Document:

EX-4.2

 Exhibit 4.2 

AMENDED AND RESTATED 

INVESTORS’ RIGHTS AGREEMENT 
  

 TABLE OF CONTENTS 

 

									
	 	 	 	 	 	  	Page	 
	 1.
	 	 Definitions
	  	 	1	 
			
	 2.
	 	 Registration Rights
	  	 	5	 
		 	 2.1
	 	 Demand Registration
	  	 	5	 
		 	 2.2
	 	 Company Registration
	  	 	6	 
		 	 2.3
	 	 Underwriting Requirements
	  	 	7	 
		 	 2.4
	 	 Obligations of the Company
	  	 	8	 
		 	 2.5
	 	 Furnish Information
	  	 	10	 
		 	 2.6
	 	 Expenses of Registration
	  	 	10	 
		 	 2.7
	 	 Delay of Registration
	  	 	10	 
		 	 2.8
	 	 Indemnification
	  	 	10	 
		 	 2.9
	 	 Reports Under Exchange Act
	  	 	13	 
		 	 2.10
	 	 Limitations on Subsequent Registration Rights
	  	 	13	 
		 	 2.11
	 	 “Market Stand-off” Agreement
	  	 	13	 
		 	 2.12
	 	 Restrictions on Transfer
	  	 	14	 
		 	 2.13
	 	 Termination of Registration Rights
	  	 	16	 
			
	 3.
	 	 Information and Observer Rights
	  	 	16	 
		 	 3.1
	 	 Delivery of Financial Statements
	  	 	16	 
		 	 3.2
	 	 Inspection
	  	 	17	 
		 	 3.3
	 	 Observer Rights
	  	 	17	 
		 	 3.4
	 	 Termination of Information and Observer Rights
	  	 	18	 
		 	 3.4
	 	 Confidentiality
	  	 	18	 
			
	 4.
	 	 Rights to Future Stock Issuances
	  	 	18	 
		 	 4.1
	 	 Right of First Offer
	  	 	18	 
		 	 4.2
	 	 Termination
	  	 	20	 
			
	 5.
	 	 Additional Covenants
	  	 	20	 
		 	 5.1
	 	 Insurance
	  	 	20	 
		 	 5.2
	 	 Employee Agreements
	  	 	20	 
		 	 5.3
	 	 Employee Stock
	  	 	20	 
		 	 5.4
	 	 Matters Requiring Investor Director Approval
	  	 	21	 
		 	 5.5
	 	 Board Matters
	  	 	21	 
		 	 5.6
	 	 Successor Indemnification
	  	 	21	 
		 	 5.7
	 	 Indemnification Matters
	  	 	22	 
		 	 5.8
	 	 Right to Conduct Activities
	  	 	22	 
		 	 5.9
	 	 FCPA
	  	 	22	 
		 	 5.10
	 	 Termination of Covenants
	  	 	23	 
			
	 6.
	 	 Miscellaneous
	  	 	23	 

  
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		 	 6.1
	 	 Successors and Assigns
	  	 	23	 
		 	 6.2
	 	 Governing Law
	  	 	24	 
		 	 6.3
	 	 Counterparts
	  	 	24	 
		 	 6.4
	 	 Titles and Subtitles
	  	 	24	 
		 	 6.5
	 	 Notices
	  	 	24	 
		 	 6.6
	 	 Amendments and Waivers
	  	 	24	 
		 	 6.7
	 	 Severability
	  	 	25	 
		 	 6.8
	 	 Aggregation of Stock
	  	 	25	 
		 	 6.9
	 	 Additional Investors
	  	 	25	 
		 	 6.10
	 	 Entire Agreement
	  	 	25	 
		 	 6.11
	 	 Dispute Resolution
	  	 	25	 
		 	 6.12
	 	 Delays or Omissions
	  	 	26	 

  

			
	Schedule A    -	  	Schedule of Investors

  

  
 ii 

 AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT 

THIS AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT (this “Agreement”), is made as of the 29th day of November, 2017, by and among resTORbio, 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 any Additional Purchaser (as defined in the Purchase Agreement) that becomes a party to this Agreement in accordance with Section 6.9 hereof. 

RECITALS 

WHEREAS, certain of the Investors (the “Existing Investors”) hold shares of the Company’s Series A 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 March 23, 2017 between
the Company and such Investors (the “Prior Agreement”); and 
 WHEREAS, the Existing Investors are holders of 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 the Investors under the Prior Agreement; and 
 WHEREAS, certain of the Investors are parties to that certain Series B Preferred
Stock Purchase Agreement dated as of October 27, 2017 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 a majority of the Registrable Securities, and the Company; 

WHEREAS, in order to induce the Investors party thereto to invest funds in the Company pursuant to the Purchase Agreement, the
Investors and the Company hereby agree that this Agreement shall govern the rights of the Investors to cause the Company to register shares of Common Stock issuable to the Investors, to receive certain information from the Company, and to
participate in future equity offerings by the Company, and shall govern certain other matters as set forth in this Agreement; 
 NOW,
THEREFORE, the Existing Investors hereby agree that the Prior Agreement shall be amended and restated and replaced in its entirety as set forth herein, 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 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. 

