BACKGROUND: In patients with treatment resistant depression (TRD), the ESCAPE-TRD study showed esketamine nasal spray was superior to quetiapine extended release. AIMS: To determine the robustness of the ESCAPE-TRD results and confirm the superiority of esketamine nasal spray over quetiapine extended release. METHOD: ESCAPE-TRD was a randomised, open-label, rater-blinded, active-controlled phase IIIb trial. Patients had TRD (i.e. non-response to two or more antidepressive treatments within a major depressive episode). Patients were randomised 1:1 to flexibly dosed esketamine nasal spray or quetiapine extended release, while continuing an ongoing selective serotonin reuptake inhibitor/serotonin norepinephrine reuptake inhibitor. The primary end-point was achieving a Montgomery-Åsberg Depression Rating Scale score of ≤10 at Week 8, while the key secondary end-point was remaining relapse free through Week 32 after achieving remission at Week 8. Sensitivity analyses were performed on these end-points by varying the definition of remission based on timepoint, threshold and scale. RESULTS: Of 676 patients, 336 were randomised to esketamine nasal spray and 340 to quetiapine extended release. All sensitivity analyses on the primary and key secondary end-point favoured esketamine nasal spray over quetiapine extended release, with relative risks ranging from 1.462 to 1.737 and from 1.417 to 1.838, respectively (all CONCLUSION: Esketamine nasal spray consistently demonstrated significant superiority over quetiapine extended release using all pre-specified definitions for remission and relapse. Sensitivity analyses supported the conclusions of the primary ESCAPE-TRD analysis and demonstrated robustness of the results.