Financial review

Selected highlights of the Group's financial results are as follows:

•   Total revenues in H1 2025 increased by 44% to £73.2 million (£73.4 million constant currency) (H1 2024:

£50.8 million), demonstrating continued momentum following the revenue growth in 2024.

•   The strong revenue growth was driven by:

-  Continued strong lentiviral vector manufacturing of GMP batches for clients both in the clinical and commercial launch phases

-  Clients progressing their clinical development, including an increase in development revenues from process characterisation and validation work

-  Procurement and Storage services, which is a new revenue stream since H2 2024, to provide stability of supply of raw materials for clients undergoing commercial preparation activities.

•   Significant improvement in profitability, with Operating EBITDA loss of £(8.3) million (£(3.9) million constant currency) (H1 2024: £(20.3) million loss) driven by the stronger revenues building on the growing momentum seen in H2 2024.

•   Operating loss of £(23.6) million also represented a significant decrease compared with H1 2024

(£(32.2) million) due to a combination of increased revenues and focus on managing the overall cost base to drive the Group towards profitability.

•   Reduced cash outflow to £(4.8) million (H1 2024: £(48.6) million) arising principally from operating loss improvement, disciplined cash control and enhanced working capital management via receipt of deposits and upfront payments from clients.

•   Cash at 30 June 2025 was £53.9 million (31 December 2024: £60.7 million); net cash at 30 June 2025 was

£17.1 million (31 December 2024: £20.6 million). Post-period end, cash at 31 August 2025 was £113.7 million.

•   Following the exercise of the Call Option in March 2025, OXB completed the acquisition of the remaining 10% stake in its US subsidiary, OXB US LLC, from Q32 Bio, Inc., in June 2025, bringing its ownership to 100%

as planned.

•   Post-period, in August 2025, the Group entered into a new four-year term loan facility of up to $125 million with Oaktree Capital Management, L.P. ("Oaktree"), drawing $60 million (£45.3 million) on completion to refinance the existing $50 million (£37.8 million) facility.

•   In August 2025, the Group completed a placing of new shares, raising c.£60 million gross proceeds to strengthen OXB's global CDMO network, including expansion of US commercial-scale GMP capacity and to advance process quality, productivity and yields in response to increased client demand.

Key financial performance indicators

The Group evaluates its performance inter aliaby making use of alternative performance measures as part of its Key Financial Performance Indicators (refer to the table below). The Group believes that these Non-GAAP measures, together with the relevant GAAP measures, provide a comprehensive, accurate reflection of the

Group's performance over time. The Board has taken the decision that the Key Financial Performance Indicators against which the business will be assessed are Revenue, Operating EBITDA and Operating (loss). The figures presented in this section for prior years are those reported in the Interim Reports for those years.

Cash Flow

1 Operating EBITDA (Earnings Before Interest, Tax, Depreciation, Amortisation, revaluation of investments and assets at fair value through profit and loss, and share based payments) is a non-GAAP measure often used as a surrogate for operational cash flow as it excludes from operating profit or loss all non-cash items, including the charge for share based payments. However, deferred bonus share option charges are not added back to operating profits in the determination of Operating EBITDA as they may be paid in cash upon the instruction of the Remuneration Committee. A reconciliation to GAAP measures is provided on page 12.

2 This is purchases of property, plant and equipment as per the cash flow statement which excludes additions to right-of-use assets.

3 Net cash (outflow) is net cash consumed from operations plus net interest plus capital expenditure. A reconciliation to GAAP measures is provided on page 13.

Revenue

Group revenue of £73.2 million represented a 44% increase on H1 2024 (£50.8 million).

Revenue generated from manufacturing services increased by 25% to £34.4 million (H1 2024: £27.6 million) due to an increase in the number of batches manufactured for clinical clients and for clients in preparation for commercial launch.

Revenue generated from development services increased by 48% to £28.5 million (H1 2024: £19.3 million) due to client products progressing their clinical development, including an increase in development revenues from process characterisation and validation work. Refer to Note 4 for further details on client concentration.

Procurement and storage services generated £8.6 million in revenue (H1 2024: £ nil). This revenue line, recognised as point in time, represents additional procurement and storage services, representing OXB's readiness to provide clients stability of supply and the maturity of the Group in its capacity as a CDMO.

