Chronic Hepatitis C VirusPhase 2NCT05904470

A Phase 2, Safety and Efficacy of Bemnifosbuvir (BEM) and Ruzasvir (RZR) in Subjects With Chronic HCV

A Phase 2 study testing Bemnifosbuvir and Ruzasvir in people with Chronic Hepatitis C Virus and Hepatitis C, Chronic, run by Atea Pharmaceuticals, Inc. at 51 sites in 12 countries.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

Search all trials

Trial summary

This is an open-label trial to evaluate safety and efficacy of treatment with BEM + RZR in subjects with chronic HCV infection. Read more about this study

Who is it for?: Ages 18 to 85 years
Conditions the study is for: Chronic Hepatitis C Virus, Hepatitis C, Chronic, Hepatitis C
What is being tested?: Bemnifosbuvir and Ruzasvir
Type of treatment: Pill or oral medicine
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 275 participants
Where: 51 sitesin 12 countries
Study dates: 30 May 2023to 28 Jan 2025
Phase: Phase 2
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 to 85 years
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

Willing and able to provide written informed consent
Male or female subjects between ≥ 18 years of age (or the legal age of consent per local regulations) and ≤ 85 years of age
Female subjects of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or to the use of an acceptable effective contraception
Females must have a negative pregnancy test at Screening and at Day 1 prior to dosing
Subjects must be direct-acting antiviral (DAA)-treatment-naïve, defined as never exposed to an approved or experimental DAA for HCV
Documented medical history compatible with chronic HCV

Show all 9Show fewer

Liver disease staging assessment as follows:
Absence of cirrhosis (F0 to F3)
Compensated cirrhosis (F4)

Who cannot join

Female subject is pregnant or breastfeeding
Co-infected with hepatitis B virus (HBV; positive for hepatitis B surface antigen [HBsAg]) and/or human immunodeficiency virus (HIV)
Abuse of alcohol and/or illicit drug use that could interfere with adherence to study requirements as judged by the investigator
Prior exposure to any HCV DAA
Use of other investigational drugs within 30 days of dosing or plans to enroll in another clinical trial of an investigational agent while participating in the present study
Subject with known allergy to the study medications or any of their components

Show all 10Show fewer

History or signs of decompensated liver disease: ascites, variceal bleeding, hepatic encephalopathy, spontaneous bacterial peritonitis, or other clinical signs of portal hypertension or hepatic insufficiency
Cirrhotic and has a Child-Pugh score >6, corresponding to a Child-Pugh Class B or C
History of hepatocellular carcinoma (HCC) or findings suggestive of possible HCC
Any other clinically significant medical condition that, in the opinion of the investigator, would jeopardize the safety of the subject or impact the validity of the study results

Trial locations and contacts

51 sites in 12 countries.

Country

City, postcode or hospital

51 sites in 12 countries

Brazil14 sites

Atea Study Site
Boa Vista, Roraima, 69304-015
Atea Study Site
Botucatu, São Paulo, 18618-970
Atea Study Site
Brasília, Federal District, 70200-730
Atea Study Site
Ijuí, São Paulo, 98700-000
Atea Study Site
Manaus, Amazonas, 69040-000
Atea Study Site
Porto Alegre, Rio Grande do Sul, 90035-074
Atea Study Site
Porto Alegre, Rio Grande do Sul, 90035-903
Atea Study Site
Porto Velho, Rondônia, 78918-791
Atea Study Site
Rio de Janeiro, Rio Do Janeiro, 04037-030
Atea Study Site
Salvador, Estado de Bahia, 41920-900
Atea Study Site
São José do Rio Preto, São Paulo, 15090-000
Atea Study Site
São Paulo, São Paulo, 04119-001
Atea Study Site
São Paulo, São Paulo, 05403-000
Atea Study Site
Sorocaba, São Paulo, 18052-210

Other trials in Brazil

Turkey (Türkiye)7 sites

Atea Study Site
Adana, 1130
Atea Study Site
Ankara, 6100
Atea Study Site
Ankara, 6230
Atea Study Site
Ankara, 6800
Atea Study Site
Denizli, 20070
Atea Study Site
Izmir, 35100
Atea Study Site
Kayseri, 38010

Other trials in Turkey (Türkiye)

South Korea6 sites

Atea Study Site
Busan, 47392
Atea Study Site
Busan, 49241
Atea Study Site
Seoul, Gyeonggi-do, 120-752
Atea Study Site
Seoul, 5505
Atea Study Site
Seoul, 6351
Atea Study Site
Yangsan, Gyeongsangnam, 626-770

Other trials in South Korea

India5 sites

Atea Study Site
Belagavi, Karnataka, 590010
Atea Study Site
Kolkata, West Bengal, 700020
Atea Study Site
Nagpur, Maharashtra, 440010
Atea Study Site
Rajkot, Gujarat, 360005
Atea Study Site
Surat, Gujarat, 395002

Other trials in India

Romania5 sites

Atea Study Site
Bucharest, BUC, 022328
Atea Study Site
Bucharest, BUC, 30303
Atea Study Site
Bucharest, 21105
Atea Study Site
Constanța, CON, 900709
Atea Study Site
Craiova, DOL, 200073

Other trials in Romania

South Africa4 sites

Atea Study Site
Bloemfontein, Free State, 9301
Atea Study Site
Johannesburg, Gauteng, 2193
Atea Study Site
Randburg, Gauteng, 2087
Atea Study Site
Somerset West, Western Cap, 7130

Other trials in South Africa

Philippines3 sites

Atea Study Site
Baguio City, 35100
Atea Study Site
Iloilo City, 5000
Atea Study Site
Mabalacat, 2023

Other trials in Philippines

Canada2 sites

Atea Study Site
Toronto, Ontario, M5G 2C4
Atea Study Site
Vancouver, British Columbia, V6Z 2C7

Other trials in Canada

Pakistan2 sites

Atea Study Site
Karachi, 74800
Atea Study Site
Karachi, 75600

Other trials in Pakistan

United States1 site

Atea Study Site
San Antonio, Texas, 78215

Other trials in United States

Mauritius1 site

Atea Study Site
Quatre Bornes, 72218

Other trials in Mauritius

Moldova1 site

Atea Study Site
Chisinau, 2025

Other trials in Moldova

About this study

Official title: A Phase 2, Open-label Study to Assess the Safety and Efficacy of Bemnifosbuvir (BEM) and Ruzasvir (RZR) in Subjects With Chronic Hepatitis C Virus (HCV) Infection

This is an open-label trial to evaluate safety and efficacy of treatment with BEM + RZR in subjects with chronic HCV infection.

Conditions: Chronic Hepatitis C Virus, Hepatitis C, Chronic, Hepatitis C, Hepatic Cirrhosis, HCV
Being tested: Bemnifosbuvir, Ruzasvir
Medical subject headings: Hepatitis C, Chronic, Hepatitis C, Liver Cirrhosis

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

BemnifosbuvirDrug
Also called AT-527
550 mg administered orally once a day (QD) for 8 weeks
RuzasvirDrug
Also called AT-038
180 mg administered orally once a day (QD) for 8 weeks

Study groups in NCT05904470
Study group	Role	What they receive
Bemnifosbuvir and Ruzasvir	Experimental	Bemnifosbuvir (BEM; AT-527) Tablets Ruzasvir (RZR; AT-038) Capsules Receives: Drug: Bemnifosbuvir; Drug: Ruzasvir

What is being measured

The primary outcome is the main question the study is designed to answer.

