Everolimus for the treatment of pancreatic neuroendocrine tumors

Introduction: Pancreatic neuroendocrine tumors (PNET) represent the second most common primary malignancy of the pancreas. Until recently, therapeutic options for advanced PNET have been limited.

Areas covered: A recently published Phase III clinical trial demonstrated striking therapeutic activity of the mTOR inhibitor everolimus in advanced PNET and led to its approval for this indication by the FDA. This review discusses this landmark discovery in the context of currently available therapeutic options, pathophysiology and molecular genetics of PNET.

Expert opinion: The approval of everolimus for the treatment of PNET marks a major step forward in the clinical management of this disease and represents a notable example of the successful translation of a targeted therapy that was initially developed based on findings at the lab bench, into everyday clinical practice. These results encourage hopes that the overall therapeutic efficacy of such approaches can be further enhanced by the introduction of combinatorial regimens, simultaneously targeting more than one oncogenic signaling pathway, as well as by stratification of patients based on the individual genetic setup of their tumors.     

Lanreotide for the treatment of gastroenteropancreatic neuroendocrine tumors

Introduction: The prevalence of gastropancreatic neuroendocrine tumors (GEP-NETs), a largely sporadically occurring group of neoplasms, has rapidly increased. NET diagnoses often occur late and entail treatment challenges; treatment beyond surgical resection is typically required. Somatostatin analogs (SSAs), the cornerstone of GEP-NET therapy, target somatostatin receptors on NET cell surfaces and can ameliorate NET-related symptoms and prevent tumor progression.

Areas covered: This expert review summarizes the development of the SSA lanreotide and its role in treating NETs. Key lanreotide preclinical and clinical findings in acromegaly, carcinoid syndrome, and NETs are discussed, along with future treatment goals and therapeutic prospects.

Expert opinion: The role of SSAs in NET treatment was historically one of symptom management. Although this is a critical therapeutic component, ideal treatment would include prevention of tumor progression. As GEP-NETs are biologically diverse, progression prevention can be difficult, depending on primary tumor site and functional status. Recent data indicate that lanreotide significantly prolonged progression-free survival in metastatic GEP-NET patients. Practice patterns seem to be shifting toward using SSAs as first-line therapy. Response to SSAs has typically been categorized as either symptomatic or biochemical. However, SSA use to prevent tumor progression will lead to a new, objective response category based on tumor growth.     

Current treatment options for neuroendocrine tumors

Neuroendocrine tumors are heterogeneous in their clinical behavior and require therapies specially tailored according to staging and grading, origin and expression of peptide receptors. Somatostatin analogues act as antisecretory and antiproliferative agents. Chemotherapy is mandatory for poorly differentiated neuroendocrine carcinomas and is also effective in neuroendocrine tumors of the pancreas and of the bronchial system. For localized neuroendocrine tumors, surgery should be performed with curative intent and is also an option in advanced or metastasized neuroendocrine tumors with the goal to debulk tumor masses. Local ablative therapies may be applied to decrease tumor load in the liver; however, results are often of short duration. Peptide receptor radiotherapy is a new treatment method applying radionuclide-targeted somatostatin receptor agonists for internal cytotoxic radiotherapy in somatostatin receptor-expressing neuroendocrine tumors. Retrospective and prospective clinical studies indicate prolonged progression-free survival and overall survival of patients responding by stable disease or any kind of remission with this innovative treatment, which is, however, available only in a few specialized centers. Finally, small-molecule inhibitors of vascular endothelial growth factor and serine/threonine-protein kinase mTOR pathways have been shown to delay progression in patients with neuroendocrine tumors. In summary, treatment options for neuroendocrine tumors have expanded considerably in the last years leading to prolonged overall survival.     

