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SPT-300 (GlyphAllo) for adults with major depressive disorder, with or without anxious distress

A Randomized, Parallel-Group, Double-Blind, Placebo-Controlled, Monotherapy Study of the Efficacy, Safety, and Tolerability of SPT-300 in Adults With Major Depressive Disorder (MDD), With or Without Anxious Distress

Phase 2 Interventional Seaport Therapeutics · NCT07065240

This will test whether a single medication, SPT-300 (GlyphAllo), is effective and safe for adults 18–65 who have major depressive disorder, with or without anxious distress.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment360 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorSeaport Therapeutics Industry-sponsored
Locations45 sites (Chino, California and 44 other locations)
Trial IDNCT07065240 on ClinicalTrials.gov

What this trial studies

This is a Phase 2, randomized, parallel-group, double-blind, placebo-controlled monotherapy trial comparing SPT-300 (GlyphAllo) to placebo in adults with major depressive disorder. Eligible participants are 18–65 years old with a current depressive episode lasting between 4 weeks and 18 months, and may include those with certain comorbid anxiety disorders if MDD is the primary diagnosis. Participants receive only the study drug or placebo while investigators monitor symptoms, safety, and tolerability over the treatment period. The trial is sponsored by Seaport Therapeutics with operational support from Premier Research and is conducted at Seaport Investigator sites in Southern California.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18–65 with a primary diagnosis of major depressive disorder, a current depressive episode of 4 weeks to 18 months, and who can consent and comply with study procedures and contraception requirements if applicable.

Not a fit: People outside the 18–65 age range, those who are pregnant or breastfeeding, those whose depressive episode is shorter than 4 weeks or longer than 18 months, or whose MDD is not the primary diagnosis are unlikely to be eligible or to benefit from participation.

Why it matters

Potential benefit: If successful, SPT-300 could offer a new monotherapy option that reduces depressive symptoms and is well tolerated in adults with MDD, including some people with anxious distress.

How similar studies have performed: Randomized, placebo-controlled Phase 2 trials of novel antidepressants have produced mixed results, and SPT-300 appears to be a novel compound with limited publicly available efficacy data to date.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Participant is a male or female between 18 and 65 years of age, inclusive willing and able and have capacity to provide written informed consent.
* Participants must have a primary diagnosis of MDD. Participants with a diagnosis of comorbid generalized anxiety disorder, social anxiety disorder, or panic disorder (with or without agoraphobia) may be included if not the focus of treatment over the past 6 months prior to Screening and the Investigator considers MDD to be the primary diagnosis at Screening and Baseline.
* Eligible participants must have a current depressive episode of at least 4 weeks, but no greater than 18 months in duration prior to Screening.
* Women of childbearing potential (WOCP) must not plan to become pregnant during the course of the study or be currently breastfeeding. WOCP agree to use an acceptable form of highly effective contraception during participation in the study and for 30 days after receiving the last dose of study treatment.
* Body mass index (BMI) between 18 to 40 kg/m2, inclusive.
* Participant is willing and able to refrain from the use of drugs of abuse.

Exclusion Criteria:

* History of, or current presentation consistent with:

  1. any depressive episode with psychotic or catatonic features.
  2. any bipolar manic, hypomanic or mixed episode, and substance-induced (e.g., antidepressant-induced) manic, hypomanic/mixed episode.
  3. bipolar disorder, including history of bipolar depression, or current presentation consistent with bipolar depression.
  4. schizophrenia, schizoaffective, or other psychotic disorder.
  5. obsessive-compulsive disorder.
  6. any persistent neurocognitive disorder.
* History of treatment-resistant depression defined as 2 or more failed treatments of adequate dose and duration in the current depressive episode.
* Psychiatric hospitalization within current depressive episode.
* Evidence or history of clinically significant diseases which can affect the patients' participation.
* Previous history of intolerance or significant adverse effects, including drug allergy to allopregnanolone or any components of the SPT-300/placebo formulation.
* Participant has a history of drug or alcohol use disorder.
* Participants with a positive test for cannabinoids.
* Clinically significant risk of suicide or harm to self or others.

Where this trial is running

Chino, California and 44 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Major Depressive DisorderMajor Depressive Disorder With Anxious DistressDepressive DisorderDepressionAnxietyMood DisordersBUOY-1 StudySPT-300
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.