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

Brief Title

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

Official Title

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

Brief Summary

      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.

Study Phase

Phase 2

Study Type


Primary Outcome



WHIM Syndrome



Study Arms / Comparison Groups

Description:  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.


* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.

Recruitment Information

Recruitment Status


Estimated Enrollment


Start Date

December 2016

Completion Date

December 2022

Primary Completion Date

December 2022

Eligibility Criteria

        Inclusion Criteria:

        Participants with a clinical diagnosis of WHIM syndrome must meet all of the following
        criteria to be eligible for study participation:

          1. Be at least 18 years of age.

          2. Has signed the current approved informed consent form.

          3. Has a genotype-confirmed mutation of chemokine receptor type 4 (CXCR4) consistent with
             WHIM syndrome.

          4. Agree to use effective contraception.

          5. Be willing and able to comply with this protocol.

          6. 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:

          1. Has known systemic hypersensitivity to the mavorixafor drug substance or its inactive

          2. Is pregnant or nursing.

          3. 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).

          4. 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).

          5. 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.




18 Years - N/A

Accepts Healthy Volunteers



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Location Countries


Location Countries


Administrative Informations



Organization ID


Secondary IDs


Responsible Party


Study Sponsor

X4 Pharmaceuticals

Study Sponsor

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Verification Date

August 2021