Everolimus for the treatment of pancreatic neuroendocrine tumors

Introduction: Pancreatic neuroendocrine tumors (PNET) represent the second most common primary malignancy of the pancreas. Until recently, therapeutic options for advanced PNET have been limited. Areas covered: A recently published Phase III clinical trial demonstrated striking therapeutic activity of the mTOR inhibitor everolimus in advanced PNET and led to its approval for this indication by the FDA. This review discusses this landmark discovery in the context of currently available therapeutic options, pathophysiology and molecular genetics of PNET. Expert opinion: The approval of everolimus for the treatment of PNET marks a major step forward in the clinical management of this disease and represents a notable example of the successful translation of a targeted therapy that was initially developed based on findings at the lab bench, into everyday clinical practice. These results encourage hopes that the overall therapeutic efficacy of such approaches can be further enhanced by the introduction of combinatorial regimens, simultaneously targeting more than one oncogenic signaling pathway, as well as by stratification of patients based on the individual genetic setup of their tumors.     

Novel targets for the treatment of atherosclerosis

Atherosclerosis remains the leading cause of death in developed countries and thus demands the development of safe therapeutic treatments. Novel risk factors, in addition to the traditional targets, are being assessed. The significance of inflammation in atherosclerotic plaque development has become indisputable. A large number of published studies support the fact that investigations of the inflammatory aspects of atherosclerosis will be the target for future development. The C-reactive protein in particular has drawn specific attention due to its role as an inflammatory marker of atherosclerosis. Novel targets for atherosclerotic intervention include inhibitors of cholesterol synthesis and absorption such as acyl-coenzyme A:cholesterol acyltransferase, acyl-coenzyme A:diacylglycerol acyltransferase and cholesteryl ester transfer protein inhibitors, potential novel antioxidants other than anti-inflammatory peroxisome proliferator activated receptor agonists, and apolipoprotein A-I mimetic peptides.     

Novel targets for the treatment of endometriosis

Endometriosis is an enigmatic, debilitating disease that affects up to 15% of all women of reproductive age. It is characterised by pelvic pain and infertility. Current treatment regimens control the disease by inducing a hypoestrogenic state. Although the absence of circulating oestrogen levels leads to a regression of the disease, this hypoestrogenism also induces many unpleasant side effects. As such, these and other shortcomings of current drug therapies emphasise their limitations and the necessity for the development of novel endometriosis treatments. In this review, current therapies for medical management of endometriosis are discussed, as are their shortcomings. Potential target areas that may be attractive alternatives to current therapies are also reviewed. Emphasis is placed upon the emerging research using TNF inhibitors, their potential benefits over current treatment regimens and the development of future potential therapeutic targets.     

Novel targets for the treatment of endometriosis

Endometriosis is an enigmatic, debilitating disease that affects up to 15% of all women of reproductive age. It is characterised by pelvic pain and infertility. Current treatment regimens control the disease by inducing a hypoestrogenic state. Although the absence of circulating oestrogen levels leads to a regression of the disease, this hypoestrogenism also induces many unpleasant side effects. As such, these and other shortcomings of current drug therapies emphasise their limitations and the necessity for the development of novel endometriosis treatments. In this review, current therapies for medical management of endometriosis are discussed, as are their shortcomings. Potential target areas that may be attractive alternatives to current therapies are also reviewed. Emphasis is placed upon the emerging research using TNF inhibitors, their potential benefits over current treatment regimens and the development of future potential therapeutic targets.     

Therapy innovation for the treatment of pancreatic neuroendocrine tumors

INTRODUCTION: Traditional therapeutic approaches for patients with advanced neuroendocrine tumors (NETs) have included treatment with somatostatin analogs, hepatic-directed therapies, interferon and cytotoxic chemotherapy. Current knowledge about biological behavior of pancreatic neuroendocrine tumors (pNETs) has increased in the last decade, and some studies have been conducted to translate in the clinical setting. Among several molecular agents investigated in patients with progressive pNETs, everolimus and sunitinib have been studied in large Phase III trials. Both have produced significant benefit, with improvement in progression-free survival. These results were published last year by NEJM and were updated at the ASCO Annual Meeting in June 2011. AREAS COVERED: This review focuses on the potential molecular targets in pancreatic NETs in the light of recent advances. Furthermore, it summarizes the available data for targeted agents from Phase II and III trials open to patients with this tumor. EXPERT OPINION: These new agents are likely to play an increasingly important role in the future management of advanced pNETs. Their use in earlier phases of the disease could improve clinical outcome, avoiding side effects of the more toxic chemotherapy. The challenge in medical treatment of pNET is to define the patients who can benefit from this innovative therapy; future research should be directed to find predictive markers for response to the targeted agent.     

