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“Hepatocellular carcinoma: A life-threatening disease”
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Biomedicine & Pharmacotherapy xxx (2016) xxx–xxx
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“Hepatocellular carcinoma: A life-threatening disease” Shinu Chacko* , Subir Samanta Division of Pharmaceutical Chemistry, Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
A R T I C L E I N F O
Article history: Received 11 September 2016 Received in revised form 13 October 2016 Accepted 26 October 2016 Keywords: Hepatocellular carcinoma Transarterial chemoembolization Molecular targeted therapy Personalized medicine Immunotherapy Peptide hybrid
A B S T R A C T
An estimated rise in liver cancer incidence will increase to 95374 new cases by 2020. Hepatocellular Carcinoma (HCC), the most common primary malignant tumour of the liver, is considered to be the third leading cause of all cancer-related deaths and fifth common cancer worldwide. The reported data shows that the rate of HCC incidence in male population is three to four times higher compared with the female population. In the United States, HCV-induced liver cancer is increasing very fast because of the lack of proper treatment option. There are various treatment strategies available for HCC like liver transplantation, resection, ablation, embolization and chemotherapy still the prognosis is destitute. If the patient is eligible, liver transplantation is the only therapeutic option that may give around 90% survival rate, but the scarcity of liver donor limits its broad applicability. A sudden address is necessary to develop specific drugs, personalized medicine, for HCC. ã 2016 Elsevier Masson SAS. All rights reserved.
Contents 1. 2.
3.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hepatocellular carcinoma (HCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Risk factors and mechanism of hepatocarcinogenesis . . . . . . . . . . . . . . . . . . 2.1. Epidemiology of HCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Treatment strategies for HCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Surgical resection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4. Liver transplantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5. Percutaneous ablation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6. Transarterial embolization (TAE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7. Immunotherapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8. Molecular targeted chemotherapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9. Checkpoint 1 and VEGFR: promising targets for anti-HCC drug development 2.10. Anti-cancer potential of small peptides and its hybrids . . . . . . . . . . . . . . . . . 2.11. Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1. Introduction Abbreviations: ADME, absorption distribution metabolism and excretion; AFP, alpha-fetoprotein; BCLC, Barcelona Clinic Liver Cancer; Chk 1, check point 1; HBV, Hepatitis B Virus; HCC, hepatocellular carcinoma; HCV, Hepatitis C Virus; LT, liver transplatation; NAFLD, nonalcoholic fatty liver disease; PDGF, platelet-derived growth factor; PS, performance status; TACE, transarterial chemoembolization; TSC, thiosemicarbazide; VEGFR, vascular endothelial growth factor receptors. * Corresponding author. E-mail address: [email protected] (S. Chacko).
Cancer develops when normal cells become abnormal, and the abnormal cells keep dividing and forms a lumps (tumours). All tumours are not cancerous, cancerous tumours (malignant) can grow into nearby tissues and may spread through blood or lymphatic system from the site where it originated (primary
http://dx.doi.org/10.1016/j.biopha.2016.10.078 0753-3322/ã 2016 Elsevier Masson SAS. All rights reserved.
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Fig. 1. Internal Anatomy of the liver.
cancer) to the other parts of the body and developed new cancerous tissue (secondary cancer or metastasis). The liver is the largest, lobed, glandular organ in the body. The internal anatomy of the liver is depicted in Fig. 1. The parenchymal tissue of the liver mainly consists of hepatocytes. Liver aids in digestion by producing biochemicals, store energy, protein synthesis and detoxification. The liver is getting perfusion at the rate of 85 mL/min/100 g of tissue which is 24% of total cardiac output. Most of the drugs are metabolized primarily in the liver with the help of enzymes and bile produced by the liver. Any diseases or injury to the liver may lead to impairment of these process and lead to the accumulation of toxic compounds in the body [1]. The primary liver cancer originates in the liver and its occurrence is increasing rapidly in every year. Worldwide, liver cancer is the sixth most common cancer (782451 new cases), the 2nd cause of cancer-related death (745,533 cases), and accounts for 5.6% of all cancers as per the data published in Globocan 2012
(Fig. 2). In 2020, it is estimated that liver cancer incidence will be rise to 95374 new cases [2] (Fig. 3). Among the various types of primary liver cancers like hepatocellular carcinoma (HCC), cholangiocarcinoma, angiosarcoma, hepatoblastoma, fibrosarcoma, leiomyosarcoma and rhabdomyosarcoma, HCC occupies major portion. 2. Hepatocellular carcinoma (HCC) Hepatocellular Carcinoma (HCC), also called malignant hepatoma, is a primary malignant tumour of the liver arising from the liver cells (hepatocytes). HCC is considered to be the third leading cause of all cancer-related deaths and fifth common cancer worldwide [3]. It accounts for around 80–90% of all liver cancers. Globally, the occurrence of HCC is increasing by 3–9% annually [4] and approximately 7.5 Lakhs of new cases of HCC occurs per year [5]. More than half a million people are diagnosed with HCC worldwide, including about 20,000 new cases in the United States,
Fig. 2. Estimated number of cancer incidence worldwide, all ages both sexes. Source: http://globocan.iarc.fr/old/pie_pop.asp?selection=224900&title=World&sex=0&type=0&window=1&join=1&submit=%C2%A0Execute accessed on 31-08-2016
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Fig. 3. Predicted liver cancer incidence worldwide all ages in 2020. Source: http://globocan.iarc.fr/old/burden.asp?selection_pop=224900&Textp=World&selection_cancer=14070&Textc=Liver&pYear=8&type=0&window=1&submit=%C2% A0Execute accessed on 31-08-2016
in each year. The male population are more prone to the liver cancer than female population [6]. 2.1. Risk factors and mechanism of hepatocarcinogenesis Nearly all HCC occurs in the presence of cirrhosis or advanced fibrosis. Thus, any cause of liver disease that can result in cirrhosis should be considered a potential risk factor for HCC. The distribution of risk factors in patients with HCC depends on the ethnic group, race or geographical region. The various common risk factors are;
Infection with Hepatitis B virus (HBV) or Hepatitis C virus (HCV) Alcoholic liver diseases Non-alcoholic fatty liver Aflatoxins
In Africa and East Asian countries including Taiwan, China, and Korea, HBV is the primary cause, whereas, in the West and Japan, HCV is the main risk factor, together with other causes of cirrhosis and alcoholism. The appropriate proportions of causes of HCC in the USA is tabulated in Table 1. Most of the risk factors favour development and progression of cirrhosis which is present in maximum cases of HCC [7]. Worldwide, infection with HBV is the primary reason for HCC in half of the patients, and it can cause HCC without cirrhosis. The factors which increase the risk of developing HCC in persons with HCV infection are sex, olde age, co-infection with human immunodeficiency virus (HIV) or HCB, diabetes or obesity.
Continued chronic use of alcohol (40–60 g of alcohol daily) is also a well-defined risk factor for HCC through the development of cirrhosis. Persons co-infected with HCV is more prone to HCC in combination with the heavy use of alcohol than in HCB coinfection [8]. Nonalcoholic fatty liver disease (NAFLD), which is present commonly in up to 90% of all obese persons and up to 70% of individuals with type 2 diabetes, has been proposed as a possible risk factor for hepatocellular carcinoma [9]. NAFLD is a group of conditions including mild hepatic steatosis and non-alcoholic steatohepatitis. In these circumstances, fat builds up in the liver. The fat causes inflammation and damage, which may lead to cirrhosis. Generally, all the risk factors transform healthy liver to HCC liver through fibrosis and cirrhosis (Fig. 4). The understanding of the mechanism involved in hepatocarcinogenesis (Fig. 5) is crucial for the development of new treatment. Hepatocarcinogenesis is a highly complex multistep process, and no single dominant or pathognomonic molecular mechanism exists in HCC. It starts from hepatic stem cells or mature hepatocytes under the condition of chronic liver disease initiated by oxidative stress, chronic inflammation and cell death followed by unrestricted proliferation/restricted regeneration and permanent liver remodelling. The chronic liver injury caused by HBV and HCV infection, chronic consumption of alcohol, nonalcoholic steatohepatitis and fatty liver, hereditary hemochromatosis, and primary biliary cirrhosis causes permanent hepatocyte damage. In response to cytokine stimulation caused by hepatocyte injury, an enormous compensatory cell proliferation and regeneration takes place followed by fibrosis and cirrhosis, particularly driven by the
Table 1 Approximate proportions of causes of hepatocellular carcinoma in the USA. Causes A) Chronic viral infections Hepatitis C Hepatitis B Hepatitis C + alcohol Both B) Other causes of cirrhosis Alcohol Cryptogenic Others (hemochromatosis, alpha-1 antitrypsin deficiency, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis, and nonalcoholic steatohepatitis) No cirrhosis or virus
Percentage 47–55 15–17 27 or above 2–5 9 7 6
4
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Fig. 4. Process involved in the transformation of healthy liver into Hepatocellular Carcinoma (HCC). Adapted from S. Chacko and S. Samanta, Computer Aided Drug Design [10].
synthesis of extracellular matrix components from hepatic stellate cells. Finally, in this carcinogenic environment hyperplastic and dysplastic nodules forms and normal liver tissue transforms to the cancerous. The molecular pathogenesis of HCC involves different genetic/epigenetic aberrations and alterations in multiple signalling pathways leading to the known heterogeneity of the disease concerning its biologic and clinical behaviour [12]. 2.2. Epidemiology of HCC Liver cancer incidence and death rates are increasing in many parts of the world, including North America, Latin America, and Central Europe. Liver cancer incidence rates were increased by 3.1% every year from 2008 to 2012 according to National Cancer Institute Surveillance, Epidemiology and End Results (SEER) Database of the National Cancer Institute in the US [13]. The incidence was three time's higher in men compared with women (11.5 versus 3.9 per 100,000). The rise in liver cancer incidence rate among non-Hispanic whites, non-Hispanic blacks, and American Indian/Alaska Natives, and a decline in non-Hispanic Asians and Pacific Islanders during this period may be related to the increasingly widespread vaccination of children against hepatitis B viral infection, the dominant HCC-related virus among Asian/
Pacific Islanders. In contrast to the falling death rates seen for all other common cancers like lung, breast, and prostate cancers, mortality from liver cancer in men increased by 2.8% every year [14], and for women, it rose by 3.4% annually [13,15,16]. In India, information on HCC is not sufficient, and data provided by the cancer registries are not accurate because of the poor reporting and diagnosing system and the patients who are diagnosed and treated for HCC by the speciality like Gastroenterology/Hepatology/Transplant Surgery/G.I. Surgery are not listed in the registries [5]. National cancer registry program (NCRP) was established in 1981 by Indian council of medical research (ICMR) to analyse and evaluate various cancer incidence in India statistically. Initially, three hospital-based cancer registries (HBCRs) and three population-based cancer registries (PBCRs) were established. By now, 27 PBCRs and more than 30 HBCRs have been established. The latest published registry data by ICMR was available in the cancer registry website (ncrpindia.org) from March 2016, which provides information on various cancers from 2012 to 2014 [17]. As per the latest NCRP data based on male population (Table 2), out of 27 PBCRs, 19 centres reported liver cancer in the first ten ranking and among 19, Sikkim, Naharlagun and Pasighat have reported liver cancer in the second position. In comparison with previous data published (2009–2011), incidence and mortality of
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Fig. 5. The suspected mechanisms of hepatocarcinogenesis for the various risk factors Adapted from P.A. Farazi et al. Cancer [11].
liver cancer have increased gradually, and the overall impact is higher in male population [18].
Radiation Targeted therapy Chemotherapy
2.3. Treatment strategies for HCC The treatment of liver cancer depends on many factors like the stage (extent) of cancer and how well the liver is working, age, the general state of health, and personal preferences. The Barcelona Clinic Liver Cancer (BCLC) classification (Fig. 6), widely accepted HCC staging system, links HCC with the patient’s performance status (PS) and cancer-related symptoms. This staging system differentiates early stage cancer with an advanced stage so as to diagnose HCC in the early stage and to select proper treatment option [19]. The treatment strategies are broadly divided into curative and palliative treatment. Curative treatments are applied to the HCC patients who are in very early or early stages, and palliative care provided to the patients in advanced stage HCC. Based on the different stages, treatment options may include: Curative treatments
2.4. Surgical resection It is the treatment choice, especially in Asian countries [6], for patients with HCC in the very early stage and without cirrhosis. In the case of Cirrhotic patients selection should be done by tumour size, liver function, portal hypertension and total bilirubin level for their eligibility for resection. Such HCC patients having single tumour of size less than 3 cm, well-preserved liver function, normal portal hypertension (a hepatic venous pressure gradient greater than 10 mm of Hg) moreover, normal total bilirubin level (1 mg per deciliter) achieves good results after resection even in cirrhotic condition, and they may have a survival rate of 70% in five years. The biggest problem with resection is the chances of getting liver failure, so strict selection should be made [20]. 2.5. Liver transplantation
Surgery (Resection or liver transplant) Other local treatments, such as ablation or embolization Palliative treatments
In unresectable HCC associated with cirrhosis, liver transplantation (LT) is the best curative treatment [21] with high survival rate and lowest recurrence chance. The main advantage of LT is that
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Table 2 Population-based cancer registry of liver cancer in male population during 2012-14 in India [18]. ‘X’ indicates not in first ten positions. PBCRs
Total Population (Male)
Total cancer
Liver cancer in male
Liver cancer in female
Bangalore Barshi Rural Barshi expanded Bhopal Chennai Delhi Mumbai Cachar Dibrugarh Kamrup Manipur Mizoram Sikkim Ahmedabad Aurangabad Kolkata Kollam Nagpur Pune Trivandrum Meghalaya Tripura Nagaland Wardha Naharlagun Pasighat Patiala
8,885,498 (4,616,478) 1,518,132 (7,98,979) 43,28,959 (22,579,96) 4,019,413 (2,088,045) 9,409,435 (4,715,650) 16,896,984 (9,012,555) 12,506,206 (6,728,832) 5,438,912 (2,076,093) 4,085,263 (2,076,093) 4,082,409 (2,141,950) 9,139,837 (4,600,029) 3,458,396 (1,741,869) 1,884,412 (9952,02) 1,19,03,496 (62,639,52) 38,31,611 (19,80,880) 44,87,332 (23,38,295) 79,42,156 (37,39,048) 51,52,611 (26,20,014) 1,04,33,334 (54,77,270) 99,52,077 (47,53,308) 59,33,041 (29,64,519) 1,13,84,169 (57,99,657) 21,08,595 (10,91,662) 39,486,14 (20,26,323) 24,59,625 (12,56,000) 4,14,016 (2,10,521) 5930509 (3130053)
12624 4308 2032 39757 15258 26333 33230 2539 2521 3256 3969 3380 1155 11844 1888 9038 9030 5422 8594 5755 4248 2612 6330 1361 2730 334 6011
4.3% (7th common) 6.2%*(3rd common) 4.3% (5th common) X 3.9% (7th common) X 5.7% (4th common) X 3.7% (9th common) 3.3% (10th common) 4.1% (7th common) 5.5% (4th common) 7.6% (2ndcommon) X X 3.0% (10th common) 4.7% (4th common) 2.8% (10thcommon) 4.5% (7th common) 4.0% (7thcommon) 2.2% (9th common) 2.6% (10thcommon) 2.9% (9th common) 6.2 (4th common) 19.9% (2ndcommon) 7.4% (2nd common) 3.1% (10th common)
X (not in first 10) X X X X X 2.8% (8th common) X X X X 3.9% (6th common) 5.8% (7thcommon) X X X X X X X X X X 2.3% (9th common) 6.8% (5th common) 3.8% (5th common) X
it not only removes the tumour but also the underlying cirrhosis. The limitation is the availability of compatible liver in the stipulated period, so selection on the basis of predicted success rate play a significant role in determining LT. Living donor LT (LDLT) [22] may be considered as the better alternative for cadaveric LT to increase the availability and to reduce waiting period. Those
candidates following Milan criteria for LT (one nodule less than 5 cm or not more than three nodules of less than 3 cm) achieve 75% overall survival in 5 years and less than 15% tumour recurrence rate [6,23]. A considerable amount of patients is dropping out from the waiting list for LT due to the unavailability of healthy liver for a long
Fig. 6. BCLC staging classification and treatment schedule for HCC. N: nodule; M: Metastasis; PS: Performance status; TACE: Transarterial chemoembolization; BSC: Best supportive care. Adapted from Llovet J. M. et al., Lancet 2003 [20].
