• 14 May 2020
    X4 Pharmaceuticals Announces Data from Phase 2 Open-Label Extension Trial of Mavorixafor in WHIM Syndrome as Published in EHA Abstract

    X4 Pharmaceuticals, Inc. (Nasdaq: XFOR), a leader in the discovery and development of novel therapies targeting diseases resulting from dysfunction of the CXCR4 pathway, disclosed efficacy and safety data from the Phase 2 open-label extension trial of its lead candidate mavorixafor in patients with WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. These data are included in an abstract published today and selected to be presented as an e-Poster at the 25thEuropean Hematology Association (EHA) Annual Congress, taking place virtually from June 11-14, 2020.

    The original Phase 2 clinical trial was a two-part, open-label, dose-escalation study of mavorixafor in adult patients followed by an open-label extension study to determine the safety, tolerability, and dose selection of mavorixafor in participants with genetically confirmed WHIM syndrome. The extension phase was open to patients who completed at least 24 weeks of the initial dose-escalation study and explored additional endpoints related to infection rates and wart burden, along with long-term safety. The trial results informed the design of the company’s ongoing pivotal Phase 3 clinical trial (4WHIM). Data from the Phase 2 trial also resulted in the receipt of Breakthrough Therapy Designation by the U.S. Food & Drug Administration for mavorixafor for the treatment of WHIM. The company recently updated its estimates regarding WHIM prevalence in the U.S. to 1,300 – 3,700 diagnosed and undiagnosed patients and expects to report top-line data from the global Phase 3 trial in 2022.

    Data from patients treated with 300 mg or 400 mg once-daily doses of mavorixafor for up to 28.6 months will be presented at this year’s EHA Congress. Results summarized in the abstract include:

    • Observed sustained, dose-dependent increases in absolute neutrophil count (ANC) and absolute lymphocyte count (ALC).
    • Long-term hematological improvements correlated with fewer infections and improved cutaneous warts.
      • Clinical yearly infection rates decreased from 4.63 in the 12 months prior to the trial, to 2.41 (a 48% reduction) at 300 mg and 2.14 (a 54% reduction) at 400 mg of mavorixafor.
      • Patients with cutaneous warts on hands and/or feet at baseline demonstrated a greater than 50% reduction in the number of warts at their last dermatological evaluation.
    • Mavorixafor was well tolerated for the extended duration of more than two years without any attributable serious adverse effects.

    These and additional data from the Phase 2 open-label extension study will be presented during a virtual e-Poster presentation:

    Abstract #EP852: Oral CXCR4 Antagonist Mavorixafor Treatment in Patients with WHIM Syndrome: Results of an Open-label Phase 2 Study with Long-term Extension

    Date and Time: Friday, June 12th, 8:30 am CEST / 2:30 am ET
    Session Title: Bone marrow failure syndromes incl. PNH - Clinical