From the University of Alabama at Birmingham, Division of Hematology Oncology, Birmingham, AL, and the University of South Alabama, Division of Hematology Oncology, Mobile, AL. Dr. Paluri and Dr. Hatic contributed equally to this article.
Abstract
- Objective: To review systemic treatment options for patients with locally advanced unresectable hepatocellular carcinoma (HCC).
- Methods: Review of the literature.
- Results: The paradigm of what constitutes first-line treatment for advanced HCC is shifting. Until recently, many patients with advanced HCC were treated with repeated locoregional therapies, such as transartertial embolization (TACE). However, retrospective studies suggest that continuing TACE after refractoriness or failure may not be beneficial and may delay subsequent treatments because of deterioration of liver function or declines in performance status. With recent approvals of several systemic therapy options, including immunotherapy, it is vital to conduct a risk-benefit assessment prior to repeating TACE after failure, so that patients are not denied the use of available systemic therapeutic options due to declined performance status or organ function from these procedures. The optimal timing and the sequence of systemic and locoregional therapy must be carefully evaluated by a multidisciplinary team.
- Conclusion: Randomized clinical trials to improve patient selection and determine the proper sequence of treatments are needed. Given the heterogeneity of HCC, molecular profiling of the tumor to differentiate responders from nonresponders may elucidate potential biomarkers to effectively guide treatment recommendations.
Keywords: liver cancer; molecular therapy; immunotherapy.
Hepatocellular carcinoma (HCC) represents 90% of primary liver malignancies. It is the fifth most common malignancy in males and the ninth most common in females worldwide.1 In contrast to other major cancers (colon, breast, prostate), the incidence of and mortality from HCC has increased over the past decade, following a brief decline between 1999 and 2004.2 The epidemiology and incidence of HCC is closely linked to chronic liver disease and conditions predisposing to liver cirrhosis. Worldwide, hepatitis B virus infection is the leading cause of liver cirrhosis and, hence, HCC. In the United States, 50% of HCC cases are linked to hepatitis C virus (HCV) infection. Diabetes mellitus and alcoholic and nonalcoholic steatohepatitis are the other major etiologies of HCC. Indeed, the metabolic syndrome, independent of other factors, is associated with a 2-fold increase in the risk of HCC.3
Although most cases of HCC are predated by liver cirrhosis, in about 20% of patients HCC occurs without liver cirrhosis.4 Similar to other malignancies, surgery in the form of resection (for isolated lesions in the context of good liver function) or liver transplant (for low-volume disease with mildly impaired liver function) provides the best chance of a cure. Locoregional therapies involving hepatic artery–directed therapy are offered for patients with more advanced disease that is limited to the liver, while systemic therapy is offered for advanced unresectable disease that involves portal vein invasion, lymph nodes, and distant metastasis. The Barcelona Clinic Liver Cancer (BCLC) staging system is the most widely used for staging and treatment in HCC. It not only considers the size of the tumor, but also incorporates the degree of liver dysfunction and the patient’s functional status.5,6
Molecular Pathogenesis
Similar to other malignancies, a multistep process of carcinogenesis, with accumulation of genomic alterations at the molecular and cellular levels, is recognized in HCC. In about 80% of cases, repeated and chronic injury, inflammation, and repair lead to a distortion of normal liver architecture and development of cirrhotic nodules. Exome sequencing of HCC tissues has identified risk factor–specific mutational signatures, including those related to the tumor microenvironment, and defined the extensive landscape of altered genes and pathways in HCC (eg, angiogenic and MET pathways).7 In the Schulze et al study, the frequency of alterations that could be targeted by available Food and Drug Administration (FDA)–approved drugs comprised either amplifications or mutations of FLTs (6%), FGF3 or 4 or 19 (4%), PDGFRs (3%), VEGFA (1%), HGF (3%), MTOR (2%), EGFR (1%), FGFRs (1%), and MET (1%).7 Epigenetic modification of growth-factor expression, particularly insulin-like growth factor 2 and transforming growth factor alpha, and structural alterations that lead to loss of heterozygosity are early events that cause hepatocyte proliferation and progression of dysplastic nodules.8,9 Advances in whole-exome sequencing have identified TERT promoter mutations, leading to activation of telomerase, as an early event in HCC pathogenesis. Other commonly altered genes include CTNNB1 (B-Catenin) and TP53. As a group, alterations in the MAP kinase pathway genes occur in about 40% of HCC cases.
Actionable oncogenic driver alterations are not as common as tumor suppressor pathway alterations in HCC, making targeted drug development challenging.10,11 The FGFR (fibroblast growth factor receptor) pathway, which plays a critical role in carcinogenesis-related cell growth, survival, neo-angiogenesis, and acquired resistance to other cancer treatments, is being explored as a treatment target.12 The molecular characterization of HCC may help with identifying new biomarkers and present opportunities for developing therapeutic targets.