A Study to Evaluate the Safety and Efficacy of CD388 for Prevention of Influenza
ANCHOR
A Phase 3 Randomized, Double-Blind, Placebo-Controlled, Multicenter Study to Evaluate the Safety and Efficacy of CD388, a Novel Long-Acting Antiviral Conjugate, for the Prevention of Influenza in Adults and Adolescents at Higher Risk of Developing Influenza Complications
1 other identifier
interventional
7,500
4 countries
157
Brief Summary
The purpose of this study is to evaluate how well CD388 works in preventing symptomatic laboratory-confirmed influenza infections, as compared to placebo, when given as a single dose via 3 subcutaneous (SQ) injections to adult and adolescent participants who are at higher risk of developing influenza complications, and to evaluate the safety and tolerability of CD388, as compared to placebo.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for phase_3
Started Sep 2025
Shorter than P25 for phase_3
157 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
August 29, 2025
CompletedFirst Posted
Study publicly available on registry
September 8, 2025
CompletedStudy Start
First participant enrolled
September 25, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
January 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
January 1, 2027
May 19, 2026
May 1, 2026
1.3 years
August 29, 2025
May 18, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Percentage of Participants Experiencing Protocol-defined Influenza-like Illness (ILI) Occurring ≥7 Days after and up to 24 Weeks after Administration of Study Drug
Percentage of participants experiencing protocol-defined ILI occurring after administration of CD388, with influenza infection confirmed by a reverse-transcriptase polymerase chain reaction positive (RT-PCR+) result based on a nasopharyngeal (NP) swab assayed at a central laboratory (first occurrence only), as compared to placebo.
From Day 8 up to 24 weeks after study drug dosing
Secondary Outcomes (5)
Incidence and Severity of Treatment-Emergent Adverse Events (TEAEs) after Administration of Study Drug
From Day 1 through Day 197/End of Study (EOS) after study drug dosing
Trough Plasma Concentration at 24 Weeks (C[trough24w]) Following Administration of CD388
Based on sampling done at onsite visits on Day 8 (±3 days), Day 29 (±3 days), and Day 197/EOS (±7 days)
Maximum Plasma Concentration (C[max]) Following Administration of CD388
At onsite visits done on Day 8 (±3 days), Day 29 (±3 days), and Day 197/EOS (±7 days)
Area Under the Plasma Concentration-Time Curve (AUC) Following Administration of CD388
At onsite visits done on Day 8 (±3 days), Day 29 (±3 days), and Day 197/EOS (±7 days)
Detection of Anti-Drug Antibodies (ADAs) in Participants Administered CD388
On Day 1 (pre-dose baseline) and at onsite visits done on Day 29 (±3 days) and Day 197/EOS (±7 days)
Study Arms (2)
CD388
EXPERIMENTALParticipants are randomized to receive 450 milligrams (mg) CD388 by SQ injection. Participants are randomized at a 1:1 ratio between the 2 arms.
Placebo
PLACEBO COMPARATORParticipants are randomized to receive placebo by SQ injection. Participants are randomized at a 1:1 ratio between the 2 arms.
Interventions
Eligibility Criteria
You may qualify if:
- Must be 12 years of age or older at the time of signing the informed consent.
- Written informed consent and any locally required authorization (e.g., Health Insurance Portability and Accountability Act \[HIPAA\] in the US) obtained from the participant before performing any protocol-related procedures, including screening evaluations. For participants under the legal age of consent as defined by local regulations, the parent(s) or legal guardian(s) may be required to give their signed written informed consent and participants may sign an assent form as specified by local law.
- Has negative rapid antigen tests for influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) prior to dosing at Day 1.
- Weight is ≥ 40 kilograms (kg) at screening.
- Body Mass Index (BMI; calculated as weight in kg divided by height in meters \[m\] squared)) is ≥ 18 kg/m\^2 at screening.
- In the opinion of the Investigator, must be able to comply with the requirements of the protocol and be able to read, understand, and complete questionnaires in the electronic diary (eDiary), work with smartphones/tablets/computers (if applicable, with assistance by a caregiver, surrogate, or legally authorized representative), and be willing and able to adhere to the prohibitions and restrictions specified in this protocol. If an appropriate language version is not available for the eDiary assessments, the participant should not be enrolled.
