Mechanisms of resistance to sorafenib and the corresponding strategies in hepatocellular carcinoma

Sorafenib, the unique drug as first-line treatment for advanced hepatocellular carcinoma (HCC), has opened a window of hope after searching for effective agents to combat HCC for decades. However, the overall outcomes are far from satisfactory. One of the explanations is the genetic heterogeneity of HCC, which has led to identifying predictive biomarkers for primary resistance to sorafenib, and then applying the concept of personalized medicine, or seeking therapeutic strategies such as combining sorafenib with other anticancer agents. Some of the combinations have demonstrated a better effectiveness than sorafenib alone, with good tolerance. The acquired resistance to sorafenib has also drawn attention. As a multikinase inhibitor, sorafenib targets several cellular signaling pathways but simultaneously or sequentially the addiction switches and compensatory pathways are activated. Several mechanisms are involved in the acquired resistance to sorafenib, such as crosstalks involving PI3K/Akt and JAK-STAT pathways, hypoxia-inducible pathways, epithelial-mesenchymal transition, etc . Based on the investigated mechanisms,some other molecular targeted drugs have been applied as second-line treatment for treat HCC after the failure of sorafenib therapy and more are under evaluation in clinical trials. However, the exact mechanisms accounting for sorafenib resistance remains unclear. Further investigation on the crosstalk and relationship of associated pathways will better our understanding of the mechanisms and help to find effective strategies for overcoming sorafenib resistance in HCC.     

Targeted and immune therapies for hepatocellular carcinoma:Predictions for 2019 and beyond

Systemic therapy for hepatocellular carcinoma(HCC) has markedly advanced since the survival benefit of a molecular targeted agent, sorafenib, were demonstrated in the SHARP and Asia Pacific trials in 2007. Treatment options for patients with advanced HCC increased by sorafenib, and long-term survival for patients with advanced stage HCC has become possible to some extent. However,development of a more potent first-line novel molecular targeted agent replacing sorafenib and a potent second-line agent after disease progression on or intolerant to sorafenib has been warranted because sorafenib lacks tumor shrinking/necrotizing effects and induces relatively severe adverse events such as hand foot skin reaction. Many agents in the 1 st line and 2 nd line setting were attempted to develop between 2007 and 2016, but all of these clinical trials failed.On the other hand, clinical trials of 4 agents(regorafenib, lenvatinib,cabozantinib, and ramucirumab) succeeded in succession in 2017 and 2018, and their use in clinical practice is possible(regorafenib and lenvatinib) or underway(cabozantinib and ramucirumab). Furthermore, all of 5 clinical trials of combination therapy with transcatheter chemoembolization(TACE) plus a molecular targeted agent failed to date, however, the combination of TACE and sorafenib(TACTICS trials) was reported to be successful and presented at ASCO in 2018. Phase 3 clinical trials of immune checkpoint inhibitors and a combination therapy of immune checkpoint inhibitors and molecular targeted agents are also ongoing, which suggests treatment paradigm of HCC in all stages from early,intermediate and advanced stage, is expected to be changed drastically in the very near future.     

Molecularly targeted therapies for hepatocellular carcinoma: sorafenib as a stepping stone

Since sorafenib, a multikinase inhibitor targeting angiogenesis of hepatocellular carcinoma (HCC), demonstrated survival benefits in recent clinical trials, it has changed the treatment paradigm and become the standard first-line treatment for patients with advanced HCC. However, disease stabilization with sorafenib lasts a few months, possibly due to the development of resistance, and thus the survival advantage was modest, even in patients with preserved liver function. Furthermore, there is currently no biomarker for monitoring the response or resistance to sorafenib. Currently, various kinds of molecularly targeted agents have been developed and are being evaluated in clinical trials. There are several steps required to improve the outcome from sorafenib therapy. First, a reliable predictive and prognostic biomarker is urgently needed. Second, a compelling indication of sorafenib treatment for HCC needs more clinical studies and consensus. Third, the actual benefits of sorafenib to patients with advanced liver dysfunction should be clarified and a more effective strategy for targeted therapy needs to be developed, for example, using a combination of targeted agents acting on different pathways or different levels of a key pathway. Finally, sorafenib could be used with other treatment modalities, such as local ablation or transarterial chemoembolization, to synergize efficacy. Based on the successful introduction of sorafenib, future studies should focus on plans to further improve the outcome of HCC patients by overcoming resistance and maximizing the efficacy of molecularly targeted therapy.     

