Certain information in this document identified by brackets has been omitted because it is both not material and would be competitively harmful if publicly disclosed. Execution Version REVENUE INTEREST PURCHASE AGREEMENT

Certain information in this document identified by brackets has been omitted because it is both not material and would be competitively harmful if publicly disclosed.

REVENUE INTEREST PURCHASE AGREEMENT

dated as of December 8, 2020

MIRUM PHARMACEUTICALS, INC.,

the Purchasers from time to time party hereto

MULHOLLAND SA LLC, as Purchaser Agent

ARTICLE I DEFINITIONS1

ARTICLE II PURCHASE OF REVENUE INTERESTS; PAYMENTS22

ARTICLE III REPRESENTATIONS AND WARRANTIES OF THE COMPANY27

ARTICLE IV REPRESENTATIONS AND WARRANTIES OF THE PURCHASERS37

ARTICLE V COVENANTS38

ARTICLE VI TERMINATION50

ARTICLE VII PURCHASER AGENT51

ARTICLE VIII MISCELLANEOUS55

SCHEDULES TO DISCLOSURE LETTER

EXHIBITS TO DISCLOSURE LETTER

REVENUE INTEREST PURCHASE AGREEMENT

This REVENUE INTEREST PURCHASE AGREEMENT (as amended, supplemented or otherwise modified from time to time, this "Agreement") is made and entered into as of December 8, 2020, by and among Mirum Pharmaceuticals, Inc., a Delaware corporation (the "Company"), the Purchasers from time to time party hereto (each, a "Purchaser" and collectively, the "Purchasers") and Mulholland SA LLC, as collateral agent and administrative agent for the Purchasers (the "Purchaser Agent").

WHEREAS, the Company wishes to obtain financing to support the further development and commercialization of the Included Products (as hereinafter defined) and other general corporate purposes; and

WHEREAS, the Purchasers wish to purchase the Revenue Interests (as hereinafter defined) from the Company, and the Company wishes to sell, assign and transfer the Revenue Interests to the Purchasers in consideration for its payment of the Purchaser Payments (as hereinafter defined) all upon and subject to the terms and conditions hereinafter set forth.

NOW, THEREFORE, in consideration of the mutual covenants, agreements, representations and warranties set forth herein, the parties hereto agree as follows:

Section 1.01Definitions.

The following terms that are defined in the UCC (as hereinafter defined) are used in this Agreement as so defined (and, in the event any such term is defined differently for purposes of Article 9 of the UCC than for any other purpose or purposes of the UCC, the Article 9 definition shall govern): Account, Chattel Paper, Commercial Tort Claim, Commodity Account, Commodity Intermediary, Deposit Accounts, Documents, Electronic Chattel Paper, Equipment, General Intangibles, Goods, Instruments, Inventory, Investment Property, Letter of Credit Rights, Proceeds, Securities Account, Securities Intermediary and Tangible Chattel Paper. In addition, the following, as used herein, shall have the following meanings:

"Acquisition" means (a) any transaction, or any series of related transactions, by which any Person directly or indirectly, by means of a take-over bid, tender offer, amalgamation, merger, purchase of assets or similar transaction having the same effect as any of the foregoing, (i) acquires any business or product or all or substantially all of the assets of any Person engaged in any business or any business, product, business line or product line, division or other unit operation of any Person, (ii) acquires control of securities of a Person engaged in a business representing more than 50% of the ordinary voting power for the election of directors or other governing body if the business affairs of such Person are managed by a board of directors or other governing body or (iii) acquires control of more than 50% of the ownership interest in any Person engaged in any business that is not managed by a board of directors or other governing body and (b) any Product In-License.

"Acquisition Cost" means consideration paid or payable for an Acquisition (including all milestone, maintenance and/or similar payments, research and development spend, earnouts (whether earned or contingent), deferred purchase price and any other contractual commitment, whether fixed or contingent), excluding (i) royalties on sales calculated on an arm's-length basis and (ii) future milestones that would not be due and payable if the Company or its Subsidiary exercised a right of contractual termination without

penalty at the sole option of the Company or its Subsidiary (for the avoidance of doubt, all milestone, maintenance and/or similar payments actually made will constitute Acquisition Cost).