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time. By that time candidates complying Milan criteria for LT are becoming disqualified due to tumour progression. So treatment with other options is necessary for those candidates during waiting period to satisfy Milan criteria throughout the waiting period [23]. 2.6. Percutaneous ablation Percutaneous ablation is a choice of treatment for BCLC stage 0 and A unresectable HCC patients and considered as the first line therapy in some parts of Japan [24]. In this technique, inoperable neoplastic cells are destroyed by chemicals like alcohol and acetic acid, or by altering temperature at the tumour site using radiofrequency (RF), laser, or cryoablation. Radiofrequency ablation (RFA) is minimally invasive, can repeatedly be used and have fewer side effects. Applicability of this technique is limited to early stage HCC of less than 2 cm, and it achieves around 40–70% survival rate in 5 years. In RFA a small bipolar or unipolar needle is inserted into the liver and correctly placed into the tumour. RF energy is delivered to the tumour by using RF generator, and tumour cells are destroyed with the help of frictional heat produced by rapid agitation [25]. Reports showed that it is more effective than percutaneous ethanol injection (PEI) and requires fewer treatment sessions [26], but for tumours of less than 2 cm ethanol ablation may produce 90–100 percent response. The main disadvantage of these local therapies are the high rate of recurrence and can only apply to the early stage HCC. However, the fact is that most of the HCC diagnosed are in later stage [12]. 2.7. Transarterial embolization (TAE) TAE is widely accepted palliative treatment option for those who are in the intermediate stage of hepatic carcinoma. In this technique, an embolus, usually gelatin mixed with lipiodol (a radio-opaque contrast agent), is inserted into the blood vessel using a catheter to block the blood supply to the tumour cells. As a principle blockage of hepatic artery results in extensive necrosis of the HCC which are widely vascularized [27]. Sometimes embolus may be included with tumour attacking agents like chemicals
7
(transarterial chemoembolization (TACE), radiation or radiopharmaceuticals (radioembolization) to destroy the cancer cells. Doxorubicin, mitomycin, and cisplatin are used as anticancer agents in embolization method. TACE is a standard care treatment for HCC patients with preserved liver function, asymptomatic multinodular tumours without vascular invasion or extrahepatic spread. It may give 40– 50% 5-year survival rate and achieve 15–62 percent partial response [28]. By the application of TACE, tumour progression may be delayed [22], and this is especially useful for patients who are waiting for LT. The drawback of this technique is the high chances recurrence (around 70% in 5 years) [12]. The intermediate stage HCC patients are heterogeneous and have a different degree of tumour burden, so selective TACE is needed. In this regard, selection of anti-tumour agents, embolizing agent, and radioopaque agents is crucial to the success of this method. The recent advancement in TACE, use of microspheres (drug-eluting beads), overcomes some of the drawbacks mentioned above. Microspheres have the ability to release the incorporated drug, doxorubicin, in a controlled fashion so as to localise drug concentration and to control the amount of drug that reaches systemic circulation [29]. TACE with a drug-eluting bead (DEB-TACE) is a better replacement for conventional lipiodol (ethiodized oil) based TACE. Radioembolization is embolization with radiation. Microspheres or resin beads with radioactive isotope yttrium Y-90 [30] is delivered to the blood vessels that feed the tumour. The size of the beads is around 35 mm but in the case of TACE it is 100– 500 mm, and it causes ischaemia also. Some studies showed that radioembolization is superior to TACE concerning side effect, response rate and time to progression [31] but the cost of the treatment limit its broad accessibility. It also been reported that this is safer in the advanced stage of HCC [32]. 2.8. Immunotherapy Immunotherapy utilizes the innate immune system to recognize the cancer cells and to kill them. HCC is an immunocompromised condition, many of the immunocytes are found to be
Table 3 Trials with active recruitment of molecular-targeted therapies in hepatocellular carcinoma. Adapted from [39]. Drugs
Trial phases
Number of trials
Molecular targets
Sorafenib Bevacizumab Erlotinib Everolimus Brivanib Sunitinib Rapamycin AZD6244 Bortezomib TAC-101 Cediranib Cetuximab Cixutumumab Temsirolimus Linifanib PI-88 ARQ197 BIBF1120 Dasatinib GC33 Gefitinib Lapatinib Licartin Pazopanib Alvocidib
1, 1–2, 2, 3, 4 1, 1–2, 2 1, 1–2, 2, 3 1, 1–2, 2, 3 1, 2, 3 2, 3 1, 2–3, 3 1–2, 2 1, 2 1–2, 2 1, 2 1, 2 1, 2 1, 2 2, 3 2, 3 1, 2 2 2 1 2 2 2, 4 2 1, 2
128 19 15 22 6 10 22 3 3 4 2 2 3 22 2 2 4 2 2 2 2 2 2 4 1
BRAF, VEGFR, PDGFR VEGF EGFR MTORC1 FGFR, VEGFR, PDGFR VEGFR, PDGFR, KIT MTORC1 MEK Proteasome RAR-a VEGFR EGFR IGF-1R MTORC1 VEGF, PDGFR Endo-D-glucuronidase heparinase MET VEGFR, PDGFR, FGFR BCR-ABL GPC3 EGFR EGFR, HER2/neu HAb18G/CD147 VEGFR, PDGFR, KIT Cyclin-dependent kinase
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deficient. Both HBV and HCV infection negatively affects the innate and adaptive mechanism of the immune system in the body [33]. So by the application of immunotherapy, the immune system of the body can be activated and which improves patient's outcome. It produces nontoxic, systemic and long-term anti-cancer activity. Immunotherapy can be differentiated into the following: Immunomodulators and tumour vaccines: In an indirect way these are used to recover the immune response to HCC. Adoptive immunotherapy: In this active immune cells are delivered to destroy cancer cells. As discussed earlier, the main trigger factors for HCC are HBV and HCV. To a large extent the introduction of HBV vaccine eradicate its occurrence and decreases HBV-induced HCC. The research for HCV vaccine is still going on. At the same time, research on the anti-HCC vaccine is also going on. The main limitation for the development of tumour vaccine is the unavailability of tumour specific antigens or tumour-associated antigens (TAA) [34]. Peptide-based anti-HCC vaccines using TAAs like alpha-fetoprotein (AFP) and glypican3 (GPC3) are in clinical trials. An overexpression of GPC3 found in around 80% of HCC and AFP is considered as a useful biomarker of 70–80% of HCC. Many clinical studies targeting these molecules and other biomarkers [35,36] are in different phases and may give suitable candidates for immunotherapy. Adoptive immunotherapy utilizes tumour specific T cells which are grown outside the body and have the ability to kill cancer cells.. The advantages of this method are 1) Specificity: recognize cancer cells from the healthy cell; 2) Ability of T cells for clonal expansion after activation; 3) Able to give effect in metastasis, and 4) Longer days of therapeutic effect due to the T cell’s memory. However, the cost-effectiveness is still a problem and depends on the availability and source of T cells [37]. 2.9. Molecular targeted chemotherapy HCC is heterogeneous in nature both phenotypically and genetically. Each and every patient shows a different kind of tumour characteristics. So single treatment strategy cannot apply to everyone. The understanding of molecular pathogenesis of HCC paves a way to the personalized medicine. Targeting a particular receptor upregulated in HCC helps to reduce the side effects by blocking its action in another receptor. Molecular targeted signalling pathways like mitogen-activated protein kinases (MAPK) pathway (Ras/Raf/MEK/ERK pathway), the Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3k), mammalian target of rapamycin [mTOR] pathway and the canonical Wnt pathway (Wnt/beta-catenin pathway) have been recognized as significant for HCC cell proliferation and angiogenesis. Growth and angiogenic factors/receptors like vascular endothelial growth factor [VEGF], platelet-derived growth factor [PDGF] and particularly epidermal growth factor [EGF] receptor are also overexpressed in HCC. The era of molecular targeted therapy in HCC was started after the success of sorafenib, a multikinase inhibitor, till then there was no single drug available for the first-line treatment of advanced HCC. In November 2007 sorafenib got FDA approval on the basis SHARP trial which compared the efficacy of sorafenib with placebo in advanced HCC. The results showed improvement in median survival and time to progression in comparison with placebo [38]. Orally active sorafenib targets MAPK pathway in HCC and produce anti-angiogenic activity through tyrosine kinases like VEGFR and PDGFR [39]. After the emergence of sorafenib, research in the area of targeted therapy increased. Currently, around 50 agents which aim various targets are in different phases of clinical trial (Table 3).
