Bonnie Fijal

Variation in Catechol-O-Methyltransferase Is Associated with Duloxetine Response in a Clinical Trial for Major Depressive Disorder

BACKGROUND The study objective was to evaluate variations in genes implicated in antidepressant mechanism of action for association with response to duloxetine treatment in major depressive disorder (MDD). METHODS We assessed response over 6 weeks in 250 duloxetine-treated Caucasian patients in a randomized, double-blind study of patients with MDD. Single nucleotide polymorphisms (SNPs) were genotyped in 19 candidate genes selected based on evidence for involvement in antidepressant mechanism of action. Primary analysis examined baseline to end point reduction in the 17-item Hamilton Depression Rating Scale (HAMD17) total score, using a set-based test for association for each gene. Follow-up analyses examined individual SNPs within any significant gene for association with reduction in HAMD17 and 30-item Inventory of Depressive Symptomatology-Clinician Rated (IDS-C-30). RESULTS After correction for multiple comparisons, only COMT was associated with change in HAMD17 (experiment wide p = .018). Peak association was detected with rs165599 (p = .006), which accounted for approximately 3% of variance in HAMD17 change and >4% of variance in IDS-C-30 change (p = .001). The least-squared mean change (SE) in HAMD17 score by rs165599 genotype was -10.8 (1.2), -8.7 (.6), and -6.5 (.7) for patients with GG, GA, and AA genotypes, respectively. For SNPs in serotonin 2A receptor (HTR2A) previously associated with citalopram response, including rs7997012, no significant evidence of association with duloxetine response was identified. CONCLUSIONS Single nucleotide polymorphisms in COMT were associated with symptom change in duloxetine-treated patients with MDD. If replicated, the magnitude of the COMT genotype effect is of clinical relevance.

Failure to Replicate Genetic Associations with Antidepressant Treatment Response in Duloxetine-Treated Patients

BACKGROUND Recent studies have identified associations of polymorphisms in several target genes with antidepressant treatment response of serotonin reuptake inhibitors and a tricyclic antidepressant. We sought to replicate these associations in a study of a serotonin-norepinephrine reuptake inhibitor. METHODS In 250 outpatients with nonpsychotic major depressive disorder, response to treatment with once-daily duloxetine (60 mg/day) over 6 weeks was examined for associations with polymorphisms in eight candidate genes previously associated with antidepressant response using mixed-effect model repeated-measures analysis. Treatment response was quantified on the basis of changes from baseline using 17-item Hamilton Depression Rating Scale total scores. RESULTS Polymorphisms in PDE1A, PDE1C, PDE6A, PDE11A, ABCB1, GRIK4, SLC6A4, and OPRM1 genes showed no statistically significant associations (uncorrected, two-tailed p > .05) with duloxetine treatment response. CONCLUSIONS Previously, described associations between polymorphisms in candidate genes and antidepressant treatment response were not replicated in this study. This result may suggest that previous associations are specific to serotonin reuptake inhibitors.

Candidate-gene association analysis of response to risperidone in African-American and white patients with schizophrenia

Clinical trial data were evaluated for the association between 22 single-nucleotide polymorphisms (SNPs) and response in acutely ill patients diagnosed with schizophrenia, schizoaffective disorder or schizophreniform disorder, who were treated with oral risperidone. All patients in the exploratory (78 African Americans) and validation (65 whites) data sets received risperidone 2–6 mg per day over 2–12 weeks. Two SNPs were found to have significant associations with response to risperidone over 2–12 weeks in both African-American and white patients and had a consistent direction of effect in both cohorts. Metabotropic glutamate receptor (GRM3) SNP, rs724226, was associated with a change in the positive and negative syndrome scale (PANSS) total response. Catechol-O-methyltransferase (COMT) SNP, rs165599, was moderately associated with a change in the PANSS Negative score. The greater prevalence of poor-responder GRM3 and COMT alleles in white versus African-American patients might have a clinical significance in evaluating the ethnic-specific response to risperidone.

Genetic association study of treatment response with olanzapine/fluoxetine combination or lamotrigine in bipolar I depression

OBJECTIVE To evaluate common genetic variations for association with symptomatic improvement in bipolar I depression following treatment with olanzapine/fluoxetine combination (OFC) or lamotrigine. METHOD Symptom improvement was assessed in 88 OFC-treated and 85 lamotrigine-treated white patients with bipolar I depression in the 7-week acute period of a randomized, double-blind study comparing OFC (6/25, 6/50, 12/25, or 12/50 mg/d [olanzapine/fluoxetine]) with lamotrigine (titrated to 200 mg/d). The original study was conducted from November 2003 to August 2004. Single nucleotide polymorphisms (SNPs) were genotyped in a set of 19 candidate genes corresponding to known sites of activity for olanzapine and fluoxetine or previously associated with antidepressant or antipsychotic response. Primary outcome was the reduction in Montgomery-Asberg Depression Rating Scale (MADRS) total score as assessed by the difference by genotype from baseline to week 7 from a mixed-effects repeated measures analysis with terms for visit, genotype, genotype-by-visit interaction, and baseline MADRS score as a covariate. RESULTS SNPs within the dopamine D(3) receptor and histamine H(1) receptor (HRH1) genes were significantly associated with response to OFC. SNPs within the dopamine D(2) receptor, HRH1, dopamine beta-hydroxylase, glucocorticoid receptor, and melanocortin 2 receptor genes were significantly associated with response to lamotrigine. CONCLUSIONS SNPs in specific candidate genes were associated with symptomatic improvement in a treatment-specific fashion. These results suggest the importance of dopaminergic effects in the treatment of patients with bipolar I depression and the potential utility of genotyping in selection of pharmacologic treatments for bipolar depression.

Gain and loss of function of P2X7 receptors: mechanisms, pharmacology and relevance to diabetic neuropathic pain

BackgroundGenetic causes of exaggerated or reduced pain sensitivity in humans are well known. Recently, single nucleotide polymorphisms (SNPs) in the gene P2RX7, coding for the ATP-gated ion channel P2X7, have been described that cause gain-of-function (GOF) and loss-of-function (LOF), respectively of this channel. Importantly, P2RX7 SNPs have been associated with more or less severe pain scores in patient suffering of post-mastectomy pain and osteoarthritis.ResultsThe functional consequences of some P2RX7 SNPs (rs208294 (His155Tyr), rs1718119 (Ala348Thr) and rs3751143 (Glu496Ala)) were studied in recombinant cells in vitro. Our findings suggest a correlation between GOF and LOF of P2X7 and actual channel protein expression. Both channel and pore function for these mutant P2X7 receptors changed in parallel to protein levels. On the other hand, the mutant receptors did not differ in their sensitivity to known P2X7 agonists and antagonists. We further demonstrated that in patients with diabetic peripheral neuropathic pain (DPNP), the presence of the GOF SNPs rs208294 (His155Tyr) and rs1718119 (Ala348Thr) is associated, in females, with higher pain intensity scores.ConclusionsOur present results confirm the physiological relevance of some of the SNPs in the P2RX7 gene and show that the presence of these genetic variants correlates with pain sensitivity also in a diabetic neuropathic pain patient population.

Analysis of gene variants previously associated with iloperidone response in patients with schizophrenia who are treated with risperidone.

OBJECTIVE We examined 6 single nucleotide polymorphisms (SNPs) previously reported to be associated with response to iloperidone therapy for association with response to risperidone therapy. METHOD Patients with schizophrenia (DSM-IV) were assessed during 2006 and 2007 for response/nonresponse (defined as ≥ 20%/<20% improvement in Positive and Negative Syndrome Scale [PANSS] total score) after 2 weeks of risperidone treatment (2 to 6 mg/d). Responders continued risperidone treatment; nonresponders were randomly assigned to either risperidone or olanzapine treatment (10 to 20 mg/d) for an additional 10 weeks. Associations between change in PANSS total (primary outcome measure), positive, and negative scores and the 6 SNPs were examined in risperidone-treated patients (N = 145). Genotype frequencies and improvement in PANSS total scores were analyzed for those SNPs significantly associated with change in PANSS total score. RESULTS The SNPs XKR4 rs9643483 and GRIA4 rs2513265 were significantly associated with change in PANSS total response (adjusted P < .05 for both), with the same direction of effect as reported for iloperidone. For patients with nonresponsive genotypes for these SNPs, mean improvement in PANSS total score for African Americans was two-thirds that seen for whites (XKR4: -13.9 versus -21.4; GRIA4: -12.5 versus -20.9). CONCLUSIONS In this retrospective pharmacogenomic analysis, we found that 2 SNPs previously linked to iloperidone response were also associated with response to risperidone. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00337662.

Pharmacogenomic associations with weight gain in olanzapine treatment of patients without schizophrenia.

