A Dose Determination and Safety Study of X4P-001 (Mavorixafor) in Participants With Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) Syndrome

Study Overview
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Brief Summary
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This is a Phase 2 study with an initial 24-week Treatment Period and an Extension Phase. The primary objectives of this Phase 2 study are to determine the safety, tolerability, and dose selection of mavorixafor in participants with WHIM syndrome. Participants are allowed to continue treatment in an Extension Phase, if regionally applicable, until it becomes commercially available or until the study is terminated by the Sponsor.

Official Title
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A Phase 2, Open-Label, Multi-Center Trial of Mavorixafor in Patients With WHIM Syndrome

Conditions
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WHIM Syndrome

Intervention / Treatment
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* Drug: X4P-001


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants with a clinical diagnosis of WHIM syndrome must meet all of the following criteria to be eligible for study participation: Be at least 18 years of age. Has signed the current approved informed consent form. Has a genotype-confirmed mutation of chemokine receptor type 4 (CXCR4) consistent with WHIM syndrome. Agree to use effective contraception. Be willing and able to comply with this protocol. Has confirmed ANC less than or equal to (≤) 400/µL or ALC ≤650/µL or both. Exclusion Criteria: Participants with any of the following will be excluded from participation in the study: Has known systemic hypersensitivity to the mavorixafor drug substance or its inactive ingredients. Is pregnant or nursing. Has a known history of a positive serology or viral load for human immunodeficiency virus (HIV) or a known history of acquired immunodeficiency syndrome (AIDS). Has, at Screening, laboratory tests meeting one or more of the following criteria: A positive antibody test for hepatitis C virus (HCV), unless documented to have no detectable viral load on 2 independent samples. A positive test for hepatitis B surface antigen (HBsAg). Has any medical or personal condition that, in the opinion of the Investigator, may potentially compromise the safety or compliance of the participant, or may preclude the participant's successful completion of the clinical study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: X4P-001<br>Initial Treatment Phase: Participants will initiate treatment with mavorixafor at 50 milligrams (mg) once daily (QD) orally or a higher dose, with potential escalation based on area under the curve for absolute neutrophil count and absolute leukocyte count (AUCANC/ALC) values to a maximum total daily dose of 400 mg. Participants are expected to receive treatment for 24 weeks in the initial Treatment Period or until development of a treatment-limiting toxicity (TLT). Extension Phase: All participants will receive mavorixafor; the dose will not exceed 400 mg. In the Extension Phase, treatment may continue until mavorixafor becomes available via an alternative mechanism (for example, drug is commercially available, an expanded access program, etc.) or until the study is terminated by the sponsor. | Drug: X4P-001<br>* Mavorixafor will be provided as either 25 mg or 100 mg capsules.<br>* Other names: AMD11070, Mavorixafor;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean AUCANC and/or AUCALC |  | Time 0 (-15 minutes [min] pre-dose), 30, 60, and 90 min (each ± 5 min) and 2, 3, 4, 8, 12, 16, and 24 hours (each ±15 min) at Weeks 5, 13, and 21 |