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Adding ABX-002 to existing antidepressant treatment for major depression

A Phase 2 Randomized, Double-Blind, Placebo-Controlled Study of ABX-002 for the Adjunctive Treatment of Major Depressive Disorder

Phase 2 Interventional Autobahn Therapeutics, Inc. · NCT06633016

This study is testing if adding a new treatment called ABX-002 to current antidepressants can help adults with major depression feel better when their existing medications aren't working well enough.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment230 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorAutobahn Therapeutics, Inc. Industry-sponsored
Locations50 sites (Birmingham, Alabama and 49 other locations)
Trial IDNCT06633016 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to evaluate the efficacy of ABX-002 as an adjunctive treatment for adults suffering from moderate to severe major depressive disorder who have not adequately responded to their current antidepressant therapy. The study is designed as a double-blind, placebo-controlled, Phase 2 trial, where participants will be randomly assigned to receive either ABX-002 or a placebo in addition to their ongoing antidepressant treatment. The trial will consist of a screening phase, a 42-day treatment period, and a 2-week safety follow-up period to monitor any adverse effects. The primary focus is to determine if the addition of ABX-002 can significantly improve depression symptoms compared to placebo.

Who should consider this trial

Good fit: Ideal candidates are adults diagnosed with major depressive disorder who have been on a stable dose of an antidepressant for at least 6 weeks but have not experienced sufficient relief from their symptoms.

Not a fit: Patients who have not been compliant with their current antidepressant regimen or who have not met the criteria for major depressive disorder may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new option for patients with major depressive disorder who have not responded well to existing antidepressants.

How similar studies have performed: Other studies exploring adjunctive treatments for major depressive disorder have shown promise, but the specific approach with ABX-002 is novel.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Meets the DSM-5 criteria for Major Depressive Disorder, with a current major depressive episode duration of \> 6 weeks and ≤ 18 months.
* A score of ≤ 22 (midrange mild/moderate) on the Hamilton Anxiety Rating Scale.
* Montgomery-Asberg Depression Rating Scale total score of \> 24 \[indicating moderate to severe depression\] at Screening and at Baseline.
* Subject is compliantly using a single selective serotonin reuptake inhibitors / serotonin norepinephrine reuptake inhibitor antidepressant for at least 6 weeks for their current episode of depression, with an adequate dose, and with an inadequate response as defined by the Antidepressant Treatment Response Questionnaire. The dosage of the current antidepressant must have been stable for the past 4 weeks, and the dosage and specific antidepressant used should remain the same from Screening through the end of the Follow-up Period.

Exclusion Criteria:

Note: History implies lifetime history, unless otherwise specified

* History of schizophrenia or other psychotic disorder, major depressive disorder with psychotic features or concomitant DSM-5 depressive disorders, bipolar I or II disorder, cyclothymic disorder, delirium, dementia, amnestic disorder, or cognitive disorder.
* Current diagnosis or active symptoms within the last 2 years of obsessive-compulsive disorder, posttraumatic stress disorder, panic disorder, or eating disorder, according to DSM-5 criteria.
* Primary diagnosis of borderline, antisocial, paranoid, schizoid, schizotypal, or histrionic personality disorder, according to DSM-5 criteria. Current or history within the last 2 years of self-injurious behavior is exclusionary.
* Has failed more than 2 single selective serotonin reuptake inhibitors / serotonin norepinephrine reuptake inhibitor antidepressant treatments, including the current serotonin reuptake inhibitors / serotonin norepinephrine reuptake inhibitor, during the current depressive episode, despite an adequate dose (per Antidepressant Treatment Response Questionnaire) and duration (at least 6 weeks).
* Failure to respond to triiodothyronine or thyroxine augmentation for the treatment of depression.
* Started new psychotherapy or had a change in the intensity of psychotherapy within 8 weeks before Screening.
* Is suicidal at Screening or Baseline
* History or current evidence within previous 3 months before Screening of uncontrolled, clinically significant neurological, gastrointestinal, respiratory, renal, hepatic, immunological, hematological, or other medical disorder, including cancer, that would jeopardize the safe participation of the subject in the study (in the opinion of the Investigator).
* History of thyroid disease
* History of multiple endocrine neoplasia syndrome
* Diagnosis of epilepsy or history of convulsions, including childhood febrile seizure. Use of co-administered drugs that may lower seizure threshold is excluded.
* Females who are pregnant, intend to become pregnant or are breastfeeding.
* Antidepressants: Prior use of psychedelics, ketamine, or esketamine, for the treatment of Major Depressive Disorder.
* Antidepressants: Current use, or use within 4 weeks prior to Screening, of any other augmentation agents for Major Depressive Disorder (e.g. second-generation antipsychotics \[SGA\], monoamine oxidase inhibitors \[MAOI\], tricyclic antidepressants \[TCA\], lithium, or bupropion)
* Current or prior use of treatment for hypothyroidism including but not limited to synthetic or natural thyroid hormone, triiodothyronine and/or thyroxine.
* Concomitant use of biotin of any dose and in any preparation 14 days prior to Day 1 until after the last study visit at Week 8 (Day 56).
* Medications that are strong cytochrome P450 3A4 inhibitors or strong cytochrome P450 3A4 inducers are not allowed.
* Prescription drug/controlled substance abuse, or illicit substance use within 1 year of Screening or positive urine drug results at Screening or Baseline for an illicit substance.
* History or presence of cataract on ophthalmic examination (including slit-lamp), glaucoma, inflammatory eye disease or prior ophthalmic surgical procedures or laser surgery in either eye

Where this trial is running

Birmingham, Alabama and 49 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Major Depressive Disorder
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.