Novel therapeutics and targets for the treatment of diabetes

The microvascular complications of insufficiently controlled diabetes (neuropathy, retinopathy and nephropathy) and the marked increased risk of macrovascular events (e.g., stroke and myocardial infarction) have a dire impact on society in both human and economic terms. In Type 1 diabetes total β-cell loss occurs. In Type 2 diabetes, partial β-cell loss occurs before diagnosis, and the progressive β-cell loss during the life of the patient increases the severity of the disease. In patients with diabetes, increased insulin resistance in the muscle and liver are key pathophysiologic defects. In addition, defects in metabolic processes in the fat, GI tract, brain, pancreatic α-cells and kidney are detrimental to the overall health of the patient. This review addresses novel therapies for these deficiencies in clinical and preclinical evaluation, emphasizing their potential to address glucose homeostasis, β-cell mass and function, and the comorbidities of cardiovascular disease and obesity.     

Novel therapeutics and targets for the treatment of diabetes

The microvascular complications of insufficiently controlled diabetes (neuropathy, retinopathy and nephropathy) and the marked increased risk of macrovascular events (e.g., stroke and myocardial infarction) have a dire impact on society in both human and economic terms. In Type 1 diabetes total β-cell loss occurs. In Type 2 diabetes, partial β-cell loss occurs before diagnosis, and the progressive β-cell loss during the life of the patient increases the severity of the disease. In patients with diabetes, increased insulin resistance in the muscle and liver are key pathophysiologic defects. In addition, defects in metabolic processes in the fat, GI tract, brain, pancreatic α-cells and kidney are detrimental to the overall health of the patient. This review addresses novel therapies for these deficiencies in clinical and preclinical evaluation, emphasizing their potential to address glucose homeostasis, β-cell mass and function, and the comorbidities of cardiovascular disease and obesity.     

Novel therapeutic targets for the treatment of Fabry disease

Fabry disease is an X-linked lysosomal storage disorder resulting from deficient activity of α-galactosidase A. The traditional concept that is used to explain the complications of the disease involves progressive accumulation of globotriaosylceramide in endothelial and smooth muscle cells, resulting in vascular damage. Clinically, progressive renal insufficiency, cardiac involvement and brain pathology evolves. Two pharmaceutical companies have developed enzyme replacement therapy in Fabry disease. Although the first clinical trials showed great promise, it is clear that long-term effects are not as robust as was anticipated. Stabilisation of renal function and decreases in cardiac hypertrophy has been observed, but some patients may experience progressive complications. As there are recent indications that serum components contribute to the pathophysiology of Fabry disease, fundamental studies are needed to unravel the precise role and identity of these factors. Combination of these basic studies with clinical follow up may ultimately reveal when the ‘point of no return’ is reached. Advanced renal insufficiency seems to be a clinical indicator of lack of response, but other signs and symptoms are probably related to adverse outcome. It is anticipated that in the future controlled studies in early symptomatic or presymptomatic patients will be required. In addition, alternative strategies such as substrate reduction or chaperone therapy, either alone or in combination with enzyme replacement therapy, should be explored. Because Fabry disease is rare, collaborative efforts should be undertaken and openness of data should be strived for.     

Novel therapeutic targets for the treatment of heart failure

Despite considerable therapeutic advances, heart failure remains a medical and socioeconomic problem. Thus, there is a compelling need for new drugs that could improve clinical outcomes. In recent years, new potential therapeutic targets that are involved in the pathogenesis of heart failure have been identified, and new drugs are currently under investigation. A repeated finding is that the positive results that have been observed in preclinical studies and Phase II trials are not always confirmed in Phase III studies. This Review analyses the new therapeutic targets (for example, ventricular remodelling, renin-angiotensin-aldosterone system activation, defects in Ca(2+) cycling, and so on), the mechanism of action, efficacy and future perspectives of new drugs that are currently under development for the treatment of heart failure, and the possible explanations for the discrepancy between Phase II and Phase III trials.     

Novel therapeutic targets for the treatment of Fabry disease

Fabry disease is an X-linked lysosomal storage disorder resulting from deficient activity of alpha-galactosidase A. The traditional concept that is used to explain the complications of the disease involves progressive accumulation of globotriaosylceramide in endothelial and smooth muscle cells, resulting in vascular damage. Clinically, progressive renal insufficiency, cardiac involvement and brain pathology evolves. Two pharmaceutical companies have developed enzyme replacement therapy in Fabry disease. Although the first clinical trials showed great promise, it is clear that long-term effects are not as robust as was anticipated. Stabilisation of renal function and decreases in cardiac hypertrophy has been observed, but some patients may experience progressive complications. As there are recent indications that serum components contribute to the pathophysiology of Fabry disease, fundamental studies are needed to unravel the precise role and identity of these factors. Combination of these basic studies with clinical follow up may ultimately reveal when the 'point of no return' is reached. Advanced renal insufficiency seems to be a clinical indicator of lack of response, but other signs and symptoms are probably related to adverse outcome. It is anticipated that in the future controlled studies in early symptomatic or presymptomatic patients will be required. In addition, alternative strategies such as substrate reduction or chaperone therapy, either alone or in combination with enzyme replacement therapy, should be explored. Because Fabry disease is rare, collaborative efforts should be undertaken and openness of data should be strived for.     

Novel pharmacological targets for the treatment of Parkinson's disease

Dopamine deficiency, caused by the degeneration of nigrostriatal dopaminergic neurons, is the cause of the major clinical motor symptoms of Parkinson's disease. These symptoms can be treated successfully with a range of drugs that include levodopa, inhibitors of the enzymatic breakdown of levodopa and dopamine agonists delivered by oral, subcutaneous, transcutaneous, intravenous or intra-duodenal routes. However, Parkinson's disease involves degeneration of non-dopaminergic neurons and the treatment of the resulting predominantly non-motor features remains a challenge. This review describes the important recent advances that underlie the development of novel dopaminergic and non-dopaminergic drugs for Parkinson's disease, and also for the motor complications that arise from the use of existing therapies.     

Emerging therapies for the treatment of patients with advanced neuroendocrine tumors

Patients with neuroendocrine tumors may pursue a number of treatment options, but there is little consensus on a single, standard treatment approach. Somatostatin analogs are generally administered to patients with symptoms of hormonal secretion, and are often highly effective in this regard. However, the administration of somatostatin analogs is only rarely associated with tumor regression, and randomized trials demonstrating a survival benefit associated with their use have not been performed. Selected patients with hepatic metastases may undergo surgical debulking, embolization or other ablative therapies. The clinical benefit associated with administration of systemic agents such as IFN-α or cytotoxic chemotherapy has been limited. With the possible exception of streptozocin-based therapy in patients with pancreatic neuroendocrine tumors, the widespread use of standard cytotoxic regimens has been limited by their relatively modest antitumor activity, as well as concerns regarding their potential toxicity. The modest efficacy seen with these agents in patients with advanced neuroendocrine tumors has led to great interest in the development of novel treatment approaches. One such approach is the use of radiolabeled somatostatin analogs. Recently, agents targeting the VEGF pathway and mammalian target of rapamycin have also shown promise in patients with advanced neuroendocrine tumors. Ongoing randomized studies should help better define the role these agents will play in the future treatment of patients with this disease.     

