Exhibit 99.1

NuCana to Present Data on NUC-7738’s Synergy with PD-1 Inhibitors at the ESMO Congress 2025

EDINBURGH, United Kingdom, September 3, 2025 (GLOBE NEWSWIRE) - NuCana plc (Nasdaq: NCNA) (“NuCana” or the “Company”) announced a presentation at the upcoming annual European Society for Medical Oncology (“ESMO”) congress being held October 17-21, 2025 in Berlin, Germany (the “ESMO Congress 2025”).

The details of NuCana’s presentation at the meeting are as follows:

Abstract Title: Patient Derived Organoids Reveal Synergy Between NUC-7738 and PD-1 Inhibition in Renal Cell Cancer

Poster Number: 1530P

Session: Investigational Immunotherapy

Date: Sunday, October 19, 2025

Presenting Author: H. Abdullah

All regular abstracts accepted for presentation at the ESMO Congress 2025 will be published online via the ESMO website on Monday, October 13 at 6:05 p.m. ET (12:05 a.m. CEST). All accepted abstracts will be published online in the ESMO Congress 2025 Abstract Book, a supplement to the official ESMO journal, Annals of Oncology.

More information regarding the ESMO Congress 2025 can be found at: https://www.esmo.org/meeting-calendar/esmo-congress-2025.

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-7738 and NUC-3373. NUC-7738 is a novel anti-cancer agent that disrupts RNA polyadenylation, profoundly impacts gene expression in cancer cells and targets multiple aspects of the tumor microenvironment. NUC-7738 is in the Phase 2 part of a Phase 1/2 study which is evaluating NUC-7738 as a monotherapy in patients with advanced solid tumors and in combination with pembrolizumab in patients with melanoma. NUC-3373 is a new chemical entity derived from the nucleoside analog 5-fluorouracil, a widely used chemotherapy agent. NUC-3373 is currently being evaluated in a Phase 1b/2 modular study (NuTide:303) 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.

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 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-7738 and NUC-3373; 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, our ability to raise additional capital sufficient to fund our planned operations and 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, 2024 filed with the Securities and Exchange Commission (“SEC”) on March 20, 2025, 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

Andrew Kay

Executive Chairman

+44 131-357-1111

info@nucana.com

ICR Healthcare

Chris Brinzey

+1 339-970-2843

Chris.Brinzey@ICRHealthcare.com