Percentage of Subjects Achieving Sustained Virologic Response at 12 Weeks Post-treatment (SVR12)
SVR12 defined as plasma hepatitis C virus (HCV) RNA less than the lower limit of quantitation (<LLOQ) at 12 weeks post-treatment
Measured: Day 1 through 12 weeks after end of treatment

Secondary outcomes (2)

Percentage of Subjects Experiencing Virologic Failure
Virologic failure defined as a confirmed 1 log10 increase in HCV RNA from post-baseline nadir, or confirmed increase in HCV RNA ≥ LLOQ in any subject who achieved HCV RNA < LLOQ.
Measured: Day 1 through 12 weeks after end of treatment
Percentage of Subjects Achieving Sustained Virologic Response at 24 Weeks Post-treatment (SVR24)
SVR24 defined as plasma HCV RNA less than the lower limit of quantitation (<LLOQ) at 24 weeks post-treatment
Measured: Day 1 through 24 weeks after end of treatment

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

30 May 202328 Jan 2025

First posted15 Jun 2023
Study start30 May 2023
Primary completion9 Dec 2024
Study completion28 Jan 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Other trials for Chronic Hepatitis C VirusStudies of the same condition, open and under way.
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: Not applicable
Intervention model: Single group
Masking: None (open label)
Enrolment: 275 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05904470
Sponsor's protocol ID: AT-01B-004
Status last verified: Oct 2025
First submitted: 6 Jun 2023
Last updated: 21 Oct 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

RecruitingObservational study
Evaluation of Patients With Liver Disease
Hepatitis D, Hepatitis C
Active, not recruitingPhase 4
People With CHC Who Achieved a Sustained Virological Response Following Therapy With Direct Acting Antiviral Agents
Diabetes Mellitus, Hepatitis C, Chronic
RecruitingObservational study
"Constitution of a Biological Collection to Establish Preclinical Translational Models for the Study of Tumors and Chronic Liver Diseases".
Chronic Liver Disease and Cirrhosis, Liver Cancer
Active, not recruitingPhase 4
Sofosbuvir/Velpatasvir Treatment of Chronic Hepatitis C During Pregnancy
Hepatitis C, Chronic, Pregnancy; Infection
Enrolling by invitationObservational study
Comparative Autoantibody and Immunologic Cell Marker Study
Autoimmune Diseases, Lupus Erythematosus, Systemic

All Chronic Hepatitis C Virus trials

Study at a glance

From the registry record, last updated by the sponsor on 21 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 2, Open-label Study to Assess the Safety and Efficacy of Bemnifosbuvir (BEM) and Ruzasvir (RZR) in Subjects With Chronic Hepatitis C Virus (HCV) Infection
ClinicalTrials.gov ID: NCT05904470
Acronym / sponsor ID: AT-01B-004
Conditions: Chronic Hepatitis C Virus, Hepatitis C, Chronic, Hepatitis C, Hepatic Cirrhosis, HCV
Phase: Phase 2
Study type: Interventional
Recruitment status: Completed
Enrolment: 275 participants (actual)
Lead sponsor: Atea Pharmaceuticals, Inc.Industry (pharma, biotech, devices)
Study start: 30 May 2023 (actual)
Primary completion: 9 Dec 2024 (actual)
Study completion: 28 Jan 2025 (actual)
First posted: 15 Jun 2023 (actual)
Results: Posted 21 Oct 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

This is an open-label trial to evaluate safety and efficacy of treatment with BEM + RZR in subjects with chronic HCV infection.

Study design

Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Number of arms: 1

Arm	Type	Receives
Bemnifosbuvir and Ruzasvir	Experimental	Drug: Bemnifosbuvir, Drug: RuzasvirBemnifosbuvir (BEM; AT-527) Tablets Ruzasvir (RZR; AT-038) Capsules

Who may qualify

Ages: 18 to 85 years
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (9 listed)

Willing and able to provide written informed consent
Male or female subjects between ≥ 18 years of age (or the legal age of consent per local regulations) and ≤ 85 years of age
Female subjects of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or to the use of an acceptable effective contraception
Females must have a negative pregnancy test at Screening and at Day 1 prior to dosing
Subjects must be direct-acting antiviral (DAA)-treatment-naïve, defined as never exposed to an approved or experimental DAA for HCV

Key exclusion criteria (10 listed)

