Company: NCNA
Filing Date: 2025-04-04
Form Type: DRS
Source: 0000950123-25-003335
Chunk: 12

Company: NuCana plc
Filing Date: 2025-04-04
Form: DRS
Chunk 12
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 not limited to, working capital, capital expenditures, investments, acquisitions, should we choose to pursue any, and collaborations See “Use of Proceeds” in this prospectus. |

| Risk factors | You should carefully read the information set forth under “Risk Factors” beginning on page 7 of this prospectus, and incorporated by referenced in this prospectus, before investing in our securities. |

| Reasonable best efforts offering | We have agreed to offer and sell the securities offered hereby to the purchasers through the Placement Agent. The Placement Agent is not required to buy or sell any specific number or dollar amount of the securities offered hereby but will 
 use its reasonable best efforts to solicit offers to purchase the securities offered by this prospectus. See “Plan of Distribution” on page 66 of this prospectus.                                                                              |

| Nasdaq Capital Market symbol | Our ADSs are listed on The Nasdaq Capital Market under the symbol “NCNA”. There is no established trading market for the Pre-Funded Warrants, Series A Warrants or Series B Warrants and we do not           
 expect a trading market to develop. We do not intend to list the on any securities exchange or other trading market. Without a trading market, the liquidity of the Pre-Funded Warrants and Warrants will be 
 extremely limited.                                                                                                                                                                                           |

The number of our ordinary shares to be outstanding immediately after this offering is calculated by reference to our entire issued share capital of 142,037,199 ordinary shares as of December 31, 2024 and excludes as of that date:

| • |     | 17,175,304 ordinary shares issuable upon exercise of outstanding options under our equity compensation plans as 
 of December 31, 2024 at a weighted average exercise price of £2.11 per ordinary share; and                      |

| • |     | 29,123 ordinary shares issued upon exercise of options under our equity incentive plans subsequent to December 
 31, 2024 at an exercise price of £ 0.04 per ordinary share.                                                    |

6

Confidential Treatment Requested by Nucana plc

Pursuant to 17 C.F.R. Section 200.83

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully consider the risks described under “Risk Factors” in our Annual Report on Form 20-F forthe fiscal year ended December 31, 2024, as filed with the SEC, and all other information contained in, or incorporated by reference in