- Must be assessed by the Investigator as medically stable and not requiring significant change in maintenance therapy and has not been hospitalized for worsening disease or any significant medical event during the 2 months before screening
- Must agree to the following contraception requirements:
- a. Females of childbearing potential must use a highly effective, preferably user-independent, method of contraception (failure rate of less than 1 percent per year when used consistently and correctly) from ≥2 weeks prior to randomization and agree to remain on a highly effective method from Day 1 until 32 weeks after study intervention administration, the end of relevant systemic exposure. Note: A woman is considered of childbearing potential (i.e., fertile) following menarche and until becoming postmenopausal, unless permanently sterile. Permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy. A postmenopausal state is defined as no menses for 12 months without an alternative medical cause. A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to confirm a postmenopausal state in women not using hormonal contraception or hormonal replacement therapy. However, in the absence of 12 months of amenorrhea, a single FSH measurement is insufficient.
- Note: Contraceptive (birth control) use by participants should be consistent with local regulations regarding the acceptable methods of contraception for those participating in clinical studies.
- Must agree not to donate blood or blood products from Day 1 until 32 weeks after study intervention administration.
- Must be willing to provide verifiable identification, has means to be contacted, and is able to contact the Investigator/study site and communicate reliably during participation in the study.
- Has a history of pulmonary disease; specifically:
- Chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema, graded as follows using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) Categories A, B, and E (ABE) (i.e., GOLD ABE) assessment tool:
- Gold Grade 2 (moderate) or Grade 3 (severe) with following exacerbation history, within 1 year of screening
- +26 more criteria
You may not qualify if:
- A female who is pregnant or lactating.
- Known or suspected allergy or history of anaphylaxis or other serious adverse reactions to zanamivir (following administration of inhaled or intravenous formulations), monoclonal antibodies (including crystallizable fragment \[Fc\] domains), or any of the components of CD388 or placebo.
- Has been diagnosed with influenza (i.e., with medical history \[including verbal\] of influenza) within 6 months prior to randomization.
- Has received the current seasonal inactivated influenza vaccine or live attenuated influenza vaccine within the 14 days prior to dosing on Day 1. (NOTE: Participant may have received recombinant influenza vaccine up to the day of dosing on Day 1.)
- Has an acute (time-limited) or febrile (temperature ≥38.0 degrees Celsius \[ºC\] \[≥100.4 degrees Fahrenheit {ºF}\]) illness within 7 days prior to planned dosing on Day 1.
- Has had close contact (including household contact) with someone with laboratory-confirmed influenza or SARS-CoV-2 or with someone who has been treated with antiviral therapies for influenza or SARS-CoV-2 within the 7 days prior to randomization.
- Has a clinically unstable condition including, but not limited to, a psychiatric condition, including recent (within the past year) or active suicidal ideation/behavior, or any other condition for which, in the opinion of the Investigator, may lead to hospitalization or death within the study period and that suggests that study enrollment would not be in the participant's best interest and/or that could prevent, confound, or limit the protocol-specified assessments.
- Has any history of alcohol or drug abuse that, in the opinion of the Investigator, would adversely impact the conduct of the study.
- Had major surgery (e.g., major cardiac, pulmonary or abdominal operation) within 4 weeks prior to randomization, or will not have fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study.
- Has severe CKD (equivalent to an eGFR less than 30 mL/min/1.73 m\^2 as calculated by CKD-EPI equation for adults or the CKiD U25 equation for adolescents), or is receiving hemodialysis.
- Current or planned participation in another clinical study in which study intervention is being administered during participation in the current study. NOTE: Concurrent enrollment is allowed during the follow-up phase of the other clinical study or in case the study intervention in the other clinical study is a marketed product already approved for another indication - exception being if the other study requires study interventions that could affect the safety assessments of the present study (e.g., clinical laboratory tests).
- Receipt within the past 30 days or 5 half-lives (whichever is longer) or anticipated receipt of any drug or other biologic agent (e.g., monoclonal antibodies) administered for the prevention or treatment of influenza.
- Receipt of any formulation of immunoglobulin within 14 days prior to planned study intervention administration.
- Receipt of any experimental drug, vaccine, or biologic agent within the 90 days or 5 half-lives (whichever is longer) prior to study intervention administration.
- Has a clinically significant bleeding disorder (e.g., factor deficiency, coagulopathy, or platelet disorder) or medical history of significant bleeding or bruising following intramuscular or SQ injections or venipuncture. NOTE: Participants receiving apixaban or warfarin may be enrolled if the Investigator determines risk of SQ treatment with study intervention on Day 1 is minimal.
