Document:

EX-4.2

Table of Contents

 Exhibit 4.2 

EXECUTION  
 EIDOS
THERAPEUTICS, INC. 
 AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 Table of Contents 

 

									
	 	 	 	 	 	  	Page	 
	 1.
	 	DEFINITIONS	  	 	1	 
			
	 2.
	 	REGISTRATION RIGHTS	  	 	4	 
		 	2.1	 	Demand Registration	  	 	4	 
		 	2.2	 	Company Registration	  	 	5	 
		 	2.3	 	Underwriting Requirements	  	 	6	 
		 	2.4	 	Obligations of the Company	  	 	7	 
		 	2.5	 	Furnish Information	  	 	8	 
		 	2.6	 	Expenses of Registration	  	 	8	 
		 	2.7	 	Delay of Registration	  	 	9	 
		 	2.8	 	Indemnification	  	 	9	 
		 	2.9	 	Reports Under Exchange Act	  	 	11	 
		 	2.10	 	Limitations on Subsequent Registration Rights	  	 	12	 
		 	2.11	 	“Market Stand-off” Agreement	  	 	12	 
		 	2.12	 	Restrictions on Transfer	  	 	13	 
		 	2.13	 	Termination of Registration Rights	  	 	14	 
			
	 3.
	 	INFORMATION AND OBSERVER RIGHTS	  	 	14	 
		 	3.1	 	Delivery of Financial Statements	  	 	14	 
		 	3.2	 	Inspection	  	 	15	 
		 	3.3	 	Observer Rights	  	 	15	 
		 	3.4	 	Termination of Information and Observer Rights	  	 	16	 
		 	3.5	 	Confidentiality	  	 	16	 
			
	 4.
	 	ADDITIONAL COVENANTS	  	 	17	 
		 	4.1	 	Insurance	  	 	17	 
		 	4.2	 	Employee Agreements	  	 	17	 
		 	4.3	 	Employee Stock	  	 	17	 
		 	4.4	 	Board and Observer Matters	  	 	17	 
		 	4.5	 	Successor Indemnification	  	 	17	 
		 	4.6	 	Indemnification Matters	  	 	18	 
		 	4.7	 	Right to Conduct Activities	  	 	18	 

  
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 Table of Contents 

(continued) 
  

									
	 	 	 	 	 	  	Page	 
		 	 4.8
	 	 FCPA
	  	 	19	 
		 	4.9	 	Termination of Covenants	  	 	19	 
			
	 5.
	 	 RIGHTS OF FIRST REFUSAL
	  	 	20	 
		 	5.1	 	Subsequent Offerings	  	 	20	 
		 	5.2	 	Exercise of Rights	  	 	20	 
		 	5.3	 	Issuance of Equity Securities to Other Persons	  	 	20	 
		 	5.4	 	Sale Without Notice	  	 	21	 
		 	5.5	 	Termination and Waiver of Rights of First Refusal	  	 	21	 
		 	5.6	 	Assignment of Rights of First Refusal	  	 	21	 
		 	5.7	 	Excluded Securities	  	 	21	 
			
	 6.
	 	 MISCELLANEOUS
	  	 	21	 
		 	6.1	 	Successors and Assigns	  	 	21	 
		 	6.2	 	Governing Law	  	 	22	 
		 	6.3	 	Counterparts	  	 	22	 
		 	6.4	 	Titles and Subtitles	  	 	22	 
		 	6.5	 	Notices	  	 	22	 
		 	6.6	 	Amendments and Waivers	  	 	22	 
		 	6.7	 	Severability	  	 	23	 
		 	6.8	 	Aggregation of Stock	  	 	23	 
		 	6.9	 	Additional Investors	  	 	23	 
		 	6.10	 	Entire Agreement	  	 	23	 
		 	6.11	 	Dispute Resolution	  	 	24	 
		 	6.12	 	Delays or Omissions	  	 	24	 

 Schedule A – Investors 

Schedule B – Key Holders 

  
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 AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT 

THIS AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT (this “Agreement”), is made as of the 29th day of March, 2018, by and among Eidos
Therapeutics, Inc. a Delaware corporation (the “Company”), and each of the investors listed on Schedule A hereto, each of which is referred to in this Agreement as an “Investor”, and each of the
stockholders listed on Schedule B hereto, each of whom is referred to herein as a “Key Holder” and any Additional Purchaser (as defined in the Purchase Agreement) that becomes a party to this Agreement in accordance
with Section 5.9 hereof. 
 RECITALS 

WHEREAS, certain of the Investors (the “Existing Investors”) hold shares of the
Company’s Series Seed Preferred Stock and/or shares of Common Stock issued upon conversion thereof and possess registration rights, information rights, rights of first offer, and other rights pursuant to an Investors’ Rights Agreement
dated as of April 5, 2016 between the Company and such Investors (the “Prior Agreement”); and 

WHEREAS, the Existing Investors are holders of at least a majority of the Registrable Securities of the
Company (as defined in the Prior Agreement), and desire to amend and restate the Prior Agreement in its entirety and to accept the rights created pursuant to this Agreement in lieu of the rights granted to them under the Prior Agreement; and 

WHEREAS, certain of the Investors are parties to that certain Series B Preferred Stock Purchase Agreement
of even date herewith between the Company and certain of the Investors (the “Purchase Agreement”), under which certain of the Company’s and such Investors’ obligations are conditioned upon the execution and delivery
of this Agreement by such Investors, Existing Investors holding at least a majority of the Registrable Securities, and the Company;  

NOW, THEREFORE, the Existing Investors hereby agree that the Prior Agreement shall be
amended and restated, and the parties to this Agreement further agree as follows: 
 1.
DEFINITIONS. For purposes of this Agreement: 
 1.1
“Affiliate” means, with respect to any specified Person, any other Person who, directly or indirectly, controls, is controlled by, or is under common control with such Person, including without limitation any general partner,
managing member, officer or director of such Person or any venture capital, private equity or similar investment fund now or hereafter existing that is controlled by one or more general partners or managing members of, or shares the same management
company with, such Person; with respect to any Person that is an investment fund advised or sub-advised by a registered investment adviser, any other investment fund advised or
sub-advised by the same registered investment adviser. 
 1.2 “Common
Stock” means shares of the Company’s common stock, par value $0.001 per share. 

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 1.3 “Damages” means any loss, damage, claim or liability (joint or
several) to which a party hereto may become subject under the Securities Act, the Exchange Act, or other federal or state law, insofar as such loss, damage, claim or liability (or any action in respect thereof) arises out of or is based upon:
(i) any untrue statement or alleged untrue statement of a material fact contained in any registration statement of the Company, including any preliminary prospectus or final prospectus contained therein or any amendments or supplements thereto;
(ii) an omission or alleged omission to state therein a material fact required to be stated therein, or necessary to make the statements therein not misleading; or (iii) any violation or alleged violation by the indemnifying party (or any
of its agents or Affiliates) of the Securities Act, the Exchange Act, any state securities law, or any rule or regulation promulgated under the Securities Act, the Exchange Act, or any state securities law. 

1.4 “Derivative Securities” means any securities or rights convertible into, or exercisable or exchangeable for
(in each case, directly or indirectly), Common Stock, including options and warrants. 
 1.5 “Exchange Act”
means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 
 1.6
“Excluded Registration” means (i) a registration relating to the sale of securities to employees of the Company or a subsidiary pursuant to a stock option, stock purchase, or similar plan; (ii) a registration
relating to an SEC Rule 145 transaction; (iii) a registration on any form that does not include substantially the same information as would be required to be included in a registration statement covering the sale of the Registrable Securities;
or (iv) a registration in which the only Common Stock being registered is Common Stock issuable upon conversion of debt securities that are also being registered. 

1.7 “Form S-1” means such form under the Securities Act
as in effect on the date hereof or any successor registration form under the Securities Act subsequently adopted by the SEC. 
 1.8
“Form S-3” means such form under the Securities Act as in effect on the date hereof or any registration form under the Securities Act subsequently adopted by the SEC that
permits incorporation of substantial information by reference to other documents filed by the Company with the SEC. 
 1.9
“GAAP” means generally accepted accounting principles in the United States. 
 1.10
“Holder” means any holder of Registrable Securities who is a party to this Agreement. 
 1.11
“Immediate Family Member” means a child, stepchild, grandchild, parent, stepparent, grandparent, spouse, sibling, mother-in-law, father-in-law, son-in-law,
daughter-in-law, brother-in-law, or sister-in-law, including, adoptive relationships, of a natural person referred to herein. 

  
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 1.12 “Initiating Holders” means, collectively, Holders who
properly initiate a registration request under this Agreement. 
 1.13 “IPO” means the Company’s first
underwritten public offering of its Common Stock under the Securities Act. 
 1.14 “Major Investor” means any
Investor that, individually or together with such Investor’s Affiliates, holds at least 187,820 shares of Registrable Securities (as adjusted for any stock split, stock dividend, combination, or other recapitalization or reclassification
effected after the date hereof); provided that, for purposes of this Agreement, Blackwell Partners LLC—Series A (“Blackwell”) shall be considered a Major Investor; provided further, that any Investor that becomes a
Defaulting Purchaser (as defined in the Purchase Agreement) shall no longer be considered a Major Investor; 
 1.15
“Person” means any individual, corporation, partnership, trust, limited liability company, association or other entity. 

1.16 “Preferred Director” means any director of the Company that the holders of record of the Preferred Stock
are entitled to elect pursuant to the Company’s Certificate of Incorporation. 
 1.17 “Preferred Stock”
means shares of the Company’s Series Seed Preferred Stock and Series B Preferred Stock. 
 1.18 “Registrable
Securities” means (i) the Common Stock issuable or issued upon conversion of the Preferred Stock and (ii) any Common Stock, or any Common Stock issued or issuable (directly or indirectly) upon conversion and/or exercise of any other
securities of the Company, acquired by the Investors after the date hereof; excluding in all cases, however, any Registrable Securities sold by a Person in a transaction in which the applicable rights under this Agreement are not assigned pursuant
to Subsection 5.1, and excluding for purposes of Section 2 any shares for which registration rights have terminated pursuant to Subsection 2.13 of this Agreement. 

1.19 “Registrable Securities then outstanding” means the number of shares determined by adding the number of
shares of outstanding Common Stock that are Registrable Securities and the number of shares of Common Stock issuable (directly or indirectly) pursuant to then exercisable and/or convertible securities that are Registrable Securities. 

1.20 “Restricted Securities” means the securities of the Company required to be notated with the legend set
forth in Subsection 2.12(b) hereof. 
 1.21 “SEC” means the Securities and Exchange Commission. 

1.22 “SEC Rule 144” means Rule 144 promulgated by the SEC under the Securities Act. 

1.23 “SEC Rule 145” means Rule 145 promulgated by the SEC under the Securities Act. 

  
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 1.24 “Securities Act” means the Securities Act of 1933, as
amended, and the rules and regulations promulgated thereunder. 
 1.25 “Selling Expenses” means all
underwriting discounts, selling commissions, and stock transfer taxes applicable to the sale of Registrable Securities, and fees and disbursements of counsel for any Holder, except for the fees and disbursements of the Selling Holder Counsel borne
and paid by the Company as provided in Subsection 2.6. 
 1.26 “Series B Preferred Stock” means shares
of the Company’s Series B Preferred Stock, par value $0.001 per share. 
 1.27 “Series Seed Preferred
Stock” means shares of the Company’s Series Seed Preferred Stock, par value $0.001 per share. 
 2.
REGISTRATION RIGHTS. The Company covenants and agrees as follows: 

2.1 Demand Registration. 

(a) Form S-1 Demand. If at any time after the earlier of (i) three (3) years after
the date of this Agreement or (ii) one hundred eighty (180) days after the effective date of the registration statement for the IPO, the Company receives a request from Holders of a majority of the Registrable Securities then outstanding
that the Company file a Form S-1 registration statement with respect to a majority of the Registrable Securities then outstanding and if the anticipated aggregate offering price, net of Selling Expenses, would
exceed $10 million, then the Company shall (x) within ten (10) days after the date such request is given, give notice thereof (the “Demand Notice”) to all Holders other than the Initiating Holders; and
(y) as soon as practicable, and in any event within sixty (60) days after the date such request is given by the Initiating Holders, file a Form S-1 registration statement under the Securities Act
covering all Registrable Securities that the Initiating Holders requested to be registered and any additional Registrable Securities requested to be included in such registration by any other Holders, as specified by notice given by each such
Holder to the Company within twenty (20) days of the date the Demand Notice is given, and in each case, subject to the limitations of Subsections 2.1(c) and 2.3. 

(b) Form S-3 Demand. If at any time when it is eligible to use a Form S-3 registration statement, the Company receives a request from Holders of at least thirty percent (30%) of the Registrable Securities then outstanding that the Company file a Form
S-3 registration statement with respect to outstanding Registrable Securities of such Holders having an anticipated aggregate offering price, net of Selling Expenses, of at least $1 million, then the
Company shall (i) within ten (10) days after the date such request is given, give a Demand Notice to all Holders other than the Initiating Holders; and (ii) as soon as practicable, and in any event within forty-five (45) days
after the date such request is given by the Initiating Holders, file a Form S-3 registration statement under the Securities Act covering all Registrable Securities requested to be included in such registration
by any other Holders, as specified by notice given by each such Holder to the Company within twenty (20) days of the date the Demand Notice is given, and in each case, subject to the limitations of Subsections 2.1(c) and 2.3. 

  
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 (c) Notwithstanding the foregoing obligations, if the Company furnishes to Holders
requesting a registration pursuant to this Subsection 2.1 a certificate signed by the Company’s chief executive officer stating that in the good faith judgment of the Company’s Board of Directors it would be materially
detrimental to the Company and its stockholders for such registration statement to either become effective or remain effective for as long as such registration statement otherwise would be required to remain effective, because such action would
(i) materially interfere with a significant acquisition, corporate reorganization, or other similar transaction involving the Company; (ii) require premature disclosure of material information that the Company has a bona fide business
purpose for preserving as confidential; or (iii) render the Company unable to comply with requirements under the Securities Act or Exchange Act, then the Company shall have the right to defer taking action with respect to such filing for a
period of not more than ninety (90) days after the request of the Initiating Holders is given; provided, however, that the Company may not invoke this right more than once in any twelve (12) month period. 

(d) The Company shall not be obligated to effect, or to take any action to effect, any registration pursuant to
Subsection 2.1(a)(i) during the period that is thirty (30) days before the Company’s good faith estimate of the date of filing of, and ending on a date that is one hundred eighty (180) days after the effective date of, a
Company-initiated registration, provided that the Company is actively employing in good faith commercially reasonable efforts to cause such registration statement to become effective; (ii) after the Company has effected two registrations
pursuant to Subsection 2.1(a); or (iii) if the Initiating Holders propose to dispose of shares of Registrable Securities that may be immediately registered on Form S-3 pursuant to a request
made pursuant to Subsection 2.1(b). The Company shall not be obligated to effect, or to take any action to effect, any registration pursuant to Subsection 2.1(b) (i) during the period that is thirty (30) days before
the Company’s good faith estimate of the date of filing of, and ending on a date that is one hundred eighty (180) after the effective date of, a Company-initiated registration, provided that the Company is actively employing in good
faith commercially reasonable efforts to cause such registration statement to become effective; or (ii) if the Company has effected two registrations pursuant to Subsection 2.1(b) within the twelve (12) month period immediately
preceding the date of such request. A registration shall not be counted as “effected” for purposes of this Subsection 2.1(d) until such time as the applicable registration statement has been declared effective by the SEC,
unless the Initiating Holders withdraw their request for such registration, elect not to pay the registration expenses therefor, and forfeit their right to one demand registration statement pursuant to Subsection 2.6, in which case such
withdrawn registration statement shall be counted as “effected” for purposes of this Subsection 2.1(d). 
 2.2
Company Registration. If the Company proposes to register (including, for this purpose, a registration effected by the Company for stockholders other than the Holders) any of its securities under the Securities Act in connection with the
public offering of such securities solely for cash (other than in an Excluded Registration), the Company shall, at such time, promptly give each Holder notice of such registration. Upon the request of each Holder given within twenty (20) days after
such notice is given by the Company, the Company shall, subject to the provisions of Subsection 2.3, cause to be registered all of the Registrable Securities that each such Holder has requested to be included in such registration. The Company
shall have the right to terminate or withdraw any registration initiated by it under this Subsection 2.2 before the effective date of such registration, whether or not any Holder has elected to include Registrable Securities in such
registration. The expenses (other than Selling Expenses) of such withdrawn registration shall be borne by the Company in accordance with Subsection 2.6. 

  
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 2.3 Underwriting Requirements. 

(a) If, pursuant to Subsection 2.1, the Initiating Holders intend to distribute the Registrable Securities covered by
their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to Subsection 2.1, and the Company shall include such information in the Demand Notice. The underwriter(s) will be selected
by the Company and shall be reasonably acceptable to a majority in interest of the Initiating Holders. In such event, the right of any Holder to include such Holder’s Registrable Securities in such registration shall be conditioned upon such
Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting to the extent provided herein. All Holders proposing to distribute their securities through such underwriting shall
(together with the Company as provided in Subsection 2.4(e)) enter into an underwriting agreement in customary form with the underwriter(s) selected for such underwriting. Notwithstanding any other provision of this Subsection 2.3, if
the managing underwriter(s) advise(s) the Initiating Holders in writing that marketing factors require a limitation on the number of shares to be underwritten, then the Initiating Holders shall so advise all Holders of Registrable Securities that
otherwise would be underwritten pursuant hereto, and the number of Registrable Securities that may be included in the underwriting shall be allocated among such Holders of Registrable Securities, including the Initiating Holders, in proportion (as
nearly as practicable) to the number of Registrable Securities owned by each Holder or in such other proportion as shall mutually be agreed to by all such selling Holders; provided, however, that the number of Registrable Securities
held by the Holders to be included in such underwriting shall not be reduced unless all other securities are first entirely excluded from the underwriting. 

(b) In connection with any offering involving an underwriting of shares of the Company’s capital stock pursuant to Subsection
2.2, the Company shall not be required to include any of the Holders’ Registrable Securities in such underwriting unless the Holders accept the terms of the underwriting as agreed upon between the Company and its underwriters, and then only
in such quantity as the underwriters in their sole discretion determine will not jeopardize the success of the offering by the Company. If the total number of securities, including Registrable Securities, requested by stockholders to be included in
such offering exceeds the number of securities to be sold (other than by the Company) that the underwriters in their reasonable discretion determine is compatible with the success of the offering, then the Company shall be required to include in the
offering only that number of such securities, including Registrable Securities, which the underwriters and the Company in their sole discretion determine will not jeopardize the success of the offering. If the underwriters determine that less than
all of the Registrable Securities requested to be registered can be included in such offering, then the Registrable Securities that are included in such offering shall be allocated among the selling Holders in proportion (as nearly as practicable
to) the number of Registrable Securities owned by each selling Holder or in such other proportions as shall mutually be agreed to by all such selling Holders. Notwithstanding the foregoing, in no event shall (i) the number of Registrable
Securities included in the offering be reduced unless all other securities (other than securities to be sold by the Company) are first entirely excluded from the offering, or (ii) the 

  
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number of Registrable Securities included in the offering be reduced below thirty percent (30%) of the total number of securities included in such offering. For purposes of the provision in this
Subsection 2.3(b) concerning apportionment, for any selling Holder that is a partnership, limited liability company, or corporation, the partners, members, retired partners, retired members, stockholders, and Affiliates of such Holder, or the
estates and Immediate Family Members of any such partners, retired partners, members, and retired members and any trusts for the benefit of any of the foregoing Persons, shall be deemed to be a single “selling Holder,” and any pro rata
reduction with respect to such “selling Holder” shall be based upon the aggregate number of Registrable Securities owned by all Persons included in such “selling Holder,” as defined in this sentence. 

(c) For purposes of Subsection 2.1, a registration shall not be counted as “effected” if, as a result of an exercise
of the underwriter’s cutback provisions in Subsection 2.3(a), fewer than fifty percent (50%) of the total number of Registrable Securities that Holders have requested to be included in such registration statement are
actually included. 
 2.4 Obligations of the Company. Whenever required under this Section 2 to effect the registration
of any Registrable Securities, the Company shall, as expeditiously as reasonably possible: 
 (a) prepare and file with the SEC a
registration statement with respect to such Registrable Securities and use its commercially reasonable efforts to cause such registration statement to become effective and, upon the request of the Holders of a majority of the Registrable Securities
registered thereunder, keep such registration statement effective for a period of up to one hundred twenty (120) days or, if earlier, until the distribution contemplated in the registration statement has been completed; provided,
however, that such one hundred twenty (120) day period shall be extended for a period of time equal to the period the Holder refrains, at the request of an underwriter of Common Stock (or other securities) of the Company, from selling
any securities included in such registration; 
 (b) prepare and file with the SEC such amendments and supplements to such
registration statement, and the prospectus used in connection with such registration statement, as may be necessary to comply with the Securities Act in order to enable the disposition of all securities covered by such registration statement; 

(c) furnish to the selling Holders such numbers of copies of a prospectus, including a preliminary prospectus, as required by the
Securities Act, and such other documents as the Holders may reasonably request in order to facilitate their disposition of their Registrable Securities; 

(d) use its commercially reasonable efforts to register and qualify the securities covered by such registration statement under such
other securities or blue-sky laws of such jurisdictions as shall be reasonably requested by the selling Holders; provided that the Company shall not be required to qualify to do business or to file a
general consent to service of process in any such states or jurisdictions, unless the Company is already subject to service in such jurisdiction and except as may be required by the Securities Act; 

  
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 (e) in the event of any underwritten public offering, enter into and perform its
obligations under an underwriting agreement, in usual and customary form, with the underwriter(s) of such offering; 
 (f) use its
commercially reasonable efforts to cause all such Registrable Securities covered by such registration statement to be listed on a national securities exchange or trading system and each securities exchange and trading system (if any) on which
similar securities issued by the Company are then listed; 
 (g) provide a transfer agent and registrar for all Registrable
Securities registered pursuant to this Agreement and provide a CUSIP number for all such Registrable Securities, in each case not later than the effective date of such registration; 

(h) promptly make available for inspection by the selling Holders, any managing underwriter(s) participating in any disposition
pursuant to such registration statement, and any attorney or accountant or other agent retained by any such underwriter or selected by the selling Holders, all financial and other records, pertinent corporate documents, and properties of the
Company, and cause the Company’s officers, directors, employees, and independent accountants to supply all information reasonably requested by any such seller, underwriter, attorney, accountant, or agent, in each case, as necessary or advisable
to verify the accuracy of the information in such registration statement and to conduct appropriate due diligence in connection therewith; 

(i) notify each selling Holder, promptly after the Company receives notice thereof, of the time when such registration statement has
been declared effective or a supplement to any prospectus forming a part of such registration statement has been filed; and 
 (j)
after such registration statement becomes effective, notify each selling Holder of any request by the SEC that the Company amend or supplement such registration statement or prospectus. 

In addition, the Company shall ensure that, at all times after any registration statement covering a public offering of securities of the
Company under the Securities Act shall have become effective, its insider trading policy shall provide that the Company’s directors may implement a trading program under Rule 10b5-1 of the Exchange Act.

