X4 Pharmaceuticals, Inc is a biopharmaceutical company focused on developing and commercializing novel therapeutics for rare diseases of the immune system. The company's core activities center on the research, development, and commercialization of small-molecule oral antagonists of the chemokine receptor CXCR4, with its lead product mavorixafor. X4 Pharmaceuticals operates within the biotechnology and pharmaceutical industry, specifically targeting rare immunodeficiencies and chronic neutropenic disorders where there are significant unmet medical needs.

X4 Pharmaceuticals generates revenue primarily through the sale of its approved product XOLREMDI (mavorixafor) for the treatment of WHIM syndrome in the United States. The company also earns revenue from licensing agreements, including upfront payments, milestone payments, and royalties from partners such as Norgine for commercialization in Europe, Australia, and New Zealand, and taiba rare for distribution in select Middle East and North African countries. Revenue is derived from product sales to patients via specialty pharmacy partners and from contractual payments tied to regulatory and sales milestones achieved by collaboration partners.

The company operates through a single reportable segment as stated in its corporate information, with all tangible assets held in the United States and no geographical or operational segments disclosed.

X4 Pharmaceuticals holds a pioneering position in the treatment of WHIM syndrome, as XOLREMDI is the first and only FDA-approved drug for this indication in the United States. The company faces competition from injectable therapies such as antibiotics, intravenous immunoglobulin, subcutaneous immunoglobulin, and G-CSF, which are used off-label or as supportive care but are associated with significant treatment-limiting adverse events. X4 Pharmaceuticals' competitive advantage lies in its oral, once-daily formulation of mavorixafor, which offers improved convenience and tolerability compared to existing injectable options, supported by clinical demonstration of efficacy in increasing neutrophil and lymphocyte counts and reducing infection rates.

The company serves patients diagnosed with WHIM syndrome, a rare combined immunodeficiency and congenital neutropenic disorder, primarily in the United States through its XOLREMDI product. X4 Pharmaceuticals also targets patients with chronic neutropenic disorders, including idiopathic, cyclic, and congenital forms, through its ongoing 4WARD Phase 3 clinical trial. The customer base consists of individuals receiving care from hematologists, immunologists, and other specialists managing primary immunodeficiency and neutropenia conditions, supported by partnerships with patient foundations such as the Jeffrey Modell Foundation, International Patient Organisation for Primary Immunodeficiencies, and Immune Deficiency Foundation.