Sonoma Biotherapeutics Appoints Joseph R. Arron, M.D., Ph.D., as Chief Scientific Officer and Mark D. Eisner, M.D., MPH, as Chief Medical Officer

Sonoma Bio

Co-founder Fred Ramsdell, Ph.D., to retire from Chief Scientific Officer position

SOUTH SAN FRANCISCO & SEATTLE – September 29, 2023 – Sonoma Biotherapeutics, Inc., a clinical-stage biotechnology company developing engineered regulatory T cell (Treg) therapies for autoimmune and inflammatory diseases, today announced the appointments of Joseph R. Arron, M.D., Ph.D., as Chief Scientific Officer and Mark D. Eisner, M.D., MPH, as Chief Medical Officer. Sonoma Bio co-founder and Chief Scientific Officer, Fred Ramsdell, Ph.D., will retire and remain a member of the Company’s Scientific Advisory Board.

“Joe and Mark have established track records of driving scientific and clinical strategy to advance novel therapies for patients living with devastating diseases,” said Jeff Bluestone, Ph.D., Co-founder and Chief Executive Officer of Sonoma Biotherapeutics. “We look forward to leveraging their expertise as we enter the clinic with our lead Treg product candidate and continue to advance our pipeline. I’d also like to extend my gratitude to my long-time collaborator and colleague, Fred Ramsdell, for his immense contributions to Sonoma Bio. The company would not be where it is today if it were not for Fred’s seminal discoveries and dogged pursuit of Treg cell therapeutics.”

Dr. Arron, Sonoma Bio’s new CSO, has extensive experience in drug and biomarker discovery and development. He was already a member of the Company’s Scientific Advisory Board. Previously, he served as the Chief Scientific Officer at 23andMe, a genetics-led consumer healthcare and biopharmaceutical company, where he oversaw target discovery, translational research and preclinical development for human diseases related to genetic variation. Prior to 23andMe, Dr. Arron was a Scientist at Genentech for nearly 15 years, and led target discovery, preclinical development and translational research for inflammatory, autoimmune, fibrotic and ophthalmic disorders as Vice President of Immunology Research. Dr. Arron has published more than 100 original articles. He earned his Ph.D. from The Rockefeller University, his M.D. from Weill Medical College of Cornell University and completed undergraduate studies in chemistry at Princeton University.

“I’m thrilled to join Sonoma Bio at this pivotal time for the company and contribute to the development of a new generation of targeted and durable Treg cell therapies,” said Dr. Arron. “I look forward to collaborating with pioneers in immunology and Treg biology, as we proceed down this uncharted path in cell therapy for autoimmune disease.”

Dr. Eisner, Sonoma Bio’s new CMO, brings decades of experience in clinical development and operations in multiple therapeutic areas including immunology, fibrosis, infectious disease, ophthalmology and rare disease. He previously served as the Executive Vice President and Chief Medical Officer at FibroGen, where he led clinical development and operations of the company’s pipeline from Phase I to IV studies and medical affairs. He began his career in the biopharmaceutical industry at Genentech, where he served in clinical and medical leadership positions of increasing responsibility culminating in his role as Senior Vice President, Global Head of Immunology, Infectious Disease and Ophthalmology Product Development. Prior to Genentech, he served on the faculty of University of California, San Francisco for 10 years, first as Associate Professor of Medicine and Anesthesia, then as Clinical Professor of Medicine. He earned his M.D. from the University of Pennsylvania School of Medicine, MPH from the University of California, Berkeley, and his undergraduate degree in human biology from Stanford University. He completed residency training in internal medicine and fellowship training in pulmonary and critical care medicine at the University of California, San Francisco.

“Sonoma Bio is reimagining the chronic treatment paradigm that patients with autoimmune and inflammatory diseases face today,” said Dr. Eisner. “I’m excited to join the team at the forefront of the effort to develop potentially curative Treg cell therapies that could restore long term immune tolerance and bring forth real change for these patient communities.”

About Sonoma Biotherapeutics
Sonoma Biotherapeutics is a clinical-stage biotechnology company developing engineered regulatory T cell (Treg) therapies to treat serious autoimmune and inflammatory diseases by restoring balance to the immune system. Founded by pioneers in Treg biology and cell therapy, the company is employing proprietary platform technologies and approaches to develop a new generation of targeted and durable Treg cell therapies. Sonoma Biotherapeutics is based in South San Francisco and Seattle. For more information, visit and follow on X, formerly Twitter, and LinkedIn.

Brian Crawford
Sonoma Biotherapeutics

Danielle Cantey
Evoke Canale