X4 Pharmaceuticals Presents Positive Phase 2 Chronic Neutropenia Trial Data in Poster Presentations at the 30th Annual Congress of the European Hematology Association (EHA)

Core Insights - X4 Pharmaceuticals presented positive data from its Phase 2 trial of mavorixafor for chronic neutropenia at the European Hematology Association Congress, indicating significant increases in circulating neutrophils and the potential to reduce G-CSF usage [1][2][3] Group 1: Clinical Trial Results - The Phase 2 trial was a six-month open-label study involving 23 participants with chronic neutropenia, assessing mavorixafor as a monotherapy and in combination with G-CSF [2][7] - Results showed that mavorixafor monotherapy durably increased mean absolute neutrophil count (ANC) from baseline, with severe chronic neutropenia patients achieving nearly three-fold increases in ANC levels [4][11] - 89% of participants and investigators opted to reduce or discontinue G-CSF while maintaining normal ANC levels, suggesting a potential transition to mavorixafor as an oral treatment option [4][11] Group 2: Ongoing and Future Trials - X4 is conducting a pivotal Phase 3 trial (4WARD) to evaluate mavorixafor's efficacy and safety in chronic neutropenia, aiming to enroll 150 participants and assess annualized infection rates and ANC response over 52 weeks [5][8] - The Phase 3 trial is expected to fully enroll in the third or fourth quarter of 2025, building on the encouraging Phase 2 results [2][5] Group 3: Mechanism and Background - Chronic neutropenia is characterized by low neutrophil levels, increasing infection risk and reducing quality of life; mavorixafor acts as a CXCR4 antagonist, mobilizing neutrophils from the bone marrow [6][9] - The Phase 1b/Phase 2 trial was designed to assess the safety and tolerability of mavorixafor, with the Phase 2 portion focusing on its impact on neutropenia over six months [7][8]