Arcus Biosciences, Inc.

On August 5, 2026, the Company and Gilead entered into an Amended and Restated Investor Rights Agreement (2026 Amended and Restated IRA), which amends and restates in its entirety the Amended & Restated Investor Rights Agreement entered into on January 29, 2024. Pursuant to the 2026 Amended and Restated IRA, Gilead no longer has the right to designate any directors to the Company’s Board of Directors. Concurrent with the execution of the 2026 Amended and Restated Investor Rights Agreement, Dietmar Berger, MD, Ph.D., Johanna Mercier and Linda Higgins, Ph.D. each resigned from the Board, effective as of August 5, 2026. The Board approved a reduction in the size of the Board from eleven to eight directors immediately upon effectiveness of the resignations, none of which were a result of any disagreement with the Company. The foregoing description of the 2026 Amended and Restated IRA does not purport to be complete and is qualified in its entirety by reference to the full text of the 2026 Amended and Restated IRA, which the Company expects to file as an exhibit to its Quarterly Report on Form 10-Q for the quarter ending September 30, 2026.

Rule 10b5-1 Trading Arrangements

Theadoption, modification ortermination of contracts, instructions or written plans for the purchase or sale of our securities by our Section 16 officers and directors for the three months ended June 30, 2026, which are intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act, were as follows: