Press Releases

Rheos Medicines Appoints Barbara S. Fox as Chief Executive Officer

CAMBRIDGE, Mass, October 21, 2019 – Rheos Medicines, a biopharmaceutical company harnessing insights in immunometabolism to create a new class of therapeutics for patients with severe autoimmune disorders, inflammatory diseases and cancer, today announced the appointment of industry veteran Barbara S. Fox, Ph.D., to Chief Executive Officer.  Dr. Fox succeeds interim Chief Executive Officer, Abbie Celniker, Ph.D., a partner at Third Rock Ventures, who will remain Chairman of Rheos Medicines’ board of directors.

“We are delighted to welcome Barbara to the team and believe her track record makes her an ideal fit as Rheos Medicines’ Chief Executive Officer,” said Dr. Celniker. “We are confident that Barbara’s expertise in building and leading organizations will be an indispensable asset for Rheos and will propel the Company as it develops precision medicines for autoimmunity and other immune-mediated diseases.”

Dr. Fox brings more than 25 years of biopharmaceutical leadership expertise to Rheos Medicines.  She joins the Company from Tilos Therapeutics, a Lexington, MA-based biotech company developing antibody-based therapies for oncology and immune-mediated diseases. Dr. Fox served as Chief Executive Officer at Tilos and led the successful acquisition of the company by Merck in June of this year.  Previous positions include Entrepreneur-in-Residence at Partners Innovation Fund, Founder and Chief Executive Officer of Avaxia Biologics, Founder and Chief Scientific Officer of Recovery Pharmaceuticals, and VP, Discovery and Immunology at ImmuLogic Pharmaceutical Corp.  Prior to ImmuLogic, Dr. Fox was an Associate Professor of Rheumatology at the University of Maryland School of Medicine.  Dr. Fox received her A.B. in Chemistry from Bryn Mawr College, her Ph.D. in Chemistry from the Massachusetts Institute of Technology and trained as a post-doc in Cellular Immunology at the National Institutes of Health.

“Rheos Medicines is pioneering and industrializing the emerging field of immunometabolism, and I am thrilled to be joining at such a pivotal time in the Company’s evolution,” said Dr. Fox. “Rheos’ scientific founders and passionate scientists are leaders in the field, and their groundwork has established an incredible foundation on which to build upon.  I look forward to working with the Rheos team as we leverage the Company’s proprietary immunometabolism product engine to unlock a new frontier in drug discovery.” 

About Rheos Medicines

Rheos Medicines is a biopharmaceutical company harnessing insights in immunometabolism to develop novel therapeutics for patients with severe autoimmune disorders, inflammatory diseases and cancer. Our approach targets the underlying intracellular metabolism of immune cells and has the potential to unlock a new frontier in drug discovery for immune-mediated disease. Through a proprietary platform and product engine that integrates multiple “omic” datasets, we systematically define the biologic links between immune cell metabolism and function and simultaneously identify new drug targets and biomarkers of disease to bring precision to the treatment of immune-mediated diseases. We have assembled leading scientists whose discoveries opened the field of immunometabolism, clinicians with a deep understanding of immune-mediated diseases, and an experienced biotech leadership team. Rheos was founded by Third Rock Ventures and is located in Cambridge, MA. For more information, please visit 


Gad Soffer
Chief Operating Officer

John Grimaldi, Burns McClellan
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Robert Flamm, Ph.D., Burns McClellan
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