGA, P = 0.0000413 and ICGC, P = 0.0000114). Analysis of the C-indices and AUC values further supported its discriminative ability. Finally, multivariate analysis confirmed its prognostic significance (GSE10186, P = 0.00695; TCGA, P = 0.0000289 and ICGC, P = 0.0000651). These results suggest a potential of SAC3D1 as a biomarker for HCC.

3-bromopyruvate and buthionine sulfoximine effectively kill anoikis-resistant hepatocellular carcinoma cells

BACKGROUND & AIMS

Acquisition of anoikis resistance is a prerequisite for metastasis in hepatocellular carcinoma (HCC). However, little is known about how energy metabolism and antioxidant systems are altered in anoikis-resistant (AR) HCC cells. We evaluated anti-tumor effects of a combination treatment of 3-bromopyruvate (3-BP) and buthionine sulfoximine (BSO) in AR HCC cells.

METHODS

We compared glycolysis, reactive oxygen species (ROS) production, and chemoresistance among Huh-BAT, HepG2 HCC cells, and the corresponding AR cells. Expression of hexokinase II, gamma-glutamylcysteine synthetase (rGCS), and epithelial-mesenchymal transition (EMT) markers in AR cells was assessed. Anti-tumor effects of a combination treatment of 3-BP and BSO were evaluated in AR cells and an HCC xenograft mouse model.

RESULTS

AR HCC cells showed significantly higher chemoresistance, glycolysis and lower ROS production than attached cells. Expression of hexokinase II, rGCS, and EMT markers was higher in AR HCC cells than attached cells. A combination treatment of 3-BP/BSO effectively suppressed proliferation of AR HCC cells through apoptosis by blocking glycolysis and enhancing ROS levels. In xenograft mouse models, tumor growth derived from AR HCC cells was significantly suppressed in the group treated with 3-BP/BSO compared to the group treated with 3-BP or sorafenib.

CONCLUSIONS

These results demonstrated that a combination treatment of 3-BP/BSO had a synergistic anti-tumor effect in an AR HCC model. This strategy may be an effective adjuvant therapy for patients with sorafenib-resistant HCC.

Randomized, open-label phase 2 study comparing frontline dovitinib versus sorafenib in patients with advanced hepatocellular carcinoma

Angiogenesis inhibition by the vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR) inhibitor sorafenib provides survival benefit in hepatocellular carcinoma (HCC); however, angiogenic escape from sorafenib may occur due to angiogenesis-associated fibroblast growth factor receptor (FGFR) pathway activation. In addition to VEGFR and PDGFR, dovitinib inhibits FGFR. Frontline oral dovitinib (500 mg/day, 5 days on, 2 days off; n = 82) versus sorafenib (400 mg twice daily; n = 83) was evaluated in an open-label, randomized phase 2 study of Asian-Pacific patients with advanced HCC. The primary and key secondary endpoints were overall survival (OS) and time to tumor progression (TTP) as determined by a local investigator, respectively. Patients included in the study were ineligible for surgical and/or locoregional therapies or had disease progression after receiving these therapies. The median OS (95% confidence interval [CI]) was 8.0 (6.6-9.1) months for dovitinib and 8.4 (5.4-11.3) months for sorafenib. The median TTP (95% CI) per investigator assessment was 4.1 (2.8-4.2) months and 4.1 (2.8-4.3) months for dovitinib and sorafenib, respectively. Common any-cause adverse events included diarrhea (62%), decreased appetite (43%), nausea (41%), vomiting (41%), fatigue (35%), rash (34%), and pyrexia (30%) for dovitinib and palmar-plantar erythrodysesthesia syndrome (66%) and decreased appetite (31%) for sorafenib. Subgroup analysis revealed a significantly higher median OS for patients in the dovitinib arm who had baseline plasma soluble VEGFR1 (sVEGFR1) and hepatocyte growth factor (HGF) below median levels versus at or above the median levels (median OS [95% CI]: sVEGFR1, 11.2 [9.0-13.8] and 5.7 [4.3-7.0] months, respectively [P = .0002]; HGF, 11.2 [8.9-13.8] and 5.9 [5.0-7.6] months, respectively [P = 0.0002]).