"Additional Payment Date" means the date (i) specified in the applicable notice sent to the Purchaser Agent pursuant to Section 2.03(b)(iv)(A) with regards to an Additional Payment and (ii) agreed to by the Required Purchasers in their sole discretion.

"Additional Payments" mean one or more payments of up to $50,000,000 in the aggregate with all other Additional Payments, which shall be paid by the Purchasers on an Additional Payment Date in accordance with Section 2.03(a)(iv).

"Affiliate" means any Person that Controls, is Controlled by, or is under common Control with another Person.

"Agreement" has the meaning set forth in the first paragraph hereof.

"Alagille Syndrome" means a rare genetic disorder that results from a mutation in one copy of the JAG1 gene or the NOTCH2 gene and affects the liver by preventing the drainage of bile.

"Annual Net Sales" means, as of any date of determination, the amount of world-wide Net Sales of all Included Products for the applicable calendar year.

"Applicable Law" means, with respect to any Person, all laws, rules, regulations and orders of Governmental Authorities applicable to such Person or any of its properties or assets.

"Applicable Percentage" means the percentage based on the applicable portion of Annual Net Sales for any calendar year as set forth in the chart below:

provided that (i) if the Purchasers have received Revenue Interest Payments (excluding, for avoidance of doubt, any payment of interest made in accordance with Section 2.02(e)) under this Agreement in an amount equal to or greater than 110.0% of the Cumulative Purchaser Payments on or prior to December 31, 2026, the Applicable Percentage for Tier 1 shall decrease to 2.00% and the Applicable Percentage for Tier 3 shall decrease to 0.00% for all subsequent calendar years beginning on January 1, 2027 and (ii) if the Purchasers have not received Revenue Interest Payments (excluding, for avoidance of doubt, any payment of interest made in accordance with Section 2.02(e)) under this Agreement in an amount equal to or greater than 110.0% of the Cumulative Purchaser Payments on or prior to December 31, 2026, the Applicable Percentages for Tier 1, Tier 2 and Tier 3 shall be increased for all subsequent calendar years

beginning on January 1, 2027 to a single defined rate (with no separate Tiers) that would have provided the Purchasers with an amount equal to 110.0% of the Cumulative Purchaser Payments on or prior to December 31, 2026 had such rate applied to Tier 1 from and after the Effective Date. Solely as used in this definition of "Applicable Percentage" and notwithstanding anything to the contrary elsewhere in this Agreement, the amount of Revenue Interest Payments shall be calculated without giving effect to payments made in accordance with Section 2.02(d).

"Audit Costs" means, with respect to any audit of the books and records of the Company and its Affiliates and Licensees with respect to amounts payable or paid under this Agreement, the reasonable and documented out-of-pocket cost of such audit, including all reasonable and documented fees, costs and expenses incurred in connection therewith.

"Audited Financial Statements" has the meaning set forth in the definition of "Financial Statements".

"Bankruptcy Event" means the occurrence of any of the following:

(a)the Company or any Subsidiary shall commence any case, proceeding or other action (i) under any existing or future law of any jurisdiction, domestic or foreign, relating to bankruptcy, insolvency, reorganization, relief of debtors or the like, seeking to have an order for relief entered with respect to it, or seeking to adjudicate it bankrupt or insolvent, or seeking reorganization, arrangement, adjustment, winding-up, administration, protection, liquidation or dissolution (other than a solvent winding-up, dissolution or liquidation of a Subsidiary into the Company or a Subsidiary Guarantor), composition or other relief with respect to it or its debts, or (ii) seeking appointment of a receiver, interim receiver, receiver and manager, trustee, administrator, administrative receiver, custodian or other similar official for it or for all or any portion of its assets, or the Company or any Subsidiary shall make a general assignment for the benefit of its creditors or enter into a composition, compromise, assignment or arrangement with any of its creditors (whether by way of a voluntary arrangement, scheme of arrangement, deed of compromise or otherwise);

