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Efficacy and Safety of AGN-151607-DP in Adults with Major Depressive Disorder: A Randomized, Placebo‑Controlled Phase 2 Study

Investigational
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What is this trial about?

A plain-language summary of the goals, design and what participants do

Major Depressive Disorder is a condition in which a person feels a low mood most of the day, loses interest in activities, and may have trouble sleeping, eating, or concentrating. The study evaluates an injection called AGN-151607-DP (also known as gemibotulinumtoxinA), which contains a form of botulinum toxin protein. A matching injection that does not contain the active drug is also used for comparison.

The purpose of the study is to find out whether the active injection can reduce depressive symptoms more effectively than the comparison injection. Participants are randomly assigned to receive either the active injection or the comparison injection, and neither the participants nor the study staff know which one is given (a double‑blind design). The study follows a parallel‑group format, meaning each group receives only its assigned treatment throughout the initial phase.

After a single injection, participants return for several visits over a few weeks to answer questions about mood and to complete brief questionnaires that measure changes in depression. One of the questionnaires used is the Montgomery–Åsberg Depression Rating Scale, a set of questions that helps track how severe the symptoms are. Another tool, the Clinical Global Impression of Severity–Major Depressive Disorder, asks clinicians to rate overall severity. Safety is checked at each visit by asking about any new health problems. After the blinded period, participants may be offered an open‑label phase where the active injection is given to all.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline Assessment

    After joining the study you will attend a baseline visit where the study team will confirm eligibility and record your health information.

    You will complete questionnaires that measure your depression severity, such as the Montgomery–Åsberg Depression Rating Scale and the Clinical Global Impression of Severity.

  2. Step 2

    Randomization

    You will be assigned by chance to one of two groups; this process is called randomized.

    The assignment is kept secret from you and the study staff (double‑blind) so that expectations do not influence the results.

  3. Step 3

    Study Injection

    You will receive a single injection under the skin. The injection will contain either AGN‑151607‑DP (also known as gemibotulinumtoxinA) or an inactive substance called placebo.

    The amount of active drug is 00 units, delivered in a solution for injection.

    The injection is given only once during the blinded phase.

  4. Step 4

    Follow‑up Visits During Blinded Phase

    You will return to the clinic for several scheduled visits (for example, every few weeks) to allow the study team to evaluate changes in your depression scores and to monitor safety.

    At each visit you will repeat the depression questionnaires and answer questions about any side effects.

  5. Step 5

    Transition to Open‑Label Treatment

    After the blinded phase is completed, the study enters an open‑label period. During this time, all participants receive the active medication, AGN‑151607‑DP, regardless of previous group assignment.

    Neither you nor the staff will be blinded during this period because everyone knows the injection contains the active drug.

  6. Step 6

    Open‑Label Follow‑up

    You will continue to attend regular visits while receiving the active medication to assess longer‑term effects and safety.

    The same depression questionnaires will be completed at each visit.

  7. Step 7

    Final Assessment and Study End

    At the end of the study you will have a final visit where the study team records your overall depression score, any remaining side effects, and other health information.

    After this visit your participation in the trial is complete.

Who can join the trial?

5 criteria

  • Be between 18 and 70 years old when you sign the consent form.
  • Be either male or female.
  • Have had at least one previous episode that meets the criteria of DSM‑5‑TR for major depressive disorder (the standard guideline doctors use to diagnose depression).
  • Have a Body Mass Index (BMI) between 18 and 45, which is a simple calculation using your height and weight.
  • Currently be in a major depressive episode that scores at least 22 on the HAM‑D17 questionnaire (a tool that measures how severe depression symptoms are), scores at least 4 on the CGI‑S‑MDD rating (a doctor’s overall impression of how severe the depression is), and has lasted at least 4 weeks but no longer than 24 months.

Who cannot join the trial?

8 criteria

  • If you have not improved by at least half after trying two or more appropriate antidepressant medicines for your current depression episode (this is called treatment resistance).
  • If you are currently taking any antidepressant medication or using herbal or homeopathic products meant for depression within the past two weeks (or longer if the medicine stays in your body for a longer time).
  • If you have ever been diagnosed with a schizophrenia spectrum or other psychotic disorder, which means you have experienced a loss of contact with reality such as hearing or seeing things that aren’t there or having false beliefs.
  • If you have ever been diagnosed with bipolar disorder, a condition that involves extreme mood swings between very high (manic) and very low (depressive) states.
  • If you have ever been diagnosed with major neurocognitive disorder, a serious decline in memory and thinking abilities (often called dementia).
  • If you have ever been diagnosed with a neurodevelopmental disorder that is more than mild and makes it hard for you to understand the study, give consent, follow directions, or stay safe (for example, moderate autism or severe ADHD).
  • If you have ever been diagnosed with a dissociative disorder, a condition where a person experiences disruptions in memory, identity, or perception of reality.
  • If you have ever been diagnosed with post‑traumatic stress disorder (PTSD), a condition that can develop after a very stressful or scary event and includes symptoms like flashbacks, avoidance, and heightened anxiety.
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Investigated drugs

gemibotulinumtoxinA (AGN-151607-DP)
This is a specially prepared form of botulinum toxin type A that contains the active toxin protein linked to other natural proteins from the bacteria. It is given as a liquid that is injected under the skin. In the study, participants receive this injection as the only treatment they are taking, and the researchers are looking to see if it can improve symptoms of major depressive disorder compared with a placebo. The goal is to find out whether this injection can safely reduce depression symptoms when used by itself.

What is already known about the treatment

gemibotulinumtoxinA - It is administered as an injection of a sterile solution that is placed under the skin. The drug is still investigational and is currently being studied in Phase 2 clinical trials for depression. It is aimed at treating major depressive disorder by blocking the release of certain neurotransmitters from nerve endings, which helps calm over‑active brain pathways that affect mood. It belongs to the class of botulinum toxin type A neurotoxins.

Investigated diseases

Major Depressive Disorder - Major Depressive Disorder is a mood condition characterized by persistent low mood, loss of interest, and changes in sleep and appetite. People experience feelings of sadness, hopelessness, and difficulty concentrating that last for at least two weeks. The condition often develops gradually, with symptoms worsening over time if not addressed. It can affect daily activities, relationships, and work performance. Episodes may recur, and the severity can vary from mild to severe.
Trial detailsLast updated 13 Nov 2026
Age18+ yearsPhasePhase IITrial ID2025-525047-40-00Protocol codeM26-083Estimated enrolment376 patientsSponsorAbbVie Deutschland GmbH & Co. KG

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