Prevention and treatment of diabetic retinopathy: evidence from clinical trials and perspectives

Diabetic retinopathy is the most common microvascular complication of diabetes mellitus and is the leading cause of blindness amongst working-age adults in Western countries. Large observational and randomized studies have consistently shown that optimal blood glucose and blood pressure control is the key component of intervention strategies aimed to halt or regress the disease, and limit the risk of progression to the proliferative stage, with consequent visual loss up to blindness in most severe cases. Amelioration of dyslipidemia by statins, especially if combined with fenofibrate, may also ameliorate retinopathy in line with a potential pathogenic role of hyperlipidemia. Recently, evidence has also emerged that renin-angiotensin system (RAS) inhibitors may electively prevent or delay progression of retinopathy, possibly because of specific protective effect against the structural and functional retinal changes sustained by local RAS activation. Thus, metabolic and blood pressure control by RAS inhibition is to prevent or limit the onset of retinopathy and its progression towards visual-threatening stages. Topic treatment with anti-vascular endothelial growth factor (VEGF) agents is emerging as a treatment option for retinopathy in advanced stages to limit the need for laser photocoagulation. This option however should be considered with caution due to the risk of systemic adverse events.

Drug delivery trends in clinical trials and translational medicine: evaluation of pharmacokinetic properties in special populations

In spite of the recent advances in technology to optimize the absorption, distribution, metabolism and elimination (ADME) properties of new and promising medicinal products to reduce clinical failures, the investigation of drug disposition in the pediatric and elderly populations continues to be under evaluated. With the increasing prevalence of aging populations world-wide, there is a growing concern from health care providers, regulators and the general public that drug delivery is still less than optimal for the vulnerable patient populations likely to be more sensitive to adverse effects of the new investigational drugs. This review of the ClinicalTrials.gov database revealed a rapidly increasing number of clinical trials and a trend towards wider inclusion criteria of the elderly population in clinical trials over the past 10 years. However, when we summarized trials by drug delivery, biological platforms, and disease categories, less than 10% of these trials included pharmacokinetic evaluation in elderly subjects greater than 65 years of age, and less than 4% included pharmacokinetic evaluation in children less than 17 years of age. Across the various disease areas, the percentage of trials that included pharmacokinetic evaluation in the children and elderly has remained low and is consistently less than the studies that included the younger 18 to 65 age group. Therefore, it is not known whether the right information is being generated from the growing number of clinical trials to guide optimal dosing recommendations in special patient populations.

Peripheral nerve stimulation for chronic neurogenic pain

Peripheral nerve stimulation (PNS) has been used for the treatment of neuropathic pain for more than 40 years. Recent interest in the utilization of this technique stems from the many modifications of the original procedure and the refinement of the available hardware. This rendered the procedure less traumatic and more effective, and thus more widely accepted as a neuromodulation technique for the treatment of various chronic pain syndromes including post-traumatic and postsurgical neuropathy, occipital neuralgia, and complex regional pain syndromes, and in relatively new indications for neuromodulation, such as migraines and daily headaches, cluster headaches. We present a review of the principle and indications for the use of PNS, and review our single institution experience that comprises 24 peripheral nerve stimulators as well as 8 occipital nerve stimulators over 13 years. We review the protocol of our approach including the surgical nuances for our implantation technique. Collaborative efforts in future research will lead to a growth in our clinical experience with the utilization of PNS and will help in identifying the best candidates for it. This, along with the development and refinement of the available hardware would lead to a more specific patient selection for each modality of treatment, increasing the efficacy and success of the intended treatment.

Occipital nerve stimulation: technical and surgical aspects of implantation

Occipital nerve stimulation may provide pain relief for patients with otherwise refractory primary headache disorders. While this treatment modality remains an off-label use of spinal cord stimulator technology, a growing body of literature documents surgical techniques, stimulation parameters, complications, and outcome of this novel form of neuromodulation. This chapter will review occipital nerve stimulation, including surgical techniques and complications noted in the literature. A discussion of stimulation parameters used for occipital stimulation will be included. Prospective, blinded studies of occipital nerve stimulation may clarify the role of occipital stimulation in chronic headache management.

