[The hepato-pulmonary syndrome--where do we stand in the year 2006?]

The hepato-pulmonary syndrome (HPS) is characterized by a combination of liver disease and pulmonary gas exchange abnormalities with arterial hypoxemia, intrapulmonary vasodilatation and arteriovenous shunting in the absence of intrinsic cardiopulmonary disease. The course of the disease is typically progressive. The mortality rate correlates with the pulmonary shunt volume and the degree of hypoxemia at room air. While the patho-physiology of HPS is still not fully understood, a multifactorial etiology is favored. Apart from functional intrapulmonary arteriovenous shunts which appear to represent a major factor in the development of HPS, both ventilation-perfusion mismatch and limited oxygen diffusion contribute to the HPS. Regarding its clinical appearance, pulmonary and hepatic symptoms have to be distinguished. Contrast echocardiography is the primary diagnostic tool. Symptomatically, hypoxemia can be treated with oxygen. So far, the only successful treatment approach which has been tested in larger patient groups, is liver transplantation. Given this background, the aim of this review is to critically discuss current concepts of this serious complication of liver diseases.

B cell targeted therapies: safety considerations

Reported data from recent clinical trials have contributed substantially to our growing understanding of the potential effectiveness and safety of B cell targeted therapy in the treatment of rheumatic diseases. Trials with rituximab, an anti-CD20 monoclonal antibody that depletes mature B cells, have amassed the most data of any B cell targeted therapy to date. A number of other B cell directed therapies are under investigation. Interestingly, although they may share a common target, the different agents have quite distinct mechanisms of action, and therefore their efficacy and safety profiles may differ. A common concern with all B cell directed therapies is the potential effect these agents may have on humoral immunity. The safety profile of rituximab in the oncology setting is well known, based on a database of well over 370,000 patients. Phase II trials of rituximab in rheumatoid arthritis (RA) have begun to examine safety issues specifically in the RA population, including issues surrounding longterm and repeated treatment safety profiles. Questions about the longterm safety of B cell therapy remain to be clarified: What will be the safety profile for repeated treatment courses? What will be the safety profile when B cell targeted therapies are used in sequence or in conjunction with other agents? Answers to these important questions are likely to come from careful observations by treating clinicians, data from registries, and longterm followup of patients enrolled in clinical trials.

Folic acid, inflammation, and atherosclerosis: False hopes or the need for better trials?

An increasing body of evidence supports the existence of a strong link between inflammation, endothelial dysfunction, and the onset and progression of atherosclerosis. However, a cause-effect relationship between these phenomena has not been demonstrated yet. Although some inflammatory markers, such as C-reactive protein, have been recently shown to improve risk stratification and to strongly predict cardiovascular outcome, it is largely unknown whether modifications of these markers might provide salutary effects and reduce cardiovascular morbidity and mortality. The B-vitamin folic acid has recently gained attention because of its potential to provide beneficial effects on surrogate end-points, such as endothelial function, in patients at high cardiovascular risk. However, the role of folic acid in mitigating the pro-inflammatory state associated with atherosclerosis is controversial. Despite the theoretical arguments supporting the potential anti-atherosclerotic and anti-inflammatory effects of folic acid, the current evidence is limited, deriving from small trials on different study populations, using folic acid often in combination with other vitamins and for different treatment periods. This review will consider the current evidence supporting the role of some well-established inflammatory markers in predicting cardiovascular outcomes, the mechanisms by which folic acid might exert anti-inflammatory effects, the epidemiological data relating folic acid concentrations with inflammatory markers, the published interventional studies on the effects of folic acid supplementation on these markers, and the factors that need to be considered in designing future trials.

Actual experience and future development of gemcitabine in superficial bladder cancer

Gemcitabine has a molecular weight of 299 D, lower than that of commonly-used intravesical chemotherapeutic agents such as mitomycin C (389 D) and doxorubicin (589 D). This may enable gemcitabine to penetrate the bladder mucosa with beneficial effects in the treatment of early invasive bladder cancer (T1 disease). At the same time the molecular weight is high enough to prevent significant systemic absorption in an intact bladder. Based on the results of phase I studies, it appears that the 2000 mg dose of gemcitabine in 50/100 ml normal saline when administered intravesically for up to 2 h once a week for 6 weeks has unremarkable systemic and local side effects and therefore should be considered the most convenient schedule. The currently available phase II studies have assessed the activity of intravesical gemcitabine on a marker lesion in intermediate risk superficial bladder cancers (SBC), showing complete responses in up to 56% of cases. Few attempts have been made to test the activity of intravesical gemcitabine in high risk SBC achieving unexpected complete responses in BCG refractory CIS. Gemcitabine seems to have fulfilled the requirements to be a promising new candidate for standard intravesical therapy in SBC so far. Further phase II trials exploring the activity of gemcitabine on highly-recurrent intermediate risk or high risk SBC would provide additional information to foresee its efficacy in clinical practice and thus constitute the framework for large comparative phase III trials.