- +3 more criteria
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (157)
Pinnacle Research Group, LLC
Anniston, Alabama, 36207, United States
Cullman Clinical Trials
Cullman, Alabama, 35055, United States
HOPE Research Institute
Glendale, Arizona, 85308, United States
Desert Clinical Research, LLC / Avacare
Mesa, Arizona, 85213, United States
Foothills Research Center / Avacare
Phoenix, Arizona, 85044, United States
Fiel Family and Sports Medicine / Avacare
Tempe, Arizona, 85283, United States
HOPE Research Institute
Tempe, Arizona, 85284, United States
Arizona Clinical Trials
Tucson, Arizona, 85711, United States
Del Sol Research Management, LLC
Tucson, Arizona, 85715, United States
Triallogix Medical Corporation
Fullerton, California, 92835, United States
National Institute of Clinical Research, Inc.
Garden Grove, California, 92844, United States
Eximia Research-CA, LLC
La Mesa, California, 91942, United States
Kinetic Clinical Research, LLC dba Long Beach Clinical Trials
Long Beach, California, 90806, United States
Seaside Medical Group
Oceanside, California, 92058, United States
Profound Research, LLC
Pasadena, California, 91105, United States
Paradigm Clinical Research
Redding, California, 96001, United States
Artemis Institute for Clinical Research
San Diego, California, 92103, United States
Acclaim Clinical Research
San Diego, California, 92120, United States
Diablo Clinical Research, Inc.
Walnut Creek, California, 94598, United States
Tekton Research, LLC
Denver, Colorado, 80238, United States
Tekton Research, LLC
Fort Collins, Colorado, 80525, United States
Critical Care, Pulmonary and Sleep Associates PLLP / Avacare
Lakewood, Colorado, 80228, United States
Tekton Research, LLC
Longmont, Colorado, 80501, United States
New England Research Associates
Bridgeport, Connecticut, 06606, United States
Stamford Therapeutics Consortium
Stamford, Connecticut, 06905, United States
Emerson Clinical Research Institute
Washington D.C., District of Columbia, 20009, United States
Imagine Research - Palm Beach County
Boynton Beach, Florida, 33435, United States
Innovative Research of West Florida, Inc.
Clearwater, Florida, 33756, United States
Hillcrest Medical Research, LLC
DeLand, Florida, 32720, United States
Health Awareness, Inc.
Jupiter, Florida, 33458, United States
Columbus Clinical Services, LLC
Miami, Florida, 33125, United States
Flourish Research - Miami, LLC DBA Flourish Research
Miami, Florida, 33135, United States
South Florida Research Center, Inc.
Miami, Florida, 33135, United States
Floridian Clinical Research, LLC
Miami Lakes, Florida, 33016, United States
Healthcare Clinical Data, Inc.
North Miami, Florida, 33161, United States
Clinical Neuroscience Solutions, Inc.
Orlando, Florida, 32806, United States
Progressive Medical Research
Port Orange, Florida, 32127, United States
Health Awareness, Inc.
Port Saint Lucie, Florida, 34952, United States
Global Clinical Professionals
St. Petersburg, Florida, 33705, United States
Clinical Site Partners, LLC dba Flourish Research
Winter Park, Florida, 32789, United States
Agile Clinical Research Trials, LLC
Atlanta, Georgia, 30328, United States
DelRicht Research
Atlanta, Georgia, 30329, United States
Clinical Research Atlanta
Stockbridge, Georgia, 30281, United States
Paradigm Clinical Research
Boise, Idaho, 83709, United States
Velocity Clinical Research - Boise
Meridian, Idaho, 83642, United States
Great Lakes Clinical Trials, LLC dba Flourish Research
Chicago, Illinois, 60640, United States
Velocity Clinical Research - Valparaiso
Valparaiso, Indiana, 46383, United States
Integrated Clinical Trial Services, LLC
West Des Moines, Iowa, 50265, United States
Johnson County Clin-Trials, LLC
Lenexa, Kansas, 66219, United States
AMR Clinical
Newton, Kansas, 67114, United States
DelRicht Research
Louisville, Kentucky, 40205, United States
Elevate Clinical Research
Lake Charles, Louisiana, 70605, United States
DelRicht Research
New Orleans, Louisiana, 70115, United States
DelRicht Research
Prairieville, Louisiana, 70769, United States
Annapolis Internal Medicine / Avacare
Annapolis, Maryland, 21401, United States
Jadestone Clinical Research, LLC
Silver Spring, Maryland, 20904, United States
Skylight Health Research
Burlington, Massachusetts, 01803, United States
Profound Research, LLC
Clarkston, Michigan, 48346, United States
Profound Research, LLC
Dearborn, Michigan, 48126, United States
Profound Research, LLC
Farmington Hills, Michigan, 48334, United States
Javara, Inc.
