Doubly randomized delayed-start design for enrichment studies with responders or nonresponders

Enrichment designs using placebo nonresponders

Enrichment designs that select placebo nonresponders have gained much attention during the last years in areas with high placebo response rates, eg, in depression. Proposals were made that re-randomize patients who did not respond to placebo during a first study phase as the sequential parallel design (SPD). This design uses in a second phase an enriched patient population where the treatment effect is expected to be more pronounced. This may be problematic if an effect in the overall population is claimed. Proposals were made to combine the treatment effects in the overall population from study phase 1 and the enriched population from study phase 2, alleviating but not solving the issue of a potential selection bias. This paper shows how this bias corresponding to the effect difference between the overall population and the enriched population depends on the variability of a potential subject-by-treatment interaction. Sample sizes are given, which lead to a significant result in the combining test with a given probability if actually the average effect in the overall population is zero. If, on the other hand, no subject-by-treatment interaction is given, the enrichment is shown to be inefficient. We conclude that enrichment designs using placebo nonresponders are not able to claim a positive average effect in the overall population if a subject-by-treatment interaction cannot be excluded. It cannot be used to demonstrate positive efficacy in the overall population in a pivotal phase III trial but may be used in early phases to demonstrate varying treatment effects between patients.

Efficacy and Safety of Intranasal Esketamine Adjunctive to Oral Antidepressant Therapy in Treatment-Resistant Depression: A Randomized Clinical Trial

Importance

Approximately one-third of patients with major depressive disorder (MDD) do not respond to available antidepressants.

Objective

To assess the efficacy, safety, and dose-response of intranasal esketamine hydrochloride in patients with treatment-resistant depression (TRD).

Design, Setting, and Participants

This phase 2, double-blind, doubly randomized, delayed-start, placebo-controlled study was conducted in multiple outpatient referral centers from January 28, 2014, to September 25, 2015. The study consisted of 4 phases: (1) screening, (2) double-blind treatment (days 1-15), composed of two 1-week periods, (3) optional open-label treatment (days 15-74), and (4) posttreatment follow-up (8 weeks). One hundred twenty-six adults with a DSM-IV-TR diagnosis of MDD and history of inadequate response to 2 or more antidepressants (ie, TRD) were screened, 67 were randomized, and 60 completed both double-blind periods. Intent-to-treat analysis was used in evaluation of the findings.

Interventions

In period 1, participants were randomized (3:1:1:1) to placebo (n = 33), esketamine 28 mg (n = 11), 56 mg (n = 11), or 84 mg (n = 12) twice weekly. In period 2, 28 placebo-treated participants with moderate-to-severe symptoms were rerandomized (1:1:1:1) to 1 of the 4 treatment arms; those with mild symptoms continued receiving placebo. Participants continued their existing antidepressant treatment during the study. During the open-label phase, dosing frequency was reduced from twice weekly to weekly, and then to every 2 weeks.

Main Outcomes and Measures

The primary efficacy end point was change from baseline to day 8 (each period) in the Montgomery-Åsberg Depression Rating Scale (MADRS) total score.

Results

Sixty-seven participants (38 women, mean [SD] age, 44.7 [10.0] years) were included in the efficacy and safety analyses. Change (least squares mean [SE] difference vs placebo) in MADRS total score (both periods combined) in all 3 esketamine groups was superior to placebo (esketamine 28 mg: -4.2 [2.09], P = .02; 56 mg: -6.3 [2.07], P = .001; 84 mg: -9.0 [2.13], P < .001), with a significant ascending dose-response relationship (P < .001). Improvement in depressive symptoms appeared to be sustained (-7.2 [1.84]) despite reduced dosing frequency in the open-label phase. Three of 56 (5%) esketamine-treated participants during the double-blind phase vs none receiving placebo and 1 of 57 participants (2%) during the open-label phase had adverse events that led to study discontinuation (1 event each of syncope, headache, dissociative syndrome, and ectopic pregnancy).

