NORTHWEST BIOTHERAPEUTICS INC

1. Organization and Description of Business

Northwest Biotherapeutics, Inc. and its wholly owned subsidiaries Flaskworks, Northwest Biotherapeutics Limited (formerly known as Aracaris Ltd), Northwest Biotherapeutics Capital Limited (formerly known as Aracaris Capital Limited), Northwest Biotherapeutics B.V., NW Bio GmbH, Advent BioServices Ltd. (“Advent”) (collectively, the “Company”, “we”, “us” and “our”) were organized to discover and develop innovative immunotherapies for cancer. The Company has developed DCVax® platform technologies for both operable and inoperable solid tumor cancers. The Company has wholly owned subsidiaries in Boston, the U.K., the Netherlands and Germany.

The Company’s subsidiaries include Advent BioServices, which provides product and process development services, manufacturing, controlled storage and distribution services for the Company’s DCVax products. The Company acquired Advent on October 24, 2025, as previously reported. Advent was founded in 2016 and is based in Sawston (Cambridge) in the U.K.

The Company has completed a Phase 3 clinical trial of its DCVax®-L product for glioblastoma brain cancer, has publicly reported the results in a peer reviewed publication in a medical journal as well as at a medical conference, and submitted a Marketing Authorization Application (MAA) for regulatory approval by the Medicines and Healthcare Products Regulatory Agency (MHRA) in the U.K. in December 2023. The MAA is in the process of undergoing MHRA review.

2. Financial Condition, Going Concern and Management Plans

The Company has incurred annual net operating losses since its inception. The Company had a net loss of $3.1 million for the three months ended March 31, 2026.

The Company does not expect to generate material revenue in the near future from the sale of products and is subject to all of the risks and uncertainties that are typically faced by biotechnology companies that devote substantially all of their efforts to research and development (“R&D”) and clinical trials and do not yet have commercial products. The Company expects to continue incurring annual losses for the foreseeable future. The Company’s existing liquidity is not sufficient to fund its operations, anticipated capital expenditures, working capital and other financing requirements until the Company reaches significant revenues. Until that time, the Company will need to obtain additional equity and/or debt financing, especially if the Company experiences downturns in its business that are more severe or longer than anticipated, or if the Company experiences significant increases in expense levels resulting from being a publicly-traded company or from expansion of operations. If the Company attempts to obtain additional equity or debt financing, the Company cannot assume that such financing will be available to the Company on favorable terms, or at all.

Because of recurring operating losses and operating cash flow deficits, there is substantial doubt about the Company’s ability to continue as a going concern for at least one year from the date of this filing. The consolidated financial statements have been prepared assuming that the Company will continue as a going concern, however, they do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets, or the amounts and classification of liabilities that may result from the outcome of this uncertainty.

3. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated interim financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated. Certain immaterial reclassifications have been made to prior period amounts to conform to the current period presentation.

The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with the accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and pursuant to the instructions to Form 10-Q and Article 8 of Regulation S-X of the Securities and Exchange Commission (“SEC”) and on the same basis as the Company uses to prepare its annual audited consolidated financial statements. The condensed consolidated balance sheet as of March 31, 2026, condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2026 and 2025, condensed consolidated statement of stockholders’ deficit for the three months ended March 31, 2026 and 2025, and the

condensed consolidated statements of cash flows for the three months ended March 31, 2026 and 2025 are unaudited, but include all adjustments, consisting only of normal recurring adjustments, which the Company considers necessary for a fair presentation of the financial position, operating results and cash flows for the periods presented. The results for the three months ended March 31, 2026 are not necessarily indicative of results to be expected for the year ending December 31, 2025 or for any future interim period. The condensed consolidated balance sheet at December 31, 2025 has been derived from audited financial statements; however, it does not include all of the information and notes required by U.S. GAAP for complete financial statements. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements for the year ended December 31, 2025 and notes thereto included in the Company’s annual report on Form 10-K (the “2025 Annual Report”), which was filed with the SEC on April 15, 2026.

Use of Estimates

In preparing condensed consolidated financial statements in conformity with U.S. GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates.

On an ongoing basis, the Company evaluates its estimates and judgments, including valuing equity securities in share-based payment arrangements, estimating the fair value of financial instruments recorded as derivative liabilities, useful lives of depreciable assets, and whether impairment charges may apply. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the reported amounts of revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates.

Segment Information

The Company operates inone operating segment for the purposes of assessing performance, making operating decisions, and allocating Company resources. The Company’s chief operating decision maker (CODM) is its chief executive officer, who considers net loss to evaluate overall expenses associated with conducting research and development activities, which includes evaluating the progress of ongoing clinical trials and the planning and execution of current and future research and development activities. Further, the CODM reviews and utilizes functional expenses (research and development and general and administrative) as reported in the consolidated statements of operations to manage the Company’s operations. The measure of performance, significant expenses, and other items are each reflected in the consolidated statements of operations. The accounting policies of the Company’s single reportable segment are the same as those for the consolidated financial statements. The level of disaggregation and amounts of significant segment expenses that are regularly provided to the CODM are the same as those presented in the consolidated statements of operations. The measure of segment assets is reported on the consolidated balance sheets as total assets.

Significant Accounting Policies

There have been no material changes in the Company’s significant accounting policies from those previously disclosed in the 2025 Annual Report.

Recently Adopted Accounting Standards

In November 2024, the FASB issued ASU 2024-04, Debt-Debt with Conversion and Other Options (Subtopic 470-20): Induced Conversions of Convertible Debt Instruments. This standard clarifies the requirements for determining whether certain settlements of convertible debt instruments should be accounted for as an induced conversion and the application of the induced conversion guidance to a conversion debt instrument. It also clarifies that the incorporation, elimination, or modification of a daily volume-weighted average price (“VWAP”) formula does not automatically cause a settlement to be accounted for as an extinguishment. This standard will become effective on a prospective or retrospective basis for interim reporting periods and annual periods beginning after December 15, 2025. Early adoption is permitted. The Company adopted this guidance effective January 1, 2026 on a prospective basis. The adoption of this standard did not have a material impact on the Company’s financial position, results of operations, or cash flows.

Recently Issued Accounting Standards Not Yet Adopted

In November 2024, the FASB issued ASU No. 2024-03 (“ASU 2024-03”), Disaggregation of Income Statement Expenses (DISE) which requires disaggregated disclosure of income statement expenses for public business entities. The standard requires public business entities to disclose disaggregated information about specific natural expense categories underlying certain income statement expense line items that are considered relevant. The FASB also issued ASU No. 2025-01 (“ASU 2025-01”), Clarifying the Effective Date, which clarifies the adoption date of ASU 2024-03 as annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027. The Company is currently evaluating the potential effect of this accounting standard update on its consolidated financial statements and related disclosures.

In September 2025, the FASB issued ASU No. 2025 - 06, Intangibles - Goodwill and Other - Internal - Use Software (“ASU 2025 – 06”), which amends the guidance for accounting for software costs to reflect current software development practices, including iterative and agile methodologies, by removing references to development stages. It also clarifies the criteria for capitalization, which begins when both of the following occur: (1) management has authorized and committed to funding the software project and (2) it is probable that the project will be completed and the software will be used to perform the function intended. ASU 2025 - 06 is effective for fiscal years beginning after December 15, 2027, and interim periods within those fiscal years. Early adoption is permitted. The amendments may be applied either prospectively, retrospectively, or utilizing a modified transition approach. The Company is currently assessing the impact of ASU 2025 - 06 on its condensed consolidated financial statements and disclosures.

In September 2025, the FASB issued ASU 2025-07. This update clarifies the application of derivative accounting to certain contracts and refines the guidance for share-based noncash consideration received from customers. Specifically, ASU 2025-07 introduces a scope exception for contracts that are not exchange-traded and whose underlying is tied to operations or activities specific to one party. It also clarifies that share-based noncash consideration from a customer should initially be accounted for under Topic 606 until the right to receive or retain such consideration becomes unconditional, at which point financial instruments guidance may apply. The effective date for the standard is for fiscal years beginning after December 15, 2026 and interim periods within those fiscal years. Early adoption is permitted. The amendments in ASU 2025-07 should be applied either prospectively or by utilizing a modified retrospective approach. The Company is currently assessing the impact on its condensed consolidated financial statements and disclosures.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements. This update clarifies interim disclosure requirements and centralizes such requirements within Topic 270. Among other changes, ASU 2025-11 introduces a disclosure principle requiring entities to provide information about significant events or changes since the end of the last annual reporting period that have a material impact, clarifies when duplicative annual disclosures may be omitted from interim reports, and aligns interim reporting requirements with applicable SEC guidance for registrants. This guidance is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted. The amendments in ASU 2025-11 should be applied prospectively. The Company is currently assessing the impact on its condensed consolidated financial statements and disclosures.

In December 2025, the FASB issued ASU 2025-12, Codification Improvements. This update addresses shareholder suggestions on the Accounting Standards Codification and makes other incremental improvements to U.S. GAAP. The amendments make codification updates to a broad range of topics arising from technical corrections, unintended application of the codification, clarifications and other minor improvements. This guidance is effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods within those annual periods. Early adoption is permitted and may be elected on an issue-by-issue basis. The amendments in ASU 2025-12 are to be applied prospectively. The Company is currently assessing the impact on its condensed consolidated financial statements and disclosures.

4. Fair Value Measurements

In accordance with ASC 820 (Fair Value Measurements and Disclosures), the Company uses various inputs to measure the fair value of liabilities related to certain embedded conversion feature associated with its warrant liability, convertible debt, share payable, and contingent payable to Cognate BioServices on a recurring basis to determine the fair value of these liabilities. The Company has also elected the fair value option (the “FVO”) for certain financial instruments, such as convertible notes.

ASC 820 establishes a hierarchy categorizing inputs into three levels used to measure and disclose fair value. The hierarchy gives the highest priority to quoted prices available in active markets and the lowest priority to unobservable inputs. An explanation of each level in the hierarchy is described below:

Level 1 - Unadjusted quoted prices in active markets for identical instruments that are accessible by the Company on the measurement date.

Level 2 - Quoted prices in markets that are not active or inputs which are either directly or indirectly observable.

Level 3 - Unobservable inputs for the instrument requiring the development of assumptions by the Company.

The following table classifies the Company’s liabilities measured at fair value on a recurring basis into the fair value hierarchy as of March 31, 2026 and December 31, 2025 (in thousands):

There wereno transfers between Level 1, 2 or 3 during the three-month period ended March 31, 2026.

The following table presents changes in Level 3 liabilities measured at fair value for thethree-month period ended March 31, 2026. Both observable and unobservable inputs were used to determine the fair value of positions that the Company has classified within the Level 3 category. Unrealized gains and losses associated with liabilities within the Level 3 category include changes in fair value that were attributable to both observable (e.g., changes in market interest rates) and unobservable (e.g., changes in unobservable long- dated volatilities) inputs (in thousands).

A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring the Company’s share payable that are categorized within Level 3 of the fair value hierarchy as of March 31, 2026 and December 31, 2025 is as follows. The liability relates to the remaining redemption feature which, like the convertible notes at fair value, includes discount factors that are unobservable inputs and proprietary in nature.

5. Stock-based Compensation

The following table summarizes total stock-based compensation expense for the three months ended March 31, 2026 and 2025 (in thousands). The research and development expense during the three months ended March 31, 2026 and 2025 were related to the ongoing vesting of stock option awards previously granted to Flaskworks employees, Scientific Advisory Board members, and external consultants. The 2026 expenses were related to the portion of awards vesting during the period that were granted in early 2026 and between 2020 and 2023. The 2025 expenses related entirely to the portion of awards vesting during that period that were granted between 2020 and 2023.

The total unrecognized stock compensation cost (primarily for consultants) was approximately $0.8 million as of March 31, 2026 and will be recognized over the next 1.8 years.

Stock Options

The following table summarizes stock option activity during the three months ended March 31, 2026 (amount in thousands, except per share number):

The Black-Scholes option pricing model is used to estimate the fair value of stock options granted. The weighted average assumptions used in calculating the fair values of stock options that were granted during the three months ended March 31, 2026 and 2025:

6. Intangible Assets, Net

Intangible assets as of March 31, 2026 and December 31, 2025 consisted of the following (in thousands):

The amortization expense related to the finite-lived intangibles was approximately $0.2 million for the three months ended March 31, 2026.

As of March 31, 2026, the Company’s estimate of amortization for finite-lived intangibles for each of the five succeeding fiscal years and thereafter was as follows:

7. Property, Plant and Equipment

Property, plant and equipment consist of the following at March 31, 2026 and December 31, 2025 (in thousands):

Depreciation expense was approximately $0.6 million and $0.4 million for the three months ended March 31, 2026, and 2025, respectively.

8. Outstanding Debt

The following two tables summarize outstanding debt as of March 31, 2026 and December 31, 2025, respectively (amount in thousands, except per share amounts):

Notes Payable

During the three months ended March 31, 2026, the Company issued approximately 20.9 million shares of common stock with a fair value of $5.2 million to certain lenders in lieu of cash payments of $4.0 million of debt, including $0.8 million of accrued interest. In addition, the Company has extinguished certain debt pursuant to exchange agreements executed with various holders pursuant to which the Company issues common stock at a price based on a limited pricing period (the “Share payable”). During the three months ended March 31, 2026, the Company settled $0.2 million of Share payables and accrued $0.3 million of Share payables. The Company recognized an approximately $1.3 million debt extinguishment loss during the three months ended March 31, 2026 from the debt redemption.

Convertible Notes

During the three months ended March 31, 2026, the Company entered into aone-year convertible note and severaltwo-year convertible notes (collectively the “Convertible Notes”) with multiple individual investors (the “Holders”) with an aggregate principal amount of $1.5 million. The Convertible Notes bear interest at 11% per annum and are convertible into common shares between $0.21 and $0.23 per share at the Holders’ option.

During the three months ended March 31, 2026, the Company modified a convertible note that was originally issued in February 2024 by extending the maturity date. The modification was accounted for as a debt extinguishment. As a result, the Company recognized approximately $0.1 million of debt extinguishment loss during the three months ended March 31, 2026 from this debt amendment.

During the three months ended March 31, 2026, the Company converted $0.3 million of convertible notes including $6,000 accrued interest into 1.5 million shares of common stock at a conversion price of $0.21 per share.

Convertible Notes at Fair Value

On January 26, 2026, the Company entered into aone-year convertible note (the “January Convertible Note”) with an individual investor (the “Holder”) for principal amount of$1.0 million. The January Convertible Note bears interest at 11% per annum and is convertible

into common shares at$0.25 per share at the Holder’s sole option. In addition, the Holder has the right to purchase an additionaltwo-year convertible note (the “Additional Note”) within 18 months from the issuance date of the January Convertible Note. The Additional Note shall not exceed$0.8 million and will have a conversion price at$0.50 per share.

On March 4, 2026, the Company entered into several convertible note agreements (the “March Convertible Notes”) with various commercial lenders (the “March Holders”) for an aggregate principal amount of$5 million. The March Convertible Notes bear interest at 9% per annum with a 24-month term. The March Convertible Notes are convertible into the Company’s common stock at a conversion price equal to 86% of the daily VWAP during the 10 consecutive trading days immediately after the conversion notice submission date. The amounts of such conversions are limited to 20% of the principal during any rolling 20 trading day period. The conversion restrictions will be lifted upon the Company obtaining regulatory approval of the Company’s DCVax®-L treatment for glioblastoma. In addition, the Company incurred approximately$0.5 million of issuance costs associated with the March Convertible Notes, which was recognized in interest expense on the condensed consolidated statement of operations due to the Company applying the FVO, as describe below.

The Company elected the FVO to fair value the January Convertible Note and the March Convertible Notes (collectively the “Convertible Notes at Fair Value”) on the issuance date and will subsequently remeasure at end of each reporting period. The estimated fair value of the Convertible Notes at Fair Value on the issuance date was approximate$6.7 million. The Company recognized a loss of$0.7 million upon the issuance of the Convertible Notes at Fair Value which was calculated at the difference between the principal amount and the fair value of the Convertible Notes at Fair Value.

During the three months ended March 31, 2026, the Company modified certain existing convertible notes by (i) extending the maturity dates; (ii) modifying the holder’s right to purchase additional note in the future, (iii) reducing the conversion price, and (iv) modifying the principal amount. The modifications were accounted for as a debt extinguishment as the conversion feature of the amended notes were substantially different from the original terms. As a result, the Company recognized approximately$3.3 million of debt extinguishment loss during the three months ended March 31, 2026 from these debt amendments.

During the three months ended March 31, 2026, the Company converted$3.3 million of certain convertible notes into 16 million shares of common stock at a weighted average conversion price of$0.21 per share.

For the three months ended March 31, 2026 and 2025, interest expense related to outstanding debt totaled approximately$2.2 million and$1.6 million including amortization of debt discounts totaling$0.3 million and$0.3 million, respectively.

9. Net Loss per Share Applicable to Common Stockholders

Basic loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the reporting period. Diluted loss per common share would be computed similar to basic loss per common share except that it reflects the potential dilution that could occur if dilutive securities or other obligations to issue common stock were exercised or converted into common stock. Because of the net loss from operations for each period, inclusion of such securities in the computation of loss per share would be anti-dilutive and thus they are excluded. Potentially dilutive weighted average common shares include common stock potentially issuable under the Company’s convertible notes and preferred stock, warrants and vested and unvested stock options.

The following securities were not included in the diluted net loss per share calculation because their effect was anti-dilutive as of the periods presented (in thousands):

10. Related Party Transactions

As previously reported, the Company entered into an agreement to acquire Advent on August 27, 2025, and closed on the acquisition on October 24, 2025. Prior to the acquisition, Advent was wholly owned by Toucan Holdings LLC (“Seller”). The Company’s Chairperson and Chief Executive Officer, Linda Powers, was the controlling member of the Seller. Following the acquisition, Advent is now a wholly owned subsidiary of the Company.

The consideration for the acquisition will be paid in installments overtwo years, beginning 3 months after the closing of the acquisition, with potential acceleration after regulatory approval of the Company’s DCVax®-L product. The consideration includes a combination of a cash purchase price of approximately $1.9 million (£1.4 million) and cash payment of an amount equal to the net amount of accounts payable (“Net AP”) that was due from the Company to Advent prior to the acquisition for services already performed under the existing service contracts, totaling $6.0 million, which is net of $2.3 million buyer assumed liabilities, and Excluded Amounts (relating to non-Company matters prior to the acquisition date) were retained by the Seller, totaling approximately $0.7 million (collectively, the “Purchase Consideration”). The unpaid balance will accrue interest at 7.5% annually.

During the three months ended March 31, 2026, the Company made aggregate payments of approximately $0.7 million to the Seller and accrued $0.1 million of interest expense. The unpaid balance as of March 31, 2026 was approximately $7.3 million.

11. Preferred Stock

Series C Convertible Preferred Stock

During the three months ended March 31, 2026, approximately 18,000 Series C Preferred Shares with a book value of $0.2 million were converted into 0.4 million common shares at a ratio of 1:25.

The Company determined that the Series C Shares contain contingent redemption provisions allowing redemption by the holder upon certain defined events (“deemed liquidation events”). As the event that may trigger the redemption of the Series C Shares is not solely within the Company’s control, the Series C Shares are classified as mezzanine equity (temporary equity) in the Company’s condensed consolidated balance sheets.

12. Stockholders’ Deficit

Common Stock

During the three months ended March 31, 2026, the Company received $2.9 million from the issuance of 12.4 million shares of common stock.

Stock Purchase Warrants

The following is a summary of warrant activity for the three months ended March 31, 2026 (dollars in thousands, except per share data):

Warrant Modifications

During the three months ended March 31, 2026, the Company amended certain warrants whereby the maturity dates were extended for an additional 3-6 months. The fair value of these modifications was calculated using the Black-Scholes-Merton option pricing model based on the following weighted average assumptions:

The incremental fair value attributable to the modified warrants compared to the original warrants immediately prior to the modification was calculated to be $0.3 million, which was treated as a deemed dividend and is reflected as “Deemed dividend related to warrant modifications” in the accompanying condensed consolidated statement of operations and comprehensive loss.

13. Commitments and Contingencies

Operating Lease- Lessee Arrangements

The Company has operating leases for corporate offices in the U.S. and U.K., and for manufacturing facilities in the U.K. Leases with an initial term of 12 months or less are not recorded in the balance sheet. The Company has elected the practical expedient to accountfor each separate lease component of a contract and its associated non-lease components as a single lease component, thus causing all fixed payments to be capitalized. The lease renewal options have not been included in the calculation of the lease liabilities and right-of-use (“ROU”) assets as the Company has not yet determined whether to exercise the options. Variable lease payment amounts that cannot be determined at the commencement of the lease such as increases in lease payments based on changes in index rates or usage, are not included in the ROU assets or liabilities. These are expensed as incurred and recorded as variable lease expense.

The Company’s prior office lease in the U.K. expired in July 2025. In January 2025, the Company entered into an agreement for a new office lease in the U.K. to begin in late May 2025 (the “2025 U.K. Office Lease”). An additional document, involving a reconstitution schedule, was required in order to complete the lease arrangement. However, the Company decided not to take the space and the parties did not reach agreement on the reconstitution schedule. The Company entered into a side letter with the landlord on July 30, 2025 to finalize the lease exit terms. The Company is required to pay $0.1 million each quarter for a maximum of 2.5 years. Payment will stop upon the property being leased to a new tenant. The Company recognized a contingent loss liability of $1.0 million related to the lease settlement. Upon the acquisition of Advent on October 24, 2025, an additional $0.8 million of contingent loss liability related to the 2025 U.K. Office Lease was recognized in the consolidation. The Company will recognize any remaining unpaid lease liability as a gain contingency upon the early exit of the lease liability. As of March 31, 2026, the Company had approximately $1.2 million contingent loss liability related to the 2025 U.K. Office Lease.

At March 31, 2026, the Company had operating lease liabilities of approximately $4.6 million for both the 20-year lease of the building for the manufacturing facility in Sawston, U.K., and the current office lease in the U.S. and ROU assets of approximately $4.1 million for the Sawston lease and U.S. office lease, included in the condensed consolidated balance sheet.

The following summarizes quantitative information about the Company’s operating leases (amount in thousands):

The Company recorded lease costs as a component of general and administrative expense during the three months ended March 31, 2026 and 2025, respectively.

Maturities of our operating leases, excluding short-term leases and sublease agreement, are as follows:

German Tax Matter

There has been no material update to the disclosure in our Form 10-K filed on April 15, 2026.

Other Contingent Payment Obligation

As of March 31, 2026, the Company had contingent payment obligations of $1.7 million, which are related to a gain contingency from non-dilutive funding agreements with various investors. These agreements are accounted for under ASC 470 and are recognized as contingent payment obligations on the Company’s condensed consolidated balance sheet. The Company’s payment obligations only apply when such are received by the Company.

14. Subsequent Events

The Company entered into a Commercial Loan Agreement with a commercial lender as of May 12, 2026 for funding of $7 million. There are no repayments during the first 8 months of the term – payments will start on January 11, 2027 and will be made in 14 equal monthly installments at 110% of the pro rata principal amount plus accrued interest. There isten percent original issue discount, the interest rate is 8% and the term is 22 months. This funding is designated for certain upcoming capital expenditures and certain upcoming operating expenses.