 2.5 Furnish Information. It shall be a condition precedent to the obligations of the Company to take any action pursuant to
this Section 2 with respect to the Registrable Securities of any selling Holder that such Holder shall furnish to the Company such information regarding itself, the Registrable Securities held by it, and the intended method of
disposition of such securities as is reasonably required to effect the registration of such Holder’s Registrable Securities. 
 2.6
Expenses of Registration. All expenses (other than Selling Expenses) incurred in connection with registrations, filings, or qualifications pursuant to Section 2, including all registration, filing, and qualification fees;
printers’ and accounting fees; fees and disbursements of counsel for the Company; and the reasonable fees and disbursements, not to exceed $25,000 per registration, of one counsel for the selling Holders (“Selling Holder
Counsel”), 

  
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shall be borne and paid by the Company; provided, however, that the Company shall not be required to pay for any expenses of any registration proceeding begun pursuant to
Subsection 2.1 if the registration request is subsequently withdrawn at the request of the Holders of a majority of the Registrable Securities to be registered (in which case all selling Holders shall bear such expenses pro rata based upon
the number of Registrable Securities that were to be included in the withdrawn registration), unless the Holders of a majority of the Registrable Securities agree to forfeit their right to one registration pursuant to Subsections 2.1(a) or
2.1(b), as the case may be; provided further that if, at the time of such withdrawal, the Holders shall have learned of a material adverse change in the condition, business, or prospects of the Company from that known to the Holders at
the time of their request and have withdrawn the request with reasonable promptness after learning of such information then the Holders shall not be required to pay any of such expenses and shall not forfeit their right to one registration pursuant
to Subsections 2.1(a) or 2.1(b). All Selling Expenses relating to Registrable Securities registered pursuant to this Section 2 shall be borne and paid by the Holders pro rata on the basis of the number of Registrable
Securities registered on their behalf. 
 2.7 Delay of Registration. No Holder shall have any right to obtain or seek an
injunction restraining or otherwise delaying any registration pursuant to this Agreement as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 2. 

2.8 Indemnification. If any Registrable Securities are included in a registration statement under this Section 2:

 (a) To the extent permitted by law, the Company will indemnify and hold harmless each selling Holder, and the partners, members,
officers, directors, and stockholders of each such Holder; legal counsel and accountants for each such Holder; any underwriter (as defined in the Securities Act) for each such Holder; and each Person, if any, who controls such Holder or underwriter
within the meaning of the Securities Act or the Exchange Act, against any Damages, and the Company will pay to each such Holder, underwriter, controlling Person, or other aforementioned Person any legal or other expenses reasonably incurred thereby
in connection with investigating or defending any claim or proceeding from which Damages may result, as such expenses are incurred; provided, however, that the indemnity agreement contained in this Subsection 2.8(a) shall not
apply to amounts paid in settlement of any such claim or proceeding if such settlement is effected without the consent of the Company, which consent shall not be unreasonably withheld, nor shall the Company be liable for any Damages to the extent
that they arise out of or are based upon actions or omissions made in reliance upon and in conformity with written information furnished by or on behalf of any such Holder, underwriter, controlling Person, or other aforementioned Person expressly
for use in connection with such registration. 
 (b) To the extent permitted by law, each selling Holder, severally and not jointly,
will indemnify and hold harmless the Company, and each of its directors, each of its officers who has signed the registration statement, each Person (if any), who controls the Company within the meaning of the Securities Act, legal counsel and
accountants for the Company, any underwriter (as defined in the Securities Act), any other Holder selling securities in such registration statement, and any controlling Person of any such underwriter or other

  
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Holder, against any Damages, in each case only to the extent that such Damages arise out of or are based upon actions or omissions made in reliance upon and in conformity with written information
furnished by or on behalf of such selling Holder expressly for use in connection with such registration; and each such selling Holder will pay to the Company and each other aforementioned Person any legal or other expenses reasonably incurred
thereby in connection with investigating or defending any claim or proceeding from which Damages may result, as such expenses are incurred; provided, however, that the indemnity agreement contained in this Subsection 2.8(b)
shall not apply to amounts paid in settlement of any such claim or proceeding if such settlement is effected without the consent of the Holder, which consent shall not be unreasonably withheld; and provided further that in no event
shall the aggregate amounts payable by any Holder by way of indemnity or contribution under Subsections 2.8(b) and 2.8(d) exceed the proceeds from the offering received by such Holder (net of any Selling Expenses paid by such Holder),
except in the case of fraud or willful misconduct by such Holder. 
 (c) Promptly after receipt by an indemnified party under this
Subsection 2.8 of notice of the commencement of any action (including any governmental action) for which a party may be entitled to indemnification hereunder, such indemnified party will, if a claim in respect thereof is to be made
against any indemnifying party under this Subsection 2.8, give the indemnifying party notice of the commencement thereof. The indemnifying party shall have the right to participate in such action and, to the extent the indemnifying party so
desires, participate jointly with any other indemnifying party to which notice has been given, and to assume the defense thereof with counsel mutually satisfactory to the parties; provided, however, that an indemnified party (together
with all other indemnified parties that may be represented without conflict by one counsel) shall have the right to retain one separate counsel, with the fees and expenses to be paid by the indemnifying party, if representation of such indemnified
party by the counsel retained by the indemnifying party would be inappropriate due to actual or potential differing interests between such indemnified party and any other party represented by such counsel in such action. 

(d) To provide for just and equitable contribution to joint liability under the Securities Act in any case in which either:
(i) any party otherwise entitled to indemnification hereunder makes a claim for indemnification pursuant to this Subsection 2.8 but it is judicially determined (by the entry of a final judgment or decree by a court of competent
jurisdiction and the expiration of time to appeal or the denial of the last right of appeal) that such indemnification may not be enforced in such case, notwithstanding the fact that this Subsection 2.8 provides for indemnification in such
case, or (ii) contribution under the Securities Act may be required on the part of any party hereto for which indemnification is provided under this Subsection 2.8, then, and in each such case, such parties will contribute to the
aggregate losses, claims, damages, liabilities, or expenses to which they may be subject (after contribution from others) in such proportion as is appropriate to reflect the relative fault of each of the indemnifying party and the indemnified party
in connection with the statements, omissions, or other actions that resulted in such loss, claim, damage, liability, or expense, as well as to reflect any other relevant equitable considerations. The relative fault of the indemnifying party and of
the indemnified party shall be determined by reference to, among other things, whether the untrue or allegedly untrue statement of a material fact, or the omission or alleged omission of a material fact, relates to information supplied by the
indemnifying party or by the indemnified party and the parties’ relative intent, knowledge, access to information, and opportunity to 

  
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correct or prevent such statement or omission; provided, however, that, in any such case (x) no Holder will be required to contribute any amount in excess of the public
offering price of all such Registrable Securities offered and sold by such Holder pursuant to such registration statement, and (y) no Person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act)
will be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation; and provided further that in no event shall a Holder’s liability pursuant to this Subsection 2.8(d), when combined
with the amounts paid or payable by such Holder pursuant to Subsection 2.8(b), exceed the proceeds from the offering received by such Holder (net of any Selling Expenses paid by such Holder), except in the case of willful misconduct or fraud
by such Holder. 
 (e) Unless otherwise superseded by an underwriting agreement entered into in connection with the underwritten
public offering, the obligations of the Company and Holders under this Subsection 2.8 shall survive the completion of any offering of Registrable Securities in a registration under this Section 2, and otherwise shall
survive the termination of this Agreement. 
 2.9 Reports Under Exchange Act. With a view to making available to the Holders
the benefits of SEC Rule 144 and any other rule or regulation of the SEC that may at any time permit a Holder to sell securities of the Company to the public without registration or pursuant to a registration on Form
S-3, the Company shall: 
 (a) make and keep available adequate current public information,
as those terms are understood and defined in SEC Rule 144, at all times after the effective date of the registration statement filed by the Company for the IPO; 

(b) use commercially reasonable efforts to file with the SEC in a timely manner all reports and other documents required of the
Company under the Securities Act and the Exchange Act (at any time after the Company has become subject to such reporting requirements); and 

(c) furnish to any Holder, so long as the Holder owns any Registrable Securities, forthwith upon request (i) to the extent
accurate, a written statement by the Company that it has complied with the reporting requirements of SEC Rule 144 (at any time after ninety (90) days after the effective date of the registration statement filed by the Company for the IPO), the
Securities Act, and the Exchange Act (at any time after the Company has become subject to such reporting requirements), or that it qualifies as a registrant whose securities may be resold pursuant to Form S-3
(at any time after the Company so qualifies); (ii) a copy of the most recent annual or quarterly report of the Company and such other reports and documents so filed by the Company; and (iii) such other information as may be reasonably requested
in availing any Holder of any rule or regulation of the SEC that permits the selling of any such securities without registration (at any time after the Company has become subject to the reporting requirements under the Exchange Act) or pursuant to
Form S-3 (at any time after the Company so qualifies to use such form). 

  
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 2.10 Limitations on Subsequent Registration Rights. From and after the date of this
Agreement, the Company shall not, without the prior written consent of the Holders of a majority of the Registrable Securities then outstanding, enter into any agreement with any holder or prospective holder of any securities of the Company that
would allow such holder or prospective holder (i) to include such securities in any registration unless, under the terms of such agreement, such holder or prospective holder may include such securities in any such registration only to
the extent that the inclusion of such securities will not reduce the number of the Registrable Securities of the Holders that are included; or (ii) to initiate a demand for registration of any securities held by such holder or
prospective holder; provided that this limitation shall not apply to any additional Investor who becomes a party to this Agreement in accordance with Subsection 5.9. 

2.11 “Market Stand-off” Agreement. Each Holder hereby agrees that it will not,
without the prior written consent of the managing underwriter, during the period commencing on the date of the final prospectus relating to the registration by the Company of shares of its Common Stock or any other equity securities under the
Securities Act on a registration statement on Form S-1 or Form S-3, and ending on the date specified by the Company and the managing underwriter (such period not to exceed one hundred eighty (180) days in the case of the IPO, or such
other period as may be requested by the Company or an underwriter to accommodate regulatory restrictions on (1) the publication or other distribution of research reports, and (2) analyst recommendations and opinions,
including, but not limited to, the restrictions contained in FINRA Rule 2711(f)(4) or NYSE Rule 472(f)(4), or any successor provisions or amendments thereto), (i) lend; offer; pledge; sell; contract to sell; sell any option or contract to purchase;
purchase any option or contract to sell; grant any option, right, or warrant to purchase; or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable
(directly or indirectly) for Common Stock, held immediately before the effective date of the registration statement for such offering or (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of
the economic consequences of ownership of such securities, whether any such transaction described in clause (i) or (ii) above is to be settled by delivery of Common Stock or other securities, in cash, or otherwise. The foregoing
provisions of this Subsection 2.11 shall apply only to the IPO, shall not apply to the sale of any shares to an underwriter pursuant to an underwriting agreement, or the transfer of any shares to any trust for the direct or indirect benefit
of the Holder or the immediate family of the Holder, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a
disposition for value, and shall be applicable to the Holders only if all officers, directors and stockholders individually owning more than one percent (1%) of the Company’s outstanding Common Stock are subject to the same restrictions. The
underwriters in connection with such registration are intended third-party beneficiaries of this Subsection 2.11 and shall have the right, power and authority to enforce the provisions hereof as though
they were a party hereto. Each Holder further agrees to execute such agreements as may be reasonably requested by the underwriters in connection with such registration that are consistent with this Subsection 2.11 or that are necessary to
give further effect thereto. The provisions of this Subsection 2.11 shall apply only to the Preferred Stock under this Agreement, and shall not apply to any shares the Company has purchased in the IPO or through the open market. 

  
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 2.12 Restrictions on Transfer. 

(a) The Preferred Stock and the Registrable Securities shall not be sold, pledged, or otherwise transferred, and the Company shall not
recognize and shall issue stop-transfer instructions to its transfer agent with respect to any such sale, pledge, or transfer, except upon the conditions specified in this Agreement, which conditions are intended to ensure compliance with the
provisions of the Securities Act. A transferring Holder will cause any proposed purchaser, pledgee, or transferee of the Preferred Stock and the Registrable Securities held by such Holder to agree to take and hold such securities subject to the
provisions and upon the conditions specified in this Agreement. 
 (b) Each certificate, instrument, or book entry representing
(i) the Preferred Stock, (ii) the Registrable Securities, and (iii) any other securities issued in respect of the securities referenced in clauses (i) and (ii), upon any stock split, stock dividend, recapitalization, merger,
consolidation, or similar event, shall (unless otherwise permitted by the provisions of Subsection 2.12(c)) be notated with a legend substantially in the following form: 

THE SECURITIES REPRESENTED HEREBY HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933. SUCH SHARES
MAY NOT BE SOLD, PLEDGED, OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR A VALID EXEMPTION FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SAID ACT. 