CONCLUSION

Dovitinib was well tolerated, but activity was not greater than sorafenib as a frontline systemic therapy for HCC. Based on these data, no subsequent phase 3 study has been planned. (Hepatology 2016;64:774-784).

AGK enhances angiogenesis and inhibits apoptosis via activation of the NF-κB signaling pathway in hepatocellular carcinoma

High levels of angiogenesis and resistance to apoptosis are major clinical features of hepatocellular carcinoma (HCC), a lethal disease with a high incidence worldwide. However, the precise mechanisms underlying these malignant properties remain unclear. Here, we demonstrated that acylglycerol kinase (AGK) is markedly overexpressed in HCC cell lines and clinical tissues. Immunohistochemical analysis of 245 clinical HCC specimens revealed patients with high levels of AGK expression had poorer overall survival compared to patients with low AGK expression. Furthermore, overexpressing AGK significantly enhanced angiogenesis and inhibited apoptosis in vitro and promoted the tumorigenicity of HCC cells in vivo; silencing endogenous AGK had the opposite effects. Importantly, AGK enhanced angiogenesis and inhibited apoptosis in HCC in part via activation of NF-κB signaling. Our findings provide new evidence that AGK plays an important role in promoting angiogenesis and providing resistance to apoptosis, thus AGK may represent a novel therapeutic target for HCC.

Novel therapeutic targets and predictive markers for hepatocellular carcinoma

INTRODUCTION

Following the approval of sorafenib as the first systemic agent for treatment of advanced hepatocellular carcinoma (HCC), there have been an increasing number of targeted treatments under testing for the cancer. However, most of the recently published drug trials in HCC failed to produce remarkable results. The researchers are actively pursuing novel therapeutic targets as well as predictive biomarker for treatment of HCC.

AREAS COVERED

This review discusses a number of potential novel targets for drug development of HCC. Focus is put on the underlying rationale for therapeutic development of the target and the possibility of using a predictive biomarker to select patients for drug testing.

EXPERT OPINION

Future direction of drug development will be discussed. Notably, a clinical trial on drug testing in HCC should be shifted from all-comers approach to selected populations based on underlying viral etiology and molecular targets. A study to evaluate predictive biomarker is crucial to the development of targeted agents for HCC. Design of clinical trials on HCC should introduce measures to encourage acquisition of tumor and plasma samples for biomarker development.

Current management of hepatocellular carcinoma: an Eastern perspective

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death, especially in Eastern areas. With advancements in diagnosis and treatment modalities for HCC, the survival and prognosis of HCC patients are improving. However, treatment patterns are not uniform between areas despite efforts to promote a common protocol. Although many hepatologists in Asian countries may adopt the principles of the Barcelona Clinic Liver Cancer staging system, they are also independently making an effort to expand the indications of each treatment and to combine therapies for better outcomes. Several expanded criteria for liver transplantation in HCC have been developed in Asian countries. Living donor liver transplantation is much more commonly performed in these countries than deceased donor liver transplantation, and it may be preceded by other treatments such as the down-staging of tumors. Local ablation therapies are often combined with transarterial chemoembolization (TACE) and the outcome is comparable to that of surgical resection. The indications of TACE are expanding, and there are new types of transarterial therapies. Although data on drug-eluting beads, TACE, and radioembolization in Asian countries are still relatively sparse compared with Western countries, these methods are gradually gaining popularity because of better tolerability and the possibility of improved response rates. Hepatic arterial infusion chemotherapy and radiotherapy are not included in Western guidelines, but are currently being used actively in several Asian countries. For more advanced HCCs, appropriate combinations of TACE, radiotherapy, and sorafenib can be considered, and emerging data indicate improved outcomes of combination therapies compared with single therapies. To include these paradigm shifts into newer treatment guidelines, more studies may be needed, but they are certainly in progress.