Mirum Pharmaceuticals, Inc.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On September 8, 2026, Mirum Pharmaceuticals, Inc. (the “Company”) announced that, on September 2, 2026, the Company’s Board of Directors appointed Rob Myers, M.D., to succeed Joanne Quan, M.D., as the Company’s Chief Medical Officer, effective upon Dr. Myers’ beginning employment with the Company, which employment is expected to begin on September 21, 2026. Dr. Quan ceased to serve as the Company’s Chief Medical Officer effective September 2, 2026, and her termination of employment with the Company is expected to occur on October 19, 2026 (the actual date of Dr. Quan’s termination of employment, the “Separation Date”). In connection with Dr. Quan’s separation from the Company, the Company and Dr. Quan expect to enter into an agreement (the “Separation Agreement”), pursuant to which, in recognition of Dr. Quan’s service to the Company, the Company expects Dr. Quan to be entitled to the severance benefits set forth in the Company’s Amended and Restated Severance Benefit Plan as then in effect (the “Severance Plan”), subject to the terms and conditions set forth in the Severance Plan. In addition, on September 2, 2026, the Compensation Committee of the Company’s Board of Directors approved (i) an extension of the post-termination exercise period for all vested and outstanding stock options granted by the Company and held by Dr. Quan on the Separation Date to a period expiring 12 months after the Separation Date and (ii) payment on the Separation Date of Dr. Quan’s 2026 annual target bonus at the 100% achievement level. Receipt of the additional benefits described in the prior sentence are contingent upon Dr. Quan satisfying certain customary conditions to be set forth in the final Separation Agreement. Dr. Quan’s separation from the Company is expected to qualify as an involuntary termination under the Severance Plan. The foregoing description of the Separation Agreement is only a summary of the terms thereof, does not purport to be complete and is subject to, and qualified in its entirety by, the complete text of the final Separation Agreement, which the Company anticipates filing with its Quarterly Report on Form 10-Q for the three months ending September 30, 2026 or its Annual Report on Form 10-K for the year ending December 31, 2026, subject to the effective date of the Separation Agreement. Forward-Looking Statements This Current Report on Form 8-K contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Generally, the words “anticipate,” “approximately,” “contingent,” “expect,” “will,” and similar expressions or their negative, may, but are not necessary to, identify forward-looking statements. Such forward-looking statements include, but are not limited to, those regarding the anticipated occurrence and timing of Dr. Quan’s separation from the Company, expected entry by the Company and Dr. Quan into the Separation Agreement and the final terms thereof, the severance benefits the Company expects Dr. Quan to receive, and the anticipated occurrence and timing of Dr. Myers beginning employment with the Company and becoming the Company’s Chief Medical Officer. These forward-looking statements are based upon the Company’s current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, which include, without limitation, risks and uncertainties associated with the Company’s, Dr. Quan’s and Dr. Meyers’ future plans; and the risks and uncertainties associated with the Company’s business in general. Other factors that might cause such a difference include those discussed in the Company’s filings with the U.S. Securities and Exchange Commission, which include its Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K. All forward-looking statements made herein are based on information currently available to the Company as of the date of this Current Report on Form 8-K. The Company undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.