Intranasal esketamine effectively treats treatment-resistant depression in adults regardless of baseline irritability.

OBJECTIVE: To evaluate the impact of baseline irritability on clinical outcomes in adults with treatment-resistant depression (TRD) treated with fixed or flexible doses of esketamine nasal spray plus a newly initiated oral antidepressant (ESK+AD) and to explore whether treatment with ESK affects irritability symptoms over time. METHODS: This was a post hoc analysis of pooled data from two 4-week, double-blind, phase 3 studies: TRANSFORM-1 (NCT02417064) and TRANSFORM-2 (NCT02418585). Adults with TRD (n = 560) were randomly assigned to ESK+AD or placebo nasal spray plus oral antidepressant (AD+PBO). Irritability was assessed with Item 6 of the 7-item Generalized Anxiety Disorder scale at screening and baseline. Changes in depression severity (Montgomery-Åsberg Depression Rating Scale [MADRS] total score) were evaluated by analysis of covariance (ANCOVA) models. Rates of MADRS response (≥50 % decrease from baseline total score) and remission (total score ≤ 12) were examined using multiple logistic regression models. RESULTS: Of 560 participants with TRD, 52.9 %, 23.2 %, and 23.9 % had high, low, and varying levels of irritability, respectively. No significant interaction between baseline irritability and treatment group was observed for change in MADRS total score, treatment response, or remission at day 28; numerically greater improvement was observed on all outcomes with ESK+AD versus AD+PBO at day 28 regardless of baseline irritability level. Percentages of patients reporting adverse events were similar across the three baseline irritability groups. LIMITATIONS: TRANSFORM-1 and TRANSFORM-2 were not designed to prospectively evaluate predetermined irritability outcomes. CONCLUSIONS: These post hoc results support efficacy of ESK+AD in patients with TRD, regardless of baseline irritability. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT02417064 (TRANSFORM-1), NCT02418585 (TRANSFORM-2).

Longitudinal Course of Adverse Events With Esketamine Nasal Spray: A Post Hoc Analysis of Pooled Data From Phase 3 Trials in Patients With Treatment-Resistant Depression.

Objective: To describe the tolerability of esketamine nasal spray based on the adverse event profile observed during treatment sessions occurring early and later over the course of treatment.Methods: In 2 long-term, phase 3 studies (NCT02493868, October 1, 2015-February 16, 2018; NCT02497287, September 30, 2015-October 28, 2017), patients with treatment-resistant major depressive disorder (per DSM-5) and nonresponse to ≥ 2 oral antidepressants received esketamine nasal spray (56 or 84 mg) twice weekly during a 4-week induction phase, weekly for weeks 5-8, and weekly or every 2 weeks thereafter as maintenance treatment, in conjunction with a new oral antidepressant. A post hoc analysis using descriptive statistics evaluated occurrence (incidence, frequency, severity) and recurrence (incidence and severity) of events of specific interest.Results: In patients treated with esketamine nasal spray plus a newly initiated oral antidepressant (n = 928), spontaneously reported adverse events of dizziness, nausea, sedation, vertigo, and increased blood pressure were more likely to recur after the first week of treatment if they occurred more frequently (twice > once > none) during the first week. The same pattern was observed when these events were assessed by structured instruments. Incidences of dizziness, dissociation, increased blood pressure, nausea, vertigo, and sedation were highest in week 1 of treatment (20.6%, 16.7%, 4.3%, 14.0%, 12.1%, and 3.8%, respectively) and decreased thereafter. Initial occurrences and subsequent recurrences of events were mostly mild or moderate in severity.Conclusions: Adverse events during treatment with esketamine nasal spray plus an oral antidepressant generally become less frequent with ongoing treatment, and the majority are mild or moderate in severity.Trial Registration: ClinicalTrials.gov identifiers: NCT02493868; NCT02497287.

Montgomery-Åsberg Depression Rating Scale factors in treatment-resistant depression at onset of treatment: Derivation, replication, and change over time during treatment with esketamine.