Recent advances in multidisciplinary management of hepatocellular carcinoma

The incidence of hepatocellular carcinoma(HCC) is increasing, and it is currently the second leading cause of cancer-related death worldwide. Potentially curative treatment options for HCC include resection, transplantation, and percutaneous ablation, whereas palliative treatments include trans-arterial chemoembolization(TACE), radioembolization, and systemic treatments. Due to the diversity of available treatment options and patients’ presentations, a multidisciplinaryteam should decide clinical management of HCC, according to tumor characteristics and stage of liver disease. Potentially curative treatments are suitable for very-early- and early-stage HCC. However, the vast majority of HCC patients are diagnosed in later stages, where the tumor characteristics or progress of liver disease prevent curative interventions. For patients with intermediate-stage HCC, TACE and radioembolization improve survival and are being evaluated in addition to potentially curative therapies or with systemic targeted therapy. There is currently no effective systemic chemotherapy, immunologic, or hormonal therapy for HCC, and sorafenib is the only approved moleculartargeted treatment for advanced HCC. Other targeted agents are under investigation; trials comparing new agents in combination with sorafenib are ongoing. Combinations of systemic targeted therapies with local treatments are being evaluated for further improvements in HCC patient outcomes. This article provides an updated and comprehensive overview of the current standards and trends in the treatment of HCC.     

Targeted therapy of hepatocellular carcinoma: present and future

Following the encouraging results of sorafenib in advanced hepatocellular carcinoma (HCC), targeted therapy has become a new direction of research in the treatment of HCC. Emerging data provide evidence that the pathogenesis and progression of HCC are mediated by a number of molecular defects and dysregulated pathways. Novel targeted therapies are designed to inhibit the aberrant pathways at a molecular level with an aim to improve the clinical outcome. For the past few years, an increasing number of targeted agents have been tested in HCC in the clinical setting. This review aims to summarize the current status of clinical development of targeted therapy in HCC, with focus on novel agents targeting angiogenesis, signal transduction and epigenetic dysregulation of tumors. The review also discusses the lessons learned from outcomes of completed clinical trials and provides perspectives on future clinical trials in HCC.     

Targeted systemic therapies for hepatocellular carcinoma: clinical perspectives, challenges and implications

Hepatocellular carcinoma(HCC) is a lethal disease in most patients,due to its aggressive course and a lack of effective systemic therapies for advanced disease.Surgical resection and liver transplantation remain the only curative options for a small subset of patients.Few patients with HCC are diagnosed early enough to be eligible for curative treatment.Angiogenesis inhibition is a natural therapeutic target for all solid tumors,but particularly for the highly vascularized HCC tumors.With the approval of the targeted agent sorafenib,there are now additional options for patients with HCC.Although sorafenib does produce some improvement in survival in HCC patients,the responses are not durable.In addition,there are significant dermatologic,gastrointestinal,and metabolic toxicities,and,as importantly,there is still limited knowledge of its usefulness in special subpopulations with HCC.Other angiogenesis inhibitors are in development to treat HCC both in the first-line setting and for use following sorafenib failure;the furthest in development is brivanib,a dual fibroblast growth factor pathway and vascular endothelial growth factor receptor inhibitor.Additional agents with antiangiogenic properties also in phase Ⅱ and Ⅲ development for the treatment of patients with HCC include bevacizumab,ramucirumab,ABT-869,everolimus and ARQ 197.     

Molecular targeted therapy for hepatocellular carcinoma:Current and future

Hepatocellular carcinoma(HCC)is one of the most frequent tumors worldwide.The majority of HCC cases occur in patients with chronic liver disease.Despite regular surveillance to detect small HCC in these patients,HCC is often diagnosed at an advanced stage.Because HCC is highly resistant to conventional systemic therapies,the prognosis for advanced HCC patients remains poor.The introduction of sorafenib as the standard systemic therapy has unveiled a new direction for future research regarding HCC treatment.However,given the limited efficacy of the drug,a need exists to look beyond sorafenib.Many molecular targeted agents that inhibit different pathways involved in hepatocarcinogenesis are under various phases of clinical development,and novel targets are being assessed in HCC.This review aims to summarize the efforts to target molecular components of the signaling pathways that are responsible for the development and progression of HCC and to discuss perspectives on the future direction of research.     

Role of anti-angiogenesis therapy in the management of hepatocellular carcinoma: The jury is still out

As the leading cause of disease-related deaths, cancer is a major public health threat worldwide. Surgical resection is still the first-line therapy for patients with early-stage cancers. However, postoperative relapse and metastasis remain the cause of 90% of deaths of patients with solid organ malignancies, including hepatocellular carcinoma (HCC). With the rapid development of molecular biology techniques in recent years, molecularly targeted therapies using monoclonal antibodies, small molecules, and vaccines have become a milestone in cancer therapeutic by significantly improving the survival of cancer patients, and have opened a window of hope for patients with advanced cancer. Hypervascularization is a major characteristic of HCC. It has been reported that anti-angiogenic treatments, which inhibit blood vessel formation, are highly effective for treating HCC. However, the efficacy and safety of anti-angiogenesis therapies remain controversial. Sorafenib is an oral multikinase inhibitor with anti-proliferative and anti-angiogenic effects and is the first molecular target drug approved for the treatment of advanced HCC. While sorafenib has shown promising therapeutic effects, substantial evidence of primary and acquired resistance to sorafenib has been reported. Numerous clinical trials have been conducted to evaluate a large number of molecularly targeted drugs for treating HCC, but most drugs exhibited less efficacy and/or higher toxicity compared to sorafenib. Therefore, understanding the mechanism(s) underlying sorafenib resistance of cancer cells is highlighted for efficiently treating HCC. This concise review aims to provide an overview of anti-angiogenesis therapy in the management of HCC and to discuss the common mechanisms of resistance to anti-angiogenesis therapies.     

Current status and future prospects of chemotherapy for advanced hepatocellular carcinoma

Sorafenib is the only drug that demonstrates a survival benefit for advanced hepatocellular carcinoma (HCC). However, the therapeutic effect of sorafenib is limited, so development of a more effective treatment method and second-line treatments is needed. Since the advent of sorafenib, clinical studies have been conducted with a variety of drugs and treatment methods, mainly with molecular targeted therapy, but almost all trials have ended in failure. The reasons for the difficulty in the development of a novel drug or treatment method include the diversity of mechanisms in the carcinogenesis and development of HCC, as well as the presence of background liver diseases such as chronic hepatitis and cirrhosis. Trials with immune-checkpoint inhibitors, which have an entirely different anti-tumor mechanism from that of molecular targeted drugs or cytotoxic drugs, have recently begun. Based on the results to date, clinical trials are now being conducted with enriched target subjects. In the future, providing more individualized treatment approaches for patients with advanced HCC will be essential.     

根治性肝切除联合索拉非尼治疗肝细胞癌的研究进展

根治性肝切除仍然是肝细胞癌(hepatocellularcarcinoma,HCC)的主要治疗手段,但术后转移复发导致肝切除的疗效进入瓶颈期.探索术后复发的治疗措施是有效延长患者生存时间的重要课题.目前,以经皮肝动脉化疗栓塞为代表的多种治疗措施已在临床广泛开展,但尚缺乏大规模、多中心随机对照临床试验的循证医学证据.分子靶向药物索拉非尼的出现为改善HCC预后开辟了新局面,对于已接受过根治性肝切除治疗的HCC患者,索拉非尼可能是一种有效的辅助治疗方法,值得深入探索.     

Management of advanced hepatocellular carcinoma in the era of targeted therapy

Systemic chemotherapy has had a disappointing track record in the management of advanced hepatocellular carcinoma (HCC). Single‐agent doxorubicin produces a response rate of 10–15%, but without any survival benefit, and combination chemotherapy has also yielded unimpressive results. With recent advances in the knowledge of hepato‐carcinogenesis, there has been encouraging development in the systemic therapy of advanced HCC patients, and particularly in the targeted therapy of advanced HCC. Among the newly identified targets, exciting results have been shown in targeting the anti‐angiogenic pathway and the Raf/mitogen‐activated protein kinase pathways. Bevacizumab, both as a single agent and in combination with other agents, has shown initial encouraging activity in treating advanced HCC. More recently, single‐agent sorafenib, a putative multitargeted kinase inhibitor, has shown to prolong the overall survival of patients with advanced HCC in the pivotal phase III Sorafenib HCC Assessment Randomized Protocol (SHARP) and Oriental study. Currently, sorafenib is the only approved targeted therapy for patients with advanced HCC. In addition, however, promising early results have been reported for other molecular‐targeted drugs including erlotinib and sunitinib. Future progress seems likely to depend on using controlled clinical trials to optimize synergistic combination treatments.     

Optimal combination of antiangiogenic therapy for hepatocellular carcinoma

The success of sorafenib in prolonging survival of patients with hepatocellular carcinoma (HCC) makes therapeutic inhibition of angiogenesis a component of treatment for HCC. To enhance therapeutic efficacy, overcome drug resistance and reduce toxicity, combination of antiangiogenic agents with chemotherapy, radiotherapy or other targeted agents were evaluated. Nevertheless, the use of antiangiogenic therapy remains suboptimal regarding dosage, schedule and duration of therapy. The issue is further complicated by combination antiangiogenesis to other cytotoxic or biologic agents. There is no way to determine which patients are most likely respond to a given form of antiangiogenic therapy. Activation of alternative pathways associated with disease progression in patients undergoing antiangiogenic therapy has also been recognized. There is increasing importance in identifying, validating and standardizing potential response biomarkers for antiangiogenesis therapy for HCC patients. In this review, biomarkers for antiangiogenesis therapy including systemic, circulating, tissue and imaging ones are summarized. The strength and deficit of circulating and imaging biomarkers were further demonstrated by a series of studies in HCC patients receiving radiotherapy with or without thalidomide.     

Hepatocellular carcinoma review:Current treatment,and evidence-based medicine

Hepatocellular carcinoma(HCC)is the fifth most common tumor worldwide.Multiple treatment options are available for HCC including curative resection,liver transplantation,radiofrequency ablation,trans-arterial chemoembolization,radioembolization and systemic targeted agent like sorafenib.The treatment of HCC depends on the tumor stage,patient performance status and liver function reserve and requires a multidisciplinary approach.In the past few years with significant advances in surgical treatments and locoregional therapies,the short-term survival of HCC has improved but the recurrent disease remains a big problem.The pathogenesis of HCC is a multistep and complex process,wherein angiogenesis plays an important role.For patients with advanced disease,sorafenib is the only approved therapy,but novel systemic molecular targeted agents and their combinations are emerging.This article provides an overview of treatment of early and advanced stage HCC based on our extensive review of relevant literature.     

非编码RNA在索拉非尼治疗肝细胞癌耐药中的作用机制

索拉非尼作为晚期肝细胞癌的一线治疗药物,能够有效改善肝癌患者预后。但索拉非尼耐药已经成为影响肝细胞癌治疗效果的主要障碍。近年来研究发现,非编码RNA在肝细胞癌索拉非尼耐药中起着关键作用。总结了非编码RNA通过诱导肝癌细胞自噬、促进肝癌干细胞增殖、促进肝癌细胞上皮-间质转化过程、抑制肝癌细胞凋亡以及调节肝癌组织微环境来调节肝癌细胞对索拉非尼的敏感性。指出了非编码RNA调控肝细胞癌索拉非尼耐药的分子机制在克服耐药方面的潜在临床意义。     

Future treatment option for hepatocellular carcinoma: a focus on brivanib

Hepatocellular carcinoma (HCC), one of the most common cancers worldwide, is particularly prevalent in the Asia-Pacific region. Guidelines on the treatment of HCC in Japan come from both consensus-based and evidence-based treatment algorithms. However, patients with extensive liver damage and/or more advanced disease (major vascular invasion and/or extrahepatic spread) are currently ineligible for any treatment. Recent knowledge of hepatocarcinogenesis has led to the targeting of new pathways, particularly the angiogenic pathway, with a specific focus on the vascular endothelial growth factor receptor (VEGFR). Apparently the most studied systemic antiangiogenic agent for HCC is sorafenib. An updated version of the aforementioned treatment algorithms recommends sorafenib therapy for advanced HCC patients with Child-Pugh A liver function and extrahepatic spread or major vascular invasion. Moreover, sorafenib is recommended for use in HCC patients who are refractory or intolerant to transarterial chemoembolization (TACE) with well-preserved liver function (Child-Pugh A). However, one of the unresolved issues is anti-VEGF resistance. It is speculated that novel antiangiogenic agents that combine inhibition of other pathways such as fibroblast growth factor receptor signaling in addition to VEGFR signaling might provide a potential mechanism to overcome anti-VEGF resistance in HCC. Brivanib inhibits both VEGF and fibroblast growth factor receptor signaling. To further investigate the benefits of brivanib for advanced HCC, a broad-spectrum, global, phase III development plan, the Brivanib studies in HCC patients at RISK (BRISK) clinical program, has been initiated. Clinical benefits seen with brivanib in the first-line setting, and following the failure of sorafenib therapy, highlight the potential to improve the clinical course of patients with advanced HCC, and this agent may provide a novel therapeutic option for the growing population of patients for whom no other treatment choice exists.     

