Company: NCNA
Filing Date: 2025-11-05
Form Type: 6-K
Source: 0001193125-25-265824
Chunk: 0

Company: NuCana plc
Filing Date: 2025-11-05
Form: 6-K
Chunk 0
---
### UNITED STATES

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

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

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

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of November 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 November 5, 2025, NuCana plc (the “Company”) issued a press release announcing the issuance of a new patent (ZL 202010794701.2) by the China National Intellectual Property Administration (CNIPA) covering NUC-7738’scomposition of matter. The press release is attached as Exhibit 99.1 hereto. The information in this Report on Form 6-Kshall be deemed to be incorporated by reference into the registration statements on Form F-3,as amended (File Number 333-281576)and Form S-8(File Number 333-223476and File Number 333-248135),and related prospectuses, as such registration statements and prospectuses may be amended from time to time, and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished. The information in the attached Exhibit 99.1 is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended,