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GS-4321

Phase 1

Chronic Hepatitis Delta | Small molecule | Infectious Disease |Gilead Sciences, Inc.|Last Updated: Aug 27, 2026

Success Probability

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Market & Valuation

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Trial Design

Double-BlindPLACEBO_CONTROLLED
Total Trials1
Total Enrollment200

FDA Designations

No designations recorded

Clinical trial landscape

GS-4321 · 1 trial · 1 indication

Phase 1 1
NCT07096193Study of GS-4321 in Healthy Participants and Participants With Chronic Hepatitis Delta VirusChronic Hepatitis Delta
RECRUITING200 Analytics
PHASE1RECRUITING
Study of GS-4321 in Healthy Participants and Participants With Chronic Hepatitis Delta Virus
Chronic Hepatitis DeltaUnlock trial analytics

Study Endpoints

Primary Endpoints

Phase 1 and 2: Percentage of Participants With Treatment-emergent Adverse Events
Phase 1: First dose up to 44 weeks; Phase 2: First dose up to 96 Weeks plus 48 weeks of posttreatment follow-up
Phase 1 and 2: Percentage of Participants With Treatment-emergent Serious Adverse Events
Phase 1: First dose up to 44 weeks; Phase 2: First dose up to 96 Weeks plus 48 weeks of posttreatment follow-up
Phase 1 and 2: Percentage of Participants Experiencing Treatment-emergent Clinical Laboratory Abnormalities
Phase 1: First dose up to 44 weeks; Phase 2: First dose up to 96 Weeks plus 48 weeks of posttreatment follow-up
Phase 1: Serum Pharmacokinetic (PK) parameter; AUC of GS-4321
First dose up to 24 Weeks

AUC is defined as the area under the concentration versus time curve

Phase 1: Serum PK Parameter: Cmax
First dose up to 24 Weeks

Cmax is defined as the maximum observed concentration of drug.

Phase 1: Serum PK Parameter: Tmax
First dose up to 24 Weeks

Tmax is defined as the time (observed time point) of Cmax.

Phase 1: Serum PK Parameter: t1/2
First dose up to 24 Weeks
Phase 2: Proportion of Participants with Combined Response
Up to 96 Weeks

Combined Response is defined as undetectable hepatitis delta virus (HDV) RNA or ≥ 2 log10 decrease in HDV RNA from baseline and normal alanine aminotransferase (ALT) normalization (ALT \< upper limit of normal (ULN) at week 24).

Secondary Endpoints

Phase 1: Proportion of Participants who Develop Antidrug Antibody (ADAs) After Administration of a Single Dose of GS-4321 and ADA Titer Characterization
First dose up to 24 Weeks
Phase 2: Serum PK Parameters AUC of GS-4321
Up to 96 weeks
Phase 2: Serum PK Parameters Cmax of GS-4321
Up to 96 Weeks
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingDOUBLE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Phase 1: GS-4321EXPERIMENTALParticipants will receive single escalating doses of GS-4321.
Phase 1: PlaceboPLACEBO_COMPARATORParticipants will receive placebo to match the single escalating doses of GS-4321
Phase 2: GS-4321EXPERIMENTALParticipants will receive multiple escalating doses of GS-4321 up to 96 weeks.

Interventions

NameTypeDescription
GS-4321DRUGAdministered subcutaneous (SC) or intravenously IV
GS-4321 PlaceboDRUGAdministered SC
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Eligibility Criteria

Age Range18 Years to 69 Years
SexALL
Healthy VolunteersYes
Study Sites28

Key Inclusion Criteria: Part A: * Participants assigned male or female at birth who are of childbearing potential and engage in heterosexual intercourse must agree to use protocol-specified method(s) of contraception. * Have a body mass index (BMI) of ≤ 30.0 kg/m2 at screening and at admission. P...

Countries:United StatesBulgariaGermanyItalyMoldovaRomaniaSouth KoreaTaiwanTurkey (Türkiye)
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Recent Changes (Last 90 Days)

LOWAug 27, 2026NCT07096193lastUpdatePostDate: changed
LOWAug 27, 2026NCT07096193lastUpdatePostDate: changed
LOWJul 30, 2026NCT07096193lastUpdatePostDate: changed
LOWJul 30, 2026NCT07096193lastUpdatePostDate: changed
MEDIUMJun 11, 2026NCT07096193Enrollment: 107 → 200
MEDIUMJun 11, 2026NCT07096193Enrollment: 107 → 200

Frequently asked questions about GS-4321

What is GS-4321 used for?

GS-4321 is an investigational small molecule being developed for the treatment of chronic hepatitis delta, a serious liver infection caused by the hepatitis D virus. It is currently in Phase 1 clinical development and has not been approved by regulatory authorities.

Who makes GS-4321?

GS-4321 is being developed by Gilead Sciences, Inc., a biopharmaceutical company traded on the NASDAQ under the ticker symbol GILD. The company is conducting clinical trials to evaluate the safety and efficacy of this investigational drug.

What phase is GS-4321 in?

GS-4321 is in Phase 1 clinical development. It is an investigational drug, meaning it has not been approved by the FDA or other regulatory agencies. The ongoing Phase 1 trial is currently recruiting participants to assess the drug's safety and tolerability.

What clinical trials is GS-4321 in?

GS-4321 is being studied in a Phase 1 clinical trial with the identifier NCT07096193. This trial is titled 'Study of GS-4321 in Healthy Participants and Participants With Chronic Hepatitis Delta Virus' and is currently recruiting up to 200 participants across multiple countries.

Is GS-4321 the same as any other drug?

GS-4321 is a unique investigational compound and is not known to be the same as any other marketed drug. It is a small molecule being developed specifically for chronic hepatitis delta, and no alternative names have been associated with this asset in its development program.