X4 Pharmaceuticals, Inc., a late-stage clinical biopharmaceutical company, focuses on the research, development, and commercialization of novel therapeutics for the treatment of rare diseases. Its lead product candidate is mavorixafor, a small molecule inhibitor of the chemokine receptor C-X-C chemokine receptor type 4 (CXCR4), which is in Phase III clinical trial for the treatment of patients with warts, hypogammaglobulinemia, infections, and myelokathexis syndrome; and Phase II clinical trial to treat congenital, idiopathic, or cyclic neutropenia. The company is also developing X4P-003, a CXCR4 antagonist for the treatment of CXCR4 dependent disorders and primary immunodeficiencies; and X4P-002, a CXCR4 antagonist for the treatment of blood-brain barrier diseases. It has a license agreement with Abbisko Therapeutics Co Ltd. to develop, manufacture, and commercialize mavorixafor in combination with checkpoint inhibitors or other agents in oncology indications. The company is headquartered in Boston, Massachusetts.