Conclusions and Relevance

In this first clinical study to date of intranasal esketamine for TRD, antidepressant effect was rapid in onset and dose related. Response appeared to persist for more than 2 months with a lower dosing frequency. Results support further investigation in larger trials.

Trial Registration

clinicaltrials.gov identifier: NCT01998958.

Efficacy and safety of an adjunctive mGlu2 receptor positive allosteric modulator to a SSRI/SNRI in anxious depression

This phase 2a, randomized, multicenter, double-blind, proof-of-concept study was designed to evaluate, efficacy, safety and tolerability of JNJ-40411813/ADX71149, a novel metabotropic glutamate 2 receptor positive allosteric modulator as an adjunctive treatment for major depressive disorder (MDD) with significant anxiety symptoms. Eligible patients (18-64 years) had a DSM-IV diagnosis of MDD, Hamilton Depression Rating Scale-17 (HDRS17) score of ≥ 18, HDRS17 anxiety/somatization factor score of ≥ 7, and an insufficient response to current treatment with a selective serotonin reuptake inhibitor or serotonin-norepinephrine reuptake inhibitor. The doubly-randomized, 8-week double-blind treatment phase was comprised of two 4-week periods, from which a combined test statistic was generated, with pre-determined weights assigned to each of the 2 treatment periods. Period 1: patients (n=121) were randomly assigned (1:1) to JNJ-40411813 (n=62; 50mg to 150 mg b.i.d, flexibly dosed) or placebo (n=59); Period 2: placebo-treated patients (n=22) who continued to meet entry severity criteria were re-randomized (1:1) to JNJ-40411813 or placebo, while other patients underwent sham re-randomization and continued on their same treatment. Of 121 randomized patients, 100 patients (82.6%) were completers. No efficacy signal was detected on the primary endpoint, the 6-item Hamilton Anxiety Subscale (HAM-A6, p=0.51). Efficacy signals (based on prespecified 1-sided p<0.20) were evident on several secondary outcome measures of both depression (HDRS17 total score, 6-item subscale of HDRS17 assessing core depressive symptoms [HAM-D6], and Inventory of Depressive Symptomatology [IDS-C30]) and anxiety (HDRS17 anxiety/somatization factor, IDS-C30 anxiety subscale). Although well-tolerated, the results do not suggest efficacy for JNJ-40411813 as an adjunctive treatment for patients with MDD with significant anxious symptoms in the dose range studied.

On clinical trials with a high placebo response rate

The basic problem that causes the frequent failure of a standard randomized parallel placebo-controlled clinical trial with a high placebo response rate is the underestimation of the treatment effect by the observed relative treatment difference. A two-period sequential parallel enrichment design has been proposed where the first period is a standard parallel design and at the end of the first period, the placebo non-responders are identified and re-randomized in the second period. Based on such a design, available methods have primarily focused on testing either the first period treatment null hypothesis or the global null hypothesis defined as the joint period 1 and period 2 treatment effect null hypothesis by a test statistic which is either derived from a combined statistic or defined directly as a weighted z-score where the weights are functions of some population and design parameters satisfying certain power optimality criterion. However, in some cases, it is not clear what their combined statistics are estimating and in others, the combined statistics are estimating the apparent treatment effect; but generally, there is no discussion of the need to provide a proper assessment of the treatment effect for the intended study population. It should be clear that an appropriate assessment of the treatment effect for the intended study population is critical for the benefit/risk analysis as well as the proper dosage recommendation. Any benefit/risk analysis and dosage recommendation that are based on an apparent treatment effect from a standard parallel design such as the first period of a sequential parallel enrichment design tend to underestimate the benefit/risk ratio which in turn may lead to overdosing recommendation. It is the purpose of this paper to introduce the concept of an adjusted treatment effect which is derived by adjusting the apparent treatment effect from the first period of a sequential parallel enrichment design with information from the second period subject to a consistency condition. The adjustment properly compensates for the high placebo response rate. It is proposed that this adjusted treatment effect should be used to assess the treatment effect for the intended study population and should be the basis for the benefit/risk analysis and the dosage recommendation.