• Dr. Bluestone to serve as Advisor to the Company and remain on Board of Directors
• Dr. Dilly to bring track record in biopharmaceutical leadership, business development and drug development to new leadership role
• CEO transition to drive next stage of growth following positive first-in-human data from SBT-77-7101 trial

Sonoma Biotherapeutics, Inc., a clinical-stage biotechnology company developing engineered regulatory T cell (Treg) therapies for autoimmune and inflammatory diseases, today announced that its Board of Directors has appointed Stephen Dilly, MBBS, PhD, former President and Chief Executive Officer (CEO) of Codexis, Inc., and current Chair of the Codexis Board, as the Company’s new President, CEO and member of the Board of Directors, effective today. The Company also announced that co-founder Jeff Bluestone, PhD, will continue to serve as a member of the Board of Directors and as Advisor to SonomaBio, following his leadership in the Company’s founding, development, and growth since 2019.

The leadership transition follows the Company’s recent announcement of positive interim safety and efficacy results from its first-in-human study of its lead Treg program, SBT-77-7101, in patients with refractory rheumatoid arthritis.

“At SonomaBio, we’ve taken engineered regulatory T-cells from a concept to clinical data that demonstrate the potential of our innovation to become a life-changing treatment for patients. I am immensely proud of all that we have achieved and excited for the Company to build on our momentum for SBT-77-7101 in patients with refractory rheumatoid arthritis,” said Dr. Bluestone. “I believe now is the time for me to make way for new leadership to drive our business to its ultimate goal of delivering innovative therapies to patients. I’m thrilled to welcome Stephen and believe he is the right person, at the right time, to lead our Company. I look forward to partnering with him and the Board in support of our mission to transform autoimmune and inflammatory diseases through curative therapies.”

“SonomaBio’s pipeline has the potential to be a true scientific breakthrough and major advancement for treating and potentially curing patients with chronic immunological conditions, and I have great admiration for Jeff and the entire team,” said Dr. Dilly. “I am honored to join SonomaBio at this critical juncture as we continue to advance our clinical programs. I would like to personally thank Jeff for all he has done to build and drive the company to an important inflection point, and I am grateful for his continued leadership and counsel as Advisor and Board member.”

“On behalf of the Board, I would like to thank Jeff for his years of scientific dedication, boundless energy and impassioned leadership that built SonomaBio into the company that we are today,” said Rick Klausner, MD, Chair of SonomaBio’s Board of Directors. “We are pleased to welcome Stephen as SonomaBio’s next President and Chief Executive Officer and recognize him as a proven leader and biotech veteran with deep experience in building innovative companies.”

Dr. Dilly brings nearly forty years of experience and an exceptional track record of leadership, business development and drug development. Most recently, he served as the Chairman, CEO and President of Codexis, Inc., and continues to serve as Chairman of the Codexis Board. Prior to Codexis, Dr. Dilly served as President and CEO of Sierra Oncology through its sale to GlaxoSmithKline. Previously, Dr. Dilly served as CEO of Aimmune Therapeutics, acquired by Nestle Health Science. Dr. Dilly has served in executive roles at Genentech, Chiron and SmithKline Beecham and has been associated with the development, approval and launch of more than twenty-five marketed drugs across multiple therapeutic areas. He holds both an MBBS and a PhD in Cardiac Physiology from the University of London.

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 immune system balance. Founded by pioneers in Treg biology and cell therapy, including Dr. Fred Ramsdell, whose foundational research in Treg biology was recognized with a 2025 Nobel Prize, Sonoma Biotherapeutics combines deep scientific expertise with proprietary platform technologies to advance a new generation of targeted and durable Treg cell therapies.

In addition to its lead, proprietary Treg program, SBT-77-7101, Sonoma Biotherapeutics is collaborating with Regeneron to advance a pipeline of Treg cell therapies for autoimmune diseases.

For more information, visit sonomabio.com and follow Sonoma Biotherapeutics on X (formerly Twitter) and LinkedIn.

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