Respiratory Syncytial Virus InfectionsPhase 2NCT07214571
A Study of S-337395 in Symptomatic Nonhospitalized Adults With Respiratory Syncytial Virus (RSV) Who Are at High Risk of Progression to Severe Disease
A Phase 2 study testing S-337395 in people with Respiratory Syncytial Virus Infections, run by Shionogi at 89 sites in 8 countries.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Respiratory Syncytial Virus Infections
- What is being tested?
- S-337395
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 192 participants
- Where
- 89 sitesin 8 countries
- Study dates
- 11 Dec 2025to 30 Dec 2026
- Phase
- Phase 2
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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:
- ≥ 75 years of age;
- Chronic lung disease that is symptomatic and requiring chronic treatment; and
- 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.
Who cannot join
- 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.
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- 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.
Trial locations and contacts
89 sites in 8 countries. Contact the study team or a site near you to ask about taking part.
Shionogi Clinical Trials Administrator Clinical Support Help Line contact
89 sites in 8 countries
United States37 sites, 36 recruiting
- Recruiting
Beth Israel Deaconess Medical Center
Boston, Massachusetts, 02215
- Recruiting
Epic Medical Research - Chickasha
Chickasha, Oklahoma, 73018-2738
- Recruiting
University Hospitals Cleveland Medical Center
Cleveland, Ohio, 44106
- Recruiting
Hope Clinical Trials - 3970 W Flagler St.
Coral Gables, Florida, 33134-1642
- Recruiting
Beautiful Minds Clinical Research Center
Cutler Bay, Florida, 33157
- Recruiting
Epic Med. Research LLC, DeSoto
DeSoto, Texas, 75115-2043
- Recruiting
Covenant Pulmonary Criticial Care and Research Ins
East Point, Georgia, 30344-3604
- Recruiting
Doral Medical Research
Hialeah, Florida, 33016-1897
- Recruiting
Clay Platte Family Medicine - CCT Research
Kansas City, Missouri, 64151-2411
- Recruiting
LA Universal Research Center, Inc.
Los Angeles, California, 900057-4040
- Recruiting
DCT-McAllen Primary Care Research, LLC
McAllen, Texas, 78503
- Recruiting
SMS Clinical Research, LLC - 400 W. Kearney St
Mesquite, Texas, 751497
- Recruiting
Southern Clinical Research
Miami, Florida, 33125-4106
- Recruiting
LCC Medical Research - Miami - BTC - PPDS
Miami, Florida, 33126
- Recruiting
Global Health Clinical Trials
Miami, Florida, 33135-2961
- Recruiting
Nuren Medical and Research Center
Miami, Florida, 33144-2069
- Recruiting
Continental Clinical Research, LLC
Miami, Florida, 33144-4273
- Withdrawn
Dynamic Medical Research, LLC - Miami
Miami, Florida, 33144
- Recruiting
Miami Clinical Research, LLP.
Miami, Florida, 33155
- Recruiting
Reed Medical Research
Miami, Florida, 33176-8709
- Recruiting
Palm Springs Community Health Center
Miami Lakes, Florida, 33014-2266
- Recruiting
Central Valley Research
Modesto, California, 95350
- Recruiting
Frontier Clinical Research Waterfront
Morgantown, West Virginia, 26501
- Recruiting
Oceanic Research Group, LLC
North Miami Beach, Florida, 33169-5513
- Recruiting
CDC Research Institute, LLC
Port Saint Lucie, Florida, 34952-7539
- Recruiting
Rhode Island Hospital
Providence, Rhode Island, 02903-4923
- Recruiting
Clinical Research Partners LLC
Richmond, Virginia, 23226-3786
- Recruiting
Cordova Research Insittute
Sweetwater, Florida, 33182
- Recruiting
Better Life Clinical Research LLC
Tampa, Florida, 33607
- Recruiting
Research Bay,Inc.
Tampa, Florida, 33607
- Recruiting
Santos Research Center - 5927 Webb Rd
Tampa, Florida, 33615-3219
- Recruiting
Angels Clinical Research Institute Tampa-Palm Springs
Tampa, Florida, 336214-2869
- Recruiting
NYC Health + Hospitals/Lincoln Medical Center - BRANY - PPDS
The Bronx, New York, 10451
- Recruiting
Prime Global Research, Inc.
The Bronx, New York, 10456-2102
- Recruiting
Med Partnes, Inc - Elligo- PPDS
Toluca Lake, California, 91602-3457
- Recruiting
Progressive Medicine of the Triad, LLC
Winston-Salem, North Carolina, 27103
- Recruiting
University of Massachusetts
Worcester, Massachusetts, 01655
Japan29 sites, 29 recruiting
- Recruiting
Yamaichi Building Internal Medicine Clinic
Adachi-Ku, Tokyo, 03-884-8888
- Recruiting
Doi Clinic
Chikushino-shi, Fukuoka, 092-926-7415
- Recruiting
Ebino Centro Clinic
Ebino, Miyazaki, 0984-33-5777
- Recruiting
Irie Clinic
Fukuoka, Fukuoka, 092-651-4521
- Recruiting
Tomita Internal Medicine Clinic
Fukuoka-Shi Chuo-Ku, Fukuoka, 092-707-2103
- Recruiting
PS Clinic
Fukuoka-Shi Hakata-Ku, Fukuoka, 092-283-7777
- Recruiting
Kijima Kids Clinic
Higashiokitama-gun, Yamagata, 0238-54-0135
- Recruiting
Terada Internal Medicine and Respiratory Department
Himeji-shi, Hyôgo, 079-285-0111
- Recruiting
Toda Internal Medicine and Neurology
Hyōgo, 078-947-5575
- Recruiting
Rinku General Medical Center
Izumisano, Osaka, 072-469-3111
- Recruiting
Kamezawa Clinic
Kasugai-Shi, Aiti, 0568-56-5050
- Recruiting
Medical Corporation Hosoda Clinic
Katsushika-ku, Tokyo, 03-3657-3430
- Recruiting
Medical corporation Kojinkai Takahashi Internal Medicine
Kawasaki-Shi, Kanagawa, 044-740-2717
- Recruiting
Social Medical Corporation the Chiyukai foundation Shin Komonji Hospital
Kitakyushu-Shi, Fukuoka, 093-391-1001
- Recruiting
Medical corporation Aimeikai Morizono internal medicine
Kitakyushu-Shi Yahatanishi-Ku, Fukuoka, 093-611-5335
- Recruiting
Medical Corporation Shirayurikai Swing Building Nozaki Clinic
Musashino, Tokyo, 0422-36-3534
- Recruiting
Hosokawa Surgical Clinic
Nagoya-Shi Nakamura-Ku, Aiti, 052-481-9921
- Recruiting
Nogata Clinic
Nakano-ku, Tokyo, 03-3389-2201
- Recruiting
Noguchi Internal Medicine Clinic
Nakano-Ku, Tokyo, 03-3926-0007
- Recruiting
Social medical corporation Keiwakai Nishioka Hospital
Sapporo-Shi Toyohira-Ku, Hokkaidô, 011-853-8322
- Recruiting
Sato Clinic
Shibuya-Ku, Tokyo, 03-5447-2477
- Recruiting
Mih Clinic Yoyogi
Shibuya-Ku, Tokyo, 03-6276-5385
- Recruiting
Medical corporation Hiroyukai Yotsuya Internal Medicine
Shinjuku-Ku, Tokyo, 03-5368-0675
- Recruiting
Shiwa Central Pediatrics
Shiwa-gun, Iwate, 019-672-1110
- Recruiting
Yoshida Clinic
Suginami-ku, Tokyo, 03-5347-7300
- Recruiting
Shizuka Clinic
Takasaki-shi, Gunma, 027-370-0777
- Recruiting
Sekino Hospital
Toshima-Ku, Tokyo, 03-3986-5501
- Recruiting
Tsuchiura Beryl Clinic
Tsuchiura-Shi, Ibaraki, 029-835-3002
- Recruiting
Gajyumaru Clinic Tsukuba
Tsukuba, Ibaraki, 029-893-4159
Argentina6 sites, 6 recruiting
- Recruiting
Fundación Huésped - PPDS
CABA, Buenos Aires, C1427CEA
- Recruiting
AES - AS - Glenny Corp. S.A. Buenos Aires
CABA, Buenos Aires, C1430CKE
