MIRM

SEC source: 0001209191-22-034648 · doc4.xml · derivative · entry 1

Brege Laura · CIK 0001365619 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-034641 · doc4.xml · derivative · entry 1

Fairey William · CIK 0001727275 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,750

Underlying: Common Stock · 12,750 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-034638 · doc4.xml · derivative · entry 1

Brosgart Carol L · CIK 0001614724 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,583

Underlying: Common Stock · 15,583 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-034635 · doc4.xml · derivative · entry 1

Fischer Laurent · CIK 0001379344 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-034630 · doc4.xml · derivative · entry 1

Heron Patrick J · CIK 0001365617 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-034628 · doc4.xml · derivative · entry 1

O'Donnell Niall · CIK 0001780235 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2032-06-01

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2023 annual stockholder meeting.

SEC source: 0001209191-22-028725 · doc4.xml · nonDerivative · entry 1

Vig Pamela · CIK 0001780069 · Head of Research & Development

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 21,242

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 807 shares by the Reporting Person on May 10, 2022 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-22-028719 · doc4.xml · nonDerivative · entry 1

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 29,686

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 1,125 shares by the Reporting Person on May 10, 2022 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-22-028728 · doc4.xml · nonDerivative · entry 1

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,400

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 1,169 shares by the Reporting Person on May 10, 2022 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-22-028726 · doc4.xml · nonDerivative · entry 1

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 96,452

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 1,454 shares by the Reporting Person on May 10, 2022 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-22-028722 · doc4.xml · nonDerivative · entry 1

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 69,527

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 1,500 shares by the Reporting Person on May 10, 2022 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-22-002433 · doc4.xml · derivative · entry 3

Vig Pamela · CIK 0001780069 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 60,000

Underlying: Common Stock · 60,000 shares

Expires 2032-01-05

F2 · derivative.exercise_date: 1/4th of the shares vest one year after January 6, 2022 (the "Vesting Commencement Date") and the balance of the shares vest in a series of 36 successive equal monthly installments measured from the first anniversary of the Vesting Commencement Date.

SEC source: 0001209191-22-002433 · doc4.xml · nonDerivative · entry 1

Vig Pamela · CIK 0001780069 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 20,435

F1 · shares: Represents restricted stock unit award granted under the Issuer's 2019 Equity Incentive Plan.

SEC source: 0001209191-22-002426 · doc4.xml · derivative · entry 2

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 60,000

Underlying: Common Stock · 60,000 shares

Expires 2032-01-05

F2 · derivative.exercise_date: 1/4th of the shares vest one year after January 6, 2022 (the "Vesting Commencement Date") and the balance of the shares vest in a series of 36 successive equal monthly installments measured from the first anniversary of the Vesting Commencement Date.

SEC source: 0001209191-22-002426 · doc4.xml · nonDerivative · entry 1

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 28,561

F1 · shares: Represents restricted stock unit award granted under the Issuer's 2019 Equity Incentive Plan.

SEC source: 0001209191-22-002431 · doc4.xml · derivative · entry 2

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 60,000

Underlying: Common Stock · 60,000 shares

Expires 2032-01-05

F2 · derivative.exercise_date: 1/4th of the shares vest one year after January 6, 2022 (the "Vesting Commencement Date") and the balance of the shares vest in a series of 36 successive equal monthly installments measured from the first anniversary of the Vesting Commencement Date.

SEC source: 0001209191-22-002431 · doc4.xml · nonDerivative · entry 1

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 22,231

F1 · shares: Represents restricted stock unit award granted under the Issuer's 2019 Equity Incentive Plan.

SEC source: 0001209191-22-002429 · doc4.xml · derivative · entry 3

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 240,000

Underlying: Common Stock · 240,000 shares

Expires 2032-01-05

F2 · derivative.exercise_date: 1/4th of the shares vest one year after January 6, 2022 (the "Vesting Commencement Date") and the balance of the shares vest in a series of 36 successive equal monthly installments measured from the first anniversary of the Vesting Commencement Date.

SEC source: 0001209191-22-002429 · doc4.xml · nonDerivative · entry 1

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 68,027

F1 · shares: Represents restricted stock unit award granted under the Issuer's 2019 Equity Incentive Plan.

SEC source: 0001209191-22-002428 · doc4.xml · derivative · entry 2

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 60,000

Underlying: Common Stock · 60,000 shares

Expires 2032-01-05

F2 · derivative.exercise_date: 1/4th of the shares vest one year after January 6, 2022 (the "Vesting Commencement Date") and the balance of the shares vest in a series of 36 successive equal monthly installments measured from the first anniversary of the Vesting Commencement Date.