OBJECTIVE: Derive and confirm factor structure of the Montgomery-Åsberg Depression Rating Scale (MADRS) in patients with treatment-resistant depression (TRD) and evaluate how the factors evident at baseline change over 4 weeks of esketamine treatment. METHODS: Two similarly-designed, short-term TRANSFORM trials randomized adults to esketamine or matching placebo nasal spray, each with a newly-initiated oral antidepressant, for 4 weeks (TRANSFORM-1: N = 342 patients; TRANSFORM-2: N = 223 patients). The factor structure of MADRS item scores at baseline was determined by exploratory factor analysis in TRANSFORM-2 and corroborated by confirmatory factor analysis in TRANSFORM-1. Change in MADRS factor scores from baseline (day 1) to the end of the 28-day double-blind treatment phase of TRANSFORM-2 was analyzed using a mixed-effects model for repeated measures (MMRM). RESULTS: Three factors were identified based on analysis of MADRS items: Factor 1 labeled affective and anhedonic symptoms (apparent sadness, reported sadness, lassitude, inability to feel), Factor 2 labeled anxiety and vegetative symptoms (inner tension, reduced sleep, reduced appetite, concentration difficulties), and Factor 3 labeled hopelessness (pessimistic thoughts, suicidal thoughts). The three-factor structure observed in TRANSFORM-2 was verified in TRANSFORM-1. Treatment benefit at 24 h with esketamine versus placebo was observed on all 3 factors and continued throughout the 4-week double-blind treatment period. CONCLUSIONS: A three-factor structure for MADRS appears to generalize to TRD. All three factors improved over 4 weeks of treatment with esketamine nasal spray.

Relationship Between Dissociation and Antidepressant Effects of Esketamine Nasal Spray in Patients With Treatment-Resistant Depression.

BACKGROUND: In this post-hoc analysis, data from 2 positive, pivotal, phase 3 trials of esketamine nasal spray (ESK) in treatment-resistant depression (TRD)-short-term study (TRANSFORM-2) and maintenance study (SUSTAIN-1)-were analyzed to evaluate the relationship between dissociation and antidepressant effects of ESK. METHODS: Analysis by responder status, correlation analysis, and mediation analysis were performed to assess the relationships between peak Clinician Administered Dissociative States Scale (CADSS) scores after first (day 1) and last (day 25) ESK dose and change in Montgomery-Åsberg Depression Rating Scale (MADRS) total scores at the first (day 2) and last assessments (day 28) in TRANSFORM-2 and peak CADSS after first maintenance ESK dose and time to relapse in SUSTAIN-1 (only for mediation analysis). RESULTS: In TRANSFORM-2, the percentage of responders (>50% reduction in MADRS) at day 2 and day 28 did not significantly differ between patients who did vs did not manifest significant dissociation (peak CADSS scores >4 or ≤4, respectively) following the first ESK dose. Spearman correlation coefficients between dissociation and depression improvement were nonsignificant and close to zero. CADSS scores did not significantly mediate the reduction in MADRS at day 2 or 28 in TRANSFORM-2 or the time to depression relapse in SUSTAIN-1. The mean difference in MADRS between ESK and active-control arms persisted beyond day 2 without significant change across time, although the mean peak CADSS scores significantly decreased across consecutive doses and fewer patients experienced significant dissociation after the last ESK dose compared with the first. CONCLUSION: Within the dose range tested, the dissociative and antidepressant effects of ESK were not significantly correlated. TRIAL REGISTRATION: NCT02417064 (TRANSFORM-1); NCT02418585(TRANSFORM-2); NCT02493868 (SUSTAIN-1).

Efficacy and safety of esketamine nasal spray by sex in patients with treatment-resistant depression: findings from short-term randomized, controlled trials.

The objective of this analysis was to determine if there are sex differences with esketamine for treatment-resistant depression (TRD). Post hoc analyses of three randomized, controlled studies of esketamine in patients with TRD (TRANSFORM-1, TRANSFORM-2 [18-64 years], TRANSFORM-3 [≥ 65 years]) were performed. In each 4-week study, adults with TRD were randomized to esketamine or placebo nasal spray, each with a newly initiated oral antidepressant. Change from baseline to day 28 in Montgomery-Åsberg Depression Rating Scale (MADRS) total score was assessed by sex in pooled data from TRANSFORM-1/TRANSFORM-2 and separately in data from TRANSFORM-3 using a mixed-effects model for repeated measures. Use of hormonal therapy was assessed in all women, and menopausal status was assessed in women in TRANSFORM-1/TRANSFORM-2. Altogether, 702 adults (464 women) received ≥ 1 dose of intranasal study drug and antidepressant. Mean MADRS total score (SD) decreased from baseline to day 28, more so among patients treated with esketamine/antidepressant vs. antidepressant/placebo in both women and men: TRANSFORM-1/TRANSFORM-2 women-esketamine/antidepressant -20.3 (13.19) vs. antidepressant/placebo -15.8 (14.67), men-esketamine/antidepressant -18.3 (14.08) vs. antidepressant/placebo -16.0 (14.30); TRANSFORM-3 women-esketamine/antidepressant -9.9 (13.34) vs. antidepressant/placebo -6.9 (9.65), men-esketamine/antidepressant -10.3 (11.96) vs. antidepressant/placebo -5.5 (7.64). There was no significant sex effect or treatment-by-sex interaction (p > 0.35). The most common adverse events in esketamine-treated patients were nausea, dissociation, dizziness, and vertigo, each reported at a rate higher in women than men. The analyses support antidepressant efficacy and overall safety of esketamine nasal spray are similar between women and men with TRD. The TRANSFORM studies are registered at clinicaltrials.gov (identifiers: NCT02417064 (first posted 15 April 2015; last updated 4 May 2020), NCT02418585 (first posted 16 April 2015; last updated 2 June 2020), and NCT02422186 (first posted 21 April 2015; last updated 29 September 2021)).

Comparison of Long-Term Efficacy and Safety of Esketamine Nasal Spray Plus Oral Antidepressant in Younger Versus Older Patients With Treatment-Resistant Depression: Post-Hoc Analysis of SUSTAIN-2, a Long-Term Open-Label Phase 3 Safety and Efficacy Study.

BACKGROUND: Older, compared with younger, patients with treatment-resistant depression (TRD) typically have lower response and remission rates with poorer tolerability to antidepressant treatment. This post-hoc analysis compared outcomes following treatment with esketamine nasal spray (ESK) between younger (18-64 years) and older (≥65 years) patients with TRD. METHODS: SUSTAIN-2, an up to 1-year open-label safety and efficacy study of ESK plus an oral antidepressant, included patients with TRD either directly enrolled (≥18-year) or transferred from a phase 3 double-blind study, TRANSFORM-3 (≥65-year). Patients were treated in two phases: 4-week induction and 48-week optimization/maintenance. RESULTS: Younger (n = 624) and older (n = 178) patients had similar baseline characteristics except for hypertension history (21.5% versus 48.3%, respectively). Patients (younger versus older) had similar mean baseline Montgomery-Åsberg Depression Rating Scale (MADRS) total scores and mean (SD) reductions in MADRS total scores for induction (-18.0 [7.19] versus -18.1 [9.37]; p = 0.492 [t = 0.69, df = 701]) and optimization/maintenance (week 12) (-19.9 [7.03] versus -22.2 [9.50]; p = 0.265 [t = -1.12, df = 3470]) phases. Treatment-emergent adverse events (TEAEs) reported in younger versus older patients, respectively, were: induction, 86.1% versus 74.8%; optimization/maintenance, 86.8% versus 81.0%; serious TEAEs: induction, 2.2% versus 1.9%; optimization/maintenance, 6.7% versus 4.8%; TEAEs of increased blood pressure: induction, 6.9% versus 6.5%; optimization/maintenance, 7.1% versus 9.5%; and falls: induction, 0.3% versus 0.6%; optimization/maintenance, 0.2% versus 0.8%. Cognitive tests did not show clinically meaningful differences between the age groups. CONCLUSIONS: Although limited by the open-label design of SUSTAIN-2, this post-hoc analysis showed generally comparable improvement in depression between ESK-treated younger and older adult patients with TRD, with consistent safety outcomes.

