Efficacy and Safety of MK-1942 When Added to Stable Antidepressant Therapy in Participants With Treatment-Resistant Depression (TRD) (MK-1942-006)

April 13, 2026 updated by: Merck Sharp & Dohme LLC

A Phase 2a, Randomized, Placebo-Controlled Clinical Study to Evaluate the Efficacy and Safety of MK-1942 Added to Stable Antidepressant Therapy in Participants With Treatment-Resistant Depression

The main purpose of this study is to assess the efficacy and safety of daily and intermittent dosing of MK-1942 compared to placebo among participants with Treatment-Resistant Depression (TRD) on a stable course of antidepressant therapy. The dual primary hypotheses of the study are that the daily MK-1942 treatment or intermittent MK-1942 treatment are superior to placebo in reducing Montgomery-Asberg Depression Rating Scale (MADRS) score.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Terminated

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 (Actual)

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.
99

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

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35233
        • University of Alabama at Birmingham - School of Medicine-Psychiatry ( Site 1073)
    • Arkansas
      • Little Rock, Arkansas, United States, 72211
        • Preferred Research Partners ( Site 1079)
      • Little Rock, Arkansas, United States, 72211
        • Woodland International Research Group ( Site 1017)
    • California
      • Bellflower, California, United States, 90706
        • CITrials-Outpatient Facility ( Site 1098)
      • Colton, California, United States, 92324
        • Axiom Research ( Site 1053)
      • Garden Grove, California, United States, 92845
        • Collaborative Neuroscience Network, LLC. ( Site 1032)
      • Santa Ana, California, United States, 92705
        • CITrials ( Site 1105)
    • Connecticut
      • Hartford, Connecticut, United States, 06106
        • Institute of Living ( Site 1061)
    • Florida
      • Fort Myers, Florida, United States, 33912
        • Gulfcoast Clinical Research Center ( Site 1110)
      • Hallandale, Florida, United States, 33009
        • Velocity Clinical Research, Hallandale Beach ( Site 1116)
      • Jacksonville, Florida, United States, 32256
        • Clinical Neuroscience Solutions, Inc. dba CNS Healthcare ( Site 1039)
      • Lauderhill, Florida, United States, 33319
        • Innovative Clinical Research ( Site 1044)
      • Miami, Florida, United States, 33016
        • Behavioral Clinical Research ( Site 1037)
      • Naples, Florida, United States, 34105
        • Aqualane Clinical Research ( Site 1113)
      • Orlando, Florida, United States, 32803
        • APG RESEARCH, LLC ( Site 1087)
      • Tampa, Florida, United States, 33613
        • University of South Florida-Psychiatry and Behavioral Neurosciences ( Site 1093)
      • Winter Park, Florida, United States, 32792
        • K2 Medical Research - Winter Park ( Site 1115)
    • Georgia
      • Atlanta, Georgia, United States, 30331
        • Atlanta Center for Medical Research ( Site 1022)
      • Decatur, Georgia, United States, 30030
        • iResearch Atlanta ( Site 1040)
      • Marietta, Georgia, United States, 30060
        • Psych Atlanta ( Site 1108)
      • Savannah, Georgia, United States, 31405
        • iResearch Savannah ( Site 1041)
    • Illinois
      • Chicago, Illinois, United States, 60622
        • Ascension Saint Elizabeth ( Site 1003)
    • Maryland
      • Gaithersburg, Maryland, United States, 20877
        • CBH Health ( Site 1076)
    • Massachusetts
      • Boston, Massachusetts, United States, 02131
        • Boston Clinical Trials ( Site 1028)
    • Michigan
      • Ann Arbor, Michigan, United States, 48026
        • University of Michigan-Psychiatry ( Site 1051)
    • Nevada
      • Las Vegas, Nevada, United States, 89102
        • Altea Research ( Site 1018)
    • New Jersey
      • Berlin, New Jersey, United States, 08009
        • Hassman Research Institute ( Site 1036)
      • Princeton, New Jersey, United States, 08540
        • Global Medical Institutes LLC; Princeton Medical Institute ( Site 1049)
    • New Mexico
      • Albuquerque, New Mexico, United States, 87109
        • Albuquerque Neuroscience Inc. ( Site 1107)
    • New York
      • New York, New York, United States, 10022
        • Hapworth Research Inc.-Clinical Research Department ( Site 1090)
      • New York, New York, United States, 10036
        • Manhattan Behavioral Medicine ( Site 1096)
      • Staten Island, New York, United States, 10314
        • Richmond Behavioral Associates ( Site 1011)
    • North Carolina
      • Charlotte, North Carolina, United States, 28211
        • New Hope Clinical Research ( Site 1082)
      • Hickory, North Carolina, United States, 28601
        • Clinical Trials of America, LLC ( Site 1103)
    • Ohio
      • North Canton, Ohio, United States, 44720
        • Neuro-Behavioral Clinical Research ( Site 1045)
    • Oklahoma
      • Oklahoma City, Oklahoma, United States, 73118
        • Paradigm Research Professionals ( Site 1089)
    • Pennsylvania
      • Media, Pennsylvania, United States, 19063
        • Suburban Research Associates-Clinical Research ( Site 1042)
      • Philadelphia, Pennsylvania, United States, 19104
        • Penn Medicine: University of Pennsylvania Health System-Mood Disorders Treatment and Research Proga
      • Plymouth Meeting, Pennsylvania, United States, 19462
        • Keystone Clinical Studies ( Site 1031)
    • Texas
      • Houston, Texas, United States, 77030
        • Baylor College of Medicine ( Site 1019)
      • Plano, Texas, United States, 75093
        • AIM Trials, LLC ( Site 1111)
    • Utah
      • Draper, Utah, United States, 84020
        • Cedar Clinical Research ( Site 1023)
    • Vermont
      • Woodstock, Vermont, United States, 05091
        • Woodstock Research Center ( Site 1084)
    • Washington
      • Bellevue, Washington, United States, 98007
        • Northwest Clinical Research Center ( Site 1112)
      • Everett, Washington, United States, 98201
        • Core Clinical Research ( Site 1081)

