X4 Pharmaceuticals, Inc.

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On June 30, 2026, of X4 Pharmaceuticals, Inc. (the “Company”) appointed Kelly Gold as a Class II director of the Company, effective as of July 1, 2026. In connection with Ms. Gold’s appointment, the size of the Company’s board of directors (the “Board”) was increased from five to six directors. Ms. Gold has also been appointed to serve on the Audit Committee of the Board. Ms. Gold, age 49, has served as Chief Financial Officer of CAMP4 Therapeutics Corporation, a clinical-stage biopharmaceutical company (Nasdaq: CAMP), since April 2022. Ms. Gold previously served as CAMP4’s Chief Business Officer from April 2021 to March 2022, and held positions of increasing responsibility in Finance and Corporate Development at CAMP4 from 2017 to March 2021. Ms. Gold previously served as Associate Director, Strategic Corporate Finance at Biogen Inc. (Nasdaq: BIIB) from 2014 to 2017, where she provided financial leadership for the company’s late stage and marketed rare disease programs and developed long term strategic financial trajectories for the R&D organization. Ms. Gold also previously served as a Healthcare Investment Banking Associate at Deutsche Bank from 2009 to 2013, where she worked in the healthcare investment banking group. Ms. Gold earned bachelor’s degrees in Life Sciences and Mechanical Engineering from Queen’s University in Ontario and an MBA from the MIT Sloan School of Management. In connection with her appointment to the Board, Ms. Gold will be entitled to receive compensation in accordance with the Company’s non-employee director compensation policy as generally described in the Company’s Definitive Proxy Statement filed on March 20, 2026. Ms. Gold is also entering into the Company’s standard form of indemnification agreement, a form of which was previously filed as Exhibit 10.36 to Amendment No. 1 to the Company’s Registration Statement on Form S-1 filed on November 6, 2017. There are no arrangements or understandings between Ms. Gold and any other person pursuant to which she was appointed as director of the Company; there are no family relationships between Ms. Gold and any director or executive officer of the Company; and Ms. Gold is not a party to any transactions of the type that would require disclosure under Item 404(a) of Regulation S-K.

Item 7.01 Regulation FD Disclosure. A copy of the Company’s press release announcing the foregoing appointment is furnished hereto as Exhibit 99.1. The information in this Item 7.01 (including Exhibit 99.1) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended or the Exchange Act, except as expressly set forth by specific reference in such a filing.