ABX-002 · program

Elunetirom (ABX-002) for Bipolar depression

Phase 2ActiveAutobahn Therapeutics, Inc.
  • Fast Track

Indications for ABX-002: Bipolar depression · Phase 2 Major depressive disorder · Phase 2

Adjunctive bipolar I/II depression. Open-label Phase 2 AMPLIFY-BD (NCT06869187, ABX-002-2002) evaluating 6 weeks of once-daily oral ABX-002 added to existing therapy, with brain energy-metabolism neuroimaging (31P-MRS) and depression rating scales. Initiation announced 8 Jan 2025 (CT.gov actual start 28 Mar 2025). Positive topline reported 4 Jun 2026: mean HAMD-17 reduction of 16.8 points at Week 6 (p<0.001), 75% response and 50% remission. FDA granted Fast Track designation for adjunctive bipolar depression on 26 May 2026. Program remains active (active, not recruiting) with full data anticipated 2H 2026.

Data current as of

Development timeline

Phase 2Oct 2024 – Jun 2026
  1. metAMPLIFY-BD met its primary endpoint: HAMD-17 -16.8 at Week 6 (p<0.001), 75% response, 50% remission in adjunctive bipolar depression.↗
  2. Autobahn announced initiation of the open-label Phase 2 bipolar depression trial (AMPLIFY-BD); ClinicalTrials.gov records an actual start date of 28 Mar 2025.↗
  3. FDA cleared the IND for ABX-002 as an adjunctive treatment for bipolar depression; company planned to begin the Phase 2 trial by year-end 2024.↗

Readouts

  • 2026-06-04ReportedTopline datametNCT06869187

    AMPLIFY-BD met its primary endpoint: HAMD-17 -16.8 at Week 6 (p<0.001), 75% response, 50% remission in adjunctive bipolar depression. ↗

Clinical trials in Bipolar depression

NCT06869187ABX-002-2002Phase 2Activen=35

A Phase 2 Open-label Study of the Effect of Adjunctively Administered ABX-002 in Adults With Bipolar Disorder Experiencing an Episode of Depression (AMPLIFY-BD)

Started Mar 2025· Primary completion Apr 2026· 📍 14 sites across 1 country (United States)

metsecondaryHAMD-17 change from baseline at Week 2 — mean reduction 9.7 points (<0.001)

Early, rapid antidepressant effect at Week 2 (-9.7 points, p<0.001) per company topline.

metsecondaryHAMD-17 change from baseline at Week 4 — mean reduction 13.7 points (<0.001)

Continued separation at Week 4 (-13.7 points, p<0.001) per company topline.

metsecondaryCorrelation of change in anterior cingulate cortex NTP/Pi and PCr/Pi (31P-MRS) with percent change in HAMD-17 at Week 6

Pre-specified key secondary 31P-MRS brain energy-metabolism endpoints plus significant changes in functional brain connectivity were reported as supportive of target engagement; quantitative correlation values not disclosed in topline.

metprimaryHAMD-17 total score change from baseline to Week 6 — mean reduction 16.8 points (<0.001)

Open-label adjunctive ABX-002 produced a mean 16.8-point HAMD-17 reduction at Week 6 (p<0.001) in 21 adults with bipolar I/II depression in the topline analysis; 75% response (>=50% HAMD-17 reduction) and 50% remission (HAMD-17 <=7).

Formulations

FormulationRouteRegimenPharmacokinetics
Elunetirom oral solutionOral solution in 1-mL cyclic olefin polymer prefilled syringes, taken on an empty stomach in the morning followed by 240 mL (8 oz) of water
Oral, once-daily brain-penetrant small-molecule prodrug (prodrug of LL-340001); dosed once daily for six weeks in the Phase 2 adjunctive bipolar-depression trial
OralOnce daily—

Mechanism of action (compound-wide)

Elunetirom (ABX-002) is a blood-brain-barrier-penetrant amide prodrug that is cleaved by fatty acid amide hydrolase (FAAH) to the active metabolite ABX-002A (LL-340001), a potent, selective, centrally acting agonist of thyroid hormone receptor beta (TRbeta / THRB). Selective CNS TRbeta agonism is hypothesized to relieve depression by enhancing neuronal mitochondrial/energy metabolism (reflected in 31P-MRS brain phosphate measures) and neuroplasticity, while the prodrug design and TRbeta selectivity limit the peripheral cardiac/metabolic effects of systemic thyroid hormone. No clean published TRbeta binding constant (Ki/EC50) is catalogued for elunetirom or ABX-002A in IUPHAR/GtoPdb, so affinity is left null.

TargetActionAffinity
TRbetaprimaryTHRBAgonist—ⓘ

← Full ABX-002 compound page (identity, identifiers, all indications)

Sources

  1. AMPLIFY-BD: Phase 2 open-label study of adjunctive ABX-002 in bipolar depression (NCT06869187) — ClinicalTrials.gov
  2. Autobahn announces FDA clearance of IND for ABX-002 as adjunctive treatment for bipolar depression (22 Oct 2024) — Autobahn Therapeutics
  3. Autobahn reports positive Phase 2 topline data for elunetirom in bipolar depression (4 Jun 2026) — Autobahn Therapeutics
  4. Autobahn Therapeutics Announces Initiation of Phase 2 Trial of ABX-002 as an Adjunctive Treatment for Bipolar Depression — Autobahn Therapeutics
  5. Elunetirom (ABX-002, ligand 12973) - brain-penetrant TRbeta agonist amide prodrug (FAAH-cleaved to ABX-002A) — IUPHAR/BPS Guide to Pharmacology
  6. Study of ABX-002 for the Adjunctive Treatment of Bipolar Depression (AMPLIFY-BD), NCT06869187 — ClinicalTrials.gov