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Treatment for chronic neutropenia using mavorixafor

A Phase 3, Randomized, Double-blind, Placebo-controlled, Multicenter Study of Mavorixafor in Participants With Congenital and Acquired Primary Autoimmune and Idiopathic Chronic Neutropenic Disorders Who Are Experiencing Recurrent and/or Serious Infections

Phase 3 Interventional X4 Pharmaceuticals · NCT06056297

This study is testing if a new drug called mavorixafor can help people with chronic neutropenia, a condition that makes them prone to infections, by boosting their white blood cell levels and lowering infection rates.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment176 (estimated)
Ages12 Years and up
SexAll
SponsorX4 Pharmaceuticals Industry-sponsored
Drugs / interventionschemotherapy
Locations112 sites (Phoenix, Arizona and 111 other locations)
Trial IDNCT06056297 on ClinicalTrials.gov

What this trial studies

This study evaluates the efficacy, safety, and tolerability of mavorixafor in patients with congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorders who are experiencing recurrent or serious infections. Participants will continue their current treatment regimen while receiving either mavorixafor or a placebo. The primary goal is to demonstrate clinical benefit by increasing levels of circulating neutrophils and reducing infection rates.

Who should consider this trial

Good fit: Ideal candidates include individuals diagnosed with congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorders for at least six months.

Not a fit: Patients whose neutropenia is attributable to medications, active infections, or malignancy may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly reduce the frequency and severity of infections in patients with chronic neutropenia.

How similar studies have performed: Other studies have shown promise in treating chronic neutropenia with similar approaches, but the specific use of mavorixafor is novel.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

* Diagnosis of congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorder ≥6 months prior to the screening visit that is not attributable to medications, active or recent infections or malignancy.
* Congenital Neutropenia, including but not limited to these classifications:

  1. Isolated with a permanent (non-cyclic) presentation, for example, elastase, neutrophil expressed (ELANE), colony stimulating factor 3 receptor (CSF3R), C-X-C chemokine receptor 2 (CXCR2), Wiskott-Aldrich syndrome (WAS)
  2. Associated with extra-hematologic manifestations, for example, Barth syndrome, Cohen syndrome, glucose-6-phosphatase catalytic subunit 3 (G6PC3), Kostmann disease
  3. Associated with metabolic disorders, for example, glycogen storage disease 1b (GSD1b)
  4. Shwachman-Diamond syndrome
* Acquired Primary Neutropenia

  1. Chronic idiopathic neutropenia
  2. Primary autoimmune neutropenia. Other chronic neutropenia (CN) disorders that may be eligible for enrollment can be clarified and approved upon discussion with study Medical Monitor.
* Have an ANC \<1000 cells/µL during screening (single ANC value from hematology) and confirmed trough mean ANC (mean value of multiple ANC measurements over 6 hours) at baseline visit, with no clinical evidence of systemic infection.
* Prior history of recurrent and/or serious infections during the 12 months preceding the screening visit (that is, suffering sequelae of chronic neutropenia), as defined by having at least 2 infections in the last 12 months that meet the following criteria:
* Infection requiring the use of antibiotics (intravenous \[IV\]/oral); OR
* Infection requiring a visit to healthcare facility (including but not limited to emergency room visit, urgent care facility, primary care physician's office, or in-patient hospitalization);

AND for all potential participants:

* Infections considered by the Investigator to be likely related to the potential participant's CN disorder.
* Participants who are on G-CSF or other active background therapy must have been receiving these therapies during the previous 12 months while continuing to suffer from infections, be on a stable dose and dosing schedule for ≥4 weeks prior to screening visit and remain on this dose and dosing schedule throughout the study (unless ANC \>10,000 cells/µL for ≥4 weeks).
* Participants must be willing to keep their G-CSF or other background therapy doses/regimens stable (other than for safety reasons) for the duration of the study.

Key Exclusion Criteria:

* A diagnosis of secondary neutropenia including those due to:

  1. Hypersplenism
  2. Infection
  3. Malignancy
  4. Autoimmune disease, for example, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, graft-versus-host disease, thyroid disease
  5. Nutritional deficiency, for example, vitamin B12, folic acid, copper, caloric malnutrition
  6. Drug-induced cause, for example, chemotherapy, clozapine, antiretrovirals, antibiotics, monoclonal antibodies.
* A diagnosis of any of the following:

  1. Aplastic anemia
  2. Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome
  3. Certain CNs, including but not limited to these classifications are excluded:

     1. Isolated with a cyclic presentation, for example, elastase, neutrophil expressed (ELANE)
     2. Associated with immune dysregulation, for example, common variable immunodeficiency (CVID), autoimmune lymphoproliferative syndrome (ALPS), familial hemophagocytic lymphohistiocytosis, Chédiak-Higashi syndrome, GATA-binding protein 2 (GATA2) deficiency syndrome
     3. Associated with bone marrow failure, for example, Fanconi anemia, Diamond-Blackfan anemia
  4. Neutropenia associated with a Duffy-null phenotype (formerly known as benign ethnic neutropenia). However, a participant with an autosomal dominant pathogenic variant in a gene associated with CN on a Duffy-null background may be eligible for inclusion
* A medical or personal condition that may potentially compromise the safety of the participant, may preclude the participant's successful completion of the clinical study, or could, in the opinion of the Investigator or the Medical Monitor, interfere with the objectives of the study.
* Received more than 1 dose of mavorixafor in the past.
* Received C-X-C chemokine receptor 4 (CXCR4) antagonist (other than mavorixafor) in the past 6 months.
* Participants taking pegylated-G-CSF unless they have a diagnosis of congenital neutropenia confirmed at screening.
* Participant is currently taking or has taken other investigational drug \<30 days prior to the screening visit or 5 half-lives, whichever is longer.

Note: Other protocol-defined inclusion and exclusion criteria may apply.

Where this trial is running

Phoenix, Arizona and 111 other locations

+62 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions NeutropeniaMavorixaforChronic neutropeniaChronic idiopathic neutropeniaSevere Congenital NeutropeniaC-X-C chemokine receptor 4Congenital and acquired neutropeniaAutoimmune disease
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.