X4 Pharmaceuticals, Inc. is a late clinical-stage company, which engages in the development and discovery of novel therapeutics for the treatment of rare diseases and those with limited treatment options. The company is headquartered in Boston, Massachusetts and currently employs 143 full-time employees. The company went IPO on 2017-11-16. The firm 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. The company has developed a small-molecule, oral antagonists of the chemokine receptor C-X-C receptor type 4 (CXCR4). The company 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.