Female subject is pregnant or breastfeeding
Co-infected with hepatitis B virus (HBV; positive for hepatitis B surface antigen [HBsAg]) and/or human immunodeficiency virus (HIV)
Abuse of alcohol and/or illicit drug use that could interfere with adherence to study requirements as judged by the investigator
Prior exposure to any HCV DAA
Use of other investigational drugs within 30 days of dosing or plans to enroll in another clinical trial of an investigational agent while participating in the present study

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
BemnifosbuvirAlso: AT-527550 mg administered orally once a day (QD) for 8 weeks	Drug	Bemnifosbuvir and Ruzasvir
RuzasvirAlso: AT-038180 mg administered orally once a day (QD) for 8 weeks	Drug	Bemnifosbuvir and Ruzasvir

Primary outcome

Percentage of Subjects Achieving Sustained Virologic Response at 12 Weeks Post-treatment (SVR12)
Time frame: Day 1 through 12 weeks after end of treatment
SVR12 defined as plasma hepatitis C virus (HCV) RNA less than the lower limit of quantitation (<LLOQ) at 12 weeks post-treatment

2 secondary outcomes

Percentage of Subjects Experiencing Virologic Failure
Time frame: Day 1 through 12 weeks after end of treatment
Percentage of Subjects Achieving Sustained Virologic Response at 24 Weeks Post-treatment (SVR24)
Time frame: Day 1 through 24 weeks after end of treatment

Results and safety

Results posted to the registry on 21 Oct 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
BEM+RZR	275	255

Primary outcome: Percentage of Subjects Achieving Sustained Virologic Response at 12 Weeks Post-treatment (SVR12)

Time frame: Day 1 through 12 weeks after end of treatment. Count of participants. Unit: Participants

Measure	BEM+RZR n = 215
Value	210

Population analysed: The primary per-protocol analysis population included subjects who met all eligibility criteria, completed treatment (defined as being ≥90% compliant with the study drug regimen), had outcomes at post-treatment week 12, and had adequate study-drug exposure corroborated by pill counts and plasma drug levels adjudicated by an independent clinical pharmacologist.

2 secondary outcomes are reported in the full results.

Adverse events

Time frame: Treatment-emergent adverse events were collected through 4 weeks post-treatment and serious adverse events were collected through 24 weeks post-treatment.. Other adverse events reported at 2% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
BEM+RZR	19 of 275 (6.9%)	64 of 275 (23.3%)	5 of 275

Limitations and caveats (from the sponsor): This was a single arm study. Results will need to be confirmed in larger, controlled randomized trials.

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 21 Oct 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.

Related trials for Chronic Hepatitis C Virus

RecruitingObservational study
Evaluation of Patients With Liver Disease
Hepatitis D, Hepatitis C
Active, not recruitingPhase 4
People With CHC Who Achieved a Sustained Virological Response Following Therapy With Direct Acting Antiviral Agents
Diabetes Mellitus, Hepatitis C, Chronic
RecruitingObservational study
"Constitution of a Biological Collection to Establish Preclinical Translational Models for the Study of Tumors and Chronic Liver Diseases".
Chronic Liver Disease and Cirrhosis, Liver Cancer
Active, not recruitingPhase 4
Sofosbuvir/Velpatasvir Treatment of Chronic Hepatitis C During Pregnancy
Hepatitis C, Chronic, Pregnancy; Infection
Enrolling by invitationObservational study
Comparative Autoantibody and Immunologic Cell Marker Study
Autoimmune Diseases, Lupus Erythematosus, Systemic

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

51 sites in 12 countries: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Bemnifosbuvir and Ruzasvir in people with Chronic Hepatitis C Virus and Hepatitis C, Chronic, run by Atea Pharmaceuticals, Inc. at 51 sites in 12 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 9 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 21 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 51 sites in Brazil, Turkey (Türkiye), South Korea, India, Romania and 7 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 21 Oct 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of Subjects Achieving Sustained Virologic Response at 12 Weeks Post-treatment (SVR12) (time frame: Day 1 through 12 weeks after end of treatment). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05904470.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Oct 2025.