THE SECURITIES REPRESENTED HEREBY MAY BE TRANSFERRED ONLY IN ACCORDANCE WITH THE TERMS OF AN AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER,
A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY. 
 The Holders consent to the Company making a notation in its records and
giving instructions to any transfer agent of the Restricted Securities in order to implement the restrictions on transfer set forth in this Subsection 2.12. 

(c) The holder of such Restricted Securities, by acceptance of ownership thereof, agrees to comply in all respects with the provisions
of this Section 2. Before any proposed sale, pledge, or transfer of any Restricted Securities, unless there is in effect a registration statement under the Securities Act covering the proposed transaction, the Holder
thereof shall give notice to the Company of such Holder’s intention to effect such sale, pledge, or transfer. Each such notice shall describe the manner and circumstances of the proposed sale, pledge, or transfer in sufficient detail and, if
reasonably requested by the Company, shall be accompanied at such Holder’s expense by either (i) a written opinion of legal counsel who shall, and whose legal opinion shall, be reasonably satisfactory to the Company, addressed to the
Company, to the effect that the proposed transaction may be effected without registration under the Securities Act; (ii) a “no action” letter from the SEC to the effect that the proposed sale, pledge, or transfer of such Restricted
Securities without registration will not result in a recommendation by the staff of the SEC that action be taken with respect thereto; or (iii) any other evidence reasonably satisfactory to counsel to the Company to the effect that the proposed
sale, pledge, or transfer of the Restricted Securities may be effected without registration under the Securities Act, whereupon the Holder of such Restricted Securities shall be entitled to sell, 

  
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pledge, or transfer such Restricted Securities in accordance with the terms of the notice given by the Holder to the Company. The Company will not require such a legal opinion or “no
action” letter (x) in any transaction in compliance with SEC Rule 144; or (y) in any transaction in which such Holder distributes Restricted Securities to an Affiliate of such Holder; provided that each transferee agrees in
writing to be subject to the terms of this Subsection 2.12. Each certificate, instrument, or book entry representing the Restricted Securities transferred as above provided shall be notated with, except if such transfer is made pursuant to
SEC Rule 144, the appropriate restrictive legend set forth in Subsection 2.12(b), except that such certificate instrument, or book entry shall not be notated with such restrictive legend if, in the opinion of counsel for such Holder and the
Company, such legend is not required in order to establish compliance with any provisions of the Securities Act. For the avoidance of doubt, a customary arrangement in connection with the deposit of Registrable Securities in a non-margin custodial account shall not be deemed a sale, pledge or transfer for purposes of this Agreement so long as such registrable securities are in certificated form (it being understood that the Company may
require the exchange of any such certificated securities for book-entry shares upon the IPO). 
 2.13 Termination of Registration
Rights. The right of any Holder to request registration or inclusion of Registrable Securities in any registration pursuant to Subsections 2.1 or 2.2 shall terminate upon the earliest to occur of: 

(a) the closing of a Deemed Liquidation Event, as such term is defined in the Company’s Certificate of Incorporation; 

(b) such time as Rule 144 or another similar exemption under the Securities Act is available for the sale of all of such
Holder’s shares without limitation during a three-month period without registration; and 
 (c) the five (5) year
anniversary of the IPO. 
 3. INFORMATION AND OBSERVER
RIGHTS. 
 3.1 Delivery of Financial Statements. The Company shall deliver to each Major Investor: 

(a) as soon as practicable, but in any event within one hundred twenty (120) days after the end of each fiscal year of the Company
(i) a balance sheet as of the end of such year, (ii) statements of income and of cash flows for such year, and (iii) a statement of stockholders’ equity as of the end of such year, all prepared in accordance with GAAP; 

(b) as soon as practicable, but in any event within forty-five (45) days after the end of
each of the first three (3) quarters of each fiscal year of the Company, unaudited statements of income and cash flows for such fiscal quarter, and an unaudited balance sheet as of the end of such fiscal quarter, all prepared in accordance with
GAAP (except that such financial statements may (i) be subject to normal year-end audit adjustments; and (ii) not contain all notes thereto that may be required in accordance with GAAP); 

  
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 (c) as soon as practicable before the end of each fiscal year, a budget and business plan
for the next fiscal year, approved by the Board of Directors and prepared on a monthly basis, including balance sheets, income statements, and statements of cash flow for such months and, promptly after prepared, any other budgets or revised budgets
prepared by the Company; and 
 (d) such other information relating to the financial condition, business, prospects, or corporate
affairs of the Company as any Major Investor may from time to time reasonably request; provided, however, that the Company shall not be obligated under this Subsection 3.1 to provide information (i) that the Company
reasonably determines in good faith to be a trade secret or confidential information (unless covered by an enforceable confidentiality agreement, in a form acceptable to the Company, including Subsection 3.5 hereof); or (ii) the
disclosure of which would adversely affect the attorney-client privilege between the Company and its counsel. 
 If, for any period, the
Company has any subsidiary whose accounts are consolidated with those of the Company, then in respect of such period the financial statements delivered pursuant to the foregoing sections shall be the consolidated and consolidating financial
statements of the Company and all such consolidated subsidiaries. 
 Notwithstanding anything else in this Subsection 3.1 to the
contrary, the Company may cease providing the information set forth in this Subsection 3.1 during the period starting with the date sixty (60) days before the Company’s good-faith estimate of the date of filing of a registration
statement if it reasonably concludes it must do so to comply with the SEC rules applicable to such registration statement and related offering; provided that the Company’s covenants under this Subsection 3.1 shall be reinstated at
such time as the Company is no longer actively employing its commercially reasonable efforts to cause such registration statement to become effective. 

3.2 Inspection. The Company shall permit each Major Investor, at such Major Investor’s expense, to visit and inspect the
Company’s properties; examine its books of account and records; and discuss the Company’s affairs, finances, and accounts with its officers, during normal business hours of the Company as may be reasonably requested by the Major Investor;
provided, however, that the Company shall not be obligated pursuant to this Subsection 3.2 to provide access to any information that it reasonably and in good faith considers to be a trade secret or confidential information
(unless covered by an enforceable confidentiality agreement, in form acceptable to the Company, including Subsection 3.5 hereof) or the disclosure of which would adversely affect the attorney-client privilege between the Company and its
counsel. 
 3.3 Observer Rights. As long as RA Capital Healthcare Fund, L.P. (“RA Capital”) and its
Affiliates continue to own beneficially at least fifty percent (50%) of the shares of Series B Preferred Stock that RA Capital purchases at the Initial Closing (as defined in the Purchase Agreement) (or an equivalent amount of Common Stock issued
upon conversion thereof), which number is subject to appropriate adjustment for all stock splits, dividends, combinations, recapitalizations and the like, the Company shall invite a representative of RA Capital to attend all meetings of its Board of
Directors in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents, and other materials that it provides to its directors at the same time and in the same manner as provided to

  
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such directors; provided, however, that such representative shall agree to hold in confidence and trust and to act in a fiduciary manner with respect to all information so provided; and provided
further, that the Company reserves the right to withhold any information and to exclude such representative from any meeting or portion thereof if access to such information or attendance at such meeting could adversely affect the attorney-client
privilege between the Company and its counsel or result in disclosure of trade secrets or a conflict of interest, or if such Investor or its representative is a competitor of the Company. Notwithstanding the foregoing, if RA Capital becomes a
Defaulting Purchaser (as defined in the Purchase Agreement), it shall no longer have the right under this Section 3.3 to appoint an observer to the Board or to receive the information contemplated under this Section 3.3. 

3.4 Termination of Information and Observer Rights. The covenants set forth in Subsection 3.1, Subsection 3.2 and
Subsection 3.3 shall terminate and be of no further force or effect (i) immediately before the consummation of the IPO, or (ii) when the Company first becomes subject to the periodic reporting requirements of
Section 12(g) or 15(d) of the Exchange Act, or (iii) upon a Deemed Liquidation Event, as such term is defined in the Company’s Certificate of Incorporation, whichever event occurs first. 

3.5 Confidentiality. Each Investor agrees that such Investor will keep confidential and will not disclose, divulge, or use for
any purpose (other than to monitor its investment in the Company) any confidential information obtained from the Company pursuant to the terms of this Agreement (including notice of the Company’s intention to file a registration statement),
unless such confidential information (a) is known or becomes known to the public in general (other than as a result of a breach of this Subsection 3.5 by such Investor), (b) is or has been independently developed or conceived by
the Investor without use of the Company’s confidential information, or (c) is or has been made known or disclosed to the Investor by a third party without a breach of any obligation of confidentiality such third party may have to
the Company; provided, however, that an Investor may disclose confidential information (i) to its attorneys, accountants, consultants, advisors and other professionals to the extent necessary to obtain their services in
connection with monitoring its investment in the Company; (ii) to any prospective purchaser of any Registrable Securities from such Investor, if such prospective purchaser agrees to be bound by the provisions of this Subsection
3.5; (iii) to any Affiliate, partner, member, stockholder, current or prospective investor or wholly owned subsidiary of such Investor in the ordinary course of business, provided that such Investor informs such Person that such
information is confidential and directs such Person to maintain the confidentiality of such information; or (iv) as may otherwise be required by law, provided that the Investor promptly notifies the Company of such disclosure and
takes reasonable steps to minimize the extent of any such required disclosure. 
 3.6 Press Releases. The Company agrees not
to (a) issue any press release that uses the name of Investor or its Affiliates or (b) make any other statement communication to any third party (other than to its legal, accounting and financial advisors, and other than to
potential investors or acquirers under a duty of confidentiality) that uses the name of Investor or its Affiliates name without first allowing Investor to review and comment on such press release, statement or communication. 

  
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 3.7 Auditor Independence. The Company shall be reasonably responsive to requests
for information from the Investor relating to issues that may impact auditor independence rules applicable to the Investor. 
 4.
ADDITIONAL COVENANTS. 
 4.1 Insurance. The Company shall use its commercially
reasonable efforts to obtain, within ninety (90) days of the date hereof, from financially sound and reputable insurers Directors and Officers liability insurance, each in an amount and on terms and conditions satisfactory to the Board
of Directors, and will use commercially reasonable efforts to cause such insurance policies to be maintained until such time as the Board of Directors determines that such insurance should be discontinued. Notwithstanding any other provision of this
Section 4.1 to the contrary, for so long as a Preferred Director (as defined in the Company’s Certificate of Incorporation) is serving on the Board of Directors, the Company shall not cease to maintain a Directors and Officers
liability insurance policy in an amount of at least $2 million unless approved by at least one Preferred Director. 
 4.2
Employee Agreements. The Company will cause each person now or hereafter employed by it or by any subsidiary (or engaged by the Company or any subsidiary as a consultant/independent contractor) with access to confidential information and/or
trade secrets to enter into a nondisclosure and proprietary rights assignment agreement. 
 4.3 Employee Stock. Unless
otherwise approved by the Board of Directors, including at least one Preferred Director, all future employees and consultants of the Company who purchase, receive options to purchase, or receive awards of shares of the Company’s capital stock
after the date hereof shall be required to execute restricted stock or option agreements, as applicable, providing for (i) vesting of shares over a four (4) year period, with the first twenty-five percent (25%) of such shares
vesting following twelve (12) months of continued employment or service, and the remaining shares vesting in equal monthly installments over the following thirty-six (36) months, and (ii) a market stand-off
provision substantially similar to that in Subsection 2.11. In addition, unless otherwise approved by the Board of Directors, the Company shall retain a “right of first refusal” on employee transfers until the Company’s IPO and
shall have the right to repurchase unvested shares at cost upon termination of employment of a holder of restricted stock. 
 4.4
Board and Observer Matters. The Company shall reimburse its directors and board observers for all reasonable out-of-pocket travel expenses incurred in connection with attending meetings of the Board of Directors. 