Hepatic artery infusion chemotherapy for advanced hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is one of the most common cancers worldwide. Surgery, percutaneous ablation and liver transplantation are the only curative treatment modalities for HCC. However, the majority of patients have unresectable disease at diagnosis. Therefore, effective treatment options for patients with advanced HCC are required. In advanced HCC, according to current international guidelines, sorafenib, a molecular targeted agent, is the standard treatment. However, alternative treatment modalities are required because of the low response rates and unsuitability of molecular agents in real practice. In various treatment modalities, mostly in Asia, hepatic arterial infusion chemotherapy(HAIC) has been applied to advanced HCC with a view to increasing the therapeutic efficacy. HAIC provides direct drug delivery into the tumor feeding vessels and also minimizes systemic toxicities through a greater first-pass effect in the liver. However, the sample sizes of studies on HAIC have been small and large randomized trials are still lacking. In this article, we describe the treatment efficacy of HAIC for advanced stage HCC and discuss future therapeutic possibilities.     

Signaling pathway and molecular-targeted therapy for hepatocellular carcinoma

In recent years, molecular-targeted agents have been used clinically to treat various malignant tumors. In May 2009, sorafenib (Nexavar?) was approved in Japan for 'unresectable hepatocellular carcinoma (HCC)', and was the first molecular-targeted agent for use in HCC. To date, sorafenib is the only molecular-targeted agent whose survival benefit has been demonstrated in two global phase III randomized controlled trials, and has now been approved worldwide. Phase III clinical trials of other molecular-targeted agents comparing them with sorafenib as first-line treatment agents are now ongoing. Those agents target the vascular endothelial growth factor, platelet-derived growth factor receptors, as well as target the epidermal growth factor receptor, insulin-like growth factor receptor and mammalian target of rapamycin, in addition to other molecules targeting other components of the signal transduction pathways. This review outlines the main pathways involved in the development and progression of HCC and the agents that target these pathways. Finally, current status and future perspective will also be discussed.     

Current chemotherapies for advanced hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) increases with the advancement of chronic liver diseases such as hepatitis C or B. The recurrence rate is very high and causes disease progression to an advanced stage. Recent development of molecularly targeted agents for the treatment of advanced HCC has dramatically changed the chemotherapies used for this disease. We summarize the current findings on several drugs that are commonly used for the treatment of advanced HCC including sorafenib and hepatic arterial infusion chemotherapies.     

Treatment for hepatocellular carcinoma in Japan over the last three decades: Our experience and published work review

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer‐related mortality worldwide. In the last few decades, there has been a marked increase in therapeutic options for HCC and epidemiological characteristics at HCC diagnosis have also significantly changed. With these changes and advances in medical technology and surveillance program for detecting earlier stage HCC, survival in patients with HCC has significantly improved. Especially, patients with liver cirrhosis are at high risk of HCC development, and regular surveillance could enable early detection of HCC and curative therapy, with potentially improved clinical outcome. However, unfortunately, only 20% of HCC patients are amenable to curative therapy (liver transplantation, surgical resection or ablative therapies). Locoregional therapies such as radiofrequency ablation, percutaneous ethanol injection, microwave coagulation therapy and transcatheter arterial chemoembolization play a key role in the management of unresectable HCC. Currently, molecular‐targeted agents such as sorafenib have emerged as a promising therapy for advanced HCC. The choice of the treatment modality depends on the size of the tumor, tumor location, anatomical considerations, number of tumors present and liver function. Furthermore, new promising therapies such as gene therapy and immunotherapy for HCC have emerged. Approaches to the HCC diagnosis and adequate management for patients with HCC are improving survival. Herein, we review changes of epidemiological characteristics, prognosis and therapies for HCC and refer to current knowledge for this malignancy based on our experience of approximately 4000 HCC cases over the last three decades.     

Management of hepatocellular carcinoma with transarterial chemoembolization in the era of systemic targeted therapy

The clinical management of hepatocellular carcinoma (HCC) is often complicated by poor liver function. Treatment options for intermediate- and advanced-stage disease are limited. Transcatheter arterial chemoembolization (TACE) is an effective first-line therapy for intermediate-stage HCC. By interrupting blood flow to the tumor and administering concentrated chemotherapy locoregionally, TACE induces necrosis at the tumor site, but may create conditions that permit or encourage angiogenesis and recurrence of the tumor. Combination of TACE with new targeted agents may be an effective way to treat intermediate-stage HCC, particularly in higher risk patients. Because of the efficacy and safety of sorafenib-the first systemic therapy to show significant clinical benefit in advanced HCC-there is great interest in its potential use in combination with existing treatment modalities. The synergistic combination of TACE plus sorafenib represents a promising opportunity for tumor control.