Prospects for immunotherapy as a novel therapeutic strategy against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly aggressive malignant disease, with a poor clinical prognosis. Many standard therapies are often considered for HCC treatment today; however, these conventional therapies often fail to achieve sufficiently effective clinical results. Today, HCC therapy is set to undergo a major revolution, owing to rapid developments in cancer immunotherapy, particularly immune checkpoint inhibitor therapy. Cancer immunotherapy is a novel and promising treatment strategy that differs significantly from conventional therapies in its approach to achieve antitumor effects. In fact, many cancer immunotherapies have been tested worldwide and shown to be effective against various types of cancer; HCC is no exception to this trend. For example, we identified a specific cancer antigen called glypican-3 (GPC3) and performed clinical trials of GPC3-targeted peptide vaccine immunotherapy in patients with HCC. Here, we present an overview of the immune mechanisms for development and progression of HCC, our GPC3-based immunotherapy, and immune checkpoint inhibitor therapy against HCC. Finally, we discuss the future prospects of cancer immunotherapy against HCC. We believe that this review and discussion of cancer immunotherapy against HCC could stimulate more interest in this promising strategy for cancer therapy and help in its further development.

Systemic treatment of advanced hepatocellular cancer: new hope on the horizon

INTRODUCTION

Hepatocellular carcinoma (HCC) is among the leading causes of cancer-related mortality in the world. The majority of the patients present at an advanced or incurable stage where neither locoregional treatment nor combination treatment of locoregional treatment and systemic therapies is feasible. For decades sorafenib was the only treatment option available for advanced HCC. However, with the advent of new and more effective therapies recently, the overall prognosis of advanced HCC has improved significantly. Areas covered: This review summarises the current systemic treatment options available and future prospects in the management of advanced HCC where patients are not suitable for locoregional treatment. Expert opinion: New effective targeted therapeutics have dramatically changed the treatment landscape for advanced HCC. The incorporation of sequential therapy including sorafenib or lenvatinib as first-line treatment and immunotherapy, regorafenib or cabozantinib as second-line treatment have significantly improved outcomes for patients with advanced HCC. Further development of novel combinations of these new agents and predictive/prognostic biomarkers are being explored. Efforts should also be made to tailor treatment to individual patients based on etiology, clinical and molecular factors.

Immune checkpoint blockade and its combination therapy with small-molecule inhibitors for cancer treatment

Initially understood for its physiological maintenance of self-tolerance, the immune checkpoint molecule has recently been recognized as a promising anti-cancer target. There has been considerable interest in the biology and the action mechanism of the immune checkpoint therapy, and their incorporation with other therapeutic regimens. Recently the small-molecule inhibitor (SMI) has been identified as an attractive combination partner for immune checkpoint inhibitors (ICIs) and is becoming a novel direction for the field of combination drug design. In this review, we provide a systematic discussion of the biology and function of major immune checkpoint molecules, and their interactions with corresponding targeting agents. With both preclinical studies and clinical trials, we especially highlight the ICI + SMI combination, with its recent advances as well as its application challenges.

Evolving Systemic Therapy in Hepatocellular Carcinoma: Current Management and Opportunities for Integration With Radiotherapy

The majority of patients with hepatocellular carcinoma (HCC) present with advanced disease. While first-line therapy with sorafenib is considered standard of care for patients with advancedHCC, outcomes remain poor. Despite early evidence of antitumor activity from Phase II trials of multiple other tyrosine kinase inhibitors, Phase III trials have largely failed to show an improvement insurvival outcomes over sorafenib. Given the encouraging early results with liver-directed radiotherapy for patients with advanced HCC, there is an increased interest in combination of these therapies tooptimize patient outcomes and improve survival by maximizing both local and distant disease control. Phase II trials of checkpoint inhibitors in HCC have also reported encouraging results, and Phase IIItrials are ongoing. Trials of combining radiotherapy with immunotherapy in solid tumors have shown intriguing results, potentially reflecting the opportunity for synergistic effects with the use of both modalities.

