Recruiting

Phase 3

CD388A Study to Evaluate the Safety and Efficacy of MK-1406/CD388 for Prevention of Influenza (MK-1406-005/CD388.SQ.3.06)

Sponsor:

Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA)

Code:

NCT07159763

Conditions

Influenza

Eligibility Criteria

Sex: All

Age: 12+

Healthy Volunteers: Not accepted

Interventions

MK-1406

Placebo

Study Details

Brief summary:

Approximately one billion cases of seasonal influenza occur annually. Of these, 3 to 5 million illnesses are severe and responsible for up to 650,000 deaths per year (WHO 2025). Yearly administration of an influenza vaccine for the prevention of influenza is currently recommended. However, the real-world vaccine effectiveness varied from 10% to 60% in the general population across the years of 2004 to 2024, with effectiveness in most years below 50% (CDC 2025) and decreasing to as low as 5% in immunocompromised individuals (Hughes 2021).

The goal of this study is to learn whether MK-1406 (CD388) can help prevent the flu in people who are at higher risk of becoming seriously ill from influenza. Researchers want to find out if MK-1406 dosed at a single study visit can provide protection against influenza compared with placebo. The study will include adolescents and adults who may be more vulnerable to complications from influenza because of their age, health conditions, or weakened immune systems. Researchers will also evaluate the safety of MK-1406 and how well participants tolerate the study medicine.

Conditions

Influenza

Study ID

NCT07159763

Start date

Sep 25, 2025

Status verified date

Oct, 2026

Completion date

Jun 30, 2027

Anticipated

Primary completion date

Jun 30, 2027

Anticipated

Eligibility Criteria

Sex: All

Age: 12+

Healthy Volunteers: Not accepted

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

Primary Stratum A (non-immunocompromised participants who have chronic stable medical conditions) and Primary Stratum B (participants who are immunocompromised either due to underlying disease or receipt of immunosuppressive medications)

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 kg

Primary Stratum A only

Has a history of pulmonary disease
Has moderate to severe asthma, as defined by the Global Initiative for Asthma (GINA 2025)
Has existing cardiac disease
Has insulin-dependent diabetes
Has moderate renal impairment
Is ≥ 65 years of age at the time of randomization but does not meet any of the above criteria for Primary Stratum A, and is otherwise healthy

Primary Stratum B only

Has a solid tumor diagnosis AND has received chemotherapy and/or immunotherapy within 1 year of screening
Has a diagnosis of a hematologic malignancy within 5 years of screening AND has received any chemotherapy or biologic therapy within 1 year of screening
Participants who have had a solid organ transplant (SOT) must satisfy all of the following:

Has received a kidney, liver, heart, or lung transplant more than 6 months prior to screening
Is currently receiving at least two immunosuppressive medications
Participants who have had a hematopoietic stem cell transplant (HSCT) must satisfy at least one of the following:

Has a history of hematopoietic stem cell transplantation (HSCT) (i.e., autologous, allogeneic, bone marrow, peripheral blood stem cell, tandem \[peripheral blood and marrow\]) within 1 year of screening
Has a history of non-autologous HSCT with graft-versus-host disease (GvHD) requiring active treatment with immunosuppressants (e.g., systemic corticosteroids ≥1 mg/kg at screening), regardless of the duration of time since HSCT
Is receiving immunosuppressive medicines
Has received chimeric antigen receptor-modified T-cell therapy
Has received B-cell depleting therapies (e.g., rituximab, ocrelizumab, ofatumumab, alemtuzumab) within the 12 months prior to screening
Has a diagnosis of any primary immunodeficiency except immunoglobulin A (IgA) deficiency
Has advanced or untreated human immunodeficiency virus (HIV) infection

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

Known or suspected allergy or history of anaphylaxis or other serious adverse reactions to zanamivir (following administration of inhaled or intravenous formulations), monoclonal antibody (mAbs (including Fc domains)), or any of the components of CD388 or placebo
Has an acute (time-limited) or febrile (temperature ≥ 38.0°C \[≥ 100.4°F\]) illness within 7 days prior to planned dosing on Day 1
Has severe chronic kidney disease (CKD) or is receiving hemodialysis
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., mAbs) administered for the prevention or treatment of influenza
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 subcutaneous (SC) injections or venipuncture
Has previously enrolled in this study (CD388.SQ.3.06)

Study Design

Enrollment

10000 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: MK-1406

Participants will receive 450 milligrams (mg) dose of MK-1406 (CD388) by subcutaneous (SC) injection.

placebo comparator: Placebo

Participants will receive placebo by SC injection.

