An Open-Label Extension Study to Evaluate the Safety and Tolerability of SPT-300 (GlyphAllo) in Participants With Major Depressive Disorder, With or Without Anxious Distress (BUOY-1 OLE Study)

May 15, 2026 updated by: Seaport Therapeutics

A 6-Week, Multicenter, Open-Label, Monotherapy, Extension Study of SPT-300 in Adults With Major Depressive Disorder, With or Without Anxious Distress

This is an open-label, monotherapy, extension study to evaluate the safety and tolerability of SPT-300 (GlyphAllo) in adults with major depressive disorder (MDD), with or without anxious distress.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

360

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Bulgaria
      • Plovdiv, Bulgaria, 4004
        • Seaport Investigator Site
      • Sofia, Bulgaria, 1000
        • Seaport Investigator Site
  • Czechia
      • Brno, Czechia, 602 00
        • Seaport Investigator Site
      • Prague, Czechia, 100 00
        • Seaport Investigator Site
      • Prague, Czechia, 186 00
        • Seaport Investigator Site
      • Prague, Czechia, 110 00
        • Seaport Investigator Site
      • Prague, Czechia, 160 00
        • Seaport Investigator Site
  • Germany
      • Chemnitz, Germany, 09111
        • Seaport Investigator Site
    • Mecklenburg-Vorpommern
      • Schwerin, Mecklenburg-Vorpommern, Germany, 19053
        • Seaport Investigator Site
  • Poland
      • Bialystok, Poland, 15-404
        • Seaport Investigator Site
      • Bialystok, Poland, 15-464
        • Seaport Investigator Site
      • Bydgoszcz, Poland, 85-080
        • Seaport Investigator Site
      • Gdansk, Poland, 80-438
        • Seaport Investigator Site
      • Leszno, Poland, 64-100
        • Seaport Investigator Site
      • Poznan, Poland, 60-744
        • Seaport Investigator Site
      • Tuszyn, Poland, 95-080
        • Seaport Investigator Site
  • Slovakia
      • Rimavská Sobota, Slovakia, 979 01
        • Seaport Investigator Site
      • Vranov nad Topľou, Slovakia, 09301
        • Seaport Investigator Site
  • United States
    • California
      • Chino, California, United States, 91710
        • Seaport Investigator Site
      • Garden Grove, California, United States, 92845-2506
        • Seaport Investigator Site
      • Glendale, California, United States, 91206
        • Seaport Investigator Site
    • Florida
      • West Palm Beach, Florida, United States, 33407
        • Seaport Investigator Site
    • Georgia
      • Atlanta, Georgia, United States, 30328
        • Seaport Investigator Site
      • Decatur, Georgia, United States, 30030
        • Seaport Investigator Site
    • Massachusetts
      • Boston, Massachusetts, United States, 02116
        • Seaport Investigator Site
    • Missouri
      • St Louis, Missouri, United States, 63141
        • Seaport Investigator Site
    • New York
      • Brooklyn, New York, United States, 11235
        • Seaport Investigator Site
      • New York, New York, United States, 10029
        • Seaport Investigator Site
      • Staten Island, New York, United States, 10314
        • Seaport Investigator Site
    • Ohio
      • North Canton, Ohio, United States, 44720
        • Seaport Investigator Site
    • Texas
      • Irving, Texas, United States, 75062
        • Seaport Investigator Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participant who completed treatment in Study SPT-300-2024-203 (i.e., participant who competed Visit 8 [Day 42] of Study SPT-300-2024-203 [BUOY-1 Study]).
  • Women of childbearing potential (WOCP) must not plan to become pregnant during the course of the study or be currently breastfeeding. WOCP must agree to use a highly effective form of contraception during participation in the study and for 30 days after receiving the last dose of study treatment.
  • Participant is willing and able to refrain from the use of drugs of abuse.

Exclusion Criteria:

  • Participants who, in the opinion of the Investigator, medical monitor, or Sponsor, should not participate in the study.
  • Participants who, in the judgment of the Investigator, were noncompliant with trial procedures or with study treatment administration during the double-blind study (BUOY-1 Study).
  • Female participants with a positive urine pregnancy test result. Female participants may be enrolled without a negative urine test if they are surgically sterile or at least 2 years post-menopause.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: SPT-300
Participants will receive SPT-300 capsules once daily for 42 days
Drug: SPT-300
A prodrug of allopregnanolone, a small molecule drug
Other Names:
  • LYT-300
  • GlyphAllo
  • Glyph Allopregnanolone

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety and tolerability assessments based on Treatment-emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs) and validated clinical scales and procedures
Time Frame: Up to Day 49
Adverse events (AEs) are monitored from Day 1 to 49. A TEAE is as any AE with an onset after first dose of study treatment up to Day 49. Clinically significant abnormalities in clinical laboratory evaluations, ECGs, vital signs, physical examinations and Columbia Suicide Severity Rating Scale (C-SSRS) will be reported as TEAEs.
Up to Day 49

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Seaport Therapeutics

Collaborators

Premier Research

Investigators

  • Principal Investigator: David Walling, Ph.D., Collaborative Neuroscience Research - Garden Grove

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 2, 2025

Primary Completion (Estimated)

May 1, 2027

Study Completion (Estimated)

May 1, 2027

Study Registration Dates

First Submitted

September 2, 2025

First Submitted That Met QC Criteria

September 2, 2025

First Posted (Actual)

September 9, 2025

Study Record Updates

Last Update Posted (Actual)

May 19, 2026

Last Update Submitted That Met QC Criteria

May 15, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • SPT-300-2024-204
  • 2025-522347-18-00 (Ctis)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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