Research Progresses of Targeted Therapy and Immunotherapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, with nearly one million new cases and deaths every year. Owing to the complex pathogenesis, hidden early symptoms, rapidly developing processes, and poor prognosis, the morbidity and mortality of HCC are increasing yearly. With the progress being made in modern medicine, the treatment of HCC is no longer limited to traditional methods. Targeted therapy and immunotherapy have emerged to treat advanced and metastatic HCC in recent years. Since Sorafenib is the first molecular targeting drug against angiogenesis, targeted drugs for HCC are continually emerging. Moreover, immunotherapy plays a vital role in clinical trials. In particular, the application of immune checkpoint inhibitors, which have received increasing attention in the field of cancer treatment, is a possible research path. Interestingly, these two therapies generally complement each other at some stages of HCC, bringing new hope for patients with advanced HCC. In this paper, we discuss the research progress of targeted therapy and immunotherapy for HCC in recent years, which will provide a reference for the further development of drugs for HCC.

Recent developments of c-Met as a therapeutic target in hepatocellular carcinoma

Aberrant c-Met activity has been implicated in the development of hepatocellular carcinoma (HCC), suggesting that c-Met inhibition may have therapeutic potential. However, clinical trials of nonselective kinase inhibitors with c-Met activity (tivantinib, cabozantinib, foretinib, and golvatinib) in patients with HCC have failed so far to demonstrate significant efficacy. This lack of observed efficacy is likely due to several factors, including trial design, lack of patient selection according to tumor c-Met status, and the prevalent off-target activity of these agents, which may indicate that c-Met inhibition is incomplete. In contrast, selective c-Met inhibitors (tepotinib, capmatinib) can be dosed at a level predicted to achieve complete inhibition of tumor c-Met activity. Moreover, results from early trials can be used to optimize the design of clinical trials of these agents. Preliminary results suggest that selective c-Met inhibitors have antitumor activity in HCC, with acceptable safety and tolerability in patients with Child-Pugh A liver function. Ongoing trials have been designed to assess the efficacy and safety of selective c-Met inhibition compared with standard therapy in patients with HCC that were selected based on tumor c-Met status. Thus, c-Met inhibition continues to be an active area of research in HCC, with well-designed trials in progress to investigate the benefit of selective c-Met inhibitors. (Hepatology 2018;67:1132-1149).

Dual inhibition of Akt and c-Met as a second-line therapy following acquired resistance to sorafenib in hepatocellular carcinoma cells

Sorafenib displays a limited efficacy for advanced hepatocellular carcinoma (HCC). Some patients with HCC initially respond to sorafenib, but eventually succumb to the disease, indicating that the acquired resistance to sorafenib reduces its beneficial effects. No alternative drugs are available after the failure of sorafenib therapy. Therefore, investigation of the mechanisms underlying the acquired resistance and development of second-line treatments for sorafenib-resistant HCC are urgently required. In this study, sorafenib-resistant HCC cells generated from sorafenib-sensitive human HCC cells were shown to overproduce hepatocyte growth factor (HGF) and overexpress c-Met kinase and its phosphorylated form, leading to the activation of Akt and ERK (extracellular signaling-regulated kinase) pathways. Use of specific c-Met inhibitors enhanced the effects of sorafenib by inhibiting the growth of sorafenib-resistant HCC cells. Akt inhibitors, a class of second-line therapeutic drugs under investigation for treating HCC in clinical trials, enhanced the effects of sorafenib, but also activated the c-Met pathway in sorafenib-resistant cells. Dual inhibition of Akt and c-Met by their respective inhibitors, MK2206 and capmatinib, additively or synergistically suppressed sorafenib-resistant HCC cells in vitro and sorafenib-resistant HCC xenografts in mice. The anticancer activities of MK2206 mainly rely on its ability to induce cell apoptosis and autophagic death, while capmatinib treatment leads to cell cycle arrest at phase G1. These results provide strong evidence for further investigation on the clinical utility of dual inhibition of Akt and c-Met, particularly MK2206 and capmatinib, as a second-line therapy for advanced HCC that has acquired resistance to sorafenib.

Clinical Development of c-MET Inhibition in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death. In patients with advanced or unresectable HCC, there are few treatment options. Conventional chemotherapy has limited benefits. Sorafenib, a multi-kinase inhibitor, improves survival, but options for patients intolerant of or progressing on sorafenib are limited. There has been much interest in recent years in molecular therapeutic targets and drug development for HCC. One of the more promising molecular targets in HCC is the cellular-mesenchymal-epithelial transition (c-MET) factor receptor. Encouraging phase II data on two c-MET inhibitors, tivantinib and cabozantinib, has led to phase III trials. This review describes the c-MET/hepatocyte growth factor (HGF) signalling pathway and its relevance to HCC, and discusses the preclinical and clinical trial data for inhibitors of this pathway in HCC.

Population pharmacokinetics modeling and analysis of foretinib in adult patients with advanced solid tumors

Foretinib is a multikinase inhibitor that inhibits multiple receptor tyrosine kinases, including MET and VEGFR, with the potential for treatment of solid tumors. Hepatocellular carcinoma (HCC) pathogenesis is associated with overexpression of MET, and physiologic changes in the livers of HCC patients may decrease CYP3A isozyme-mediated metabolism of foretinib. A population pharmacokinetic model of foretinib was developed to explore the effect of tumor type, formulation, and other covariates. Data from 1 HCC study in Asia and 3 non-HCC studies in the United States with varying foretinib regimens and formulations were used for analysis. A 2-compartment model with a linear first-order absorption and elimination and lag time in absorption adequately described foretinib pharmacokinetics in 132 advanced non-HCC and HCC patients and identified an effect of formulations on bioavailability. The bisphosphate salt capsules and freebase tablets had a relative bioavailability 37% and 20% higher, respectively, than the solution formulation. HCC patients had ≈19.6% lower mean clearance (70.14 L/h), ≈16% lower mean volume of distribution (1725.6 L), and higher dose-normalized exposure compared with non-HCC patients. This could be a result of differences in metabolism in HCC patients, body weight, or activity of CYP3A isozymes between Asian and Western cancer patients.