(b)there shall be commenced against the Company or any Subsidiary any case, proceeding or other action seeking to adjudicate it bankrupt or insolvent, or seeking dissolution, liquidation, administration, winding up, reorganization, arrangement, adjustment, protection, relief of debtors, or seeking the entry of an order for relief or the appointment of a receiver, interim receiver, receiver and manager, trustee, administrator, administrative receiver, custodian or other similar official for any such Person or for any substantial part of its property, and either such proceeding shall remain undismissed or unstayed for a period of forty-five (45) days or any of the actions sought in such proceeding (including, without limitation, the entry of an order for relief against any such Person or the appointment of a receiver, interim receiver, receiver and manager, trustee, administrator, administrative receiver, custodian or other similar official for it or for any substantial part of its property) shall occur;

(c)the Company or any Subsidiary shall be generally not paying its debts as such debts become due or shall admit in writing its inability to pay its debts generally;

(d)a receiver, interim receiver, receiver and manager, trustee, administrator, administrative receiver, custodian or other similar official is appointed, either voluntarily or involuntarily, to or in respect of the Company or any Subsidiary or the whole or any part of the property, assets or undertaking of the Company or any Subsidiary;

(e)there shall be commenced against the Company or any Subsidiary any case, proceeding or other action seeking issuance of a warrant of attachment, execution, distraint or similar process against (i) all or a substantial portion of its assets and/or (ii) any Included Product or any Collateral, which results in

the entry of an order for any such relief which shall not have been vacated, discharged, stayed, satisfied or bonded pending appeal within forty-five (45) days from the entry thereof;

(f)the Company or any Subsidiary shall be insolvent as defined in any statute of the United States Bankruptcy Code or in the fraudulent conveyance or fraudulent transfer statutes of the State of Delaware or other applicable jurisdiction of organization; or

(g)an affirmative vote by the applicable Board to commence any case, proceeding or other action described in clause (a) above or any other action by the Company or any Subsidiary to otherwise cause, consent to, approve or acquiesce in any of the acts described in clauses (a) through (f) inclusive above.

"Board" means the Board of Directors of the Company or board of directors or similar governing body of any Subsidiary, as applicable.

"Business Day" means any day other than a Saturday, a Sunday, any day which is a legal holiday under the laws of the State of New York, or any day on which banking institutions located in the State of New York are required by law or other governmental action to close.

"Call Closing Date" has the meaning set forth in Section 5.07(b).

"Call Option" has the meaning set forth in Section 5.07(b).

"Change in Law" means the occurrence, after the Effective Date (or, with respect to any successors or assigns of any Purchaser, after the date such Person acquires its interest hereunder, except that, to the extent that the predecessor or assignor of such Person was entitled to additional amounts in accordance with Section 5.12(d)(ii) immediately before such Person acquires its interest hereunder, and payments to such Person (or by such Person to its Tax Affiliate) are subject to withholding on the date such Person acquires its interest hereunder, such Person shall be entitled to additional amounts in accordance with Section 5.12(d)(ii) to the same extent as its predecessor or assignor), of any of the following: (a) the adoption or taking effect of any law, rule, regulation or treaty, (b) any change in any law, rule, regulation or treaty or in the administration, interpretation, implementation or application thereof by any Governmental Authority or (c) the making or issuance of any request, rule, guideline or directive (whether or not having the force of law) by any Governmental Authority; provided that notwithstanding anything herein to the contrary, (x) the Dodd-Frank Wall Street Reform and Consumer Protection Act and all requests, rules, guidelines or directives thereunder or issued in connection therewith and (y) all requests, rules, guidelines or directives promulgated by the Bank for International Settlements, the Basel Committee on Banking Supervision (or any successor or similar authority) or the United States or foreign regulatory authorities, in each case pursuant to Basel III, shall in each case be deemed to be a "Change in Law", regardless of the date enacted, adopted or issued.

"Change of Control" means, at any time, the occurrence of any of the following events or circumstances:

(a)the acquisition by any "person" or "group" (within the meaning of Sections 13(d)(3) or 14(d)(2) of the Securities Exchange Act of 1934, as amended) of beneficial ownership of any Equity Interests of the Company, if after such acquisition, such "person" or "group" would be the "beneficial owner" (as defined in Rule 13d-3 under the Securities Exchange Act of 1934, as amended), directly or indirectly, of securities of the Company representing more than fifty percent (50%) of the combined voting power of the Company's then outstanding securities entitled to vote generally in the election of directors;

(b)a merger or consolidation of the Company with any other Person, other than a merger or consolidation of the Company in which the Company is the surviving Person and in which the persons holding more than fifty percent (50%) of the combined voting power of the Company's voting securities outstanding immediately prior to such merger or consolidation, continue to hold at least fifty percent (50%) of the combined voting power of the Company's voting securities outstanding immediately after such merger or consolidation;

(c)any Transfer by any Obligor to another Person (other than a Transfer permitted pursuant to Section 5.10(a)(x)) of any Collateral;

(d)any Transfer of all or substantially all of the assets of the Company and its Subsidiaries on a consolidated basis to a Third Party; or

(e)a "Change of Control" (or any comparable term or provision) or "Fundamental Change" (or any comparable term or provision) under or with respect to any of the Equity Interests or Material Indebtedness of the Company or any Subsidiary.

"Clinical Trial" means any human clinical trial of the Included Products conducted by or on behalf of the Company or any Subsidiary.

"Clinical Updates" means material information and developments with respect to each Clinical Trial.

"CMC Contract" means any Contract involving the chemistry, manufacturing or control (CMC) of any Included Product.

"Code" means the Internal Revenue Code of 1986, as amended.

"Collateral" means (i) all Product Assets, (ii) all Accounts, Contracts, Commercial Tort Claims, Documents, General Intangibles (including all Intellectual Property), Equipment, Goods, Instruments, Inventory, Investment Property, Payment Intangibles, Letter of Credit Rights and Supporting Obligations constituting Product Assets, (iii) all Pledged Equity and Pledged Investment Property, Deposit Accounts, Securities Accounts, cash or cash equivalents, wherever located and (iv) any and all Proceeds, products, rents, royalties and profits of or from any and all of the foregoing; provided that Collateral shall not include the Excluded Property (as defined in the Security Agreement).

"Combination Product" means either: (a) any Included Product that contains or comprises at least one Other Active Ingredient; or (b) any combination of an Included Product and another pharmaceutical product that contains or comprises at least one Other Active Ingredient where such products are not formulated together but are sold together and invoiced as one product.

"Commercial Updates" means material information and developments with respect to the Company's Commercialization plans and prospects for the Included Products.

"Commercialization" means any and all activities, other than manufacturing, directed to the preparation for sale of, or sale of the Included Products, including activities related to marketing, promoting, distributing, and importing the Included Products, and interacting with Regulatory Agencies regarding any of the foregoing. When used as a verb, "to Commercialize" and "Commercializing" means to engage in Commercialization, and "Commercialized" has a corresponding meaning.

"Common Stock Purchase Agreement" means that certain Mirum Pharmaceuticals, Inc. Common Stock Purchase Agreement, dated as of the date hereof, by and between the Company and the investors party thereto.

"Company" has the meaning set forth in the first paragraph hereof.

"Compound" means maralixibat and any derivative thereof or modification thereto.

"Confidential Information" means, as it relates to the Company and any of its Affiliates, the Product Intellectual Property, and as it relates to the Company, any of its Affiliates, the Purchaser Agent and the Purchasers, all confidential business information, financial data and other like information and other proprietary information or material, together with such other information that either party identifies to the other as confidential or the nature of which or the circumstances of the disclosure of which could reasonably indicate that such information is confidential.

"Contracts" means, collectively, all rights of each Obligor under all leases, contracts and agreements to which such Obligor is now or hereafter a party, including, without limitation, all rights, privileges and powers under License Agreements, together with any and all extensions, modifications, amendments and renewals of such leases, contracts and agreements and all rights of such Obligor to receive moneys due or to become due thereunder or pursuant thereto and to amend, modify, terminate or exercise rights under such leases, contracts and agreements.

"Control" means the possession, directly or indirectly, of the power to direct or cause the direction of the management or policies of a Person, whether through the ability to exercise voting power, by contract or otherwise; provided that with respect to any Intellectual Property, "control" means that the applicable Persons owns or has a license to such item or right and has the ability to grant to a party a license, sublicense, or rights of access and use under such item or right without (a) violating the terms or conditions of any agreement or other arrangement between such Person and any Third Party in existence as of the time such party would be required hereunder to grant such license, sublicense, or rights of access and use, and (b) paying any consideration to any Third Party. "Controlling" and "Controlled" have meanings correlative thereto.

