ASIED: a Bayesian adaptive subgroup-identification enrichment design.

Developing targeted therapies based on patients' baseline characteristics and genomic profiles such as biomarkers has gained growing interests in recent years. Depending on patients' clinical characteristics, the expression of specific biomarkers or their combinations, different patient subgroups could respond differently to the same treatment. An ideal design, especially at the proof of concept stage, should search for such subgroups and make dynamic adaptation as the trial goes on. When no prior knowledge is available on whether the treatment works on the all-comer population or only works on the subgroup defined by one biomarker or several biomarkers, it is necessary to incorporate the adaptive estimation of the heterogeneous treatment effect to the decision-making at interim analyses. To address this problem, we propose an Adaptive Subgroup-Identification Enrichment Design, ASIED, to simultaneously search for predictive biomarkers, identify the subgroups with differential treatment effects, and modify study entry criteria at interim analyses when justified. More importantly, we construct robust quantitative decision-making rules for population enrichment when the interim outcomes are heterogeneous in the context of a multilevel target product profile, which defines the minimal and targeted levels of treatment effect. Through extensive simulations, the ASIED is demonstrated to achieve desirable operating characteristics and compare favorably against alternatives.

Adaptive, dose-finding phase 2 trial evaluating the safety and efficacy of ABT-089 in mild to moderate Alzheimer disease.

ABT-089, an α4ß2 neuronal nicotinic receptor partial agonist, was evaluated for efficacy and safety in mild to moderate Alzheimer disease patients receiving stable doses of acetylcholinesterase inhibitors. This phase 2 double-blind, placebo-controlled, proof-of-concept, and dose-finding study adaptively randomized patients to receive ABT-089 (5, 10, 15, 20, 30, or 35 mg once daily) or placebo for 12 weeks. The primary efficacy endpoint was the Alzheimer's Disease Assessment Scale, cognition subscale (ADAS-Cog) total score. A Bayesian response-adaptive randomization algorithm dynamically assigned allocation probabilities based on interim ADAS-Cog total scores. A normal dynamic linear model for dose-response relationships and a longitudinal model for predicting final ADAS-cog score were employed in the algorithm. Stopping criteria for futility or success were defined. The futility stopping criterion was met, terminating the study with 337 patients randomized. No dose-response relationship was observed and no dose demonstrated statistically significant improvement over placebo on ADAS-Cog or any secondary endpoint. ABT-089 was well tolerated at all dose levels. When administered as adjunctive therapy to acetylcholinesterase inhibitors, ABT-089 was not efficacious in mild to moderate Alzheimer disease. The adaptive study design enabled the examination of a broad dose range, enabled rapid determination of futility, and reduced patient exposure to nonefficacious doses of the investigational compound.

Baseline observation carry forward: reasoning, properties, and practical issues.

In some longitudinal drug studies, regulatory agencies suggest baseline observation carry forward (BOCF) as a method of handling patient dropout, despite the existence of many criticisms to BOCF. The reason for using BOCF is not clear to many users who either treat BOCF as an imputation method or consider BOCF to be "conservative" in the sense that it allows treatment effect to be evaluated with a severe penalty for dropouts. In this article we address the following questions and issues: What is the reason for using BOCF? Is BOCF a conservative approach to assessing drug efficacy? Is BOCF reasonable? If not, what are the alternatives? Our discussions are based on both theoretical and practical viewpoints.

Clinical evidence for serotonin and norepinephrine reuptake inhibition of duloxetine.

Most antidepressants in clinical use are believed to function by enhancing neurotransmission of serotonin [5-hydroxytryptamine (5-HT)] and/or norepinephrine (NE) via inhibition of neurotransmitter reuptake. Agents that affect reuptake of both 5-HT and NE (serotonin-norepinephrine reuptake inhibitors) have been postulated to offer greater efficacy for the treatment of major depressive disorder (MDD). These dual-acting agents also display a broader spectrum of action, including efficacy for MDD and associated painful physical symptoms, diabetic peripheral neuropathic pain, generalized anxiety disorder, and fibromyalgia syndrome. Substantial preclinical evidence shows that duloxetine, an approved drug for the treatment of MDD, generalized anxiety disorder, and the management of diabetic peripheral neuropathic pain, inhibits reuptake of both 5-HT and NE. This paper reviews clinical and neurochemical evidence of duloxetine's effects on 5-HT and NE reuptake inhibition. The clinical evidence supporting duloxetine's effects on NE reuptake inhibition includes indirect measures such as altered excretion of NE metabolites, cardiovascular effects, and treatment-emergent adverse event profiles similar to those for other drugs believed to act through the inhibition of NE reuptake. In summary, the data presented in this report provide clinical evidence of a mechanism for duloxetine involving both 5-HT and NE reuptake inhibition in humans and are consistent with preclinical evidence for 5-HT/NE reuptake inhibition.

