X4 Pharmaceuticals, Inc. announced the presentation of additional preliminary data from its ongoing Phase 2 clinical trial evaluating the safety and efficacy of once-daily oral mavorixafor with or without concurrent treatment with injectable granulocyte-colony stimulating factor (G-CSF) in people diagnosed with idiopathic, cyclic, or congenital neutropenia. Julia T. Warren, M.D., Ph.D., a trial investigator and hematologist in the Division of Hematology at the Children?s Hospital of Philadelphia, will be presenting Poster #P1160, December 09, 2023 at the annual meeting of the Annual Society of Hematology (ASH). The poster highlights case studies of the first three participants to complete the 6-month Phase 2 trial, all of whom entered the study on G-CSF therapy.

Overall: Mavorixafor was generally well tolerated when used in combination with G-CSF, with no serious adverse events reported; While 4 infections were reported during the first two months of the trial, no infections were reported during the following 4 months of the trial, despite reductions in G-CSF dosing in two of the three participants; The data continue to support the potential of mavorixafor to raise absolute neutrophil counts (ANC) and enable reduction in G-CSF dosing in patients with chronic neutropenia; The data informed the design of the planned pivotal, global Phase 3 clinical trial of mavorixafor in certain chronic neutropenic disorders, as well as the selection of ANC and infection as primary endpoints; the trial is expected to initiate in the first half of 2024. The poster also highlighted results from a recent qualitative Chronic Neutropenia Patient Voice Survey that confirmed previous market research showing respondents' strong interest in reducing G-CSF dosing and/or reducing injection frequency with the addition of an oral medication such as mavorixafor.