Paula Ragan, PhD
CEO and President
Dr. Ragan has been X4’s President and Chief Executive Officer and a member of the X4 Board of Directors since July 2014. She has more than 18 years of experience building companies in the biotechnology industry. Prior to founding X4, Dr. Ragan consulted as Chief Business Officer at Lysosomal Therapeutics Inc., a private biopharmaceutical company, where she led the company’s business development activities. Prior to that, Dr. Ragan held leadership roles in corporate development and operations at Genzyme Corporation, a Sanofi company, where she led strategic partnering efforts for Genzyme’s Rare Disease business and headed the supply chain planning for Genzyme’s flagship commercial products. Other professional roles include business roles at Hydra Biosciences, Oscient Corporation and Celera Corporation. Since 2019, Dr. Ragan is a member of the Board of Directors at Camp4. Dr. Ragan received her B.S. from Tufts University and her Ph.D. from Massachusetts Institute of Technology and completed post-doctoral studies at Harvard Medical School. Read More
Adam Mostafa
Chief Financial Officer
Mr. Mostafa has served as X4’s Chief Financial Officer since September 2018. Prior to joining X4, Mr. Mostafa served as chief financial officer of Abpro Corporation, a biotechnology company focused on antibody therapeutics. Prior to that, Mr. Mostafa was a managing director in the healthcare investment banking group at Cantor Fitzgerald, and was a senior banker in the healthcare investment banking group at Needham & Company. Prior to that, Mr. Mostafa was a vice president in the investment banking group at CRT Capital Group, and was a portfolio management associate in the global stock selection group at AQR Capital. He began his career as an analyst in the healthcare investment banking group at Salomon Smith Barney. Mr. Mostafa earned an A.B. in Economics from Brown University. Read More
Diego Cadavid, MD
Chief Medical Officer
Diego Cadavid, MD, joined the X4 team as Chief Medical Officer in December 2020. He brings more than 22 years of experience in drug development and academic research to X4, having led multiple programs through all phases of clinical development, including small molecules and biologics for the treatment of rare and immunological diseases. Most recently, Dr. Cadavid served as Senior Vice President and Head of Clinical Development at Fulcrum Therapeutics where he led the development of multiple small molecules for the treatment of genetically defined rare diseases, including facioscapulohumeral muscular dystrophy, sickle cell disease and beta-thalassemia. Prior to Fulcrum, Dr. Cadavid held several leadership positions at Biogen over an eight-year tenure, including Senior Medical Director of the multiple sclerosis clinical development group. While at Biogen, he also worked as a consultant at the center for immunology and inflammatory diseases at Massachusetts General Hospital (MGH). Previously, Dr. Cadavid was a faculty member at Rutgers-New Jersey Medical School for over 9 years. Dr. Cadavid holds an MD in medicine and surgery from the Pontificia Universidad Javeriana in Bogotá, Colombia, and completed post-doctoral training in microbiology and immunology at the University of Texas Health Science Center in San Antonio, Texas (UTHSCSA). He completed a clinical neurology residency at Georgetown University and conducted a fellowship in neuropathology at Armed Forces Institute of Pathology, both in Washington, DC. He is board-certified and a U.S. licensed clinical neurologist. Dr. Cadavid has published more than 100 peer review publications, review papers, and book chapters. Read More
Art Taveras, PhD
Chief Scientific Officer
Dr. Art Taveras joined the X4 team as Chief Scientific Officer in October 2020. He brings more than 30 years of experience leading small molecule research and development programs focused on the treatment of cancer, dysregulated immune disorders, neurodegeneration and metabolic diseases. His research and leadership have led to the development of multiple IND candidates and dozens of clinical trials. He joins X4 from CoMET Therapeutics, where he served as Chief Scientific Officer leading the development of treatments for Inborn Errors of Metabolism (IEM) diseases and metabolic disorders. Previously, he was the Founder and Chief Scientific Officer at Transform Therapeutics, a company aiming to discover CXCR2 antagonists for the treatment of cancer and served as President and Chief Scientific Officer at ShangPharma ChemPartner where he supported discovery and clinical portfolios of hundreds of pharmaceutical and biotech companies worldwide. Prior to that, Dr. Taveras was Vice President of Small Molecule Drug Discovery and CMC Development at Biogen Idec, where he led the discovery and development of neurology, immunology and oncology drug candidates at its multiple sites in the U.S. and abroad. He also was Vice President of drug discovery and development at Alantos Pharmaceuticals, which was acquired by Amgen in 2007, where he spearheaded the company's discovery research and built its diabetes and matrix metalloproteinase franchise in the U.S. and Germany. Dr. Taveras began his career with Schering-Plough Corporation and held multiple roles of increasing responsibility in the oncology and immunology drug discovery and research sector over a 14-year period, including leading the discovery of Navarixin®, a CXCR2 antagonist currently in clinical trials in combination with pembrolizumab for the treatment of cancer. He holds 130 issued patents and patent applications and has authored more than 90 scientific publications. Dr. Taveras received his B.S., M.S. and Ph.D. from Rensselaer Polytechnic Institute. Additionally, he attended the college of advancing studies at Boston College. Read More
Mary DiBiase, PhD
Chief Operating Officer
Previously, Dr. DiBiase was the Senior Vice President of Technical Operations and Quality at X4. She has more than 20 years of drug development and technical operations experience in both large and small organizations holding leadership roles in technical development, product operations and program management. Prior to X4 she was VP Technical Operations and Program Management at Epirus Biopharmaceuticals, a small biosimilar company working to expand access to biosimilar products across the globe. Other professional roles include VP Product Operations, Specialty Care Business Unit for Pfizer Global Supply, and multiple positions of increasing responsibility at Biogen including Sr Director CMC Management, Program Executive for Avonex® and Associate Director Pharmaceutical Science and Technology. Dr. DiBiase received her PhD from the University of Rhode Island and her B.Pharm. from the University of London. Read More

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