4.5 Successor Indemnification. If the Company or any of its successors or assignees consolidates with or merges into any other
Person and is not the continuing or surviving corporation or entity of such consolidation or merger, then to the extent necessary, proper provision shall be made so that the successors and assignees of the Company assume the obligations of the
Company with respect to indemnification of members of the Board of Directors as in effect immediately before such transaction, whether such obligations are contained in the Company’s Bylaws, its Certificate of Incorporation, or elsewhere, as
the case may be. 

  
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 4.6 Indemnification Matters. The Company hereby acknowledges that one
(1) or more of the directors nominated to serve on the Board of Directors by the Investors (each a “Fund Director”) may have certain rights to indemnification, advancement of expenses and/or insurance provided by one or
more of the Investors and certain of their affiliates (collectively, the “Fund Indemnitors”). The Company hereby agrees (a) that it is the indemnitor of first resort (i.e., its obligations to any such
Fund Director are primary and any obligation of the Fund Indemnitors to advance expenses or to provide indemnification for the same expenses or liabilities incurred by such Fund Director are secondary), (b) that it shall be required to advance the
full amount of expenses incurred by such Fund Director and shall be liable for the full amount of all expenses, judgments, penalties, fines and amounts paid in settlement by or on behalf of any such Fund Director to the extent legally permitted and
as required by the Company’s Certificate of Incorporation or Bylaws of the Company (or any agreement between the Company and such Fund Director), without regard to any rights such Fund Director may have against the Fund Indemnitors, and,
(c) that it irrevocably waives, relinquishes and releases the Fund Indemnitors from any and all claims against the Fund Indemnitors for contribution, subrogation or any other recovery of any kind in respect thereof. The
Company further agrees that no advancement or payment by the Fund Indemnitors on behalf of any such Fund Director with respect to any claim for which such Fund Director has sought indemnification from the Company shall affect the foregoing and the
Fund Indemnitors shall have a right of contribution and/or be subrogated to the extent of such advancement or payment to all of the rights of recovery of such Fund Director against the Company. 

4.7 Right to Conduct Activities. The Company hereby agrees and acknowledges that BridgeBio Pharma LLC (together with its
Affiliates) (“BridgeBio”), RA Capital (together with its Affiliates), Viking Global Opportunities Illiquid Investments Sub-Master LP (together with its Affiliates, “Viking”), Amzak Health Investors, LLC (together
with its Affiliates, “Amzak”), Aisling Capital IV, LP (together with its Affiliates, “Aisling”) and Blackwell (together with its Affiliates) are each professional investment funds, and as such invest in numerous
portfolio companies, some of which may be deemed competitive with the Company’s business (as currently conducted or as currently proposed to be conducted). The Company hereby agrees that, to the extent permitted under applicable law, each of
BridgeBio, RA Capital (together with its Affiliates), Viking, Amzak, Aisling and Blackwell (together with its Affiliates) shall not be liable to the Company for any claim arising out of, or based upon, (i) the investment by any of
BridgeBio, RA Capital or its Affiliates, Viking, Amzak, Aisling or Blackwell or its Affiliates in any entity competitive with the Company, or (ii) actions taken by any partner, officer or other representative of any of BridgeBio, RA
Capital or its Affiliates, Viking, Amzak, Aisling or Blackwell or its Affiliates to assist any such competitive company, whether or not such action was taken as a member of the board of directors of such competitive company or otherwise, and whether
or not such action has a detrimental effect on the Company; provided, however, that the foregoing shall not relieve (x) any of the Investors from liability associated with the unauthorized disclosure of the Company’s confidential
information obtained pursuant to this Agreement, or (y) any director or officer of the Company from any liability associated with his or her fiduciary duties to the Company. 

  
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 4.8 Public Company Information. The Company understands and acknowledges that, in
the regular course of Viking’s and Amzak’s businesses, each of them and their Affiliates may invest in companies that have issued securities that are publicly traded (each, a “Public Company”). Accordingly, the Company
covenants and agrees that before providing material non-public information about a Public Company (“Public Company Information”) to Viking and/or Amzak, the Company will provide prior written notice describing the nature of such
information in reasonable detail. The Company shall not disclose Public Company Information to Viking, Amzak or their respective Affiliates without prior written authorization from Viking’s or Amzak’s respective legal and compliance
personnel. 
 4.9 FCPA. The Company represents that it shall not (and shall not permit any of its subsidiaries or affiliates
or any of its or their respective directors, officers, managers, employees, independent contractors, representatives or agents to) promise, authorize or make any payment to, or otherwise contribute any item of value to, directly or indirectly, to
any third party, including any Non-U.S. Official (as (as such term is defined in the U.S. Foreign Corrupt Practices Act of 1977, as amended (the “FCPA”)), in each case, in violation of the FCPA, the U.K. Bribery Act, or any other
applicable anti-bribery or anti-corruption law. The Company further represents that it shall (and shall cause each of its subsidiaries and affiliates to) cease all of its or their respective activities, as well as remediate any actions taken by the
Company, its subsidiaries or affiliates, or any of their respective directors, officers, managers, employees, independent contractors, representatives or agents in violation of the FCPA, the U.K. Bribery Act, or any other applicable anti-bribery or
anti-corruption law. The Company further represents that it shall (and shall cause each of its subsidiaries and affiliates to) maintain systems of internal controls (including, but not limited to, accounting systems, purchasing systems
and billing systems) to ensure compliance with the FCPA, the U.K. Bribery Act, or any other applicable anti-bribery or anti-corruption law. Upon request, the Company agrees to provide responsive information and/or certifications
concerning its compliance with applicable anti-corruption laws. The Company shall promptly notify each Investor if the Company becomes aware of any Enforcement Action (as defined in the Purchase Agreement). The Company shall,
and shall cause any direct or indirect subsidiary or entity controlled by it, whether now in existence or formed in the future, to comply with the FCPA. The Company shall use its best efforts to cause any direct or indirect subsidiary,
whether now in existence or formed in the future, to comply in all material respects with all applicable laws. 
 4.10 Termination
of Covenants. The covenants set forth in this Section 4, except for Subsections 4.5, 4.7 and 4.8 shall terminate and be of no further force or effect (i) immediately before the consummation of the IPO
or (ii) when the Company first becomes subject to the periodic reporting requirements of Section 12(g) or 15(d) of the Exchange Act, or (iii) upon a Deemed Liquidation Event, as such term is defined in the
Company’s Certificate of Incorporation, whichever event occurs first. 

  
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 5. RIGHTS OF FIRST REFUSAL.

 5.1 Subsequent Offerings. Subject to applicable securities laws, each Investor shall have a right of first refusal to
purchase its pro rata share of all Equity Securities, as defined below, that the Company may, from time to time, propose to sell and issue after the date of this Agreement, other than the Equity Securities excluded by Section 5.7
hereof. Each Investor’s pro rata share is equal to the ratio of (a) the number of shares of the Company’s Common Stock (including all shares of Common Stock issuable or issued upon conversion of the shares or upon the
exercise of outstanding warrants or options) of which such Investor is deemed to be a holder immediately prior to the issuance of such Equity Securities to (b) the total number of shares of the Company’s outstanding Common Stock
(including all shares of Common Stock issued or issuable upon conversion of the shares or upon the exercise of any outstanding warrants or options) immediately prior to the issuance of the Equity Securities. The term “Equity
Securities” shall mean (i) any Common Stock, Preferred Stock or other equity security of the Company, (ii) any security convertible into or exercisable or exchangeable for, with or without consideration, any Common
Stock, Preferred Stock or other equity security (including any option to purchase such a convertible security), (iii) any equity security carrying any warrant or right to subscribe to or purchase any Common Stock, Preferred Stock or
other security or (iv) any such warrant or right. 
 5.2 Exercise of Rights. If the Company proposes to issue any Equity
Securities, it shall give each Investor written notice of its intention, describing the Equity Securities, the price and the terms and conditions upon which the Company proposes to issue the same. Each Investor shall have fifteen
(15) days from the giving of such notice to agree to purchase up to that portion of such Equity Securities that equals the proportion that the number of shares of Registrable Securities issued and held by such Investor (assuming full
conversion, exercise and/or exchange of all convertible, exercisable and/or exchangeable securities then outstanding) bears to the total number of shares of Common Stock of the Company then outstanding (assuming full conversion, exercise and/or
exchange of all convertible, exercisable and/or exchangeable securities then outstanding) for the price and upon the terms and conditions specified in the notice by giving written notice to the Company and stating therein the quantity of Equity
Securities to be purchased. Notwithstanding the foregoing, the Company shall not be required to offer or sell such Equity Securities to any Investor who would cause the Company to be in violation of applicable federal securities laws by virtue of
such offer or sale. 
 5.3 Issuance of Equity Securities to Other Persons. If not all of the Investors elect to purchase all the
Equity Securities available to them pursuant to Section 5.2, then the Company shall promptly notify in writing the Investors who do so elect to purchase all the Equity Securities available to them pursuant to Section 5.2 (a
“Fully-Exercising Investor”) and shall offer such Fully-Exercising Investors the right to acquire such number of unsubscribed shares that is equal to the proportion that the number of shares of Registrable Securities issued and held
by such Fully-Exercising Investor bears to the total number of shares of Common Stock issued and held, or issuable upon conversion of the Preferred Stock then held, by all Fully-Exercising Investors who wish to purchase some of the unsubscribed
shares. The Fully-Exercising Investors shall have five (5) days after receipt of such notice to notify the Company of its election to purchase all or a portion thereof of the unsubscribed shares. The Company shall have ninety
(90) days thereafter to sell the Equity Securities in respect of which the Investor’s rights were not exercised, at a price and upon general terms and conditions not materially more favorable to the purchasers thereof than specified
in the Company’s notice to the Investors pursuant to Section 5.2 hereof. If the Company has not sold such Equity Securities within ninety (90) days of the notice provided pursuant to Section 5.2, the Company
shall not thereafter issue or sell any Equity Securities, without first offering such securities to the Investors in the manner provided above. 

  
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 5.4 Sale Without Notice. In lieu of giving notice to the Investors prior to the
issuance of Equity Securities as provided in Section 5.2, the Company may elect to give notice to the Investors within thirty (30) days after the issuance of Equity Securities. Such notice shall describe the type, price and
terms of the Equity Securities. Each Investor shall have twenty (20) days from the date of receipt of such notice to elect to purchase up to the number of shares that would, if purchased by such Investor, maintain such Investor’s
pro rata share (as set forth in Section 5.1) of the Company’s equity securities after giving effect to all such purchases. The closing of such sale shall occur within sixty (60) days of the date of notice to the
Investors. 
 5.5 Termination and Waiver of Rights of First Refusal. The rights of first refusal established by this
Section 5 shall not apply to, and shall terminate upon the earlier of (i) the effective date of the registration statement pertaining to the IPO or (ii) the closing of a Deemed Liquidation Event (as defined in the
Company’s Certificate of Incorporation). Notwithstanding Section 6.6 hereof, the rights of first refusal established by this Section 5 may be amended, or any provision waived with and only with the written
consent of the Company and the Investors holding a majority of the Registrable Securities held by all Investors, or as permitted by Section 6.6. 

5.6 Assignment of Rights of First Refusal. The rights of first refusal of each Major Investor under this Section 5
may be assigned to the same parties, subject to the same restrictions as any transfer of registration rights pursuant to Section 2.12. 

5.7 Excluded Securities. The rights of first refusal established by this Section 5 shall have no application to any
Equity Securities that are Exempted Securities (as defined in the Company’s Certificate of Incorporation) or any Equity Securities issued by the Company pursuant to the terms of Section 1.3 of the Purchase Agreement. 

