A Phase 1 Open-label Study to Evaluate Safety in Healthy Participants and Participants With Idiopathic Inflammatory Myopathy (IIM)
A Phase 1, First-in-Human, Open-Label, Dose-Escalation Study to Evaluate the Safety and Tolerability, Pharmacokinetics, and Pharmacodynamics of XmAb657 in Healthy Participants and in Participants With Idiopathic Inflammatory Myopathy
1 other identifier
interventional
27
1 country
1
Brief Summary
The purpose of this study is to determine the safety and tolerability of XmAb657 in healthy participants and participants with IIM. Participants will be given XmAb657 subcutaneously (SC) by injection under the skin.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P25-P50 for phase_1 healthy
Started Feb 2026
Longer than P75 for phase_1 healthy
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
December 3, 2025
CompletedFirst Posted
Study publicly available on registry
December 16, 2025
CompletedStudy Start
First participant enrolled
February 1, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
February 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
February 1, 2027
December 16, 2025
December 1, 2025
1 year
December 3, 2025
December 15, 2025
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Percentage of participants with treatment emergent adverse events (TEAEs) and serious adverse events (SAEs)
Through Week 24
Secondary Outcomes (1)
Serum concentration of XmAb657
Through Week 24
Study Arms (1)
Dose Escalation
EXPERIMENTALXmAb657 administered SC
Interventions
Eligibility Criteria
You may qualify if:
- Healthy participants - Adult participants in good health
- Idiopathic inflammatory myopathy participants - Adult participants that meet the 2017 European Alliance of Association Rheumatology (EULAR)/American College of Rheumatology (ACR) classification of Idiopathic inflammatory myopathy
- Idiopathic inflammatory myopathy participants - Stable doses of Idiopathic inflammatory myopathy medications prior to screening
- All participants - Use of highly effective methods of contraception
You may not qualify if:
- Major surgery within 12 weeks prior to screening or planned within 12 months after dosing
- Recurrent infections or active clinically significant infection
- Active or untreated latent tuberculosis
- Cancer or history of cancer or lymphoproliferative disease within the previous 5 years
- Uncontrolled cardiovascular, pulmonary, renal, hepatic, endocrine, or gastrointestinal disease
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Xencor, Inc.lead
Study Sites (1)
Xencor Investigative Site
Melbourne, Australia
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- STUDY DIRECTOR
Mark Osterman, MD, MSCE
Xencor, Inc.
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 1
- Allocation
- NA
- Masking
- NONE
- Purpose
- TREATMENT
- Intervention Model
- SINGLE GROUP
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
December 3, 2025
First Posted
December 16, 2025
Study Start
February 1, 2026
Primary Completion (Estimated)
February 1, 2027
Study Completion (Estimated)
February 1, 2027
Last Updated
December 16, 2025
Record last verified: 2025-12