Peripheral nerve stimulation for fibromyalgia

Fibromyalgia is a condition marked by widespread chronic pain, accompanied by a variety of other symptoms, including sleep and fatigue disorders, headaches, disorders of the autonomic nervous system, as well as cognitive and psychiatric symptoms. It occurs predominantly in women and is often associated with other systemic or autoimmune diseases. Despite its serious socio economical burden, the treatment options remain poor. In this chapter, the authors discuss the possibilities of using greater occipital nerve stimulation as a treatment for fibromyalgia, based on available clinical studies. Greater occipital nerve stimulation has already been used successfully to treat occipital neuralgia and various primary headache syndromes. Testable hypothetical working mechanisms are proposed to explain the surprising effect of this treatment on widespread bodily pain.

Combination drug therapy for chronic pain: a call for more clinical studies

Chronic pain is a debilitating clinical condition associated with a variety of disease entities including diabetic neuropathy, postherpetic neuralgia, low back pathology, fibromyalgia, and neurological disorders. For many general practitioners and specialists, managing chronic pain has become a daunting challenge. As a modality of multidisciplinary chronic pain management, medications are often prescribed in combinations, an approach referred to as combination drug therapy (CDT). However, many medications for pain therapy, including antidepressants and opioid analgesics, have significant side effects that can compound when used in combination and impact the effectiveness of CDT. To date, clinical practice of CDT for chronic pain has been based largely on clinical experiences. In this article, we will focus on (1) the scientific basis and rationales for CDT, (2) current clinical data on CDT, and (3) the need for more clinical studies to establish a framework for the use of CDT.

PERSPECTIVE

More preclinical, clinical, and translational studies are needed to improve the efficacy of combination drug therapy that is an integral part of a comprehensive approach to the management of chronic pain.

Choosing a patient-reported outcome measure

There has been much philosophical interest regarding the 'hierarchy of evidence' used to determine which study designs are of most value for reporting on questions of effectiveness, prognosis, and so on. There has been much less philosophical interest in the choice of outcome measures with which the results of, say, an RCT or a cohort study are presented. In this paper, we examine the FDA's recently published guidelines for assessing the psychometric adequacy of patient-reported outcome measures. We focus on their recommendations for demonstrating content validity and also for how researchers should weigh up the sum of psychometric evidence when choosing these measures. We argue that questions regarding judgment and understanding meaning of these measures should play a more central role in determining their adequacy.

Post-HAART outcomes in pediatric populations: comparison of resource-limited and developed countries

CONTEXT

No formal comparison has been made between the pediatric post-highly active antiretroviral therapy (HAART) outcomes of resource-limited and developed countries.

OBJECTIVE

To systematically quantify and compare major baseline characteristics and clinical end points after HAART between resource-limited and developed settings.

METHODS

Published articles and abstracts (International AIDS Society 2009, Conference on Retroviruses and Opportunistic Infections 2010) were examined from inception (first available publication for each search engine) to March 2010. Publications that contained data on post-HAART mortality, weight-for-age z score (WAZ), CD4 count, or viral load (VL) changes in pediatric populations were reviewed. Selected studies met the following criteria: (1) patients were younger than 21 years; (2) HAART was given (≥ 3 antiretroviral medications); and (3) there were >20 patients. Data were extracted for baseline age, CD4 count, VL, WAZ, and mortality, CD4 and virologic suppression over time. Studies were categorized as having been performed in a resource-limited country (RLC) or developed country (DC) on the basis of the United Nations designation. Mean percentage of deaths per cohort and deaths per 100 child-years, baseline CD4 count, VL, WAZ, and age were calculated for RLCs and DCs and compared by using independent samples t tests.

RESULTS

Forty RLC and 28 DC publications were selected (N = 17 875 RLCs; N = 1835 DC). Mean percentage of deaths per cohort and mean deaths per 100 child-years after HAART were significantly higher in RLCs than DCs (7.6 vs 1.6, P < .001, and 8.0 vs 0.9, P < .001, respectively). Mean baseline CD4% was 12% in RLCs and 23% in DCs (P = .01). Mean baseline VLs were 5.5 vs 4.7 log(10) copies per mL in RLCs versus DCs (P < .001).

CONCLUSIONS

Baseline CD4% and VL differ markedly between DCs and RLCs, as does mortality after pediatric HAART. Earlier diagnosis and treatment of pediatric HIV in RLCs would be expected to result in better HAART outcomes.

Statistical decisions and the interim analyses of clinical trials

This paper analyzes statistical decisions during the interim analyses of clinical trials. After some general remarks about the ethical and scientific demands of clinical trials, I introduce the notion of a hard-case clinical trial, explain the basic idea behind it, and provide a real example involving the interim analyses of zidovudine in asymptomatic HIV-infected patients. The example leads me to propose a decision analytic framework for handling ethical conflicts that might arise during the monitoring of hard-case clinical trials. I use computer simulations to show how the framework can assist in reconciling certain ethical conflicts. The framework is partial, lacking the precision of a complete systematization of statistical monitoring procedures in practice.

Structure, function and pathophysiology of protease activated receptors

Discovered in the 1990s, protease activated receptors(1) (PARs) are membrane-spanning cell surface proteins that belong to the G protein coupled receptor (GPCR) family. A defining feature of these receptors is their irreversible activation by proteases; mainly serine. Proteolytic agonists remove the PAR extracellular amino terminal pro-domain to expose a new amino terminus, or tethered ligand, that binds intramolecularly to induce intracellular signal transduction via a number of molecular pathways that regulate a variety of cellular responses. By these mechanisms PARs function as cell surface sensors of extracellular and cell surface associated proteases, contributing extensively to regulation of homeostasis, as well as to dysfunctional responses required for progression of a number of diseases. This review examines common and distinguishing structural features of PARs, mechanisms of receptor activation, trafficking and signal termination, and discusses the physiological and pathological roles of these receptors and emerging approaches for modulating PAR-mediated signaling in disease.

The Clinical Trials Transformation Initiative (CTTI)

The Clinical Trials Transformation Initiative (CTTI) is a public-private partnership created in 2007 between the United States Food and Drug Administration (FDA) and Duke University for the purpose of identifying practices that will increase the quality and efficiency of clinical trials. The initiative was generated from the realization that the clinical trials system in the United States has been suffering as a result of increasingly longer study start-up times, slowing enrollment of patients into trials, increasing clinical trial costs, and declining investigator interest in participating in clinical trials. Although CTTI was created to address a crisis for US clinical research, it seeks to identify practice improvements that can be applied internationally, and is therefore engaging international collaborators with international efforts that have similar objectives. CTTI's approach is to involve all sectors in the selection, conduct, and interpretation of its projects; to keep the dialogue open across sectors; to provide evidence that can influence regulatory guidance, and to attempt to create a "level playing field" when recommending change. The hope is that a broad and diverse data-driven discussion of the important issues in clinical trials will lead to meaningful change for the benefit of all concerned, and importantly for patients.

Diabetes and biomarkers

Biomarkers play an integral part in conducting clinical trials and treating patients. In most instances, they help medical practitioners, researchers, and regulatory officials make well-informed, scientifically sound decisions. However, in clinical studies, there is often uncertainty in how much weight to place on biomarker results versus clinical outcomes. This uncertainty emanates from opposing goals of the drug approval process. On one hand, the process must ensure that all therapeutics tested are safe and that the benefits outweigh the risks. On the other hand, the process should allow therapies to be accessible to patients as quickly as reasonably possible. Judicious use of biomarkers in the drug development process can bring these goals into alignment. More efficient discovery and use of biomarkers in the development of antidiabetes drugs will depend on advancing our understanding of the pathogenesis of diabetes and especially its macrovascular complications.

The Sri Lanka Clinical Trials Registry--moving forward

The Sri Lanka Clinical Trials Registry (SLCTR) is a Primary Registry in the Registry Network of the World Health Organization's International Clinical Trials Registry Platform (WHO-ICTRP), and regularly feeds data to its Clinical Trials Search Portal. Over the last few years, the SLCTR has been able to achieve its original objective of providing a national trial register for Sri Lankan researchers, but its role has always been more than that of a mere storehouse of trial data. The research landscape is rapidly changing in Sri Lanka, and the SLCTR has been a key stimulus to a resurgent interest in clinical research among the Sri Lankan research community. The SLCTR is working together with its partner stakeholders to facilitate research in the country, and to ensure that clinical trials conducted in Sri Lanka meet the highest ethical and scientific standards.