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

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Meets the diagnostic criteria for moderate-to-severe major depressive disorder (MDD) without psychotic features according to Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria at Visit 1 (Screening)
  • Is currently experiencing an episode of moderate-to-severe MDD
  • Had an inadequate response to 1 to 4 different courses of antidepressant therapy for the current episode of moderate-to-severe MDD
  • Has been on a stable course of antidepressant therapy for ≥4 weeks before Visit 1 (Screening)
  • Has not initiated psychotherapy for depressive symptoms in the last 3 months before Visit 1 (Screening) and agrees not to initiate a new psychotherapy for depressive symptoms or to modify their current regimen of psychotherapy for depressive symptoms from Visit 1 (Screening) to Visit 9 (Post-dose Follow-up Visit)
  • Male participants are eligible if they agree to the following during the intervention period and for at least 7 days after last dose of study intervention: Be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long term and persistent basis) and agree to remain abstinent or agrees to use contraception unless confirmed to be azoospermic (vasectomized or secondary to medical cause)
  • A female participant is eligible to participate if she is not a woman of childbearing potential (WOCBP) or a WOCBP who is not pregnant, breastfeeding, or within 3 months from postpartum. WOCBP should use contraceptive methods that are highly effective as per the study specifications or be abstinent from heterosexual intercourse as their preferred and usual lifestyle, have a negative pregnancy test at screening, immediately prior to the first dosing event, and at regular intervals during the study period, and abstain from breastfeeding during the study intervention period and for at least 7 days after last study intervention
  • Has a reliable contact person

Exclusion Criteria:

