X4 Pharmaceuticals, Inc

1. Description of Business and Summary of Significant Accounting Policies

X4 Pharmaceuticals Inc., together with its subsidiaries (the “Company”), is a biopharmaceutical company developing and commercializing novel therapeutics for the treatment of rare hematology diseases. The Company continues to progress its global, pivotal Phase 3 clinical trial, (the “4WARD” trial) to evaluate the efficacy, safety, and tolerability of oral, once-daily mavorixafor (with or without stable doses of granulocyte colony-stimulating factor (“G-CSF”)) in people with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia (“CN”) who are experiencing recurrent and/or serious infections. The 52-week trial is a randomized, double-blind, placebo-controlled, multicenter study aiming to enroll up to 176 patients, with full enrollment expected by the end of the third quarter of 2026. The U.S. Food and Drug Administration (“FDA”) has granted Fast Track designation to mavorixafor for the treatment of CN, which is defined as periods lasting more than three months persistently or intermittently where there are abnormally low levels of neutrophils circulating in the blood, and may be idiopathic (of unknown origin), cyclic (episodes typically occurring every three weeks), or congenital (of genetic causation). CN disorders are rare blood conditions similarly characterized by increased risks of infections and cancer due to abnormally low levels of neutrophils in the body. In all cases, the CXCL12/CXCR4 pathway is the key regulator of neutrophil release from the bone marrow. The Company has one commercially approved product, XOLREMDI ® (mavorixafor), which has received accelerated approval in the United States from the FDA for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. The Company is committed to making XOLREMDI available to patients in need in the U.S. while maintaining its focus on its long-term strategy to successfully complete the 4WARD trial in patients with moderate and severe CN. The Company is headquartered in Boston, Massachusetts.

Basis of Presentation

The accompanying unaudited interim condensed consolidated financial statements as of and for the three months ended March 31, 2026 and 2025, respectively have been prepared in accordance with accounting principles generally accepted in the U.S. for interim financial information and with the instructions to the Quarterly Report on Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. In the opinion of management, all adjustments, consisting only of normal recurring adjustments as necessary, for the fair statement of the Company’s condensed financial position, condensed results of its operations and cash flows have been made. Operating results for the three months ended March 31, 2026 are not necessarily indicative of the results that may be expected for the entire year or for any other subsequent interim period.

These unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2025 included in its Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 17, 2026. The condensed consolidated balance sheet at December 31, 2025 that is presented in these interim condensed consolidated financial statements was derived from audited financial statements but does not include all disclosures required by GAAP.

Principles of Consolidation

The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, including X4 Pharmaceuticals (Austria) GmbH, which is incorporated in Vienna, Austria, and X4 Therapeutics, Inc. All intercompany accounts and transactions have been eliminated.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the accrual of operational and financial license milestones, the accrual of reserves for variable consideration related to product revenue, and the impairment or lack of impairment of long-lived assets including operating lease right-of-use assets and goodwill. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. As of the date of issuance of these condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s condensed consolidated financial statements.

Liquidity

The Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. Although the Company has an approved drug product, licensing and sales of the Company’s drug product over the next 12 months will not be sufficient to fund the Company’s operating expenses. Since inception, the Company has incurred significant operating losses and negative cash flows from operations, and the Company expects to continue to generate operating losses and negative cash flows from operations for the foreseeable future. For the three months ended March 31, 2026, the Company’s net loss was $20.2 million and net cash used in operating activities was $19.6 million. As of March 31, 2026, the Company had $233.7 million of cash, cash equivalents and short-term marketable securities, and an accumulated deficit of $614.8 million.

Based on its current operating plan, the Company believes (a) that its current cash, cash equivalents and short-term marketable securities will be sufficient to fund its operations for at least the next 12 months and (b) it will continue to comply with all covenants under the Hercules Loan Agreement, as defined and further described in Note 8, through at least the 12-month period from the issuance date of these condensed consolidated financial statements.

