On September 15, 2025, Charles Newton notified Lyell Immunopharma, Inc. (the "Company") of his decision to resign from his position as the Chief Financial Officer and principal financial and accounting officer of the Company, effective October 31, 2025 (the "Resignation Date"). There were no disagreements between Mr. Newton and the Company. The Company plans to conduct a search for Mr. Newton's replacement. The Company and Mr. Newton have entered into a consulting agreement under which Mr. Newton may provide consulting services to the Company following the Resignation Date until April 30, 2026 or any earlier termination of the consultancy by either party.