Company: RCUS
Filing Date: 2025-10-31
Form Type: 424B5
Source: 0001193125-25-260836
Chunk: 10

Company: Arcus Biosciences, Inc.
Filing Date: 2025-10-31
Form: 424B5
Chunk 10
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 Our shares of common stock are listed on the New York Stock Exchange under the symbol “RCUS.” |

The number of shares of our common stock to be outstanding after this offering is based on 107,101,086 shares of our common stock outstanding as of September 30, 2025, and excludes:

| • |     | 800,000 shares of our common stock sold through our “at the market offerings” under our equity 
 distribution agreement after September 30, 2025 at a weighted-average sales price of $13.3563; |

| • |     | 17,315,226 shares of our common stock issuable upon the exercise of stock options outstanding as of 
 September 30, 2025, at a weighted-average exercise price of $18.6711 per share;                     |

| • |     | 60,300 shares of our common stock issuable upon the exercise of stock options granted after September 30, 
 2025, with an exercise price of $15.05 per share;                                                         |

| • |     | 3,946,206 shares of our common stock issuable upon the vesting and settlement of restricted stock units 
 outstanding as of September 30, 2025;                                                                   |

| • |     | 30,150 shares of common stock issuable upon the vesting and settlement of restricted stock units granted after 
 September 30, 2025;                                                                                            |

S-7

| • |     | up to an aggregate of 3,512,197 shares of common stock reserved for issuance pursuant to future awards under our                                                                                                                        
 2018 Equity Incentive Plan (our “Equity Incentive Plan”), as of September 30, 2025, as well as any annual automatic increases in the number of shares of our common stock reserved for future issuance under the Equity Incentive Plan; |

| • |     | up to an aggregate of 2,566,196 shares of common stock reserved for issuance pursuant to future awards under our 
 2020 Inducement Plan (our “Inducement Plan”), as of September 30, 2025; and                                      |

| • |     | up to an aggregate of 3,224,462 shares of common stock reserved for issuance under our 2018 Employee Stock 
 Purchase Plan (our “Purchase Plan”), as of September 30, 2025.                                             |

In addition, unless we specifically state otherwise, all information in this prospectus supplement