for people ages 12 years and up (full criteria)
at San Diego, California and other locations
study started
completion around



This study has a double-blind, Randomized Placebo-Controlled Period and an Open-Label Period. The primary objective of the Randomized Placebo-Controlled Period is to demonstrate the efficacy of mavorixafor in participants with WHIM syndrome as assessed by increasing levels of circulating neutrophils compared with placebo, and relative to a clinically meaningful threshold. The primary objective of the Open-Label Period is to evaluate the safety and tolerability of mavorixafor in participants with WHIM syndrome. Participants are allowed to continue treatment in the Open-Label Period, if regionally applicable, until mavorixafor becomes commercially available, or until the study is terminated by the Sponsor.

Official Title

A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study of Mavorixafor in Patients With WHIM Syndrome With Open-Label Extension


WHIM Syndrome, Syndrome, Mavorixafor


You can join if…

Open to people ages 12 years and up

for the Randomized Placebo-Controlled Period :

- Have signed the current approved informed consent form. Participants under 18 years of age (in the Netherlands and other applicable regions, participants under 16 years of age) will sign an approved informed assent form and must also have a signed parental/legal guardian consent. - Have a genotype-confirmed mutation of chemokine (C-X-C motif) receptor 4 (CXCR4) consistent with WHIM phenotype. - Agree to use a highly effective form of contraception. - Be willing and able to comply with the protocol. - Have confirmed ANC ≤400 cells/µL during screening, obtained while participant has no clinical evidence of infection. Inclusion Criteria for the Open-Label Period: - Completed the Randomized Period; or - Granted Early Release from the Randomized Period.

You CAN'T join if...

  • Has known systemic hypersensitivity to the mavorixafor drug substance, its inactive ingredients, or the placebo.
  • Is pregnant or breastfeeding.
  • Has any medical or personal condition, which 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.


  • University of California San Diego Health/Rady Children's Hospital
    San Diego California 92123 United States
  • California Dermatology Institute
    Thousand Oaks California 91320 United States


in progress, not accepting new patients
Start Date
Completion Date
X4 Pharmaceuticals
Phase 3 WHIM Syndrome Research Study
Study Type
About 31 people participating
Last Updated