Carol R. Reed

The SLCO1B1*5 Genetic Variant Is Associated With Statin-Induced Side Effects

OBJECTIVES We sought to identify single nucleotide polymorphisms associated with mild statin-induced side effects. BACKGROUND Statin-induced side effects can interfere with therapy. Single nucleotide polymorphisms in cytochrome P450 enzymes impair statin metabolism; the reduced function SLCO1B1*5 allele impairs statin clearance and is associated with simvastatin-induced myopathy with creatine kinase (CK) elevation. METHODS The STRENGTH (Statin Response Examined by Genetic Haplotype Markers) study was a pharmacogenetics study of statin efficacy and safety. Subjects (n = 509) were randomized to atorvastatin 10 mg, simvastatin 20 mg, or pravastatin 10 mg followed by 80 mg, 80 mg, and 40 mg, respectively. We defined a composite adverse event (CAE) as discontinuation for any side effect, myalgia, or CK >3x upper limit of normal during follow-up. We sequenced CYP2D6, CYP2C8, CYP2C9, CYP3A4, and SLCO1B1 and tested 7 reduced function alleles for association with the CAE. RESULTS The CAE occurred in 99 subjects (54 discontinuations, 49 myalgias, and 9 CK elevations). Sex was associated with CAE (percent female in CAE vs. no CAE groups, 66% vs. 50%, p < 0.01). SLCO1B1*5 was associated with CAE (percent with > or = 1 allele in CAE vs. no CAE groups, 37% vs. 25%, p = 0.03) and those with CAE with no significant CK elevation (p < or = 0.03). Furthermore, there was evidence for a gene-dose effect (percent with CAE in those with 0, 1, or 2 alleles: 19%, 27%, and 50%, trend p = 0.01). Finally, the CAE risk appeared to be greatest in those carriers assigned to simvastatin. CONCLUSIONS SLCO1B1*5 genotype and female sex were associated mild statin-induced side effects. These findings expand the results of a recent genome-wide association study of statin myopathy with CK >3x normal to milder, statin-induced, muscle side effects.

Prevalence of early-onset atrial fibrillation in congenital long QT syndrome

BACKGROUND The prevalence of atrial fibrillation (AF) in the young (age <50 years) is 0.1%, or 1:1,000 persons. Mutations in KCNQ1-, KCNH2-, and KCNA5-encoded potassium channels and SCN5A-encoded sodium channels have been reported in familial AF. A mechanism of atrial torsade has been suggested to occur in patients with congenital long QT syndrome (LQTS). OBJECTIVE The purpose of this study was to determine the prevalence of AF in patients with congenital LQTS. METHODS History of documented AF was sought from two independent cohorts. One cohort consisted of 252 consecutive patients (146 females and 106 males, average age at diagnosis 23 +/- 16 years, QTc 465 +/- 51 ms) with genetically proven LQTS seen at Mayos LQTS Clinic. The second cohort consisted of 205 consecutive patients (133 females and 72 males, average age at testing 23 +/- 16 years, QTc 479 +/- 51 ms) with a positive FAMILION genetic test (PGxHealth) for LQTS. RESULTS Early-onset AF was documented in 8 (1.7%) of 457 patients, including 6 (2.4%) of 252 patients seen at Mayo and 2 (1%) of 205 patients with a positive FAMILION test. Five (2.4%) of 211 patients with LQT1-susceptibility mutations had documented AF, compared to 0 of 174 patients with LQT2, 1 of 59 patients with LQT3, 1 of 1 patient with Andersen-Tawil syndrome, and 1 of 34 patients with multiple mutations. The average age at diagnosis of AF of the six patients evaluated at Mayo was 24.3 years (range 4-46 years). Early-onset AF (age <50 years) was significantly more common in patients with LQTS compared to population-based prevalence statistics (P <.001, relative risk 17.5). CONCLUSION Compared to the background prevalence of 0.1%, early-onset AF was observed in almost 2% of patients with genetically proven LQTS and should be viewed as an uncommon but possible LQT-related dysrhythmia. Clinical complaints of palpitations warrant thorough assessment in patients with LQTS.

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.