- Recruiting
CEMLO - Centro de Especialidades Médicas
Lobos, Buenos Aires, C7240
- Recruiting
Instituto Médico Río Cuarto
Río Cuarto, Córdoba Province, X5800AEV
- Recruiting
Instituto De Enfermedades Respiratorias E Investigación Médica - IERIM
San Juan Bautista, Buenos Aires, 1888
- Recruiting
AES - AS - Clinica Mayo de Urgencias
San Miguel de Tucumán, Tucumán Province, T4000IHE
Bulgaria5 sites, 5 recruiting
- Recruiting
Multiprofile Hospital For Active Treatment Dr Tota Venkova - PRATIA - PPDS
Gabrovo, 5300
- Recruiting
MCpulmo-2018 Ltd
Haskovo, 6300
- Recruiting
Medical Center Hera EOOD, Montana
Montana, Sofia, 3400
- Recruiting
Medical Center Hera EOOD
Sofia, 1510
- Recruiting
Medical Center Neuromedics EOOD - 4 Veliki Preslav Str
Veliko Tarnovo, 5005
South Africa4 sites, 4 recruiting
- Recruiting
Newtown Clinical Research Centre
Johannesburg, Gauteng, 2001
- Recruiting
Be Part Yoluntu Centre
Paarl, Western Cape, 7655
- Recruiting
Roodepoort Medicross Clinical Research Centre
Princess Crossing, Roodepoort, 1724
- Recruiting
The Aurum Institute Rustenburg Clinical Research Site
Rustenburg, 2999
Poland3 sites, 3 recruiting
- Recruiting
Centrum Medyczne Chojnice - PRATIA - PPDS
Chojncie, Pomeranian Voivodeship, 86-900
- Recruiting
Ostrowieckie Centrum Medyczne Spólka Cywilna Anna Olech-Cudzik, Krzysztof Cudzik
Ostrowiec Świętokrzyski, Świętokrzyskie Voivodeship, 27-400
- Recruiting
Alergo-Med Osrodek Badan Klinicznych sp z o.o
Tarnów, Lesser Poland Voivodeship, 33-100
Taiwan3 sites, 3 recruiting
- Recruiting
Kaohsiung Veterans General Hospital
Kaohsiung City, 813414
- Recruiting
Kaohsiung Medical University - Chung-Ho Memorial Hospital
Kaohsiung City
- Recruiting
Tri-Service General Hospital
Neihu District, Taipei, 114202
Vietnam2 sites, 2 recruiting
- Recruiting
Hanoi Medical University Hospital
Hà Nội, 100000
- Recruiting
University of Medicine and Pharmacy
Ho Chi Minh City, 700000
About this study
Official title: A Phase 2b, Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel-group Study to Evaluate the Safety, Tolerability, and Efficacy of S-337395 in Symptomatic Nonhospitalized Adults With Respiratory Syncytial Virus Who Are at High Risk of Progression to Severe Disease
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
- Being tested
- S-337395, Placebo
- Keywords
- Respiratory Syncytial Virus Infections, RSV infection, Viral infection, S-337395, Acute lower respiratory tract infection
- Medical subject headings
- Respiratory Syncytial Virus Infections, Virus Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
S-337395Drug
S-337395 will be administered per schedule specified in the arm description.
PlaceboDrug
Placebo matched to S-337395 will be administered per schedule specified in the arm description.
