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GS-4321

Phase 1

Chronic Hepatitis Delta | Small molecule | Infectious Disease |Gilead Sciences, Inc.|Last Updated: Apr 29, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
Double-BlindPLACEBO_CONTROLLEDBiomarker
Total Trials1
Total Enrollment107
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT07096193Study of GS-4321 in Healthy Participants and Participants With Chronic Hepatitis Delta VirusPHASE1 RECRUITING 107 — — Jul 31, 2025Feb 1, 2029Apr 29, 202615 United States, Moldova +3
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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; AUClast of GS-4321
First dose up to 24 Weeks

AUClast is defined as the area under the concentration versus time curve from time zero to the last quantifiable concentration.

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

AUCinf is defined as the area under the concentration versus time curve extrapolated to infinite time.

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 AUCtau 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 — 70 Years
SexALL
Healthy VolunteersYes
Study Sites15

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 StatesMoldovaRomaniaSouth KoreaTaiwan
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT07096193primaryCompletionDate: changed
LOWMay 24, 2026NCT07096193studyFirstPostDate: changed