Mankato, Minnesota, 56001, United States
DelRicht Research
Gulfport, Mississippi, 39503, United States
Clay Platte Family Medicine, PC / Avacare
Kansas City, Missouri, 64151, United States
DelRicht Research
Springfield, Missouri, 65807, United States
Sundance Clinical Research, LLC
St Louis, Missouri, 63141, United States
Montana Medical Research, Inc.
Missoula, Montana, 59808, United States
Methodist Physicians Clinic / Avacare
Fremont, Nebraska, 68025, United States
Velocity Clinical Research - Omaha
Omaha, Nebraska, 68134, United States
Midwest Regional Health Services, LLC / Avacare
Omaha, Nebraska, 68144, United States
Henderson Clinical Trials
Henderson, Nevada, 89052, United States
Excel Clinical Research
Las Vegas, Nevada, 89109, United States
Santa Rosa Medical Centers of Nevada / Avacare
Las Vegas, Nevada, 89119, United States
Las Vegas Clinical Trials, LLC
North Las Vegas, Nevada, 89030, United States
IMA Clinical Research
Warren Township, New Jersey, 07059, United States
Brooklyn Clinical Research
Brooklyn, New York, 11226, United States
Finger Lakes Medical Research, PLLC dba Certified Research Associates
Cortland, New York, 13045, United States
Drug Trials America
Hartsdale, New York, 10530, United States
Rochester Clinical Research
Rochester, New York, 14609, United States
CHEAR Center, LLC
The Bronx, New York, 10455, United States
DelRicht Research
Charlotte, North Carolina, 28205, United States
Eximia EquiHealth Research, LLC
Durham, North Carolina, 27704, United States
Monroe Biomedical Research
Monroe, North Carolina, 28112, United States
West Clinical Research, Inc.
Morehead City, North Carolina, 28557, United States
OnSite Clinical Solutions, LLC
Salisbury, North Carolina, 28144, United States
Wilmington Health
Wilmington, North Carolina, 28412, United States
Wake Forest University Health Sciences
Winston-Salem, North Carolina, 27157, United States
Velocity Clinical Research - Cleveland
Beachwood, Ohio, 44122, United States
Velocity Clinical Research - Springdale
Cincinnati, Ohio, 45246, United States
Centricity Research Columbus Ohio Multispecialty
Columbus, Ohio, 43213, United States
PriMed Clinical Research
Dayton, Ohio, 45429, United States
Tekton Research, LLC
Edmond, Oklahoma, 73013, United States
Lynn Health Science Institute East
Oklahoma City, Oklahoma, 73111, United States
DelRicht Research
Tulsa, Oklahoma, 74133, United States
Tekton Research, LLC
Yukon, Oklahoma, 73099, United States
Altoona Center for Clinical Research
Duncansville, Pennsylvania, 16635, United States
Central Erie Primary Care
Erie, Pennsylvania, 16508, United States
Hatboro Medical Associates / Avacare
Horsham, Pennsylvania, 19044, United States
DM Clinical Research
Philadelphia, Pennsylvania, 19107, United States
DelRicht Research
Charleston, South Carolina, 29407, United States
Tribe Clinical Research, LLC
Greenville, South Carolina, 29607, United States
Spartanburg Medical Research
Spartanburg, South Carolina, 29303, United States
Velocity Clinical Research - Spartanburg
Spartanburg, South Carolina, 29303, United States
DelRicht Research
Hendersonville, Tennessee, 37075, United States
DCT-HCWC, LLC dba Discovery Clinical Trials
Dallas, Texas, 75230, United States
Zenos Clinical Research
Dallas, Texas, 75230, United States
Lonestar Clinical Research, LLC
Dallas, Texas, 75243, United States
Laguna Clinical Research Associates, LLC
Laredo, Texas, 78041, United States
Epic Clinical Research
Lewisville, Texas, 75057, United States
Elevate Clinical Research
McAllen, Texas, 78504, United States
Pearland Physicians
Pearland, Texas, 77581, United States
Research Your Health
Plano, Texas, 75093, United States
Clinical Trials of Texas, LLC dba Flourish Research
San Antonio, Texas, 78229, United States
Elevate Clinical Research
Seabrook, Texas, 77586, United States
Javara, Inc.