HCC is a highly vascularized tumour. The drugs which target receptors like VEGF and PDGF may block angiogenesis and proliferation. Bevacizumab, brivanib and ramucirumab are having the anti-angiogenic effect and are under clinical trial. Sorafenib has also shown good effect along with TACE and radio-embolisation. Hypoxic condition generated due to the embolization leads to the expression of VEGF and neovascularization of surviving tumour cells. Sorafenib blocks neovascularization and provides benefits in the treatment [40]. Gadani et al. showed improved overall survival of patients after the use of yttrium-90 treatment along with sorafenib [41]. 2.10. Checkpoint 1 and VEGFR: promising targets for anti-HCC drug development Checkpoint kinase1 (Chk1) [42] (a serine-threonine kinase) and VEGFR-2 [43,44] (a tyrosine kinase) have been identified as the critical targets in the development of an anti-cancer drug against HCC. Yin Xie and co-workers found that the average of Chk1 mRNA level in the liver tumour was 4.14 times higher than the corresponding non-tumour liver tissues [45]. Chk1 protein contains 476 amino acids and gets activated with Deoxyribonucleic Acid (DNA) damage response [42]. It mainly helps damaged DNA to repair at G2 and S phase of cell cycle along with tumour suppressor gene p53. In tumour cells, repairing of damaged DNA through tumour suppressor gene p53 (like in the normal cell) is mutated and purely depends on Chk 1 mediated DNA repair. Inhibition of Chk 1 kinase blocks the total repairing mechanism of damaged DNA in the cancer cell and leads to mitotic cataphoresis and cell death without affecting the normal cell which will repair with the help of p53 gene [46]. VEGFR-2 is also a novel target for the development of anticancer drugs since it is involved in cancer cell proliferation, apoptosis, angiogenesis, invasion and metastasis and is overexpressed in HCC. Inhibition of VEGFR-2 receptor prevents tumour growth through anti-angiogenic effect. Generally, solid tumours are associated with the excess formation of vascular network (angiogenesis) to acquire nutrition necessary for growth and metastasis [47] and which is very fast in HCC [44]. A molecule having both Chk1 and VEGFR-2 inhibitory (multi-targeted) properties may, therefore, be a promising drug candidate for the treatment of HCC without affecting the functions of normal cells. 2.11. Anti-cancer potential of small peptides and its hybrids The evolution of multidrug resistance substantially lowers the success rate of anti-cancer therapy with chemotherapeutic agents. [48]. Investigation for novel strategy is thereby necessary to boost the success rate by limiting drug resistance. Nowadays, the field of anti-cancer drug development is mainly focused on designing of the molecules having target specificity, lesser toxic effects and better differentiation between the tumour cell and normal cell. Most of the currently available anti-cancer drugs do not
Fig. 7. 2D structure of thiosemicarbazide (A) and semicarbazone (B) drawn by Chem. Draw 10.0.
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preferentially accumulate at the tumour site owing to low specificity thereby leading to the incomplete response, increased toxicity and development of drug resistance. Peptides are known to be highly specific to individual protein targets, amenable to site-specific modification and highly selective. However, its low tissue permeability and high susceptibility towards proteolysis limit usage as an oral drug. Amino acids and peptides are taxonomically natural, physiologically nontoxic and chemically multifunctional. Rationalized conjugates of biologically active synthetic agents with amino acids or peptides are hypothesized to be more potent and particularly lesser toxic than their parent biological. Preparing hybrids of an amino acid or peptide with biologically active compounds like thiosemicarbazide (TSC) or semicarbazones tends to stabilize the peptide bond and results in molecules with target specificity [49] and lesser toxicity [50]. TSC and semicarbazones (Fig. 7) are derivatives of thiourea and urea, respectively, wherein one amino group is replaced with hydrazine. They are known to have antiviral [51] and anti-cancer [52,53] activity which usually mediates through binding to Cu and Fe ions in the cells. Thiosemicarbazones being the inhibitors of ribonucleotide reductase arrests the cell cycle at G1/S phase and then inactivates the ribonucleic acid (RNA) synthesis. 3. Concluding remarks Hepatocellular carcinoma is a heterogeneous solid tumour affecting the main detoxifying organ in our body. Chronic liver disease caused by the infection of HCV and HCB is the primary causative agent for HCC. The heterogeneity of the disease makes treatment selection tough. BCLC system of HCC classification helps the physician to check the eligibility of the patients for any available therapies. If the patient is eligible, LT is the best option for the treatment, and it may give success rate of about 90% since LT not only removes cancer but also the underlying liver disease. It is necessary to diagnose the disease in the early stage to treat it efficiently. In the case of HCC till date no diagnostic tool has been developed to detect cancer in the early stage. If this happens, ablation and embolization give better outcome and longer survival rate. All the other treatment option have a high rate of recurrence. Till 2007 there was no first line drug for the advanced stage of HCC. The discovery of sorafenib opens an excellent way to the research on multikinase inhibitors and it still continues. Immunotherapy, another pillar of HCC treatment, improves the natural immunity of the body to fight against HCC. However, it also needs a lot of clinical trials to establish as a promising treatment for HCC. Overall, the available treatment options are insufficient to treat HCC in a systematic way to result in high patient compliance and less chance of recurrence. Now the research is going in a direction to find specific targets, targeted therapy, for HCC through the vast knowledge of molecular mechanism and signalling pathway. Hybrids of peptides with different heterocyclics are the better lead to target HCC cells since peptides are natural molecules and having target specificity and less chance of toxicity. Target specificity is an important aspect to be considered in the development of anti-cancer drugs because it may discard the chance of drug resistance, the main drawback of existing anti-cancer drugs. The Absorption, distribution, metabolism, elimination and toxicity (ADMET) profile can also be improved using peptide hybrids. Consideration of ADMET in the early phase of drug development will reduce the chance of synthesising low bioavailable drugs. Discovery of such target specific molecules for any subgroup of patients will result in the development of personalized medicine.
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Conflict of interest The authors confirm that this article content has no conflict of interest. Acknowledgment The authors are grateful to the University Grants Commission, New Delhi, India, for providing Basic Scientific Research (BSR) fellowship assistance [7-32/2007(BSR)] for the successful completion of this work and also thankful to the Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Jharkhand, India, for giving lab facilities. References [1] C.R. Craig, R.E. Stitzel, Modern Pharmacology with Clinical Applications, 5th ed., Lippincott Williams & Wilkins, 2004. [2] Globocan, Estimated Cancer Incidence, Mortality and Prevalence Worldwide in 2012, Globocan, 2012. (Accessed 31 August 2016). [3] A. Alisi, C. Balsano, Enhancing the efficacy of hepatocellular carcinoma chemotherapeutics with natural anticancer agents, Nutr. Rev. 65 (12) (2007) 550–553. [4] R.F. Velázquez, M. Rodriguez, C.A. Navascues, A. Linares, R. Perez, N.G. Sotorríos, I. Martinez, L. Rodrigo, Prospective analysis of risk factors for hepatocellular carcinoma in patients with liver cirrhosis, Hepatology 37 (3) (2003) 520–527. [5] S.K. Acharya, Epidemiology of hepatocellular carcinoma in India, J. Clin. Exp. Hepatol. 4 (Suppl. 3) (2014) S27–33. [6] H.B. El-Serag, Hepatocellular carcinoma, N. Engl. J. Med. 365 (12) (2011) 1118– 1127. [7] G. Fattovich, T. Stroffolini, I. Zagni, F. Donato, Hepatocellular carcinoma in cirrhosis: incidence and risk factors, Gastroenterology 127 (5) (2004) S35–S50. [8] F. Donato, A. Tagger, U. Gelatti, G. Parrinello, P. Boffetta, A. Albertini, A. Decarli, P. Trevisi, M.L. Ribero, C. Martelli, S. Porru, G. Nardi, Alcohol and hepatocellular carcinoma: the effect of lifetime intake and hepatitis virus infections in men and women, Am. J. Epidemiol. 155 (4) (2002) 323–331. [9] B.A. Neuschwander-Tetri, S.H. Caldwell, Nonalcoholic steatohepatitis: summary of an AASLD single topic conference, Hepatology 37 (5) (2003) 1202–1219. [10] S. Chacko, S. Samanta, Novel thiosemicarbazide hybrids with amino acids and peptides against hepatocellular carcinoma: a molecular designing approach towards multikinase inhibitor, Curr. Comp.-Aided Drug Des. 11 (3) (2015) 279– 290. [11] P.A. Farazi, R.A. DePinho, Hepatocellular carcinoma pathogenesis: from genes to environment, Nat. Rev. Cancer 6 (9) (2006) 674–687. [12] B. Gaetano, D. Shirin, B. Nicoletta, A. Ardiri, Management of hepatocellular carcinoma: an update at the start of 2014, J. Gastrointest. Dig. Syst. 04 (02) (2014). [13] A.B. Ryerson, C.R. Eheman, S.F. Altekruse, J.W. Ward, A. Jemal, R.L. Sherman, S.J. Henley, D. Holtzman, A. Lake, A.M. Noone, Annual Report to the Nation on the Status of Cancer, 1975-2012, featuring the increasing incidence of liver cancer, Cancer 122 (9) (2016) 1312–1337. [14] R.L. Siegel, K.D. Miller, A. Jemal, Cancer statistics, 2016, CA: Cancer J. Clin. 66 (1) (2016) 7–30. [15] D. Hashim, P. Boffetta, C. La Vecchia, M. Rota, P. Bertuccio, M. Malvezzi, E. Negri, The global decrease in cancer mortality: trends and disparities, Ann. Oncol. 27 (5) (2016) 926–933. [16] C. Bosetti, F. Levi, P. Boffetta, F. Lucchini, E. Negri, C. La Vecchia, Trends in mortality from hepatocellular carcinoma in Europe 1980–2004, Hepatology 48 (1) (2008) 137–145. [17] About national cancer registry programme. http://www.ncrpindia.org/ About_NCRP.aspx, 2016 (Accessed 01 September 2016). [18] National cancer registry programme: Three-year report of population based cancer registries 2012–2014. http://ncrpindia.org/Annual_Reports.aspx, 2016 (Accessed 01 September 2016). [19] F. Pons, M. Varela, J.M. Llovet, Staging systems in hepatocellular carcinoma, HPB: Off. J. Int. Hepato Pancreato Biliary Assoc. 7 (1) (2005) 35–41. [20] J.M. Llovet, A. Burroughs, J. Bruix, Hepatocellular carcinoma, Lancet 362 (9399) (2003) 1907–1917. [21] V. Mazzaferro, E. Regalia, R. Doci, S. Andreola, A. Pulvirenti, F. Bozzetti, F. Montalto, M. Ammatuna, A. Morabito, L. Gennari, Liver transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis, N. Engl. J. Med. 334 (11) (1996) 693–699. [22] J. Bruix, J.M. Llovet, Prognostic prediction and treatment strategy in hepatocellular carcinoma, Hepatology 35 (3) (2002) 519–524. [23] A. Raza, G.K. Sood, Hepatocellular carcinoma review: current treatment, and evidence-based medicine, World J. Gastroenterol.: WJG 20 (15) (2014) 4115– 4127.
