Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not recruitingRare disease

Study on Mavorixafor for Treating WHIM Syndrome in Patients

Verified siteInvestigational
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying WHIM Syndrome, a rare genetic disorder that affects the immune system. The study is testing a treatment called Mavorixafor, which is taken as a capsule. The purpose of the study is to evaluate how effective Mavorixafor is in increasing the levels of certain white blood cells, called neutrophils, in people with WHIM Syndrome. The study also aims to assess the long-term safety and tolerability of the treatment.

The study is divided into two parts. In the first part, participants will be randomly assigned to receive either Mavorixafor or a placebo, which looks like the treatment but does not contain the active ingredient. This part of the study will help determine how well Mavorixafor works compared to the placebo. In the second part, all participants will receive Mavorixafor to further evaluate its safety over a longer period.

Throughout the study, participants will have regular check-ups to monitor their health and the effects of the treatment. This includes blood tests to measure the levels of neutrophils and other white blood cells, as well as assessments of any side effects. The study will help researchers understand if Mavorixafor can be a beneficial treatment for people with WHIM Syndrome.

The research process

The trial runs in 2 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomized placebo-controlled period

    During this period, the effectiveness of mavorixafor is evaluated in patients with WHIM syndrome. The goal is to increase the levels of certain blood cells called neutrophils.

    Participants will receive either mavorixafor or a placebo. The medication is taken orally in the form of a hard capsule.

    The dosage and frequency of administration are determined by the study protocol, and the treatment lasts for 12 months.

    The primary focus is on the time the neutrophil count remains above a specific level, assessed every three months.

  2. Step 2

    Open-label extension period

    Participants who complete the randomized period or are granted early release can enter this phase.

    In this period, all participants receive mavorixafor to evaluate its long-term safety and tolerability.

    The focus is on monitoring any side effects and changes in health through various assessments, including blood tests and physical examinations.

Who can join the trial?

6 criteria

  • Be at least 12 years old.
  • Have signed the current approved Informed Consent Form. If under 18 years old (or under 16 in some regions), a signed informed assent form is needed, along with a signed parental or legal guardian consent.
  • Have a confirmed genetic mutation in the **CXCR4** gene that matches the **WHIM** syndrome characteristics.
  • Agree to use a highly effective form of birth control.
  • Be willing and able to follow the study's rules and procedures.
  • Have a confirmed **ANC** (Absolute Neutrophil Count) of 400 cells per microliter or less during screening, without any signs of infection.

Who cannot join the trial?

7 criteria

  • Participants who do not have a confirmed diagnosis of WHIM Syndrome. WHIM Syndrome is a rare genetic disorder that affects the immune system.
  • Individuals who are not within the specified age range for the study. The study includes certain age groups, so participants must fall within these age categories.
  • Participants who are unable to comply with the study procedures or follow-up requirements. This means they must be able to attend all necessary appointments and follow the study guidelines.
  • Individuals who are currently participating in another clinical trial. Being in another study might interfere with the results of this trial.
  • Participants who have any medical condition that the study doctors believe would make it unsafe for them to participate. This could include other serious health issues that might be affected by the study treatment.
  • Women who are pregnant or breastfeeding. The study may have unknown effects on pregnancy or nursing infants.
  • Individuals who have a known allergy or adverse reaction to the study medication or any of its ingredients. This is to prevent any harmful allergic reactions.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

Mavorixafor is a medication being studied for its effectiveness in treating patients with WHIM syndrome, a rare genetic disorder. The trial aims to see if mavorixafor can increase the levels of certain white blood cells called neutrophils, which are important for fighting infections. The study also looks at the long-term safety and how well patients tolerate the medication.

What is already known about the treatment

Mavorixafor – Mavorixafor is administered orally and is currently being studied in a Phase 3 clinical trial for its effectiveness in treating WHIM Syndrome, a rare immunodeficiency disorder. The medication is designed to increase the levels of circulating neutrophils, which are a type of white blood cell important for fighting infections. Mavorixafor works by inhibiting a specific receptor on the surface of cells, which helps to mobilize neutrophils from the bone marrow into the bloodstream. It is classified as a small molecule antagonist targeting the CXCR4 receptor.

Investigated diseases

WHIM Syndrome – WHIM Syndrome is a rare genetic disorder characterized by a combination of Warts, Hypogammaglobulinemia, Infections, and Myelokathexis. Individuals with this condition often experience recurrent bacterial infections due to low levels of antibodies and white blood cells. The syndrome is named for the symptoms it causes, including persistent skin warts and a reduced ability to fight infections. Myelokathexis refers to the retention of neutrophils in the bone marrow, leading to a shortage of these cells in the bloodstream. This shortage contributes to the increased susceptibility to infections. The progression of WHIM Syndrome can vary, but it typically involves chronic management of symptoms and monitoring for complications.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-518461-10-00Protocol codeX4P-001-103Estimated enrolment14 patientsSponsorX4 Pharmaceuticals Inc.

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.