A Phase 1 Study of S-4321

A Phase 1, Randomized, Placebo-Controlled, Double-Blind, Single and Multiple Ascending Dose Trial of S-4321 in Healthy Volunteers

Status

Recruiting

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT06877611

Enrollment

Registered

2025-03-14

Start date

2025-04-03

Completion date

2026-04-30

Last updated

2025-04-15

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy Volunteer

Brief summary

This is the first-in-human study of S-4321 designed to provide safety, tolerability, pharmacokinetic, and pharmacodynamic data in healthy volunteers.

Detailed description

This is a randomized, placebo-controlled, double-blind, study to assess the safety, tolerability, pharmacokinetics, pharmacodynamics of S-4321 administered to healthy adult participants. This study will be conducted in two parts, Part 1 (single ascending dose, SAD) and Part 2 (multiple ascending doses, MAD).

Interventions

DRUGS-4321

S-4321 via subcutaneous or intravenous administration

OTHERPlacebo

Placebo via subcutaneous or intravenous administration.

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

18 Years to 65 Years

Healthy volunteers

Yes

Inclusion criteria

1. Is available for the entire duration of the study and follow up. 2. Is willing and able to comply with all study assessments and adhere to the protocol schedule and restrictions. 3. Voluntarily consents to participation in the trial as documented by signing the study informed consent form (ICF). 4. Has a body mass index (BMI) within 18 to 32 kg/m2, inclusive, and weighs ≥45 kg. 5. Is in good physical and mental health in the opinion of the Investigator or delegate. Major

Exclusion criteria

1. Has a history of severe allergic or anaphylactic reaction as determined by the Investigator or delegate. 2. Is pregnant, nursing, or is planning to become pregnant or breastfeed during the trial. 3. Has a known immunodeficiency disorder. 4. Has a history of malignancy or confirmed cervical dysplasia. 5. Has a history of human immunodeficiency virus (HIV) or positive serology for HIV at Screening. 6. Has positive laboratory evidence for active hepatitis at screening. 7. Has any other condition or prior therapy that, in the opinion of the Investigator or delegate, may potentially compromise the safety or compliance of the participant, or may preclude the participant from successfully completing the study. Other inclusion/exclusion eligibility criteria apply.

Design outcomes

Primary

Measure	Time frame
Number of participants with treatment-related adverse and serious adverse events as assessed by CTCAE v5.0	2 months

Secondary

Measure	Time frame
To assess time to reach maximum serum concentration (tMAX)	2 months
To assess elimination half-life (t1/2)	2 months
To assess area under the serum concentration-time curve from time 0 to t hours (AUC0-t) and to infinity (AUC0-inf)	2 months
To assess clearance (CL)	2 months
To assess the maximum serum concentration (CMAX)	2 months
To assess bioavailability after SC administration (F%)	2 months
To characterize absolute change from baseline of Receptor Occupancy (RO) at multiple timepoints	2 months
Incidence and characterization of anti-drug antibody (ADA)	2 months
To assess volume of distribution (Vz) and steady-state volume of distribution (Vss)	2 months

Countries

Australia

Contacts

Primary ContactSeismic Contact

clinical@seismictx.com1800 244 475

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026