Company: RCUS
Filing Date: 2025-02-18
Form Type: 424B5
Source: 0001193125-25-028669
Chunk: 12

Company: Arcus Biosciences, Inc.
Filing Date: 2025-02-18
Form: 424B5
Chunk 12
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 vesting and settlement of restricted stock units may result in further dilution of your investment.

S-8

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS This prospectus supplement and accompanying prospectus, and the documents we have filed with the SEC that are incorporated herein by reference, contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Exchange Act. These statements relate to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. Forward-looking statements may include, but are not limited to, statements about:

| • |     | our expectations regarding our relationship with Gilead; |

| • |     | our expectations regarding the uses of the net proceeds from the sale of our common stock in this offering; |

| • |     | our expectations regarding the timing and achievement of our investigational product development activities and                                                                            
 ongoing and planned clinical trials, including initiation of new clinical trials, completion of enrollment and availability and timing for reporting of data from ongoing clinical trials; |

| • |     | our ability to develop intra-portfolio combinations and highly-differentiated small-molecule investigational                                          
 products, including our ability to create small-molecule investigational products with ideal pharmacological properties and desired clinical effects; |

| • |     | our expectations regarding the efficiency and speed with which we can create and advance small-molecule 
 investigational products and develop our investigational products and combination therapies;            |

| • |     | our reliance on third parties to conduct our ongoing and future clinical trials and third-party manufacturers to 
 manufacture and supply our investigational products;                                                             |

| • |     | our expectations regarding the nature of the immuno-oncology pathways we are targeting, the size of the potential 
 patient population and the potential market size;                                                                 |

| • |     | our ability to obtain and maintain control of our combination investigational products and maximize the 
 commercial potential of our investigational products;                                                   |

| • |     | our ability to obtain and maintain regulatory approvals of our investigational products and the potential market 
 opportunities for commercializing our investigational products;                                                  |

| • |     | our ability to retain and recruit key personnel, estimates of our expenses, future revenue,