Maria Athanasiou

Candidate Gene Analysis Identifies a Polymorphism in HLA-DQB1 Associated With Clozapine-Induced Agranulocytosis

OBJECTIVE Clozapine is considered to be the most efficacious drug to treat schizophrenia, although it is underutilized, partially due to a side effect of agranulocytosis. This analysis of 74 candidate genes was designed to identify an association between sequence variants and clozapine-induced agranulocytosis (CIA). METHOD Blood and medical history were collected for 33 CIA cases and 54 clozapine-treated controls enrolled between April 2002 and December 2003. Significant markers from 4 genes were then assessed in an independently collected case-control cohort (49 CIA cases, 78 controls). RESULTS Sequence variants in 5 genes were found to be associated with CIA in the first cohort: HLA-DQB1, HLA-C, DRD1, NTSR1, and CSF2RB. Sequence variants in HLA-DQB1 were also found to be associated with CIA in the second cohort. After refinement analyses of sequence variants in HLA-DQB1, a single SNP (single nucleotide polymorphism), 6672G>C, was found to be associated with risk for CIA; the odds of CIA are 16.9 times greater in patients who carry this marker compared to those who do not. CONCLUSIONS A sequence variant (6672G>C) in HLA-DQB1 is associated with increased risk for CIA. This marker identifies a subset of patients with an exceptionally high risk of CIA, 1,175% higher than the overall clozapine-treated population under the current blood-monitoring system. Assessing risk for CIA by testing for this and other genetic variants yet to be determined may be clinically useful when deciding whether to begin or continue treatment with clozapine.

A Randomized, Double-Blind, Placebo-Controlled, 8-Week Study of Vilazodone, a Serotonergic Agent for the Treatment of Major Depressive Disorder

OBJECTIVE To evaluate the efficacy, and further establish the safety profile, of oral once-daily vilazodone, a potent and selective serotonin 1A receptor partial agonist and reuptake inhibitor, in the treatment of major depressive disorder (MDD). METHOD This phase 3, randomized, double-blind, placebo-controlled, 8-week study (conducted March 2008-February 2009) enrolled 481 adults with DSM-IV-TR-defined MDD. Patients received vilazodone (titrated to 40 mg/d) or placebo. The primary efficacy endpoint was change in Montgomery-Asberg Depression Rating Scale (MADRS) total score from baseline to end of treatment. Secondary efficacy measures included MADRS and 17-item Hamilton Depression Rating Scale (HDRS-17) response and change in HDRS-17, HDRS-21, Hamilton Anxiety Rating Scale (HARS), Clinical Global Impressions-Severity of Illness (CGI-S), and Clinical Global Impressions-Improvement (CGI-I) scores. The Changes in Sexual Functioning Questionnaire (CSFQ) was administered at baseline and week 8. RESULTS Vilazodone-treated patients had significantly greater improvement (P = .009) according to the MADRS than placebo patients (intent-to-treat; least-squares mean changes: -13.3, -10.8). MADRS response rates were significantly higher with vilazodone than placebo (44% vs 30%, P = .002). Remission rates for vilazodone were not significantly different based on the MADRS (vilazodone, 27.3% vs placebo, 20.3%; P = .066) or HDRS-17 (vilazodone, 24.2% vs placebo, 17.7%; P = .088). Vilazodone-treated patients had significantly greater improvements from baseline in HDRS-17 (P = .026), HDRS-21 (P = .029), HARS (P = .037), CGI-S (P = .004), and CGI-I (P = .004) scores than placebo patients. Rates of discontinuation due to adverse events were 5.1% (vilazodone) and 1.7% (placebo). The most common adverse events (vilazodone vs placebo) were diarrhea (31% vs 11%), nausea (26% vs 6%), and headache (13% vs 10%). Treatment-related effects on sexual function as measured by the CSFQ were small and similar to placebo. Effects on weight were no different from placebo. CONCLUSIONS Vilazodone 40 mg/d was well tolerated and effective in adult patients with MDD. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00683592.

The efficacy profile of vilazodone, a novel antidepressant for the treatment of major depressive disorder.

Abstract Objective: Vilazodone is a novel serotonin reuptake inhibitor and serotonin 1A receptor partial agonist approved for the treatment of major depressive disorder (MDD). This evaluation presents side-by-side efficacy data from two randomized, double-blind, placebo-controlled, short-term 8-week trials (referred to as randomized controlled trial [RCT]-1 [N = 410] and RCT-2 [N = 481]); efficacy data for demographic and clinical subgroups (derived from pooled RCT data); and effectiveness data from a 52-week, open-label, long-term study (N = 616). The objective is to summarize the efficacy profile of vilazodone at its approved dose of 40 mg/day. Methods: The main assessment in individual pivotal trials and pooled subgroup analyses was the change from baseline to end of treatment (EOT, 8 weeks) in the Montgomery–Åsberg Depression Rating Scale (MADRS) total score. Mixed-effects repeated-measures analyses were conducted in the placebo-controlled trials. Effectiveness analyses in the long-term study included mean MADRS score change over time. Results: Vilazodone-treated patients in both short-term studies showed greater improvement from baseline to EOT in mean MADRS scores than placebo-treated patients (least-squares mean [LSM] treatment difference: −3.2 [p = 0.001], RCT-1; −2.5 [p = 0.009], RCT-2). Clinical Global Impressions–Improvement mean scores at EOT reflected greater improvement with vilazodone compared with placebo in both studies (LSM treatment difference: −0.4 [p = 0.001], RCT-1; −0.3 [p = 0.004], RCT-2). MADRS response rates were significantly greater among patients receiving vilazodone versus those receiving placebo (RCT-1: 40.4% versus 28.1%, respectively [p = 0.007]; RCT-2: 43.7% versus 30.3%, respectively [p = 0.002]). The greater efficacy of vilazodone versus placebo was consistent for the majority of demographic and MDD characteristic subgroups. In the long-term study, the mean MADRS score improved from 29.9 (baseline) to 11.4 (week 8), 8.2 (week 24), and 7.1 (week 52). Conclusion: Vilazodone 40 mg/day resulted in clinically meaningful, statistically significant improvement in MDD symptoms in two placebo-controlled, 8-week studies. Findings are supported by subgroup analysis and open-label, long-term effectiveness data. Trial registration: Trial registration: ClinicalTrials.gov identifier: NCT00285376. Trial registration: ClinicalTrials.gov identifier: NCT00683592. Trial registration: ClinicalTrials.gov identifier: NCT00644358.

Electrophysiological evidence for rapid 5-HT1A autoreceptor inhibition by vilazodone, a 5-HT1A receptor partial agonist and 5-HT reuptake inhibitor

This study examined the effect of vilazodone, a combined serotonin (5-HT) reuptake inhibitor and 5-HT(1A) receptor partial agonist, paroxetine and fluoxetine on the sensitivity of 5-HT(1A) autoreceptors of serotonergic dorsal raphe nucleus neurons in rats. These effects were assessed by determining the intravenous dose of (±)-8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) required to suppress the basal firing rate of these neurons by 50% (ID₅₀) in anesthetized rats using in vivo electrophysiology. 5-HT uptake inhibition was determined by the ability of the compounds to reverse (±)-p-chloroamphetamine (PCA)-induced rat hypothalamic 5-HT depletion ex vivo. Acute vilazodone administration (0.63 and 2.1 µmol/kg, s.c.), compared with vehicle, significantly increased (2-3-fold) the ID₅₀ of 8-OH-DPAT at 4 h, but not 24h after administration. Subchronic administration (3 days) significantly increased the ID₅₀ value at 4 h (3-4-fold) and at 24 h (~2-fold). In contrast, paroxetine and fluoxetine at doses that were supramaximal for 5-HT uptake inhibition did not significantly alter the ID₅₀ value of 8-OH-DPAT after acute or subchronic administration. Vilazodone antagonized the action of PCA 3.5 h and 5 h after a single dose (ID₅₀ 1.49 and 0.46 µmol/kg, s.c., respectively), but was inactive 18 h post-administration, corroborating the electrophysiological results at 24 h following acute administration. The results are consistent with the concept of rapid and, following repeated treatment, prolonged inhibition of 5-HT(1A) autoreceptors by vilazodone. This effect could occur by either direct interaction with, or desensitization of, these receptors, an effect which cannot be ascribed to vilazodones 5-HT reuptake inhibiting properties.

Vilazodone, a novel, dual-acting antidepressant: current status, future promise and potential for individualized treatment of depression

Vilazodone is a novel antidepressant with a dual mechanism of action that combines selective serotonin reuptake inhibition and partial 5-hydroxytryptamine1A receptor agonism. Vilazodone is undergoing clinical development for the treatment of major depressive disorder and has demonstrated antidepressant efficacy. In addition, in a placebo-controlled, randomized study, vilazodone has been shown to be well tolerated with a low discontinuation rate due to adverse events. Importantly, in this study, the incidence of sexual dysfunction with vilazodone was similar to that of the placebo. A key feature of the vilazodone clinical development program is the identification and development of biomarkers that predict response to therapy. This article will review the pharmacology, efficacy and tolerability, and pharmacogenetic data of vilazodone for the treatment of major depressive disorder. Vilazodone may be the first antidepressant to provide targeted therapy to patients most likely to achieve a response, and to offer an individualized approach to therapy.

The Role of Pharmacogenetics in Treating Central Nervous System Disorders

Symptoms of central nervous system (CNS) disorders include abnormalities in both physical and psychological domains. Many drugs indicated for the treatment of CNS disorders are fraught with side effects and/or poor efficacy which impact patients’ quality of life and drives non-compliance. Moreover, for many CNS drugs such as antidepressants and antipsychotics, it takes time to determine whether a particular drug is efficacious in an individual patient. To optimize drug treatment for each patient, prescribing physicians often need to raise or lower doses, switch drug classes, or prescribe additional drugs to mitigate side effects, often in a “trial and error” fashion. Pharmacogenetic (PGx) testing, particularly in the realm of CNS therapy, can reduce the unpredictability of this process. By determining a patient’s genetic profile, individual therapy parameters may be predicted pre-treatment for drug efficacy, optimal drug dose, and the risk of adverse drug reactions (ADRs). The intent of this review is to highlight the power of PGx testing to predict the likelihood of ADRs and efficacy during the treatment of the following CNS disorders: epilepsy, bipolar disorder, schizophrenia and depression.

Restoring value to stalled Phase II compounds: the case for developing a novel compound for depression using pharmacogenetics

While the best examples of personalized, or pharmacogenetically guided, therapeutics are those developed in the field of oncology, key attributes of these successful examples can be used as a basis for the selection of other candidates for development using pharmacogenetics. With the field of depression as an example, we highlight the technological, medical and commercial attributes that will lead to the successful implementation of pharmacogenetics into a drug development plan. Vilazodone, a novel dual-mechanism serotonergic antidepressant, is used as a specific example of how pharmacogenetics can be applied to ‘rescue’ compounds believed to be effective but stalled due to insufficient overall efficacy.