Immunotherapy for hepatocellular carcinoma: current status and future perspectives

The discovery of the immune checkpoint mechanism has contributed greatly to recent advances in cancer treatment. The anticytotoxic T lymphocyte-associated protein 4 antibody ipilimumab was first approved as a therapeutic drug for malignant melanoma in the USA in 2011; since then, antiprogrammed cell death 1 (PD-1) antibody and antiprogrammed death-ligand 1 (PD-L1) antibody have also been approved and clinically introduced and are indicated for the treatment of various cancers. Numerous clinical studies are now underway to evaluate the efficacy of immune checkpoint inhibitors for patients with many kinds of cancer, including hepatocellular carcinoma (HCC), and the outcomes of these trials are highly anticipated. Synergic effects of immune checkpoint inhibitors used in combination with molecular targeted agents or local therapy have also been suggested, resulting in expectations regarding the use of these drugs in combination with existing standard treatment methods for HCC. Thus, the treatment of HCC is now entering an age of significant innovation triggered by the clinical introduction of immune checkpoint inhibitors.

Programmed cell death protein-1 (PD-1)/programmed death-ligand-1 (PD-L1) axis in hepatocellular carcinoma: prognostic and therapeutic perspectives

Hepatocellular carcinoma (HCC) is the most common primary neoplasia of the liver. There have been tremendous efforts in the development of therapeutic strategies in the last decades. As opposed to other cancer entities immunotherapy has just recently gained popularity in HCC. Among various immunotherapy approaches, programmed cell death protein-1 (PD-1), and its ligand programmed death receptor ligand-1 (PD-L1) axis became one of the most promising pathway of the decade. The scientific interest in PD-1/PD-L1 axis is definitely justified due to: ability to detect PD-L1 expression in patients that underwent resection for HCC with prognostic values; the role of serum PD-L1 as a tool to identify early recurrences and to monitor treatment outcome; PD-1/PDL1 is a highly targetable pathway, with possible predictive markers, and with high clinical applicability that might help us in selecting a subgroup of HCC patients who are most likely to benefit from PD-1/PD-L1 inhibitors. In this review we will first discuss the prognostic role of PD-1/PD-L1 as a bio-marker in various clinical scenarios. Afterwards we will critically analyse the recently published trials with PD-1/PD-L1 inhibitors in HCC either alone or in combination with other treatment modalities. The higher focus will be on clinical rather than preclinical studies. Nevertheless, the strengths and limits of PD-1/PD-L1 axis in both prognosis and therapy of HCC will be highlighted.

Systemic Therapy for Hepatocellular Carcinoma: Latest Advances

Systemic therapy for hepatocellular carcinoma (HCC) has changed drastically since the introduction of the molecular targeted agent sorafenib in 2007. Although sorafenib expanded the treatment options for extrahepatic spread (EHS) and vascular invasion, making long-term survival of patients with advanced disease achievable to a certain extent, new molecular-targeted agents are being developed as alternatives to sorafenib due to shortcomings such as its low response rate and high toxicity. Every single one of the many drugs developed during the 10-year period from 2007 to 2016 was a failure. However, during the two-year period from 2017 through 2018, four drugs—regorafenib, lenvatinib, cabozantinib, and ramucirumab—emerged successfully from clinical trials in quick succession and became available for clinical use. The efficacy of combination therapy with transcatheter arterial chemoembolization (TACE) plus sorafenib was also first demonstrated in 2018. Recently, immune checkpoint inhibitors have been applied to HCC treatment and many phase III clinical trials are ongoing, not only on monotherapy with nivolumab, pembrolizumab, and tislelizumab, but also on combination therapy with checkpoint inhibitors, programmed death-1 (PD-1) or PD-ligand 1 (PD-L1) antibody plus a molecular targeted agent (bevacizumab) or the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) antibody, tremelimumab. These combination therapies have shown higher response rates than PD-1/PD-L1 monotherapy alone, suggesting a synergistic effect by combination therapy in early phases; therefore, further results are eagerly awaited.

Molecular therapies and precision medicine for hepatocellular carcinoma

The global burden of hepatocellular carcinoma (HCC) is increasing and might soon surpass an annual incidence of 1 million cases. Genomic studies have established the landscape of molecular alterations in HCC; however, the most common mutations are not actionable, and only ~25% of tumours harbour potentially targetable drivers. Despite the fact that surveillance programmes lead to early diagnosis in 40-50% of patients, at a point when potentially curative treatments are applicable, almost half of all patients with HCC ultimately receive systemic therapies. Sorafenib was the first systemic therapy approved for patients with advanced-stage HCC, after a landmark study revealed an improvement in median overall survival from 8 to 11 months. New drugs - lenvatinib in the frontline and regorafenib, cabozantinib, and ramucirumab in the second line - have also been demonstrated to improve clinical outcomes, although the median overall survival remains ~1 year; thus, therapeutic breakthroughs are still needed. Immune-checkpoint inhibitors are now being incorporated into the HCC treatment armamentarium and combinations of molecularly targeted therapies with immunotherapies are emerging as tools to boost the immune response. Research on biomarkers of a response or primary resistance to immunotherapies is also advancing. Herein, we summarize the molecular targets and therapies for the management of HCC and discuss the advancements expected in the near future, including biomarker-driven treatments and immunotherapies.

