SUSTAIN-2 (NCT02497287) was an open-label, phase III trial evaluating the safety of esketamine (ESK) nasal spray plus a newly initiated oral antidepressant (AD) for up to 1 year in adults with treatment-resistant depression (TRD). ESK is a schedule III drug that acts via glutamate receptor modulation. ESK is rapidly cleared from the plasma, and with intermittent dosing there is no accumulation. Thus, no withdrawal syndrome is expected. The current analysis assessed potential withdrawal symptoms in patients who discontinued ESK after long-term, intermittent use. In the absence of a glutamatergic-specific withdrawal scale, the Physicians Withdrawal Checklist1 (PWC-20) was used. The PWC-20 was designed to assess new or worsening benzodiazepine-like discontinuation symptoms after stopping non-SSRI anxiolytics.

ESK nasal spray was administered two times per week during a 4-week induction phase (IND). Responders entered the optimization/maintenance phase (O/M) where ESK nasal spray was dosed either weekly or every two weeks for up to 48 weeks. Patients entered a 4-week follow up period (F/U) after discontinuation from either phase, during which continuation of the AD was recommended. PWC-20 assessments were conducted at the last ESK dosing (endpoint of IND or O/M) and at weeks 1, 2 and 4 of F/U. Symptoms were rated using a 0-3-point scale (Not present = 0, Mild = 1, Moderate = 2, Severe = 3). To account for worsening of underlying depression, subset calculations were performed for depressive symptoms (PWC-DS: loss of appetite; anxiety or nervousness; irritability; dysphoric mood or depression; insomnia; fatigue, lethargy or lack of energy; restlessness or agitation; headaches; muscle aches or stiffness; weakness; difficulty concentrating or remembering; depersonalization-derealization) and withdrawal symptoms (PWC-WS: nausea and/or vomiting; diarrhea; poor coordination; diaphoresis; tremor or tremulousness; dizziness or light-headedness; increased acuity of sound, smell, or touch; paresthesias).

Data on 357 patients entering F/U were included in the analysis (91 completed treatment during the IND phase and 141 were treated during O/M). The mean (SD) PWC-20 total scores (range 0-60) at treatment endpoint, Week 1, 2 and 4 were 7.2 (6.8), 7.5(7.0), 7.4 (7.1) and 7.2 (6.9), respectively. At these same assessment times, mean PWC-WS scores (range 0-24) were 0.9 (1.7), 1.0 (1.7), 1.0 (1.8), and 0.9 (1.8). Mean PWC-DS scores (range 0-36) were 6.3 (5.6), 6.5 (5.7), 6.5 (5.8), and 6.3 (5.7), respectively. Complete analysis of data from the entire SUSTAIN-2 dataset will be presented.

No indication of drug-specific withdrawal symptoms was seen after stopping up to 1-year of intermittent treatment with ESK nasal spray for TRD.

Janssen Research and Development