| Study group | Role | What they receive |
|---|---|---|
| S-337395 High Dose | Experimental | Participants will receive a high dose of S-337395 twice daily (BID) orally for up to 5 days. Receives: Drug: S-337395 |
| S-337395 Low Dose | Experimental | Participants will receive a low dose of S-337395 BID orally for up to 5 days. Receives: Drug: S-337395 |
| Placebo | Placebo comparator | Participants will receive matching placebo BID orally for 5 days. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change From Baseline in RSV Ribonucleic Acid (RNA) Load by Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) (Nasopharyngeal Swab) at Day 2
Measured: Baseline, Day 2
Change From Baseline in RSV RNA Load by qRT-PCR (Nasopharyngeal Swab) at Day 4
Measured: Baseline, Day 4
Change From Baseline in RSV RNA Load by qRT-PCR (Nasopharyngeal Swab) at Day 6
Measured: Baseline, Day 6
Secondary outcomes (30)
Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Measured: Day 1 up to Day 28
Change From Baseline in Severity of RSV Respiratory Symptom Score Based on the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) Respiratory Symptom Subscale (RiiQ-RSS)
Measured: Baseline up to Day 6
Change From Baseline in Severity of RSV Systemic Symptoms Score Based on the RiiQ Systemic Symptom Subscale (RiiQ-SSS)
Measured: Baseline up to Day 6
Change From Baseline in Severity of RSV Total Symptoms Score Based on the Combined RiiQ RSS and RiiQ-SSS
Measured: Baseline up to Day 6
Time to First Resolution of All Respiratory RSV-related Symptoms Based on the RiiQ-RSS
Measured: Baseline up to Day 6
Time to Sustained (2 Consecutive Days) Resolution of All Respiratory RSV-related Symptoms Based on the RiiQ-RSS
Measured: Baseline up to Day 6
Time to First Resolution of All Systemic RSV-related Symptoms Based on the RiiQ-SSS
Measured: Baseline up to Day 6
Time to Sustained Resolution of All Systemic RSV-related Symptoms Based on the RiiQ-SSS
Measured: Baseline up to Day 6
Time to First Resolution of All Respiratory and Systemic RSV-related Symptoms Based on the Combined RiiQ RSS and RiiQ-SSS
Measured: Baseline up to Day 6
Time to Sustained Resolution of All Respiratory and Systemic RSV-related Symptoms Based on the Combined RiiQ RSS and RiiQ-SSS
Measured: Baseline up to Day 6
Time to First Resolution of Each Separate RSV-related Symptom Based on the RiiQ Symptom Subscale
Measured: Baseline up to Day 6
Time to Sustained Resolution of Each Separate RSV-related Symptom Based on the RiiQ Symptom Subscale
Measured: Baseline up to Day 6
Change From Baseline in RSV RNA Load
Measured: Baseline up to Day 6
Area Under the Curve (AUC) of Change From Baseline in RSV RNA Load
Measured: Baseline up to Day 6
Time to the First Negative RSV RNA Load by qRT-PCR
Measured: Baseline up to Day 6
Time to Sustained Negative RSV RNA Load by qRT-PCR
Measured: Baseline up to Day 6
Percentage of Participants With Negative RSV RNA Load by qRT-PCR
Measured: Baseline up to Day 6
Time to the First RSV RNA Load <Lower Limit of Quantitation (LLOQ)
Measured: Baseline up to Day 6
Time to Sustained RSV RNA Load <LLOQ
Measured: Baseline up to Day 6
Percentage of Participants With RSV RNA Load <LLOQ
Measured: Baseline up to Day 6
Change From Baseline in Infectious Titer
Measured: Baseline up to Day 6
AUC of Change From Baseline in Infectious Titer
Measured: Baseline up to Day 6
Time to the First Negative RSV Infectious Titer
Measured: Baseline up to Day 6
Time to Sustained Negative RSV Infectious Titer
Measured: Baseline up to Day 6
Percentage of Participants With Negative RSV Infectious Titer
Measured: Baseline up to Day 6
Time to the First RSV Infectious Titer <LLOQ
Measured: Baseline up to Day 6
Time to Sustained RSV Infectious Titer <LLOQ
Measured: Baseline up to Day 6
Percentage of Participants With RSV Infectious Titer <LLOQ
Measured: Baseline up to Day 6
Plasma Concentration of S-337395 After Repeated Oral Doses of S-337395
Measured: Baseline up to Day 6
Plasma Concentration of S-337395 12 and 24 Hours After the First Dose and the Last Dose (C12 and C24)
Measured: 12 hours and 24 hours after first dose (Day 2) and last dose (Day 6)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Oct 2025
- Study start11 Dec 2025
- Primary completion30 Dec 2026 (estimated)
- Study completion30 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Respiratory Syncytial Virus InfectionsStudies of the same condition, open and under way.
- More trials run by ShionogiThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 192 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Shionogi
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07214571
- Sponsor's protocol ID
- 2402T1432
- Status last verified
- Oct 2026
- First submitted
- 8 Oct 2025
- Last updated
- 21 Oct 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No