Use of effect size to determine optimal dose of duloxetine in major depressive disorder.

OBJECTIVE: At effective doses, patients with major depressive disorder (MDD) treated with duloxetine have been found to experience significant symptom improvement as measured by HAMD(17) total score. In addition, duloxetine-treated patients have significantly higher remission and response rates compared with placebo. The objective of this analysis is to determine the optimal dose of duloxetine in MDD. MATERIALS AND METHODS: Effect size for duloxetine 40mg, 60mg, 80mg, and 120mg per day were estimated using all 6 acute phase III clinical trials in patients with MDD. The tolerability of duloxetine 40mg, 60mg, 80mg, and 120mg were evaluated using pooled data from the 6 studies. The primary efficacy measure in all trials was the HAMD(17) total score, from which were determined the effect size for HAMD(17) change scores, response rates (50% reduction from baseline to endpoint), and remission rates (HAMD(17) total score < or =7). RESULTS: A total of 1619 randomized patients were included in these studies, of which 632 were treated with placebo; 177 with duloxetine 40mg/day; 251 with 60mg/day; 363 with 80mg/day; and 196 with 120mg/day. An evaluation of increments in effect size between doses consistently showed that the most notable gain in effect size for efficacy was the 40-60mg/day dosage range. All dosages from 60 to 120mg were effective. The tolerability assessment indicated duloxetine at 40-120mg/day is well tolerated. Furthermore, the initial doses of 40-80mg/day were found to have comparable tolerability. CONCLUSIONS: The effect size analyses demonstrate that duloxetine 40mg has minimum efficacy, and that duloxetine 60-120mg/day is effective in the treatment of patients with MDD. An initial dose less than 60mg/day might provide better tolerability for some patients diagnosed with MDD.

Efficacy of duloxetine in painful symptoms: an analgesic or antidepressant effect?

The evidence that the effects of the antidepressant duloxetine on painful physical symptoms in depression and chronic pain disorders are a direct analgesic effect rather than an indirect antidepressant effect is reviewed. Data from placebo-controlled acute studies of duloxetine in major depressive disorder, diabetic peripheral neuropathic pain and fibromyalgia syndrome are included in this review. In placebo-controlled studies of duloxetine in patients with major depressive disorder, non-depressed diabetic peripheral neuropathic pain, and fibromyalgia syndrome, duloxetine has a statistically significantly greater effect on pain than placebo. Path analysis suggests that in these patient populations, approximately 50, 90, and 80%, respectively, of the observed effect on pain is a direct analgesic effect rather than an indirect antidepressant effect. In fibromyalgia syndrome studies, duloxetine had similar and substantial effects on pain regardless of whether patients had comorbid major depressive disorder. Pain is a complex experience, involving both the physiological responses of the nociceptive system and the processing of that information in brain regions associated with emotion. While some effects of duloxetine on painful symptoms can be accounted for by its antidepressant action, the data strongly suggest that duloxetine also exerts a substantial direct analgesic effect over and above its antidepressant effects, in patients with major depressive disorder, diabetic peripheral neuropathic pain, and fibromyalgia syndrome.

Duloxetine in the long-term management of diabetic peripheral neuropathic pain: An open-label, 52-week extension of a randomized controlled clinical trial.

