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Tobevibart

Phase 3

Viral Hepatitis | Small molecule | Infectious Disease |Vir Biotechnology, Inc.|Trials Updated: Jul 13, 2026

Tobevibart development status

Highest phase Phase 3
Registered trials 9 across 2 sponsors since Jun 2020

Tobevibart target and mechanism

Molecular targetHBsAg
ModalitySmall molecule

Also known as VIR-3434, BRII-877

Success Probability

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Market & Valuation

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Trial Design

RandomizedCONTROLLEDDMC
Total Trials5
Total Enrollment520

FDA Designations

No designations recorded

Tobevibart clinical trials

Tobevibart · 5 trials · 3 indications

Phase 3 2Phase 2 1Phase 1 2
NCT07128550A Study to Evaluate Tobevibart+Elebsiran in Participants With Chronic HDV Infection Not Virologically Suppressed With BulevirtideViral Hepatitis
ACTIVE NOT_RECRUITING150 Analytics
NCT06903338A Study to Evaluate Tobevibart + Elebsiran in Chronic HDV InfectionViral Hepatitis
ACTIVE NOT_RECRUITING124 Analytics
PHASE3ACTIVE NOT_RECRUITING
A Study to Evaluate Tobevibart+Elebsiran in Participants With Chronic HDV Infection Not Virologically Suppressed With Bulevirtide
Viral Hepatitis
NCT07128550150
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PHASE3ACTIVE NOT_RECRUITING
A Study to Evaluate Tobevibart + Elebsiran in Chronic HDV Infection
Viral Hepatitis
NCT06903338124
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Study Endpoints

Primary Endpoints

HDV RNA < Lower Limit of Quantification (LLOQ), Target not detected (TND) at Week 24
Week 24
HDV RNA < Lower Limit of Quantification (LLOQ), Target not detected (TND) 24 weeks after end of treatment.
24 Weeks after End of Treatment
HDV RNA < Lower Limit of Quantification (LLOQ), Target Not Detected (TND) and alanine aminotransferase (ALT) normalization (ALT </= Upper Limit of Normal [ULN]) at Week 48 for Arm 1 vs at Week 12 for Arm 2
Up to 48 weeks
Incidence of Treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) through Week 12
Up to 12 weeks
HDV RNA < Lower Limit of Quantification (LLOQ), Target not detected (TND) at Week 48
Week 48
HDV RNA < Lower Limit of Quantification (LLOQ), Target not detected (TND) 24 weeks after end of treatment
24 Weeks after End of Treatment
Incidence of treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) through Week 48
Week 48
STRIVE and THRIVE: Proportion of Participants Achieving Suppression of HBV DNA (< LLOQ) With HBsAg Loss (< 0.05 IU/mL) at the End of Treatment
Up to 48 weeks
Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Treatment-emergent period, which is up to Week 24 in part A, and up to Week 8 in part B/C/D
Number of Participants With Clinical Laboratory Abnormalities
Up to 280 days post-dose

Secondary Endpoints

Incidence of Treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) through Week 24, Week 48, Week 96, Week 120, Week 144, Week 192, and Week 240
Week 24, Week 48, Week 96, Week 120, Week 144, Week 192, and Week 240
HDV RNA < Lower Limit of Quantification (LLOQ), Target not detected (TND) at Week 48, Week 96, Week 120, Week 144, Week 192 and Week 240
Week 48 , Week 96, Week 120, Week 144, Week 192 and Week 240
Change from baseline in ALT at Week 24, Week 48, Week 96, Week 120, Week 144, Week 192, and Week 240
Week 24, Week 48, Week 96, Week 120, Week 144, Week 192, and Week 240
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Arm 1EXPERIMENTALParticipants will receive treatment with tobevibart + elebsiran up to 240 weeks.
Arm 2EXPERIMENTALParticipants will receive Bulevirtide for 24 weeks and switch to receive tobevibart + elebsiran for additional 216 weeks
Arm 1 (Tobevibart + Elebsiran)EXPERIMENTALParticipants will receive treatment with tobevibart + elebsiran for 240 weeks.
Arm 2 (Tobevibart + Elebsiran)EXPERIMENTALParticipants will receive tobevibart + elebsiran after an observational period for 240 weeks.
STRIVE: Cohort 1a (VIR-3434 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + TDF for 44 weeks total
STRIVE: Cohort 2a (VIR-3434 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + TDF for 44 weeks total
STRIVE: Cohort 3a (VIR-3434 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + TDF for 36 or 40 weeks total
STRIVE: Cohort 4a (VIR-3434 + VIR-2218 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + VIR-2218 + TDF for 20 or 44 weeks total
STRIVE: Cohort 5a (VIR-3434 + VIR-2218 + TDF + PEG-IFNα)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + VIR-2218 +TDF + PEG-IFNα for 48 weeks total
THRIVE: Cohort 1b (VIR-3434 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + TDF for 44 weeks
THRIVE: Cohort 2b (VIR-3434 + VIR-2218 + TDF)EXPERIMENTALParticipants will receive combination therapy with VIR-3434 + VIR-2218 + TDF for 44 weeks total
VIR-3434EXPERIMENTAL -
PlaceboPLACEBO_COMPARATOR -