  • Has an ongoing episode of MDD that started more than 2 years before Visit 1 (Screening)
  • Has a current or prior history of one or more of the following: a) diagnosis of a psychotic disorder b) chronic convulsive disorder, except febrile seizures during childhood c) neurodegenerative disorder, traumatic brain injury causing ongoing cognitive difficulties, or any chronic organic disease of the central nervous system d) intellectual disability of a severity that would affect the ability of the participant to participate in the study e) bipolar and related disorders, MDD with psychosis f) MDD with mixed features g) posttraumatic stress disorder if not in remission for at least 5 years before Visit 1 (Screening) h) obsessive-compulsive disorder i) autism spectrum disorder
  • Meets criteria for substance abuse or dependence disorder currently or within the 12 months before Visit 1 (Screening)
  • Has a known allergy or intolerance to the active or inert ingredients in MK-1942
  • Has a history of malignancy ≤3 years before Visit 1 (Screening) except for adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer
  • Has a Body Mass Index (BMI) >40 kg/m2
  • Has HIV or nonstable hypothyroidism, diabetes, cardiovascular disease, or respiratory disease
  • Failed to adequately respond to treatment with ketamine or esketamine for the current or a prior episode of MDD
  • Previously received electroconvulsive therapy within the past 10 years, deep brain stimulation, or vagal nerve stimulation for treatment of depression
  • Is imminent risk for self harm or harm to others
  • Is currently participating in or has previously participated in an interventional clinical study within the 2 months before Visit 1 (Screening), or has participated in >4 interventional clinical studies within the 2 years before Visit 1 (Screening)
  • Has known renal disease or is experiencing renal insufficiency
  • Routinely consumes >3 alcoholic drinks per day. One standard drink is defined as any beverage containing 14 gram (g) of pure alcohol
  • Requires use of a language interpreter to participate in the study
  • Had major surgery or donated or lost >1 unit of blood within the 4 weeks before Visit 1 (Screening)
  • Is pregnant or is currently breastfeeding or plans to breastfeed during the course of the study
  • Is a woman with <12 months of amenorrhea and is receiving hormone replacement therapy (HRT) or an estrogen-based contraceptive
  • Is or has an immediate family member who is investigational site or Sponsor staff directly involved with this study

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

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: MK-1942 Daily Dose Group
Participants receive a total daily dose titrated from 5 mg to 20 mg of MK-1942 twice daily (BID), orally, over 4 weeks of treatment duration: 5 mg in Week 1, 10 mg in Week 2, and 20 mg in Weeks 3 and 4. Participants receive MK-1942 and matching placebo packaged in blister cards with an equal number of capsules administered in the morning and evening regardless of treatment assignment.
Drug: MK-1942
MK-1942 (5 mg or 10 mg capsules) titrated from 5 mg to 20 mg dose BID or 10 mg BIW over 4 weeks.
Drug: Placebo
Dose matched placebo capsules BID orally over 4 weeks.
Experimental: MK-1942 Intermittent Dose Group
Participants receive a total daily dose of 10 mg of MK-1942 twice weekly (BIW), orally, for Weeks 1-4. Participants receive MK-1942 and matching placebo packaged in blister cards with an equal number of capsules administered in the morning and evening regardless of treatment assignment.
Drug: MK-1942
MK-1942 (5 mg or 10 mg capsules) titrated from 5 mg to 20 mg dose BID or 10 mg BIW over 4 weeks.
Drug: Placebo
Dose matched placebo capsules BID orally over 4 weeks.
Placebo Comparator: Placebo
Participants receive a dose-matched placebo BID, orally, for 4 weeks. Participants receive matching placebo packaged in blister cards with an equal number of capsules administered in the morning and evening regardless of treatment assignment.
Drug: Placebo
Dose matched placebo capsules BID orally over 4 weeks.