The effect of esketamine in patients with treatment-resistant depression with and without comorbid anxiety symptoms or disorder.

BACKGROUND: Comorbid anxiety is generally associated with poorer response to antidepressant treatment. This post hoc analysis explored the efficacy of esketamine plus an antidepressant in patients with treatment-resistant depression (TRD) with or without comorbid anxiety. METHODS: TRANSFORM-2, a double-blind, flexible-dose, 4-week study (NCT02418585), randomized adults with TRD to placebo or esketamine nasal spray, each with a newly-initiated oral antidepressant. Comorbid anxiety was defined as clinically noteworthy anxiety symptoms (7-item Generalized Anxiety Disorder scale [GAD-7] score ≥10) at screening and baseline or comorbid anxiety disorder diagnosis at screening. Treatment effect based on change in Montgomery-Åsberg Depression Rating Scale (MADRS) total score, and response and remission were examined by presence/absence of comorbid anxiety using analysis of covariance and logistic regression models. RESULTS: Approximately 72% (162/223) of patients had baseline comorbid anxiety. Esketamine-treated patients with and without anxiety demonstrated significant reductions in MADRS (mean [SD] change from baseline at day 28: -21.0 [12.51] and -22.7 [11.98], respectively). Higher rates of response and remission, and a significantly greater decrease in MADRS score at day 28 were observed compared to antidepressant/placebo, regardless of comorbid anxiety (with anxiety: difference in LS means [95% CI] -4.2 [-8.1, -0.3]; without anxiety: -7.5 [-13.7, -1.3]). There was no significant interaction of treatment and comorbid anxiety (p = .371). Notably, in the antidepressant/placebo group improvement was similar in those with and without comorbid anxiety. CONCLUSION: Post hoc data support efficacy of esketamine plus an oral antidepressant in patients with TRD, regardless of comorbid anxiety.

Comments to Drs. Bahji, Vazquez, and Zarate.

In the absence of head-to-head studies directly comparing the efficacy of intranasal esketamine to that of intravenous ketamine, valid conclusions regarding comparative efficacy cannot be made based on the existing data from trials using markedly differing study designs and patient populations.

Relapse prevention in treatment-resistant major depressive disorder with rapid-acting antidepressants.

Major depressive disorder (MDD) is the leading cause of disability worldwide and reduces life expectancy. Achieving and sustaining remission from depression is challenging after initial improvement of an acute episode with an antidepressant, especially for patients whose depressive episodes have proven treatment-resistant in response to conventional antidepressant pharmacotherapy. While standard antidepressants are at least partly effective for the short-term treatment of acute depressive episodes of MDD, many patients relapse within 6 months of apparent clinical remission, with faster and higher rates observed in those with treatment-resistant depression (TRD). Efficacy of IV ketamine, a rapid-acting N-methyl d-aspartate (NMDA) receptor antagonist, in maintaining antidepressant effect was suggested in a few small, single center, open-label studies and case series. More recently, maintenance of antidepressant effects beyond the initial acute (induction) treatment period has been shown with esketamine nasal spray, an enantiomer of ketamine, in conjunction with an oral antidepressant in three phase 2/3 registration studies (SYNAPSE, SUSTAIN-1, SUSTAIN-2) of adult patients with TRD. In these studies the maintenance of efficacy of an intermittently-dosed esketamine treatment regimen was established in which twice-weekly dose administration during a 4-week induction period was followed initially by weekly administration and later by either weekly or every-other-week administration. During long-term maintenance therapy the antidepressant effect persisted in most patients with this regimen, despite their history of being resistant to conventional antidepressants prior to entering esketamine studies. These data suggest that the neurobiological changes induced by initial esketamine treatment, which putatively underlie its antidepressant effect, can be maintained using repeated administration.