Revenues from licence fees, milestones and royalties decreased by 56% to £1.7 million (H1 2024: £3.9 million). There were no milestones in this period (H1 2024: £2.1 million) which is due to the timing of milestones achieved from existing clients. Licences of £0.4 million (H1 2024: £nil) were received in the period. Royalties decreased to

£1.3 million (H1 2024: £1.8 million) as the Kymriah product matures through its life cycle.

Gross Margin in 2025 was 43% (H1 2024: 35%) due to product and client mix which create variability in gross margins across comparative periods and the positive impact of a client paying cancellation fees in the period.

Operating EBITDA

1 CC refers to constant currency which refers to the equivalent values based on the prior year exchange rates.

2 Total EBITDA related expenses are operational expenses including cost of goods incurred by the Group. A reconciliation to GAAP measures is provided on page 11.

3 Operating EBITDA (Earnings Before Interest, Tax, Depreciation, Amortisation, revaluation of investments and assets at fair value through profit and loss, and share based payments) is a non-GAAP measure often used as a surrogate for operational cash flow as it excludes from operating profit or loss all non-cash items, including the charge for share based payments. However, deferred bonus share option charges are not added back to operating profits in the determination of Operating EBITDA as they may be paid in cash upon the instruction of the Remuneration Committee. A reconciliation to GAAP measures is provided on page 12.

4 Non-cash items include depreciation, amortisation, revaluation of investments, fair value adjustments of available-for-sale assets and the share based payment charge.

OXB reported operating EBITDA loss of £(8.3) million (£(3.9) million constant currency), (H1 2024: £(20.3) million) and operating loss of £(23.6) million (H1 2024: £(32.2) million). The EBITDA improvement is driven by revenue growth of 44% combined with judicious management of the cost base increasing by 10% to £82.1 million (H1 2024:

£74.4 million). The individual cost areas are explained in more detail in the Total Expenses section below.

Other operating income includes sublease rental income of £0.3 million (H1 2024: £1.2 million), which has reduced due to the end of the sublease with Q32 Bio, Inc (formerly Homology Medicines, Inc) at the Bedford MA site and grant income to further develop supply chain capabilities of £0.3 million (H1 2024: £0.3 million). In H1 2024 the Group also benefited from a one-off £1.7 million gain related to the acquisition of OXB France.

Total Expenses

The Group has removed, from Operating Expenses, depreciation, amortisation and the share option charge as these are non-cash items and do not form part of the Operating EBITDA alternative performance measure.

As Operating (loss) is assessed separately as a key financial performance measure, the year-on-year movement in these non-cash items is then individually analysed and explained specifically in the Operating and Net

(loss) section.

1 Operational, commercial, innovation and administrative expenses excluding depreciation, amortisation and the share option charge.

2 Total EBITDA related expenses are operational expenses including cost of goods incurred by the Group. A reconciliation to GAAP measures is provided on page 11.

In order to provide the users of the accounts with a more detailed explanation of the reasons for the year-on-year movements of the Group's Total Expenses, the Group has categorised according to their relevant nature with the year-on-year movement in the tables below.

1 Includes the RDEC tax credit.

1 Includes the RDEC tax credit.

Total EBITDA related expenses increased by £7.7 million to £82.1 million (H1 2024: £74.4 million), including 27% increase in cost of sales to £41.6 million (H1 2024: £32.9 million) supporting the 44% increase of revenue.

The decrease in Adjusted Operating expenses by 3% to £40.5 million (H1 2024: £41.6 million), is a result of the Group's focus on profitability as this includes an additional month of the French entity against comparatives.

•   Cost of sales is the costs directly associated with delivering revenue. Of this, 55% is raw materials and 45% is absorbed operational costs. As the business continues to expand, the cost of sales element of total expenses is expected to grow in line with revenues.

•   Operating costs have decreased to £30.3 million (H1 2024: £33.9 million), reflecting the increased utilisation of the Group's cost base as it operates at higher output levels delivering more batches for clients.

•   Innovation costs have decreased to £2.0 million (H1 2024: £2.3 million), as the Group continues to invest in the lentiviral vector platform, driving innovation for its clients to increase yields.

•   Administration costs have increased to £20.6 million (H1 2024: £14.4 million), primarily driven by the impact of the loss on foreign exchange of £4.2 million related to the unrealised translation of USD denominated balances and the full six months of the larger Group (post-acquisition of OXB France), changes in Group management and cost inflation.