BACKGROUND: Duloxetine hydrochloride, a selective serotonin (5-HT) and norepinephrine (NE) reuptake inhibitor, is relatively balanced in its affinity for both 5-HT and NE reuptake inhibition and is the first US Food and Drug Administration-approved prescription drug for the management of diabetic peripheral neuropathic pain (DPNP). OBJECTIVES: The aim of this study was to determine whether management of DPNP with duloxetine interferes with the treatment of diabetes. It also examined the tolerability of long-term exposure to duloxetine with regard to the progression of diabetic complications, and assessed the impact of DPNP management with duloxetine versus routine care. METHODS: This was a 52-week, multicenter, re-randomized, open-label extension of a parallel, double-blind, randomized, placebo-controlled, acute (12-week) study. Patients who completed the duloxetine or placebo acute treatment period were randomly reassigned in a 2:1 ratio to treatment with duloxetine 60 mg BID or routine care for an additional 52 weeks. The study included male and female outpatients aged ≥18 years with a diagnosis of DPNP caused by type 1 or type 2 diabetes. Over the course of the 52-week study, visits were scheduled on the following weeks (of the extension phase of the study): 1 (via phone only), 2, 4, 8, 12, 20, 28, 40, and 52. Tolerability was assessed by review and analyses of discontinuation rates, adverse events (AEs), laboratory data, vital signs, electrocardiographic results, concomitant medications, and diabetic complications. Treatment-emergent AEs (TEAEs) were defined as AEs that appeared during therapy (were not present at baseline) or were exacerbated during treatment. Data on AEs and concomitant medications were collected at every visit. Data on blood pressure, heart rate, and significant hypoglycemic events were collected at every visit starting from week 2. Fasting clinical chemistry and electrolyte group laboratory assessments were done at every visit, starting from week 4. Electrocardiographic data was collected at weeks 4 and 52, and glycosylated hemoglobin and lipid profile data were collected at weeks 20 and 52. Hematology and urinalysis laboratory assessments and diabetic complication assessments were done at week 52. All safety data was assessed in cases of early discontinuation. Treatment differences on quality of life (QOL) were compared using the Short Form-36 Health Status Survey (SF-36) and the EQ-5D instrument of the European Health-Related Quality of Life Measures. This was assessed at the last visit or at early discontinuation. RESULTS: The open-label extension-phase study included 337 patients (duloxetine, n = 222; routine care, n = 115). For the duloxetine group, mean age was 60.2 years, 61.3% were male, and 78.4% were white. For the routine-care group, mean age was 58.9 years, 60.0% were male, and 74.8% were white. Mean weight was 95.3 kg for both groups. None of the TEAEs occurred significantly more often in the duloxetine-treated group than in the routine-care-treated group. No TEAEs were reported by >10% of patients in the duloxetine group. The TEAEs reported by >10% of patients in the routine-care group included dizziness (11.3%), somnolence (13.0%), headache (10.4%), and vomiting (10.4%). No significant differences were found between treatment groups in the occurrence of serious AEs or in the number of patients discontinuing because of AEs. Duloxetine was significantly better than routine care on the bodily pain subscale of the SF-36 (mean change: 1.5 vs -4.1; P= 0.021) and on the EQ-5D (mean change: -0.00 vs -0.09; P = 0.001). CONCLUSIONS: Over 52 weeks of follow-up, treatment of these diabetic patients with duloxetine for peripheral neuropathic pain was associated with outcomes similar to, or significantly better than, that of routine care on most measures of tolerability, diabetic complications, and QOL.

Efficacy and safety of the novel α4ß2 neuronal nicotinic receptor partial agonist ABT-089 in adults with attention-deficit/hyperactivity disorder: a randomized, double-blind, placebo-controlled crossover study.

RATIONALE: α(4)ß(2) Neuronal nicotinic receptors (NNRs) are implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). OBJECTIVES: This study examined the efficacy and safety of the α(4)ß(2) NNR partial agonist ABT-089 versus placebo in adults with ADHD. METHODS: In this multicenter, randomized, double-blind, placebo-controlled crossover study, subjects received placebo followed by ABT-089 (2 mg once daily [QD], 5 mg QD, 15 mg QD, 40 mg QD, or 40 mg twice daily [BID]), or vice versa, in a 2 × 2 crossover design. Each treatment period was 4 weeks, separated by a 2-week washout period. The primary efficacy endpoint was the Conners' Adult ADHD Rating Scale-Investigator Rated (CAARS:Inv) total score at the end of each treatment period. Secondary outcomes based on clinician- and self-rated efficacy scales were evaluated. RESULTS: Of the 221 subjects enrolled, 171 met criteria for inclusion in the completers dataset for efficacy analyses. ABT-089 was superior to placebo on the CAARS:Inv total score at 40 mg QD and 40 mg BID (model-based least square mean difference from placebo: -4.33, P = 0.02; -3.02, P = 0.03, respectively). ABT-089 also demonstrated significant improvements on several secondary measures of efficacy. ABT-089 was generally safe and well tolerated. The most commonly reported adverse events (≥5%) for total ABT-089-treated subjects at rates higher than placebo were headache, upper respiratory tract infection, irritability, insomnia, and nasopharyngitis. CONCLUSIONS: In this phase 2 crossover study, the NNR partial agonist ABT-089, at doses of 40 mg QD and 40 mg BID, was efficacious and generally well tolerated in treatment of adults with ADHD.

The clinical importance of changes in the 0 to 10 numeric rating scale for worst, least, and average pain intensity: analyses of data from clinical trials of duloxetine in pain disorders.

UNLABELLED: Data on 1,700 patients pooled from 5 randomized, placebo-controlled duloxetine studies (3 in diabetic peripheral neuropathic pain and 2 in fibromyalgia) were analyzed to determine clinically important differences (CIDs) in the 0 to 10 Numeric Rating Scale-Pain Intensity (NRS-PI) for patient-reported "worst" and "least" pain intensity while validating the previously published level for "average" pain. The correspondence between the baseline-to-endpoint raw and percentage change in the NRS-PI for the worst, least, and average pain were compared to patients' perceived improvements at endpoint as measured by the 7-point Patient Global Impression of Improvement (PGI-I) scales. Stratification by baseline pain separated the raw but not the percent change scores. The PGI-I category of "much better" or above was our a priori definition of a CID. Cutoff points for the NRS-PI change scores were determined using a receiver operator curve analysis. A consistent relationship between the worst and average NRS-PI percent change and the PGI-I was demonstrated regardless of the study, pain type, age, sex, or treatment group with a reduction of approximately 34%. The least pain item CID was slightly higher at 41%. Raw change CID cutoff points were approximately -2, -2.5 and -3 for least, average, and worst pain respectively. PERSPECTIVE: We determined an anchor-based value for the change in the worst, least, and average pain intensity items of the Brief Pain Inventory that best represents a clinically important difference. Our findings support a standard definition of a clinically important difference in clinical trials of chronic-pain therapies.

Duloxetine for the management of diabetic peripheral neuropathic pain: response profile.

OBJECTIVE: The current analysis examines the response profile in patients receiving duloxetine for the management of diabetic peripheral neuropathic pain (DPNP). PATIENTS/DESIGN: Data were pooled from three double-blind, randomized, placebo-controlled 12-week acute therapy trials of patients with DPNP of at least 6 months' duration. Study 1 (N = 457) had treatment groups of duloxetine 20 mg once daily (QD), 60 mg QD, 60 mg twice daily (BID), and placebo; Studies 2 (N = 334) and 3 (N = 348) compared duloxetine 60 mg QD and 60 mg BID with placebo. The primary efficacy measure in each study was the weekly mean score of the 24-hour average pain severity. Treatment response was defined as a 30% reduction in pain severity, although some analyses were repeated using alternative response criteria (50% reduction, or 2-point reduction, in pain severity). RESULTS: Consistently across the three studies, response rates at endpoint were significantly higher among patients receiving duloxetine (60 mg QD or 60 mg BID) than among those receiving placebo, regardless of the chosen response criterion (30% reduction, 50% reduction, or 2-point reduction in weekly mean of 24-hour average pain severity). The proportion of patients achieving pain relief in the duloxetine treatment groups was significantly greater than that in the placebo group at Week 1 and at all subsequent study visits to the end of acute phase therapy. Using diary data (24-hour average pain severity) from the first 7 days of treatment, the first significant separation from placebo in pain severity reduction for duloxetine 60 mg QD occurred at Day 1 (Study 1), Day 2 (Study 2), and Day 4 (Study 3), while significant separation in response rates first occurred at Day 3 when using pooled data. CONCLUSIONS: Patients with DPNP receiving duloxetine 60 mg QD or 60 mg BID had significantly higher rates of treatment response, when compared with patients receiving placebo, regardless of the chosen response criterion. Response to duloxetine treatment tended to occur early in therapy.

Impact of disease characteristics on the efficacy of duloxetine in diabetic peripheral neuropathic pain.