Emerging therapies for the treatment of patients with advanced neuroendocrine tumors

Patients with neuroendocrine tumors may pursue a number of treatment options, but there is little consensus on a single, standard treatment approach. Somatostatin analogs are generally administered to patients with symptoms of hormonal secretion, and are often highly effective in this regard. However, the administration of somatostatin analogs is only rarely associated with tumor regression, and randomized trials demonstrating a survival benefit associated with their use have not been performed. Selected patients with hepatic metastases may undergo surgical debulking, embolization or other ablative therapies. The clinical benefit associated with administration of systemic agents such as IFN-alpha or cytotoxic chemotherapy has been limited. With the possible exception of streptozocin-based therapy in patients with pancreatic neuroendocrine tumors, the widespread use of standard cytotoxic regimens has been limited by their relatively modest antitumor activity, as well as concerns regarding their potential toxicity. The modest efficacy seen with these agents in patients with advanced neuroendocrine tumors has led to great interest in the development of novel treatment approaches. One such approach is the use of radiolabeled somatostatin analogs. Recently, agents targeting the VEGF pathway and mammalian target of rapamycin have also shown promise in patients with advanced neuroendocrine tumors. Ongoing randomized studies should help better define the role these agents will play in the future treatment of patients with this disease.     

Molecular targets for the treatment of testicular germ cell tumors

In the last decade novel therapeutic approaches for the treatment of cancer have been proposed: inhibitors of serine/threonine and tyrosine kinases, angiogenesis inhibitors, gene therapy approaches and others. In some cases the clinical trials have confirmed the efficacy of these approaches. Here, we will review the discovered molecular targets for the treatment of testicular germ cell tumors.     

Emerging therapeutic targets for the treatment of malignant rhabdoid tumors

Introduction: Malignant Rhabdoid Tumor (MRT) is a rare and highly aggressive malignancy primarily affecting infants and young children. The most common anatomic locations are the central nervous system (AT/RT), the kidneys (RTK) and other soft tissues (eMRT). The genetic origin of this disease is linked to mutations in SMARCB1, a gene encoding a core subunit of the SWI/SNF chromatin-remodeling complex.

Areas covered: Conventional multimodal treatment may offer a significant survival benefit to certain patients. It remains to be determined, however, which patients will prove resistant to chemotherapy and need novel therapeutic approaches. Herein we discuss key signal transduction pathways involved in the pathogenesis of rhabdoid tumors for potential targeted therapy (EZH2, DNMT, HDAC, CDK4/6/Cyclin D1/Rb, AURKA, SHH/GLI1, Wnt/ß-Catenin, immunotherapy). Additional agents currently evaluated in preclinical settings and experimental clinical trials are discussed.

Expert opinion: MRTs are genetically homogeneous, but epigenetically distinct malignancies. While there is an abundance of experimental in vitro studies evaluating potential therapeutic avenues, a dearth of clinical trials specifically for this entity persists. In order to improve outcome patients need to be carefully stratified and treated by targeted therapies combined with conventional chemotherapy or with new, less selective experimental agents in phase I/II clinical trials.     

Novel mechanistic targets for the treatment of sub-acute and chronic bronchitis

Sub-acute and chronic bronchitis (SACB) are among the least well studied major medical problems that exist today. While much research and novel drug discovery have focused on asthma, comparatively little has been performed on chronic bronchitis, the fourth or fifth most frequent disease (4 to 6% of the population over 45 years of age), or on sub-acute bronchitis, the persistent symptoms of a respiratory infection which is the major reason Americans visit a physician (20%). This lack of attention is largely due to difficulties associated with modeling the pathophysiology of SACB in vitro, in situ, in organs or in animals as well as the presumption that drugs developed for asthma would also be effective in SACB. Data with bronchodilators (anti-cholinergics versus beta2-adrenergic agonist) and corticosteroids have strongly dismissed that premise. In this review of potential novel mechanistic targets directed specifically at SACB, an emphasis is given to recent data, gathered most convincingly from tissues and patients with cystic fibrosis, that have led to an appreciation of the critical role respiratory epithelial dysfunction plays in the pathophysiology and symptoms of these diseases. Mechanistic targets that restore (normalize or accelerate) airway 'cleansing' (enhance host defense) by accelerating mucociliary clearance are described and given preference over anti-inflammatory mechanisms that could further impair host defense.