Company: NCNA
Filing Date: 2025-06-27
Form Type: 424B5
Source: 0001193125-25-151464
Chunk: 14

Company: NuCana plc
Filing Date: 2025-06-27
Form: 424B5
Chunk 14
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 connection with securities offered pursuant to this prospectus supplement for any purpose.

In
addition, we have agreed to use a portion of the monthly net proceeds from this offering to cancel outstanding Series A Warrants issued in the May 2025 offering. In connection with any such cancellation, the aggregate payment amount, or Warrant
Cancellation Payment, will be equal to 70% of the monthly net proceeds from this offering. “Net proceeds” means the gross proceeds from this offering, less placement agent commissions, reimbursable expenses payable to the placement agents,
and our offering-related expenses.

S-11

CAPITALIZATION The following table presents our total capitalization and cash and cash equivalents as of March 31, 2025 on:

| • |     | an actual basis, derived from our unaudited condensed consolidated financial statements incorporated by reference 
 into this prospectus; and                                                                                         |

| • |     | a pro forma basis to give effect to the sale and issuance on May 7, 2025, under a registered direct                                                                                                                                                
 offering, of 61,323,375 ordinary shares, and Pre-Funded Warrants to purchase up to 209,826,250 ordinary shares in lieu of ADSs, which were subsequently exercised in full, and accompanying Series A Warrants and                                  
 Series B Warrants as well as the subsequent issuance of 9,117,817,625 ordinary shares pursuant to the exercise of Series A Warrants and the exercise of all Series B Warrants, resulting in net proceeds, after deducting placement agent fees and 
 estimates of other related expenses, of £8.0 million. No adjustments have been made to the pro forma to reflect the fair value of Pre-Funded Warrants, the Series A Warrants or the Series B Warrants                                              
 as at issuance or as at exercise, as required under IFRS.                                                                                                                                                                                          |

You should read the financial data in the following table in conjunction with our unaudited condensed consolidated financial statements, audited consolidated financial statements and related notes incorporated by reference into this prospectus.

|                                                             |     | AS OF MARCH 31, 2025 |          |   |     |           |          |   |
|:------------------------------------------------------------|:----|:---------------------|---------:|:--|:----|:----------|---------:|:--|
|                                                             |     | -Unaudited)          
 (In Thousands        |          |   |     |           |          |   |
|                                                             |     |