Company: NCNA
Filing Date: 2025-11-13
Form Type: 6-K
Source: 0001193125-25-280224
Chunk: 0

Company: NuCana plc
Filing Date: 2025-11-13
Form: 6-K
Chunk 0
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### UNITED STATES

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

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 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 13, 2025, NuCana plc (the “Company”) issued a press release announcing its third quarter 2025 financial results. The Company’s unaudited condensed consolidated financial statements as of September 30, 2025 are attached as Exhibit 99.1 and are incorporated by reference herein. The Company’s Management’s Discussion and Analysis of Financial Condition and Results of Operations is attached hereto as Exhibit 99.2, and is incorporated by reference herein. The press release is attached as Exhibit 99.3 hereto and is incorporated by reference herein. The information in the attached Exhibits 99.1 and 99.2 shall 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be amended from time to time, and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.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 99.3 is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities