Paul J Ross
email: paul.ross@gstt.nhs.uk

Abid Rosemary Lord

Paul ; Ross

St Guy's

Thomas'

A Suddle

P J Ross

Dr Paul Ross

Emerging strategies in the treatment of advanced hepatocellular carcinoma: the role of targeted therapies

Emerging strategies in the treatment of advanced hepatocellular carcinoma: the role of targeted therapies.

Introduction

Hepatocellular carcinoma is the fifth most common malignancy worldwide, with approximately 500,000 new cases per year and more than 600,00 deaths annually [START_REF] Llovet | Hepatocellular carcinoma[END_REF]. Approximately 80% of cases arise in Asia and Africa mainly due to chronic hepatitis B virus (HBV) infection. The incidence of HCC is rising in the United States and Europe because of the increased incidence if hepatitis C (HCV) infection [START_REF] El-Serag | Rising incidence of hepatocellular carcinoma in the United States[END_REF]. China has the highest mortality rate for both men and women reflecting the prevalence of HBV infection [START_REF] Jemal | Cancer statistics[END_REF]. HCC is now the leading cause of death in Europe in patients with cirrhosis [START_REF] Fattovich | Morbidity and mortality in compensated cirrhosis type C: a retrospective follow-up study of 384 patients[END_REF]. As such HCC is a major cause of morbidity and mortality worldwide.

Treatment Options

Surgical and loco-regional Five year relative survival rates are less than 10% [START_REF] Jemal | Cancer statistics[END_REF]. The only curative treatments for HCC are surgical resection and liver transplantation but only benefit approximately 25% [START_REF] Llovet | Hepatocellular carcinoma[END_REF]. Surgical resection is only suitable for patients with well preserved liver function and no portal hypertension. Five-year survival following resection is 15-39% [START_REF] Takenaka | Results of 280 liver resections for hepatocellular carcinoma[END_REF]. In well selected patients, the 5 year survival rates have approached 50% in a number of large series [START_REF] Llovet | Systematic review of randomized trials for unresectable hepatocellular carcinoma: Chemoembolization improves survival[END_REF]. Liver transplantation has become the preferred treatment for early stage HCC in cirrhotic patients with 5-year survival rates of 70-80% and tumour recurrence rates of only 10% [START_REF] Llovet | Intention-to-treat analysis of surgical treatment for early hepatocellular carcinoma: resection versus transplantation[END_REF][START_REF] Mazzaferro | Liver transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis[END_REF][START_REF] Bismuth | Liver transplantation for hepatocellular carcinoma[END_REF].

Treatment options for unresectable disease include locoregional therapy [START_REF] Llovet | Arterial embolisation or chemoembolisation versus symptomatic treatment in patients with unresectable hepatocellular carcinoma: a randomised controlled trial[END_REF][START_REF] Lo | Randomized controlled trial of transarterial lipiodol chemoembolization for unresectable hepatocellular carcinoma[END_REF] and systemic therapies [START_REF] Leung | Systemic therapy for hepatocellular carcinoma[END_REF]. Thus far transarterial embolisation (TACE) has been the only locoregional therapy to demonstrate a survival advantage and it is the treatment of choice for intermediate stage HCC (tumour greater than 4cm or multiple lesions in the liver) [START_REF] Llovet | Systematic review of randomized trials for unresectable hepatocellular carcinoma: Chemoembolization improves survival[END_REF][START_REF] Llovet | Arterial embolisation or chemoembolisation versus symptomatic treatment in patients with unresectable hepatocellular carcinoma: a randomised controlled trial[END_REF]. Based on this evidence TACE became the standard first-line non-curative therapy for non-surgical/multifocal HCC. Nonetheless, treatment is associated with toxicity and mortality. There is heterogeneity in practice in respect of the embolic particle, lipioidal use, and type of chemotherapy and frequency of administration. The chemotherapy used by a particular unit is often determined by which drug the physicians and radiologists have experience with and are comfortable using. Doses used are often extrapolated from previous experience and what is thought to be 'safe'. Treatment schedules have not necessarily taken into account the projected oncologic behaviour of the tumour.

Studies with TACE have been undertaken in patients with intermediate stage HCC with disease confined to the liver, no main portal vein involvement and good performance status. In contrast studies with systemic therapy, including sorafenib, have been undertaken in patients with advanced HCC not suitable for treatment with TACE. There is a clear rationale for evaluating the combination of TACE in combination with the novel targeted agent sorafenib to evaluate whether this may improve the outcome for patients with intermediate stage disease. TACE results in increased levels of vascular endothelial growth factor (VEGF), a key driver of angiogenesis increase. These increased levels are associated with increased rate of metastasis and shorter survival. In addition, the Raf/Mek/Erk pathway is important in the development of HCC. Sorafenib as discussed below is an inhibitor of both these pathways. The TACE-2 trial, co-ordinated by the National Cancer Research Network, is now underway to evaluate the addition of sorafenib to TACE.

Systemic Therapies

For patients presenting with disease not amenable to locoregional therapy many will require palliative care alone. However, patients with well preserved liver synthetic function may benefit from systemic chemotherapy. Response rates to single agent cytotoxic chemotherapy range between 0-20% with anthracyclines such as doxorubicin yielding the best response rates of up to 20% [START_REF] Nerenstone | Clinical trials in primary hepatocellular carcinoma: current status and future directions[END_REF] but with no definite survival benefit. Lai et al conducted a randomised trial of adriamycin versus no treatment in advanced HCC in 60 and 46 patients respectively [START_REF] Lai | Doxorubicin versus no antitumor therapy in inoperable hepatocellular carcinoma. A prospective randomized trial[END_REF]. The median survival rate was 10.6 versus 7.5 week s respectively (p=0.036) however a 25% fatal complication rate due to septicaemia and cardiotoxicity in the treated arm lead the authors to conclude that adriamycin could not be recommended as an ideal drug of choice for advanced HCC. Newer agent cytotoxics have not shown any better responses and have sometimes shown lesser activity.

Nolatrexed is a novel thymidylate synthase inhibitor and has demonstrated limited activity in advanced HCC [START_REF] Mok | A multi-centre randomized phase II study of nolatrexed versus doxorubicin in treatment of Chinese patients with advanced hepatocellular carcinoma[END_REF][START_REF] Stuart | A Phase II trial of nolatrexed dihydrochloride in patients with advanced hepatocellular carcinoma[END_REF]. A subsequent phase III trial compared the use of nolatrexed versus doxorubicin in unresectable HCC [START_REF] Gish | Phase III randomized controlled trial comparing the survival of patients with unresectable hepatocellular carcinoma treated with nolatrexed or doxorubicin[END_REF]. Median overall survival was 22.3 weeks for nolatrexed versus 32.3 weeks for Doxorubicin (p=0.0068) and the hazard ratio was 0.753 in favour of doxorubicin. This was the largest randomised controlled trial using doxorubicin as the control arm and whilst no benefit was demonstrated for the use of nolatrexed, the higher than expected survival rates in both treatment groups may relate to the advances in the management of HCC including better supportive therapies, such as growth factors and greater expertise in the treatment of patients with cirrhosis Combination chemotherapy with doxorubicin, cisplatin and 5-fuorouracil with or without interferon [START_REF] Leung | Complete pathological remission is possible with systemic combination chemotherapy for inoperable hepatocellular carcinoma[END_REF][START_REF] Yeo | A randomized phase III study of doxorubicin versus cisplatin/interferon alpha-2b/doxorubicin/fluorouracil (PIAF) combination chemotherapy for unresectable hepatocellular carcinoma[END_REF] have increased response rates modestly (13-39%) but with no clear impact on survival. Taieb et al examined the combination of gemcitabine and oxaliplatin (GEMOX) in advanced HCC and demonstrated a 19% clinical response rate and an acceptable toxicity profile [START_REF] Taieb | Gemcitabine plus oxaliplatin for patients with advanced hepatocellular carcinoma using two different schedules[END_REF] Most regimens have not been validated in randomised trials and therefore their clinical significance is uncertain. In addition combination regimens are often associated with greater toxicities when compared with single agent. In one of the few randomised studies undertaken Yeo et al compared doxorubicin with cisplatin/ interferon α-2b/ doxorubicin and 5-fluorouracil in unresectable HCC. Response rates were 10.5% versus 20.9% respectively with a nonstatistically significant median survival advantage of 6.83 versus 8.67 months (p= 0.83) [START_REF] Yeo | A randomized phase III study of doxorubicin versus cisplatin/interferon alpha-2b/doxorubicin/fluorouracil (PIAF) combination chemotherapy for unresectable hepatocellular carcinoma[END_REF].

However the combination regimen was associated with increased treatment related toxicity over the single agent regimen and therefore its clinical application is limited. In conclusion, although doxorubicin or doxorubicin-based combination therapies are widely used there is no regimen that can be clearly defined as the standard for treating advanced HCC.

These disappointing results can be partially explained by the fact that HCC cells are relatively well differentiated and carry several mechanisms of drug resistance. HCC cells usually contain high levels of dihydropyrimidine dehydrogenase that makes them resistant to 5-fluorouracil [START_REF] Jiang | Dihydropyrimidine dehydrogenase activity in hepatocellular carcinoma: implication in 5-fluorouracil-based chemotherapy[END_REF].

HCC cells also over-express the multidrug resistance gene(MDR1) [START_REF] Chenivesse | MDR1 (multidrug resistance) gene expression in human primary liver cancer and cirrhosis[END_REF] and the gene product Pglycoprotein [START_REF] Soini | Expression of P-glycoprotein in hepatocellular carcinoma: a potential marker of prognosis[END_REF]. This explains for example the total resistance to paclitaxel [START_REF] Chao | Phase II and pharmacokinetic study of paclitaxel therapy for unresectable hepatocellular carcinoma patients[END_REF], which is a Pglycoprotein substrate.

In addition, cirrhosis can have a profound impact on anticancer drug therapy. It not only decreases drug metabolising enzyme activity, but also alters the absorption, plasma protein binding, distribution, and renal excretion of drugs. Intra-hepatic shunts produced during cirrhosis allow drugs to be routed around hepatocytes, thus decreasing their first-pass extraction [START_REF] Elbekai | The effect of liver cirrhosis on the regulation and expression of drug metabolizing enzymes[END_REF].

However, all routes of hepatic metabolism are not equally impaired. As hepatic dysfunction progresses in cirrhotic patients, reduced synthesis of albumin occurs that leads to a decrease in plasma protein binding of drugs. For drugs that are more than 90% protein-bound this increase in the free drug fraction may be substantial and have serious clinical consequences. It is imperative that a liver cirrhosis score such as the Child-Pugh Classification system (Table 1) be obtained before therapy and monitored frequently thereafter. The synthetic function may be so significantly impaired in a patient with a Child's-Pugh C score, that for safety reasons they should not be treated.

These issues highlight the difficulties surrounding the use of systemic therapies in HCC and partly explain the disappointing results obtained with cytotoxic agents. Clearly there is a need for effective novel systemic therapies if an impact is to be made in the treatment of advanced HCC.

Novel Therapeutic Targets for the Treatment of HCC

HCC is notable for its highly aggressive behaviour, hypervascularity, portal and hepatic vein invasion, and early metastasis. Angiogenic factors such as vascular endothelial growth factor (VEGF), platelet-derived endothelial growth factor, and basic fibroblast growth factor released from the tumour itself, inflammatory cells and/or tumour stromal cells participate in the neovascularisaton of HCC [START_REF] Poon | Correlation of serum basic fibroblast growth factor levels with clinicopathologic features and postoperative recurrence in hepatocellular carcinoma[END_REF][START_REF] Miura | Increased expression of vascular endothelial growth factor in human hepatocellular carcinoma[END_REF][START_REF] Torimura | Increased expression of vascular endothelial growth factor is associated with tumor progression in hepatocellular carcinoma[END_REF]. Aberrant VEGF expression is a prominent clinical feature in HCC and may correlate with HCC tumour invasion and metastasis [START_REF] El-Assal | Clinical significance of microvessel density and vascular endothelial growth factor expression in hepatocellular carcinoma and surrounding liver: possible involvement of vascular endothelial growth factor in the angiogenesis of cirrhotic liver[END_REF] and may contribute to the development of the stroma in HCC [START_REF] Li | Serum vascular endothelial growth factor is a predictor of invasion and metastasis in hepatocellular carcinoma[END_REF].

The hypervascular nature of HCC has lead to the exploration of antiangiogenic agents as a treatment for advanced HCC. The first of these agents investigated was thalidomide, but poor tolerability limited treatment and no clinical benefit was demonstrated [START_REF] Schwartz | Thalidomide in advanced hepatocellular carcinoma with optional lowdose interferon-alpha2a upon progression[END_REF]. Median progression free survival was 2.1 months and median overall survival was 5.5 months consistent with limited efficiency. Toxicity was significant with fatigue and severe fatigue reported in 75% and 20% of patients respectively. High levels of VEGF have been associated with inferior survival in HCC [START_REF] Poon | Prognostic significance of serum vascular endothelial growth factor and endostatin in patients with hepatocellular carcinoma[END_REF][START_REF] Chao | Prognostic significance of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin in patients with resectable hepatocellular carcinoma after surgery[END_REF] and as a consequence bevacizumab, a humanised monoclonal antibody against VEGF has been investigated in the treatment of advanced HCC . In addition to its potential direct antiangiogenic effects, bevacizumab may enhance chemotherapy administration by "normalising" tumour vasculature and decreasing elevated interstitial pressure in tumours [START_REF] Willett | Direct evidence that the VEGF-specific antibody bevacizumab has antivascular effects in human rectal cancer[END_REF][START_REF] Jain | Normalizing tumor vasculature with anti-angiogenic therapy: a new paradigm for combination therapy[END_REF]. Bevacizumab has been investigated in a phase II study in combination with GEMOX [START_REF] Zhu | Phase II study of gemcitabine and oxaliplatin in combination with bevacizumab in patients with advanced hepatocellular carcinoma[END_REF]. The objective RR was 20% and 27% had stable disease. The median OS was 9.6 months and median progression free survival (PFS) was 5.3 months, with the 3 and 6 month PFS approaching 70% and 48% respectively. The regimen could be safely administered with close monitoring in the majority of patients.

The epidermal growth factor receptor/ human epidermal growth factor receptor 1 (EGFR/HER1) and its ligands EGF and transforming growth factor-alpha (TGF-α) are important in cell proliferation, as well as motility, adhesion, invasion, survival and angiogenesis [START_REF] Gibbs | Anticancer drug targets: growth factors and growth factor signaling[END_REF][START_REF] Woodburn | The epidermal growth factor receptor and its inhibition in cancer therapy[END_REF]. It has been suggested that hypomethylation of the EGF receptor gene may be associated with the development of HCC [START_REF] Kaneko | Hypomethylation of c-myc and epidermal growth factor receptor genes in human hepatocellular carcinoma and fetal liver[END_REF]. Studies have indicated that EGFR/HER1 is actively expressed in human hepatoma cells and that EGF may be one of the mitogens needed for the growth of hepatoma cell lines [START_REF] Xu | EGFR expression and EGF stimulation of proliferation in human liver carcinoma cells[END_REF]. Erlotinib is an orally active, potent, selective inhibitor of the EGFR/HER1-related tyrosine kinase enzyme. It inhibits EGF-dependent proliferation of cancer cells and blocks cell-cycle progression into the G1 phase. Its use in advanced HCC was investigated in a phase II study of thirty eight patients, 47% of whom had received prior chemotherapy [START_REF] Philip | Phase II study of Erlotinib (OSI-774) in patients with advanced hepatocellular cancer[END_REF]. 32% were progression free at six months, and three patients had partial radiologic responses of 2, 10 and 11 months duration. Disease control was seen in 59% and median overall survival time was 13 months. Toxicities were predominantly cutaneous and 24% of patients required dose reductions because of toxicity. Toxicities were greater in those with Child-Pugh classification B who were more likely to experience grade 3 or 4 toxicity than those with Child-Pugh A classification again highlighting the need for careful stratification of patients.

A phase II trial of bevacizumab and erlotinib in advanced HCC has recently been reported by Thomas et al [START_REF] Thomas | Phase II trial of the combination of bevacizumab and erlotinib in patients who have advanced hepatocellular carcinoma[END_REF]. 62.5% were progression free at 16 weeks which was the primary endpoint.

Ten patients achieved a partial response with an overall RR (intent to treat) of 25%. Median PFS was 39 weeks and median OS was 68 weeks. Gastrointestinal haemorrhage occurred in 12.5% of patients, one episode of which was fatal. Clearly haemorrhage is a concern in patients with cirrhosis who may have portal hypertension, varices or coagulopathy. This activity however is felt to be clinically meaningful to warrant further evaluation in randomised trials.

The Development of Sorafenib in HCC

Recently interest has focussed on the ubiquitous Raf-mitogen-activated protein kinase/extracellular signal-related kinase kinase (MEK)-extracellular signal-related kinase (ERK) signalling pathway (Raf/MEK/ERK).This has a major role in the regulation of cell proliferation, survival and differentiation [START_REF] Downward | Targeting RAS signalling pathways in cancer therapy[END_REF]. Dysregulated signalling via Raf is associated with the development of solid tumours [START_REF] Downward | Targeting RAS signalling pathways in cancer therapy[END_REF][START_REF] Hilger | The Ras-Raf-MEK-ERK pathway in the treatment of cancer[END_REF]. The MAPK pathway includes a cascade of phosphorylation events involving at least four well characterised kinases; ras, raf, mitogenactivated protein (MAP) extracellular kinase, and extracellular signal-regulated kinases (ERK).

N-ras mutations are found in HCC, haematological malignancies and melanoma [START_REF] Adjei | Blocking oncogenic Ras signaling for cancer therapy[END_REF], whereas K-ras mutations are found in pancreatic cancer, non-small-cell lung cancer [START_REF] Adjei | Blocking oncogenic Ras signaling for cancer therapy[END_REF] and colorectal cancer (CRC) [START_REF] Pollock | Oncogenic K-RAS is required to maintain changes in cytoskeletal organization, adhesion, and motility in colon cancer cells[END_REF]. Overactivation of receptor tyrosine kinases (RTKs) such as vascular endothelial growth factor receptor (VEGFR)-2/-3, platelet-derived growth factor receptor (PDGFR)-ß, and epidermal growth factor receptor (EGFR), as a result of either activating mutations or overexpression of their growth factor ligands, can result in aberrant signalling through Raf, dysregulated cell growth, and cancer [START_REF] Downward | Targeting RAS signalling pathways in cancer therapy[END_REF][START_REF] Hilger | The Ras-Raf-MEK-ERK pathway in the treatment of cancer[END_REF][START_REF] Zwick | Receptor tyrosine kinases as targets for anticancer drugs[END_REF].

Both angiogenesis and signalling through the Raf/MEK/ ERK cascade play critical roles in the development of HCC. Several authors have described an increase in the expression and activity of these signalling intermediates in the MAPK pathway in HCC cell lines, in in vivo models, and human tumour specimens [START_REF] Feng | Effect of phosphorylation of MAPK and Stat3 and expression of c-fos and cjun proteins on hepatocarcinogenesis and their clinical significance[END_REF][START_REF] Ito | Activation of mitogen-activated protein kinases/extracellular signal-regulated kinases in human hepatocellular carcinoma[END_REF][START_REF] Mckillop | Altered expression of mitogen-activated protein kinases in a rat model of experimental hepatocellular carcinoma[END_REF][START_REF] Schmidt | Increased MAPK expression and activity in primary human hepatocellular carcinoma[END_REF][START_REF] Toyoda | Increased activity and expression of MAP kinase in HCC model rats induced by 3'-methyl-4-dimethylamino-azobenzene[END_REF]. Furthermore, treatment of HCC cells with a MEK inhibitor reduces cell proliferation and induces apoptosis [START_REF] Wiesenauer | Multiple anticancer effects of blocking MEK-ERK signaling in hepatocellular carcinoma[END_REF]. Therefore, inhibition of angiogenesis and Raf/MEK/ERK signalling may represent an attractive approach for the treatment of HCC.

Sorafenib is an oral multikinase inhibitor that has shown efficacy against a wide variety of tumours in preclinical models [START_REF] Wilhelm | BAY 43-9006 exhibits broad spectrum oral antitumor activity and targets the RAF/MEK/ERK pathway and receptor tyrosine kinases involved in tumor progression and angiogenesis[END_REF]. It has been shown to block tumour cell proliferation and angiogenesis by inhibiting serine/threonine kinases (c-RAF, and mutant and wild type BRAF) as well as the receptor tyrosine kinases VEGFR2 and VEGFR3, PDGFR, FLT3, Ret, and c-KIT [START_REF] Wilhelm | BAY 43-9006 exhibits broad spectrum oral antitumor activity and targets the RAF/MEK/ERK pathway and receptor tyrosine kinases involved in tumor progression and angiogenesis[END_REF][START_REF] Carlomagno | BAY 43-9006 inhibition of oncogenic RET mutants[END_REF]. It has also been reported that sorafenib induces apoptosis in human leukaemia cells [START_REF] Rahmani | Apoptosis induced by the kinase inhibitor BAY 43-9006 in human leukemia cells involves down-regulation of Mcl-1 through inhibition of translation[END_REF] and other human tumour cell lines [START_REF] Yu | The role of Mcl-1 downregulation in the proapoptotic activity of the multikinase inhibitor BAY 43-9006[END_REF] through the inhibition of the translation down-regulation of myeloid cell leukaemia-1 (Mcl-1), a Bcl-2 family member. Inhibition of eIF4E by sorafenib in leukaemia cells appears to be independent of the activity on the MEK/ERK pathway [START_REF] Rahmani | Apoptosis induced by the kinase inhibitor BAY 43-9006 in human leukemia cells involves down-regulation of Mcl-1 through inhibition of translation[END_REF], suggesting a possible linkage between eIF4E and translational control of Mcl-1.

Recent findings have demonstrated that the antitumour activity of sorafenib in HCC models may be attributed to inhibition of tumour angiogenesis (VEGFR and PDGFR) and direct effects on tumour cell proliferation/survival (Raf kinase signalling dependent and signalling-independent mechanisms) [START_REF] Liu | Sorafenib blocks the RAF/MEK/ERK pathway, inhibits tumor angiogenesis, and induces tumor cell apoptosis in hepatocellular carcinoma model PLC/PRF/5[END_REF].

Aberrant activation of the Raf/MEK/ERK signalling pathway has been associated with RCC and HCC tumours [START_REF] Feng | Effect of phosphorylation of MAPK and Stat3 and expression of c-fos and cjun proteins on hepatocarcinogenesis and their clinical significance[END_REF][START_REF] Oka | Constitutive activation of mitogen-activated protein (MAP) kinases in human renal cell carcinoma[END_REF], in addition to there being an overexpression of angiogenic growth factors such as VEGF, and their receptors which signal through Raf. There is therefore a solid scientific rationale for investigating the use of Sorafenib in these tumour types as it blocks tumour cell proliferation by targeting the Raf/MEK/ERK signalling at the level of Raf kinase, and exerts an antiangiogenic effect by targeting VEGF-2/-3, and PDGFR-ß tyrosine kinases [START_REF] Wilhelm | BAY 43-9006 exhibits broad spectrum oral antitumor activity and targets the RAF/MEK/ERK pathway and receptor tyrosine kinases involved in tumor progression and angiogenesis[END_REF]. Sorafenib has been investigated as monotherapy in four phase I trials in patients with advanced refractory solid tumours [START_REF] Strumberg | Phase I clinical and pharmacokinetic study of the Novel Raf kinase and vascular endothelial growth factor receptor inhibitor BAY 43-9006 in patients with advanced refractory solid tumors[END_REF][START_REF] Moore | Phase I study to determine the safety and pharmacokinetics of the novel Raf kinase and VEGFR inhibitor BAY 43-9006, administered for 28 days on/7 days off in patients with advanced, refractory solid tumors[END_REF][START_REF] Awada | Phase I safety and pharmacokinetics of BAY 43-9006 administered for 21 days on/7 days off in patients with advanced, refractory solid tumours[END_REF][START_REF] Clark | Safety and pharmacokinetics of the dual action Raf kinase and vascular endothelial growth factor receptor inhibitor, BAY 43-9006, in patients with advanced, refractory solid tumors[END_REF] and demonstrated preliminary activity in tumour types including renal cell carcinoma (RCC), HCC and CRC. Sorafenib was mostly associated with durable disease stabilisation, while two patients (one each with RCC and HCC) had partial responses [START_REF] Strumberg | Phase I clinical and pharmacokinetic study of the Novel Raf kinase and vascular endothelial growth factor receptor inhibitor BAY 43-9006 in patients with advanced refractory solid tumors[END_REF].Prolonged (> 6momths) disease stabilisation was reported in a total of eight patients (18%) including four with CRC and two with HCC who were treated continuously with sorafenib [START_REF] Strumberg | Phase I clinical and pharmacokinetic study of the Novel Raf kinase and vascular endothelial growth factor receptor inhibitor BAY 43-9006 in patients with advanced refractory solid tumors[END_REF].

In addition five of these patients (11%) had stable disease for > 1 year.

Results from the four phase I trials show that most patients experienced drug related adverse events, including fatigue, diarrhoea, and skin toxicities. These were mainly mild to moderate and manageable by dose reduction or cessation of treatment. Dose limiting toxicities such as skin toxicities, diarrhoea and fatigue predominantly occurred at the higher doses (600 and 800mg twice daily) across the four trials, but were relatively infrequent at lower doses the maximum tolerated dose (MTD) was determined to be 400mg twice daily. At the MTD of 400mg twice daily, the continuous dosing schedule was not associated with dose limiting toxicities or significant grade 3 or 4 toxicities [START_REF] Strumberg | Phase I clinical and pharmacokinetic study of the Novel Raf kinase and vascular endothelial growth factor receptor inhibitor BAY 43-9006 in patients with advanced refractory solid tumors[END_REF].

Phase II studies have confirmed that a continuous 400mg twice daily dosing schedule has disease stabilising effects in patients with advanced refractory RCC and HCC [START_REF] Ratain | Phase II placebo-controlled randomized discontinuation trial of sorafenib in patients with metastatic renal cell carcinoma[END_REF][START_REF] Abou-Alfa | Phase II study of sorafenib in patients with advanced hepatocellular carcinoma[END_REF]. Furthermore results from the phase III TARGETs trial have shown that Sorafenib at 400mg twice daily, significantly prolonged progression-free survival versus placebo in patients with advanced, treatment-refractory RCC (5.5 months versus 2.8 months p<0.01) and with an acceptable riskbenefit ratio for toxicities [START_REF] Escudier | Sorafenib in advanced clear-cell renal-cell carcinoma[END_REF].

Results of Phase II and III trials of Sorafenib in advanced HCC.

A phase II trial of sorafenib in advanced HCC was prompted on the background of the a confirmed partial response in a phase I trial as detailed above [START_REF] Strumberg | Phase I clinical and pharmacokinetic study of the Novel Raf kinase and vascular endothelial growth factor receptor inhibitor BAY 43-9006 in patients with advanced refractory solid tumors[END_REF] and a strong scientific rationale for its rationale based on the importance of VEGF and Raf/MEK/KRK signalling in HCC. This was a multicentre, international phase II trial [START_REF] Abou-Alfa | Phase II study of sorafenib in patients with advanced hepatocellular carcinoma[END_REF] in previously untreated patients with Child-Pugh A or B inoperable HCC and ECOG performance status (PS) of 0 or 1. Patients received sorafenib 400mg twice daily continuously until disease progression or unacceptable drug-related toxicities occurred. Up to two dose reductions and a recovery time of up to 3 weeks were allowed for drug related toxicities prior to the need for treatment cessation.

Of 137 patients treated, 3 patients (2.2%) achieved a partial response and 46 (33.6%) had stable disease for at least 16 weeks. Median time to progression was 4.2 months and median overall survival was 9.2 months. These results compare favourably with single agent and combination chemotherapy regimens [START_REF] Yeo | A randomized phase III study of doxorubicin versus cisplatin/interferon alpha-2b/doxorubicin/fluorouracil (PIAF) combination chemotherapy for unresectable hepatocellular carcinoma[END_REF] and with a more favourable toxicity profile. The most common drug-related adverse events were dermatological, constitutional and gastrointestinal symptoms.

Relatively infrequent dose-limiting toxicities were observed with no grade 4 toxicities and grade 3 toxicities of fatigue (9.5%), diarrhoea (8.0%) and hand-foot syndrome (5.1%). Sorafenib was equally well tolerated between Child-Pugh A and B patients.

Several biomarkers have been shown to have potential predictive significance in HCC [START_REF] Qin | Recent progress in predictive biomarkers for metastatic recurrence of human hepatocellular carcinoma: a review of the literature[END_REF][START_REF] Deprimo | Expression profiling of blood samples from an SU5416 Phase III metastatic colorectal cancer clinical trial: a novel strategy for biomarker identification[END_REF].

Because the Raf/MEK/ERK pathway has a significant role in HCC and is targeted by sorafenib, it has been proposed that the active form of ERK, phosphorylated ERK (pERK) may be a useful biomarker. This hypothesis was explored by Abou-Alfa et al and analysed tissue for tumour-cell pERK in 33 patients [START_REF] Abou-Alfa | Phase II study of sorafenib in patients with advanced hepatocellular carcinoma[END_REF]. Staining was most intense in nuclei of tumour cells consistent with translocalisation of pERK to the nucleus after activation [START_REF] Khokhlatchev | Phosphorylation of the MAP kinase ERK2 promotes its homodimerization and nuclear translocation[END_REF]. Furthermore, HCC patients whose tumours expressed higher baseline pERK levels had a longer TTP following treatment with Sorafenib suggesting that higher levels of pERK may correlate with sensitivity or responsiveness to Sorafenib.

White blood cells (WBCs) and peripheral blood mononuclear cells (PBMNCs) as the main source of RNA isolated from whole blood, are considered a "surrogate tissue" relative to a primary tumour or metastasis [START_REF] Qin | Recent progress in predictive biomarkers for metastatic recurrence of human hepatocellular carcinoma: a review of the literature[END_REF]. Therefore gene-expression patterns of WBCs and PBMNCs can be a molecular signature of a tumour that provides information on histological stage or potential to respond to treatment. RNA expression data from Abou-Alfa et al whilst encouraging was not sufficient to distinguish a panel of genes that distinguished nonprogressors from A large, multicentred, randomised, placebo-controlled phase III trial was conducted by Llovet et al to evaluate the safety and efficacy of sorafenib versus placebo in patients with advanced unresectable HCC not amenable to locoregional therapy [START_REF] Llovet | Sorafenib in advanced hepatocellular carcinoma[END_REF]. Patients were required to have advanced measurable HCC and no prior systemic therapy, Child-Pugh classification A and ECOG PS 0-2. Six hundred and two patients were randomised to either sorafenib 400mg twice daily or placebo.

Based on 321 deaths (143 in Sorafenib treated patients and 178 in the placebo group), the hazard ratio (HR) for overall survival (OS) of sorafenib versus placebo treated patients was 0.69 (96% CI: 0.55, 0.87; p=0.0006). This represented a 44% improvement in OS for sorafenib versus placebo which met early stopping criteria. Median OS was 10.7 months for the sorafenib group versus 7.9 months in the placebo group. The second primary end point of the study, time to symptomatic progression demonstrated no statistically significant difference. This in may in part be due to the absence of an appropriate tool for measuring quality of life in this population as the median time to progression was longer in the Sorafenib group (5.5 versus 2.8 months p=0.000007).

The incidence of serious adverse events was similar in both groups (52% versus 54% for sorafenib versus placebo. The most frequent grade 3/4 events were diarrhea (11% versus 2%), hand-foot syndrome (8% versus 1%), fatigue (10% versus 15%) and bleeding (6% versus 9%) for sorafenib versus placebo.

At the European Cancer Conference in September 2007 results of a randomized phase II study comparing placebo and doxorubicin with sorafenib and doxorubicin in 96 patients with advanced HCC were reported [START_REF] Abou-Alfa | ECC Meeting Abstracts[END_REF]. As with the sorafenib monotherapy trial the trial was unblinded on the recommendation of the Data Safety Monitoring Board. The analysis demonstrated highly significant improvements in time to progression (2.8 months versus 8.5 months) and overall survival (5.6 months v 14.0 months).

Conclusions and Future Directions

Given the lack of benefit derived from cytotoxic chemotherapy regimens in the treatment of advanced HCC, future hope seems directed towards the novel targeted agents. Research continues to investigate the key mechanisms of hepatocarcinogenesis and identify key molecular targets for potential therapeutic interventions. The heterogeneity and the underlying medical problems associated with this disease safety and toxicity profiles are of paramount importance when assessing the benefits of a novel therapeutic agent. Whilst establishing the effectiveness of the newer molecularly targeted therapies it is important to establish the relevance of disease stabilization and progression free survival as potential end points given the cytostatic rather than cytotoxic mode of activity. In addition the identification of potential surrogate markers for disease response may help to more effectively establish those who may derive benefit from newer therapies.

Two recently reported trials have demonstrated significant improvements in survival with sorafenib both as a monotherapy [START_REF] Llovet | Sorafenib in advanced hepatocellular carcinoma[END_REF] and in combination with doxorubicin compared to control groups [START_REF] Abou-Alfa | ECC Meeting Abstracts[END_REF]. This establishes sorafenib as a new standard of care for patients with advanced HCC not amenable to locoregional therapy. Further research may elucidate the optimal schedule of administration. In addition, its role as an adjuvant therapy following both surgery and chemoembolisation require investigating.

  combination chemotherapy regimens has been studied in advanced HCC.

  -based and genomic analyses would undoubtedly advance the discovery of new biomarkers and help refine treatment criteria and patient selection.

Table 1 .

 1 The Child-Pugh Classification system.

	Variable	Score 1	Score 2	Score 3
	Bilirubin (mg/dl)	<2.0	2-3	>3.0
	Albumin (g/l)	>3.5	3.5-2.8	<2.8
	PT (INR)	<1.7	1.7-2.3	>2.3
	Ascites	Absent	Mild to moderate	Severe/refractory
	Encephalopathy	Absent	Mild	Severe
	Class A: 5-6 points, Class B: 7-9 points, Class C: 10-15 points.

Abbreviations: INR, International Normalised Ratio; PT; Prothrombin time.

Adapted from Schwartz et al

[START_REF] Schwartz | Strategies for the management of hepatocellular carcinoma[END_REF]

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[START_REF] Yeo | A randomized phase III study of doxorubicin versus cisplatin/interferon alpha-2b/doxorubicin/fluorouracil (PIAF) combination chemotherapy for unresectable hepatocellular carcinoma[END_REF]

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International Journal of Clinical PracticeInternational Journal of Clinical Practice


Anne Katrin Sjoelie
email: a.k.sjoelie@ouh.regionsyddanmark.dk

Paul Dodson

Richard Hobbs

Anne Katrin Sjølie

Fr Richard Hobbs

Anne Katrin Sjølie

Does renin-angiotensin system blockade have a role in preventing diabetic retinopathy? A clinical review

Summary

Diabetes management has increasingly focused on the prevention of macrovascular disease, in particular for type 2 diabetes. Diabetic retinopathy, one of the main microvascular complications of diabetes, is also an important public health problem.

Much of the care invested in retinopathy relates to treatment rather than prevention of disease. Tight glycaemic and blood pressure control helps to reduce the risk of retinopathy but this is not easy to achieve in practice and additional treatments are needed for both primary and secondary prevention of retinopathy. A renin angiotensin system (RAS) has been identified in the eye and found to be upregulated in retinopathy. This has led to specific interest in the role of RAS blockade in retinopathy prevention. The recent DIRECT programme assessed use of the angiotensin receptor blocker (ARB) candesartan in type 1 and type 2 diabetes. Although the primary trial endpoints were not met, there was a clear trend to less severe retinopathy with RAS blockade. A smaller trial, RASS, reported reduced retinopathy progression in type 1 diabetes from RAS blockade with both the ARB losartan and the angiotensin converting enzyme (ACE) inhibitor enalapril.

The clinical implications of these new data are discussed.

How did you gather, select and analyze the information you considered in your review?

The information for this review was gathered at an advisory meeting held to discuss diabetic retinopathy and its prevention in the light of new clinical trial data on renin angiotensin system blockade What is the take home message for the clinician?

• Good control of glycaemia and blood pressure is central to reducing risk of diabetic retinopathy but is not easy to achieve.

• There is a need for additional therapy for prevention of retinopathy development and progression and new clinical trial evidence suggests that drugs that block the renin angiotensin system may be effective. The aim of this review was to evaluate the data on prevention of diabetic retinopathy development and progression, specifically considering new clinical trial data on the possible effect of drugs that inhibit the renin angiotensin system.

Causes of visual problems

There are two main causes of visual problems in diabetic retinopathy: proliferative retinopathy and maculopathy (macular oedema).

Diabetic retinopathy is characterised by capillary dilatation and leakage of lipoproteins and blood, capillary occlusion and subsequent new vessel formation. In type 1 diabetes, the most common cause of visual loss is proliferative retinopathy, which may lead to severe haemorrhage into the vitreous; in type 2 diabetes, the most common cause is macular oedema, caused by breakdown of the blood retinal barrier. However, both types of sight threatening manifestations may occur in all diabetic patients, and may also occur together [START_REF] Sjolie | The retinal renin-angiotensin system: implications for therapy in diabetic retinopathy[END_REF].

Proliferative retinopathy can lead to profound global sight loss while macular oedema can cause gradual and largely irreversible loss of central vision, and these two sight threatening manifestations often occur together in the same eye.

Chronic hyperglycemia is an initiating factor for the retinal changes in diabetes, but the exact mechanism by which retinopathy develops is not clearly established. A number of biochemical pathways have been identified that modulate the disease process through

Modifiable risk factors

The major modifiable risk factors for diabetic retinopathy are high blood sugar and blood pressure. The UKPDS and DCCT showed that intensive glycaemic control [START_REF] Uk Prospective | Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33)[END_REF][START_REF] Control | The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus[END_REF] can reduce risk of developing diabetic retinopathy and slow progression of existing retinopathy. The UKPDS also showed that tight blood pressure control ( 14) reduced visual loss in people with type 2 diabetes.

DCCT and UKPDS indicated that the lower the glycaemia, the lower the risk of retinopathy. Two recent studies, the ACCORD (Action to Control Cardiovascular Risk in Diabetes) Eye study [START_REF]ACCORD study group and ACCORD Eye study group. Effects of medical therapies on retinopathy progression in type 2 diabetes[END_REF] and the ADVANCE (Action in Diabetes and Vascular Disease:

Preterax and Diamicron Modified Release Controlled Evaluation) Retinal Measurements (AdRem) study, [START_REF] Beulens | Effects of blood pressure lowering and intensive glucose control on the incidence and progression of retinopathy in patients with type 2 diabetes mellitus: a randomised controlled trial[END_REF] assessed the effect of intensive glucose lowering in type 2 diabetes, aiming for greater HbA1c reduction than achieved in UKPDS. In the ACCORD Eye study, intensive glycaemic control reduced progression of retinopathy [START_REF]ACCORD study group and ACCORD Eye study group. Effects of medical therapies on retinopathy progression in type 2 diabetes[END_REF]. In AdRem, intensive glycaemic control did not significantly reduce incidence and progression of retinopathy although a trend to benefit was seen [START_REF] Beulens | Effects of blood pressure lowering and intensive glucose control on the incidence and progression of retinopathy in patients with type 2 diabetes mellitus: a randomised controlled trial[END_REF].

Lowering blood pressure in hypertensive diabetes patients reduces both macrovascular and microvascular risk. Blood pressure targets in diabetes get ever lower: the British Hypertension Society and the European Society of Cardiology both recommend a target of <130/80mm Hg [START_REF] Williams | Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, 2004 -BHS IV[END_REF][START_REF]Task Force on Diabetes and Cardiovascular Diseases of the European Society of Cardiology and of the European Association for the Study of Diabetes. Guidelines on diabetes, pre-diabetes, and cardiovascular diseases[END_REF].

In the ACCORD Eye study, intensive blood pressure control (target <120 mmHg) did not have a significant effect on retinopathy progression when compared with standard treatment (target <140mm Hg) [START_REF]ACCORD study group and ACCORD Eye study group. Effects of medical therapies on retinopathy progression in type 2 diabetes[END_REF]. However, both treatment groups in ACCORD had 6 lower blood pressure than in the UKPDS tight control arm, indicating that there may be a threshold below which benefits cannot be obtained for retinopathy progression.

There is conflicting evidence on whether elevated lipids levels are a risk factor for retinopathy, but many patients with diabetes will already be taking statins for cardiovascular disease prevention. In the FIELD (Fenofibrate Intervention and Event

Lowering in Diabetes) trial in type 2 diabetes, fenofibrate reduced the need for laser treatment for retinopathy [START_REF] Keech | Effect of fenofibrate on the need for laser treatment for diabetic retinopathy (FIELD study): a randomised controlled trial[END_REF]. The beneficial effect was not related to plasma lipid levels, suggesting that the drug might have some other, as yet unknown, effect. These data are interesting but require confirmation, particularly as need for laser treatment was only a tertiary endpoint, and was performed at the discretion of the treating physician.

Some further data on this come from the ACCORD Eye study which compared two treatments of dyslipidaemia (simvastatin alone or a combination of simvastatin and fenofibrate) and reported that the combination treatment, which was associated with reduced triglyceride levels, reduced progression of retinopathy [START_REF]ACCORD study group and ACCORD Eye study group. Effects of medical therapies on retinopathy progression in type 2 diabetes[END_REF].

Medical management of diabetic retinopathy

Tight control of blood glucose and blood pressure is key to primary and secondary prevention of diabetic retinopathy, but is difficult to achieve in practice. Tight glucose control can be limited by risk of hypoglycaemia, particularly in type 1 diabetes, and fear of hypoglycaemia can be a barrier to adherence [START_REF] Alvarez Guisasola | Hypoglycaemic symptoms, treatment satisfaction, adherence and their associations with glycaemic goal in patients with type 2 diabetes mellitus: findings from the Real-Life Effectiveness and Care Patterns of Diabetes Management (RECAP-DM) study[END_REF].

In the UK, control of glycaemia and blood pressure in patients with diabetes has been steadily improving, but less than 80% of patients have blood pressure ≤145/85mmHg (the Quality and Outcomes Framework standard) and less than 70% have HbA1c ≤7.4% [START_REF]Five years on. Delivering the Diabetes National Service Framework[END_REF].

A recent US study reported that for patients with diabetes treated in primary care clinics only 34% met an HbA1c target of <7% and only 30% met a blood pressure target of <130/80mm Hg [START_REF] Grant | Quality of diabetes care in US academic medical centers[END_REF]. Even with good control, retinopathy remains an important clinical problem and there is a need for additional treatments to reduce risk.

RAS and diabetic retinopathy

Among new approaches to retinopathy prevention there has been considerable interest in whether drugs that block the renin angiotensin system (RAS) might have a preventive effect, over and above their blood pressure lowering effect. RAS blockade can slow the progression of diabetic nephropathy (23) and there is growing evidence that the RAS may also play an important role in the pathogenesis of diabetic retinopathy A local renin-angiotensin system has been shown to operate in the eye and there is evidence from clinical and experimental models that this system is upregulated in active retinopathy. Angiotensin II has been shown to increase exudation from retinal vessels [START_REF] Aiello | Vascular endothelial growth factor in ocular fluid of patients with diabetic retinopathy and other retinal disorders[END_REF], as well as stimulate formation of new retinal blood vessels, via upregulation of vascular endothelial growth factor (VEGF) activity and other growth factors, and studies in animal models suggest that RAS blockade might be associated with protective effects on the retina [START_REF] Sjolie | The retinal renin-angiotensin system: implications for therapy in diabetic retinopathy[END_REF][START_REF] Wilkinson-Berka | Angiotensin and diabetic retinopathy[END_REF].

Small short-term clinical studies have also demonstrated beneficial effect of RAS blockade on retinal permeability [START_REF] Larsen | Protective effect of captopril on the blood-retina barrier in normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy[END_REF][START_REF] Chase | Angiotensin-converting enzyme inhibitor treatment for young normotensive diabetic subjects; a two year trial[END_REF]. These findings could indicate a long-term beneficial effect on diabetic retinopathy.

In the EURODIAB Controlled Trial of Lisinopril in Insulin-Dependent Diabetes (EUCLID), treatment with the angiotensin converting enzyme (ACE) inhibitor was associated with a non-significant reduction in incidence of retinopathy and a significant reduction in retinopathy progression in normotensive patients with type 1 diabetes (28).

However, these data were not conclusive because retinopathy was not a primary trial endpoint; also, patients randomised to lisinopril had lower HbA1c levels at baseline than placebo patients. severity scale. This is the gold standard for evaluating diabetic retinopathy in clinical trials and is based on grading seven-field stereo photographs of the eyes. The primary trial endpoint was at least a two-step increase on the ETDRS scale for incidence and at least a three-step increase for progression. A secondary endpoint was regression of retinopathy, defined as either reduction of at least three steps from baseline on any follow-up visit, or two or more steps sustained on two visits one year apart. In DIRECT-Prevent 1 (29), candesartan reduced the incidence of retinopathy by 18% (HR 0.82, P=0.0508). Although this primary endpoint just missed conventional levels of statistical significance, in a post hoc analysis of three-step increase -a more stringent criteria for development of retinopathy -there was significant benefit in favour of active treatment (HR 0.65, P=0.0034), which was reduced but still significant (HR 0.74, P=0.046) when the results were adjusted for baseline characteristics and small changes in blood pressure during the trial.

In DIRECT-Protect 1 (29), there was no significant difference between candesartan and placebo in retinopathy progression in patients with type I diabetes (P=0.85).

In DIRECT-Protect 2 (30), retinopathy progression was reduced by 13% in the candesartan group, which was not statistically significant (HR 0.87, P=0.20). However, the secondary endpoint of retinopathy regression was increased by 34% with candesartan treatment (HR 1.34. P=0.009), and this was still significant (P=0.015) after adjustment for baseline variables and blood pressure during the course of the trial. Regression was only seen in patients with mild retinopathy, supporting the hypothesis that retinopathy might reach a "point of no return".

Adverse event were similar in active and placebo groups in the three trials.

Although DIRECT did not meet its primary endpoints, there was an overall change towards less severe retinopathy in both type 1 and 2 diabetes. For all three trials, the final ETDRS level -also a predefined endpoint -was more likely to have improved in candesartan patients than in placebo patients (Figure 1), suggesting that the active treatment has a biological effect on the disease process.

The mechanism for candesartan's apparent beneficial effect has not been examined in the DIRECT Programme. It may be partially related to blood pressure lowering with a possible additional specific effect of RAS blockade on the eye, as the effects shown in the

RASS trial

Further support for a beneficial effect on diabetic retinopathy from RAS blockade comes from the RASS (Renin-Angiotensin System Study) which evaluated whether RAS blockade can slow retinopathy progression in type 1 diabetes [START_REF] Mauer | Renal and retinal effects of enalapril and losartan in type 1 diabetes[END_REF]. In this study nephropathy was the primary endpoint, and retinopathy was another prespecified endpoint.

