Company: RCUS
Filing Date: 2025-10-31
Form Type: 424B5
Source: 0001193125-25-260836
Chunk: 17

Company: Arcus Biosciences, Inc.
Filing Date: 2025-10-31
Form: 424B5
Chunk 17
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 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;                             |

S-13

| • |     | 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;                                                                                |

| • |     | up to an aggregate of 3,512,197 shares of common stock reserved for issuance pursuant to future awards under                                                                                             
 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 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 Purchase Plan, as of 
 September 30, 2025.                                                                                         |

To the extent that any options are exercised, restricted stock units vest and settle, new options or restricted stock units are issued under our equity incentive plans or we otherwise issue additional shares of common stock in the future at a price less than the offering price, there may be further dilution to new investors purchasing common stock in this offering. In addition, we may choose to raise additional capital because of market conditions or strategic considerations, even if we believe that we have sufficient funds for our current or future operating plans. If we raise additional capital through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders. S-14

MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S.HOLDERS The following discussion is a summary of the material U.S. federal income tax consequences to Non-U.S.Holders (as defined below)