A Phase 3 interventional study of Mavorixafor and Placebo in Neutropenia, sponsored by X4 Pharmaceuticals. Recruiting at 114 sites in 25 countries. Open to participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-08-06.
Sponsored by X4 Pharmaceuticals · Phase 3, Interventional, and Treatment
The purpose of this study is to demonstrate the efficacy and evaluate the safety and tolerability of mavorixafor in participants with congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorders who are experiencing recurrent and/or serious infections as assessed by demonstrating its clinical benefit and increasing levels of circulating neutrophils.
All participants will continue their pre-study background therapy, defined as the participant's current treatment regimen. Options include, but are not limited to, granulocyte-colony stimulating factor (G-CSF), immunoglobulin replacement therapy, prophylactic antibiotics, or "watchful waiting".
Key Inclusion Criteria:
Congenital Neutropenia, including but not limited to these classifications:
Acquired Primary Neutropenia
AND for all potential participants:
Key Exclusion Criteria:
A diagnosis of secondary neutropenia including those due to:
A diagnosis of any of the following:
Certain CNs, including but not limited to these classifications are excluded:
Note: Other protocol-defined inclusion and exclusion criteria may apply.
Participants will receive mavorixafor orally once daily starting from Day 1 through Week 52.
Drug: Mavorixafor
Participants will receive placebo to match mavorixafor orally once daily starting from Day 1 through Week 52.
Drug: Placebo
Mavorixafor will be administered per schedule specified in the arm description.
Also known as: X4P-001
Placebo will be administered per schedule specified in the arm description.
Co-primary Endpoint: Annualized Infection Rate Based on Infections Adjudicated by Blinded Infection Adjudication Committee (BIAC) During the Treatment Period
Time frame: Up to 52 Weeks
Co-primary Endpoint: Number of Participants Meeting the Definition of a Positive Absolute Neutrophil Count (ANC) Response
Positive ANC response: Increase of ANC \>500 cells/microliter (µL) from baseline.
Time frame: Up to 52 weeks
Infection Severity Based on Common Terminology Criteria for Adverse Events (CTCAE) Adjudicated by a BIAC During the Treatment Period
Time frame: Up to 52 Weeks
Infection Duration Based on Duration of Infections Adjudicated by a BIAC During the Treatment Period in Those Participants who Developed Infections
Time frame: Up to 52 Weeks
Antibiotic Use Due to Infection, Characterized by the Frequency of Antibiotic Use During the Treatment Period
Time frame: Up to 52 Weeks
Oral Ulcers, as Assessed by Presence or Absence of Ulcers During the Treatment Period
Time frame: Up to 52 Weeks
Change From Baseline in Patient Reported Outcomes Measurement Information System Short Form (PROMIS SF) Fatigue Questionnaire Total Score
Time frame: Baseline, Week 52
Showing the first 100 of 114 sites across 25 countries.
Plan to share: No
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X4 Pharmaceuticals