Potential experimental immune checkpoint inhibitors for the treatment of cancer of the liver

Introduction: Traditional systemic therapies offer limited benefit for advanced cancers of the liver. Immune checkpoints are inhibitory regulators of the immune system and the success of immune checkpoint inhibitors (ICIs) in the treatment of other cancers has led to clinical trials investigating the use of ICIs alone or in combination with other therapies for liver cancers.Area covered: Clinical trials involving ICIs for the treatment of liver cancer were broadly reviewed. Hepatocellular carcinoma and intrahepatic cholangiocarcinoma were examined. Phase I/II trials were prioritized, and relevant phase III trials were discussed. MEDLINE, PubMed, ASCO meeting library, and Web of Science databases were searched with the keywords 'immune checkpoint inhibitor' or 'targeted therapy' in combination with 'hepatocellular carcinoma,' or 'intrahepatic cholangiocarcinoma'. Major outcomes were safety and efficacy defined by response rate, progression-free survival, or overall survival.Expert opinion: ICIs can improve progression-free and overall survival among patients with advanced disease with an acceptable safety profile. Given the heterogeneity of liver disease, ideal strategies will likely include a combination of ICIs with additional therapies to achieve the most robust and durable response. Additional biomarkers will be needed to guide combination therapy to personalize treatment regimen for patients with primary liver cancers.

The Evolving Role of Immune Checkpoint Inhibitors in Hepatocellular Carcinoma Treatment

Hepatocellular carcinoma (HCC) is one of most common cancers and the fourth leading cause of death worldwide. Commonly, HCC development occurs in a liver that is severely compromised by chronic injury or inflammation. Liver transplantation, hepatic resection, radiofrequency ablation (RFA), transcatheter arterial chemoembolization (TACE), and targeted therapies based on tyrosine protein kinase inhibitors are the most common treatments. The latter group have been used as the primary choice for a decade. However, tumor microenvironment in HCC is strongly immunosuppressive; thus, new treatment approaches for HCC remain necessary. The great expression of immune checkpoint molecules, such as programmed death-1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), lymphocyte activating gene 3 protein (LAG-3), and mucin domain molecule 3 (TIM-3), on tumor and immune cells and the high levels of immunosuppressive cytokines induce T cell inhibition and represent one of the major mechanisms of HCC immune escape. Recently, immunotherapy based on the use of immune checkpoint inhibitors (ICIs), as single agents or in combination with kinase inhibitors, anti-angiogenic drugs, chemotherapeutic agents, and locoregional therapies, offers great promise in the treatment of HCC. This review summarizes the recent clinical studies, as well as ongoing and upcoming trials.

Biomarkers in Immunotherapy-Based Precision Treatments of Digestive System Tumors

Immunotherapy, represented by immune checkpoint inhibitors (mainly referring to programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) blockades), derives durable remission and survival benefits for multiple tumor types including digestive system tumors [gastric cancer (GC), colorectal cancer (CRC), and hepatocellular carcinoma (HCC)], particularly those with metastatic or recurrent lesions. Even so, not all patients would respond well to anti-programmed death-1/programmed death-ligand 1 agents (anti-PD-1/PD-L1) in gastrointestinal malignancies, suggesting the need for biomarkers to identify the responders and non-responders, as well as to predict the clinical outcomes. PD-L1expression has increasingly emerged as a potential biomarker when predicting the immunotherapy-based efficacy; but regrettably, PD-L1 alone is not sufficient to differentiate patients. Other molecules, such as tumor mutational burden (TMB), microsatellite instability (MSI), and circulating tumor DNA (ctDNA) as well, are involved in further explorations. Overall, there are not still no perfect or well-established biomarkers in immunotherapy for digestive system tumors at present as a result of the inherent limitations, especially for HCC. Standardizing and harmonizing the assessments of existing biomarkers, and meanwhile, switching to other novel biomarkers are presumably wise and feasible.