"Control Agreement" means, with respect to any deposit account, any securities account, commodity account, securities entitlement or commodity contract, an agreement, in form and substance reasonably satisfactory to the Purchaser Agent, among the Purchaser Agent, the financial institution or other Person at which such account is maintained or with which such entitlement or contract is carried and the Obligor maintaining such account, effective to grant "control" (as defined under the relevant Uniform Commercial Code) over such account to the Purchaser Agent.

"Covered Territory" means [...***...].

"Cumulative Purchaser Payments" means (a) if the Purchasers have made the First Payment, $50,000,000, (b) if the Purchasers have made the First Payment and the Second Payment, $115,000,000 and (c) if the Purchasers have made the First Payment, the Second Payment and the Third Payment, $150,000,000, plus, in all cases, any amounts funded as Additional Payments.

"Development" means all activities related to discovery, research, development, creation and prosecution of Intellectual Property, pre-clinical and other non-clinical testing, test method development and stability testing, toxicology, formulation, process development, manufacturing scale-up, qualification and validation, quality assurance/quality control, clinical studies, including Manufacturing in support thereof, statistical analysis and report writing, the preparation and submission of Drug Approval

Applications, regulatory affairs with respect to the foregoing and all other activities necessary or reasonably useful or otherwise requested or required by a Regulatory Agency as a condition or in support of obtaining or maintaining a Regulatory Approval. When used as a verb, "Develop" means to engage in Development.

"Disclosure Letter" means the Confidential Disclosure Letter, dated as of the Effective Date, and delivered by the Company to the Purchaser Agent.

"Dispute" has the meaning set forth in Section 3.11(d).

"Disqualified Equity Interests" means Equity Interests that, by their terms (or by the terms of any security or other Equity Interest into which they are convertible or for which they are exchangeable), or upon the happening of any event or condition, (a) mature (excluding any maturity as the result of an optional redemption by the issuer thereof) or are mandatorily redeemable, pursuant to a sinking fund obligation or otherwise, or are redeemable at the option of the holder thereof, in whole or in part, (b) are convertible into or exchangeable for (i) debt securities or (ii) any Equity Interests referred to in clause (a) above, (c) contain any repurchase obligation or (d) provide for required scheduled payments or the payment of cash dividends or distributions; provided that if such Equity Interests are issued pursuant to a plan for the benefit of the Company or any Subsidiary or their directors, officers, employees and/or consultants or by any such plan to directors, officers, employees or consultants of the Company or any Subsidiary, such Equity Interests shall not constitute Disqualified Equity Interests solely because they may be required to be repurchased by the Company or any Subsidiary in order to satisfy applicable statutory or regulatory obligations or as a result of such director, officer, employee or consultant's termination, death or disability.

"Domestic Subsidiary" means any direct or indirect Subsidiary that is organized under the laws of the United States, any state or commonwealth thereof, or the District of Columbia.

"Drug Approval Application" means a New Drug Application as defined in the FFDCA, or any corresponding foreign application.

"Effective Date" means December 8, 2020.

"Electronic Signature" means an electronic sound, symbol or process attached to, or associated with, a contract or other record and adopted by a Person with the intent to sign, authenticate or accept such contract or record.

"Eligible Assignee" is (i) a Purchaser, (ii) an Affiliate of a Purchaser or any fund or investment vehicle managed by the Purchaser or an Affiliate of a Purchaser or under common management with a Purchaser and (iii) any Person that, to the knowledge of the Purchaser Agent, is a "qualified institutional buyer" (as defined in Rule 144A under the Securities Act of 1933, as amended) or an "accredited investor" (as defined in Rule 501(a)(1), (2), (3) or (7)) with assets under management (together with its Affiliates) of at least $150,000,000, as determined by the Purchaser Agent in its good faith discretion; provided that, notwithstanding the foregoing, "Eligible Assignee" shall not include, unless a Put Option Event, or any event that with the giving of notice or passage of time would constitute a Put Option Event, has occurred and is continuing, (x) any operating company primarily engaged in the Development or Commercialization of pharmaceutical products, (y) any entity identified in the Disclosure Letter by and between the Company and the Purchaser Agent and any Affiliate thereof that is identifiable as such by name (or otherwise known to the Purchaser Agent to be an Affiliate) or (z) any stockholder activist hedge fund, in each case of clause (x), (y) and (z) as reasonably determined by the Purchaser Agent in its good faith discretion (any such person, a "Disqualified Person").