The potential use of selective 5-HT2C agonists in treating obesity

Activation of central 5-HT2C receptors as a strategy for appetite suppression and weight control is supported by animal pharmacology and human clinical studies. Considerable evidence comes from the weight-loss effects of fenfluramine, a non-selective 5-HT2C agonist. Advances in molecular pharmacology have led to an understanding of the effects of 5-HT2C receptor activation on food intake and satiety, in addition to providing insight into the causes of cardiac valvular insufficiency and pulmonary hypertension associated with the use of fenfluramine. However, clinically validated animal models of drug-induced disease and knowledge of the molecular mechanisms of these safety issues is lacking. For this reason, the development of selective 5-HT2C agonists for the treatment of obesity has remained a challenge.

Is clozapine antisuicidal?

Suicide accounts for approximately 10% of patient deaths in schizophrenia. The atypical antipsychotic clozapine (Clozaril), successful in treatment-resistant patients with schizophrenia, may have an additional antisuicidal effect. Numerous published reports, including the collaborative International Suicide Prevention Trial, have compared mortality rates between clozapine recipients and patients receiving other forms of antipsychotic treatment and observed a significant reduction in patient risk for suicide with clozapine therapy. Preliminary reports indicate improvements in suicidality in schizophrenia patients treated with other modern atypical antipsychotics, for example olanzapine [Zyprexa], risperidone [Risperdal] and sertindole [Serdolect], but further investigation is required to clarify their role as antisuicidal drugs. It has been estimated that 53 suicides in treatment-resistant patients could have been prevented by clozapine, but the number of lives saved may be significantly higher if clozapine therapy was extended to treatment responders at a high risk for suicide.

Sumatriptan: a decade of use and experience in the treatment of migraine

The migraine-specific triptans have revolutionized the treatment of migraine and are usually the drugs of choice to treat a migraine attack in progress. Sumatriptan (Imitrex) has been available for the longest time within the class, is most flexible in form and has been given successfully to the most number of patients. It is useful for the full range of attacks experienced by a migraine suffer. The aim of this review is to provide an overview of the first 10 years of the use of sumatriptan.

Atorvastatin and cardiovascular protection: a review and comparison of recent clinical trials

Until recently, atorvastatin was known only as a new but more potent statin ('me too' drug) for lowering low-density lipoprotein cholesterol. In the last 2 years, data has become available on nearly 32,000 patients, in clinical settings ranging from primary prevention to acute coronary syndromes. These trials show the remarkably consistent clinical benefit of atorvastatin in patients with hypertension, diabetes, acute coronary syndromes, stable coronary disease with reductions in death, myocardial infarction and stroke, as well as in prevention of atherosclerosis progression. In addition, new data are also emerging to suggest that intensive therapy with high dose atorvastatin 80 mg is associated with a greater reduction in inflammatory markers, such as C-reactive protein, compared with other statin regimens. This suggests that intensive therapy with atorvastatin is associated with a potent pleiotropic effect. This review aims to summarise the recently concluded and ongoing clinical trials and to stimulate further reading.

Clinical trials update from the American Heart Association: REPAIR-AMI, ASTAMI, JELIS, MEGA, REVIVE-II, SURVIVE, and PROACTIVE

This article provides information and a commentary on trials presented at the American Heart Association meeting held in November 2005, relevant to the pathophysiology, prevention and treatment of heart failure. All reports should be considered as preliminary data, as analyses may change in the final publication. In REPAIR-AMI an improvement in ejection fraction was observed in post-MI patients following infusion of bone marrow stem cells. However, the ASTAMI study showed no benefit of stem cell implantation in a similar patient cohort. The JELIS study reported a reduction in major coronary events in patients receiving statins plus fish oil compared to statins alone. MEGA showed that low dose statins in a low risk population reduce the incidence of major cardiovascular events. Two studies of levosimendan in acute heart failure gave conflicting results, in the REVIVE-II study levosimendan was reported to have a superior effect on the composite primary outcome compared to placebo, however, in SURVIVE despite a trend to early benefit with levosimendan, there was no difference in effect on long-term outcome versus dobutamine. The PROACTIVE study showed encouraging results for the use of pioglitazone in post-myocardial infarction patients with concomitant type 2 diabetes.