The Role of Angiogenesis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for about 90% of all primary liver cancers and is the second leading cause of cancer-related deaths worldwide. The hypervascular nature of most HCC tumors underlines the importance of angiogenesis in the pathobiology of these tumors. Several angiogenic pathways have been identified as being dysregulated in HCC, suggesting they may be involved in the development and pathogenesis of HCC. These data provide practical targets for systemic treatments such as those targeting the vascular endothelial growth factor receptor and its ligand. However, the clinical relevance of other more recently identified angiogenic pathways in HCC pathogenesis or treatment remains unclear. Research into molecular profiles and validation of prognostic or predictive biomarkers will be required to identify the patient subsets most likely to experience meaningful benefit from this important class of agents.

Targeting Programmed Cell Death -1 (PD-1) and Ligand (PD-L1): A new era in cancer active immunotherapy

Improved understanding of the immune system and its role in cancer development and progression has led to impressive advances in the field of cancer immunotherapy over the last decade. Whilst the field is rapidly evolving and the list of drugs receiving regulatory approval for the treatment of various cancers is fast growing, the group of PD1- PDL-1 inhibitors is establishing a leading role amongst immunomodulatory agents. PD1- PDL-1 inhibitors act against pathways involved in adaptive immune suppression resulting in immune checkpoint blockade. Within the last four years two PD-1 and three PD-L1 inhibitors have been utilized in clinical practice against a variety of malignancies. Focus was initially placed on targeting cancers considered immunogenic such as melanoma, renal and lung cancers but subsequently the application expanded to include amongst others Hodgkin Lymphoma, urothelial as well as head and neck cancer. This article provides a comprehensive review of the early and late phase trials that led to the regulatory approval of all five PD1- PDL-1 inhibitors in the corresponding cancer types. It presents available data on the combinations of PD1- PDL-1 inhibitors with other therapies (immunotherapy, targeted therapy and chemotherapy), the toxicity profile of the PD1- PDL-1 inhibitors and ongoing trials testing the efficacy of these agents in cancer types beyond those that have been addressed already. Finally, current and future challenges in the application of PD-1 and PD-L1 inhibitors are discussed with emphasis on the role of predictive biomarkers.

Review article: systemic treatment of hepatocellular carcinoma

BACKGROUND

The approval of the tyrosine kinase inhibitor sorafenib in 2007 marked a milestone in the treatment of hepatocellular carcinoma, as sorafenib was the first systemic therapy to show a survival benefit in patients with advanced hepatocellular carcinoma. Since then many drugs failed in the first- and second-line setting and it took almost another decade until further tyrosine kinase inhibitors succeeded in phase III trials.

AIM

To summarise the evolving field of systemic therapy of hepatocellular carcinoma.

METHODS

We reviewed recently published studies identified from PubMed and data presented at recent meetings. Main search terms included hepatocellular carcinoma, tyrosine kinase inhibitors, immunotherapy, immune checkpoint inhibitors, sorafenib, regorafenib, lenvatinib, cabozantinib, ramucirumab, and nivolumab.

RESULTS

We discuss the evolution of targeted therapies since the approval of sorafenib including failures and recent advances. We also elaborate the unmet need of biomarkers to guide treatment decisions and discuss the emerging field of immunotherapy in hepatocellular carcinoma.

CONCLUSIONS

The tyrosine kinase inhibitors sorafenib (first line) and regorafenib (second line) have been approved for hepatocellular carcinoma, and the immune checkpoint inhibitor nivolumab obtained conditional approval for sorafenib-experienced patients in the United States. With lenvatinib in the first line, and cabozantinib and ramucirumab in sorafenib-experienced patients, three more targeted therapies reached their primary endpoint in phase III trials and may soon be added to the treatment armamentarium.

Long-term remission in advanced stage hepatocellular carcinoma? A chance for cure?

Liver resection, transplantation, and local ablation are potential curative treatment options but can only be offered to patients with early stage hepatocellular carcinoma (HCC). Patients with macrovascular tumor invasion and extrahepatic metastases are candidates for palliative systemic therapies. Achieving radiological complete response can be associated with long-term remission and excellent outcome. However, despite recent advancements in the medical treatment of advanced stage HCC, complete remission with available systemic treatment options still remains a rare event. This review summarizes data on radiological complete response to systemic therapies and discusses issues that may complicate the goal of achieving cure in advanced stage HCC.