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
Number of Participants Who Experienced An Adverse Event (AE)
Time Frame: Up to approximately 6 Weeks
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.
Up to approximately 6 Weeks
Number of Participants Who Discontinued Study Treatment Due to an AE
Time Frame: Up to approximately 4 Weeks
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.
Up to approximately 4 Weeks
Change From Baseline in Montgomery-Asberg Depression Rating Scale (MADRS) Total Score to Week 3
Time Frame: Baseline and Week 3
The change from baseline in Montgomery-Asberg Depression Rating Scale (MADRS) score is presented. MADRS includes 10 participant-rated items, each scored on a scale from 0 (normal, no symptom) to 6 (symptoms of maximum severity) [total scores range from 0 (normal/no symptom) to 60 (severe depression). Higher scores correspond to greater symptom severity, whereas a negative change from baseline score indicates improvement.
Baseline and Week 3
Change From Baseline in MADRS Total Score to Week 1
Time Frame: Baseline and Week 1
The change from baseline in Montgomery-Asberg Depression Rating Scale (MADRS) score is presented. MADRS includes 10 participant-rated items, each scored on a scale from 0 (normal, no symptom) to 6 (symptoms of maximum severity) [total scores range from 0 (normal/no symptom) to 60 (severe depression). Higher scores correspond to greater symptom severity, whereas a negative change from baseline score indicates improvement.
Baseline and Week 1

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in the Hamilton Depression Rating Scale (HAM-D17) Total Score to Week 3
Time Frame: Baseline and Week 3
The HAM-D17 scale was used to evaluate the depressive symptoms experienced over the past week. The HAM-D17 is a 17-item participant-rated scale, with each item scored from 0 to 2 or 4 (depending on the question) reflective of severity (0 is absence of symptom and higher scores indicate greater symptom severity). The total score ranges from 0 (no apparent symptoms) to 52 (most severe symptoms). A negative change from baseline indicates symptom improvement, and vice versa.
Baseline and Week 3
Change From Baseline in the HAM-D17 Scale Total Score to Week 1
Time Frame: Baseline and Week 1
The HAM-D17 scale was used to evaluate the depressive symptoms experienced over the past week. The HAM-D17 is a 17-item participant-rated scale, with each item scored from 0 to 2 or 4 (depending on the question) reflective of severity (0 is absence of symptom and higher scores indicate greater symptom severity). The total score ranges from 0 (no apparent symptoms) to 52 (most severe symptoms). A negative change from baseline indicates symptom improvement, and vice versa.
Baseline and Week 1
Change From Baseline in the Clinician Global Impression-Severity (CGI-S) Total Score to Week 3
Time Frame: Baseline and Week 3
The CGI-S is rated on a 7-point scale using a range of responses from 1 (normal, not at all ill) to 7 (among the most extremely ill patients). Higher score corresponds to greater symptom severity. A negative change score indicates improvement, and vice versa.
Baseline and Week 3
Change From Baseline in the Clinician Global Impression-Severity (CGI-S) Total Score to Week 1
Time Frame: Baseline and Week 1
The CGI-S is rated on a 7-point scale using a range of responses from 1 (normal, not at all ill) to 7 (among the most extremely ill patients). Higher score corresponds to greater symptom severity. A negative change score indicates improvement, and vice versa.
Baseline and Week 1
Mean Plasma Concentration of MK-1942 Plasma Concentration
Time Frame: Day 15: 12 (Daily Dose) or 72 (Intermittent Dose) hours postdose
The mean plasma concentration of MK-1942 10 mg given as a single or multiple dose regimen was determined.
Day 15: 12 (Daily Dose) or 72 (Intermittent Dose) hours postdose

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.
Merck Sharp & Dohme LLC

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.
  • Study Director: Medical Director, Merck Sharp & Dohme LLC

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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.
May 20, 2021

Primary Completion (Actual)

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.
September 8, 2023

Study Completion (Actual)

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.
September 8, 2023

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).
December 4, 2020

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.
December 4, 2020

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.
December 11, 2020

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.
May 4, 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.
April 13, 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.
April 1, 2026

More Information

Terms related to this study

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.
  • 1942-006
  • MK-1942-006 (Other Identifier: MSD)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

http://engagezone.msd.com/doc/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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