Protective shot against flu: MK-1406 (CD388) given as a one-time dose to teens and adults at higher risk

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This is a Phase 3, randomized, double-blind, placebo-controlled trial conducted at multiple centers to evaluate the safety and efficacy of a single-dose MK-1406 (CD388) given by subcutaneous injections. Participants are adolescents and adults at increased risk of influenza complications and are assigned to MK-1406 or placebo in parallel groups. The study assesses whether the treatment can reduce influenza occurrence and severity, while monitoring safety and tolerability. Inclusion covers non-immunocompromised individuals with chronic conditions and immunocompromised individuals with varying risk factors, with dosing occurring after pre-dose testing. Locations include sites in Alabama and Arizona under lead sponsor Cidara Therapeutics/Merck collaboration.

Why it matters

Who can join: the full rules

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)

Where it's running

• Pinnacle Research Group ( Site 0505)
  Anniston, Alabama, United States Recruiting
• Cullman Clinical Trials ( Site 0538)
  Cullman, Alabama, United States Recruiting
• Hope Research Institute ( Site 0575)
  Glendale, Arizona, United States Recruiting
• Hope Research Institute ( Site 0587)
  Tempe, Arizona, United States Recruiting
• Del Sol Research Management, LLC ( Site 0515)
  Tucson, Arizona, United States Recruiting
• Profound Research LLC ( Site 0743)
  Carlsbad, California, United States Recruiting

+161 more sites. See ClinicalTrials.gov for the full list.

Study contacts

• Study coordinator: Toll Free Number
• Email: Trialsites@msd.com
• Phone: 1-888-577-8839

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.