From Resistance to Redesign-The Emerging Logic of Hybrid Care in Treatment-Resistant Depression.

Background/

Objectives

Treatment-resistant depression (TRD) remains one of the most urgent unmet needs in psychiatry, while its therapeutic pipeline is evolving rapidly. To characterize current development trajectories, we conducted a registry-anchored mapping of interventional trials in adults with major depressive disorder and treatment resistance (MDD-TRD), with the aim of defining the distribution of intervention types, endpoint choices, and key design features across the active trial landscape.

Methods

We systematically searched ClinicalTrials.gov, the EU Clinical Trials Information System, and ISRCTN for interventional MDD-TRD trials registered up to 18 September 2025. After data cleaning and cross-registry deduplication, 237 unique trials were retained. Interventions were categorized through a taxonomy distinguishing device-based neuromodulation, pharmacological strategies, biologic/novel agents, multimodal non-digital combinations, digital-hybrid programs, psychotherapy, and lifestyle interventions, with classification anchored on structured registry intervention tags and whole-word matching across title and intervention text. Primary endpoints were flagged as standard when they explicitly referenced the Montgomery-Åsberg Depression Rating Scale or Hamilton Depression Rating Scale. We also examined developmental phase, sample size, and recurrent methodological features.

Results

Device-based neuromodulation accounted for the largest share of the active pipeline (114/237, 48.1%), followed by pharmacological strategies (86/237, 36.3%), biologic/novel agents (16/237, 6.8%), and multimodal non-digital combinations (11/237, 4.6%). Digital-hybrid programs represented a small but distinctive stratum (5/237, 2.1%), with the remaining records comprising lifestyle interventions (3/237, 1.3%) and psychotherapy (2/237, 0.8%). Standard clinician-rated primary endpoints were used in 63.3% of studies. Trial development was concentrated in mid-phase designs, whereas sample sizes were generally modest (median 49; interquartile range, 19-87). Across modalities, increasing attention was directed to durability of response, functioning, and patient-reported outcomes, with adaptive and enrichment-based designs appearing with greater frequency.

Conclusions

The contemporary TRD trial ecosystem is structured around two co-active developmental tracks-device-based neuromodulation and pharmacology with novel mechanisms-accompanied by a smaller but measurably expanding biologic/novel stratum and a still-marginal digital-hybrid presence. This registry-based mapping provides a near-real-time overview of the field and may support future harmonization of trial endpoints and design standards.