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 May 2023

(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 May 12, 2023, NuCana plc (the “Company”) issued a press release announcing that it has received written notification from The Nasdaq Stock Market indicating that the Company is not in compliance with the minimum $1.00 per share bid price requirement. The press release is attached as Exhibit 99.1 hereto and is incorporated by reference herein.

The information in this Form 6-K and in the attached Exhibit 99.1 shall be deemed to be incorporated by reference into the registration statements on Form F-3 (File Number 333-258491) and Form S-8 (File Number 333-223476 and 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be amended from time to time, and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

Exhibits

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.

Date: May 12, 2023

Exhibit 99.1

NuCana Announces Receipt of Nasdaq Notice

Edinburgh, United Kingdom, May 12, 2023 (GLOBE NEWSWIRE) – NuCana plc (NASDAQ: NCNA) announced that it received written notification (the “Notification Letter”) from The Nasdaq Stock Market LLC (“Nasdaq”) dated May 9, 2023, indicating that, based upon a closing bid price of less than $1.00 per share for the Company’s American Depositary Shares (“ADSs”) for the prior 30 consecutive business day period, the Company no longer satisfies Nasdaq Listing Rule 5450(a)(1).

The Notification Letter has no immediate effect on the listing of the ADSs, and they will continue to trade on The Nasdaq Global Select Market under the symbol “NCNA”.

Pursuant to Nasdaq Listing Rule 5810(c)(3)(A), the applicable grace period to regain compliance is 180 days, or until November 6, 2023. The Company intends to monitor the closing bid price of its ADSs during this grace period and will consider its options in order to regain compliance with The Nasdaq Global Select Market minimum bid price requirement. The Company can cure this deficiency if the closing bid price of its common stock is $1.00 per share or higher for at least ten consecutive business days during the grace period. In the event the Company does not regain compliance within the 180-day grace period, and it meets all other listing standards and requirements, the Company may be eligible for an additional 180-day grace period.

The Company intends to regain compliance within the applicable compliance period and is currently evaluating its options to do so. During this time, the Company’s ADSs will continue to be listed and trade on The Nasdaq Global Select Market. If the Company is unable to regain compliance prior to November 6, 2023, it may seek to transfer its listing to The Nasdaq Capital Market, provided that it meets the continued listing requirements for such market, other than the bid price requirement, at which time the Company may be provided with an additional period during which it would seek to regain compliance with the bid price requirement. The Company’s business and operations are not affected by the receipt of the Notification Letter.

About NuCana

NuCana is a clinical-stage biopharmaceutical company focused on significantly improving treatment outcomes for patients with cancer by applying our ProTide technology to transform some of the most widely prescribed chemotherapy agents, nucleoside analogs, into more effective and safer medicines. While these conventional agents remain part of the standard of care for the treatment of many solid and hematological tumors, they have significant shortcomings that limit their efficacy and they are often poorly tolerated. Utilizing our proprietary technology, we are developing new medicines, ProTides, designed to overcome the key limitations of nucleoside analogs and generate much higher concentrations of anti-cancer metabolites in cancer cells. NuCana’s pipeline includes NUC-3373 and NUC-7738. NUC-3373 is a new chemical entity derived from the nucleoside analog 5-fluorouracil, a widely used chemotherapy agent. NUC-3373, in combination with other agents, is in a Phase 1b/2 study in patients with metastatic colorectal cancer. NuCana has also initiated a randomized Phase 2 study of NUC-3373, in combination with other agents, for the second-line treatment of patients with advanced colorectal cancer. In addition, NuCana has initiated a Phase 1b/2 modular study of NUC-3373 in combination with the PD-1 inhibitor pembrolizumab for patients with advanced solid tumors and in combination with docetaxel for patients with lung cancer. NUC-7738 is a transformation of 3’-deoxyadenosine, a novel anti-cancer nucleoside analog. NUC-7738 is in the Phase 2 part of a Phase 1/2 study in patients with advanced solid tumors which is evaluating NUC-7738 as a monotherapy and in combination with pembrolizumab.

Forward-Looking Statements

This press release may contain “forward-looking” statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are based on the beliefs and assumptions and on information currently available to management of NuCana plc (the “Company”). All statements other than statements of historical fact contained in this press release are forward-looking statements, including statements concerning the Company’s planned and ongoing clinical studies for the Company’s product candidates and the potential advantages of those product candidates, including NUC-3373 and NUC-7738; the initiation, enrollment, timing, progress, release of data from and results of those planned and ongoing clinical studies; the Company’s goals with respect to the development, regulatory pathway and potential use, if approved, of each of its product candidates; and the utility of prior non-clinical and clinical data in determining future clinical results. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “should,” “expects,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negative of these terms or other comparable terminology. Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause the Company’s actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks and uncertainties include, but are not limited to, the risks and uncertainties set forth in the “Risk Factors” section of the Company’s Annual Report on Form 20-F for the year ended December 31, 2022 filed with the Securities and Exchange Commission (“SEC”) on April 4, 2023, and subsequent reports that the Company files with the SEC. Forward-looking statements represent the Company’s beliefs and assumptions only as of the date of this press release. Although the Company believes that the expectations reflected in the forward-looking statements are reasonable, it cannot guarantee future results, levels of activity, performance or achievements. Except as required by law, the Company assumes no obligation to publicly update any forward-looking statements for any reason after the date of this press release to conform any of the forward-looking statements to actual results or to changes in its expectations.

For more information, please contact:

NuCana plc

Hugh S. Griffith

Chief Executive Officer

+44 131 357 1111

info@nucana.com

ICR Westwicke

Chris Brinzey

+1 339-970-2843

chris.brinzey@westwicke.com