The Company is subject to risks common to companies in the biopharmaceutical industry including, but not limited to, uncertainties relating to conducting preclinical and clinical research and development, the manufacture and supply of products and product candidates for clinical and commercial use, obtaining and maintaining regulatory approvals and pricing and reimbursement for its products and product candidates, market acceptance, managing global growth and operating expenses, availability of additional capital, competition, obtaining and enforcing patents, stock price volatility, dependence on collaborative relationships and third-party service providers, dependence on key personnel, and from time to time government investigations, litigation, and potential product liability claims.

Significant Accounting Policies

The Company’s significant accounting policies are disclosed in the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 filed with the SEC on March 17, 2026. Since the date of those consolidated financial statements, there have been no material changes to the Company’s significant accounting policies.

Restricted Cash

In connection with the Company’s lease agreements for its facilities in Boston, Massachusetts, the Company maintains a letter of credit, which is secured by restricted cash, for the benefit of the respective landlord. As of December 31, 2025, restricted cash related to the Company’s former Vienna, Austria lease, which the Company terminated effective November 30, 2025, is included in other current assets and was subsequently converted to unrestricted cash during the three months ended March 31, 2026. Restricted cash related to the Boston lease is also included in other current assets.

In accordance with the Company’s Hercules Loan Agreement, the Company at all times must maintain a minimum level of cash of $15.0 million in an account or accounts in which Hercules has a first priority security interest.

Cash, Cash Equivalents, Restricted Cash and Marketable Securities

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated balance sheets to the total of amounts shown in the Company’s condensed consolidated statements of cash flows as of March 31, 2026 and December 31, 2025:

The Company’s cash equivalents consisted of money market funds invested in U.S. Treasury securities. The money market funds were valued based on quoted prices in active markets for identical assets, which represents a Level 1 measurement. All marketable securities are classified as short-term investments as all are due within one year and include investments in U.S. Treasury notes, U.S. Treasury bills and federal government agency notes. The amortized cost of each investment, individually and in aggregate, approximated fair value. The Company has evaluated each marketable security for impairment that is other-than-temporary and concluded that no marketable security was impaired as of March 31, 2026 and December 31, 2025.

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of March 31, 2026:

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of December 31, 2025:

Liabilities Measured at Fair Value

The following tables present information about the Company’s financial liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values:

The following table provides a roll-forward for the three months ended March 31, 2026 of the aggregate fair values of financial instruments for which fair values are determined using Level 3 inputs:

Valuation of Embedded Derivative Liability— The fair value of the embedded derivative liability recognized in connection with the Company’s Hercules Loan Agreement, which is associated with additional fees due to Hercules upon non-credit related events of default, was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of this embedded derivative liability, which is reported within other non-current liabilities on the condensed consolidated balance sheets, is estimated by the Company at each reporting date based, in part, on the results of third-party valuations, which were prepared based on a discounted cash flow model that considered the timing and probability of occurrence of a redemption upon an event of default, the potential amount of prepayment fees or contingent interest upon an event of default and the Company’s risk-adjusted discount rate of 17%. As of March 31, 2026 and December 31, 2025, the fair value of this derivative liability was $10 thousand.

Class C Warrant Liability—In December 2022, the Company issued Class C Warrants for the purchase of shares of its common stock in a public offering. The Class C Warrants are accounted for as a liability on the condensed consolidated balance sheet and are adjusted to fair value at period end through “change in fair value of warrant liability” on the condensed consolidated statements of operations and comprehensive (loss) income.

The Company calculated the fair value of the Class C Warrants using the Black-Scholes option pricing model, with the following inputs:

Net (Loss) Income Per Share

Basic net (loss) income per common share is calculated based on net (loss) income divided by the weighted average number of shares outstanding for the period. The calculation of diluted loss per common share excludes the impact of potential common stock as their inclusion would be to reduce net loss per common share and are thus antidilutive. The calculation of diluted income per share includes the impact of dilutive securities as described below.

Basic and diluted net (loss) income per share was calculated as follows:

Basic and diluted weighted average shares of common stock outstanding for the three months ended March 31, 2026 and 2025 includes the weighted average effect of pre-funded warrants for the purchase of shares of common stock, for which the remaining unfunded exercise price is less than or equal to $0.03 per share.

For the three months ended March 31, 2026, during which the Company recorded net loss, the Company’s potentially dilutive securities included outstanding stock options, unvested restricted stock units and warrants to purchase shares of common stock. These potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share, and thus they are considered “anti-dilutive.” Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same for this period.

For the three month period ended March 31, 2025, during which the Company recorded net income, the dilutive effect of outstanding stock options, restricted stock units, employee stock purchase plan shares and warrants were calculated using the treasury stock method, whereby all such awards were assumed to be exercised at the beginning of the period. The hypothetical proceeds from such exercises, including the average unrecognized stock compensation expense for outstanding stock options and restricted stock units, were assumed to be used to purchase outstanding common stock at the average price during the period. The net share impact of dilutive securities was added to the weighted average basic common shares outstanding to calculate weighted average diluted shares outstanding.

The Company excluded the following potential shares of common stock from the computation of diluted net (loss) income per share for the periods indicated because including them would have had an anti-dilutive effect:

Recently Issued Accounting Standards Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Disaggregation of Income Statement Expenses (Topic 220) (“ASU 2024-03”) requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The amendments in ASU 2024-03 are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The requirements in ASU 2024-03 may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company continues to evaluate the impact of the future adoption of ASU 2024-03 to its consolidated financial statements.

2. Strategic Restructuring Liability

In 2025, the Company implementedtwo strategic restructuring actions designed to sharpen operational focus and align resources with the Company’s long‑term strategy to successfully complete the 4WARD trial in patients with moderate and severe CN. These strategic restructuring actions resulted in an approximately 65% reduction in employee headcount.

The following table summarizes the Company’s liability recognized in connection with severance benefits incurred under strategic restructuring initiatives:

3. Revenue

Product Revenue, Net

During the three months ended March 31, 2026, the Company recorded net revenue $2.5 million for the sale of the Company’s drug product in the U.S. Net product revenue was $0.9 million for the three months ended March 31, 2025.

The following table summarizes the balances and activity in each of the product reserve accounts for the three months ended March 31, 2026.

The provision for contractual discounts provided to the Company’s customer is recorded as a reduction of accounts receivable. The provisions for co-pay assistance payments, contractual rebates and product returns are classified within accrued expenses.

The following table provides a rollforward of accounts receivable for the three months ended March 31, 2026.

License and Other

During the first quarter of 2025, the Company entered into a license and supply agreement (the “Norgine Agreement”) with Norgine Pharma UK Ltd. (“Norgine”). The Company analyzed the activities required under the Norgine Agreement and concluded that the arrangement was indicative of a vendor-customer relationship and would be accounted for under ASC 606. To date, the Company has received a one-time, non-refundable, up-front payment of €28.5 million and a regulatory milestone payment of€0.5 million, which are included the transaction price. All other future regulatory-based milestone payments, which represent variable consideration, have been fully constrained as these are not yet considered probable. The Company has also excluded from the transaction price future royalty payments that are based on units sold by Norgine and future cumulative revenue-based milestone payments under the applicable practical expedient.

Under the Norgine Agreement, the Company’s promises include a) the delivery of a license, b) research and development services for certain components of WHIM clinical studies, c) research and development services for the global Phase 3 trial of XOLREMDI for CN, and d) the option for delivery of commercial drug supply.

The following table summarizes the allocation of transaction price to the performance obligations under the Norgine Agreement based on the weighting of estimated stand-alone selling price for these performance obligations at the inception of the agreement.

The following table provides a rollforward of deferred revenue three months ended March 31, 2026.

As of March 31, 2026, deferred revenue related to the Norgine Agreement was $1.0 million, of which $0.9 million was current.

4. Inventory

Inventory consists of the following:

5. Property and Equipment

Property and equipment, net consisted of the following:

Depreciation expense related to property and equipment was approximately $36 thousand and $289 thousand for the three months ended March 31, 2026 and 2025, respectively.

6. Intangible Assets, Net

As of March 31, 2026, the Company’s net definite-lived intangible assets, which is comprised of the capitalization of certain milestone payments made or accrued related to its license agreement for the intellectual property contained in its drug product, included a gross intangible asset of$10.5 million, less accumulated amortization of $1.4 million for a net intangible asset of $9.1 million. The Company amortizes the intangible asset to cost of revenue over the remaining life of the underlying patent protecting the intellectual property through 2038.