Pembrolizumab in patients with advanced hepatocellular carcinoma previously treated with sorafenib (KEYNOTE-224): a non-randomised, open-label phase 2 trial

BACKGROUND

Immune checkpoint blockade therapy has shown promising results in patients with advanced hepatocellular carcinoma. We aimed to assess the efficacy and safety of pembrolizumab in this patient population.

METHODS

KEYNOTE-224 is a non-randomised, multicentre, open-label, phase 2 trial that is set in 47 medical centres and hospitals across ten countries. Eligible patients had pathologically confirmed hepatocellular carcinoma; had previously been treated with sorafenib and were either intolerant to this treatment or showed radiographic progression of their disease after treatment; an Eastern Cooperative Oncology Group performance status of 0-1; adequate organ function, and were Child-Pugh class A. Participants received 200 mg pembrolizumab intravenously every 3 weeks for about 2 years or until disease progression, unacceptable toxicity, patient withdrawal, or investigator decision. The primary endpoint was objective response, defined as the proportion of patients with complete or partial response in all patients who received at least one dose of pembrolizumab, which was radiologically confirmed by use of the Response Evaluation Criteria in Solid Tumors version 1.1 by central review. Safety was also assessed in all treated patients. This trial is ongoing but closed to enrolment and is registered with ClinicalTrials.gov number NCT02702414.

FINDINGS

Between June 7, 2016, and Feb 9, 2017, we screened 169 patients with advanced hepatocellular carcinoma, of whom 104 eligible patients were enrolled and treated. As of data cutoff on Feb 13, 2018, 17 (16%) patients were still receiving pembrolizumab. We recorded an objective response in 18 (17%; 95% CI 11-26) of 104 patients. The best overall responses were one (1%) complete and 17 (16%) partial responses; meanwhile, 46 (44%) patients had stable disease, 34 (33%) had progressive disease, and six (6%) patients who did not have a post-baseline assessment on the cutoff date were considered not to be assessable. Treatment-related adverse events occurred in 76 (73%) of 104 patients, which were serious in 16 (15%) patients. Grade 3 treatment-related events were reported in 25 (24%) of the 104 patients; the most common were increased aspartate aminotransferase concentration in seven (7%) patients, increased alanine aminotransferase concentration in four (4%) patients, and fatigue in four (4%) patients. One (1%) grade 4 treatment-related event of hyperbilirubinaemia occurred. One death associated with ulcerative oesophagitis was attributed to treatment. Immune-mediated hepatitis occurred in three (3%) patients, but there were no reported cases of viral flares.

INTERPRETATION

Pembrolizumab was effective and tolerable in patients with advanced hepatocellular carcinoma who had previously been treated with sorafenib. These results indicate that pembrolizumab might be a treatment option for these patients. This drug is undergoing further assessment in two phase 3, randomised trials as a second-line treatment in patients with hepatocellular carcinoma.

FUNDING

Merck & Co, Inc.

Immune checkpoint blockade in advanced hepatocellular carcinoma: an update and critical review of ongoing clinical trials

Systemic treatments for advanced hepatocellular carcinoma (HCC) are evolving rapidly and several multi-targeted tyrosine kinase inhibitors have demonstrated a survival advantage over best supportive care. Despite these treatment advances, the majority of HCC patients will progress on tyrosine kinase inhibitor therapy. Preclinical data indicate that interference with immune checkpoint molecules results in HCC growth suppression. Several clinical trials applying monoclonal antibodies to immune checkpoint molecules have demonstrated durable antitumor activity in advanced HCC patients. As such, pivotal clinical trials are now in progress to assess if these agents will alter the natural history of the disease and further extend the overall survival of advanced HCC patients. This manuscript will review the current status of immune checkpoint blockade in patients with advanced HCC.

Biomarker-Driven and Molecular Targeted Therapies for Hepatobiliary Cancers

The recent accumulation of molecular profiling data for primary hepatobiliary malignancies, including hepatocellular carcinoma and biliary tract cancers, has led to a proliferation of promising therapeutic investigations in recent years. Treatment with pathway-specific targeted inhibitors and immunotherapeutic agents have demonstrated promising early clinical results. Key molecular alterations in common hepatobiliary cancers and ongoing interventional clinical trials of molecularly targeted systemic agents focusing on hepatocellular carcinoma and biliary tract cancer are reviewed.