Statement of Changes in Beneficial Ownership (4)

FORM 4

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Flynn James E	2. Issuer Name and Ticker or Trading Symbol Mirum Pharmaceuticals, Inc. [ MIRM ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    __X__ 10% Owner _____ Officer (give title below)    __X__ Other (specify below) * Possible Member of 10% Group
(Last)          (First)          (Middle) 345 PARK AVENUE SOUTH, 12TH FLOOR,	3. Date of Earliest Transaction (MM/DD/YYYY) 7/9/2021
(Street) NEW YORK, NY 10010 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	7/9/2021		S		99325	D	$15.810 (1)	0	I	Through Deerfield Special Situations Fund, L.P. (2)(3)
Common Stock								1558456	I	Through Deerfield Healthcare Innovations Fund, L.P. (2)(3)
Common Stock								1724456	I	Through Deerfield Private Design Fund IV, L.P. (2)(3)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:
(1)	The price reported in Column 4 represents a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.81 to $15.91, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(2)	This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt IV, L.P. is the general partner of Deerfield Private Design Fund IV, L.P. ("Fund IV"). Deerfield Mgmt, L.P. is the general partner of Deerfield Special Situations Fund, L.P. ("Deerfield Special Situations"). Deerfield Mgmt HIF, L.P. is the general partner of Deerfield Healthcare Innovations Fund, L.P. (collectively with Fund IV and Deerfield Special Situations, the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P., Deerfield Mgmt IV, L.P., Deerfield Mgmt HIF, L.P. and Deerfield Management Company, L.P.
(3)	In accordance with Instruction 4 (b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

Remarks: Jonathan Isler, Attorney-in-Fact: Power of Attorney, which is hereby incorporated by reference to Exhibit 24 to a Form 3 with regard to Proteon Therapeutics, Inc. filed with the Securities and Exchange Commission on August 4, 2017 by Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield Management Company, L.P., and James E. Flynn.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Flynn James E 345 PARK AVENUE SOUTH, 12TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Mgmt HIF, L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR 37TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Mgmt IV, L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) 345 PARK AVENUE SOUTH, 12TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Private Design Fund IV, L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Healthcare Innovations Fund, L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR 37TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Mgmt L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR 37TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group
Deerfield Special Situations Fund, L.P. 345 PARK AVENUE SOUTH, 12TH FLOOR 37TH FLOOR NEW YORK, NY 10010		X		* Possible Member of 10% Group

Signatures
/s/ Jonathan Isler, Attorney-in-Fact		7/13/2021
**Signature of Reporting Person		Date