As of March 31, 2026, amortization expense for the next five years and beyond is summarized as follows (in thousands):

The Company began amortizing its finite-lived intangible assets in April 2024 over a 14-year period based on the expected patent exclusivity period for XOLREMDI. Amortization expense totaled $0.2 million for the three months ended March 31, 2026 and $0.2 million for the comparable prior year period. Amortization expense is recorded as a component of cost of revenue on the condensed consolidated statements of operations and comprehensive (loss) income.

7. Accrued Expenses

Accrued expenses consisted of the following:

8. Long-Term Debt

Long-term debt consisted of the following:

Hercules Loan Agreement

The Company is party to the Second Amended and Restated Loan and Security Agreement, as amended, (the “Hercules Loan Agreement”) with Hercules Capital Inc., which provides for an aggregate term loan facility of up to $107.5 million, under which the Company has borrowed an aggregate of $75.0 million of term loans, representing the maximum borrowings allowable as of March 31, 2026. The Hercules Loan Agreement is described in Note 11 to the consolidated financial statements contained in the Company’s Annual Report on Form 10-K filed with the SEC on March 17, 2026.

The Company recognized interest expense under the Hercules Loan Agreement as follows:

The annual effective interest rate on the Hercules Loan Agreement as of March 31, 2026 was 11.2%. There wereno principal payments due or paid under the Hercules Loan Agreement during the three months ended March 31, 2026 and 2025. As of

March 31, 2026, future principal and accrued end-of-term payments of $76.9 million under the Hercules Loan Agreement are due on July 1, 2027.

9. Leases

The Company has a lease agreement for its facility in Boston, Massachusetts, which is the Company’s principal executive office. There are no restrictions or financial covenants associated with this lease agreement. The Company had an operating lease for approximately 1,200 square meters of laboratory and office space in Vienna, Austria that commenced in February 2021 for a term ofseven years. Effective November 30, 2025, the Company terminated the lease in accordance with a lease amendment entered into with the landlord. Accordingly, the Company accelerated the amortization of the right-of-use asset tozero and adjusted the remaining lease obligation tozero as of December 31, 2025.

The components of lease expense for the three months ended March 31, 2026 and 2025 were as follows:

Maturities of lease liabilities due under lease agreements that have commenced as of March 31, 2026 are as follows (in thousands):

10. Commitments and Contingencies

The Company has agreements with contract research organizations (“CROs”) pursuant to which the Company and the CROs are conducting clinical trials. The Company may terminate these agreements by providing notice pursuant to the contractual provisions of such agreements and would incur early termination fees. The Company has agreements with contract manufacturing organizations (“CMOs”) for the production of mavorixafor for use in clinical trials and for the commercial supply of XOLREMDI. The Company’s agreement with the CMO who produces batches of drug substance for use in the Company’s clinical and commercial drug supply contains cancellation provisions that would require the Company to pay up to the full contract value upon cancellation. As of March 31, 2026, the Company has approximately $2.1 millionof such commitments in place subject to cancellation provisions.

License Agreements

See Note 5 to the Company’s Annual Report on Form 10-K filed with the SEC on March 17, 2026 for a description of licensing agreements, which commit the Company to contingent milestone and royalty fees based on future operational events.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company to, among other things, indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnification obligations. The Company is not currently aware of any indemnification claims and hasnot accrued any liabilities related to such obligations in its condensed consolidated financial statements as of March 31, 2026 or December 31, 2025.

Legal Proceedings

The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to any legal proceedings.

11. Equity Transactions

ATM Sales Agreement

The Company was a party to a Controlled Equity Offering SMSales Agreement (“ATM”), dated as of August 7, 2020, pursuant to which the Company offered and sold shares of its common stock through one or more investment banks. The Company sold $24.2 million of its common stock, net of offering costs, under the ATM. The Company terminated the ATM on March 30, 2026.