RASS compared the ACE inhibitor enalapril 20mg daily, the ARB losartan 100mg daily, and placebo in 223 normotensive patients, with mean age 30 years. At baseline, over 90% of patients had either no diabetic retinopathy (34%) or minimal / early non-proliferative retinopathy (58%). Only 9% had moderate to severe non-proliferative retinopathy. There was no significant difference in baseline retinopathy levels in the three groups.

The study retinopathy endpoints were progression of two steps or more or three steps or more on the ETDRS severity scale. After five years, retinopathy progression occurred in 38% of patients receiving placebo compared with 25% of patients on enalapril (P=0.02) and 21% of patients on losartan (P=0.008).

The effects of the active treatments remained after adjustment for mean blood pressure measurements during the study, although the study authors report that effects of blood pressure on the retinopathy outcomes cannot be ruled out.

In both DIRECT and RASS, patients were normoalbuminuric at baseline. Unexpectedly, given the known beneficial effect of RAS inhibition in patients with more advanced nephropathy, neither trial showed any statistically significant effect of RAS blockade on development of microalbuminuria [START_REF] Mauer | Renal and retinal effects of enalapril and losartan in type 1 diabetes[END_REF][START_REF] Bilous | Effect of candesartan on microalbuminuria and albumin excretion rate in diabetes[END_REF].

Clinical implications of the RAS studies

Prevention of diabetic retinopathy and its progression is highly relevant to general practitioners as nearly all type 2 diabetes and the majority of type 1 diabetes in an increasing number of European countries is now managed in primary care.

It is perhaps not surprising that the DIRECT trials did not meet their primary endpoints.

Retinopathy incidence and progression was lower than expected, and this is probably because the trial population was younger and better controlled than most patients seen in everyday practice. With this "healthier" population, four years may have been too short a period to show benefit.

Nonetheless, the DIRECT trials do show a strong trend to shifting the risk of retinopathy in the diabetic population (Figure 1). We believe that some suggestions can be made regarding clinical implications of the data.

For secondary prevention in patients with type 2 diabetes, RAS blockade fits well into the current multifactorial intervention strategies. Most patients with diabetes will become hypertensive at some point and standard practice is to prescribe an RAS inhibitor as a key component of the antihypertensive therapy for reno-protection.

The recent data further suggest that RAS blockade in earlier stages of retinopathy may be effective, and that those that benefit the most are people whose retinopathy progresses rapidly. The problem is that these population phenotypes are not identifiable in routine practice. Therefore, if a prescriber has any reason to consider using a drug that modifies the RAS in patients with diabetes, such as hypertension, the new data offer a compelling argument to think about prescribing this treatment earlier, in patients with early retinopathy. More intensive treatment might also be considered, bearing in mind the relatively high candesartan dose of 32mg used in DIRECT.

Conclusion

Microvascular complications remain important causes of morbidity. They also contribute significantly to the cost of treating diabetes in the long-term, and will become more common as the incidence of the disease increases and more people with diabetes survive macrovascular complications.

There is an unmet need in retinopathy prevention and the new data on RAS blockade are encouraging. It is not yet clear whether RAS blockade has direct effects on the eye or whether the effect on retinopathy is largely explained by blood pressure lowering, but this is of little consequence for day-to-day clinical practice. Blood pressure targets in diabetes are getting lower and the DIRECT data add weight to existing evidence to consider use of an RAS blocker as antihypertensive agent in patients with diabetes.

F

  Does renin-angiotensin system blockade have a role in preventing diabetic retinopathy? A clinical review

  metabolism, signalling and growth factors[START_REF] Wright | Diabetic retinopathy and blockade of the renin-angiotensin system: new data from the DIRECT study programme[END_REF] and these have led to investigation of new treatment targets.

  Following the positive results from EUCLID, the DIRECT (Diabetic Retinopathy Candesartan Trials) programme was set up to assess further the effects of RAS blockade on diabetic retinopathy. The programme involved three placebo-controlled trials evaluating the effect of the angiotensin receptor blocker (ARB) candesartan 32mg daily on the incidence of new retinopathy and the progression of retinopathy in type 1 (29) and type 2 (30) diabetes. DIRECT involved 5231 patients, making it the largest trial that has been carried out with diabetic retinopathy as the primary endpoint. Prevention of retinopathy and progression of established retinopathy was assessed in type 1 diabetes and progression of retinopathy in type 2 diabetes, with follow-up for at least four years. The three components of the DIRECT programme were: DIRECT-Prevent 1 -1421 patients with type 1 diabetes (mean age 30) who were normotensive and had no retinopathy at baseline; DIRECT-Protect 1 -1905 patients with type 1 diabetes (mean age 32) who were normotensive and had mild-moderate non-proliferative retinopathy at baseline; and DIRECT-Protect 2 -1905 patients with type 2 diabetes (mean age 57) who were normotensive (BP < 130/85) or mildly hypertensive (BP < 160/90) and being treated, and had mild-moderate non-proliferative retinopathy at baseline. Retinopathy was assessed on the ETDRS (Early Treatment Diabetic Retinopathy Study)

  significant after adjustment for blood pressure. Further analysis may help to clarify these mechanisms.

Page 12 of 18 International Journal of Clinical Practice International Journal of Clinical Practice

  For preventing retinopathy in type 1 diabetes, further research is needed to identify highrisk patients, for example those who are unable to obtain good glycaemic control, who might benefit from RAS blockade. But at present the evidence does not justify routine use of an RAS blocker in a metabolically well-controlled normotensive, normoalbuminuric patient with type I diabetes.

	F o
	r
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  Overall change in Early Treatment Diabetic Retinopathy Study (ETDRS) level from baseline to final visit in the DIRECT programme (adapted, with permission, from references29 and 30)

	o F o F o F o F o
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	R e v i e w R e v i e w R e v i e w R e v i e w R e v i e w
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	l y l y l y l y l y
	13

Acknowledgements

Editorial assistance to the authors was funded by Takeda Pharmaceuticals Europe.

AK Sjølie received honoraria as a member of the DIRECT Programme Steering Committee. P Dodson and FDR Hobbs have been on advisory boards for the DIRECT Programme.

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Author contributions

All authors contributed to discussion on the content of the paper and critical revision of the paper Figure 1


James Matthew

Lloyd Williamson

David B Hocken

James Ml Williamson

Assessing the internet prevalence of cancer

Introduction

The internet is one of the most frequently accessed sources of information by patients. There is a variety of cancer related information provided by the internet, aimed at both the general public (from official sites and non-regulated sites) and for health care professionals. Little is known about whether the information provided reflects the prevalence of disease.

Methods

Searches for the 10 most common UK cancers were performed using 5 internet search engines. The number of relevant webpages was recorded and compared to the prevalence of each cancer according to Cancer Research UK.

Results

Of the 985687623 webpages identified, the majority were related to breast cancer (37.2%), followed by lung (16.2%) and prostate cancer (12.5%).

Colorectal cancer, Oesophageal cancer and Non-Hodgkin's lymphoma had the least number of websites (4.1%, 0.3% and 0.9% respectively). There was over-representation of breast, kidney and stomach cancer with ratios of prevalence to number of websites of 1.7, 2.6 and 2.5 to 1 respectively. There was under-representation of colorectal cancer, non-Hodgkin's lymphoma and oesophageal cancer (ratios 0.2, 0.2 and 0.1 respectively).

Conclusion

This data highlights the enormity of information available on the internet. However, there is over-representation of certain cancers (and underrepresentation of others) which may influence how patients perceive their

illness. Healthcare professionals should be aware of the nature of information available on the internet and known when and how to direct patients to reputable sites that provide high quality information.

What's known about this subject?

The Internet has a large number of webpages related to cancer, from both official and unofficial sources. Little is known if the number of webpages is representative to the overall incidence of cancer

What's new?

This paper highlights the fact that certain cancers are over-or underrepresented on the internet. This may have an influence on how the general population perceives cancer.

Take home message for the clinic

Patients are increasingly resourceful in retrieving information. Clinicians must be aware of the limitations of internet derived information and should be able to direct patients to official sources of information.

Introduction

The use of the internet to seek health information is common and increasing, particularly among patients with life-threatening or chronic diseases, young adults [START_REF] Biermann | Evaluation of cancer information on the internet[END_REF](19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) and the elderly (65 years and above) [START_REF] Madden | Internet penetration and impact[END_REF][START_REF] Basch | Use of information resources by patients with cancer and their companions[END_REF][START_REF] Ekman | Can we trust cancer information on the internet? -A comparison of interactive cancer risk sites[END_REF]. In 2003 more than 90 million people had sought health information online and 20% of the population of America performed health searches in 2006 [START_REF] Madden | Internet penetration and impact[END_REF][START_REF] Fox | Internet health resources: health searches and email have become more commonplace, but there is room for improvements in searches and overall internet access[END_REF]. Of these online health information seekers, 70% report that the internet influenced decisions about their own or a loved one's health care [START_REF] Fox | Vital descisions. How internet users decide what information to trust when they or their loved ones are sick[END_REF] and more than 1/3 of patients ask clinicans about health websites during consultations [START_REF] Murray | The impact of health information on the internet on the physician-patient relationship: patient perceptions[END_REF]. These patients believe that internet use enhances the doctor-patient relationship [START_REF] Murray | The impact of health information on the internet on the physician-patient relationship: patient perceptions[END_REF][7]. Most health information searches are performed via a online search engine (e.g. A ratio was calculated between cancer prevalence and number of webpages to give a relative internet profile of each malignancy (figure 1). This revealed that there was over-representation of breast, kidney and stomach cancer with ratios of prevalence to number of websites of 1.7, 2.6 and 2.5 to 1 respectively. There was under-representation of colorectal cancer, non-Hodgkin's lymphoma and oesophageal cancer (ratios 0.2, 0.2 and 0.1 respectively). Our data shows that the internet profile of breast, kidney and stomach cancer is over represented. Given the scope of the number of webpages related to each search, the exact content could not be fully assessed. While some of these 'hits' may not be accurate, it is likely that these cancers do have an overall dominance of internet traffic. A possible reason for the dominance of breast cancer is the increased use internet health sites by women [START_REF] Madden | Internet penetration and impact[END_REF].

Colorectal cancer, NHL and oesphageal cancer seem to have a lower than to be expected number of webpages associated with them. It is possible that the search term 'colorectal' may prove too specific a term and (some websites 9 may use the terms colon or rectal cancer) thus there may be an underrecording of websites. However, this term is likely to be used by clinicans in discussion with patients and thus they will perform an internet search with the information given. Oesophagus can be spelt two ways, and thus we may have not accurately recorded all sites that use the American 'esophagus', which may be more common. Two searches were not performed as there may be cross-linkage on the same site and thus duplication of results (link into cancer in media paper and state results similar however).

Perhaps the most alarming feature from the data shows that the number of webpages related to colorectal cancer is far lower than should be expected, especially as this is the second most common cancer in both men and women. One potential reason for this is the taboo associated with its symptoms -rectal bleeding and altered bowel habit may not be the most The unregulated content of the world wide web may result in a distortion of information available to the public. As the internet will have webpages that mention cancer, but are not primarily providing health information, the number of websites that are listed on a websearch is not necessarily representative to overall cancer incidence. Moreover, some of this data will not be suitable for patients and some of these websties will not be from regulated sources [START_REF] Ekman | Can we trust cancer information on the internet? -A comparison of interactive cancer risk sites[END_REF][START_REF] Fox | Internet health resources: health searches and email have become more commonplace, but there is room for improvements in searches and overall internet access[END_REF][START_REF] Murray | The impact of health information on the internet on the physician-patient relationship: patient perceptions[END_REF][START_REF] Berland | Health information on the interent: accessibility, quality, and readability in English and Spanish[END_REF][START_REF] Biermann | Evaluation of cancer information on the internet[END_REF]. Although the majority of health seekers find on-line health information trustworthy, there is concern about the accuracy and quality of internet-derived information [START_REF] Ekman | Can we trust cancer information on the internet? -A comparison of interactive cancer risk sites[END_REF][START_REF] Berland | Health information on the interent: accessibility, quality, and readability in English and Spanish[END_REF]. Acting upon faulty advice or information found on the internet undoubtly causes harm [3.17-18]. As sites sponsored or administered by medical societies and universities are associated with reliability, the reputation and authority of these organisations might be undermined if they provide inaccurate [START_REF] Berland | Health information on the interent: accessibility, quality, and readability in English and Spanish[END_REF][START_REF] Biermann | Evaluation of cancer information on the internet[END_REF]. Potentially some cancers which have a large amount of internet coverage may be percieved at being more common than they truly are, with the converse likely to be true, with underreported malignancies thought to be less common. It can be postulated that the general public will have more understanding of diseases which receive a large amount of internet coverage.

Conclusion

The internet is an ideal medium to dissiminate health information to the public as it is easily accessible, provides information in an interacitve audio-visual format and contains links to other releavant websites. It would be impossible

to regulate all of the information provided on the internet and one of the main appeals of the world wide web is that anyone is free to make their own website. This data does show that there are discrepencies between the prevalence of cancers and the amount of webpages in existence. As clinicans we should be aware of this data as patients may think certain malignancies are more (or less) common than they truly are. We should ensure that patients seeking consultation should be provided with a list of website addresses that are regulated sources of information that can enhance patient understanding and comprehension of their illness.

Legends

Figure 1: The relative internet profile of cancer

Figure 1 :

 1 Figure 1: The relative internet profile of cancer

  appealing of subjects to write about. If harnessed properly the internet could be a powerful tool to help break the taboo's of this disease[15][START_REF] Koller | Symptom reporting in cancer patients: the role of negative affect and experienced social stigma[END_REF]. These patient orientated websites can be invaluable to ensure that patients have a point access to information that they can read at their own leisure. They may improve patient comprehension of their disease and give a realistic expectation of therapy. In addition, it may also have links to local support groups or personal accounts of other cancer sufferes, which can help to break down any feelings of isolation and stigma felt by patients[15][START_REF] Koller | Symptom reporting in cancer patients: the role of negative affect and experienced social stigma[END_REF].

Page

  G, Mudur G, Henry D, Wilson A, Goozner M, Simbra M, Sweet M, Baverstock KA. What are the roles and responsibilites of the media in disseminating health information. PLoS Medicine 2005;2(7):576-582 13: Williamson JML, Hocken DB. Pancreatic cancer in the media: the Swayze shift. Annals of the Royal College of Surgeons of England 2010;92(6):537-8 14: Williamson J, Hocken D. How much vascular disease is reported by the UK media? International Journal of Clinical Practice 2010;64(8):1167-8

Table 1 :

 1 Google, Bing, Yahoo, Ask and Lycros)[8]. The prevalence of each of the most common UK cancers (NHL =ResultsA total of 985,687,623 results were retrieved from all of the 5 search engines on all of the malignancies. Breast cancer received the greatest number of hits

	Internet Search engines provide the user with a list of results based on the
	search, from what they feel is the most to least relevant. They also provide a
	total number of webpages pertinent to the search term. With over 29.7 billion
	webpages in existance (estimate from 2007)[9] and an estimated 82 million
	hits in 2005 on a search for 'cancer' (from Google) there is bound to be some
	overlap on cancer information available on the internet [8]. To date no papers
	have assessed if the number of websites related to cancer is representative to
	the overall prevalence. However, cancers that are more prevalent, have a
	high mortality and have a high media profile are associated with an increased
	level of internet search activity [8].

Table 2 :

 2

The number of webpages about each type of cancer (combined from the major 5 search engines)

Table 1 :

 1 The prevalence of each of the most common UK cancers (NHL =

	Non-Hodgkin's Lymphoma)[10]

Table 2 :

 2 The number of webpages about each type of cancer (combined from

	the major 5 search engines)

http://info.cancerresearchuk.org/cancerstats/index.htm (accessed May 2010) 11: Search Engine Guide (www.searchengineguide.com, accessed August