Recruiting
Phase 2

S-337395

Sponsor:

Shionogi

Code:

NCT07214571

Conditions

Respiratory Syncytial Virus Infections

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

S-337395

Placebo

Study Details

Brief summary:

The main purpose of this study is to investigate the antiviral effect of S-337395 compared with placebo among nonhospitalized adult participants with high-risk factors for progression to severe RSV infection starting intervention within 72 hours of RSV symptom onset.

Conditions

Respiratory Syncytial Virus Infections

Study ID

NCT07214571

Start date

Dec 11, 2025

Status verified date

Aug, 2026

Completion date

Dec 30, 2026

Anticipated

Primary completion date

Dec 30, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Key Inclusion Criteria:

  • Participants who have new onset or worsening (if present chronically) of at least 1 of the following signs and/or symptoms consistent with a viral acute respiratory infection within 72 hours prior to randomization: fever, nasal congestion, nasal discharge, sore throat, cough, sputum production, shortness of breath, or wheezing.
  • Participants diagnosed with RSV infection preferably using a rapid polymerase chain reaction (PCR) or other molecular-based diagnostic assay.
  • Has at least 1 of the following risk factors for severe RSV disease:

1. ≥ 75 years of age;
2. Chronic lung disease that is symptomatic and requiring chronic treatment; and
3. Chronic cardiovascular disease that is symptomatic and requiring chronic treatment.
  • With the exception of the RSV disease, medically stable on the basis of medical history, physical examination, vital signs, and 12-lead electrocardiogram (ECG) performed at screening.

Key Exclusion Criteria:

  • Hospitalized or expected to be hospitalized within 24 hours of screening.
  • Is considered by the investigator to be immunocompromised, due to an underlying medical condition or medical therapy, chemotherapy, radiation, stem cell or solid organ transplant.
  • Has known allergies, hypersensitivity, or intolerance to S-337395 or to any of the excipients of the S-337395 or placebo formulation.
  • Suspicion or known severe renal impairment.
  • Any other medical or psychiatric condition making the participant unsuitable for the current study or interfering with the evaluation of response to the study intervention in the opinion of the investigator/subinvestigator.
  • Has received a therapy intended to treat RSV infection within 14 days prior to screening.
  • Is receiving chemotherapy or immunotherapy for malignancy.
  • Has received RSV vaccination within 7 days prior to screening.
  • Has had either confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or influenza infection (test was positive) during the 28 days prior to screening.
  • Has any other confirmed clinically relevant respiratory infection by any pathogen at, or within 28 days of screening.

Note: Other protocol-specified inclusion and exclusion criteria may apply.

Study Design

Enrollment

192 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: S-337395 High Dose

Participants will receive a high dose of S-337395 twice daily (BID) orally for up to 5 days.

experimental: S-337395 Low Dose

Participants will receive a low dose of S-337395 BID orally for up to 5 days.

placebo comparator: Placebo

Participants will receive matching placebo BID orally for 5 days.

Interventions

S-337395

S-337395 will be administered per schedule specified in the arm description.

Placebo

Placebo matched to S-337395 will be administered per schedule specified in the arm description.

Primary outcome measure

  • Change From Baseline in RSV Ribonucleic Acid (RNA) Load by Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) (Nasopharyngeal Swab) at Day 2 [ Time Frame: Baseline, Day 2 ]
  • Change From Baseline in RSV RNA Load by qRT-PCR (Nasopharyngeal Swab) at Day 4 [ Time Frame: Baseline, Day 4 ]
  • Change From Baseline in RSV RNA Load by qRT-PCR (Nasopharyngeal Swab) at Day 6 [ Time Frame: Baseline, Day 6 ]

Central Contacts and Locations

Central contacts

Shionogi Clinical Trials Administrator Clinical Support Help Line

800-849-9707Shionogiclintrials-admin@shionogi.co.jp

Locations

LA Universal Research Center, Inc.

