Company: NCNA
Filing Date: 2025-04-04
Form Type: DRS
Source: 0000950123-25-003335
Chunk: 70

Company: NuCana plc
Filing Date: 2025-04-04
Form: DRS
Chunk 70
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arrants, or a partner in or owner of such partnership or other pass-through entity. The U.S. federal income tax treatment of each partner of such partnership or owner of such pass-through entity generally will depend upon the status of the partner or owner and the activities of the partnership or other pass-through entity. Prospective purchasers that are partners in a partnership or owners of a pass-through entity holding the ADSs, the Pre-FundedWarrants, or the Warrants are urged to consult their own tax advisers. The discussion below of the U.S. federal income tax consequences to “U.S. Holders” will apply to an investor that is a beneficial owner of ADSs, Pre-FundedWarrants, or Warrants and that is, for U.S. federal income tax purposes,

| • |     | an individual who is a citizen or resident of the United States; |

| • |     | a corporation (or other entity taxable as a corporation for U.S. federal income tax purposes) organized under the 
 laws of the United States, any state therein or the District of Columbia;                                         |

| • |     | an estate whose income is subject to U.S. federal income taxation regardless of its source; or |

| • |     | a trust that (i) is subject to the primary supervision of a court within the United States and subject to                                                                               
 the control of one or more U.S. persons for all substantial decisions or (ii) has a valid election in effect under applicable U.S. Treasury Regulations to be treated as a U.S. person. |

For U.S. federal income tax purposes, a beneficial owner of ADSs generally will be treated as the owner of the underlying ordinary shares represented by such ADSs. Accordingly, deposits or withdrawals of the underlying ordinary shares for ADSs generally will not be subject to U.S. federal income tax. The discussion below assumes that the representations contained in the deposit agreement are true and that the obligations in the deposit agreement and any related agreement will be complied with in accordance with their terms. U.S. Treasury has expressed concerns that parties to whom ADSs are released before shares are delivered to the depositary or 53

Confidential Treatment Requested by Nucana plc

Pursuant to 17 C.F.R. Section 200.83

intermediaries in the chain of ownership between the U.S. Holder of an ADS and the issuer of the security underlying the ADS may be taking actions that are inconsistent with the claiming of
foreign tax credits by U.S.