Stephenville, Texas, 76401, United States
DM Clinical Research
Tomball, Texas, 77375, United States
Cope Family Medicine / Avacare
Bountiful, Utah, 84010, United States
Olympus Family Medicine / Avacare
Salt Lake City, Utah, 84117, United States
Charlottesville Medical Research Center, LLC
Charlottesville, Virginia, 22911, United States
Clinical Research Partners, LLC
Richmond, Virginia, 23226, United States
Rainier Clinical Research Center
Renton, Washington, 98057, United States
Equipo Ciencia
Buenos Aires, C1428BNF, Argentina
Emeritus Research Sydney
Botany, New South Wales, 2019, Australia
Australian Clinical Research Network Pty Ltd
Maroubra, New South Wales, 2035, Australia
AIM Research
Merewether, New South Wales, 2291, Australia
Momentum Clinical Research St Leonards
Saint Leonards, New South Wales, 2065, Australia
Momentum Clinical Research Taringa
Taringa, Queensland, 4062, Australia
Emeritus Research Camberwell
Camberwell, Victoria, 3124, Australia
Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust
Birmingham, England, B15 2TH, United Kingdom
Fylde Coast Clinical Research at Layton Medical Centre
Blackpool, England, FY3 7EN, United Kingdom
Southmead Hospital, North Bristol NHS Trust - Clinical Research Centre
Bristol, England, BS10 5NB, United Kingdom
Velocity Clinical Research - Bristol
Bristol, England, BS8 2RA, United Kingdom
Eynsham Medical Centre
Eynsham, England, OX29 4QB, United Kingdom
Velocity Clinical Research - High Wycombe
High Wycombe, England, HP11 2QW, United Kingdom
HMC Health, The Meadows Centre for Health, The Great West Surgery
Hounslow, England, TW4 7NR, United Kingdom
Leeds Teaching Hospitals NHS Trust - St. James's University Hospital
Leeds, England, LS9 7TF, United Kingdom
University Hospitals of Leicester NHS Trust - Leicester Royal Infirmary
Leicester, England, LE1 5WW, United Kingdom
hVIVO Services Limited
London, England, E1 1EQ, United Kingdom
Panthera Enfield
London, England, EN3 4GS, United Kingdom
Velocity Clinical Research - North London
London, England, N12 8BU, United Kingdom
North Manchester General Hospital
Manchester, England, M8 5RB, United Kingdom
The University of Nottingham Health Service
Nottingham, England, NG7 2QW, United Kingdom
Wansford Research LTD
Peterborough, England, PE8 6PL, United Kingdom
University Hospitals Plymouth NHS Trust
Plymouth, England, PL6 8DH, United Kingdom
Panthera Preston
Preston, England, PR2 9QB, United Kingdom
Panthera Rochdale
Rochdale, England, OL11 4AU, United Kingdom
Velocity Clinical Research - Romford
Romford, England, RM1 3PJ, United Kingdom
Warrington and Halton Teaching Hospitals NHS Foundation Trust
Runcorn, England, WA7 2DA, United Kingdom
Salford Royal Hospital
Salford, England, M6 8HD, United Kingdom
Panthera Sheffield
Sheffield, England, S2 5FX, United Kingdom
University Hospital Southampton NHS Foundation Trust, NIHR Southampton Clinical Research Facility
Southampton, England, SO16 6YD, United Kingdom
Royal Cornwall Hospitals NHS Trust
Truro, England, TR1 3LJ, United Kingdom
Windrush Medical Practice
Witney, England, OX28 6JS, United Kingdom
Panthera York
York, England, YO24 4LJ, United Kingdom
Aberdeen Royal Infirmary
Aberdeen, Scotland, AB25 2ZD, United Kingdom
NHS Lothian - Western General Hospital
Edinburgh, Scotland, EH4 2XU, United Kingdom
Queen Elizabeth University Hospital, Glasgow Clinical Research Facility
Glasgow, Scotland, G51 4TF, United Kingdom
Cardiff and Vale UHB - University Hospital of Wales
Cardiff, Wales, CF14 4XW, United Kingdom
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- STUDY DIRECTOR
Barbara Haber, MD
Merck Sharp & Dohme LLC
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 3
- Allocation
- RANDOMIZED
- Masking
- QUADRUPLE
- Who Masked
- PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
- Purpose
- PREVENTION
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
August 29, 2025
First Posted
September 8, 2025
Study Start
September 25, 2025
Primary Completion (Estimated)
January 1, 2027
Study Completion (Estimated)
January 1, 2027
Last Updated
May 19, 2026
Record last verified: 2026-05
Data Sharing
- IPD Sharing
- Will not share