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)

August 14, 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

Status

Indicates the current recruitment status or the expanded access status.
Enrolling by invitation

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
360

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

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
    • Brandenburg
      • Berlin, Brandenburg, Germany, D-10629
        • Seaport Investigator Site
    • Mecklenburg-Vorpommern
      • Schwerin, Mecklenburg-Vorpommern, Germany, 19053
        • Seaport Investigator Site
  • Hungary
      • Budapest, Hungary, 1033
        • Seaport Investigator Site
      • Budapest, Hungary, 1134
        • 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
      • San Jose, California, United States, 95124
        • Seaport Investigator Site
    • Connecticut
      • Cromwell, Connecticut, United States, 06416
        • Seaport Investigator Site
    • Florida
      • Lauderhill, Florida, United States, 33319
        • Seaport Investigator Site
      • Palm Bay, Florida, United States, 32905
        • Seaport Investigator Site
      • 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
      • Cedarhurst, New York, United States, 11516
        • Seaport Investigator Site
      • New York, New York, United States, 10029
        • Seaport Investigator Site
      • Staten Island, New York, United States, 10314
        • Seaport Investigator Site
    • Ohio
      • Independence, Ohio, United States, 44131
        • Seaport Investigator Site
      • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Seaport Therapeutics

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Premier Research

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 2, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 2, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 2, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 9, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 14, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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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