Overview of Current Progress in Immune Checkpoint Inhibitor Therapy for Advanced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) remains to a common cause of tumor mortality worldwide and represents the most common type of lethal hepatic malignancy. The incidence of HCC is swiftly increasing in western countries and southeast Asia. Despite poor prognosis, traditional treatments for advanced HCC appear to be minimally effective or even useless since patients are usually diagnosed in the advanced stage of disease. In recent years, immune checkpoint blockade has shown promising results in multiple pre-clinical and clinical trials of different solid tumors, including advanced HCC. Novel drugs targeting immune checkpoints, such as nivolumab (anti-PD-1), durvalumab (anti-PD-L1), and tremelimumab (anti-CTLA-4) have been shown to be highly effective and relatively safe in monotherapy or in combination treatment of advanced liver cancer. Unlike other immunotherapies, this approach can rouse human anti-tumor immunity by relieving T-cell exhaustion and inhibiting the evasion of HCC by blocking co-inhibitory signaling transduction accurately. In this review, we will provide current knowledge of several major immune checkpoints and summarize recent data from clinical trials that applied immune checkpoint inhibitors alone or in combination. In addition, this review will discuss the limitations and future prospective of immune checkpoint-targeted therapy for advanced HCC.

Rationale of Immunotherapy in Hepatocellular Carcinoma and Its Potential Biomarkers

Hepatocellular carcinoma (HCC), the most common type of liver cancer, is derived mostly from a background of chronic inflammation. Multiple immunotherapeutic strategies have been evaluated in HCC, with some degree of success, particularly with immune checkpoint blockade (ICB). Despite the initial enthusiasm, treatment benefit is only appreciated in a modest proportion of patients (response rate to single agent ~20%). Therapy-induced immune-related adverse events (irAEs) and economic impact are pertinent considerations with ICB. It is imperative that a deeper understanding of its mechanisms of action either as monotherapy or in combination with other therapeutic agents is needed. We herein discuss the latest developments in the immunotherapeutic approaches for HCC, the potential predictive biomarkers., and the rationale for combination therapies. We also outline promising future immunotherapeutic strategies for HCC patients.

Immune checkpoint inhibitors for hepatocellular carcinoma

The position of immunotherapy as a pillar of systemic cancer treatment has been firmly established over the past decade. Immune checkpoint inhibitors are a welcome option for patients with different malignancies. This is in part because they offer the possibility of durable benefit, even for patients who have failed other treatment modalities. The recent demonstration that immunotherapy is effective for patients with hepatocellular carcinoma (HCC) is a milestone in the history of this recalcitrant disease. The treatment of HCC has been a challenge, and for many years was limited to the tyrosine kinase inhibitor sorafenib and to several novel tyrosine kinase inhibitors that have shown efficacy and have been approved. The current role of immune checkpoint inhibitors in the management of HCC, and how this role is likely to evolve in the years ahead, are key. Other than efforts evaluating single checkpoint inhibitors, potential combination strategies, including combinations with existing local and systemic approaches, including novel therapies are evolving. This is understandably of special interest considering the potential unique immune system of the liver, which may impact the use of immunotherapy in patients with HCC going forward, and how can it be enhanced further.

The potential combinational immunotherapiesfor treatment of hepatocellular carcinoma

The treatment choices available for hepatocellular carcinoma (HCC) are limited and unsatisfactory. Recent improvements in our understanding of the mechanism involving immune checkpoints, including programmed cell death protein 1 (PD1), programmed death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and also progress in the development of medicines make immunotherapy a promising approach to the treatment of numerous cancers, especially HCC. However, around 40% of patients still suffer from a progressive disease when treated with a monotherapy. Several clinical trials applying a combination therapy including immune checkpoint inhibitors have demonstrated the durable antitumor activity of these approaches in HCC patients. These clinical trials were done with the intent of evaluating the safety of these combination therapies, as well as whether they help improve the overall survival of patients. This study reviewed the recent progress in the use of combination therapies including immunotherapy in treating patients with HCC.

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.