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Review
“Hepatocellular carcinoma: A life-threatening disease” Shinu Chacko* , Subir Samanta Division of Pharmaceutical Chemistry, Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
A R T I C L E I N F O
Article history: Received 11 September 2016 Received in revised form 13 October 2016 Accepted 26 October 2016 Keywords: Hepatocellular carcinoma Transarterial chemoembolization Molecular targeted therapy Personalized medicine Immunotherapy Peptide hybrid
A B S T R A C T
An estimated rise in liver cancer incidence will increase to 95374 new cases by 2020. Hepatocellular Carcinoma (HCC), the most common primary malignant tumour of the liver, is considered to be the third leading cause of all cancer-related deaths and fifth common cancer worldwide. The reported data shows that the rate of HCC incidence in male population is three to four times higher compared with the female population. In the United States, HCV-induced liver cancer is increasing very fast because of the lack of proper treatment option. There are various treatment strategies available for HCC like liver transplantation, resection, ablation, embolization and chemotherapy still the prognosis is destitute. If the patient is eligible, liver transplantation is the only therapeutic option that may give around 90% survival rate, but the scarcity of liver donor limits its broad applicability. A sudden address is necessary to develop specific drugs, personalized medicine, for HCC. ã 2016 Elsevier Masson SAS. All rights reserved.
Contents 1. 2.
3.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hepatocellular carcinoma (HCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Risk factors and mechanism of hepatocarcinogenesis . . . . . . . . . . . . . . . . . . 2.1. Epidemiology of HCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. Treatment strategies for HCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3. Surgical resection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4. Liver transplantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5. Percutaneous ablation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6. Transarterial embolization (TAE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7. Immunotherapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8. Molecular targeted chemotherapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9. Checkpoint 1 and VEGFR: promising targets for anti-HCC drug development 2.10. Anti-cancer potential of small peptides and its hybrids . . . . . . . . . . . . . . . . . 2.11. Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1. Introduction Abbreviations: ADME, absorption distribution metabolism and excretion; AFP, alpha-fetoprotein; BCLC, Barcelona Clinic Liver Cancer; Chk 1, check point 1; HBV, Hepatitis B Virus; HCC, hepatocellular carcinoma; HCV, Hepatitis C Virus; LT, liver transplatation; NAFLD, nonalcoholic fatty liver disease; PDGF, platelet-derived growth factor; PS, performance status; TACE, transarterial chemoembolization; TSC, thiosemicarbazide; VEGFR, vascular endothelial growth factor receptors. * Corresponding author. E-mail address: [email protected] (S. Chacko).
Cancer develops when normal cells become abnormal, and the abnormal cells keep dividing and forms a lumps (tumours). All tumours are not cancerous, cancerous tumours (malignant) can grow into nearby tissues and may spread through blood or lymphatic system from the site where it originated (primary
http://dx.doi.org/10.1016/j.biopha.2016.10.078 0753-3322/ã 2016 Elsevier Masson SAS. All rights reserved.
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Fig. 1. Internal Anatomy of the liver.
cancer) to the other parts of the body and developed new cancerous tissue (secondary cancer or metastasis). The liver is the largest, lobed, glandular organ in the body. The internal anatomy of the liver is depicted in Fig. 1. The parenchymal tissue of the liver mainly consists of hepatocytes. Liver aids in digestion by producing biochemicals, store energy, protein synthesis and detoxification. The liver is getting perfusion at the rate of 85 mL/min/100 g of tissue which is 24% of total cardiac output. Most of the drugs are metabolized primarily in the liver with the help of enzymes and bile produced by the liver. Any diseases or injury to the liver may lead to impairment of these process and lead to the accumulation of toxic compounds in the body [1]. The primary liver cancer originates in the liver and its occurrence is increasing rapidly in every year. Worldwide, liver cancer is the sixth most common cancer (782451 new cases), the 2nd cause of cancer-related death (745,533 cases), and accounts for 5.6% of all cancers as per the data published in Globocan 2012
(Fig. 2). In 2020, it is estimated that liver cancer incidence will be rise to 95374 new cases [2] (Fig. 3). Among the various types of primary liver cancers like hepatocellular carcinoma (HCC), cholangiocarcinoma, angiosarcoma, hepatoblastoma, fibrosarcoma, leiomyosarcoma and rhabdomyosarcoma, HCC occupies major portion. 2. Hepatocellular carcinoma (HCC) Hepatocellular Carcinoma (HCC), also called malignant hepatoma, is a primary malignant tumour of the liver arising from the liver cells (hepatocytes). HCC is considered to be the third leading cause of all cancer-related deaths and fifth common cancer worldwide [3]. It accounts for around 80–90% of all liver cancers. Globally, the occurrence of HCC is increasing by 3–9% annually [4] and approximately 7.5 Lakhs of new cases of HCC occurs per year [5]. More than half a million people are diagnosed with HCC worldwide, including about 20,000 new cases in the United States,
Fig. 2. Estimated number of cancer incidence worldwide, all ages both sexes. Source: http://globocan.iarc.fr/old/pie_pop.asp?selection=224900&title=World&sex=0&type=0&window=1&join=1&submit=%C2%A0Execute accessed on 31-08-2016
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Fig. 3. Predicted liver cancer incidence worldwide all ages in 2020. Source: http://globocan.iarc.fr/old/burden.asp?selection_pop=224900&Textp=World&selection_cancer=14070&Textc=Liver&pYear=8&type=0&window=1&submit=%C2% A0Execute accessed on 31-08-2016
in each year. The male population are more prone to the liver cancer than female population [6]. 2.1. Risk factors and mechanism of hepatocarcinogenesis Nearly all HCC occurs in the presence of cirrhosis or advanced fibrosis. Thus, any cause of liver disease that can result in cirrhosis should be considered a potential risk factor for HCC. The distribution of risk factors in patients with HCC depends on the ethnic group, race or geographical region. The various common risk factors are;
Infection with Hepatitis B virus (HBV) or Hepatitis C virus (HCV) Alcoholic liver diseases Non-alcoholic fatty liver Aflatoxins
In Africa and East Asian countries including Taiwan, China, and Korea, HBV is the primary cause, whereas, in the West and Japan, HCV is the main risk factor, together with other causes of cirrhosis and alcoholism. The appropriate proportions of causes of HCC in the USA is tabulated in Table 1. Most of the risk factors favour development and progression of cirrhosis which is present in maximum cases of HCC [7]. Worldwide, infection with HBV is the primary reason for HCC in half of the patients, and it can cause HCC without cirrhosis. The factors which increase the risk of developing HCC in persons with HCV infection are sex, olde age, co-infection with human immunodeficiency virus (HIV) or HCB, diabetes or obesity.