Review of Expenses by Type

•   Raw materials and external costs have increased by 18% as a direct result of the increase in the number of lentiviral vector batches produced and development activities. 95% of these costs are classified as cost of sales and increase with revenue.

•   Manpower-related costs have increased by 2% partly related to the increase in headcount to support the higher revenue base and the full six months of OXB France.

•   Site costs have decreased by 10% and include impact of absorption of facility costs (rent, utilities and maintenance)

•   Corporate costs have increased by £4.2 million primarily driven by the impact of a loss on foreign exchange and increased corporate support for the growing business, the impact of the inclusion of the additional month of expenditure of OXB France and inflationary increases.

•   The RDEC credit has increased to £3.0 million (H1 2024: £2.9 million) due to an increase in activity which qualifies for supporting the resolution of scientific uncertainty and is shown within the Corporate costs.

Operating (loss) and net (loss)

1   Operating EBITDA (Earnings Before Interest, Tax, Depreciation, Amortisation, revaluation of investments and assets at fair value through profit and loss, and share based payments) is a non-GAAP measure often used as a surrogate for operational cash flow as it excludes from operating profit or loss all non-cash items, including the charge for share based payments. However, deferred bonus share option charges are not added back to operating profits in the determination of Operating EBITDA as they may be paid in cash upon the instruction of the Remuneration Committee.

In arriving at Operating (loss) it is necessary to deduct from Operating EBITDA the non-cash items referred to above. The depreciation amounts to £11.9 million (H1 2024: £10.2 million) and amortisation £1.2 million (H1 2024:

£1.3 million). The share option charge in the period is £2.1 million (H1 2024: £0.4 million).

The impact of these charges resulted in H1 2025 operating loss of £(23.6) million compared to H1 2024 loss of

£(32.2) million in the prior year.

H1 2025 net interest and foreign exchange charge decreased by £1.0 million as result of £3.4 million foreign exchange gain in respect of the Oaktree loan replacing losses (£(0.4) million) in 2024. In addition, lower group cash balances reduced interest received by (£0.7 million) and interest paid on finance leases increased by

£2.1 million as a result of the conclusion of the Oxbox rent review and the full 6 months impact of the acquisition of OXB France.

Other Comprehensive Income

The Group recognised a loss within other comprehensive income in H1 2025 of £(5.0) million (H1 2024:

£(0.2) million) in relation to movements on the foreign currency translation reserve.

The translation reserve comprises all foreign currency differences arising from the translation of the financial statements of foreign operations, including gains arising from monetary items that in substance form part of the net investment in foreign operations.

Cash flow

1   Depreciation, Amortisation, revaluation of investments and assets at fair value through profit and loss, and share based payments.

2   Operating EBITDA (Earnings Before Interest, Tax, Depreciation, Amortisation, Impairment, revaluation of investments and assets at fair value through profit and loss, and share based payments) is a non-GAAP measure often used as a surrogate for operational cash flow as it excludes from operating profit or loss all non-cash items, including the charge for share based payments. However, deferred bonus share option charges are not added back to operating profits in the determination of Operating EBITDA as they may be paid in cash upon the instruction of the Remuneration Committee. A reconciliation to GAAP measures is provided on page 12.

3   This is Changes in working capital as laid out in: Cash flow from operating activities on page 31.

4   This is Purchases of property, plant and equipment as per the cash flow statement which excludes additions to Right-of-use assets.

5   Net cash (outflow) is net cash consumed from operations plus net interest plus capital expenditure.

The Group held £53.9 million of cash at 30 June 2025 (31 December 2024: £60.7 million). Significant movements across the year, are explained below:

•   The operating EBITDA loss of £(8.3) million (£(3.9) million constant currency).

•   A positive working capital movement of £6.8 million principally driven by:

-  An increase in Trade and other receivables of (£9.3) million to £67.2 million

-  A decrease in Trade and other payables of (£3.9) million to £22.3 million; and

-  An increase in Contract Liabilities and Deferred Income of £22.2 million to £47.4 million. This increase is driven by a £20 million uplift in the value of deposits for late-stage and commercial manufacturing in 2026 to

£33.7 million.