SEC source: 0001209191-22-002428 · doc4.xml · nonDerivative · entry 1

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 94,998

F1 · shares: Represents restricted stock unit award granted under the Issuer's 2019 Equity Incentive Plan.

SEC source: 0001209191-21-067068 · doc4.xml · nonDerivative · entry 2

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,561

F1 · kind: The Reporting Person's purchases of MIRM common stock reported herein were matchable under Section 16(b) of the Securities Exchange Act of 1934 with the Reporting Person's sale of 1,574 shares of MIRM common stock on October 1, 2021 at a price of $19.256. The transactions resulted in short-swing profits of $7,416.20 which the Reporting Person has disgorged to MIRM in accordance with Section 16(b) of the Securities Exchange Act of 1934.

SEC source: 0001209191-21-067068 · doc4.xml · nonDerivative · entry 1

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,811

F1 · kind: The Reporting Person's purchases of MIRM common stock reported herein were matchable under Section 16(b) of the Securities Exchange Act of 1934 with the Reporting Person's sale of 1,574 shares of MIRM common stock on October 1, 2021 at a price of $19.256. The transactions resulted in short-swing profits of $7,416.20 which the Reporting Person has disgorged to MIRM in accordance with Section 16(b) of the Securities Exchange Act of 1934.

SEC source: 0001209191-21-067067 · doc4.xml · nonDerivative · entry 1

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 28,027

F1 · kind: The Reporting Person's purchase of MIRM common stock reported herein was matchable under Section 16(b) of the Securities Exchange Act of 1934 with the Reporting Person's sale of 3,672 shares of MIRM common stock on October 1, 2021 at a price of $19.256. The transaction resulted in short-swing profits of $17,831.23 which the Reporting Person has disgorged to MIRM in accordance with Section 16(b) of the Securities Exchange Act of 1934.

SEC source: 0001209191-21-064455 · doc4.xml · nonDerivative · entry 1

Vig Pamela · CIK 0001780069 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 10,435

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 768 shares by the Reporting Person on November 10, 2021 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-21-064447 · doc4.xml · nonDerivative · entry 1

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,111

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 458 shares by the Reporting Person on November 10, 2021 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-21-064453 · doc4.xml · nonDerivative · entry 1

Tucker Edwin Jonathan · CIK 0001792296 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 45,838

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 70 shares by the Reporting Person on November 10, 2021 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-21-064450 · doc4.xml · nonDerivative · entry 1

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,231

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 958 shares by the Reporting Person on November 10, 2021 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-21-064449 · doc4.xml · nonDerivative · entry 1

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 84,998

F1 · kind: This Form 4 is being filed voluntarily to report the acquisition of 753 shares by the Reporting Person on November 10, 2021 pursuant to the Issuer's Employee Stock Purchase Plan.

SEC source: 0001209191-21-058609 · doc4.xml · nonDerivative · entry 2

Vig Pamela · CIK 0001780069 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,667

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058607 · doc4.xml · nonDerivative · entry 2

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 16,653

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058610 · doc4.xml · nonDerivative · entry 2

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 21,027

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058605 · doc4.xml · nonDerivative · entry 2

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,273

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058606 · doc4.xml · nonDerivative · entry 2

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 84,245

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058604 · doc4.xml · nonDerivative · entry 2

Tucker Edwin Jonathan · CIK 0001792296 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 45,768

F2 · shares: Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021.

SEC source: 0001209191-21-058609 · doc4.xml · nonDerivative · entry 1

Vig Pamela · CIK 0001780069 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,031

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 4,062 shares on September 29, 2021 and 4,063 shares on June 30, 2023.

SEC source: 0001209191-21-058607 · doc4.xml · nonDerivative · entry 1

Clements Ian · CIK 0001780080 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,227

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 4,687 shares on September 29, 2021 and 4,688 shares on June 30, 2023.

SEC source: 0001209191-21-058610 · doc4.xml · nonDerivative · entry 1

Peetz Christopher · CIK 0001614740 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 24,699

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 10,937 shares on September 29, 2021 and 10,938 shares on June 30, 2023.

SEC source: 0001209191-21-058605 · doc4.xml · nonDerivative · entry 1

Radovich Peter · CIK 0001650131 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,637

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 4,062 shares on September 29, 2021 and 4,063 shares on June 30, 2023.

SEC source: 0001209191-21-058606 · doc4.xml · nonDerivative · entry 1

Longpre Lara · CIK 0001780347 · Chief Development Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 85,206

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 4,062 shares on September 29, 2021 and 4,063 shares on June 30, 2023.

