ACP-211 Monotherapy for Major Depressive Disorder With Inadequate Antidepressant Response

NCT07284667 | Recruiting Phase 2 DMC FDA Drug

• 1 other identifier: ACP-211-002
• Study Type: interventional
• Target: 153
• Locations: 1 country
• Sites: 13

Brief Summary

The goal of this clinical trial is to learn if ACP-211 can help treat adults with major depressive disorder (MDD) who have not improved with antidepressant therapy (ADT), including those with treatment resistant depression (TRD). The main questions the study aims to answer are:

• Does ACP-211 work better than a placebo (a look-alike capsule with no medicine) to reduce symptoms of depression?
• What adverse events do participants have when taking ACP-211?

Conditions

Major Depressive Disorder (MDD); Depressive Disorder, Treatment-Resistant

Keywords

Major Depressive Disorder (MDD); Depressive Disorder, Treatment-Resistant; Antidepressive Agents; Randomized Controlled Trial; Double-Blind Method; Clinical Trial, Phase II; Psychiatric Status Rating Scales; Ketamine

Outcome Measures

Primary Outcomes (1)

• Change from Baseline in the Montgomery-Åsberg Depression Rating Scale (MADRS) total score at Day 28

  The MADRS is a clinician-rated tool that assesses the severity of depressive symptoms. It consists of 10 items, each scored from 0 (no symptoms) to 6 (severe symptoms), resulting in a total score range of 0 to 60. Higher scores indicate greater depression severity.

  Baseline and Day 28

Secondary Outcomes (1)

• Change from Baseline in the MADRS total score postdose at 24 hours (Day 2)

  Baseline and Day 2

Study Arms (3)

ACP-211 600 mg

EXPERIMENTAL

ACP-211 600 mg, administered orally twice weekly

Drug: ACP-211

ACP-211 300 mg

EXPERIMENTAL

ACP-211 300 mg, administered orally twice weekly

Drug: ACP-211

Placebo

PLACEBO COMPARATOR

Matching placebo, administered orally twice weekly

Drug: Placebo

Interventions

Placebo DRUG

Placebo control

Placebo

ACP-211 DRUG

ACP-211 monotherapy

ACP-211 300 mg; ACP-211 600 mg

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults ≥18 and ≤65 years of age
• Provides written informed consent
• Clinical diagnosis of MDD
• History of inadequate response to at least two antidepressants, with at least one inadequate response documented during the current episode
• Currently treated with an approved antidepressant at a stable dose prior to Screening
• MADRS total score ≥28, CGI-S score ≥4 , and QIDS-SR16 score ≥16 at Screening and Baseline
• Females of childbearing potential must have a negative pregnancy test and agree to use acceptable contraception; males must agree to use barrier protection and refrain from sperm donation

You may not qualify if:

• Current diagnosis of certain personality disorders or persistent depressive disorder
• Recent substance use disorders, excluding caffeine or nicotine
• Active suicidal risk or recent suicidal attempt
• History of schizophrenia, psychotic disorders, bipolar disorder, or MDD with psychotic features
• Current treatment requirement for PTSD, acute stress disorder, panic disorder, or OCD
• History of neuroleptic malignant syndrome, serotonin syndrome, or epilepsy (except single febrile seizure in infancy)
• Documented non-response to ADT, including ketamine or esketamine
• Allergy or sensitivity to ketamine or esketamine
• Significant cardiovascular disease
• Positive history of hepatitis B, hepatitis C, or HIV infection
• Unstable diabetes or uncontrolled medical conditions
• Positive urine drug test for an illicit drug or cannabis
• Received neuromodulation therapies (ECT,TMS, VNS, DBS) in the current depressive episode

Sponsors & Collaborators

• ACADIA Pharmaceuticals Inc.: lead

Study Sites (13)

University of Alabama at Birmingham

Birmingham, Alabama, 35294, United States

RECRUITING

Inland Psychiatric Medical Group

Chino, California, 91710, United States

RECRUITING

Mountain View Clinical Research

Denver, Colorado, 80209, United States

RECRUITING

Sandhill Research, LLC/DBA Accel Research Sites

Largo, Florida, 33777, United States

RECRUITING

Clinical Neuroscience Solutions, Inc.

Orlando, Florida, 32801, United States

RECRUITING

IPTB Clinical Research

Tampa, Florida, 33629, United States

RECRUITING

Vitalix Clinical, Inc.

Worcester, Massachusetts, 01608, United States

RECRUITING

Redbird Research LLC

Las Vegas, Nevada, 89134, United States

RECRUITING

CenExel Hassman Research Institute, LLC

Marlton, New Jersey, 08053, United States

RECRUITING

Integrative Clinical Trials LLC

Brooklyn, New York, 11229, United States

RECRUITING

Neuro-Behavioral Clinical Research

North Canton, Ohio, 44720, United States

RECRUITING

Dynamed Clinical Research LP d/b/a DM Clinical Research

Houston, Texas, 77081, United States

RECRUITING

Olympus Clinical Research, LLC

Katy, Texas, 77450, United States

RECRUITING

MeSH Terms

Conditions

Depressive Disorder, Major; Depressive Disorder, Treatment-Resistant

Condition Hierarchy (Ancestors)

Depressive Disorder; Mood Disorders; Mental Disorders

Central Study Contacts

Kerrin Young

CONTACT

kerrin.young@acadia-pharm.com; kerrin.young@acadia-pharm.com

Lori Lykens

CONTACT

kerrin.young@acadia-pharm.com; lori.lykens@acadia-pharm.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 9, 2025
• First Posted: December 16, 2025
• Study Start: November 14, 2025
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): September 1, 2027
• Last Updated: April 17, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

US (13)