-  An increase in inventories of (£2.0) million as a result of increased upcoming manufacturing.

•   The 2023 UK RDEC refund £5.1 million from HMRC was received in March 2025 (H1 2024: nil).

•   Purchases of property, plant and equipment of £1.5 million (2024: £4.8 million), as the Group completed investment in the expansion of lentiviral development and manufacturing capabilities to the sites in the US and France as part of the execution of its "One OXB" strategy which started in 2024.

•   Lease payments of £5.6 million (2024: £5.0 million) for all facilities which have increased due to updated rent review on the Oxbox site and an additional month of leases related to OXB France.

The result of the above movements is a net decrease of £6.8 million which leads to a decrease in cash from

£60.7 million to £53.9 million.

Financial Outlook

1Excludes the impact of FX fluctuations

Financial guidance for 2025 and capital expenditure expectations remain unchanged, with the Group expecting revenue of £160-170 million (on a constant currency basis) and operating EBITDA profitability in the low single- digit £ millions (on a constant currency basis).

The Group's revenue backlog¹ stood at approximately £222 million as at 30 June 2025 compared to £150 million as at 31 December 2024. This is the amount of future revenue available to earn from current orders.

£171 million of 2025 revenues are covered by contracted client orders, compared to £106 million for the same period last year. This provides clear visibility for the remainder of the year (subject to revenue performance obligations), with revenues weighted to H2, in line with prior years. H2 revenue phasing includes an increase in manufacturing activity for clients preparing for commercial launch.

Post-period end, the Group strengthened its balance sheet with a c.£60 million placing of new shares. Proceeds from the placing will support planned strategic investments to strengthen the Group's global CDMO network, and is expected to accelerate revenue and margin growth.

These strategic investments are expected to be revenue accretive from FY 2026, supporting 25-30% year-on- year revenue growth in 2027 and 2028, ahead of the broader market². FY 2026 revenues are expected to be between £220-240 million, representing 35-39% CAGR for 2023-2026.

With 2,210 cell and gene therapies in the clinical pipeline worldwide - up from 2,068 in Q2 2024³, the Group remains confident in the cell and gene sector's strong fundamentals. OXB's expected strong revenue trajectory is underpinned by growth of pre-clinical and early-stage clinical programmes, as well as continued advancement of late-stage programmes among the Group's clients, which have included recent regulatory milestones and

positive clinical data readouts. Together, these factors are expected to contribute to above-market growth, stronger profitability and an increased share of the viral vector market.

1 Revenue backlog represents the ordered gross value of CDMO revenues available to earn. The value of customer orders included in revenue backlog only includes the value of work for which the customer has signed a financial commitment for OXB to undertake, whereby any changes to agreed values will be subject to change orders, cancellation fees or the triggering of optional/contingent contractual clauses.

2 Source: GlobalData and company estimates, cell and gene therapy market for CDMOs forecasted to grow at 20% in 2027 and 17% in 2028.

3 Source: American Society of Gene & Cell Therapy (ASGCT) & Citeline, Q2 2025 Gene, Cell & RNA Therapy Landscape Report, August 2025.

Management will continue to drive cost discipline. Operating expense increases associated with strategic investments and increased capacity are limited and time-bound to qualification and ramp activities, with a focus on margin expansion as utilisation builds.

Including the additional investment, operating EBITDA margin is expected to exceed 10% in FY 2026 and be at least 20% for FY 2027, with long-term potential to approach c.30% (within a five-to-six year time period) as expanded capacity, particularly in the US, is utilised.

Capital expenditure, including strategic investments for future growth, is expected to be

approximately £60 million in the aggregate for 2026 and 2027, split broadly evenly between the two years, with steady state capex of approximately £20-25 million per year thereafter.

Principal risks and uncertainties

Risk assessment and evaluation is an integral and well-established part of the Group's management processes. During the first six months of the financial year, the Group has continued to implement targeted mitigation strategies, each designed to address specific risks effectively.

OXB continues to monitor its going concern position, as set-out on page 23. The Group remains alert to the continuing emerging risks relating to geopolitics, cyber, legal, regulatory and compliance. As outlined above, OXB continues to implement proactive strategies to manage and mitigate these evolving risk exposures.