"Environmental Laws" means any and all federal, state, local, foreign and other applicable statutes, laws, regulations, ordinances, rules, judgments, orders, decrees, permits, concessions, grants, franchises, licenses, agreements or governmental restrictions relating to pollution and the protection of the environment or the release of any materials into the environment, including those related to hazardous substances or wastes, air emissions and discharges to waste or public systems.

"Equity Interests" means any and all shares, interests, participations or other equivalents (however designated) of equity interests of a corporation, any and all equivalent ownership interests in a Person other than a corporation (including, without limitation, partnership interests, membership interests and similar ownership interests), any and all warrants, rights or options to purchase or other arrangements or rights to acquire any of the foregoing, and all other ownership or profit interests in a Person (including partnership, member or trusts interests in such Person), in each case whether voting or non-voting and whether or not outstanding on any date of determination, but excluding any Permitted Convertible Notes.

"Excluded Accounts" means (a) any deposit account solely used for (i) funding payroll or segregating payroll taxes or funding other employee wage or benefit payments, (ii) segregating 401(k) contributions or contributions to an employee stock purchase plan and other health and benefit plans, in each case for payment in accordance with Applicable Laws and (iii) accounts pledged to secure letters of credit and bank guarantees to the extent constituting Permitted Liens under clause (m) thereof and (b) withholding tax and fiduciary trust accounts.

"Excluded Foreign Subsidiary" means each Foreign Subsidiary that is not a Material Foreign Subsidiary.

"Excluded Liabilities" has the meaning set forth in Section 2.04.

"Existing CMC Contract" means the CMC Contracts set forth on Exhibit F to the Disclosure Letter.

"Existing Supply Contract" means the Supply Contracts set forth on Exhibit F to the Disclosure Letter.

"Existing Upstream License Consents" means, with respect to each Existing Upstream License, a consent agreement in the form set forth on Exhibit E to the Disclosure Letter or in form and substance reasonably satisfactory to the Purchaser Agent.

"Existing Upstream Licenses" means (a) that certain License Agreement dated as of June 1, 2012 by and among Lumena Pharmaceuticals, Inc. and Pfizer Inc., (b) that certain License Agreement dated as of February 8, 2011 between Lumena Pharmaceuticals, Inc. and Satiogen Pharmaceuticals, Inc. and (c) that certain Assignment and License Agreement dated as of November 5, 2018 by and among the Company and Shire International Gmbh, in each case as amended from time to time.

"FATCA" means Sections 1471 through 1474 of the Code, as of the date of this Agreement (or any amended or successor version that is substantively comparable and not materially more onerous to comply with), any current or future regulations or official interpretations thereof, any agreements entered into pursuant to Section 1471(b)(1) of the Code and any fiscal or regulatory legislation, rules or practices adopted pursuant to any intergovernmental agreement, treaty or convention among Governmental Authorities and implementing such Sections of the Code.

"FCPA" has the meaning set forth in Section 3.22(b).

"FDA" means the United States Food and Drug Administration or any successor federal agency thereto.

"FDA Application Acceptance Date" means the date on which the FDA accepts for review the New Drug Application submitted by the Company for maralixibat as a treatment for pruritus due to Alagille Syndrome.

"FDA Approval Date" means the date on which the Company shall have delivered evidence satisfactory to the Purchaser Agent that the FDA has approved maralixibat as a treatment for Alagille Syndrome with a label consistent with the label included in the New Drug Application for maralixibat submitted to the FDA on November 11, 2020 and with no BLACK BOX warnings and with orphan exclusivity, as determined by the Purchaser Agent in its good faith business judgment.