Current opinion in investigational drugs最新文献

One of the primary impediments to successful drug R&D is the frequent failure of successfully translating positive results obtained in animal models to human disease. To a large degree, this discrepancy is secondary to the substantial biological differences between species. Non-human primate models have the advantage of significant physiological, metabolic, biochemical and genetic similarity to humans. Despite this advantage, there has been a relative paucity of non-human primate models used in the study of disease states that currently underlie the most common causes of morbidity and mortality, such as chronic myocardial ischemia leading to heart failure. This review describes a primate model of heart failure that closely mimics the cardiomyopathic process observed in humans. The primary advantage of this non-human primate model is that, unlike existing heart failure models, it allows for continuous study during progressive stages of heart failure, including myocardial ischemia, progressive left ventricular remodeling and end-stage congestive heart failure. In addition to this model of heart failure, other non-human primate models for cardiovascular drug R&D are also reviewed.

Erythropoiesis stimulating agents (ESAs) are effective drugs that correct anemia in patients with chronic kidney disease (CKD). Recombinant human erythropoietin (EPO), the first ESA that became available more than 20 years ago, is similar to the naturally occurring molecule. In subsequent years, pharmacological research focused on the development of new agents with improved characteristics, with the creation of high molecular weight ESAs having been the first approach. In more recent years, new agents have been developed, including peginesatide (Hematide; Affymax Inc/Takeda Pharmaceutical Co Ltd), which is a dimeric peptide with a chemical structure unrelated to EPO that is being evaluated in phase III clinical trials. In addition, the clinical development of two inhibitors of hypoxia-inducible transcription factor has been resumed recently, while other approaches, such as gene therapy and EPO fusion proteins, and the inhibition of GATA and hematopoietic cell phosphatase remain far from being applicable in clinical practice. New iron compounds, which are becoming increasingly available, will facilitate an integrated approach to anemia management using both iron and/or ESAs, according to the clinical needs of patients. This review discusses new therapeutic options (already available or still under development) for the treatment of CKD-associated anemia, including ESAs and intravenous iron molecules.

Cardiovascular and cerebrovascular diseases share many pathophysiological traits, often impact one another and share several risk factors, though not always to the same magnitude. Therefore, it is not surprising that many classes of cardiovascular drugs have demonstrated effectiveness in the primary prevention, acute treatment and secondary prevention of stroke. Important advances have been made since 2007 in the use of antiplatelets, anticoagulants, antihypertensives, antiarrhythmics and statins for the treatment of stroke. This review summarizes selected clinical trials of cardiovascular drugs completed from 2007 to 2010 that generated important evidence supporting the efficacy of these drugs in stroke treatment. Ongoing trials and preclinical research of promising agents and treatment strategies are also discussed.

Despite being the most common arrhythmia currently treated by cardiologists, safe and effective treatments for atrial fibrillation (AF) remain elusive. To address this issue, Astellas Pharma Inc, Merck & Co Inc and Cardiome Pharma Corp are developing vernakalant (RSD-1235), a drug which dose-dependently inhibits sodium channels and several potassium repolarizing currents. Of particular note, vernakalant inhibits I(Kur) (K(v)1.5), a current that is more predominant in atrial than in ventricular tissue. Consistent with this observation, vernakalant produced increases in atrial refractory period with minimal actions on QTc interval or ventricular refractory period in both humans and animals. Intravenous vernakalant terminated recent-onset AF in several animal models, and also in patients with short-duration AF or AF following cardiac surgery enrolled in phase II and III clinical trials. Vernakalant was well tolerated and adverse reactions were transient and mild. Thus, vernakalant holds considerable promise for the treatment of recent-onset AF; however, given its relatively short half-life, continuous dosing may be required in order to maintain sinus rhythm following conversion from AF. The efficacy and safety of vernakalant for the long-term management of AF remains to be determined. Phase III clinical trials with intravenous vernakalant are ongoing, and phase II clinical trials are also being conducted with an oral formulation intended for chronic use.

Hyponatremia is the most prevalent electrolyte disorder in hospitalized patients. Vasopressin plays an important role in the pathogenesis of this disorder through its action on the vasopressin type 2 receptor (V(2)R), leading to electrolyte-free water reabsorption. Multiple vasopressin receptor antagonists have recently been developed that differ in their specificity for V(2)R and V(1)R. These agents have applications in diseases that can result in hypervolemic and euvolemic hyponatremia, such as the syndrome of inappropriate antidiuretic hormone secretion, congestive heart failure and cirrhosis. V(2)R antagonists have demonstrated promise in the short-term correction of hyponatremia, although the long-term survival benefits of these drugs are less clear. This review discusses the physiology of vasopressin in hyponatremia, the clinical implications of the disorder and examples of individual therapeutics used in treatment strategies.

