Company: NCNA
Filing Date: 2025-04-23
Form Type: 6-K
Source: 0001193125-25-091437
Chunk: 0

Company: NuCana plc
Filing Date: 2025-04-23
Form: 6-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of April 2025

(Commission File No. 001-38215)

### NUCANA PLC
(Translation of registrant’s name into English)

3 Lochside Way

Edinburgh EH12 9DT

United Kingdom

(Address of registrant’s principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under
cover Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101 (b) (1): ☐

Indicate by check mark if the registrant is
submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101 (b) (7): ☐

Other Events On April 23, 2025, NuCana plc (the “Company”) held a General Meeting (the “GM”) at Lochside House, 3 Lochside Way, Edinburgh, EH12 9DT, United Kingdom. All of the resolutions set out in the Company’s notice of the GM dated March 18, 2025 and furnished on Form 6-Kwith the Securities and Exchange Commission on March 18, 2025 were duly proposed and passed. 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, thereunto duly authorized.

| NuCana plc |     |                         |
| By:        |     | /s/ Hugh S. Griffith    |
| Name:      |     | Hugh S. Griffith        |
| Title:     |     | Chief Executive Officer |

Date: April 23, 2025