OBJECTIVE: To evaluate the impact of baseline disease variables related to diabetes and diabetic neuropathy severity on efficacy and safety of duloxetine in the management of diabetic peripheral neuropathic pain. RESEARCH DESIGN AND METHODS: The impact of baseline conditions was evaluated using the data from three pooled placebo-controlled studies for combined duloxetine, doses of 60 mg q.d. and 60 mg b.i.d., versus placebo. The primary efficacy measure was the weekly mean of 24-h average pain severity, and night pain was the secondary measure. Safety and tolerability were assessed. RESULTS: There were no significant (P > 0.10) interactions of treatment by age (< 65 or > or = 65 years), type of diabetes (type 1 or type 2), duration of diabetes (median split < 9.18 or > or = 9.18 years), duration of diabetic neuropathy (< 2, 2 to < 6, or > or = 6 years), severity of diabetic neuropathy (baseline Michigan Neuropathy Screening Instrument score < 5 or > or = 5), baseline A1C level (median split < 7.6 or > or = 7.6%), or baseline insulin use (yes/no). Significant interactions for both pain measures were observed in baseline pain subgroups (Brief Pain Inventory average pain, > or = 6 and < 6). Duloxetine was more effective in the subgroup with more pain. No significant association was found between any other subgroups (P > 0.10). Significant interactions (P < 0.1) occurred with treatment-emergent adverse events when stratified by subgroups. CONCLUSIONS: Pain severity but not variables related to diabetes or neuropathy may predict the effects of duloxetine in diabetic peripheral neuropathic pain. The efficacy of duloxetine is related to the initial pain severity and is generalizable across a broad spectrum of diabetic patients, including those with the highest severity of diabetes or neuropathy.

An open-label 52-week clinical extension comparing duloxetine with routine care in patients with diabetic peripheral neuropathic pain.

OBJECTIVE: To assess the safety of duloxetine at a fixed-dose of 60 mg twice daily (BID) for up to 52 weeks, and compare duloxetine with routine care in the management of patients with diabetic peripheral neuropathic pain (DPNP). DESIGN AND INTERVENTIONS: Patients who completed a 13-week, randomized, double-blind, placebo-controlled acute therapy period were randomly reassigned in a 2:1 ratio to therapy with duloxetine 60 mg BID (N = 197) or routine care (N = 96) for an additional 52 weeks. PATIENTS: The trial included outpatients > or =18 years of age diagnosed with moderate to severe DPNP caused by type 1 or type 2 diabetes. RESULTS: Fourteen patients discontinued due to adverse events or death (11 [5.6%] duloxetine- and 3 [3.1%] routine care-treated patients). There were no significant therapy-group differences observed for patients with >/=1 serious adverse event. In total, 110 (55.8%) duloxetine- and 47 (49%) routine care-treated patients had > or =1 treatment-emergent adverse event (TEAE). The TEAE with a significant therapy-group difference, with patients in the duloxetine therapy group experiencing a higher percentage of events, was asthenia (11 [5.6%] duloxetine- vs no routine care-treated patients). Duloxetine did not appear to adversely affect lipid profiles, or nerve or eye function. There were no significant therapy-group differences observed in mean change in systolic blood pressure, weight, or electrocardiogram parameters. Significant therapy-group differences were observed in favor of duloxetine in the SF-36 physical component summary score, and subscale scores of physical functioning, bodily pain, mental health, and vitality. CONCLUSIONS: The results of this study provide support for the use of duloxetine in the long-term management of DPNP.

A double-blind, randomized multicenter trial comparing duloxetine with placebo in the management of diabetic peripheral neuropathic pain.

OBJECTIVE: Assess efficacy and safety of duloxetine, a selective serotonin and norepinephrine reuptake inhibitor, on the reduction of pain severity, in patients with diabetic peripheral neuropathic pain (DPNP). METHODS: This was a multicenter, parallel, double-blind, randomized, placebo-controlled trial that enrolled 348 patients with pain due to peripheral neuropathy caused by type 1 or type 2 diabetes mellitus. Patients (N = 116 per group) were randomly assigned to receive duloxetine 60 mg once daily (QD), duloxetine 60 mg twice daily (BID), or placebo, for 12 weeks. The primary outcome measure was the weekly mean score of 24-hour average pain severity evaluated on an 11-point Likert scale. Secondary outcome measures and safety were evaluated. RESULTS: Compared with placebo-treated patients, both duloxetine-treated groups improved significantly more (P < 0.001) on the 24-hour average pain score. Duloxetine demonstrated superiority to placebo in all secondary analyses of the primary efficacy measure. A significant treatment effect for duloxetine was observed in most secondary measures for pain. Discontinuations due to adverse events were more frequent in the duloxetine 60 mg BID- (12.1%) versus the placebo- (2.6%) treated group. Duloxetine showed no adverse effects on diabetic control, and both doses were safely administered and well tolerated. CONCLUSIONS: In this clinical trial, duloxetine 60 mg QD and duloxetine 60 mg BID were effective and safe in the management of DPNP.