The Karlsburg Diabetes Management System: translation from research to eHealth application

BACKGROUND

Several telemedicine-based eHealth programs exist, but patient-focused personalized decision support (PDS) is usually lacking. We evaluated the acceptance, efficiency, and cost-effectiveness of telemedicine-assisted PDS in routine outpatient diabetes care.

METHODS

Data are derived from the Diabetiva® program of the German health insurance company BKK TAUNUS. Diabetiva offers telemedicine-based outpatient health care in combination with PDS generated by the Karlsburg Diabetes Management System, KADIS®. This retrospective analysis is based on data from the first year of running KADIS-based PDS in routine diabetes care. Participants were insured persons diagnosed with diabetes and cardiovascular diseases. For final analysis, patients were grouped retrospectively as users or nonusers according to physician acceptance or not (based on questionnaires) of the KADIS-based PDS.

RESULTS

A total of 538 patients participated for more than one year in the Diabetiva program. Of these patients, 289 had complete data sets (two continuous glucose monitoring measurements, two or more hemoglobin A1c (HbA1c) values, and a signed questionnaire) and were included in the final data analysis. Of the physicians, 74% accepted KADIS-based PDS, a rate that was clearly related to HbA1c at the beginning of the observation. If KADIS-based PDS was accepted, HbA1c decreased by 0.4% (7.1% to 6.7%). In contrast, rejection of KADIS-based PDS resulted in an HbA1c increase of 0.5% (6.8% to 7.3%). The insurance company revealed an annual cost reduction of about 900 € per participant in the Diabetiva program.

CONCLUSIONS

KADIS-based PDS in combination with telemedicine has high potential to improve the outcome of routine outpatient diabetes care.

Clinical studies with traditional Chinese medicine in the past decade and future research and development

Traditional Chinese medicine (TCM) is currently considered a complementary or alternative medical system in most Western countries and has been increasingly accepted worldwide. More and more clinical trials on TCM have been conducted internationally, and scientists worldwide are becoming increasingly interested in the evaluation of clinical efficacy of TCM based on clinical trials. This paper reviews the situation of clinical trials on TCM in the past decade, including systematic reviews about clinical trials either focusing on the treatment of disease with TCM approaches or focusing on one herbal product, conduction of clinical trials on TCM either with randomization and controlled methods or general observation. Some general issues on the conduct of clinical trials on TCM, such as randomization, control, quality of life (QOL), patient reported outcomes (PROs) and biomarkers, quality control, safety evaluation and case studies, are discussed, and accordingly some suggestions are proposed.

Novel treatment modalities for nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is the most common cause of chronic liver disease in the Western world. It can lead to cirrhosis and hepatocellular cancer, and is independently associated with an increased risk of death due to cardiovascular and liver diseases. Over the past 5 years, numerous advances in understanding its pathogenesis have been made, providing a rationale for translation of this information into clinical trials. Although the optimum therapy is still awaited, there is strong evidence to support the use of vitamin E in selected subjects. Many other potential therapeutic options are now available. In this paper, we review the status of both current and emerging therapeutic strategies for patients with NASH.

Development of anti-cancer drugs

Every new anti-cancer drug or drug combination is evaluated for safety and efficacy before being approved. Clinical development of cytotoxic anticancer drugs classically follows three main phases. Phase I trials represent the first administration of a new drug or combination to human beings. Their primary goal is to determine the recommended phase two dose and also to collect toxicity, pharmacokinetic and pharmacodynamic data. Phase II trials are screening studies aimed at identifying signals of anti-tumor activity in a specific tumor type and setting. Phase III trials aim to compare the efficacy of a new treatment with standard of care and can lead to regulatory approval when positive. The recent emergence of molecularly targeted agents has challenged the traditional developmental pathway for anti-cancer drugs. Using biomarker enriched patient populations has been successful for a few agents. Otherwise, new types of trials have been proposed for these agents in an attempt to elucidate their mechanism of action, such as phase 0 trials and "window of opportunity" trials. These two types of trials and the classical three phase trials are discussed in detail.