Pharmacogenetic Predictors of Statin-Mediated Low-Density Lipoprotein Cholesterol Reduction and Dose Response

Background—There is interindividual variation in low-density lipoprotein cholesterol (LDLc) lowering by statins and limited study into the genetic associations of the dose dependant LDLc lowering by statins. Methods and Results—Five hundred nine patients with hyperlipidemia were randomly assigned atorvastatin 10 mg, simvastatin 20 mg, or pravastatin 10 mg (low-dose phase) followed by 80 mg, 80 mg, and 40 mg (high-dose phase), respectively. Thirty-one genes in statin, cholesterol, and lipoprotein metabolism were sequenced and 489 single nucleotide polymorphisms with minor allele frequencies >2% were tested for associations with percentage LDLc lowering at low doses using multivariable adjusted general linear regression. Significant associations from the analysis at low dose were then repeated at high-dose statins. At low doses, only 1 single nucleotide polymorphism met our experiment-wide significance level, ABCA1 rs12003906. Twenty-six subjects carried the minor allele of rs12003906, which was associated with an attenuated LDLc reduction (LDLc reduction in carriers versus noncarriers −24.1±2.6% versus −32.2±1.5%; P=0.0001). In addition, we replicated the association with the APOE ϵ3 allele and a reduced LDLc reduction. At high doses, carriers of the minor allele of ABCA1 rs12003906 and the APOE ϵ3 allele improved their LDLc reduction but continued to have a diminished LDLc reduction compared with noncarriers (−30.5±4.0% versus −42.0±2.4%; P=0.005) and (−38.5±1.9% versus −45.3±2.8%; P=0.009), respectively. Conclusions—An intronic single nucleotide polymorphism in ABCA1 and the APOE ϵ3 allele are associated with reduced LDLc lowering by statins and identify individuals who may be resistant to maximal LDLc lowering by statins.

Pharmacogenetic predictors of statin mediated LDLc reduction and dose response

Background—There is interindividual variation in low-density lipoprotein cholesterol (LDLc) lowering by statins and limited study into the genetic associations of the dose dependant LDLc lowering by statins. Methods and Results—Five hundred nine patients with hyperlipidemia were randomly assigned atorvastatin 10 mg, simvastatin 20 mg, or pravastatin 10 mg (low-dose phase) followed by 80 mg, 80 mg, and 40 mg (high-dose phase), respectively. Thirty-one genes in statin, cholesterol, and lipoprotein metabolism were sequenced and 489 single nucleotide polymorphisms with minor allele frequencies >2% were tested for associations with percentage LDLc lowering at low doses using multivariable adjusted general linear regression. Significant associations from the analysis at low dose were then repeated at high-dose statins. At low doses, only 1 single nucleotide polymorphism met our experiment-wide significance level, ABCA1 rs12003906. Twenty-six subjects carried the minor allele of rs12003906, which was associated with an attenuated LDLc reduction (LDLc reduction in carriers versus noncarriers −24.1±2.6% versus −32.2±1.5%; P=0.0001). In addition, we replicated the association with the APOE ϵ3 allele and a reduced LDLc reduction. At high doses, carriers of the minor allele of ABCA1 rs12003906 and the APOE ϵ3 allele improved their LDLc reduction but continued to have a diminished LDLc reduction compared with noncarriers (−30.5±4.0% versus −42.0±2.4%; P=0.005) and (−38.5±1.9% versus −45.3±2.8%; P=0.009), respectively. Conclusions—An intronic single nucleotide polymorphism in ABCA1 and the APOE ϵ3 allele are associated with reduced LDLc lowering by statins and identify individuals who may be resistant to maximal LDLc lowering by statins.

A 1-year, open-label study assessing the safety and tolerability of vilazodone in patients with major depressive disorder.

Vilazodone, a selective serotonin (5-HT) reuptake inhibitor and 5-HT1A receptor partial agonist, was efficacious in two 8-week placebo-controlled studies in adults with major depressive disorder. This open-label, multicenter study assessed the long-term safety of vilazodone. Adult patients with a 17-item Hamilton Rating Scale for Depression score of 18 or greater received vilazodone according to a fixed-titration schedule to reach a dose of 40 mg/d continued up to 1 year. Safety assessments included adverse events (AEs), physical examinations, clinical chemistry, electrocardiograms, and the Changes in Sexual Functioning Questionnaire. Effectiveness was assessed with the Montgomery-Åsberg Depression Rating Scale and Clinical Global Impressions scales. The safety population comprised 599 patients; 254 patients completed 1 year of treatment. The most frequent AEs were diarrhea (35.7%), nausea (31.6%), and headache (20.0%); greater than 90% of these AEs were mild or moderate. Adverse events resulting in discontinuation in more than 1% of patients were nausea (1.3%) and diarrhea (1.2%). There were no clinically important changes in physical examinations, electrocardiograms, or clinical chemistries. Mean weight increased by 1.7 kg (observed cases). Changes in Sexual Functioning Questionnaire mean scores (observed cases) improved throughout treatment for both males and females. Montgomery-Åsberg Depression Rating Scale mean scores were 29.9 at baseline, 11.4 at week 8, and 7.1 at week 52 (observed cases). Vilazodone 40 mg/d for 1 year was safe and well tolerated by adults with major depressive disorder.

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.

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.