Clinical Trial Information


X4 Pharmaceutical’s (Cambridge, MA) Phase 3 WHIM trial is open now for enrollment, entitled “A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial of mavorixafor (X4P-001) in Patients with WHIM Syndrome with Open-Label Extension

WHIM (Warts, Hypogammaglobulinemia, Infections and Myelokathexis) is a rare autosomal dominant primary immunodeficiency disease caused by gain-of-function mutations in the chemokine receptor CXCR4.  CXCR4 mutations induce increased leukocyte homing and retention in the bone marrow resulting in severe chronic neutropenia and lymphopenia.

X4 Pharmaceuticals is planning to sponsor a 52-week global Phase 3 study to evaluate the safety and efficacy of mavorixafor, a once-daily oral CXCR4 antagonist, in genetically confirmed WHIM patients who are aged 12 years or older.  Mavorixafor is a first-in-class, oral, small molecule antagonist of the CXCR4 chemokine receptor that has demonstrated a favorable safety profile and dose-dependent increases in ANC and ALC in a Phase 2 study. Trial subjects will participate in a one-year trial with an opportunity to continue in the subsequent open label extension.  Travel support to study sites will be provided.

To support confirming the diagnosis of WHIM, X4 Pharmaceuticals will offer genetic testing at no charge to patients meeting eligibility criteria suggestive for the disease.  For information and support for genetic confirmation of your patients with suspected WHIM, please contact This email address is being protected from spambots. You need JavaScript enabled to view it.


Phase 1b Clinical Trial for the Treatment of Severe Congenital and Chronic Idiopathic Neutropenia

X4 Pharmaceuticals, Inc (Cambridge, MA), a clinical-stage biopharmaceutical company focused on the development of novel therapeutics for the treatment of rare diseases, announced the initiation of a Phase 1b open-label, multicenter clinical trial titled: A Study of Mavorixafor in Participants with Severe Congenital. Neutropenia and Chronic Neutropenia Disorders. Visit their web for more information:

The Phase 1b trial is a 14-day, proof-of-concept trial designed to assess the safety and tolerability of daily, oral mavorixafor – an investigational therapy – in up to 45 participants with Severe Congenital Neutropenia (SCN) disorders or Chronic Idiopathic Neutropenia (CIN). In addition, the trial will evaluate the neutrophil response, of mavorixafor, as an independent agent or in combination with granulocyte-colony stimulating factor (G-CSF). SCN are rare disorders; genetic testing can help to confirm the diagnosis and enhance patient access to appropriate care. Through its collaborative PATH4WARD program, X4 provides genetic testing at no cost to patients with severe neutropenia. This initiative provides greater access to faster and earlier diagnosis for individuals who may carry a genetic mutation known to be associated with SCN.

For inquiries about the clinical trial and/or PATH4WARD genetic testing program, please contact X4 pharmaceuticals at This email address is being protected from spambots. You need JavaScript enabled to view it..