Interventions

NameTypeDescription
TobevibartDRUGTobevibart administered by subcutaneous injection
ElebsiranDRUGElebsiran administered by subcutaneous injection
BulevirtideDRUGBulevirtide administered by subcutaneous injection
VIR-3434DRUGVIR-3434 given by subcutaneous injection
VIR-2218DRUGVIR-2218 given by subcutaneous injection
TDFDRUGTDF given orally
PEG-IFNαDRUGPEG-IFNα given by subcutaneous injection
PlaceboOTHERSterile normal saline (0.9% NaCl) given by subcutaneous injection or intravenous infusion.
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Eligibility Criteria

Age Range18 Years to 70 Years
SexALL
Healthy VolunteersNo
Study Sites38

Inclusion Criteria: 1. Male or female ages 18 to 70 years at screening 2. HDV RNA ≥ 500 IU/mL at screening 3. Receiving BLV 2 mg SC QD for ≥ 24 weeks at Day 1 4. Noncirrhotic or compensated cirrhotic liver disease at screening 5. On NRTI therapy against HBV for at least 12 weeks prior to day 1 or h...

Countries:AustriaFranceGermanyItalyRomaniaSpainUnited KingdomUnited StatesCanadaGeorgiaMoldovaNew ZealandPakistanUkraineBelgiumBulgariaNetherlandsHong KongSouth KoreaSingapore
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Frequently asked questions about Tobevibart

What is Tobevibart?

Tobevibart is an investigational small molecule being developed by Vir Biotechnology, Inc. for chronic hepatitis B and viral hepatitis, including chronic hepatitis D. It is also known as VIR-3434. It has received FDA Fast Track designation and remains in clinical development.

What does Tobevibart target?

Tobevibart targets hepatitis B surface antigen, or HBsAg. By binding to HBsAg, it is designed to interfere with the surface antigen that is central to hepatitis B and hepatitis D viral activity. This target is the basis for its development in chronic hepatitis B and viral hepatitis.

Who is developing Tobevibart?

Tobevibart is being developed by Vir Biotechnology, Inc., which trades on the Nasdaq under the ticker VIR. The company is the sponsor of the clinical trials evaluating the drug in chronic hepatitis B and viral hepatitis, including chronic hepatitis D.

What phase is Tobevibart in?

Tobevibart is in Phase 1 development. It is an investigational drug and has not been approved by the FDA. The Phase 1 program includes a completed platform study in chronic hepatitis B, while later-phase trials are evaluating it in combination with elebsiran in chronic hepatitis D.

What clinical trials is Tobevibart in?

Tobevibart is being studied in several trials. NCT05612581 is a completed Phase 1 platform study in chronic hepatitis B. NCT07142811 is a Phase 2 study of tobevibart plus elebsiran versus bulevirtide in chronic hepatitis D. NCT07128550 and NCT06903338 are Phase 3 studies of tobevibart plus elebsiran in chronic hepatitis D.

Is Tobevibart the same as VIR-3434?

Yes, Tobevibart is also known as VIR-3434. VIR-3434 is the company code for the same investigational compound. References to either name describe the same drug candidate being developed by Vir Biotechnology for chronic hepatitis B and viral hepatitis.

Other drugs targeting HBsAg

AB-729 ABUS· PHASE2 Brelovitug MIRM· PHASE3

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