Esketamine Nasal Spray Plus Oral Antidepressant in Patients With Treatment-Resistant Depression: Assessment of Long-Term Safety in a Phase 3, Open-Label Study (SUSTAIN-2).

OBJECTIVE: To evaluate long-term safety and efficacy of esketamine nasal spray plus a new oral antidepressant (OAD) in patients with treatment-resistant depression (TRD). METHODS: This phase 3, open-label, multicenter, long-term (up to 1 year) study was conducted between October 2015 and October 2017. Patients (≥ 18 years) with TRD (DSM-5 diagnosis of major depressive disorder and nonresponse to ≥ 2 OAD treatments) were enrolled directly or transferred from a short-term study (patients aged ≥ 65 years). Esketamine nasal spray (28-mg, 56-mg, or 84-mg) plus new OAD was administered twice a week in a 4-week induction (IND) phase and weekly or every-other-week for patients who were responders and entered a 48-week optimization/maintenance (OP/MAINT) phase. RESULTS: Of 802 enrolled patients, 86.2% were direct-entry and 13.8% were transferred-entry; 580 (74.5%) of 779 patients who entered the IND phase completed the phase, and 150 (24.9%) of 603 who entered the OP/MAINT phase completed the phase. Common treatment-emergent adverse events (TEAEs) were dizziness (32.9%), dissociation (27.6%), nausea (25.1%), and headache (24.9%). Seventy-six patients (9.5%) discontinued esketamine due to TEAEs. Fifty-five patients (6.9%) experienced serious TEAEs. Most TEAEs occurred on dosing days, were mild or moderate in severity, and resolved on the same day. Two deaths were reported; neither was considered related to esketamine. Cognitive performance generally either improved or remained stable postbaseline. There was no case of interstitial cystitis or respiratory depression. Treatment-emergent dissociative symptoms were transient and generally resolved within 1.5 hours postdose. Montgomery-Åsberg Depression Rating Scale total score decreased during the IND phase, and this reduction persisted during the OP/MAINT phase (mean [SD] change from baseline of respective phase to endpoint: IND, -16.4 [8.76]; OP/MAINT, 0.3 [8.12]). CONCLUSIONS: Long-term esketamine nasal spray plus new OAD therapy had a manageable safety profile, and improvements in depression appeared to be sustained in patients with TRD. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02497287.

Efficacy and Safety of Esketamine Nasal Spray Plus an Oral Antidepressant in Elderly Patients With Treatment-Resistant Depression-TRANSFORM-3.

BACKGROUND: Elderly patients with major depression have a poorer prognosis, are less responsive to treatment, and show greater functional decline compared with younger patients, highlighting the need for effective treatment. METHODS: This phase 3 double-blind study randomized patients with treatment-resistant depression (TRD) ≥65 years (1:1) to flexibly dosed esketamine nasal spray and new oral antidepressant (esketamine/antidepressant) or new oral antidepressant and placebo nasal spray (antidepressant/placebo). The primary endpoint was change in the Montgomery-Åsberg Depression Rating Scale (MADRS) from baseline to day 28. Analyses included a preplanned analysis by age (65-74 versus ≥75 years) and post-hoc analyses including age at depression onset. RESULTS: For the primary endpoint, the median-unbiased estimate of the treatment difference (95% CI) was -3.6 (-7.20, 0.07); weighted combination test using MMRM analyses z = 1.89, two-sided p = 0.059. Adjusted mean (95% CI) difference for change in MADRS score between treatment groups was -4.9 (-8.96, -0.89; t = -2.4, df = 127; two-sided nominal p = 0.017) for patients 65 to 74 years versus -0.4 (-10.38, 9.50; t = -0.09, two-sided nominal p = 0.930) for those ≥75 years, and -6.1 (-10.33, -1.81; t = -2.8, df = 127; two-sided nominal p = 0.006) for patients with depression onset <55 years and 3.1 (-4.51, 10.80; t = 0.8, two-sided nominal p = 0.407) for those ≥55 years. Patients who rolled over into the long-term open-label study showed continued improvement with esketamine following 4 additional treatment weeks. CONCLUSIONS: Esketamine/antidepressant did not achieve statistical significance for the primary endpoint. Greater differences between treatment arms were seen for younger patients (65-74 years) and patients with earlier onset of depression (<55 years).

Efficacy and Safety of Fixed-Dose Esketamine Nasal Spray Combined With a New Oral Antidepressant in Treatment-Resistant Depression: Results of a Randomized, Double-Blind, Active-Controlled Study (TRANSFORM-1).

BACKGROUND: About one-third of patients with depression fail to achieve remission despite treatment with multiple antidepressants and are considered to have treatment-resistant depression. METHODS: This Phase 3, double-blind, multicenter study enrolled adults with moderate-to-severe depression and nonresponse to ≥2 antidepressants in the current depression episode. Eligible patients (N = 346) were randomized (1:1:1) to twice-weekly nasal spray treatment (esketamine [56 or 84 mg] or placebo) plus a newly initiated, open-label, oral antidepressant taken daily for 4 weeks. The primary efficacy endpoint was change from baseline to day 28 in the Montgomery-Asberg Depression Rating Scale total score, performed by blinded, remote raters. Based on the predefined statistical testing sequence, esketamine 84 mg/antidepressant had to be significant for esketamine 56 mg/antidepressant to be formally tested. RESULTS: Statistical significance was not achieved with esketamine 84 mg/antidepressant compared with antidepressant/placebo (least squares [LS] means difference [95% CI]: -3.2 [-6.88, 0.45]; 2-sided P value = .088). Although esketamine 56 mg/antidepressant could not be formally tested, the LS means difference was -4.1 [-7.67, -0.49] (nominal 2-sided P value = .027). The most common (>20%) adverse events reported for esketamine/antidepressant were nausea, dissociation, dizziness, vertigo, and headache. CONCLUSIONS: Statistical significance was not achieved for the primary endpoint; nevertheless, the treatment effect (Montgomery-Asberg Depression Rating Scale) for both esketamine/antidepressant groups exceeded what has been considered clinically meaningful for approved antidepressants vs placebo. Safety was similar between esketamine/antidepressant groups and no new dose-related safety concerns were identified. This study provides supportive evidence for the safety and efficacy of esketamine nasal spray as a new, rapid-acting antidepressant for patients with treatment-resistant depression. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02417064.

Efficacy of Esketamine Nasal Spray Plus Oral Antidepressant Treatment for Relapse Prevention in Patients With Treatment-Resistant Depression: A Randomized Clinical Trial.

