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NeutropeniaPhase 1/2NCT04154488

A Study of Mavorixafor in Participants With Congenital Neutropenia and Chronic Idiopathic Neutropenia Disorders

A Phase 1/2 study testing Mavorixafor in people with Neutropenia, run by X4 Pharmaceuticals at 7 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This is a 2-part study of mavorixafor in participants diagnosed with chronic neutropenia. The main goal of Part 1 (Phase 1b) is to help researchers learn more about how the investigational medicine, mavorixafor, impacts people living with chronic neutropenia (including congenital, idiopathic, and cyclic). Read more about this study

Who is it for?
Ages 12 years and older
Conditions the study is for
Neutropenia
What is being tested?
Mavorixafor
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
32 participants
Where
7 sitesUnited States
Study dates
16 Oct 2021to 27 Aug 2024
Phase
Phase 1/2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 12 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • For all participants (Parts 1 and 2):
  • Sign the informed consent form (ICF) and be willing and able to comply with the protocol.
  • Weigh ≥15 kg
  • Agree to use a highly effective form of contraception if sexually active.
  • Participants may be eligible for the study whether they are on or off granulocyte-colony stimulating factor (G-CSF) treatment.
  • Note: Participants who are on G-CSF must be on a stable dose for ≥14 days prior to the Baseline visit and should not have an ANC ≥10,000 cells/μL.
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  • Note: Participants who are not on G-CSF must be off for ≥14 days prior to the Baseline visit and have an ANC ≤1000 cells/µL at the Screening visit.
  • Note: Participants with Shwachman-Diamond syndrome, Cohensyndrome, and warts, hypogammaglobulinemia, infections and myelokathexis syndrome are eligible. Other types of chronic neutropenic disorders may also be eligible for enrollment upon discussion and approval with Sponsor and Study Medical Monitor.
  • Have been diagnosed with chronic neutropenia for ≥6 months prior to the Screening visit that is not attributable to medications, active or recent (≤3 months) infections, or malignant cause.
  • Part 2 only:
  • Participants enrolled in the study before implementation of Protocol Version 8.0 must have completed Part 1 and exhibited a positive response to treatment.
  • Participant has a history of symptomatic chronic neutropenia confirmed by the Investigator.

Who cannot join

  • Known systemic hypersensitivity to the mavorixafor drug substance or its inactive ingredients.
  • Is pregnant, breastfeeding, or plans to become pregnant over the next 8 months.
  • Known history of a positive serology or viral load for human immunodeficiency virus (HIV) or a known history of acquired immune deficiency syndrome.
  • Known active SARS-CoV-2 virus (COVID-19) infection or a positive test within the local accepted clinical and governmental guidelines for a communicable window.
  • At the Screening Visit, has laboratory test results meeting one or more of the following criteria:
  • Positive hepatitis C virus (HCV) antibodies with confirmation by HCV-ribonucleic acid polymerase chain reaction reflex testing.
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  • Positive hepatitis B surface antigen (hBsAg) or hepatitis B core antibody (hBcAb).
  • Note: If a participant tests negative for hBsAg but positive for hBcAb, the participant would be considered eligible if the participant tests positive for antibody to hBsAg reflex testing.
  • At the Screening visit, has laboratory test results meeting one or more of the following criteria:
  • Hemoglobin <9.0 grams/deciliter (g/dL)
  • Platelets <30,000/μL
  • Estimated glomerular filtration rate (eGFR) ≤60 mL/minute/1.73 meter (m)^2, as estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation
  • Serum aspartate transaminase >2.5 x upper limit of normal (ULN)
  • Serum alanine transaminase >2.5 x ULN
  • Total bilirubin >1.5 x ULN (unless due to Gilbert's syndrome, in which case total bilirubin greater than or equal to (≥) 3.0 x ULN and direct bilirubin >1.5 x ULN)
  • ≤14 days before Day 1, received any of the following treatments:
  • Systemic glucocorticoids (>5 mg prednisone equivalent per day).
  • Medication prohibited based on cytochrome P450 (CYP)2D6 potential for interaction.
  • Is taking a medication which is a strong inhibitor of CYP3A4, unless the Investigator and Medical Monitor conclude that the medication must be used during the study and is permissible with modification of mavorixafor dose.
  • Has an infection requiring use of systemic antibiotics ≤4 weeks before the Baseline visit.
  • Has a medical or personal condition that may potentially compromise the safety or compliance of the participant, or may preclude the participant's successful completion of the clinical study or that in the opinion of the Investigator or the Sponsor could interfere with the objectives of the study.
  • Has had major surgery ≤4 weeks before the Baseline visit.
  • Inability to ingest mavorixafor capsules.
  • Has an active malignancy or history of (≤5 years prior to enrollment) in the study of solid, metastatic, or hematologic malignancy. Exception: basal cell carcinoma in situ of the skin that has been adequately treated.
  • Diagnosed or has suspected congenital long QT syndrome. Any history of clinically significant ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or torsades de pointes); any history of arrhythmia will be discussed with the sponsor's medical monitor before participant's entry into the study.
  • Prolonged corrected QT interval using Fridericia's formula at the Screening visit electrocardiogram (ECG) (>450 milliseconds [ms])

Trial locations and contacts

7 sites in 1 country.

