NUCANA PLC UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS For the Three Months Ended June 30, For the Six Months Ended

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

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

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS

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

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION AS AT

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

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

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

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

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

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 patients with 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 three wholly owned subsidiaries, NuCana, Inc., NuCana Limited 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, 2021 have been reported on by the Company's auditor and delivered to the Registrar of Companies. 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 and six months ended June 30, 2022 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, 2021. No new standards, amendments or interpretations have had an impact on the financial statements for the three months and six months ended June 30, 2022. The financial statements comprise the financial statements of the Group at June 30, 2022. 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, 2021.

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 and six months ended June 30, 2022 are not necessarily indicative of the results that can be expected for the Company's fiscal year ending December 31, 2022.

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 for the 18 month period to December 31, 2023, 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 46.5

million at June 30, 2022 will be sufficient to fund its current operating plan for at least the next 12 months. Further, following the announcement on March 2, 2022 that the Company's Phase 3 clinical trial of Acelarin for patients with advanced biliary tract cancer was being discontinued, the directors have concluded that this will have a positive impact on the cash outflows of the Company over the period assessed for going concern purposes.

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.

The Company continues to evaluate and assess the impact of COVID-19

on its operations and believes that this pandemic will potentially cause some delays to the timing and progress of its clinical trials.

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, 2021.

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

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 2.4 million as of June 30, 2022 (as of December 31, 2021: 2.3 million) and computer software with a carrying value of 0.1 million as of June 30, 2022 (as of December 31, 2021: 0.1 million).

During the six months ended June 30, 2022, the Company acquired intangible assets with a cost of 0.3 million in relation to patents.

6. Other non-current

During 2021, the Company provided a security of 3.0 million by depositing the funds with the German Regional Court of Dusseldorf ("RC Dusseldorf") to cover the legal costs of Gilead Sciences Ireland UC and Gilead Sciences GmbH in the event that the Company is unsuccessful in the final outcome of the patent infringement litigation in Germany.

The extent to which the sum deposited will be reimbursed to the Company is dependent on a range of potential outcomes, and the timing of those outcomes, with respect to the patent infringement litigation in Germany, which is currently indeterminable.

7. Cash and cash equivalents

Cash and cash equivalents comprise cash at banks with deposit maturity terms of three months or less. Cash at banks earns interest at fixed or variable rates based on the terms agreed for each account.

8. 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. 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. Options granted under each of the six plans have a maximum life of 10 years.

As detailed in the table below, during the six months ended June 30, 2022, 1,115,925 share options were granted under the 2020 Long-Term Incentive Plan (six months ended June 30, 2021: 1,501,663 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.

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 four 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 four years or less, have been valued using the Company's own historical volatility rates.

For the three months ended June 30, 2022, the Company recognized 1.2 million of share-based payment expense in the statement of operations (three months ended June 30, 2021: 1.8 million). For the six months ended June 30, 2022, the Company recognized 2.7 million of share-based payment expense in the statement of operations (six months ended June 30, 2021: 3.6 million).

9. Share capital and share premium

10. 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 (15.05% at June 30, 2022). Based on the closing price of the Company's ADSs on the Nasdaq Global Select Market on June 30, 2022, 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 0.2 million (December 31, 2021: 0.4 million).

As referenced in Note 6, during 2021 the Company provided a security of 3.0 million to cover the legal costs of Gilead Sciences Ireland UC and Gilead Sciences GmbH in the event that the Company is unsuccessful in the final outcome of the patent infringement litigation in Germany. Any cost reimbursement by the Company to the defendants is dependent on a range of potential outcomes, and the timing of those outcomes, with respect to the litigation, which are currently indeterminable. Therefore, no provision has been recognized with respect to these legal costs as the Company does not consider it probable that the litigation will be unsuccessful.

11. Events after the reporting period

In July 2022, following a comprehensive hearing in May 2022, RC Dusseldorf issued a first instance judgment that the two Gilead entities infringe our composition of matter claims in EP 2955190 through their sales of Sovaldi, Harvoni, Vosevi and Epclusa in Germany. Following this judgment, Gilead is obliged to bear the costs of these proceedings, including approximately

0.9 million ( 0.8 million) of costs incurred to date by NuCana in relation to the patent infringement litigation in Germany. The precise amount is to be fixed by the RC Dusseldorf and Gilead

the judgment. Any such cost reimbursement by Gilead to the Company is dependent on the final outcome of the proceedings and other factors, the timing and certainty of which are currently indeterminable.