A Single- and Multiple-Ascending Dose Study of SRK-439 in Healthy Adults

A Phase 1 Single- and Multiple-Ascending Dose Study to Assess the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of SRK-439 in Healthy Adults

A phase 1 study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of SRK-439 in healthy adults

Study Overview

• Status: Recruiting
• Conditions: Healthy
• Intervention / Treatment: Drug: Placebo; Drug: SRK-439; Drug: SRK-439

• Study Type: Interventional
• Enrollment (Estimated): 76
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Scholar Rock, Inc. Clinical Trials Administration; Phone Number: 857-259-3860; Email: MedicalInformation@scholarrock.com

Study Locations

• United States
  • Ohio
    • Cincinnati, Ohio, United States, 45227
      • Recruiting
      • Medpace CPU

Participation Criteria

Eligibility Criteria

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

Description

Key Inclusion Criteria:

1. Male or female participants, ≥18 to ≤55 years of age, at the time of informed consent
2. BMI of ≥18 kg/m2 to ≤35 kg/m2 (inclusive) at screening

Exclusion Criteria:

1. Previous treatment with SRK-439 or apitegromab, or with other anti-myostatin therapies, including ACTR antagonists.
2. History of immunosuppressive, chemotherapeutic, or radiation treatment within 12 months prior to screening.
3. Current or prior use of anabolic steroids, growth hormones, or other substances with known effects on muscle.
4. Use of therapies with potentially significant muscle effects (eg, insulin-like growth factor, systemic beta-agonist, neurotoxins, or muscle relaxants or muscle-enhancing supplements) in any form within 3 months prior to screening or during the study.
5. Any history of exposure to a mAb or Fc domain-bearing recombinant protein within 5 years prior to screening with any prior history of hypersensitivity reactions from exposure
6. Treatment with other investigational drugs or devices in a clinical study or exposure to a biologic therapeutic within 3 months or 5 half-lives, whichever is longer, prior to screening.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part A; Participants will be treated with a single dose of SRK-439 or matching placebo.	Drug: Placebo; Matching placebo to SRK-439, subcutaneous administration; Drug: SRK-439; Single ascending dose, subcutaneous administration; Drug: SRK-439; Multiple ascending dose, subcutaneous administration
Experimental: Part B; Participants will be treated with multiple doses of SRK-439 or matching placebo.	Drug: Placebo; Matching placebo to SRK-439, subcutaneous administration; Drug: SRK-439; Single ascending dose, subcutaneous administration; Drug: SRK-439; Multiple ascending dose, subcutaneous administration

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	• Incidence of AEs	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	• Incidence of SAEs	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in clinical safety laboratory tests (serum chemistry)	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in clinical safety laboratory tests (hematology)	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in clinical safety laboratory tests (urinalysis)	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in clinical safety laboratory tests (coagulation assessments)	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in vital signs (heart rate) measured in bpm	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in vital signs (blood pressure) measured in mmHg	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in vital signs (respiratory rate) measured in rpm	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in vital signs (body temperature) measured in Celsius	Up to 32 weeks
Evaluate the safety and tolerability of single and multiple SRK-439 SC dose administration in healthy adult participants	Changes from baseline in ECG measurements	Up to 32 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluate the PK of single and multiple SRK-439 SC dose administration in healthy adult participants	• Maximum observed serum concentration [Cmax]	Up to 32 weeks
Evaluate the PK of single and multiple SRK-439 SC dose administration in healthy adult participants	• Time to maximum observed concentration in serum [Tmax]	Up to 32 weeks
Evaluate the PK of single and multiple SRK-439 SC dose administration in healthy adult participants	• Area under the serum concentration-time curve [AUC]	Up to 32 weeks
Evaluate the PK of single and multiple SRK-439 SC dose administration in healthy adult participants	• Terminal elimination half-life in serum [t1/2]	Up to 32 weeks
Evaluate the PD of single and multiple SRK-439 SC dose administration in healthy adult participants	Serum concentrations of total latent myostatin and changes over time	Up to 32 weeks
Evaluate the immunogenicity of single and multiple SRK-439 SC dose administration in healthy adult participants	Incidence of ADAs against SRK-439 in serum	Up to 32 weeks

Collaborators and Investigators

• Sponsor: Scholar Rock, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): November 21, 2025
• Primary Completion (Estimated): December 17, 2026
• Study Completion (Estimated): June 9, 2027

Study Registration Dates

• First Submitted: February 11, 2026
• First Submitted That Met QC Criteria: February 24, 2026
• First Posted (Actual): March 2, 2026

Study Record Updates

• Last Update Posted (Actual): March 2, 2026
• Last Update Submitted That Met QC Criteria: February 24, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: SRK-439-001

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No