Continued chronic use of alcohol (40–60 g of alcohol daily) is also a well-defined risk factor for HCC through the development of cirrhosis. Persons co-infected with HCV is more prone to HCC in combination with the heavy use of alcohol than in HCB coinfection [8]. Nonalcoholic fatty liver disease (NAFLD), which is present commonly in up to 90% of all obese persons and up to 70% of individuals with type 2 diabetes, has been proposed as a possible risk factor for hepatocellular carcinoma [9]. NAFLD is a group of conditions including mild hepatic steatosis and non-alcoholic steatohepatitis. In these circumstances, fat builds up in the liver. The fat causes inflammation and damage, which may lead to cirrhosis. Generally, all the risk factors transform healthy liver to HCC liver through fibrosis and cirrhosis (Fig. 4). The understanding of the mechanism involved in hepatocarcinogenesis (Fig. 5) is crucial for the development of new treatment. Hepatocarcinogenesis is a highly complex multistep process, and no single dominant or pathognomonic molecular mechanism exists in HCC. It starts from hepatic stem cells or mature hepatocytes under the condition of chronic liver disease initiated by oxidative stress, chronic inflammation and cell death followed by unrestricted proliferation/restricted regeneration and permanent liver remodelling. The chronic liver injury caused by HBV and HCV infection, chronic consumption of alcohol, nonalcoholic steatohepatitis and fatty liver, hereditary hemochromatosis, and primary biliary cirrhosis causes permanent hepatocyte damage. In response to cytokine stimulation caused by hepatocyte injury, an enormous compensatory cell proliferation and regeneration takes place followed by fibrosis and cirrhosis, particularly driven by the
Table 1 Approximate proportions of causes of hepatocellular carcinoma in the USA. Causes A) Chronic viral infections Hepatitis C Hepatitis B Hepatitis C + alcohol Both B) Other causes of cirrhosis Alcohol Cryptogenic Others (hemochromatosis, alpha-1 antitrypsin deficiency, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis, and nonalcoholic steatohepatitis) No cirrhosis or virus
Percentage 47–55 15–17 27 or above 2–5 9 7 6
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Fig. 4. Process involved in the transformation of healthy liver into Hepatocellular Carcinoma (HCC). Adapted from S. Chacko and S. Samanta, Computer Aided Drug Design [10].
synthesis of extracellular matrix components from hepatic stellate cells. Finally, in this carcinogenic environment hyperplastic and dysplastic nodules forms and normal liver tissue transforms to the cancerous. The molecular pathogenesis of HCC involves different genetic/epigenetic aberrations and alterations in multiple signalling pathways leading to the known heterogeneity of the disease concerning its biologic and clinical behaviour [12]. 2.2. Epidemiology of HCC Liver cancer incidence and death rates are increasing in many parts of the world, including North America, Latin America, and Central Europe. Liver cancer incidence rates were increased by 3.1% every year from 2008 to 2012 according to National Cancer Institute Surveillance, Epidemiology and End Results (SEER) Database of the National Cancer Institute in the US [13]. The incidence was three time's higher in men compared with women (11.5 versus 3.9 per 100,000). The rise in liver cancer incidence rate among non-Hispanic whites, non-Hispanic blacks, and American Indian/Alaska Natives, and a decline in non-Hispanic Asians and Pacific Islanders during this period may be related to the increasingly widespread vaccination of children against hepatitis B viral infection, the dominant HCC-related virus among Asian/
Pacific Islanders. In contrast to the falling death rates seen for all other common cancers like lung, breast, and prostate cancers, mortality from liver cancer in men increased by 2.8% every year [14], and for women, it rose by 3.4% annually [13,15,16]. In India, information on HCC is not sufficient, and data provided by the cancer registries are not accurate because of the poor reporting and diagnosing system and the patients who are diagnosed and treated for HCC by the speciality like Gastroenterology/Hepatology/Transplant Surgery/G.I. Surgery are not listed in the registries [5]. National cancer registry program (NCRP) was established in 1981 by Indian council of medical research (ICMR) to analyse and evaluate various cancer incidence in India statistically. Initially, three hospital-based cancer registries (HBCRs) and three population-based cancer registries (PBCRs) were established. By now, 27 PBCRs and more than 30 HBCRs have been established. The latest published registry data by ICMR was available in the cancer registry website (ncrpindia.org) from March 2016, which provides information on various cancers from 2012 to 2014 [17]. As per the latest NCRP data based on male population (Table 2), out of 27 PBCRs, 19 centres reported liver cancer in the first ten ranking and among 19, Sikkim, Naharlagun and Pasighat have reported liver cancer in the second position. In comparison with previous data published (2009–2011), incidence and mortality of
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Fig. 5. The suspected mechanisms of hepatocarcinogenesis for the various risk factors Adapted from P.A. Farazi et al. Cancer [11].
liver cancer have increased gradually, and the overall impact is higher in male population [18].
Radiation Targeted therapy Chemotherapy
2.3. Treatment strategies for HCC The treatment of liver cancer depends on many factors like the stage (extent) of cancer and how well the liver is working, age, the general state of health, and personal preferences. The Barcelona Clinic Liver Cancer (BCLC) classification (Fig. 6), widely accepted HCC staging system, links HCC with the patient’s performance status (PS) and cancer-related symptoms. This staging system differentiates early stage cancer with an advanced stage so as to diagnose HCC in the early stage and to select proper treatment option [19]. The treatment strategies are broadly divided into curative and palliative treatment. Curative treatments are applied to the HCC patients who are in very early or early stages, and palliative care provided to the patients in advanced stage HCC. Based on the different stages, treatment options may include: Curative treatments
2.4. Surgical resection It is the treatment choice, especially in Asian countries [6], for patients with HCC in the very early stage and without cirrhosis. In the case of Cirrhotic patients selection should be done by tumour size, liver function, portal hypertension and total bilirubin level for their eligibility for resection. Such HCC patients having single tumour of size less than 3 cm, well-preserved liver function, normal portal hypertension (a hepatic venous pressure gradient greater than 10 mm of Hg) moreover, normal total bilirubin level (1 mg per deciliter) achieves good results after resection even in cirrhotic condition, and they may have a survival rate of 70% in five years. The biggest problem with resection is the chances of getting liver failure, so strict selection should be made [20]. 2.5. Liver transplantation
Surgery (Resection or liver transplant) Other local treatments, such as ablation or embolization Palliative treatments
In unresectable HCC associated with cirrhosis, liver transplantation (LT) is the best curative treatment [21] with high survival rate and lowest recurrence chance. The main advantage of LT is that
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Table 2 Population-based cancer registry of liver cancer in male population during 2012-14 in India [18]. ‘X’ indicates not in first ten positions. PBCRs
Total Population (Male)
Total cancer
Liver cancer in male
Liver cancer in female
Bangalore Barshi Rural Barshi expanded Bhopal Chennai Delhi Mumbai Cachar Dibrugarh Kamrup Manipur Mizoram Sikkim Ahmedabad Aurangabad Kolkata Kollam Nagpur Pune Trivandrum Meghalaya Tripura Nagaland Wardha Naharlagun Pasighat Patiala
8,885,498 (4,616,478) 1,518,132 (7,98,979) 43,28,959 (22,579,96) 4,019,413 (2,088,045) 9,409,435 (4,715,650) 16,896,984 (9,012,555) 12,506,206 (6,728,832) 5,438,912 (2,076,093) 4,085,263 (2,076,093) 4,082,409 (2,141,950) 9,139,837 (4,600,029) 3,458,396 (1,741,869) 1,884,412 (9952,02) 1,19,03,496 (62,639,52) 38,31,611 (19,80,880) 44,87,332 (23,38,295) 79,42,156 (37,39,048) 51,52,611 (26,20,014) 1,04,33,334 (54,77,270) 99,52,077 (47,53,308) 59,33,041 (29,64,519) 1,13,84,169 (57,99,657) 21,08,595 (10,91,662) 39,486,14 (20,26,323) 24,59,625 (12,56,000) 4,14,016 (2,10,521) 5930509 (3130053)
12624 4308 2032 39757 15258 26333 33230 2539 2521 3256 3969 3380 1155 11844 1888 9038 9030 5422 8594 5755 4248 2612 6330 1361 2730 334 6011
4.3% (7th common) 6.2%*(3rd common) 4.3% (5th common) X 3.9% (7th common) X 5.7% (4th common) X 3.7% (9th common) 3.3% (10th common) 4.1% (7th common) 5.5% (4th common) 7.6% (2ndcommon) X X 3.0% (10th common) 4.7% (4th common) 2.8% (10thcommon) 4.5% (7th common) 4.0% (7thcommon) 2.2% (9th common) 2.6% (10thcommon) 2.9% (9th common) 6.2 (4th common) 19.9% (2ndcommon) 7.4% (2nd common) 3.1% (10th common)
X (not in first 10) X X X X X 2.8% (8th common) X X X X 3.9% (6th common) 5.8% (7thcommon) X X X X X X X X X X 2.3% (9th common) 6.8% (5th common) 3.8% (5th common) X
it not only removes the tumour but also the underlying cirrhosis. The limitation is the availability of compatible liver in the stipulated period, so selection on the basis of predicted success rate play a significant role in determining LT. Living donor LT (LDLT) [22] may be considered as the better alternative for cadaveric LT to increase the availability and to reduce waiting period. Those
candidates following Milan criteria for LT (one nodule less than 5 cm or not more than three nodules of less than 3 cm) achieve 75% overall survival in 5 years and less than 15% tumour recurrence rate [6,23]. A considerable amount of patients is dropping out from the waiting list for LT due to the unavailability of healthy liver for a long
Fig. 6. BCLC staging classification and treatment schedule for HCC. N: nodule; M: Metastasis; PS: Performance status; TACE: Transarterial chemoembolization; BSC: Best supportive care. Adapted from Llovet J. M. et al., Lancet 2003 [20].