6. MISCELLANEOUS. 

6.1 Successors and Assigns. The rights under this Agreement may be assigned (but only with all related obligations) by a Holder
to a transferee of Registrable Securities that (i) is an Affiliate of a Holder; (ii) is a Holder’s Immediate Family Member or trust for the benefit of an individual Holder or one or more of such Holder’s Immediate
Family Members; or (iii) after such transfer, holds at least 100,000 shares of Registrable Securities (subject to appropriate adjustment for stock splits, stock dividends, combinations, and other recapitalizations); provided,
however, that (x) the Company is, within a reasonable time after such transfer, furnished with written notice of the name and address of such transferee and the Registrable Securities with respect to which such rights are being
transferred; and (y) such transferee agrees in a written instrument delivered to the Company to be bound by and subject to the terms and conditions of this Agreement, including the provisions of Subsection 2.11. For the purposes
of determining the number of shares of Registrable Securities held by a transferee, the holdings of a transferee (1) that is an Affiliate or stockholder of a Holder; (2) who is a Holder’s Immediate Family Member; or
(3) that is a trust for the benefit of an individual Holder or such Holder’s Immediate Family Member shall be aggregated together and with those of the 

  
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transferring Holder; provided further that all transferees who would not qualify individually for assignment of rights shall have a single attorney-in-fact for the purpose of
exercising any rights, receiving notices, or taking any action under this Agreement. The terms and conditions of this Agreement inure to the benefit of and are binding upon the respective successors and permitted assignees of the parties. Nothing in
this Agreement, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and permitted assignees any rights, remedies, obligations or liabilities under or by reason of this Agreement,
except as expressly provided herein. 
 6.2 Governing Law. This Agreement shall be governed by the internal law of the State
of Delaware. 
 6.3 Counterparts. This Agreement may be executed in two (2) or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of
2000, e.g., www.docusign.com) or other transmission method and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

6.4 Titles and Subtitles. The titles and subtitles used in this Agreement are for convenience only and are not to be considered
in construing or interpreting this Agreement. 
 6.5 Notices. All notices and other communications given or made pursuant to
this Agreement shall be in writing and shall be deemed effectively given upon the earlier of actual receipt or (i) personal delivery to the party to be notified; (ii) when sent, if sent by electronic mail or facsimile during
the recipient’s normal business hours, and if not sent during normal business hours, then on the recipient’s next business day; (iii) five (5) days after having been sent by registered or certified mail, return receipt
requested, postage prepaid; or (iv) one (1) business day after the business day of deposit with a nationally recognized overnight courier, freight prepaid, specifying next-day delivery, with written verification of receipt. All
communications shall be sent to the respective parties at their addresses as set forth on Schedule A hereto, or to the principal office of the Company and to the attention of the Chief Executive Officer, in the case of the
Company, or to such email address, facsimile number, or address as subsequently modified by written notice given in accordance with this Subsection 6.5. If notice is given to the Company, a copy shall also be sent to Goodwin Procter, LLP,
Three Embarcadero Center, 28th Floor, San Francisco, CA 94111, Attn: Maggie Wong. 

6.6 Amendments and Waivers. Any term of this Agreement may be amended and the observance of any term of this Agreement may be
waived (either generally or in a particular instance, and either retroactively or prospectively) only with the written consent of the Company and the holders of a majority of the Registrable Securities then outstanding; provided that the
Company may in its sole discretion waive compliance with Subsection 2.12(c) (and the Company’s failure to object promptly in writing after notification of a proposed assignment allegedly in violation of Subsection 2.12(c) shall be
deemed to be a waiver); provided further, that Subsection 1.19 of this Agreement shall not be amended to exclude Blackwell without the written consent of Blackwell; provided further, that Subsections 3.3 and
4.4 shall not be amended or waived without the written consent of RA Capital so long as (x) RA 

  
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Capital and its Affiliates continue to own beneficially at least fifty percent (50%) of the shares of Series B Preferred Stock that RA Capital purchases at the Initial Closing (or an equivalent
amount of Common Stock issued upon conversion thereof) and (y) RA Capital has not become a Defaulting Purchaser (as defined in the Purchase Agreement); provided further, that Subsection 4.7 shall not be amended or waived
without the written consent of BridgeBio, RA Capital, Viking, Amzak, Aisling and Blackwell; and provided further that any provision hereof may be waived by any waiving party on such party’s own behalf, without the consent of any
other party. Notwithstanding the foregoing, (a) this Agreement may not be amended or terminated and the observance of any term hereof may not be waived with respect to any Investor without the written consent of such Investor, unless
such amendment, termination, or waiver applies to all Investors in the same fashion and (b) in the event the rights under Section 5 are waived with respect to an offering of Equity Securities without an Investor’s prior
written consent and any party that participated in waiving such rights actually purchases Equity Securities in such offering, the Company shall grant to any such non-waiving Investor the right to purchase, in a subsequent closing of such issuance on
substantially the same terms and conditions, the same percentage of its full pro rata share of such Equity Securities as the highest percentage of any such purchasing waiving party. The Company shall give prompt notice of any amendment or
termination hereof or waiver hereunder to any party hereto that did not consent in writing to such amendment, termination, or waiver. Any amendment, termination, or waiver effected in accordance with this Subsection 6.6 shall be binding on
all parties hereto, regardless of whether any such party has consented thereto. No waivers of or exceptions to any term, condition, or provision of this Agreement, in any one or more instances, shall be deemed to be or construed as a further or
continuing waiver of any such term, condition, or provision. 
 6.7 Severability. In case any one or more of the provisions
contained in this Agreement is for any reason held to be invalid, illegal or unenforceable in any respect, such invalidity, illegality, or unenforceability shall not affect any other provision of this Agreement, and such invalid, illegal, or
unenforceable provision shall be reformed and construed so that it will be valid, legal, and enforceable to the maximum extent permitted by law. 

6.8 Aggregation of Stock. All shares of Registrable Securities held or acquired by Affiliates shall be aggregated together for
the purpose of determining the availability of any rights under this Agreement and such Affiliated persons may apportion such rights as among themselves in any manner they deem appropriate. 

6.9 Additional Investors. Notwithstanding anything to the contrary contained herein, if the Company issues additional shares of
the Company’s Series B Preferred Stock after the date hereof, any purchaser of such shares of Series B Preferred Stock may become a party to this Agreement by executing and delivering an additional counterpart signature page to this Agreement,
and thereafter shall be deemed an “Investor” for all purposes hereunder. No action or consent by the Investors shall be required for such joinder to this Agreement by such additional Investor, so long as such additional Investor has agreed
in writing to be bound by all of the obligations as an “Investor” hereunder. 
 6.10 Entire Agreement. This
Agreement (including any Schedules and Exhibits hereto) constitutes the full and entire understanding and agreement among the parties with respect to the subject matter hereof, and any other written or oral agreement relating to the subject matter
hereof existing between the parties is expressly canceled. Upon the effectiveness of this Agreement, the Prior Agreement shall be deemed amended and restated and superseded and replaced in its entirety by this Agreement, and shall be of no further
force or effect. 

  
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 6.11 Dispute Resolution. Any unresolved controversy or claim arising out of or
relating to this Agreement, except as (i) otherwise provided in this Agreement, or (ii) any such controversies or claims arising out of either party’s intellectual property rights for which a provisional remedy or
equitable relief is sought, shall be submitted to arbitration by one arbitrator mutually agreed upon by the parties, and if no agreement can be reached within thirty (30) days after names of potential arbitrators have been proposed by
the American Arbitration Association (the “AAA”), then by one arbitrator having reasonable experience in corporate finance transactions of the type provided for in this Agreement and who is chosen by the AAA. The arbitration
shall take place in Palo Alto, California, in accordance with the AAA rules then in effect, and judgment upon any award rendered in such arbitration will be binding and may be entered in any court having jurisdiction thereof. There shall be limited
discovery prior to the arbitration hearing as follows: (a) exchange of witness lists and copies of documentary evidence and documents relating to or arising out of the issues to be arbitrated, (b) depositions of all party
witnesses and (c) such other depositions as may be allowed by the arbitrators upon a showing of good cause. Depositions shall be conducted in accordance with the California Code of Civil Procedure, the arbitrator shall be required to
provide in writing to the parties the basis for the award or order of such arbitrator, and a court reporter shall record all hearings, with such record constituting the official transcript of such proceedings. 

6.12 Delays or Omissions. No delay or omission to exercise any right, power, or remedy accruing to any party under this
Agreement, upon any breach or default of any other party under this Agreement, shall impair any such right, power, or remedy of such nonbreaching or nondefaulting party, nor shall it be construed to be a waiver of or acquiescence to any such breach
or default, or to any similar breach or default thereafter occurring, nor shall any waiver of any single breach or default be deemed a waiver of any other breach or default theretofore or thereafter occurring. All remedies, whether under this
Agreement or by law or otherwise afforded to any party, shall be cumulative and not alternative. 

  
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 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	EIDOS THERAPEUTICS, INC.
		
	By:	 	/s/ Neil Kumar

 
			
	Name:	 	Neil Kumar

 
			
	Title:	 	Chief Executive Officer

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	KEY HOLDERS:
		
	Signature:	 	/s/ Isabella Graef

 
			
	Name:	 	Isabella Graef

  

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Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	KEY HOLDERS:
		
	Signature:	 	/s/ Mamoun Alhamadsheh

 
			
	Name:	 	Mamoun Alhamadsheh

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	KEY HOLDERS:
		
	Signature:	 	/s/ Christine Siu

 
			
	Name:	 	Christine Siu

  

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INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	KEY HOLDERS:
		
	Signature:	 	/s/ Uma Sinha

 
			
	Name:	 	Uma Sinha

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	KEY HOLDERS:
	
	 Jonathan C Fox and Suzanne Markel-Fox,
Co-Trustees of the Fox Family Trust Dated
 17 Dec 2014

		
	Signature:	 	/s/ Jonathan C Fox

 
			
	Name:	 	Jonathan C Fox

 
			
	Title:	 	Trustee, Fox Family Trust

  

			
		
	Signature:	 	/s/ Suzanne Markel-Fox

 
			
	Name:	 	Suzanne Markel-Fox

 
			
	Title:	 	Trustee, Fox Family Trust

  

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INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	INVESTORS:
	
	BRIDGEBIO PHARMA LLC
		
	By:	 	/s/ Neil Kumar

 
			
	Name:	 	Neil Kumar

 
			
	Title:	 	Chief Executive Officer

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	INVESTORS:
	
	    RA CAPITAL HEALTHCARE FUND, L.P.
		
	        By:	 	RA Capital Management, LLC

 
			
	        Its:	 	General Partner

  

			
	        By:	 	/s/ Rajeev Shah

 
			
	        Name:	 	Rajeev Shah

 
			
	        Title:	 	Authorized Signatory

 
			
		
	        Address:	 	RA Capital Management, LLC
		 	20 Park Plaza
		 	Suite 1200
		 	Boston, MA 02116
		 	Attn: Rajeev Shah

  

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INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	        INVESTORS:
	
	BLACKWELL PARTNERS LLC – SERIES A
		
	By:	 	/s/ Abayomi A. Adigun

 
			
	Name:	 	Abayomi A. Adigun
	Title:	 	Investment Manager
		 	DUMAC, Inc.
		 	Authorized Signatory

  

			
	By:	 	/s/ Jannine M. Lall

 
			
	Name:	 	Jannine M. Lall
	Title:	 	Controller
		 	DUMAC, Inc.
		 	Authorized Signatory

  

			
	Address:	 	Blackwell Partners LLC – Series A

 
			
		 	280 S. Mangum Street
		 	Suite 210
		 	Durham, NC 27701
		 	Attn: Jannine Lall

  

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INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	        INVESTORS:
	
	AISLING CAPITAL IV, LP
		
	By:	 	/s/ Robert Wenzel

 
			
	Name:	 	Robert Wenzel
	Title:	 	CFO
	
	Aisling Capital IV, L.P.
	888 Seventh Avenue, 12th Floor
	New York, NY 10106
	 Attn: Drew Schiff
 Fax: 212 651
6379

	
	and
	
	Aisling Capital IV, L.P.
	888 Seventh Avenue, 12th Floor
	New York, NY 10106
	Attn: Chief Financial Officer
	Fax: 212 651 6379
	
	With a required copy to:
	
	McDermott Will & Emery LLP
	340 Madison Avenue
	New York, NY 10173-1922
	Attn: Todd Finger
	Fax: 212 547 5444

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	  INVESTORS:
	
	VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP
		
	    By:	 	Viking Global Opportunities Portfolio
	    GP LLC, its general partner

  

			
		
	    By:	 	/s/ Matthew Bloom

 
			
	    Name:	 	Matthew Bloom
	    Title:	 	Authorized Signatory

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	    INVESTORS:
	
	AMZAK HEALTH INVESTORS, LLC
		
	    By:	 	/s/ Anders Hove

 
			
	    Name:	 	Anders Hove
	    Title:	 	Manager

  

			
	    Address:	 	980 North Federal Highway
		 	Suite 315
		 	Boca Raton
		 	FL 33432
		 	Attn: Anders Hove

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

					
	INVESTORS:
		
		 	The Board of Trustees of Leland Stanford Junior University
		
		 	 /s/ Sabrina Liang

		 	Name:	 	Sabrina Liang
		 	Title:	 	 Director, School and Department

Funds

  

			
	        Address:	 	Stanford management Company
		 	635 Knight Way
		 	Stanford, CA 94305-7297

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	    INVESTORS:
	
	CORMORANT PRIVATE HEALTHCARE FUND I, LP
		
	    By:	 	Cormorant Private Healthcare GP, LLC
		
	    By:	 	/s/ Bihua Chen
		 	Bihua Chen, Managing Member of the GP

 
			
		
	    Address:	 	200 Clarendon Street
		 	52nd Floor
		 	Boston, MA 02116

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	    INVESTORS:
	
	CORMORANT GLOBAL HEALTHCARE MASTER FUND, LP
		
	        By:	 	Cormorant Private Healthcare GP, LLC
		
	        By:	 	/s/ Bihua Chen
		 	Bihua Chen, Managing Member of the GP

 
			
		
	    Address:	 	200 Clarendon Street
		 	52nd Floor
		 	Boston, MA 02116

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	    INVESTORS:
	
	CRMA SPV, L.P.
		
	        By:	 	Cormorant Asset Management, LLC
		
	        By:	 	/s/ Bihua Chen

 
			
	        Name:	 	Bihua Chen, CEO/CIO

 
			
	        Its:	 	Attorney-in-Fact

 
			
		
	        Address:	 	PO Box 309
		 	Ugland House
		 	Grand Cayman KY1-1104
		 	Cayman Islands

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	    INVESTORS:
	
	PERCEPTIVE LIFE SCIENCES MASTER FUND LTD.
		
	        By:	 	/s/ James H Mannix

 
			
	        Name:	 	James H Mannix

 
			
	        Title:	 	COO

 
			
		
	        Address:	 	51 Astor place 10th Floor
		 	New York NY. 10003

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	INVESTORS:

 
			
	
	JANUS HENDERSON GLOBAL LIFE SCIENCES FUND
	
	     JANUS CAPITAL MANAGEMENT, LLC

    as investment advisor for Janus Henderson

    Global Life Sciences Fund

 
			
		
	    By:	 	/s/ Enrique Chang

 
			
	    Name:	 	Enrique Chang

 
			
	    Title:	 	Authorized Signatory

 
			
		
	    Address:	 	c/o Janus Capital Management, LLC
		 	151 Detroit Street
		 	Denver CO 80206
		 	Attn: Legal Department, 4th Floor

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 IN WITNESS WHEREOF, the
parties have executed this AGREEMENT as of the date first written above. 
  

			
	INVESTORS:
	
	JANUS HENDERSON CAPITAL FUNDS PLC ON BEHALF OF ITS SERIES JANUS HENDERSON GLOBAL LIFE SCIENCES FUND
	
	     JANUS CAPITAL MANAGEMENT, LLC

    as investment advisor for Janus Henderson

    Capital Funds PLC on behalf of its series

    Janus Henderson Global Life Sciences 
Fund

 
			
		
	    By:	 	/s/ Enrique Chang

 
			
	    Name:	 	Enrique Chang

 
			
	    Title:	 	Authorized Signatory

 
			
		
	    Address:	 	c/o Janus Capital Management, LLC
		 	151 Detroit Street
		 	Denver CO 80206
		 	Attn: Legal Department, 4th Floor

  

SIGNATURE PAGE TO AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT 

Table of Contents

 SCHEDULE A 

INVESTORS 

BRIDGEBIO PHARMA LLC 

Address: 421 Kipling Street, Palo Alto, CA 94301 
 Phone Number

 Fax Number 
 Email: nk@bridgebio.com 

THE BOARD OF TRUSTEES OF LELAND STANFORD
JUNIOR UNIVERSITY 
 Stanford Management Company 

635 Knight Way 
 Stanford, CA 94305 

GERALD CRABTREE 
 Address

 Phone Number 
 Fax Number 

Email 
 RA CAPITAL HEALTHCARE
FUND, L.P. 
 20 Park Plaza, Suite 1200 

Boston, MA 02116 
 Attn: Rajeev Shah 

Email: rshah@racap.com 
 BLACKWELL
PARTNERS LLC—SERIES A 
 280 S. Mangum Street, Suite 210 

Durham, NC 27701 
 Attn: Jannine Lall 

Email: legal@dumac.duke.edu 
 JANUS
HENDERSON GLOBAL LIFE SCIENCES FUND and 

JANUS HENDERSON CAPITAL FUNDS PLC ON BEHALF OF
ITS SERIES JANUS HENDERSON GLOBAL LIFE SCIENCES 

c/o Janus Capital Management, LLC 
 151 Detroit Street 

Denver CO 80206 
 Attn: Legal Department, 4th Floor 

VIKING GLOBAL OPPORTUNITIES ILLIQUID INVESTMENTS SUB-MASTER LP 
 c/o Viking Global Investors LP 

55 Railroad Avenue 
 Greenwich, CT 06830 

Attn: General Counsel 
 Email:
legalnotices@vikingglobal.com 

Table of Contents

 PERCEPTIVE LIFE SCIENCES MASTER
FUND LTD. 
 51 Astor Place, 10th Floor 
 New
York, NY 10003 
 AISLING CAPITAL IV, L.P. 

888 Seventh Avenue, 12th Floor 
 New York, NY 10106 

Attn: Drew Schiff 
 Fax: 212 651 6379 

With a required copy to: 
 McDermott Will & Emery LLP

 340 Madison Avenue 
 New York, NY 10173-1922 

Attn: Todd Finger 
 Fax: 212 547 5444 

CORMORANT PRIVATE HEALTHCARE FUND I, LP 

200 Clarendon Street, 52nd Floor 
 Boston, MA 02116 

CORMORANT GLOBAL HEALTHCARE MASTER FUND, LP 

200 Clarendon Street, 52nd Floor 
 Boston, MA 02116 

CRMA SPV, L.P. 
 PO Box 309 

Ugland House 
 Grand Cayman 

KY1-1104 Cayman Islands 

AMZAK HEALTH INVESTORS, LLC 

980 North Federal Highway 
 Suite 315 Boca Raton 

FL 33432 
 Telephone No. 561
953-4164 
 Fax No. 561 338-7677 

Email: anders@majalincapital.com 
 Attn: Anders Hove 

Table of Contents

 SCHEDULE B 

KEY HOLDERS 
 Mamoun Alhamadsheh

 6361 Brook Hollow Circle 
 Stockton, CA 95219 

Isabella Graef 
 7 Durham Road 

Woodside, CA 94062 
 Jonathan C Fox and Suzanne Markel-Fox, 
 Co-Trustees of the Fox Family Trust 

Dated 17 Dec 2014 
 1788 Clay Street, Suite 809 

San Francisco, CA 94109 
 Christine Siu 

16 W. Santa Inez 
 San Mateo, CA 94402 

Uma Sinha 
 800 Junipero Serra Boulevard 

San Francisco, CA 94127EX-4.3

 Exhibit 4.3 

THIS PROMISSORY NOTE AND THE SECURITIES ISSUABLE UPON CONVERSION HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
“ACT”), OR UNDER THE SECURITIES LAWS OF APPLICABLE STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND APPLICABLE STATE
SECURITIES LAWS, PURSUANT TO REGISTRATION UNDER SUCH LAWS OR AN EXEMPTION FROM SUCH REGISTRATION REQUIREMENT. INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME. THE
ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND ALL APPLICABLE STATE SECURITIES LAWS. 

EIDOS THERAPEUTICS, INC. 

CONVERTIBLE PROMISSORY NOTE 
  

			
	 $10,000,000
	  	 February 22, 2018

 Subject to the terms and conditions of this Note, for value received, Eidos Therapeutics, Inc.,
a Delaware corporation (the “Borrower”), hereby promises to pay to BridgeBio Pharma LLC (the “Lender”), the principal sum of ten million dollars ($10,000,000) (the
“Principal Amount”), together with interest thereon accruing on and from the date hereof until the entire Balance is paid (or converted, as provided in Section 1 or Section 5 hereof), at an annual rate equal to five
percent (5.0%). Interest shall be calculated based on a 365-day year, but in no event shall the rate of interest exceed the maximum rate, if any, allowable under applicable law.
“Balance” means, at the applicable time, the sum of all then outstanding principal of this Note and all then accrued but unpaid interest under this Note. 

This convertible promissory note (the “Note”) is issued by the Borrower pursuant to that certain Note and Warrant
Purchase Agreement dated as of February 22, 2018 (the “Purchase Agreement”), entered into between the Borrower and the persons listed on Exhibit A thereto (the “Purchasers”), and is subject to,
and Borrower and Lender shall be bound by, all the terms, conditions and provisions of the Purchase Agreement. This Note, and the other notes issued pursuant to the Purchase Agreement, are sometimes hereinafter referred to as the
“Notes”. Unless otherwise converted as set forth below on the earliest of (i) a Qualified Financing (as defined herein), (ii) a Deemed Liquidation Event (as defined the Company’s Certificate of Incorporation), (iii)
a Qualified IPO (as defined herein) or (iv) February 22, 2019 (the “Maturity Date”), this Note shall become due and payable. Capitalized terms used herein but not defined herein shall have the meanings ascribed to them
in the Purchase Agreement. 

 The following is a statement of the rights of Lender and the terms and conditions
to which this Note is subject and to which the Lender, by acceptance of this Note, agrees: 
 1. Payment. 

(a) If this Note has not been previously converted (as provided in Section 5 hereof), then, subject to Section 1(b),
the principal amount of this Note and all accrued and unpaid interest under this Note shall, on the Maturity Date, be due and payable in cash upon the written demand of the Requisite Purchasers. No interest shall be payable other than as set forth
in the preceding sentence. Unless the entire Balance then outstanding under this Note is converted in accordance with Section 1(b) or Section 5 hereof, all payments on account of principal and interest shall be made in lawful money of the
United States of America at the principal office of the Lender, or such other place as the holder hereof may from time to time designate in writing to the Borrower. 

(b) Notwithstanding the foregoing, upon the affirmative written election of the Requisite Purchasers delivered to the Company
not later than five (5) days prior to the Maturity Date, the entire Balance then outstanding under all of the Notes shall be automatically converted, on the Maturity Date, into that number of shares of the Company’s Series Seed Preferred
Stock, par value $0.001 per share (the “Series Seed Preferred Stock”), as is equal to the Conversion Amount (as defined herein) divided by $1.3248 (as appropriately adjusted for any stock splits, combinations,
recapitalizations or the like affecting the Series Seed Preferred Stock after the date hereof). 
 2. No Prepayment. Except with
regard to conversion of this Note under Section 5, Borrower may not prepay this Note before it becomes due without the written consent of the Requisite Purchasers. 

3. Notes Pari Passu; Application of Payments. Each of the Notes shall rank equally without preference or priority of any kind
over one another, and all payments and recoveries payable on account of principal and interest on the Notes shall be paid and applied ratably and proportionately on the Balances of all outstanding Notes on the basis of their original principal
amount. Subject to the foregoing provisions, all payments will be applied first to accrued interest until all then outstanding accrued interest has been paid in full, and then to the repayment of principal until all principal has been paid in
full.  
 4. New Note. Upon receipt of evidence reasonably satisfactory to the Borrower of the loss, theft, destruction or
mutilation of the Note, the Borrower will issue a new Note, of like tenor and amount and dated the date to which interest has been paid, in lieu of such lost, stolen, destroyed or mutilated Note, and in such event the Lender agrees to indemnify and
hold harmless the Borrower in respect of any such lost, stolen, destroyed or mutilated Note. 
 5. Conversion of Note. 

