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 2021

(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 19, 2021, NuCana plc (the “Company”) issued a press release announcing its first quarter 2021 financial results. The Company’s unaudited condensed consolidated financial statements as of March 31, 2021 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 as Exhibit 99.2 hereto 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 (File Number 333-227624) 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be amended from time to time, and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

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 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, or the Exchange Act, except as otherwise set forth herein or as shall be expressly set forth by specific reference in such a filing.

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 19, 2021

Exhibit 99.1

NUCANA PLC

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

The accompanying notes form an integral part of these unaudited condensed consolidated financial statements.

NUCANA PLC

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS

The accompanying notes form an integral part of these unaudited condensed consolidated financial statements.

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NUCANA PLC

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

AS AT

The accompanying notes form an integral part of these unaudited condensed consolidated financial statements.

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NUCANA PLC

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

The accompanying notes form an integral part of these unaudited condensed consolidated financial statements.

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NUCANA PLC

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

The accompanying notes form an integral part of these unaudited condensed consolidated financial statements.

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NUCANA PLC

NOTES TO THE UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

1. General information

NuCana plc (“NuCana” or the “Company”) is a clinical-stage biopharmaceutical company developing a portfolio of new medicines to treat cancer. NuCana is harnessing the power of phosphoramidate chemistry to generate new medicines called ProTides. These compounds have the potential to improve cancer treatment by enhancing the efficacy and safety of several current standards of care.

The Company has ordinary shares in the form of American Depositary Shares (“ADSs”) registered with the US Securities and Exchange Commission (the “SEC”) and has been listed on The Nasdaq Global Select Market (“Nasdaq”) since October 2, 2017. The Company is incorporated in England and Wales and domiciled in the United Kingdom. The Company’s registered office is located at 77/78 Cannon Street, London EC4N 6AF, United Kingdom and its principal place of business is located at 3 Lochside Way, Edinburgh, EH12 9DT, United Kingdom.

The Company has two wholly owned subsidiaries, NuCana, Inc. and NuCana BioMed Trustee Company Limited (together referred to as the “Group”).

The financial information presented in these unaudited condensed consolidated financial statements does not constitute the Group’s statutory accounts within the meaning of section 434 of the U.K. Companies Act 2006.

The Group’s statutory accounts for the year ended December 31, 2020 have not yet been reported on by the Company’s auditor or delivered to the Registrar of Companies. The Company filed its Annual Report on Form 20-F for the year ended December 31, 2020 with the SEC on March 4, 2021, which included the Company’s Consolidated Financial Statements for its fiscal year ended December 31, 2020. Those financial statements have been reported on by the Company’s auditor. The report of the auditor was (i) unqualified and (ii) did not include a reference to any matters to which the auditors drew attention by way of emphasis without qualifying their report.

2. Significant accounting policies

Basis of preparation

The unaudited condensed consolidated financial statements (the “financial statements”) for the three months ended March 31, 2021 have been prepared in accordance with International Accounting Standard 34, “Interim Financial Reporting” (“IAS 34”). The significant accounting policies and methods of computation applied in the preparation of the financial statements are consistent with those applied in the Company’s annual financial statements for the year ended December 31, 2020. No new standards, amendments or interpretations have had an impact on the financial statements for the three months ended March 31, 2021. The financial statements comprise the financial statements of the Group at March 31, 2021. The financial statements are presented in pounds sterling, which is also the Company’s functional currency. All values are rounded to the nearest thousand, except where otherwise indicated.

The financial statements do not include all the information and disclosures required in the annual financial statements, and should be read in conjunction with the Company’s annual financial statements for the year ended December 31, 2020.

In the opinion of management, these unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of the results of operations, financial position and cash flows. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results that can be expected for the Company’s fiscal year ending December 31, 2021.

Going concern

In common with many companies in the biopharmaceutical sector, the Company incurs significant expenditure in its early years as it researches and develops its potential products for market.

The Company’s board of directors, having reviewed the operating budgets and development plans, considers that the Company has adequate resources to continue in operation for the foreseeable future. The board of directors is therefore satisfied that it is appropriate to adopt the going concern basis of accounting in preparing the financial statements. The Company believes that its cash and cash equivalents of £78.6 million at March 31, 2021 will be sufficient to fund its current operating plan for at least the next 12 months. Further, the directors have conducted an assessment of the impact of COVID-19 on the going concern status of the Company and have concluded that it will not have a significant negative impact on the cash outflows of the Company over the period assessed for going concern purposes.

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As the Company continues to incur losses, the transition to profitability is dependent upon the successful development, approval and commercialization of its product candidates and achieving a level of revenues adequate to support its cost structure. The Company may never achieve profitability, and unless and until it does, it will continue to need to raise additional capital. There can be no assurances, however, that additional funding will be available on acceptable terms.

COVID-19

In response to the COVID-19 pandemic, all of the Company’s offices have been closed with employees continuing their work outside of the offices and the Company has restricted on-site staff access to only those required to execute their job responsibilities.

During the early months of the pandemic the Company announced that there was some temporary interruption to the enrollment of new patients in the Company’s ongoing clinical trials. In May 2020, the Company further announced that enrollment of new patients in the Company’s clinical trials had re-commenced. While the Company continues to evaluate the impact of COVID-19 on its operations, the Company believes that this pandemic will inevitably cause some delays to the timing of initiation and completion of its clinical trials. The Company is continuing to monitor the impact of COVID-19.

COVID-19 has had no impact on the judgements and estimates used in the preparation of these financial statements.

Judgements and estimates

The accounting estimates and judgements made by management in applying the Group’s accounting policies that have the most significant effect on the amounts included within these financial statements were the same as those that applied to the annual financial statements for the year ended December 31, 2020.    

3. Income tax

The income tax credit recognized primarily represents the U.K. research and development tax credit. In the United Kingdom, the Company is able to surrender some of its losses for a cash rebate of up to 33.35% of expenditure related to eligible research and development projects.

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4. Basic and diluted loss per share

Basic loss per share is calculated by dividing the loss for the period attributable to the equity holders of the Company by the weighted average number of shares outstanding during the period.

The potential shares issued through equity settled transactions were considered to be anti-dilutive as they would have decreased the loss per share and were therefore excluded from the calculation of diluted loss per share.

5. Intangible assets

Intangible assets comprise patents with a carrying value of £4.6 million as of March 31, 2021 (as of December 31, 2020: £4.6 million) and computer software with a carrying value of £0.2 million as of March 31, 2021 (as of December 31, 2020: £0.2 million).

During the three months ended March 31, 2021, the Company acquired intangible assets with a cost of £0.1 million in relation to patents. There were no disposals of intangible assets in the three months ended March 31, 2021.

6. Cash and cash equivalents

Cash and cash equivalents comprise cash at banks with deposit maturity terms of three months or less, which is subject to insignificant risk of changes in value. Cash at banks earns interest at fixed or variable rates based on the terms agreed for each account.

7. Share-based payments

The Company has six share-based payment plans for employees, directors and consultants. The share options granted will be settled in equity. Options granted under each of the six plans have a maximum life of 10 years. If the Company determines, and at its discretion, an arrangement may be made under the 2020 Long-Term Incentive Plan to substitute the right to acquire shares with a cash alternative of equivalent value.

As detailed in the table below, during the three months ended March 31, 2021, 1,501,663 share options were granted under the 2020 Long-Term Incentive Plan (three months ended March 31, 2020: no share options granted). Options granted under this plan will vest if the option holder remains under respective contract of employment or contract of service for the agreed vesting period. The share options granted in the period will vest over a period of up to four years.

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The fair values of options granted were determined using the Black-Scholes model that takes into account factors specific to the share incentive plan such as the assumption that the options are exercised at a point in time of up to two years after vesting. This has been incorporated into the measurement by means of actuarial modelling. As NuCana plc was unlisted until October 2, 2017, it is not possible to derive historical volatility from the Company’s ADSs prior to October 2017. For options with an estimated life of greater than three years, the underlying expected volatility was determined by using the average of the historical volatility of similar listed entities as a proxy. Options granted with an estimated life of three years or less, have been valued using the Company’s own historical volatility rates.

For the three months ended March 31, 2021, the Company has recognized £1.8 million of share-based payment expense in the statement of operations (three months ended March 31, 2020: £0.9 million).

8. Share capital and share premium

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9. Contingent liabilities

Under its U.K. share-based payment plan, the Company granted unapproved share options that have fully vested. If and when these share options are exercised, the Company will be liable for the Employer Class 1 National Insurance payable to HMRC in the United Kingdom. This contingent liability will be determined based on the market value of the shares on exercise less the exercise price paid by the option holders, at the prevailing rate of Employer National Insurance (currently 13.8%). Based on the closing price of the Company’s ADSs on the Nasdaq Global Select Market on March 31, 2021, the last trading day of the period to which these financial statements relate, and assuming full exercise of all outstanding and vested unapproved share options on that date, the Employer National Insurance contingent liability would have been £0.8 million (December 31, 2020: £0.8 million).

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Exhibit 99.2

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of financial condition and results of operations together with the unaudited condensed consolidated financial statements and the related notes to those statements included as Exhibit 99.1 to this Report on Form 6-K submitted to the Securities and Exchange Commission, or the SEC, on May 19, 2021. We also recommend that you read our discussion and analysis of financial condition and results of operations together with our audited financial statements and the notes thereto, and the section entitled “Risk Factors”, each of which appear in our Annual Report on Form 20-F for the year ended December 31, 2020 filed with the SEC on March 4, 2021 (the “Annual Report”).

We present our unaudited condensed consolidated financial statements in pounds sterling and in accordance with International Accounting Standard 34, “Interim Financial Reporting,” or IAS 34, which may differ in material respects from generally accepted accounting principles in other jurisdictions, including generally accepted accounting principles in the United States, or U.S. GAAP.

Unless otherwise indicated or the context otherwise requires, all references to “NuCana,” the “Company,” “we,” “our,” “us” or similar terms refer to NuCana plc and its consolidated subsidiaries.

The statements in this discussion regarding industry outlook, our expectations regarding our future performance, liquidity and capital resources and other non-historical statements are forward-looking statements. 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 our Annual Report and any subsequent reports that we file with the SEC.

Company Overview

We are a clinical-stage biopharmaceutical company focused on significantly improving treatment outcomes for cancer patients 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, their efficacy is limited by cancer cell resistance mechanisms and they are often poorly tolerated. Utilizing our proprietary technology, we are developing new medicines, ProTides, designed to overcome key cancer resistance mechanisms and generate much higher concentrations of anti-cancer metabolites in cancer cells. Our most advanced ProTide candidates, Acelarin^® and NUC-3373, are new chemical entities derived from the nucleoside analogs gemcitabine and 5-fluorouracil, respectively, two widely used chemotherapy agents. Acelarin is currently being evaluated in a Phase 3 clinical trial for patients with biliary tract cancer. In May 2021, the Phase 3 clinical trial for patients with metastatic pancreatic cancer for which enrollment had been suspended was closed. NUC-3373 is currently in a Phase 1 clinical trial in patients with advanced solid tumors and a Phase 1b clinical trial in patients with advanced colorectal cancer. Our third ProTide, NUC-7738, is a transformation of a novel nucleoside analog (3’-deoxyadenosine) that has never been successfully developed or approved as a chemotherapy but has shown potent anti-cancer activity in preclinical studies. We are evaluating NUC-7738 in a Phase 1 clinical trial for patients with advanced solid tumors. We have retained worldwide rights to these lead product candidates as well as our preclinical product candidates, all of which we refer to as ProTides.

COVID-19

During the early months of the pandemic we announced that there was some temporary interruption to the enrollment of new patients in our ongoing clinical trials. In May 2020, we further announced that enrollment of new patients in our clinical trials had re-commenced. While we continue to evaluate the impact of COVID-19 on our operations, we believe that this pandemic will inevitably cause some delays to the timing of initiation and completion of our clinical trials. We continue to monitor the impact of COVID-19.

Financial Operations Overview

Revenues

We do not have any approved products. Accordingly, we have not generated any revenue, and we do not expect to generate any revenue from the sale of any products unless and until we obtain regulatory approvals for, and commercialize any of, our product candidates. In the future, we will seek to generate revenue primarily from product sales and, potentially, regional or global collaborations with strategic partners.

Operating Expenses

We classify our operating expenses into two categories: research and development expenses and administrative expenses. Personnel costs, including salaries, benefits, bonuses and share-based payment expense, comprise a component of each of these expense categories. We allocate expenses associated with personnel costs based on the function performed by the respective employees.

Research and Development Expenses

The largest component of our total operating expenses since our inception has been costs related to our research and development activities, including the preclinical and clinical development of our product candidates.

Research and development costs are expensed as incurred. Our research and development expense primarily consists of:

The successful development of our ProTides is highly uncertain. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later stage clinical trials. Accordingly, we expect research and development costs to increase significantly for the foreseeable future as programs progress. However, we do not believe that it is possible at this time to accurately project total program specific expenses through commercialization. We are also unable to predict when, if ever, material net cash inflows will commence from our product candidates to offset these expenses. Our expenditures on current and future preclinical and clinical development programs are subject to numerous uncertainties in timing and cost to completion.

The duration, costs and timing of clinical trials and development of our product candidates will depend on a variety of factors including:

We track research and development expenses on a program-by-program basis for both clinical-stage and preclinical product candidates. Manufacturing and non-clinical research and development expenses are assigned or allocated to individual product candidates, where appropriate.

Administrative Expenses

Administrative expenses consist of personnel costs, allocated expenses and other expenses for outside professional services, including legal, audit and accounting services. Personnel costs consist of salaries, bonuses, benefits and share-based payment expense. Other administrative expenses include office related costs, professional fees and costs of our information systems. We anticipate that our administrative expenses will continue to increase in the future as we increase our headcount to support our continued research and development and potential commercialization of our product candidates. We also incur expenses as a public company, including expenses related to compliance with the rules and regulations of the SEC and The Nasdaq Global Select Market, additional insurance expenses, and expenses related to investor relations and other administrative and professional services.

Net Foreign Exchange Gains (Losses)

Net foreign exchange gains (losses) primarily includes gains or losses on cash held in U.S. dollars.

Finance Income

Finance income relates to interest earned on our cash and cash equivalents.

Income Tax Credit

We are subject to corporate taxation in the United Kingdom and our wholly owned U.S. subsidiary, NuCana, Inc., is subject to corporate taxation in the United States. Due to the nature of our business, we have generated losses since inception in the United Kingdom. Our income tax credit recognized represents the sum of the research and development tax credits recoverable in the United Kingdom and in the United States, and income tax payable in the United States.

As a company that carries out extensive research and development activities, we benefit from the U.K. and U.S. research and development tax credit regimes. In the United Kingdom, we are able to surrender some of our losses for a cash rebate of up to 33.35% of eligible expenditures on qualifying research and development projects. In the United States, we are able to offset the research and development credits against corporation tax payable. Qualifying expenditures in the United Kingdom largely comprise clinical trial and manufacturing costs, employment costs for relevant staff and consumables incurred as part of research and development projects. In the United Kingdom, where we receive the larger proportion of the research and development credit, certain subcontracted qualifying research and development expenditures are eligible for a cash rebate of up to 21.68%. A large portion of costs relating to our research and development, clinical trials and manufacturing activities are eligible for inclusion within these tax credit cash rebate claims.

We may not be able to continue to claim research and development tax credits in the United Kingdom in the future under the current research and development tax credit scheme because we may no longer qualify as a small or medium-sized company.

Results of Operations

Comparison of the Three Months Ended March 31, 2021 and March 31, 2020

The following table summarizes the results of our operations for the three months ended March 31, 2021 and 2020.

Research and Development Expenses

Research and development expenses were £8.7 million for the three months ended March 31, 2021 as compared to £5.9 million for the three months ended March 31, 2020, an increase of £2.8 million. The increase resulted primarily from higher expenses incurred related to clinical trials of £4.2 million in the three months ended March 31, 2021, compared with £3.1 million in the three months ended March 31, 2020. Non-clinical and manufacturing costs increased by £0.6 million for the three months ended March 31, 2021 as compared to the three months ended March 31, 2020. Other research and development costs increased in the three months ended March 31, 2021 by £1.1 million consistent with higher share-based payment expenses and patent costs.

The following table gives a breakdown of the research and development costs incurred by product candidate for the three months ended March 31, 2021 and 2020:

Administrative Expenses

Administrative expenses were £2.1 million for the three months ended March 31, 2021 as compared to £1.6 million for the three months ended March 31, 2020, an increase of £0.5 million. The increase was primarily related to higher share-based payment expenses and insurance costs, partly offset by lower professional fees.

Net Foreign Exchange (Losses) Gains

For the three months ended March 31, 2021, we reported a net foreign exchange loss of £0.7 million as compared to a net foreign exchange gain of £2.1 million for the three months ended March 31, 2020. In the three months ended March 31, 2021, the loss arose from cash balances held in U.S. dollars and the U.S. dollar depreciating relative to the U.K. pound sterling. Conversely in the three months ended March 31, 2020, the gain arose from cash balances held in U.S. dollars and the U.S. dollar appreciating relative to the U.K. pound sterling.

Finance Income

Finance income represents bank interest and was £24,000 for the three months ended March 31, 2021 and £0.1 million for the three months ended March 31, 2020. The decrease in bank interest resulted from lower rates of interest being earned on cash deposits.

Income Tax Credit

The income tax credit for the three months ended March 31, 2021, which is largely comprised of U.K. research and development tax credits, amounted to £1.7 million as compared to £1.3 million for the three months ended March 31, 2020. The increase in the income tax credit was primarily attributable to an increase in our eligible research and development expenses.

Liquidity and Capital Resources

Overview

Since our inception, we have incurred significant operating losses and negative cash flows. We anticipate that we will continue to incur losses for at least the next several years. We expect that our research and development and administrative expenses will increase in connection with conducting clinical trials and seeking marketing approval for our product candidates, as well as costs associated with operating as a public company. As a result, we will need additional capital to fund our operations, which we may obtain from additional equity financings, debt financings, research funding, collaborations, contract and grant revenue or other sources.

As of March 31, 2021 and December 31, 2020, we had cash and cash equivalents of £78.6 million and £87.4 million, respectively. We do not currently have any approved products and have never generated any revenue from product sales. To date we have financed our operations primarily through the issuances of our equity securities.

In October 2018, we entered into an “at-the-market” (ATM) sales agreement with Cowen and Company, LLC, or Cowen, pursuant to which we may sell from time to time, ADSs having an aggregate offering price of up to $100.0 million through Cowen, acting as our agent. Sales of our ADSs pursuant to this ATM program are subject to certain conditions specified in the sales agreement. Sales under the ATM program are registered on a shelf registration statement on Form F-3 that we filed with the SEC in October 2018, and which permits the offering, issuance and sale by us of up to a maximum aggregate offering price of $400.0 million of our securities, inclusive of our ADSs sold under the ATM program.

Cash Flows

Comparison of the Three Months Ended March 31, 2021 and March 31, 2020

The following table summarizes the results of our cash flows for the three months ended March 31, 2021 and 2020.

Operating Activities

The net cash used in operating activities was £8.1 million for the three months ended March 31, 2021 as compared to £6.2 million for the three months ended March 31, 2020, a net increase in cash outflows of £1.9 million. Operating loss cash outflows were higher by £2.3 million for the three months ended March 31, 2021, primarily reflecting higher research and development costs. The increase in operating loss cash outflows was offset by working capital inflows of £0.7 million in the three months ended March 31, 2021 as compared to working capital inflows of £0.3 million in the three months ended March 31, 2020.

Investing Activities

The net cash used in investing activities was £0.1 million for the three months ended March 31, 2021 as compared to £0.2 million for the three months ended March 31, 2020. Interest received for the three months ended March 31, 2021 was £24,000 compared with £0.2 million for the three months ended March 31, 2020. In the three months ended March 31, 2021, cash used to acquire intangible assets was lower by £0.3 million than in the three months ended March 31, 2020.

Financing Activities

The net cash from financing activities was £0.1 million for the three months ended March 31, 2021 as compared to net cash used in financing activities of £0.1 million for the three months ended March 31, 2020. In the three months ended March 31, 2021 proceeds from the issue of share capital was £0.2 million. There was no such cash inflow in the three months ended March 31, 2020.

Operating and Capital Expenditure Requirements

We have not achieved profitability on an annual basis since our inception, and we expect to incur net losses in the future. We expect that our operating expenses will increase as we continue to invest in our research and development programs, exploit our ProTide pipeline and build out our organization with additional employees.

We believe that our existing capital resources will be sufficient to fund our operations, including currently anticipated research and development activities and planned capital spending, for at least the next 12 months.

Our future funding requirements will depend on many factors, including but not limited to:

Legal Proceedings

From time to time, we may be party to litigation that arises in the ordinary course of our business. Other than as discussed below, we do not have any pending litigation that, separately or in the aggregate, would, in the opinion of management, have a material adverse effect on our results of operations, financial condition or cash flows.

In 2018, we were granted a European patent from the European Patent Office (EPO), EP 2955190, that covers the composition of matter of a small genus of phosphoramidate nucleotide compounds that includes sofosbuvir, sold under the brand name Sovaldi^®, a leading drug for the treatment of hepatitis C sold by Gilead Sciences, Inc. Sofosbuvir and our drug Acelarin share a similar chemical structure, and sofosbuvir is covered by the claims in our patent, which predates Gilead’s patent on sofosbuvir by several years. Later in 2018, Gilead filed an Opposition to our patent at the EPO in an attempt to revoke it. In February 2021, the EPO Opposition Division disagreed with Gilead and upheld amended patent claims that cover sofosbuvir. We believe this decision is correct, and is a further confirmation of the groundbreaking work of our late Chief Scientific Officer, Professor Christopher McGuigan, as the creator of the ProTide prodrug strategy to deliver nucleotides for the treatment of patients with cancer or viral infections. However, we expect that Gilead will appeal the decision of the Opposition Division to the EPO Technical Boards of Appeal, and there can be no assurance as to the outcome of such an appeal. The Boards of Appeal could disagree with the Opposition Division, in whole or part, and revoke our patent, or agree with the Opposition Division and uphold our patent.

A European patent can be asserted against infringers, in this case Gilead, in national courts in Europe, even before a final decision of the EPO Technical Boards of Appeal, and can also be challenged in national courts. Following the affirmance of our European patent by the EPO Opposition Division, in February 2021, Gilead Sciences, Inc. and Gilead Sciences Limited filed a lawsuit against us in the Patents Court of the High Court of Justice of England and Wales requesting revocation of the UK part of EP 2955190. The lawsuit is proceeding. In March 2021, we filed a counterclaim against Gilead Sciences, Inc. and Gilead Sciences Limited alleging infringement of our patent resulting from acts including the sale of Sovaldi^®, as well as its combination products Harvoni^®, Vosevi^® and Epclusa^®, in the United Kingdom. In April 2021, we initiated legal proceedings against Gilead Sciences Ireland UC and Gilead Sciences GmbH in the German Regional Court of Dusseldorf for patent infringement for the sale of Sovaldi as well as its combination products Harvoni, Vosevi and Epclusa in Germany. We intend to vigorously defend our patent rights and the foundational work of Professor McGuigan.

The appeal of the decision upholding our patent by the EPO Opposition Division, the litigation in the UK Patents Court with Gilead and potential future infringement or validity litigation in Europe with Gilead may subject us to significant legal expense and may be a distraction to management. There can be no assurance that our patent covering sofosbuvir will be upheld as valid and infringed by any national court in Europe, or upheld as valid by the European Technical Boards of Appeal. See “Risk Factors — Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities” in our Annual Report on Form 20-F for the year ended December 31, 2020.

This litigation does not affect the patent protection on any of our product candidates, including Acelarin, which are covered by separate patents that are not involved in this litigation.

Exhibit 99.3

NuCana Reports First Quarter 2021 Financial Results and Provides Business Update

Presented Encouraging Clinical Data at ASCO-GI and AACR

Additional Clinical Data Announcements and Study Initiations Expected in 2021

Edinburgh, United Kingdom, May 19, 2021 (GLOBE NEWSWIRE) – NuCana plc (NASDAQ: NCNA) announced financial results for the first quarter ended March 31, 2021 and provided an update on its broad clinical program with its transformative ProTide therapeutics.

As of March 31, 2021, NuCana had cash and cash equivalents of £78.6 million compared to £87.4 million as of December 31, 2020. NuCana continues to advance its various clinical programs and reported a net loss of £9.8 million for the quarter ended March 31, 2021, as compared to a loss of £4.0 million for the quarter ended March 31, 2020. Basic and diluted loss per share was £0.19 for the quarter ended March 31, 2021, as compared to £0.12 per share for quarter ended March 31, 2020.

“We are very pleased with our momentum in 2021,” said Hugh S. Griffith, NuCana’s Founder and Chief Executive Officer. “In January, we presented data at the American Society of Clinical Oncology Gastrointestinal Cancers Symposium (ASCO-GI) from the NuTide:302 study demonstrating NUC-3373’s encouraging efficacy signals and favorable safety profile in patients with advanced colorectal cancer. Among the efficacy-evaluable population, a disease control rate of 62% was achieved. In addition, NUC-3373 was well tolerated with no hand-foot syndrome or neutropenia as well as lower rates of diarrhea, mucositis and stomatitis as compared to historical data for 5-FU and capecitabine in the frontline treatment of patients with colorectal cancer.”

Mr. Griffith continued: “In April, we were excited to present five posters at the American Association for Cancer Research (AACR) Annual Meeting. NUC-3373 maintained the encouraging 62% disease control rate in the efficacy-evaluable population in the NuTide:302 study. The poster also detailed three patients who experienced reductions in their target lesions of 40%, 28% and 15% and several patients who achieved a longer progression-free survival on NUC-3373 than they had on their prior therapy. We also presented additional clinical data from the ongoing Phase I study of NUC-7738. These data demonstrated NUC-7738’s encouraging anti-cancer activity and favorable tolerability profile. Three case studies described patients who achieved tumor volume reductions and prolonged stable disease on NUC-7738. Other AACR posters showed NUC-3373-treated colon cancer cells are able to activate a natural killer cell response and described how NUC-7738 was designed to overcome the key cancer resistance mechanisms which have prevented the clinical development of its parent nucleoside analog, 3’-deoxyadenosine. Overall, these presentations highlighted the potential of our ProTides to significantly improve the treatment outcomes for patients with cancer.”

Mr. Griffith concluded: “We are excited with the progress we have made so far in 2021. We remain focused on continuing to drive recruitment across all of our ongoing studies, including our Phase III study of Acelarin plus cisplatin in patients with biliary tract cancer as well as initiating new studies, including our second Phase III study evaluating NUC-3373 in combination with other agents for patients with colorectal cancer. We look forward to providing additional updates as we go through 2021.”

Anticipated 2021 Milestones

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, their efficacy is limited by cancer cell resistance mechanisms and they are often poorly tolerated. Utilizing our proprietary technology, we are developing new medicines, ProTides, designed to overcome key cancer resistance mechanisms and generate much higher concentrations of anti-cancer metabolites in cancer cells. NuCana’s robust pipeline includes three ProTides in clinical development. Acelarin and NUC-3373, are new chemical entities derived from the nucleoside analogs gemcitabine and 5-fluorouracil, respectively, two widely used chemotherapy agents. Acelarin is in a Phase III study for patients with advanced biliary tract cancer. NUC-3373 is in a Phase I study for the potential treatment of a wide range of patients with advanced solid tumors and a Phase Ib study for patients with metastatic colorectal cancer. Our third ProTide, NUC-7738, is a transformation of a novel nucleoside analog (3’-deoxyadenosine) and is in a Phase I study for patients with advanced solid tumors.

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 Acelarin, 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, 2020 filed with the Securities and Exchange Commission (“SEC”) on March 4, 2021, 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.

Unaudited Condensed Consolidated Statements of Operations

Unaudited Condensed Consolidated Statements of Financial Position

Unaudited Condensed Consolidated Statements of Cash Flows

For more information, please contact:

NuCana plc

Hugh S. Griffith

Chief Executive Officer

+44 131 357 1111

info@nucana.com

Westwicke, an ICR Company

Chris Brinzey

+1 339-970-2843

chris.brinzey@westwicke.com

RooneyPartners

Marion Janic

+1 212-223-4017

mjanic@rooneyco.com