Nature of the Business and Basis of Presentation

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Nature of the Business and Basis of Presentation

NATURE OF THE BUSINESS AND BASIS OF PRESENTATION

X4 Pharmaceuticals, Inc. (together with its subsidiaries, the “Company”) is a biopharmaceutical company discovering, developing and commercializing novel therapeutics for the treatment of rare diseases and those with limited treatment options, with a focus on conditions resulting from dysfunction of the immune system. On April 29, 2024, the Company announced that the FDA approved the Company’s New Drug Application (“NDA”) for mavorixafor, which is being marketed in the U.S. under the trade name XOLREMDI®, for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM syndrome (warts, hypogammaglobulinemia, infections, and myelokathexis), to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. The Company has launched XOLREMDI in WHIM syndrome in the U.S. and has filed for regulatory approvals to commercialize mavorixafor outside of the U.S. The U.S. approval of XOLREMDI in the WHIM syndrome indication is the first for mavorixafor, which is an orally bioavailable selective antagonist of chemokine receptor CXCR4, a key regulator of the movement of immune cells throughout the body. Due to its ability to increase the mobilization of white blood cells from the bone marrow into the bloodstream, the Company believes that mavorixafor has the potential to provide therapeutic benefit across a variety of immune system disorders in addition to WHIM syndrome. The Company has completed a Phase 2 study evaluating the safety and efficacy of mavorixafor as a monotherapy and in combination with human G-CSF in people with certain chronic neutropenic disorders. Results from this six-month Phase 2 study showed mavorixafor was generally well tolerated and able to durably increase study participants’ mean absolute neutrophil count (“ANC”) both as a monotherapy and in combination with G-CSF. The Company is actively enrolling participants in a global, pivotal Phase 3 clinical trial of mavorixafor (the 4WARD study) that aims to evaluate the efficacy, safety, and tolerability of oral once-daily mavorixafor with or without G-CSF in people with congenital or acquired primary autoimmune and idiopathic chronic neutropenia who are experiencing recurrent and/or serious infections. The Company is headquartered in Boston, Massachusetts and previously had a research facility in Vienna, Austria.

Going Concern Assessment—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 consolidated financial statements are issued. Although the Company has an approved drug product, 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. As of December 31, 2024, the Company had $102.1 million of cash, cash equivalents and short-term marketable securities and an accumulated deficit of $515.4 million. For the year ended December 31, 2024, the Company’s net losses were $37.5 million and net cash used in operating activities of $130.9 million.

The Company has a covenant (the “Minimum Cash Covenant”) under its Second Amended and Restated Loan and Security Agreement, as amended, (the “Hercules Loan Agreement”) with Hercules Capital Inc. (“Hercules”), that requires that the Company maintain a minimum level of cash of $15 million, which represents 20% of outstanding borrowings under the Hercules Loan Agreement. Based on its current operating plan, which includes estimates of anticipated cash inflows from product sales and cash outflows from operating expenses, the Company believes there is a risk that it will not meet the conditions of the Minimum Cash Covenant within the 12-month period from the issuance date of these consolidated financial statements. In such case, Hercules could accelerate the principal payments on the Company’s outstanding loans and the Company potentially would not have sufficient cash, cash equivalents and short-term marketable securities to settle such obligations. Accordingly, management has concluded that this condition meets the standard for raising substantial doubt about the Company’s ability to continue as a going concern. The Company does not have adequate financial resources to fund its forecasted operating costs for at least one year after the date that these consolidated financial statements are issued. The accompanying consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty. Accordingly, the consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and which contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

To alleviate the risk that the Company violates the Minimum Cash Covenant and to finance its future operations, the Company will need to raise additional capital, which cannot be assured, and/or modify such Minimum Cash Covenant. Unless and until the Company reaches profitability in the future, it will require additional capital to fund its operations, which could be raised through a combination of equity offerings, debt financings, other third-party funding, marketing and distribution arrangements, or other collaborations and strategic alliances. If the Company is unable to obtain funding, it could be forced to delay, reduce, or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which would adversely affect its business prospects, or it may be unable to continue operations.

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 the Company’s 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.

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