X4 Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company. The Company is focused on discovering and developing novel therapeutics for the treatment of rare diseases and those with limited treatment options, with a focus on conditions resulting from dysfunction of the immune system. Its lead clinical candidate is mavorixafor, a small-molecule selective antagonist of chemokine receptor CXCR4, that is being developed as an oral, once-daily therapy. It has developed a pipeline of small-molecule, oral antagonists of the chemokine receptor C-X-C receptor type 4 (CXCR4). It has two pre-clinical candidates: X4P-003, a second-generation CXCR4 antagonist designed to have enhanced properties relative to mavorixafor, potentially enabling opportunities in CXCR4-dependent disorders and primary immunodeficiencies, and X4P-002, a CXCR4 antagonist with a distribution profile and a demonstrated ability to cross the blood-brain barrier.