Company: WHWK
Filing Date: 2025-01-31
Form Type: DEFM14A
Source: 0001193125-25-018470
Chunk: 758

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-01-31
Form: DEFM14A
Chunk 758
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 Company with respect to the Private Placement. Annex A sets forth definitions for capitalized terms used in this letter agreement that are not defined in the body of this letter agreement. Those definitions are a part of this letter agreement. In consideration of the foregoing, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned hereby agrees that, during the Lock-upPeriod, the undersigned will not (and, if the undersigned is a natural person, will cause any Family Member not to), without the prior written consent of Jefferies, which may withhold its consent in its sole discretion:

| • |     | Sell or Offer to Sell any Shares or Related Securities currently or hereafter owned either of record or  
 beneficially (as defined in Rule 13d-3 under the Exchange Act) by the undersigned or such Family Member, |

| • |     | enter into any Swap, |

| • |     | make any demand for, or exercise any right with respect to, the registration under the Securities Act of the                                                                                                             
 offer and sale of any Shares or Related Securities, or cause to be filed a registration statement, prospectus or prospectus supplement (or an amendment or supplement thereto) with respect to any such registration, or |

| • |     | publicly announce any intention to do any of the foregoing. |

The foregoing will not apply to (i) the offer and sale of Shares and Related Securities pursuant to the Private Placement or (ii) the inclusion of any Shares (including Shares subject to Related Securities) purchased in the Private Placement in the registration statement that is contemplated to be filed with the SEC by the Company to register the resale of the Shares (including Shares subject to Related Securities) purchased in the Private Placement (the “ Resale Registration Statement”), provided that any such Shares may not be sold pursuant to the Resale Registration Statement during the Lock-upPeriod. In addition, the foregoing restrictions will not apply to the transfer of Shares or Related Securities:

| i. | as a bona fide gift or gifts, |

| ii. | by will or intestacy, |

D-53

| iii. | to any trust or other entities formed for the direct or indirect benefit of the undersigned or a Family Member 
 of the undersigned,                                                                                            |

| iv. | to any Family Member, |

| v. | if the undersigned is a trust, to a trustor, trustee or beneficiary of the trust or to the estate of a 
 beneficiary of such