Treatment options for glioblastoma

Following the seminal trial conducted by the European Organisation for Research and Treatment of Cancer (EORTC) and the National Cancer Institute of Canada (NCIC), concurrent temozolomide and radiotherapy has become the new standard of care for patients with newly diagnosed glioblastoma multiforme (GBM). Investigation of emerging therapies (which are now used as salvage therapy) such as small-molecule inhibitors (for example, epidermal growth factor receptor inhibitors) and convection-enhanced delivery (CED) of targeted toxins (for example, interleukin-13/pseudomonas exotoxin) is likely to build on the EORTC/NCIC treatment platform and will, it is hoped, improve survival rates in patients with GBM. The majority of adjuvant Phase I and II trials being conducted by the brain tumor consortia are based on the EORTC/NCIC treatment platform and have added a targeted therapy in an effort to find a promising synergistic treatment. Furthermore, researchers in the consortia are continuing to explore treatments for recurrent GBM, not otherwise eligible for local therapies, such as CED. The treatments under study include novel cytotoxic chemotherapy as well as small-molecule inhibitors; these are being assessed in a variety of Phase I or II trials.

Pegaptanib sodium for the treatment of neovascular age-related macular degeneration

This article reviews pegaptanib sodium, a compound developed by Eyetech Pharmaceuticals Inc. and Pfizer Inc., for the treatment of neovascular age-related macular degeneration (AMD). Traditional treatment approaches to neovascular AMD have included destructive therapies such as thermal laser photocoagulation and photodynamic therapy; the use of pegaptanib sodium heralds a new treatment approach that is a non-destructive therapy based on the inhibition of vascular endothelial growth factor activity in the eye. This diminishes the neovascular drive in the pathologically hyperpermeable state of the diseased eye. Pegaptanib sodium is one of the first therapeutics belonging to the class of compounds known as aptamers. The chemistry, mechanism of action, pharmacokinetics and rationale for the clinical use of the drug are reviewed. The article highlights and summarises the results of the multi-centre, randomised, sham-controlled clinical trials with pegaptanib sodium to treat subfoveal choroidal neovascularisation in AMD. In addition, the safety profile is reviewed.

The benzodiazepine binding site of GABA(A) receptors as a target for the development of novel anxiolytics

Non-selective benzodiazepine (BZ) binding-site full agonists, exemplified by diazepam, act by enhancing the inhibitory effects of GABA at GABA(A) receptors containing either an alpha1, -2, -3 or -5 subunit. However, despite their proven clinical anxiolytic efficacy, such compounds possess a relatively narrow window between doses that produce anxiolysis and those that cause sedation, and are also associated with physical dependence and a potential for abuse. In the late 1980s and early 1990s a number of non-selective partial agonists, exemplified by bretazenil, pazinaclone and abecarnil, were described. Their reduced intrinsic efficacy relative to full agonists such as diazepam resulted in an improved preclinical pharmacological profile in that there was a large window between anxiolytic and sedative doses and their dependence and abuse liabilities were much lower. Unfortunately, these compounds failed, for a variety of reasons, to translate into clinical benefit, and as the public perception of BZs deteriorated interest in the area waned. However, the advent of molecular genetic and pharmacological approaches has begun to delineate which GABA(A) receptor subtypes are associated with the various pharmacological effects of the non-selective BZs. More specifically, the alpha2- and/or alpha3-containing GABA(A) receptors play a role in anxiety whereas the alpha1 subtype is involved in sedation, raising the possibility of a compound that selectively modulates alpha2- and/or alpha3-containing receptors but does not affect alpha1-containing receptors would be a non-sedating anxiolytic. In order to achieve selectivity for the alpha2/alpha3 subtypes relative to alpha1, two approaches may be used; selective affinity or selective efficacy. Selective affinity relies on a compound binding with higher affinity to the alpha2/alpha3 compared with alpha1 subtypes, but to date no such compounds have been described. On the other hand, subtype-selective efficacy relies on a compound binding to all subtypes but having different efficacies at various subtypes (relative selective efficacy, for example SL654198 or pagoclone) or having efficacy at some subtypes but none at others (absolute selective efficacy; for example, L-838417). The status of these and other BZ site compounds with claimed, but often not explicitly stated, GABA(A) subtype selectivity (such as ELB-139 and ocinaplon) will be reviewed in relation to their development as non-sedating anxiolytics for the treatment of generalised anxiety disorder.

Emerging drugs for ovarian cancer

Because most patients presenting with advanced ovarian cancer are not curable by surgery alone, chemotherapy represents an essential component of treatment. The disease may be considered as chemosensitive, as in around three-quarters of patients major (complete) responses are seen to initial treatment with the platinum-containing drugs cisplatin and carboplatin either used alone or in combination with the taxane, paclitaxel. However, only 15-20% of patients experience long-term remission as tumours often become resistant. The probability of achieving a second response depends on the duration of remission after first-line therapy: if this is < 6 months (considered as platinum resistant) second responses are uncommon and usually short-lived; if this is > 6, and especially if > 12 months (platinum sensitive), responses may be seen in about a quarter of patients, to the same drugs as used first line or to drugs such as pegylated liposomal doxorubicin, topotecan and hexamethylmelamine (all three are approved in this setting by the FDA). Gemcitabine, oral etoposide, docetaxel and oxaliplatin also show some activity either in sequential addition to existing approved of first-line therapy (as with gemcitabine) or as second-line therapy. However, there is an urgent unmet clinical need for new drugs capable of prolonging survival either by increasing long-term remission rates and/or duration as first-line treatment or to improve on outcomes of second-line treatment. Strategies currently being exploited in clinical trials include attempts to deliver more killing selectively to tumours (e.g., intraperitoneal administration of cisplatin or radiolabelled monoclonal antibodies), agents designed to target drug resistance mechanisms (e.g., TLK-286 activated by glutathione transferase), agents targeting proteins/receptors shown to be selectively expressed in the disease (e.g., monoclonal antibodies recognising CA-125 or HER1; small molecules targeting HER1 such as gefitinib) and disrupting established tumour vasculature (e.g., 5,6-dimethyl xanthenone 4-acetic acid). At the pre-clinical level, agents being developed to target the phosphatidylinositol 3 kinase/AKT/mTOR pathway, and K-Ras inhibitors, may offer efficacy in the future.

Istradefylline, a novel adenosine A2A receptor antagonist, for the treatment of Parkinson's disease

Dopamine replacement therapy effectively treats the early motor symptoms of Parkinson's disease (PD). However, its association with the development of motor complications limits its usefulness in late stages of the disease. Adenosine A(2A) receptors are localised to the indirect striatal output function and control motor behaviour. They are active in predictive experimental models of PD and appear to be promising as the first major non-dopaminergic therapy for PD. Istradefylline is a novel adenosine A(2A) receptor antagonist currently in Phase III clinical trials for efficacy in patients with PD; results from Phase II clinical trials demonstrated that it provides a clinically meaningful reduction in 'off' time and an increased 'on' time with non-troublesome dyskinesia in levodopa-treated patients with established motor complications, and is safe and well tolerated.

Treatment strategies for acromegaly

Acromegaly is a chronic debilitating disorder caused by a growth hormone (GH)-producing pituitary adenoma. Active acromegaly is associated with a two- to fourfold increased mortality risk, mainly from cardiovascular disease. Transsphenoidal surgery is considered as the treatment of choice because of the rapidity of cure and normalisation of survival. Secondary treatment modalities are radiotherapy and medical treatment, and are important because surgery in the best hands cures only approximately 60% in long-term studies. Medical treatment with slow-release formulations of somatostatin are now widely used, also as primary treatment, and appear to be safe and effective in 50-60% of the patients. However, no data on mortality risk with these drugs is available. Recently, a GH-receptor blocking agent, pegvisomant, was licensed for use in acromegaly and appears to normalise IGF-1 in almost all patients. This article examines the pathophysiology of acromegaly, currently used medicines and their safety and efficacy, and the new drugs that are in development.

Current and future pharmacological intervention for diabetic retinopathy

Diabetic retinopathy (DR) is a potentially visually devastating complication of chronic hyperglycaemia. Prospective, randomised clinical trials have delineated the standard prevention protocols, including intensive glycaemic, blood pressure, and lipid control, and laser photocoagulation treatment for neovascularisation and clinically significant macular oedema. However, despite these interventions, vision loss from DR still occurs at an alarming rate. Researchers have directed their efforts towards better understanding the specific biological and chemical changes occurring in DR to develop more targeted pharmacological prevention and treatment strategies. This review of diabetic retinopathy will primarily detail the therapies in development at present, including aldose reductase inhibitors, advanced glycosylation end product inhibitors, antioxidants, supplemental oxygen, growth factor modulators including vascular endothelial growth factor inhibitors and protein kinase C inhibitors, extracellular matrix modifiers including corticosteroids, and vitreous modulators. The experimental therapies alter several different pathways that lead to DR. Future research will further delineate these pathways, and therapy is likely to involve arresting several different promoters of DR.