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time. By that time candidates complying Milan criteria for LT are becoming disqualified due to tumour progression. So treatment with other options is necessary for those candidates during waiting period to satisfy Milan criteria throughout the waiting period [23]. 2.6. Percutaneous ablation Percutaneous ablation is a choice of treatment for BCLC stage 0 and A unresectable HCC patients and considered as the first line therapy in some parts of Japan [24]. In this technique, inoperable neoplastic cells are destroyed by chemicals like alcohol and acetic acid, or by altering temperature at the tumour site using radiofrequency (RF), laser, or cryoablation. Radiofrequency ablation (RFA) is minimally invasive, can repeatedly be used and have fewer side effects. Applicability of this technique is limited to early stage HCC of less than 2 cm, and it achieves around 40–70% survival rate in 5 years. In RFA a small bipolar or unipolar needle is inserted into the liver and correctly placed into the tumour. RF energy is delivered to the tumour by using RF generator, and tumour cells are destroyed with the help of frictional heat produced by rapid agitation [25]. Reports showed that it is more effective than percutaneous ethanol injection (PEI) and requires fewer treatment sessions [26], but for tumours of less than 2 cm ethanol ablation may produce 90–100 percent response. The main disadvantage of these local therapies are the high rate of recurrence and can only apply to the early stage HCC. However, the fact is that most of the HCC diagnosed are in later stage [12]. 2.7. Transarterial embolization (TAE) TAE is widely accepted palliative treatment option for those who are in the intermediate stage of hepatic carcinoma. In this technique, an embolus, usually gelatin mixed with lipiodol (a radio-opaque contrast agent), is inserted into the blood vessel using a catheter to block the blood supply to the tumour cells. As a principle blockage of hepatic artery results in extensive necrosis of the HCC which are widely vascularized [27]. Sometimes embolus may be included with tumour attacking agents like chemicals
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(transarterial chemoembolization (TACE), radiation or radiopharmaceuticals (radioembolization) to destroy the cancer cells. Doxorubicin, mitomycin, and cisplatin are used as anticancer agents in embolization method. TACE is a standard care treatment for HCC patients with preserved liver function, asymptomatic multinodular tumours without vascular invasion or extrahepatic spread. It may give 40– 50% 5-year survival rate and achieve 15–62 percent partial response [28]. By the application of TACE, tumour progression may be delayed [22], and this is especially useful for patients who are waiting for LT. The drawback of this technique is the high chances recurrence (around 70% in 5 years) [12]. The intermediate stage HCC patients are heterogeneous and have a different degree of tumour burden, so selective TACE is needed. In this regard, selection of anti-tumour agents, embolizing agent, and radioopaque agents is crucial to the success of this method. The recent advancement in TACE, use of microspheres (drug-eluting beads), overcomes some of the drawbacks mentioned above. Microspheres have the ability to release the incorporated drug, doxorubicin, in a controlled fashion so as to localise drug concentration and to control the amount of drug that reaches systemic circulation [29]. TACE with a drug-eluting bead (DEB-TACE) is a better replacement for conventional lipiodol (ethiodized oil) based TACE. Radioembolization is embolization with radiation. Microspheres or resin beads with radioactive isotope yttrium Y-90 [30] is delivered to the blood vessels that feed the tumour. The size of the beads is around 35 mm but in the case of TACE it is 100– 500 mm, and it causes ischaemia also. Some studies showed that radioembolization is superior to TACE concerning side effect, response rate and time to progression [31] but the cost of the treatment limit its broad accessibility. It also been reported that this is safer in the advanced stage of HCC [32]. 2.8. Immunotherapy Immunotherapy utilizes the innate immune system to recognize the cancer cells and to kill them. HCC is an immunocompromised condition, many of the immunocytes are found to be
Table 3 Trials with active recruitment of molecular-targeted therapies in hepatocellular carcinoma. Adapted from [39]. Drugs
Trial phases
Number of trials
Molecular targets
Sorafenib Bevacizumab Erlotinib Everolimus Brivanib Sunitinib Rapamycin AZD6244 Bortezomib TAC-101 Cediranib Cetuximab Cixutumumab Temsirolimus Linifanib PI-88 ARQ197 BIBF1120 Dasatinib GC33 Gefitinib Lapatinib Licartin Pazopanib Alvocidib
1, 1–2, 2, 3, 4 1, 1–2, 2 1, 1–2, 2, 3 1, 1–2, 2, 3 1, 2, 3 2, 3 1, 2–3, 3 1–2, 2 1, 2 1–2, 2 1, 2 1, 2 1, 2 1, 2 2, 3 2, 3 1, 2 2 2 1 2 2 2, 4 2 1, 2
128 19 15 22 6 10 22 3 3 4 2 2 3 22 2 2 4 2 2 2 2 2 2 4 1
BRAF, VEGFR, PDGFR VEGF EGFR MTORC1 FGFR, VEGFR, PDGFR VEGFR, PDGFR, KIT MTORC1 MEK Proteasome RAR-a VEGFR EGFR IGF-1R MTORC1 VEGF, PDGFR Endo-D-glucuronidase heparinase MET VEGFR, PDGFR, FGFR BCR-ABL GPC3 EGFR EGFR, HER2/neu HAb18G/CD147 VEGFR, PDGFR, KIT Cyclin-dependent kinase
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deficient. Both HBV and HCV infection negatively affects the innate and adaptive mechanism of the immune system in the body [33]. So by the application of immunotherapy, the immune system of the body can be activated and which improves patient's outcome. It produces nontoxic, systemic and long-term anti-cancer activity. Immunotherapy can be differentiated into the following: Immunomodulators and tumour vaccines: In an indirect way these are used to recover the immune response to HCC. Adoptive immunotherapy: In this active immune cells are delivered to destroy cancer cells. As discussed earlier, the main trigger factors for HCC are HBV and HCV. To a large extent the introduction of HBV vaccine eradicate its occurrence and decreases HBV-induced HCC. The research for HCV vaccine is still going on. At the same time, research on the anti-HCC vaccine is also going on. The main limitation for the development of tumour vaccine is the unavailability of tumour specific antigens or tumour-associated antigens (TAA) [34]. Peptide-based anti-HCC vaccines using TAAs like alpha-fetoprotein (AFP) and glypican3 (GPC3) are in clinical trials. An overexpression of GPC3 found in around 80% of HCC and AFP is considered as a useful biomarker of 70–80% of HCC. Many clinical studies targeting these molecules and other biomarkers [35,36] are in different phases and may give suitable candidates for immunotherapy. Adoptive immunotherapy utilizes tumour specific T cells which are grown outside the body and have the ability to kill cancer cells.. The advantages of this method are 1) Specificity: recognize cancer cells from the healthy cell; 2) Ability of T cells for clonal expansion after activation; 3) Able to give effect in metastasis, and 4) Longer days of therapeutic effect due to the T cell’s memory. However, the cost-effectiveness is still a problem and depends on the availability and source of T cells [37]. 2.9. Molecular targeted chemotherapy HCC is heterogeneous in nature both phenotypically and genetically. Each and every patient shows a different kind of tumour characteristics. So single treatment strategy cannot apply to everyone. The understanding of molecular pathogenesis of HCC paves a way to the personalized medicine. Targeting a particular receptor upregulated in HCC helps to reduce the side effects by blocking its action in another receptor. Molecular targeted signalling pathways like mitogen-activated protein kinases (MAPK) pathway (Ras/Raf/MEK/ERK pathway), the Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3k), mammalian target of rapamycin [mTOR] pathway and the canonical Wnt pathway (Wnt/beta-catenin pathway) have been recognized as significant for HCC cell proliferation and angiogenesis. Growth and angiogenic factors/receptors like vascular endothelial growth factor [VEGF], platelet-derived growth factor [PDGF] and particularly epidermal growth factor [EGF] receptor are also overexpressed in HCC. The era of molecular targeted therapy in HCC was started after the success of sorafenib, a multikinase inhibitor, till then there was no single drug available for the first-line treatment of advanced HCC. In November 2007 sorafenib got FDA approval on the basis SHARP trial which compared the efficacy of sorafenib with placebo in advanced HCC. The results showed improvement in median survival and time to progression in comparison with placebo [38]. Orally active sorafenib targets MAPK pathway in HCC and produce anti-angiogenic activity through tyrosine kinases like VEGFR and PDGFR [39]. After the emergence of sorafenib, research in the area of targeted therapy increased. Currently, around 50 agents which aim various targets are in different phases of clinical trial (Table 3).
