Company: NCNA
Filing Date: 2025-07-09
Form Type: 6-K
Source: 0001193125-25-156987
Chunk: 1

Company: NuCana plc
Filing Date: 2025-07-09
Form: 6-K
Chunk 1
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 before the Nasdaq Hearings Panel (the
“Panel”). The Company plans to timely request a hearing before the Panel, which request will stay any suspension or delisting action pending the ultimate outcome of the hearing process.

The information contained in this Form 6-K is hereby incorporated by reference into the Company’s Registration
Statement on Form F-3, as amended (File No. 333-281576), and its Registration Statements on Form S-8 (File Nos. 333-223476 and 333-248135).

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereto duly authorized.

| NuCana plc |     |                                 |
| By:        |     | /s/ Ian Webster                 |
| Name:      |     | Ian Webster                     |
| Title:     |     | Interim Chief Financial Officer |

Date: July 9, 2025