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SPT-300

Phase 2

Major Depressive Disorder (MDD) | Small molecule | Psychiatry |Seaport Therapeutics, Inc.|Last Updated: May 19, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials2
Total Enrollment720
FDA Designations
No designations recorded
Clinical Trials (2)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT07161700An 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)PHASE2 ENROLLING BY_INVITATION 360Sep 2, 2025May 1, 2027May 19, 202631 United States, Bulgaria +4
NCT07065240A Study to Evaluate the Efficacy and Safety of SPT-300 (GlyphAllo) in Participants With Major Depressive Disorder, With or Without Anxious Distress (BUOY-1 Study)PHASE2 RECRUITING 360Jun 19, 2025Mar 1, 2027May 19, 202659 United States, Bulgaria +5
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Study Endpoints
Primary Endpoints
Safety and tolerability assessments based on Treatment-emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs) and validated clinical scales and procedures
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.

Change From Baseline to Day 42 in Hamilton Depression Rating Scale-17 (HAM-D-17) Total Score
Baseline (Day 0) to Day 42

HAM-D-17 is a 17-item, clinician-administered rating scale to assess the severity of symptoms in participants diagnosed with depression. The HAM-D-17 comprises individual ratings related to the following symptoms: depressed mood (sadness, hopeless, helpless, worthless), feelings of guilt, suicide, insomnia (early, middle, late), work and activities, retardation (slowness of thought and speech; impaired ability to concentrate; decreased motor activity), agitation, anxiety (psychic and somatic), somatic symptoms (gastrointestinal and general), genital symptoms, hypochondriasis, loss of weight, and insight. HAM-D Total Scores range from 0 to 52, with higher scores indicating more severe depression.

Secondary Endpoints
Change From Baseline to Day 42 in Clinical Global Impression - Severity (CGI-S)
Baseline (Day 0) to Day 42
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Study Design & Arms
AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
SPT-300EXPERIMENTALParticipants will receive SPT-300 capsules once daily for 42 days
PlaceboPLACEBO_COMPARATORParticipants will receive matching placebo once daily for 42 days
Interventions
NameTypeDescription
SPT-300DRUGA prodrug of allopregnanolone, a small molecule drug
PlaceboDRUGPlacebo for SPT-300
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Eligibility Criteria
Age Range18 Years — 66 Years
SexALL
Healthy VolunteersNo
Study Sites31

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 currentl...

Countries:United StatesBulgariaCzechiaGermanyPolandSlovakiaHungary
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT07065240primaryCompletionDate: changed
LOWMay 26, 2026NCT07161700primaryCompletionDate: changed
LOWMay 24, 2026NCT07065240studyFirstPostDate: changed
LOWMay 24, 2026NCT07161700studyFirstPostDate: changed