HCC is a highly vascularized tumour. The drugs which target receptors like VEGF and PDGF may block angiogenesis and proliferation. Bevacizumab, brivanib and ramucirumab are having the anti-angiogenic effect and are under clinical trial. Sorafenib has also shown good effect along with TACE and radio-embolisation. Hypoxic condition generated due to the embolization leads to the expression of VEGF and neovascularization of surviving tumour cells. Sorafenib blocks neovascularization and provides benefits in the treatment [40]. Gadani et al. showed improved overall survival of patients after the use of yttrium-90 treatment along with sorafenib [41]. 2.10. Checkpoint 1 and VEGFR: promising targets for anti-HCC drug development Checkpoint kinase1 (Chk1) [42] (a serine-threonine kinase) and VEGFR-2 [43,44] (a tyrosine kinase) have been identified as the critical targets in the development of an anti-cancer drug against HCC. Yin Xie and co-workers found that the average of Chk1 mRNA level in the liver tumour was 4.14 times higher than the corresponding non-tumour liver tissues [45]. Chk1 protein contains 476 amino acids and gets activated with Deoxyribonucleic Acid (DNA) damage response [42]. It mainly helps damaged DNA to repair at G2 and S phase of cell cycle along with tumour suppressor gene p53. In tumour cells, repairing of damaged DNA through tumour suppressor gene p53 (like in the normal cell) is mutated and purely depends on Chk 1 mediated DNA repair. Inhibition of Chk 1 kinase blocks the total repairing mechanism of damaged DNA in the cancer cell and leads to mitotic cataphoresis and cell death without affecting the normal cell which will repair with the help of p53 gene [46]. VEGFR-2 is also a novel target for the development of anticancer drugs since it is involved in cancer cell proliferation, apoptosis, angiogenesis, invasion and metastasis and is overexpressed in HCC. Inhibition of VEGFR-2 receptor prevents tumour growth through anti-angiogenic effect. Generally, solid tumours are associated with the excess formation of vascular network (angiogenesis) to acquire nutrition necessary for growth and metastasis [47] and which is very fast in HCC [44]. A molecule having both Chk1 and VEGFR-2 inhibitory (multi-targeted) properties may, therefore, be a promising drug candidate for the treatment of HCC without affecting the functions of normal cells. 2.11. Anti-cancer potential of small peptides and its hybrids The evolution of multidrug resistance substantially lowers the success rate of anti-cancer therapy with chemotherapeutic agents. [48]. Investigation for novel strategy is thereby necessary to boost the success rate by limiting drug resistance. Nowadays, the field of anti-cancer drug development is mainly focused on designing of the molecules having target specificity, lesser toxic effects and better differentiation between the tumour cell and normal cell. Most of the currently available anti-cancer drugs do not
Fig. 7. 2D structure of thiosemicarbazide (A) and semicarbazone (B) drawn by Chem. Draw 10.0.
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preferentially accumulate at the tumour site owing to low specificity thereby leading to the incomplete response, increased toxicity and development of drug resistance. Peptides are known to be highly specific to individual protein targets, amenable to site-specific modification and highly selective. However, its low tissue permeability and high susceptibility towards proteolysis limit usage as an oral drug. Amino acids and peptides are taxonomically natural, physiologically nontoxic and chemically multifunctional. Rationalized conjugates of biologically active synthetic agents with amino acids or peptides are hypothesized to be more potent and particularly lesser toxic than their parent biological. Preparing hybrids of an amino acid or peptide with biologically active compounds like thiosemicarbazide (TSC) or semicarbazones tends to stabilize the peptide bond and results in molecules with target specificity [49] and lesser toxicity [50]. TSC and semicarbazones (Fig. 7) are derivatives of thiourea and urea, respectively, wherein one amino group is replaced with hydrazine. They are known to have antiviral [51] and anti-cancer [52,53] activity which usually mediates through binding to Cu and Fe ions in the cells. Thiosemicarbazones being the inhibitors of ribonucleotide reductase arrests the cell cycle at G1/S phase and then inactivates the ribonucleic acid (RNA) synthesis. 3. Concluding remarks Hepatocellular carcinoma is a heterogeneous solid tumour affecting the main detoxifying organ in our body. Chronic liver disease caused by the infection of HCV and HCB is the primary causative agent for HCC. The heterogeneity of the disease makes treatment selection tough. BCLC system of HCC classification helps the physician to check the eligibility of the patients for any available therapies. If the patient is eligible, LT is the best option for the treatment, and it may give success rate of about 90% since LT not only removes cancer but also the underlying liver disease. It is necessary to diagnose the disease in the early stage to treat it efficiently. In the case of HCC till date no diagnostic tool has been developed to detect cancer in the early stage. If this happens, ablation and embolization give better outcome and longer survival rate. All the other treatment option have a high rate of recurrence. Till 2007 there was no first line drug for the advanced stage of HCC. The discovery of sorafenib opens an excellent way to the research on multikinase inhibitors and it still continues. Immunotherapy, another pillar of HCC treatment, improves the natural immunity of the body to fight against HCC. However, it also needs a lot of clinical trials to establish as a promising treatment for HCC. Overall, the available treatment options are insufficient to treat HCC in a systematic way to result in high patient compliance and less chance of recurrence. Now the research is going in a direction to find specific targets, targeted therapy, for HCC through the vast knowledge of molecular mechanism and signalling pathway. Hybrids of peptides with different heterocyclics are the better lead to target HCC cells since peptides are natural molecules and having target specificity and less chance of toxicity. Target specificity is an important aspect to be considered in the development of anti-cancer drugs because it may discard the chance of drug resistance, the main drawback of existing anti-cancer drugs. The Absorption, distribution, metabolism, elimination and toxicity (ADMET) profile can also be improved using peptide hybrids. Consideration of ADMET in the early phase of drug development will reduce the chance of synthesising low bioavailable drugs. Discovery of such target specific molecules for any subgroup of patients will result in the development of personalized medicine.
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Conflict of interest The authors confirm that this article content has no conflict of interest. Acknowledgment The authors are grateful to the University Grants Commission, New Delhi, India, for providing Basic Scientific Research (BSR) fellowship assistance [7-32/2007(BSR)] for the successful completion of this work and also thankful to the Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Jharkhand, India, for giving lab facilities. References [1] C.R. Craig, R.E. Stitzel, Modern Pharmacology with Clinical Applications, 5th ed., Lippincott Williams & Wilkins, 2004. [2] Globocan, Estimated Cancer Incidence, Mortality and Prevalence Worldwide in 2012, Globocan, 2012.
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