Company: CYTK
Filing Date: 2025-08-07
Form Type: S-8
Source: 0001193125-25-175412
Chunk: 3

Company: CYTOKINETICS INC
Filing Date: 2025-08-07
Form: S-8
Chunk 3
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 the Company’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on August 3, 2023. |

| (7) | Incorporated by reference to Exhibit 4.1 to the Company’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May 9, 2007. |

| (8) | Incorporated by reference to Appendix A of the Company’s definitive proxy statement, filed with the 
 Securities and Exchange Commission on April 10, 2025.                                               |

SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of South San Francisco, State of California, on this seventh day of August, 2025.

| CYTOKINETICS, INCORPORATED |     |                                       |
| By:                        |     | /s/ Robert I. Blum                    |
|                            |     | Robert I. Blum                        |
|                            |     | President and Chief Executive Officer 
 (Principal Executive Officer)         |

POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Robert I. Blum, Sung Lee and John Faurescu jointly and severally, as his or her attorneys-in-fact,with full power of substitution in each, for him or her in any and all capacities to sign any amendments to this Registration Statement on Form S-8,and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact,or his or her substitutes, may do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

| Signature                       
 /s/ Robert I. Blum              
 Robert I. Blum                  |     | Title                                                          
 President, Chief Executive Officer and Director                
 (Principal Executive Officer)                                  |     | Date           
 August 7, 2025 |
|:--------------------------------|:----|:---------------------------------------------------------------|:----|:---------------|
| /s/