Emerging therapies in multiple sclerosis

Multiple sclerosis (MS) is the most common neurological cause of disability in young people. The disease-modifying treatments, IFN-beta and glatiramer acetate, have been widely available over the last decade and have shown a beneficial effect on relapse rate and magnetic resonance imaging parameters of disease activity; however, their effect on disease progression and disability is modest. Therefore, the search for alternative treatment strategies continues. As understanding of the heterogeneous pathophysiology of MS has increased, emphasis has shifted to more selective therapy that targets components of the inflammatory cascade and the promotion of remyelination and neuroprotection. These agents target the blood-brain barrier, systemic immune dysfunction, local inflammation and neurodegeneration. Combination therapies are being investigated for patients who fail first-line treatments. Many new drugs are being developed and tested that address these issues with the aim of finding a more effective and convenient therapy. These include humanized monoclonal antibodies such as daclizumab (IL-2 antagonist), oral immunomodulators such as sirolimus and statins and neuroprotective agents such as NMDA antagonists and Na+-channel blockers. Many of the treatments discussed in this review are still at early stages of development, but provide exciting potential treatment options; others have proved disappointing in larger extended-phase studies.

Peroxisome proliferator-activated receptor-gamma ligands for the treatment of breast cancer

Pioglitazone and rosiglitazone are thiazolidinediones used for the treatment of Type 2 diabetes mellitus. They modulate glucose and fat metabolism, mainly by binding to the nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR)-gamma. PPAR-gamma signalling is involved in a number of other disease conditions including cancer. In breast cancer cells, PPAR-gamma ligands inhibit proliferation and induce apoptosis both in vitro and in vivo. PPAR-gamma ligands also inhibit tumour angiogenesis and invasion. The only published clinical trial using a PPAR-gamma ligand in patients with metastatic breast cancer failed to show any clinical benefits. The mechanism of action of the thiazolidinediones in breast cancer cells is not fully understood but involves interactions with other nuclear hormone receptors, transcriptional co-activators and repressors as well as PPAR-gamma-independent effects. A better understanding of these mechanisms will be needed before PPAR-gamma ligands may be useful in the treatment of breast cancer patients.

Emerging drugs in cutaneous T-cell lymphomas

Cutaneous T-cell lymphomas are a heterogeneous group of rare lympho-proliferative disorders. In most cases, they are characterised by the accumulation of clonal CD4+ lymphocytes in the skin. Extracutaneous involvement is present in late stages only. Unfortunately, only few drugs are registered for these disfiguring diseases. Skin-directed therapies using topical formulations are the preferred first-line modalities for cutaneous lesions in early stages. In this field there are interesting developments using topical retinoids and gene therapy products, such as adeno-IFN-gamma. Systemic treatment uses biologicals, such as fusion molecules, monoclonal antibodies and immune response modifiers (IFNs, retinoids), and well-tolerated antiproliferative drugs, such as histone deacetylase inhibitors or liposomal doxorubicin.

TGF-beta inhibitors for the treatment of cancer

Advances in understanding the role of transforming growth factor (TGF)-beta in tumorigenesis have led to the development of TGF-beta inhibitors for cancer treatment. Three platforms of TGF-beta inhibitors have evolved: antisense oligonucleotides, monoclonal antibodies and small molecules. In this review, the current stage of development of each known TGF-beta inhibitor will be discussed. As part of the risk/benefit assessment of TGF-beta inhibitors, the known effects of TGF-beta deficiency in mice, non-clinical toxicology studies with TGF-beta inhibitors in rats, and the clinical studies with monoclonal antibodies against TGF-beta will be summarised.

Beyond 5-fluorouracil: new horizons in systemic therapy for advanced colorectal cancer

Worldwide, colorectal cancer is a common cancer and a major cause of morbidity and mortality. Patients frequently present with, or later develop, metastatic disease. Median survival with supportive care alone is approximately 6 - 8 months. However, a number of recent developments have greatly increased the range of therapeutic options, improving median survival to > 20 months. Cytotoxic agents such as capecitabine, irinotecan and oxaliplatin are now established treatment strategies. In parallel, an improved understanding of tumour biology has led to the development of non-cytotoxic targeted therapies. Examples include bevacizumab (targeting tumour angiogenesis) and cetuximab (targeting the epidermal growth factor receptor). These agents have recently been incorporated into standard management. This paper reviews these and other advances in the care of patients with advanced colorectal cancer and discusses a number of agents that are currently under development.