OBJECTIVE Pharmacogenomic analyses of weight gain during treatment with second-generation antipsychotics have resulted in a number of associations with variants in ankyrin repeat and kinase domain containing 1 (ANKK1)/dopamine D2 receptor (DRD2) and serotonin 2C receptor (HTR2C) genes. These studies primarily assessed subjects with schizophrenia who had prior antipsychotic exposure that may have influenced the amount of weight gained from subsequent therapies. We assessed the relationships between single-nucleotide polymorphisms (SNPs) in these genes with weight gain during treatment with olanzapine in a predominantly antipsychotic-naive population. METHOD The association between 5 ANKK1, 54 DRD2, and 11 HTR2C SNPs and weight change during 8 weeks of olanzapine treatment was assessed in 4 pooled studies of 205 white patients with diagnoses other than schizophrenia who were generally likely to have had limited previous antipsychotic exposure. RESULTS The A allele of DRD2 rs2440390(A/G) was associated with greater weight gain in the entire study sample (P = .0473). Three HTR2C SNPs in strong linkage disequilibrium, rs6318, rs2497538, and rs1414334, were associated with greater weight gain in women but not in men (P = .0032, .0012, and .0031, respectively). A significant association with weight gain for 2 HTR2C SNPs previously reported associated with weight gain, -759C/T (rs3813929) and -697G/C (rs518147), was not found. CONCLUSIONS Associations between weight gain and HTR2C and DRD2 variants in whites newly exposed to olanzapine may present opportunities for the individualization of medication selection and development based on differences in adverse events observed across genotype groups.

Pharmacogenetic investigation of response to duloxetine treatment in generalized anxiety disorder

We examined genetic associations with duloxetine response in generalized anxiety disorder (GAD). Three pooled studies in patients with GAD receiving duloxetine 60–120 mg per day (N=164) or placebo (N=95) were used. Associations between 825 single-nucleotide polymorphisms (SNPs) in 61 candidate genes with change in Hamilton Anxiety Scale scores were examined with set-based testing (adjusted for the number of SNPs within each gene); sets with two-sided adjusted P⩽0.05 were examined using repeated measure analysis. Follow-up analysis explored associations of these SNPs with change in Hamilton Rating Scale for Depression-Anxiety Subscale in a 6-week study in duloxetine-treated patients with major depressive disorder (MDD) (N=241). Variants in corticotropin-releasing hormone receptor 1 (CRHR1), dopamine receptor D3 (DRD3), nuclear receptor subfamily group C, member 1 (NR3C1) and phosphodiesterase 1A (PDE1A) were associated with duloxetine response in GAD. Only rs4792888 in CRHR1 showed modest evidence of association with duloxetine response in MDD (P=0.029 in GAD, P=0.054 in MDD). In conclusion, CRHR1 variation merits investigation in pathophysiology of anxiety and its treatment response.

Genetic associations of prolactin increase in olanzapine/fluoxetine combination-treated patients.

In patients from two clinical trials, we investigated the associations of single nucleotide polymorphisms (SNPs) in candidate genes with prolactin level changes during treatment with olanzapine/fluoxetine combination. In both cohorts, three dopamine receptor D2 (DRD2) SNPs were associated with prolactin changes. DRD2 may influence susceptibility to hyperprolactinemia associated with antipsychotic treatment.

CYP2D6 predicted metabolizer status and safety in adult patients with attention-deficit hyperactivity disorder participating in a large placebo-controlled atomoxetine maintenance of response clinical trial.

Atomoxetine, which is indicated for treatment of attention‐deficit hyperactivity disorder (ADHD), is predominantly metabolized by genetically polymorphic cytochrome P450 2D6 (CYP2D6). Based on identified CYP2D6 genotypes, individuals can be categorized into 4 phenotypic metabolizer groups as ultrarapid, extensive, intermediate, and poor. Previous studies have focused on observed differences between poor and extensive metabolizers, but it is not well understood whether the safety profile of intermediate metabolizers differs from that of ultrarapid and extensive metabolizers. This study compared safety and tolerability among the different CYP2D6 metabolizer groups in the 12‐week open‐label phase of an atomoxetine study in adult patients with ADHD. Genotyping identified 1039 patients as extensive/ultrarapid metabolizers, 780 patients as intermediate metabolizers, and 117 patients as poor metabolizers. Common (≥5% frequency) treatment‐emergent adverse events did not significantly differ between extensive/ultrarapid and intermediate metabolizers (odds ratios were <2.0 or >0.5). Poor metabolizers had higher frequencies of dry mouth, erectile dysfunction, hyperhidrosis, insomnia, and urinary retention compared with the other metabolizer groups. There were no significant differences between extensive/ultrarapid and intermediate metabolizers in changes from baseline in vital signs. These results suggest that data from CYP2D6 intermediate and extensive/ultrarapid metabolizers can be combined when considering safety analyses related to atomoxetine.