Interventions

MK-1406

MK-1406 liquid for injection administered subcutaneously (SC)

Placebo

MK-1406 matched liquid for SC injection

Primary outcome measure

Number of Participants Experiencing Protocol-defined Influenza-like Illness (ILI) Occurring ≥7 Days after and up to 24 Weeks after Administration of Study Drug [ Time Frame: Up to approximately 24 weeks post dose ]

Central Contacts and Locations

Central contacts

Toll Free Number

1-888-577-8839 Trialsites@msd.com

Locations

Pinnacle Research Group ( Site 0505)

Recruiting

Anniston, Alabama, United States, 36207

Contacts

Study Coordinator

256-452-1160

Cullman Clinical Trials ( Site 0538)

Recruiting

Cullman, Alabama, United States, 35055

Contacts

Study Coordinator

256-708-2826

Hope Research Institute ( Site 0575)

Recruiting

Glendale, Arizona, United States, 85308

Contacts

Study Coordinator

602-288-4673

Hope Research Institute ( Site 0587)

Recruiting

Tempe, Arizona, United States, 85284

Contacts

Study Coordinator

480-786-6655

Del Sol Research Management, LLC ( Site 0515)

Recruiting

Tucson, Arizona, United States, 85715

Contacts

Study Coordinator

520-647-9926

Triallogix Medical Corporation ( Site 0615)

Recruiting

Fullerton, California, United States, 92835

Contacts

Study Coordinator

281-772-4450

Profound Research LLC ( Site 0574)

Recruiting

Pasadena, California, United States, 91105

Contacts

Study Coordinator

62679312270

Paradigm Clinical Research Centers, Inc ( Site 0518)

Recruiting

Redding, California, United States, 96001

Contacts

Study Coordinator

530-232-3000

Tekton Research ( Site 0611)

Recruiting

Denver, Colorado, United States, 80238

Contacts

Study Coordinator

303-345-6994

Critical Care Pulmonary & Sleep Associates - CCT Research ( Site 0525)

Recruiting

Lakewood, Colorado, United States, 80228

Contacts

Study Coordinator

303-951-0600

New England Research Associates, LLC ( Site 0558)

Recruiting

Bridgeport, Connecticut, United States, 06606

Contacts

Study Coordinator

203-374-9816

Health Awareness, Inc. ( Site 0524)

Recruiting

Jupiter, Florida, United States, 33458

Contacts

Study Coordinator

561-741-2033

Floridian Clinical Research, LLC ( Site 0534)

Recruiting

Miami Lakes, Florida, United States, 33016

Contacts

Study Coordinator

305-330-9977

Progressive Medical Research ( Site 0579)

Recruiting

Port Orange, Florida, United States, 32127

Contacts

Study Coordinator

386-304-7070

Health Awareness, Inc. ( Site 0541)

Recruiting

Port Saint Lucie, Florida, United States, 34952

Contacts

Study Coordinator

561-741-2033

GCP- Global Clinical Research Professionals, LLC ( Site 0595)

Recruiting

St. Petersburg, Florida, United States, 33714

Contacts

Study Coordinator

208-346-8900

Clinical Site Partners, LLC dba Flourish Research ( Site 0540)

Recruiting

Winter Park, Florida, United States, 32789

Contacts

Study Coordinator

667-210-5368

Agile Clinical Research Trials, LLC ( Site 0600)

Recruiting

Atlanta, Georgia, United States, 30328

Contacts

Study Coordinator

404-400-2255

DelRicht Research ( Site 0583)

Recruiting

Atlanta, Georgia, United States, 30329

Contacts

Study Coordinator

504-336-2667

Clinical Research Atlanta ( Site 0531)

Recruiting

Stockbridge, Georgia, United States, 30281

Contacts

Study Coordinator

770-507-6867

Paradigm Clinical Research - Boise ( Site 0614)

Recruiting

Boise, Idaho, United States, 83709

Contacts

Study Coordinator

208-801-7438

Velocity Clinical Research, Boise ( Site 0535)

Recruiting

Meridian, Idaho, United States, 83642

Contacts

Study Coordinator

208-377-8653

Great Lakes Clinical Trials - Ravenswood ( Site 0564)

Recruiting

Chicago, Illinois, United States, 60640

Contacts

Study Coordinator

773-769-3500

DM Clinical Research ( Site 0502)

Recruiting

Palos Heights, Illinois, United States, 60463

Contacts

Study Coordinator

445-300-9011

Integrated Clinical Trial Services, Inc ( Site 0576)

Recruiting

West Des Moines, Iowa, United States, 50265

Contacts

Study Coordinator

515-223-2300

Johnson County Clin-Trials ( Site 0530)

Recruiting

Lenexa, Kansas, United States, 66219-1376

Contacts

Study Coordinator

913-825-4400

Alliance for Multispecialty Research, LLC ( Site 0561)

Recruiting

Newton, Kansas, United States, 67114

Contacts

Study Coordinator

316-283-0828

DelRicht Research ( Site 0594)

Recruiting

Prairieville, Louisiana, United States, 70769-4212

Contacts

Study Coordinator

225-412-0316

Annapolis Internal Medicine - CCT Research ( Site 0580)

Recruiting

Annapolis, Maryland, United States, 21401

Contacts

Study Coordinator

410-897-9841

Skylight Health Research, Inc ( Site 0609)

Recruiting

Burlington, Massachusetts, United States, 01803

Contacts

Study Coordinator

781-328-2491

Michigan Hematology & Oncology Consultants ( Site 0610)

Recruiting

Dearborn, Michigan, United States, 48126

Contacts

Study Coordinator

313-816-1600

Mankato Clinic ( Site 0573)

Recruiting

Mankato, Minnesota, United States, 56001

Contacts

Study Coordinator

507-216-0972

DelRicht Research ( Site 0584)

Recruiting

Gulfport, Mississippi, United States, 39503

Contacts

Study Coordinator

504-336-2667

Sundance Clinical Research LLC ( Site 0526)

Recruiting

St Louis, Missouri, United States, 63141

Contacts

Study Coordinator

314-567-3377

Methodist Physicians Clinic/CCT Research ( Site 0598)

Recruiting

Fremont, Nebraska, United States, 68025

Contacts

Study Coordinator

402-753-6034

Midwest Regional Health Services, LLC / Avacare ( Site 0603)

Recruiting

Omaha, Nebraska, United States, 68144

Contacts

Study Coordinator

402-778-5490

Excel Clinical Research, LLC ( Site 0566)

Recruiting

Las Vegas, Nevada, United States, 89109

Contacts

Study Coordinator

702-680-1500

Santa Rosa Medical Centers of Nevada / CCT Research ( Site 0605)

Recruiting

Las Vegas, Nevada, United States, 89119

Contacts

Study Coordinator

725-237-2605

DM Clinical Research - Brooklyn ( Site 0550)

Recruiting

Brooklyn, New York, United States, 11226

Contacts

Study Coordinator

929-552-2442

Wilmington Health Associates ( Site 0548)

Recruiting

Wilmington, North Carolina, United States, 28401

Contacts

Study Coordinator

910-815-3262

Wake Forest University Health Sciences ( Site 0569)

Recruiting

Winston-Salem, North Carolina, United States, 27157

Contacts

Study Coordinator

336-716-4584

PriMED Clinical Research ( Site 0560)

Recruiting

Dayton, Ohio, United States, 45429

Contacts

Study Coordinator

937-534-4201

Tekton Research, LLC. ( Site 0601)

Recruiting

Edmond, Oklahoma, United States, 73013

Contacts

Study Coordinator

405-534-5609

DelRicht Research ( Site 0618)

Recruiting

Tulsa, Oklahoma, United States, 74133

Contacts

Study Coordinator

918-932-2276

Liberty Family Practice ( Site 0546)

Recruiting

Erie, Pennsylvania, United States, 16508

Contacts

Study Coordinator

814-868-9828

Tribe Clinical Research, LLC ( Site 0577)

Recruiting

Greenville, South Carolina, United States, 29607

Contacts

Study Coordinator

864-334-0141

Spartanburg Medical Research ( Site 0514)

Recruiting

Spartanburg, South Carolina, United States, 29303

Contacts

Study Coordinator

864-583-1556

DCT-HCWC, LLC dba Discovery Clinical Trials ( Site 0606)

Recruiting

Dallas, Texas, United States, 75230

Contacts

Study Coordinator

817-378-0855

Elevate Clinical Research - Houston ( Site 0589)

Recruiting

Houston, Texas, United States, 77058

Contacts

Study Coordinator

281-282-0808

Research Your Health ( Site 0567)

Recruiting

Plano, Texas, United States, 75093

Contacts

Study Coordinator

972-999-1155

Charlottesville Medical Research ( Site 0559)

Recruiting

Charlottesville, Virginia, United States, 22911

Contacts

Study Coordinator

434-817-2442

Clinical Research Partners, LLC. ( Site 0504)

Recruiting

Richmond, Virginia, United States, 23226

Contacts

Study Coordinator

804-477-3045

More Information

Sponsor

Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA)

Last update posted

Oct 15, 2026

Last verified

Oct, 2026

Keywords

Influenza
Antiviral Agents

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-16. This information was provided to ClinicalTrials.gov by Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) on 2026-10-15. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.