Details of the Group's principal risks and uncertainties can be found on pages 59 to 63 of the 2024 Annual Report and Accounts which is available on the Group's website at www.oxb.com. The risks associated with "Failure to execute strategic transition" and "Vector strategy", as disclosed in 2024 Annual Report and Accounts have been effectively mitigated.

Commercialisation risks

•   Failure to execute partner collaborations

•   Rapid technological change

Supply chain and business execution risks

•   Third party suppliers and supply chain

•   Manufacturing failure

•   Failure in information technology or cyber security

•   Failure to attract, develop, engage and retain a diverse, talented and capable workforce

Legal, regulatory and compliance risks

•   Adverse outcome of litigation and/or governmental investigations

Economic and financial risks

•   Foreign currency exposure and loan facility

•   Geopolitical Risks

Climate Risk

OXB recognises climate-related risks as a material factor in its business planning and strategy. These risks include:

•   Physical risks arising from extreme weather events or long-term changes in climate that could affect operations, facilities and supply chains.

•   Transition risks associated with regulatory changes, market shifts and technological developments as the global economy moves toward a low-carbon model.

•   Operational and financial implications, including impacts on energy use, emissions management, water and waste baselining, and compliance with evolving climate-related regulations.

OXB's governance framework, in line with TCFD recommendations, ensures these risks are identified, monitored and managed across all sites, with oversight from the Board, ESGR Committees and the Net Zero Group.

Going concern

The financial position of the Group, its cash flows and liquidity position are described in the Financial Statements and notes to these financial statements section of these accounts.

The Group made a loss after tax for the 6-month period ended 30 June 2025 of £(26.9) million (H1 2024:

£(36.4) million) and consumed net cash flows from operating activities for the period of £(1.5) million. The Group ended the period with cash and cash equivalents of £53.9 million (31 December 2024: £60.7 million).

In considering the basis of preparation of the H1 2025 Report and half-year accounts, the Directors have prepared cash flow forecasts for a period of 15 months from the date of approval of these financial statements, based on the Group's 2025 latest forecast and forecasts for 2026. The Directors have undertaken a rigorous assessment of the forecasts in a base case scenario and assessed identified downside risks and mitigating actions. These cash flow forecasts also take into consideration severe but plausible downside scenarios including:

•   Commercial challenges leading to a substantial manufacturing and development revenue downside affecting both the LentiVector® platform and AAV businesses;

•   Considerable reduction in revenues from new clients;

•   Removal of any future licence revenues; and

•   The potential impacts of a downturn in the biotechnology sector on the Group and its clients including expected revenues from existing clients under long term arrangements.

Under both the base case and mitigated downside scenario, the Group and Company have sufficient cash resources to continue in operation for a period of at least 12 months from the date of approval of these financial statements.

In the event of all the downside scenarios above crystallising, the Group and Company would continue to comply with its existing loan covenants beyond December 2026 without taking any mitigating actions, but the Board has mitigating actions in place that are largely within its control that would enable the Group to reduce its spend within a reasonably short time-frame to increase the Group and Company's cash covenant headroom as required by the loan facility with Oaktree Capital Management. Specifically, the Group will continue to monitor its performance against the base case scenario and if base case cash-flows do not crystallise, start taking mitigating actions

by the end of Q4 2025 which may include reduction in investments, rationalisation of facilities and rightsizing the workforce.

In addition, the Board has confidence in the Group and Company's ability to continue as a going concern for the following reasons:

•   As noted above, the Group has cash balances of £53.9 million at the end of June 2025;

•   £171 million of 2025 forecasted revenues are covered by contracted client orders which give confidence in the level of revenues forecast over the next 6 months;

•   The Group has refinanced its existing credit facility, which was due for repayment in October 2026, with a new loan repayable in June 2029;

•   In August 2025, the Group has successfully completed placement of new ordinary shares raising gross proceeds of approximately £60 million;

•   The Group's ability to continue to be successful in winning new clients and building its brand as demonstrated by successfully entering into new client agreements over the last 6 months; and

•   The Group has the ability to control capital expenditure costs and lower other operational spend, as necessary.

Taking account of the matters described above, the Directors are confident that the Group and Company will have sufficient funds to continue to meet their liabilities as they fall due for at least 12 months from the date of approval of the financial statements and therefore have prepared the financial statements on a going concern basis.

Lucinda Crabtree

Chief Financial Officer