Current opinion in investigational drugs最新文献

The scarcity of new innovative drugs in the development pipeline for combating HIV replication may signal a change in direction for HIV researchers and drug developers. The model of introducing drugs with incremental improvements within existing drug classes is no longer commercially viable. While an argument can be made that drugs aimed at novel targets may have a greater impact, the list of such targets is limited and the scientific challenge of intervening at another stage in the HIV replication cycle is high. It is difficult to envision a realistic risk/reward scenario that will ensure continued investment in the discovery of novel HIV drugs that simply block replication and suppress plasma viral load. Recently, it has been suggested that the scientific community should move research in a new direction, with the goal of attacking the reservoirs of latent HIV that persist despite treatment with current drugs to achieve a functional cure, if not a sterilizing cure. This process will have to be a long-term commitment, primarily funded by the NIH, with some involvement by the pharmaceutical and biotechnology industries. While most individuals infected with HIV can achieve viral suppression with the current approved therapies, treatment is lifelong, side effects are significant and resistance will eventually render more of these drugs less effective. New and innovative approaches must be developed to prevent viral infection and further improve the quality of life for those individuals who are already infected.

When circadian rhythms - the daily oscillations of various physiological and behavioral events that are controlled by a central timekeeping mechanism - become desynchronized with the prevailing light:dark cycle, a maladaptative response can result. Animal data based primarily on genetic manipulations and clinical data from biomarker and gene expression studies support the notion that circadian abnormalities underlie certain psychiatric disorders. In particular, bipolar disorder has an interesting link to rhythm-related disease biology; other mood disturbances, such as major depressive disorder, seasonal affective disorder and the agitation and aggression accompanying severe dementia (sundowning), are also linked to changes in circadian rhythm function. Possibilities for pharmacological intervention derive most readily from the molecular oscillator, the cellular machinery that drives daily rhythms.

Evaluating the efficacy of a drug therapy in the acute and prophylactic treatment of migraine requires the conduct of placebo-controlled, randomized clinical trials. In order to plan and conduct these studies in the most appropriate manner, it is desirable to know which factors influence the placebo response. This editorial overview discusses the factors that influence placebo response in trials for migraine and other headaches; such factors include expectation, blinding, route of drug administration, patient age and gender, and geographic distribution of the trials. The placebo response rates in the treatment of acute headache episodes are higher than in headache prophylaxis, and invasive procedures, such as injections, have a higher placebo response compared with orally administered drugs.

Parkinson's disease (PD) is a progressive neurodegenerative disorder, the cause of which remains elusive. Neuroinflammation appears to be a ubiquitous pathological change in both patients and experimental models of PD, both of which present with the classical features of inflammation, but with evidence that the process has become uncontrolled. Therefore, the use of anti-inflammatory drugs in the treatment of PD appears to be a logical development. Preclinical studies have largely supported the potential of anti-inflammatory compounds in PD. However, reports are conflicting, and preclinical success with these compounds is generally achieved by administration prior to or at the same time as a neurotoxic insult. This regimen, therefore, fails to account for the fact that the disease process is well developed upon diagnosis in patients. Perhaps unsurprisingly, success in the clinic with anti-inflammatory PD compounds has been modest. It has been suggested that anti-inflammatory drugs may be useful as adjuncts to other therapeutic avenues, particularly drugs that aim to restore neuronal loss. Such an approach seems logical given that the etiology of PD is unlikely to arise from a single factor and, accordingly, treatment may require intervention at different mechanistic loci. This review discusses the anti-inflammatory agents that have been suggested to have potential for the treatment of PD.

Cariprazine (RGH-188), which is being codeveloped by Gedeon Richter Ltd, Forest Laboratories Inc and Mitsubishi Tanabe Pharma Corp, is a novel putative antipsychotic drug that exerts partial agonism at dopamine D2/D3 receptors, with preferential binding to D3 receptors, and partial agonism at serotonin 5-HT1A receptors. Its activity at D2/D3 receptors may be lower than that of the prototype partial agonist aripiprazole. The antipsychotic activity of cariprazine was demonstrated in animal models, and data also suggest that the propensity for extrapyramidal side effects is low and that the drug may have procognitive properties. Cariprazine is rapidly absorbed, with high oral bioavailability and a long plasma elimination t1/2. Cariprazine is in phase III clinical trials in patients with schizophrenia and in patients with bipolar disorder. Data from phase II trials in patients with schizophrenia and bipolar mania indicate that the drug has antipsychotic and antimanic properties that are superior to placebo. With its unique receptor affinity profile, cariprazine may represent a potential enrichment of the therapeutic armamentarium for schizophrenia and affective disorders. Its activity against the cognitive deficits associated with schizophrenia has to be carefully investigated.