Recruiting

Los Angeles, California, United States, 900057-4040

Central Valley Research

Recruiting

Modesto, California, United States, 95350

Med Partnes, Inc - Elligo- PPDS

Recruiting

Toluca Lake, California, United States, 91602-3457

Hope Clinical Trials - 3970 W Flagler St.

Recruiting

Coral Gables, Florida, United States, 33134-1642

Beautiful Minds Clinical Research Center

Recruiting

Cutler Bay, Florida, United States, 33157

Doral Medical Research

Recruiting

Hialeah, Florida, United States, 33016-1897

Southern Clinical Research

Recruiting

Miami, Florida, United States, 33125-4106

LCC Medical Research - Miami - BTC - PPDS

Recruiting

Miami, Florida, United States, 33126

Global Health Clinical Trials

Recruiting

Miami, Florida, United States, 33135-2961

Nuren Medical and Research Center

Recruiting

Miami, Florida, United States, 33144-2069

Continental Clinical Research, LLC

Recruiting

Miami, Florida, United States, 33144-4273

Miami Clinical Research, LLP.

Recruiting

Miami, Florida, United States, 33155

Reed Medical Research

Recruiting

Miami, Florida, United States, 33176-8709

Palm Springs Community Health Center

Recruiting

Miami Lakes, Florida, United States, 33014-2266

Oceanic Research Group, LLC

Recruiting

North Miami Beach, Florida, United States, 33169-5513

CDC Research Institute, LLC

Recruiting

Port Saint Lucie, Florida, United States, 34952-7539

Cordova Research Insittute

Recruiting

Sweetwater, Florida, United States, 33182

Better Life Clinical Research LLC

Recruiting

Tampa, Florida, United States, 33607

Research Bay,Inc.

Recruiting

Tampa, Florida, United States, 33607

Santos Research Center - 5927 Webb Rd

Recruiting

Tampa, Florida, United States, 33615-3219

Angels Clinical Research Institute Tampa-Palm Springs

Recruiting

Tampa, Florida, United States, 336214-2869

Covenant Pulmonary Criticial Care and Research Ins

Recruiting

East Point, Georgia, United States, 30344-3604

Beth Israel Deaconess Medical Center

Recruiting

Boston, Massachusetts, United States, 02215

Clay Platte Family Medicine - CCT Research

Recruiting

Kansas City, Missouri, United States, 64151-2411

NYC Health + Hospitals/Lincoln Medical Center - BRANY - PPDS

Recruiting

The Bronx, New York, United States, 10451

Prime Global Research, Inc.

Recruiting

The Bronx, New York, United States, 10456-2102

Progressive Medicine of the Triad, LLC

Recruiting

Winston-Salem, North Carolina, United States, 27103

University Hospitals Cleveland Medical Center

Recruiting

Cleveland, Ohio, United States, 44106

Epic Medical Research - Chickasha

Recruiting

Chickasha, Oklahoma, United States, 73018-2738

Rhode Island Hospital

Recruiting

Providence, Rhode Island, United States, 02903-4923

Epic Med. Research LLC, DeSoto

Recruiting

DeSoto, Texas, United States, 75115-2043

DCT-McAllen Primary Care Research, LLC

Recruiting

McAllen, Texas, United States, 78503

SMS Clinical Research, LLC - 400 W. Kearney St

Recruiting

Mesquite, Texas, United States, 751497

Clinical Research Partners LLC

Recruiting

Richmond, Virginia, United States, 23226-3786

Frontier Clinical Research Waterfront

Recruiting

Morgantown, West Virginia, United States, 26501

More Information

Sponsor

Shionogi

Last update posted

Aug 11, 2026

Last verified

Aug, 2026

Keywords

  • Respiratory Syncytial Virus Infections
  • RSV infection
  • Viral infection
  • S-337395
  • Acute lower respiratory tract infection

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Shionogi on 2026-08-11.