Systemic treatment of advanced hepatocellular carcinoma: from disillusions to new horizons

Hepatocellular carcinoma (HCC) is an aggressive malignancy, which accounts for a third of all cancer deaths globally each year. The management of patients with HCC is complex, as both the tumour stage and any underlying liver disease must be considered conjointly. Since the approval of sorafenib in advanced HCC, several phase III clinical trials have failed to demonstrate any superiority over sorafenib in the frontline setting, and no agent has been shown to impact outcomes after sorafenib failure. This review will focus on the range of experimental therapeutics for patients with advanced HCC and highlight the successes and failures of these treatments as well as areas for future development. Specifics such as dose limiting toxicity and safety profile in patients with liver dysfunction related to the underlying chronic liver disease should be considered when developing therapies in HCC. Finally, robust validated and reproducible surrogate end-points as well as predictive biomarkers should be defined in future randomised trials.

Dissecting signaling pathways in hepatocellular carcinoma: new perspectives in medical therapy

Prognosis of patients with advanced hepatocellular carcinoma (HCC) is poor and is largely influenced by associated liver comorbidities. Moreover, effective treatment alternatives are limited; with the exception of the multitargeted inhibitor sorafenib, established options in the treatment of advanced HCC no longer amenable with ablative or locoregional procedures are lacking. In light of the limited efficacy of chemotherapy in this setting, great efforts have been made in the definition of targetable molecular pathways with a central role in the progression of HCC. Targeting angiogenesis, growth factor receptors, intracellular transduction pathways, or mechanisms of gene-expression regulation represents the main way to improve patient outcome. At the same time, identifying clinical and biological factors, which may help selecting patients with higher chances of benefit, is essential in order to hasten drug development and maximize treatment efficacy.

Met as a therapeutic target in HCC: facts and hopes

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide, and its burden is expected to increase further in the next years. In spite of the advances of classical therapies, such as surgery, transplantation, use of radiofrequency and transarterial embolization, the prognosis of this neoplasm has not considerably improved over the past few years. The advent of targeted therapies and the approval of the systemic treatment of advanced HCC with the kinase inhibitor sorafenib have provided some hope for the future. Even if the molecular mechanisms responsible for the onset and progression of HCC are still largely unknown, new therapeutic targets have recently come to the spotlight. One of these targets is the tyrosine kinase receptor for the Hepatocyte Growth Factor, encoded by the MET gene, known to promote tumor growth and metastasis in many human organs. In this review we will summarize the contrasting results obtained in vitro (in HCC cell lines) and in animal experimental models and we will also try to analyze the reasons for the opposite findings, suggesting that the HGF/MET axis can have either a promoting or a suppressive role in the development of HCC. We will also reconsider the evidence of activation of this pathway in human HCCs and discuss the results of the clinical trials performed with MET inhibitors. The final purpose is to better clarify which can be the role of MET as a therapeutic target in HCC.

The Met receptor tyrosine kinase: a key player in oncogenesis and drug resistance

The Met receptor tyrosine kinase (RTK) is an attractive oncology therapeutic target. Met and its ligand, HGF, play a central role in signaling pathways that are exploited during the oncogenic process, including regulation of cell proliferation, invasion, angiogenesis, and cancer stem cell regulation. Elevated Met and HGF as well as numerous Met genetic alterations have been reported in human cancers and correlate with poor outcome. Alterations of pathways that regulate Met, such as the ubiquitin ligase c-Cbl are also likely to activate Met in the oncogenic setting. Moreover, interactive crosstalk between Met and other receptors such as EGFR, HER2 and VEGFR, underlies a key role for Met in resistance to other RTK-targeted therapies. A large body of preclinical and clinical data exists that supports the use of either antibodies or small molecule inhibitors that target Met or HGF as oncology therapeutics. The prognostic potential of Met expression has been suggested from studies in numerous cancers including lung, renal, liver, head and neck, stomach, and breast. Clinical trials using Met inhibitors indicate that the level of Met expression is a determinant of trial outcome, a finding that is actively under investigation in multiple clinical scenarios. Research in Met prognostics and predictors of drug response is now shifting toward more sophisticated methodologies suitable for development as validated and effective biomarkers that can be partnered with therapeutics to improve patient survival.

Targeting the HGF/c-MET pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a significant cause of cancer-related morbidity and mortality worldwide. Despite improvements in local therapies, including surgical resection, liver transplantation, and transarterial embolization, the prognosis remains poor for the majority of patients who develop recurrence or present with advanced disease. Systemic therapy with the tyrosine kinase inhibitor sorafenib represents a milestone in advanced HCC but provides a limited survival benefit. Ongoing efforts to study hepatocarcinogenesis have identified an important role for c-MET signaling in the promotion of tumor growth, angiogenesis, and metastasis. In this review, we summarize the preclinical data from human tissue, cell lines, and animal models that implicate c-MET in the pathogenesis of HCC. We also evaluate potential biomarkers that may estimate prognosis or predict response to c-MET inhibitors for more rational clinical trial design. Finally, we discuss the latest clinical trials of c-MET inhibitors in advanced HCC.