SEC source: 0001209191-21-058604 · doc4.xml · nonDerivative · entry 1

Tucker Edwin Jonathan · CIK 0001792296 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 47,132

F1 · shares: The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 4,062 shares on September 29, 2021 and 4,063 shares on June 30, 2023.

SEC source: 0001209191-21-052805 · doc4.xml · derivative · entry 1

Fairey William · CIK 0001727275 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 34,000

Underlying: Common Stock · 34,000 shares

Expires 2031-08-18

F1 · derivative.exercise_date: The shares vest in equal annual installments over a three year period such that the option is fully vested on the third anniversary of the date of grant.

SEC source: 0001193805-21-001014 · e620792_4-mirum.xml · nonDerivative · entry 1

Flynn James E · CIK 0001352546 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt HIF, L.P. · CIK 0001665736 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt IV, L.P. · CIK 0001713467 · 10% owner · * Possible Member of 10% Group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · * Possible Member of 10% Group

Deerfield Private Design Fund IV, L.P. · CIK 0001680307 · 10% owner · * Possible Member of 10% Group

Deerfield Healthcare Innovations Fund, L.P. · CIK 0001646981 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · * Possible Member of 10% Group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · * Possible Member of 10% Group

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 0

F1 · price: 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.

F2 · ownership.nature: 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.

F3 · ownership.nature: 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.

SEC source: 0001193805-21-000999 · e620783_4-mirum.xml · nonDerivative · entry 3

Flynn James E · CIK 0001352546 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt HIF, L.P. · CIK 0001665736 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt IV, L.P. · CIK 0001713467 · 10% owner · * Possible Member of 10% Group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · * Possible Member of 10% Group

Deerfield Private Design Fund IV, L.P. · CIK 0001680307 · 10% owner · * Possible Member of 10% Group

Deerfield Healthcare Innovations Fund, L.P. · CIK 0001646981 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · * Possible Member of 10% Group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · * Possible Member of 10% Group

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 99,325

F3 · price: The price reported in Column 4 represents a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.84 to $15.955, inclusive.

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0001193805-21-000999 · e620783_4-mirum.xml · nonDerivative · entry 2

Flynn James E · CIK 0001352546 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt HIF, L.P. · CIK 0001665736 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt IV, L.P. · CIK 0001713467 · 10% owner · * Possible Member of 10% Group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · * Possible Member of 10% Group

Deerfield Private Design Fund IV, L.P. · CIK 0001680307 · 10% owner · * Possible Member of 10% Group

Deerfield Healthcare Innovations Fund, L.P. · CIK 0001646981 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · * Possible Member of 10% Group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · * Possible Member of 10% Group

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 106,162

F2 · price: The price reported in Column 4 represents a weighted average price. The shares were sold in multiple transactions at prices ranging from $16.185 to $16.345, inclusive.

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0001193805-21-000999 · e620783_4-mirum.xml · nonDerivative · entry 1

Flynn James E · CIK 0001352546 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt HIF, L.P. · CIK 0001665736 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt IV, L.P. · CIK 0001713467 · 10% owner · * Possible Member of 10% Group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · * Possible Member of 10% Group

Deerfield Private Design Fund IV, L.P. · CIK 0001680307 · 10% owner · * Possible Member of 10% Group

Deerfield Healthcare Innovations Fund, L.P. · CIK 0001646981 · 10% owner · * Possible Member of 10% Group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · * Possible Member of 10% Group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · * Possible Member of 10% Group

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 155,401

F1 · price: The price reported in Column 4 represents a weighted average price. The shares were sold in multiple transactions at prices ranging from $16.85 to $17.55, 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 ranges set forth in footnotes 1 and 2 of this Form 4.

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0001209191-21-038951 · doc4.xml · derivative · entry 1

Heron Patrick J · CIK 0001365617 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2031-06-03

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2022 annual stockholder meeting.

SEC source: 0001209191-21-038921 · doc4.xml · derivative · entry 1

Fischer Laurent · CIK 0001379344 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2031-06-03

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of the Company's 2022 annual stockholder meeting.

SEC source: 0001209191-21-038933 · doc4.xml · derivative · entry 1

Mathers Edward T · CIK 0001328625 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,000

Underlying: Common Stock · 17,000 shares

Expires 2031-06-03

F1 · derivative.exercise_date: The shares vest on the first anniversary of the grant date, provided that the option will in any case be fully vested on the date of Company's 2022 annual stockholder meeting.

SEC source: 0001209191-21-038961 · doc4.xml · derivative · entry 1

Brosgart Carol L · CIK 0001614724 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 34,000

Underlying: Common Stock · 34,000 shares

Expires 2031-06-03

F1 · derivative.exercise_date: The shares vest in equal annual installments over a three year period such that the option is fully vested on the third anniversary of the date of grant.