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

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

Study Overview

• Status: Recruiting
• Conditions: Healthy Volunteer
• Intervention / Treatment: Other: Placebo; Drug: S-4321

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).

• Study Type: Interventional
• Enrollment (Estimated): 96
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Seismic Contact; Phone Number: 1800 244 475; Email: clinical@seismictx.com

Study Locations

• Australia
  • Victoria
    • Bayswater, Victoria, Australia
      • Recruiting
      • Veritus Research
      • Contact: Veritus Contact; Phone Number: +61 3 8736 1750; Email: info@veritusresearch.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: S-4321 Part 1: Single ascending dose (SAD) cohorts	Other: Placebo; Placebo via subcutaneous or intravenous administration.; Drug: S-4321; S-4321 via subcutaneous or intravenous administration
Experimental: S-4321 Part 2: Multiple ascending dose (MAD) cohorts	Other: Placebo; Placebo via subcutaneous or intravenous administration.; Drug: S-4321; S-4321 via subcutaneous or intravenous administration

What is the study measuring?

Primary Outcome Measures

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

Secondary Outcome Measures

Outcome Measure	Time Frame
To assess the maximum serum concentration (CMAX)	2 months
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 volume of distribution (Vz) and steady-state volume of distribution (Vss)	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

Collaborators and Investigators

• Sponsor: Seismic Therapeutic AU Pty Ltd
• Collaborators: Avance Clinical Pty Ltd.

Study record dates

Study Major Dates

• Study Start (Actual): April 3, 2025
• Primary Completion (Estimated): April 1, 2026
• Study Completion (Estimated): April 1, 2026

Study Registration Dates

• First Submitted: March 10, 2025
• First Submitted That Met QC Criteria: March 10, 2025
• First Posted (Actual): March 14, 2025

Study Record Updates

• Last Update Posted (Actual): April 15, 2025
• Last Update Submitted That Met QC Criteria: April 10, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: S-4321-101

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Our IPD sharing plan is not yet developed. We will consider data sharing at a later date.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No