Arcus Biosciences, Inc.

Item 8.01 Other Events. On October 21, 2026, Arcus Biosciences, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, Leerink Partners LLC and TD Securities (USA) LLC, as representatives of the several underwriters named therein (collectively, the “Underwriters”), relating to the public offering, issuance and sale of 14,285,715 shares of the Company’s common stock (“Common Stock”), at the public offering price of $17.50 per share (the “Offering”). Under the terms of the Underwriting Agreement, the Company also granted the Underwriters an option exercisable for 30 days from the date of the Underwriting Agreement to purchase up to an additional 2,142,857 shares of Common Stock at the public offering price, less underwriting discounts and commissions (the “Underwriters’ Option”). The Underwriters agreed to purchase the shares of Common Stock from the Company at a price of $16.45 per share. On October 23, 2026, the Offering closed and the Company completed the sale and issuance of an aggregate of 16,428,572 shares of Common Stock, including the exercise in full of the Underwriters’ Option. The Company received net proceeds of approximately $269.7 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. The Underwriting Agreement contains customary representations, warranties and covenants by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement and may be subject to limitations agreed upon by the contracting parties, including being qualified by confidential disclosures exchanged between the parties in connection with the execution of the Underwriting Agreement. The Offering was made pursuant to an effective registration statement on Form S-3 (Registration Statement No. 333-293750) and an accompanying prospectus previously filed with the Securities and Exchange Commission and preliminary and final prospectus supplements thereunder. The Underwriting Agreement is filed as Exhibit 1.1 hereto, and the description of the material terms of the Underwriting Agreement is qualified in its entirety by reference to such exhibit. A copy of the opinion of Latham & Watkins LLP relating to the legality of the issuance and sale of the securities in the Offering is attached as Exhibit 5.1 hereto.