Emerging Therapies for Hepatocellular Carcinoma (HCC)

SIMPLE SUMMARY: Primary liver cancer, also known as Hepatocellular carcinoma (HCC), is considered to be a major global health challenge. Due to delays in diagnosis at early asymptomatic stages, HCC reaches a severe aggressive stage, thereby having a significant negative impact on patient survival. In addition, HCC shows marked resistance to conventional cancer treatments such as chemo- and radiotherapy. A variety of new and advanced therapies are continuously being evaluated to acquire a breakthrough in HCC treatment to enhance overall and recurrence-free survival. Appropriate identification and selection of target genes and utilization of safe and effective therapeutic approaches, such as gene therapy or immunotherapy, are key strategies for the effective treatment for HCC. This review paper intends to provide a perspective on emerging approaches as avenues towards more effective and safer therapies for HCC. ABSTRACT: Hepatocellular carcinoma (HCC) arises from hepatocytes and accounts for 90% of primary liver cancer. According to Global Cancer Incidence, Mortality and Prevalence (GLOBOCAN) 2020, globally HCC is the sixth most common cancer and the third most common cause of cancer-related deaths. Reasons for HCC prognosis remaining dismal are that HCC is asymptomatic in its early stages, leading to late diagnosis, and it is markedly resistant to conventional chemo- and radiotherapy. Liver transplantation is the treatment of choice in early stages, while surgical resection, radiofrequency ablation (RFA) and trans arterial chemoembolization (TACE) are Food and Drug Administration (FDA)-approved treatments for advanced HCC. Additional first line therapy for advanced HCC includes broad-spectrum tyrosine kinase inhibitors (TKIs), such as sorafenib and lenvatinib, as well as a combination of immunotherapy and anti-angiogenesis therapy, namely atezolizumab and bevacizumab. However, these strategies provide nominal extension in the survival curve, cause broad spectrum toxic side effects, and patients eventually develop therapy resistance. Some common mutations in HCC, such as in telomerase reverse transcriptase (TERT), catenin beta 1 (CTNNB1) and tumor protein p53 (TP53) genes, are still considered to be undruggable. In this context, identification of appropriate gene targets and specific gene delivery approaches create the potential of gene- and immune-based therapies for the safe and effective treatment of HCC. This review elaborates on the current status of HCC treatment by focusing on potential gene targets and advanced techniques, such as oncolytic viral vectors, nanoparticles, chimeric antigen receptor (CAR)-T cells, immunotherapy, and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9), and describes future prospects in HCC treatment.