(a) Conversion of Note upon a Qualified Financing. If the entire Balance outstanding on this Note has not been repaid
or otherwise converted before the time of the initial closing of the Borrower’s Qualified Financing (as defined below) (the “Qualified Financing Closing”), then contingent and effective upon such Qualified Financing
Closing, the entire Balance then outstanding under this Note shall be automatically converted into that number of shares of New Preferred Stock (as defined below) as is equal to the Conversion Amount (as defined below) divided by Qualified

  
 -2- 

 
Financing Conversion Price (as defined below). Borrower shall deliver to Lender notice of the Qualified Financing as soon as practicable, but in no event fewer than ten (10) days prior to
the scheduled date of the Qualified Financing Closing, notifying the Lender of the conversion to be effected, including specifying (i) the Conversion Amount (calculated as of the anticipated date of the Qualified Financing Closing), (ii) the
Qualified Financing Conversion Price and (iii) the anticipated date of the Qualified Financing Closing. 
 (i)
Qualified Financing Defined. For purposes of this Note, the term “Qualified Financing” shall mean the Borrower’s sale of shares of preferred stock (the “New Preferred Stock”) in a single
transaction or in a series of related transactions in each case occurring after the date hereof and on or before the Maturity Date, in which Borrower receives aggregate gross proceeds of at least $10,000,000 in cash (excluding the conversion of the
Notes). 
 (ii) Qualified Financing Conversion Price Defined. For purposes of this Note, the term Qualified Financing
Conversion Price shall mean an amount equal to 70% of the lowest per share purchase price at which shares of the New Preferred Stock are or have been sold in the Qualified Financing at the time of conversion of the Notes. 

(iii) Conversion Amount Defined. For purposes of this Note, the term “Conversion Amount” shall
mean the sum of all unpaid principal and accrued interest outstanding under this Note as of the date of (i) the Qualified Financing, (ii) the Qualified IPO or (iii) Deemed Liquidation Event, as applicable. 

(b) Conversion of Note upon a Qualified IPO. If the entire Balance outstanding on this Note has not been repaid or
otherwise converted before the time of the initial closing of the Borrower’s Qualified IPO (as defined below) (the “Qualified IPO Closing”), then contingent and effective upon such Qualified IPO Closing, the entire
Balance then outstanding under this Note shall be automatically converted into that number of shares of Common Stock as is equal to the Conversion Amount divided by Qualified IPO Conversion Price (as defined below). Borrower shall deliver to Lender
notice of the Qualified IPO as soon as practicable, but in no event fewer than ten (10) days prior to the scheduled date of the Qualified IPO Closing, notifying the Lender of the conversion to be effected, including specifying (i) the
Conversion Amount (calculated as of the anticipated date of the Qualified IPO Closing), (ii) the Qualified IPO Conversion Price and (iii) the anticipated date of the Qualified IPO Closing. 

(i) Qualified IPO Defined. For purposes of this Note, the term “Qualified IPO” shall mean the
Borrower’s firm commitment underwritten public offering of the Borrower’s Common Stock pursuant to a registration statement filed and effective under the Securities Act of 1933, as amended, raising at least $30,000,000 in gross proceeds to
the Borrower prior to the conversion or repayment of the Notes, occurring after the date hereof and on or before the Maturity Date. 

  
 -3- 

 (ii) Qualified IPO Conversion Price Defined. For purposes of this Note,
the term Qualified IPO Conversion Price shall mean an amount equal to price per share to the public in the Qualified IPO. 

(c) Repayment or Conversion upon Deemed Liquidation Event. At any time prior to (i) the repayment of the Notes in
accordance with the terms hereof or (ii) the conversion of the Notes in accordance with Section 1(b), 5(a) or 5(b) above, the entire Balance then outstanding under this Note shall automatically become due and payable in cash upon the
occurrence of a Deemed Liquidation Event. The Borrower shall provide to Lender ten (10) days written notice prior to the anticipated closing of any such Deemed Liquidation Event(the “Deemed Liquidation Event Closing”).
Notwithstanding the foregoing, upon the affirmative written election of the Requisite Purchasers delivered to the Company not later than five (5) days prior to the Deemed Liquidation Event Closing, the entire Balance then outstanding under all
of the Notes shall be automatically converted into that number of shares of Series Seed Preferred Stock, as is equal to the Conversion Amount divided by $1.3248 (as appropriately adjusted for any stock splits, combinations, recapitalizations or the
like affecting the Series Seed Preferred Stock after the date hereof), contingent and effective upon the Deemed Liquidation Event Closing. 

(d) Covenants regarding Conversion Stock. Prior to the conversion of this Note into New Preferred Stock or Series Seed
Preferred Stock pursuant to the terms hereof, (i) Borrower shall use its reasonable best efforts (without the payment of additional monies) to authorize and reserve promptly a sufficient number of shares of New Preferred Stock or Series Seed
Preferred Stock (and any shares of Common Stock issuable upon the conversion thereof), to permit such conversion, including obtaining the requisite corporate approvals and stockholder consents and the filing of an amendment to the Company’s
certificate incorporation in effect at such time with the Secretary of the State of Delaware, and (ii) Lender shall cooperate with Borrower in connection therewith, including by executing and delivering such consents and other agreements or
documents in Lender’s capacity as a stockholder of Borrower as may be necessary for Borrower to effect such actions. 

(e) Termination of Rights. Except for the rights to obtain certificates representing New Preferred Stock or Series Seed
Preferred Stock (and cash in lieu of fractional shares) set forth in Section 5(f) below, all rights with respect to this Note shall terminate upon the effective conversion or repayment of the entire Balance of the Note, whether or not this Note
has been surrendered to Borrower for cancellation. 
 (f) Delivery of Stock Certificates; No Fractional Shares.
Subject to Section 5(d) above, as promptly as practicable after any conversion of this Note, Borrower at its expense will issue and deliver to Lender a certificate or certificates evidencing the number of full equity securities as are issuable
to Lender in connection with a conversion under this Section 5. No fractional shares of any of Borrower’s equity securities will be issued in connection with any conversion hereunder. In lieu of fractional shares that would otherwise be
issuable, Borrower shall pay cash equal to the product of such fraction multiplied by the Qualified Financing Conversion Price or Qualified IPO Conversion Price, as applicable, or the price per share of such other securities issuable to Lender upon
such conversion, as appropriate. 

  
 -4- 

 6. Events of Default. Each of the following shall constitute an “Event of
Default” hereunder: 
 (a) The Borrower shall fail to pay any principal or interest payable hereunder on
the applicable due date and such failure continues for ten (10) days; 
 (b) The Borrower shall (i) voluntarily
terminate operations or apply for or consent to the appointment of, or the taking of possession by, a receiver, custodian, trustee or liquidator of the Borrower or of all or a substantial part of the assets of the Borrower, (ii) admit in
writing its inability to pay debts as the debts become due, (iii) make a general assignment for the benefit of its creditors, (iv) commence a voluntary case under the Federal Bankruptcy Code (as now or hereafter in effect), (v) file a
petition seeking to take advantage of any other law relating to bankruptcy, insolvency, reorganization, winding-up, or composition or adjustment of debts, (vi) fail to controvert in a timely and
appropriate manner, or acquiesce in writing to, any petition filed against it in an involuntary case under the Federal Bankruptcy Code or applicable state bankruptcy laws or (vii) take any corporate action for the purpose of effecting any of
the foregoing; 
 (c) Without the Borrower’s application, approval or consent, a proceeding shall be commenced, in
any court of competent jurisdiction, seeking in respect of the Borrower: the liquidation, reorganization, dissolution, winding-up, or composition or readjustment of debt, the appointment of a trustee,
receiver, liquidator or the like relief in respect of the Borrower or all or any substantial part of the assets of the Borrower, or other like relief in respect of the Borrower under any law relating to bankruptcy, insolvency, reorganization, winding-up, or composition or adjustment of debts; and, if the proceeding is being contested in good faith by the Borrower, the same shall continue undismissed, or unstayed and in effect for any period of 90
consecutive days, or an order for relief against the Borrower shall be entered in any case under the Federal Bankruptcy Code or applicable bankruptcy laws; or 

(d) The Borrower’s representations and warranties contained in the Purchase Agreement shall prove to have not been
true in any material respect when made. 
 If any Event of Default shall occur, then, at any time thereafter while such Event of Default is
continuing, the Requisite Purchasers, by written notice to the Borrower (the “Default Notice”) may declare the entire Balance under all of the Notes then outstanding, to be due and payable immediately; provided, however, that
in the case of an Event of Default under Subsections 6(b) or 6(c) above, the Balance under this Note shall automatically become immediately due and payable to Lender without a written election of the Requisite Purchasers. 

7. Governing Law. This Note shall be governed by and construed in accordance with the Delaware General Corporation Law as to matters
within the scope thereof, and as to all other matters shall be governed by, and construed in accordance with, the internal laws of the State of California, without reference to principles of conflict of laws or choice of laws. 

  
 -5- 

 8. Amendment. This Note may not be amended or modified, or any provision hereof waived,
nor may any rights and remedies available upon the Maturity Date or an Event of Default be exercised, except by a written instrument signed in accordance with the amendment, waiver and exercise of remedies provisions set forth in Section 6.02
of the Purchase Agreement. 
 9. Waiver. Borrower hereby waives presentment, protest, demand for payment, notice of dishonor, and any
and all other notices or demands in connection with the delivery, acceptance, performance, default, or enforcement of this Note. 
 10.
Severability. The invalidity or unenforceability of any provision hereof shall in no way affect the validity or enforceability of any other provision. 

11. Addresses for Notices, etc. Any notice required or permitted hereunder shall be given in writing and shall be conclusively deemed
effectively given (a) upon personal delivery or delivery by courier, (b) when sent, if sent by electronic mail or facsimile during normal business hours of the recipient, and if not sent during normal business hours, then on the next
business day after transmission if sent by confirmed electronic mail or facsimile transmission, (c) for domestic United States deliveries, four (4) business days after deposit in the United States mail, by registered or certified mail,
postage prepaid, or (d) for international deliveries, four (4) business days after deposit with an internationally recognized overnight delivery service, specifying two- (2-) day delivery, postage prepaid, addressed (i) if to Borrower, at the principal offices of Borrower and (ii) if to Lender, at Lender’s address as set forth on Exhibit A to the Purchase Agreement,
or at such other address as Borrower or Lender may designate by advance written notice to the other party hereto. For purposes of this Section 11, a “business day” means a weekday on which banks are open for general
banking business in San Francisco, California. 
 12. Headings; Interpretation. In this Note, (i) the meaning of defined terms
shall be equally applicable to both the singular and plural forms of the terms defined; (ii) the captions and headings are used only for convenience and are not to be considered in construing or interpreting this Note and (iii) the words
“including,” “includes” and “include” shall be deemed to be followed by the words “without limitation”. All references in this Note to sections, paragraphs, exhibits and schedules shall, unless otherwise
provided, refer to sections and paragraphs hereof and exhibits and schedules attached hereto, all of which exhibits and schedules are incorporated herein by this reference. 

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] 

  
 -6- 

 IN WITNESS WHEREOF, the undersigned has caused this instrument to be executed by
its duly authorized officers as of the date first above written. 
  

							
	BORROWER:	 		 	EIDOS THERAPEUTICS, INC.
				
		 		 	By	 	/s/ Christine Siu
		 		 	Name:	 	Christine Siu
		 		 	Title:	 	Chief Financial Officer

 Acknowledged and agreed by Lender: 
  

			
	BRIDGEBIO PHARMA LLC
		
	By:	 	/s/ Neil Kumar
	Name:	 	Neil Kumar
	Title:	 	Chief Executive Officer

 SIGNATURE PAGE TO CONVERTIBLE PROMISSORY NOTE

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