UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____________to _______________ Commission File Number: 001-38419 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 Arcus Biosciences, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 47-3898 ...