12. Stock-Based Compensation

As of March 31, 2026, there is an aggregate of approximately 1.4 million shares of common stock available for issuance under the Company’s equity incentive plans, including 0.1 million shares of common stock remain available for issuance under the Amended and Restated 2017 Employee Stock Purchase Plan.

Stock Option Valuation

The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted:

As of March 31, 2026, total unrecognized compensation expense related to unvested stock options and restricted stock units was $19.8 million, which is expected to be recognized over a weighted average period of 2.9 years.

Stock Options

The following table summarizes the Company’s stock option activity for the three months ended March 31, 2026:

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock to the extent the stock option had a lower exercise price. There were no options exercised in 2025 and 2024. The weighted average grant-date fair value per share of stock options granted during the three months ended March 31, 2026 and 2025 was $3.36 and $14.10, respectively.

Restricted Stock Units

The following table summarizes the Company’s restricted stock unit activity for the three months ended March 31, 2026:

Outstanding restricted stock units include performance-based restricted stock units (“PRSUs”), which will vest based on the achievement of an operational milestone. The Company considers the achievement of the remaining operational milestone related to outstanding PRSUs to be probable. Stock-based compensation expense has been recognized for these awards using the accelerated attribution model based on the fair value of the awards as of the date of grant and management’s best estimate of the date the probable operational milestone will be achieved. The Company updates its estimates related to the probability and timing of achievement of the operational milestones each period until the award either vests or is forfeited.

Stock-Based Compensation

Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive (loss) income as follows:

13. Income Taxes

The Company did not record a material U.S. federal, state or international provision or benefit for income taxes in its condensed consolidated statement of operations and comprehensive (loss) income for the three months ended March 31, 2026 and 2025. The Company continues to maintain a valuation allowance against all remaining net deferred tax assets. The Company believes that it is more likely than not that it will not realize a future tax benefit of these attributes as the Company expects to continue to generate operating losses. Ultimate realization of any deferred tax asset is dependent on the Company’s ability to generate sufficient future taxable income in the appropriate tax jurisdiction before the expiration of carryforward periods, if any. The Company will continue to monitor the valuation allowance assessment throughout the year.

14. Segment Information

The Company has defined its Chief Operating Decision Maker (“CODM”) as the Executive Chairman. The CODM manages the Company’s operations as a single operating segment, which comprises its single reportable segment, for the purposes of assessing performance and making operating decisions. The Company’s focus is on the research, development and commercialization of novel therapeutics for the treatment of rare diseases. The Company’s research, development and commercialization efforts are focused on its lead molecule, mavorixafor, which is being marketed in the U.S. under the trade name XOLREMDI. The CODM uses the Company’s condensed consolidated net (loss) income to monitor actual results as compared to forecast in assessing segment performance and allocation of resources.

The Company derives its revenue from the sale of XOLREMDI in the U.S. and from licensed rights and product sales of mavorixafor for other non-U.S. territories. The Company recognized $2.5 million and $0.9 million of revenue from its U.S. customer and $0.2 million and $27.9 million of revenue from a customer in the United Kingdom for the three months ended March 31, 2026 and 2025, respectively.

The measure of profit for the segment is net (loss) income and consisted of the following for the three months ended March 31, 2026, and 2025:

(a) Other segment items primarily include cost of revenue, non-compensation departmental costs within sales, general and administrative departments, certain unallocated external costs within research and development, stock-based compensation expense, stock appreciation rights compensation expense, severance expense, other income (expense), and provision for income taxes.

The CODM only receives and reviews information regarding segment assets at the consolidated level. Certain other entity-wide disclosures are included elsewhere in these condensed consolidated financials statements. As of March 31, 2026, the Company’s single operating segment had long-lived assets, including property and equipment and right-of-use assets, of $1.2 million, which were located in the U.S. As of December 31, 2025, the operating segment’s long-lived assets were $1.6 million, all of which were located in the U.S.

15. Subsequent Events

MAA Approval

In January 2025, the European Medicines Agency (“EMA”) validated the Company’s Marketing Authorisation Application (“MAA”) for processing. On April 29, 2026, the European Commission granted marketing authorization for XOLREMDI® (mavorixafor) capsules for the treatment of patients with WHIM syndrome in the European Union.