The use of MRI-based imaging in drug development has received increased interest recently because of the difficulties associated with the development of CNS pharmacotherapies. While not yet routine, there have been significant advances in imaging that allow this technology to be used for evaluating disease state and drug effects. For disease states, both single and longitudinal studies of non-invasive measures may be obtained to provide a read-out of disease processes and, potentially, to predict the disease state and its evolution. In addition, imaging has enabled the development of improved preclinical disease models based on changes in brain circuitry. Pharmacological MRI, the imaging-based evaluation of drug effects, includes measures of direct effects on the brain, as well as the effects of chronic dosing on brain changes and neurochemical changes associated with these brain effects using magnetic resonance spectroscopy. Thus, imaging may become an integrated process in drug development, during both the preclinical and clinical stages. However, validation, the implementation of good clinical practices and regulatory acceptance are hurdles that remain to be overcome.

Currently, there are two drugs on the market, gabapentin (Neurontin) and pregabalin (Lyrica), that are proposed to exert their therapeutic effect through binding to the alpha2-delta subunit of voltage-sensitive calcium channels. This activity was unexpected, as the alpha2-delta subunit had previously been considered not to be a pharmacological target. In this review, the role of the alpha2-delta subunits is discussed and the mechanism of action of the alpha2-delta ligands in vitro and in vivo is summarized. Finally, new insights into the mechanism of drugs that bind to this protein are discussed.

Biomarkers serve as the fundamental building blocks of modern translational research strategies, and are widely implemented in current drug development. Biomarker techniques range from simple biofluid biochemical endpoints to more complex assessments, including imaging. Although biomarker usage is common throughout drug development, applications may vary depending on whether a drug candidate is in early- or late-stage testing. In early clinical drug development, biomarkers capable of providing proof of mechanism are considered critical tools in the management of attrition during phase II clinical trials. For CNS drugs, the ability to unequivocally demonstrate pharmacologically driven biological activity in the brain, as a result of the interaction of a drug with its intended target, ensures that proof-of-concept trials are designed in a manner that adequately tests the clinical efficacy hypothesis and that patients are not being exposed to inactive drugs. This review focuses on recent advances in proof-of-pharmacology biomarkers, with an emphasis on biochemical measures and simple circuit platforms used to demonstrate target engagement in central compartments.

LY-2140023 is a methionine amide prodrug of the orthosteric metabotropic glutamate receptor (mGluR)2/3 agonist LY-404039, being developed by Eli Lilly & Co, for the potential oral treatment of schizophrenia. LY-404039 is a rigid glutamate analog that selectively binds to mGluR2/3 compared with all other glutamate receptors and transporters, and with other monoaminergic receptors that have been implicated in the therapeutic efficacy of atypical antipsychotic drugs. Activation of mGluR2 has been associated with the antipsychotic-like behavioral effects of LY-404039, as indicated by experiments using mGluR2-/- and mGluR3-/- mice. Furthermore, mGluR2 acts as a glutamatergic autoreceptor in the brain regions that are believed to be important in the pathophysiology of schizophrenia, such as the prefrontal cortex, striatum, hippocampal formation and the thalamus. The antipsychotic efficacy of LY-2140023, predicted by a common battery of preclinical behavioral screens for antipsychotic drugs, was confirmed in a randomized, placebo-controlled, phase II clinical trial in patients with schizophrenia. In addition, LY-2140023 lacked the extrapyramidal and metabolic side effects that are commonly observed with the majority of currently approved antipsychotic drugs. Thus, LY-2140023 represents a rare psychiatric medicine that demonstrates the promise of being rationally developed from bench to bedside.

Serotonin 5-HT1A receptors are attractive targets for the development of improved antipsychotics. Indeed, extensive evidence in rodent models indicates that the activation of these receptors prevents extrapyramidal symptoms (EPS) induced by dopamine D2 receptor blockade, favors dopaminergic neurotransmission in the frontal cortex, has a positive influence on mood, and opposes NMDA receptor antagonist-induced cognitive and social interaction deficits. Therefore, 'third-generation' antipsychotics that combine partial agonism at 5-HT1A receptors with antagonism (or partial agonism) at D2 receptors have been investigated, including aripiprazole, perospirone, lurasidone (Dainippon Sumitomo Pharma Co Ltd), cariprazine (Gedeon Richter Ltd/Forest Laboratories Inc/Mitsubishi Tanabe Pharma Corp), PF-217830 (Pfizer Inc), F-97013-GD, F-15063 and bifeprunox. Such compounds appear to provide therapeutic benefits against a broader range of symptoms of schizophrenia, including negative symptoms and cognitive deficits that are poorly controlled by established antipsychotics. Recently developed compounds are essentially free of EPS liability, and exhibit little or no interaction at sites that are potentially involved in causing side effects such as weight gain, metabolic disorders or autonomic disturbance. These compounds differ in their balance of 5-HT1A/D2 receptor affinity and agonist or antagonist properties; such differences are likely to translate into distinct therapeutic profiles. The balance of 5-HT1A/D2 receptor properties should therefore be considered when selecting compounds as antipsychotic development candidates.