Psychiatry · Clinical trials
Treatment-Resistant Depression Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About treatment-resistant depression — and why its trials are hard
Treatment-resistant depression (TRD) is commonly defined as major depressive disorder that has failed to respond to at least two adequate trials of antidepressants of adequate dose and duration in the current episode. It represents a large, high-burden subpopulation with elevated suicide risk, disability, and healthcare costs. The landmark advance was esketamine (Spravato), the S-enantiomer of ketamine and an NMDA-receptor antagonist delivered as a nasal spray, first FDA-approved in 2019 in combination with an oral antidepressant and later approved as monotherapy. It offers rapid antidepressant effects on the Montgomery-Asberg Depression Rating Scale (MADRS), a shift from the weeks-long onset of conventional agents. Administration occurs under a REMS program with post-dose monitoring for dissociation and sedation. Beyond esketamine, TRD care includes augmentation (atypical antipsychotics, lithium), electroconvulsive therapy, and transcranial magnetic stimulation. The pathway has also seen notable failures, most prominently the NMDA-modulator rapastinel, whose Phase 3 program did not separate from placebo, underscoring the difficulty of translating rapid-acting glutamatergic mechanisms into reproducible pivotal results.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Esketamine (Spravato) | 2019 | Adults with TRD; intranasal, with an oral antidepressant, administered under REMS with monitoring (monotherapy approved later, 2025) | TRANSFORM-2 Phase 3 randomized double-blind active-controlled trial | MADRS total score change from baseline at Day 28 | MADRS improvement favoring esketamine plus antidepressant vs placebo plus antidepressant by 4.0 points (95% CI approx -7.3 to -0.6) |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in treatment-resistant depression development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Rapastinel — Phase 3 adjunctive TRD program (RAP-MD-01, -02, -03); endpoint MADRS change from baseline | Failed in 2019 to separate from placebo on MADRS and key secondary endpoints across the pivotal studies, ending development | High placebo response, possible inadequate NMDA target engagement/exposure with the IV bolus, and lack of the dissociative effects thought to accompany efficacy |
| Esketamine fixed-dose arm (TRANSFORM-1) — TRANSFORM-1 Phase 3 (fixed 56 mg and 84 mg doses); endpoint MADRS change at Day 28 | Did not achieve statistical significance on the primary endpoint for the pre-specified dose comparison, though numerical improvement was seen | Statistical hierarchy/testing sequence and variability; the flexible-dose TRANSFORM-2 provided the positive pivotal evidence |
Choosing the right endpoint
Primary endpoints that matter in treatment-resistant depression trials
- MADRS (Montgomery-Asberg Depression Rating Scale) — 10-item clinician scale; primary efficacy endpoint in modern TRD trials including esketamine
- MADRS remission (score <=12) / response (>=50% reduction) — Categorical outcomes used as key secondary endpoints
- SDS (Sheehan Disability Scale) — Functional impairment measure, common secondary endpoint in TRD
- CGI-S / CGI-I — Global clinician-rated severity and improvement used as supportive measures
How iNGENū runs treatment-resistant depression trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Treatment-Resistant Depression clinical trials — FAQs
What is the first FDA-approved drug for treatment-resistant depression?
How is TRD typically defined?
Why did rapastinel fail despite a promising mechanism?
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