Adipose-derived stem and stromal cells for cell-based therapy: current status of preclinical studies and clinical trials

The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift that may provide alternative therapeutic solutions for several diseases. The clinical use of either embryonic stem cells or induced pluripotent stem cells remains limited because of cell regulations, ethical considerations and the requirement for genetic manipulation, although these cells are theoretically highly beneficial. Adipose-derived stem cells (ASCs) appear to be an ideal population of stem cells for practical regenerative medicine, given that they are plentiful, of autologous tissue origin and thus non-immunogenic, and are more easily available because of minimal ethical considerations. Although ASCs originate from mesodermal lineages, recent preclinical studies have demonstrated that the use of ASCs in regenerative medicine is not limited to mesodermal tissue, but can also extend to both exodermal and endodermal tissues and organs. This review summarizes and discusses current preclinical and clinical data on the use of ASCs in regenerative medicine and discusses the future applications of such cell-based therapies.

The syndrome of inappropriate antidiuretic hormone: current and future management options

Hyponatraemia is the commonest electrolyte abnormality, and syndrome of inappropriate antidiuretic hormone (SIADH) is the most frequent underlying pathophysiology. Hyponatraemia is associated with significant morbidity and mortality, and as such appropriate treatment is essential. Treatment options for SIADH include fluid restriction, demeclocycline, urea, frusemide and saline infusion, all of which have their limitations. The introduction of the vasopressin-2 receptor antagonists has allowed clinicians to specifically target the underlying pathophysiology of SIADH. Initial studies have shown good efficacy and safety profiles in the treatment of mild to moderate hyponatraemia. However, studies assessing the efficacy and safety of these agents in acute severe symptomatic hyponatraemia are awaited. Furthermore, the cost of these agents at present may limit their use.

Integrating ADNI results into Alzheimer's disease drug development programs

The Alzheimer's Disease Neuroimaging Initiative (ADNI) is providing critical new information on biomarkers in cognitively normal elderly, persons with mild cognitive impairment (MCI), and patients with mild Alzheimer's disease (AD). The data provide insights into the progression of the pathology of AD over time, assist in understanding which biomarkers might be most useful in clinical trials, and facilitate development of disease-modifying treatments. ADNI results are intended to support new AD treatment development; this report considers how ADNI information can be integrated in AD drug development programs. Cerebrospinal fluid (CSF) amyloid beta protein (Abeta) measures can be used in Phase I studies to detect any short term effects on Abeta levels in the CSF. Phase II studies may benefit most from biomarker measures that can inform decisions about Phase III. CSF Abeta levels, CSF total tau and phospho-tau measures, fluorodeoxyglucose positron emission tomography (FDG PET), Pittsburgh Compound B (PIB) amyloid imaging, or magnetic resonance imaging (MRI) may be employed to select patients in enriched trials or as outcomes for specific disease-modifying interventions. Use of biomarkers may allow Phase II trials to be conducted more efficiently with smaller populations of patients or shorted treatment times. New drug applications (NDAs) may include biomarker outcomes of phase III trials. ADNI patients are highly educated and are nearly all of Caucasian ethnicity limiting the generalizability of the results to other populations commonly included in global clinical trials. ADNI has inspired or collaborates with biomarker investigations worldwide and together these studies will provide biomarker information that can reduce development times and costs, improve drug safety, optimize drug efficacy, and bring new treatments to patients with or at risk for AD.

Cetuximab in combination therapy: from bench to clinic

Cetuximab, a chimeric IgG(1) monoclonal antibody directed against the ligand-binding domain of the epidermal growth factor receptor, offers a paradigm for the combination of molecularly targeted therapies with cytotoxic agents. In preclinical models, the addition of cetuximab to chemotherapy or radiation therapy enhances antitumor activity. Proposed mechanisms include reducing tumor cell proliferation, angiogenesis, and DNA repair capacity; increasing apoptosis; and inducing cell cycle arrest at treatment-sensitive points. These effects may enhance and restore tumor sensitivity to cytotoxic therapies. In clinical trials, the addition of cetuximab to chemotherapy improves outcomes of patients who had previously failed such agents, as illustrated in irinotecan-resistant and oxaliplatin-refractory metastatic colorectal cancer. As initial therapy, the addition of cetuximab to chemotherapy extends survival in colorectal cancer, lung cancer, and head and neck cancer. Combining cetuximab with radiation therapy extends survival in locally advanced head and neck cancer. As predictive biomarkers are identified, it may become possible to select patients most likely to benefit from such combinations.

Clinical Medicine and Clinical Trials

The author discusses the role of clinical trials in clinical medicine.

Neuroendocrine tumors of the pancreas: what's new. Highlights from the "2010 ASCO Gastrointestinal Cancers Symposium". Orlando, FL, USA. January 22-24, 2010

Surgical excision has been the mainstay of treatment for neuroendocrine tumors of the pancreas (PNET). Compounds like streptozocin and dacarbazin have been traditionally used in inoperable cases and somatostatin to treat syndromes deriving from functional tumors. However, a lot of progress has taken place in the area of molecular characterization of these tumors, revealing activation of mammalian target of rapamycin (mTOR) and VEGF pathways. Recent data from the 2010 ASCO Gastrointestinal Cancers Symposium demonstrate antitumor activity of everolimus, an mTOR inhibitor in combination with temozolomide in a phase I/II trial and of sunitinib versus placebo in a randomized double blinded phase III trial. The role of modern biologic compounds in the treatment of PNET is not clear yet. In addition, combination of resection and transarterial chemoembolization (TACE) has been proven effective over either modality alone in the treatment of PNET metastatic to the liver in a retrospective analysis. This comes to address the problem of selecting local intervention in a metastatic disease, which has been a reasonable choice for this group of tumors in the past. Last but not least the role of Ki-67 in decision-making in PNET is being discussed.

Course of frequent/daily headache in the general population and in medical practice

Frequent headache is defined as headaches ≥ 15 days/month and daily headache operationally as headaches ≥ 5 days/week. In this article, we review the outcome of frequent/ daily headache in the general population and in medical practice. In the general population, within 1 year fewer than half of those with frequent/daily headache will still have frequent/daily headache, with a gradual further decrease over subsequent years. In medical practice, the results of studies suggest a one-third reduction in headache days/month over 6 to 12 months, with nearly 40% of patients with frequent/daily improving ≥ 50% in headache days/month over the same time period (50% responder rate). In terms of predictors of poor outcome, no clear picture emerges.

Recent development of molecular-targeted drugs in lung cancer

Numerous molecular target drugs have been introduced for the treatment of advanced malignancies. In the treatment of lung cancer, epidermoid growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) demonstrate striking antitumor activity in selected EGFR mutation positive patients. Patient selection by biomarker is extremely important to obtain successful results. The anti-vascular endothelial growth factor (VEGF) antibody, bevacizumab, shows a markedly increased response rate, progression free survival of advanced non-squamous cell lung cancer when combined with cytotoxic drugs. The classification of lung cancer is rapidly changing based on the advances in molecular biology. Here, the recent development of new molecular target drugs against lung cancer is thoroughly reviewed in addition to EGFR-TKIs and bevacizumab with special emphasis on the clinical application.

Clinical trials in traumatic brain injury: past experience and current developments

In this article, we review past and current experience in clinical trials of traumatic brain injuries (TBIs), we discuss limitations and challenges, and we summarize current directions. The focus is on severe and moderate TBIs. A systematic literature search of the years from 1980 to 2009 revealed 27 large phase III trials in TBI; we were aware of a further 6 unpublished trials. Analysis of these 33 trials yielded interesting observations: There was a peak incidence of trial initiations that occurred in the mid-1990s with a sharp decline during the period from 2000 to 2004. Most trials that reported a significant treatment effect were studies on a therapeutic strategy (e.g., decompressive craniectomy, hypothermia), and these were single-center studies. Increasingly, studies have been shifting toward the Far East. The currently existing trial registries permit insight into ongoing or recently conducted trials. Compared with the past decade, the number of studies on neuroprotective agents taken forward into efficacy-oriented studies is low. In contrast, the number of studies on therapeutic strategies appears to be increasing again. The disappointing results in trials on neuroprotective agents in TBI have led to a critical reappraisal of clinical trial methodology. This has resulted in recommendations for preclinical workup and has triggered extensive analysis on approaches to improve the design and analysis of clinical trials in TBI. An interagency initiative toward standardization on selection and coding of data elements across the broad spectrum of TBI is ongoing, and will facilitate comparison of research findings across studies and encourage high-quality meta-analysis of individual patient data in the future.