X4 Pharmaceuticals (XFOR) Study Update summary

Background and Unmet Need in Chronic Neutropenia

• Chronic neutropenia affects about 50,000 patients in the U.S., with over 15,000 experiencing recurrent infections despite current treatments.

• G-CSF is the only approved therapy but is associated with injection discomfort, bone pain, and long-term risks such as myelodysplasia and leukemia.

• There is a strong need for an effective, well-tolerated oral therapy to improve quality of life and reduce infection risk.

Mavorixafor Mechanism and Prior Data

• Mavorixafor is an oral CXCR4 antagonist that mobilizes neutrophils from bone marrow to circulation.

• Previous studies in WHIM syndrome showed mavorixafor increased ANC by ~600 cells/μL and reduced infection rates by 60%.

• FDA approval for mavorixafor in WHIM syndrome supports its potential in CN.

Phase 2 Study Design and Patient Population

• Open-label, six-month trial with 23 participants across monotherapy, stable G-CSF plus mavorixafor, and G-CSF with dose adjustment.

• Interim analysis focused on monotherapy and stable G-CSF groups; most patients had idiopathic or congenital CN.

• The study evaluated ANC increase ≥500 cells/μL, durability, safety, and efficacy in severe CN (baseline ANC <500 cells/μL).