The endothelial glycocalyx (EG) is an extracellular matrix (ECM) coating the luminal surface of the vascular endothelium. Hyaluronan (HA), a glycosaminoglycan, is an important constituent of the EG that regulates inflammation and repair. By providing a direct link between the endothelium and its ECM, HA contributes to maintaining glycocalyx integrity; emerging evidence indicates a close association between EG deterioration, concomitant loss of HA and the onset of endothelial dysfunction, a phenomenon that is involved in many disorders, including atherosclerosis, diabetes, hypertension and dyslipidemia. This review provides an overview of glycocalyx modification by pathological stimuli and considers the potential of the pharmacological targeting of HA synthesis and binding to limit endothelial dysfunction and to improve vasculoprotection.

Safe inhibition of thrombosis is a key therapeutic strategy in modern cardiovascular medicine, and both unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are commonly used in clinical practice. However, both have several drawbacks, such as the unpredictable pharmacokinetics of UFH and the non-reversibility of LMWH. M-118, being developed by Momenta Pharmaceuticals Inc, is a novel LMWH that has been engineered to overcome the drawbacks of UFH and currently available LMWHs, while maintaining their beneficial attributes. In preclinical studies and phase I clinical trials, M-118 demonstrated potent activity against thrombin and Factor Xa, which could be reversed with protamine; M-118 also demonstrated a high and predictable bioavailability, and a short half-life. Promising results were observed in a phase II clinical trial in patients undergoing coronary interventions, although phase III clinical trials are required to establish the role for M-118 in contemporary medicine.

Macitentan (ACT-064992), under development by Actelion Ltd in collaboration with Japanese licensee Nippon Shinyaku Co Ltd, is an orally active, non-peptide dual endothelin (ET)(A) and ET(B) receptor antagonist for the potential treatment of idiopathic pulmonary fibrosis (IPF) and pulmonary arterial hypertension (PAH). Scientific evidence suggests that the ET system may play an important role in the pathobiology of several cardiovascular diseases. A major therapeutic advance for the treatment of patients with PAH and IPF has been the pharmacological control of the activated ET system with ET receptor antagonists. Macitentan, because of its ability to target the tissues and to block both ET(A) and ET(B) receptors, is emerging as a new agent to treat cardiovascular disorders associated with chronic tissue ET system activation. The phase I and II clinical trials conducted to date have demonstrated that macitentan increases plasma levels of ET-1, displays dose-dependent pharmacokinetics, and was well tolerated in healthy volunteers and patients. At the time of publication, a phase II trial in patients with IPF and a phase III trial in patients with PAH was ongoing. It is expected that the results of these trials will validate the safety and efficacy of macitentan.

Comparative effectiveness studies of medications or, more appropriately, studies comparing the safety and efficacy of drugs have been conducted for decades, particularly for cancer chemotherapy. Research oncologists can stratify individuals participating in studies using prognostic criteria based on tissue diagnosis and disease staging. Conversely, research cardiologists, in particular those evaluating drugs for atherosclerotic vascular disease, have had to stratify individuals using criteria based on the risk of having a vascular event (ie, coronary heart disease risk). During the past 20 years, new imaging techniques, such as coronary calcium scoring, that are able to screen asymptomatic populations for atherosclerosis have been developed. In the future, studies comparing drugs for cardiovascular disease should be based on the presence of disease, such as atherosclerosis, rather than on the risk of a vascular event.

The nitric oxide (NO)/soluble guanylate cyclase (sGC)/cyclic guanosine-3',5'-monophosphate (cGMP) pathway plays an important role in cardiovascular regulation by producing vasodilation and inhibiting platelet aggregation and vascular smooth muscle proliferation. The NO/SGC/cGMP pathway is disrupted in patients with heart failure as a result of a decrease in NO bioavailability and an increase in NO-insensitive forms of sGC, resulting in insufficient vasodilation. Drugs that activate sGC in a NO-independent manner may provide considerable therapeutic advantages in treating these patients. Cinaciguat (BAY-58-2667), currently in development by Bayer AG, preferentially activates sGC in its oxidized or heme-free state, when the enzyme is insensitive to both NO and nitrovasodilators. Cinaciguat exhibits potent vasodilator and antiplatelet activity, a long-lasting antihypertensive effect and a hemodynamic profile similar to that of nitrates. In clinical trials in patients with acute decompensated heart failure, cinaciguat potently unloaded the heart, increased cardiac output and renal blood flow, and preserved renal function and sodium and water excretion without further neurohumoral activation. The pharmacokinetics of cinaciguat demonstrated dose-proportionality with low individual variability and a low incidence of adverse events. The phase I and II clinical trials performed with cinaciguat so far, however, are insufficient to provide convincing evidence on the efficacy and safety of the drug. Thus, caution should be exerted before extrapolating the present preliminary data to the clinical practice.