Importance: Controlled studies have shown short-term efficacy of esketamine for treatment-resistant depression (TRD), but long-term effects remain to be established. Objective: To assess the efficacy of esketamine nasal spray plus an oral antidepressant compared with an oral antidepressant plus placebo nasal spray in delaying relapse of depressive symptoms in patients with TRD in stable remission after an induction and optimization course of esketamine nasal spray plus an oral antidepressant. Design, Setting, and Participants: In this phase 3, multicenter, double-blind, randomized withdrawal study conducted from October 6, 2015, to February 15, 2018, at outpatient referral centers, 705 adults with prospectively confirmed TRD were enrolled; 455 entered the optimization phase and were treated with esketamine nasal spray (56 or 84 mg) plus an oral antidepressant. After 16 weeks of esketamine treatment, 297 who achieved stable remission or stable response entered the randomized withdrawal phase. Interventions: Patients who achieved stable remission and those who achieved stable response (without remission) were randomized 1:1 to continue esketamine nasal spray or discontinue esketamine treatment and switch to placebo nasal spray, with oral antidepressant treatment continued in each group. Main Outcomes and Measures: Time to relapse was examined in patients who achieved stable remission, as assessed using a weighted combination log-rank test. Results: Among the 297 adults (mean age [SD], 46.3 [11.13] years; 197 [66.3%] female) who entered the randomized maintenance phase, 176 achieved stable remission; 24 (26.7%) in the esketamine and antidepressant group and 39 (45.3%) in the antidepressant and placebo group experienced relapse (log-rank P = .003, number needed to treat [NNT], 6). Among the 121 who achieved stable response, 16 (25.8%) in the esketamine and antidepressant group and 34 (57.6%) in the antidepressant and placebo group experienced relapse (log-rank P < .001, NNT, 4). Esketamine and antidepressant treatment decreased the risk of relapse by 51% (hazard ratio [HR], 0.49; 95% CI, 0.29-0.84) among patients who achieved stable remission and 70% (HR, 0.30; 95% CI, 0.16-0.55) among those who achieved stable response compared with antidepressant and placebo treatment. The most common adverse events reported for esketamine-treated patients after randomization were transient dysgeusia, vertigo, dissociation, somnolence, and dizziness (incidence, 20.4%-27.0%), each reported in fewer patients (<7%) treated with an antidepressant and placebo. Conclusions and Relevance: For patients with TRD who experienced remission or response after esketamine treatment, continuation of esketamine nasal spray in addition to oral antidepressant treatment resulted in clinically meaningful superiority in delaying relapse compared with antidepressant plus placebo. Trial Registration: ClinicalTrials.gov identifier: NCT02493868.

Efficacy and Safety of Flexibly Dosed Esketamine Nasal Spray Combined With a Newly Initiated Oral Antidepressant in Treatment-Resistant Depression: A Randomized Double-Blind Active-Controlled Study.

OBJECTIVE: About one-third of patients with depression fail to achieve remission despite treatment with multiple antidepressants. This study compared the efficacy and safety of switching patients with treatment-resistant depression from an ineffective antidepressant to flexibly dosed esketamine nasal spray plus a newly initiated antidepressant or to a newly initiated antidepressant (active comparator) plus placebo nasal spray. METHODS: This was a phase 3, double-blind, active-controlled, multicenter study conducted at 39 outpatient referral centers. The study enrolled adults with moderate to severe nonpsychotic depression and a history of nonresponse to at least two antidepressants in the current episode, with one antidepressant assessed prospectively. Confirmed nonresponders were randomly assigned to treatment with esketamine nasal spray (56 or 84 mg twice weekly) and an antidepressant or antidepressant and placebo nasal spray. The primary efficacy endpoint, change from baseline to day 28 in Montgomery-Åsberg Depression Rating Scale (MADRS) score, was assessed by a mixed-effects model using repeated measures. RESULTS: Of 435 patients screened, 227 underwent randomization and 197 completed the 28-day double-blind treatment phase. Change in MADRS score with esketamine plus antidepressant was significantly greater than with antidepressant plus placebo at day 28 (difference of least square means=-4.0, SE=1.69, 95% CI=-7.31, -0.64); likewise, clinically meaningful improvement was observed in the esketamine plus antidepressant arm at earlier time points. The five most common adverse events (dissociation, nausea, vertigo, dysgeusia, and dizziness) all were observed more frequently in the esketamine plus antidepressant arm than in the antidepressant plus placebo arm; 7% and 0.9% of patients in the respective treatment groups discontinued study drug because of an adverse event. Adverse events in the esketamine plus antidepressant arm generally appeared shortly after dosing and resolved by 1.5 hours after dosing. CONCLUSIONS: Current treatment options for treatment-resistant depression have considerable limitations in terms of efficacy and patient acceptability. Esketamine is expected to address an unmet medical need in this population through its novel mechanism of action and rapid onset of antidepressant efficacy. The study supports the efficacy and safety of esketamine nasal spray as a rapidly acting antidepressant for patients with treatment-resistant depression.