7 sites in 1 country

United States7 sites

  • University of Michigan

    Ann Arbor, Michigan, 48109

  • University of Texas, Southwestern

    Dallas, Texas, 75235

  • University of Iowa Hospital and Clinics

    Iowa City, Iowa, 52242

  • Children's Hospital of Philadelphia

    Philadelphia, Pennsylvania, 19104

  • University of Washington

    Seattle, Washington, 98195

  • Washington University School of Medicine

    St Louis, Missouri, 63110

  • USF Health Department of Pediatrics

    St. Petersburg, Florida, 33701

Other trials in United States

About this study

Official title: A Phase 1b/2, Open-Label, Multicenter Study of Mavorixafor in Patients With Congenital Neutropenia and Chronic Neutropenia Disorders

This is a 2-part study of mavorixafor in participants diagnosed with chronic neutropenia. The main goal of Part 1 (Phase 1b) is to help researchers learn more about how the investigational medicine, mavorixafor, impacts people living with chronic neutropenia (including congenital, idiopathic, and cyclic). In Part 2 (Phase 2), the safety and tolerability of chronic dosing of mavorixafor will be evaluated in a larger participant population and the impact of 6-month chronic dosing of mavorixafor on participant neutropenia.

Read the detailed description

Part 1: Participants will receive one oral dose of mavorixafor and be monitored for 8 hours to see if neutrophil cell counts increase. Participants screened after implementation of Protocol Version 8.0, do not need to enter Part 1 and can start with the Part 2 Screening visit (Day -28 to Day -1).

Part 2: For participants enrolled in the study before implementation of Protocol Version 8.0, Part 2 will include those who completed Part 1 and exhibited a response to treatment. Eligible participants from Part 1 enrolled in the study before implementation of Protocol Version 8.0, can directly roll-over to the Baseline (Day -3 to Day -1) visit in Part 2. Participants will receive once daily oral dosing of mavorixafor for 6 months and be monitored throughout to see if neutrophil cell counts increase.

Study visits can be conducted at-home or at one of many study clinic locations, depending on the participant's preference.

Conditions
Neutropenia
Being tested
Mavorixafor
Keywords
Chronic congenital neutropenia, Chronic idiopathic neutropenia, SCN, CIN, CXCR4, Mavorixafor, Neutropenia glycogen storage disease type 1b, GSD1b, G6PC3, SLC37A4, GATA2
Medical subject headings
Neutropenia, Glycogen Storage Disease Id

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • MavorixaforDrug

    Also called X4P-001

    Mavorixafor capsules will be administered per dose and schedule specified in the arm.

Study groups in NCT04154488
Study groupRoleWhat they receive
MavorixaforExperimentalPart 1: Adult participants and adolescent participants who weigh more than 50 kilograms (kg) will receive mavorixafor 400 milligrams (mg) (4 capsules of 100 mg each), orally once on Day 1. Adolescents weighing less than or equal to 50 kg will receive mavorixafor 200 mg (2 capsules of 100 mg each), orally once on Day 1. Part 2: Eligible participants from Part 1 will receive once daily dosing of mavorixafor for 6 months.
Receives: Drug: Mavorixafor

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of Participants With Treatment-Emergent Adverse Events (TEAEs) After a Single Dose of Mavorixafor

    Measured: Baseline through Day 1 and 7 days follow-up

  2. Number of Participants With Treatment-Emergent Adverse Events (TEAEs) After Multiple Doses of Mavorixafor

    Measured: Baseline through Month 6 and 30 days follow-up

  3. Change From Baseline in Absolute Neutrophil Count (ANC) to 8 hours Post-dose On Day 1

    Measured: Baseline, 8 hours Post-dose On Day 1

  4. Change From Baseline in ANC to Month 6

    Measured: Baseline, Month 6

Secondary outcomes (9)

  1. Serum Concentration of Mavorixafor in Relation to ANC and Area Under the Curve (AUC) for ANC (AUCANC)

    Measured: 0 (pre-dose), 60 minutes and 2, 3, 4, 6, and 8 hours post-dose on Day 1

  2. Serum Concentrations of Mavorixafor

    Measured: 0 (pre-dose) up to Month 6

  3. Change from Baseline in Absolute Lymphocyte Count (ALC)

    Measured: Baseline, Month 6

  4. Change from Baseline in Total White Blood Cells (WBC)

    Measured: Baseline, Month 6

  5. Change from Baseline in Absolute Monocyte (AMC)

    Measured: Baseline, Month 6

  6. AUC of ANC (AUCANC)

    Measured: Baseline up to Month 6

  7. AUC of ALC (AUCALC)

    Measured: Baseline up to Month 6

  8. AUC of AMC (AUCAMC)

    Measured: Baseline up to Month 6

  9. AUC of WBC (AUCWBC)

    Measured: Baseline up to Month 6

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted6 Nov 2019
  2. Study start16 Oct 2021
  3. Primary completion27 Aug 2024
  4. Study completion27 Aug 2024

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
32 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04154488
Sponsor's protocol ID
X4P-001-104
Status last verified
Aug 2025
First submitted
4 Nov 2019
Last updated
6 Aug 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing Mavorixafor in people with Neutropenia, run by X4 Pharmaceuticals at 7 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 12 inclusion and 26 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 6 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 7 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants With Treatment-Emergent Adverse Events (TEAEs) After a Single Dose of Mavorixafor (time frame: Baseline through Day 1 and 7 days follow-up). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04154488.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Aug 2025.

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