GH Research Announces Publication of Phase 2b Results for Mebufotenin (GH001) in JAMA Psychiatry and Reports New Finding of Severity-Independent Efficacy in TRD

• Phase 2b results for GH001 in TRD now published and peer-reviewed in JAMA Psychiatry
• New peer-reviewed article in forthcoming issue of Psychopharmacology Bulletin demonstrates that GH001 efficacy is independent of prior antidepressant treatment failures

DUBLIN, March 25, 2026 (GLOBE NEWSWIRE) -- GH Research PLC (Nasdaq: GHRS), a clinical-stage biopharmaceutical company dedicated to transforming the lives of patients by developing a practice-changing treatment in depression, today announced two peer-reviewed publications from its Phase 2b clinical program of GH001 in treatment-resistant depression (TRD): the primary trial results in JAMA Psychiatry, and a new analysis demonstrating that efficacy is independent of the number of prior lifetime treatment failures in a forthcoming issue of Psychopharmacology Bulletin.

JAMA Psychiatry Publication

The peer-reviewed article, titled “GH001 vs Placebo in Patients with Treatment-Resistant Depression” has been published today in JAMA Psychiatry (DOI: 10.1001/jamapsychiatry.2026.0096). The publication includes the complete results from the randomized, double-blind, placebo-controlled Phase 2b trial of mebufotenin in patients with TRD, including all primary and secondary efficacy endpoints, safety and tolerability data, and initial results from the 6-month open-label extension. These results were previously reported in topline form.

“Publication in JAMA Psychiatry provides independent peer-reviewed validation of our Phase 2b findings,” said Dr. Velichka Valcheva, Chief Executive Officer. “This supports our ongoing efforts to advance GH001 into global pivotal trials.”

New Finding: GH001 Efficacy Is Independent of Prior Treatment Failures

A supporting peer-reviewed article, titled “GH001 Efficacy is Independent of Prior Antidepressant Treatment Failures in Treatment-Resistant Depression: A Post Hoc Analysis of a Phase 2b Randomized Controlled Trial,” will be published in a forthcoming issue of Psychopharmacology Bulletin.

In TRD, a well-established finding across multiple treatment modalities is that remission rates decline significantly with each successive antidepressant treatment failure. This pattern, first quantified in the landmark STAR*D trial (see About STAR*D below), represents a fundamental challenge in treating patients with extensive treatment histories. The new analysis of Phase 2b data demonstrates that GH001 does not follow this pattern:

• Day 8 remission rates ranged from 53.9% to 63.6% across patients with 2 to ≥5 prior lifetime antidepressant failures, with no decline at higher failure counts;
• End of trial/Month 6 remission rates ranged from 61.5% to 85.7% across the same subgroups; and
• No meaningful correlation was observed between the number of prior lifetime treatment failures and Montgomery-Åsberg Depression Rating Scale (MADRS) improvement at Day 8 (r=−0.13; P=0.44) or among those who completed the 6-month OLE (r=−0.10; P=0.60).

“One interesting, unanticipated finding from this trial is that the benefit of GH001 appeared to be independent of the number of prior lifetime antidepressant failures. Remission rates were consistently high across subgroups – in contrast to the decline seen with each successive treatment that we observed in the STAR*D trial. This suggests patients who have not responded to three or more prior courses of antidepressant therapy might benefit from this novel therapy,” said Michael E. Thase, MD, Professor of Psychiatry, Perelman School of Medicine at the University of Pennsylvania.

Consistent with the findings of this article, GH001 efficacy is also independent from prior treatment failures within the current depressive episode in this Phase 2b trial.

About GH Research PLC

GH Research PLC is a clinical-stage biopharmaceutical company dedicated to transforming the lives of patients by developing a practice-changing treatment in depression. GH Research PLC’s initial focus is on developing its novel and proprietary mebufotenin therapies for the treatment of patients with TRD. Based on the observed clinical activity in our Phase 2b trial, where the primary endpoint was met with a MADRS reduction from baseline of −15.5 points compared with placebo on Day 8 (P