Exhibit 99.1 Arcus Biosciences Reports Fourth-Quarter and Full-Year 2023 Financial Results and Provides a Pipeline Update HAYWARD, Calif. – (BUSINESS WIRE) – February 21, 2024 – Arcus Biosciences, Inc. (NYSE:RCUS), a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for people with cancer, today reported financial results for the fourth quarter and full year ended December 31, 2023, and provided a pipeline update on its clinical- stage ...