 1.2 “Common Stock” means shares of the Company’s common stock, par value
$0.0001 per share. 
 1.3 “Competitor” means a Person engaged, directly or indirectly (including through any
partnership, limited liability company, corporation, joint venture or similar arrangement (whether now existing or formed hereafter)), in the discovery and/or development of chemical entities with a primary mechanism of action modulating TORC1,
S6K, 4EBP1 or Ulk1, but shall not include any financial investment firm or collective investment vehicle that, together with its Affiliates, holds less than twenty percent (20)% of the outstanding equity of any Competitor and does not, nor do any of
its Affiliates, have a right to designate any members of the Board of Directors of any Competitor; provided, that, in no event shall PureTech, Novartis or OrbiMed be considered a Competitor. 

1.4 “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. 

1.5 “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. 
 1.6 “Exchange Act” means the Securities
Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 
 1.7 “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. 

  
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 1.8 “FOIA Party” means a Person that, in the reasonable determination of the
Board of Directors, may be subject to, and thereby required to disclose non-public information furnished by or relating to the Company under, the Freedom of Information Act, 5 U.S.C. 552
(“FOIA”), any state public records access law, any state or other jurisdiction’s laws similar in intent or effect to FOIA, or any other similar statutory or regulatory requirement. 

1.9 “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. 
 1.10 “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. 
 1.11 “GAAP” means generally accepted
accounting principles in the United States. 
 1.12 “Holder” means any holder of Registrable Securities who is a party to
this Agreement. 
 1.13 “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. 

1.14 “Initiating Holders” means, collectively, Holders who properly initiate a registration request under this Agreement.

 1.15 “IPO” means the Company’s first underwritten public offering of its Common Stock under the Securities Act.

 1.16 “Key Employee” means any executive-level employee (including, division director and vice president-level positions)
as well as any employee who, either alone or in concert with others, develops, invents, programs, or designs any Company Intellectual Property (as defined in the Purchase Agreement). 

1.17 “Major Investor” means any Investor that, individually or together with such Investor’s Affiliates, holds at least
1,000,000 shares of Registrable Securities (as adjusted for any stock split, stock dividend, combination, or other recapitalization or reclassification effected after the date hereof). 

1.18 “New Securities” means, collectively, equity securities of the Company, whether or not currently authorized, as well as
rights, options, or warrants to purchase such equity securities, or securities of any type whatsoever that are, or may become, convertible or exchangeable into or exercisable for such equity securities. 

  
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 1.19 “Novartis” Novartis Institutes for BioMedical Research, Inc. and its
Affiliates. 
 1.20 “Person” means any individual, corporation, partnership, trust, limited liability company, association
or other entity. 
 1.21 “Preferred Stock” means, collectively, shares of the Company’s Series A Preferred Stock and
Series B Preferred Stock. 
 1.22 “Registrable Securities” means (i) the Common Stock issuable or issued upon
conversion of the Preferred Stock held from time to time by the Investors and their permitted assigns; (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; and (iii) any Common Stock issued as (or issuable upon the conversion or exercise of any warrant, right, or other security
that is issued as) a dividend or other distribution with respect to, or in exchange for or in replacement of, the shares referenced in clauses (i) and (ii) above; 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 6.1, and excluding for purposes of Section 2 any shares for which registration rights have
terminated pursuant to Subsection 2.13 of this Agreement. 
 1.23 “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. 
 1.24 “Restricted Securities” means the
securities of the Company required to be notated with the legend set forth in Subsection 2.12(b) hereof. 
 1.25
“SEC” means the Securities and Exchange Commission. 
 1.26 “SEC Rule 144” means Rule 144 promulgated by
the SEC under the Securities Act. 
 1.27 “SEC Rule 145” means Rule 145 promulgated by the SEC under the Securities Act.

 1.28 “Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated
thereunder. 
 1.29 “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. 

  
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 1.30 “Series A Preferred Stock” means shares of the
Company’s Series A Preferred Stock, par value $0.0001 per share. 
 1.31 “Series B Preferred Stock” means shares of
the Company’s Series B Preferred Stock, par value $0.0001 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) four (4) 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 at least twenty percent (20%) of the Registrable Securities then
outstanding that the Company file a Form S-1 registration statement with respect to at least forty percent (40%) of the Registrable Securities then outstanding (or a lesser percent if the anticipated
aggregate offering price, net of Selling Expenses, would exceed $15 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 ten percent 10%) 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 $10 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. 

(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 

  
 5 

 
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, and any time periods with respect to filing or effectiveness thereof shall be
tolled correspondingly, for a period of not more than one hundred twenty (120) 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; and provided further that the Company shall not register any securities for its own account or that of any other stockholder during such one hundred twenty (120) day period other than an Excluded
Registration. 
 (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 sixty (60) 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 ninety (90) 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; 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 Common Stock 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. To facilitate the allocation of shares in accordance with the above provisions, the Company
or the underwriters may round the number of shares allocated to any Holder to the nearest one hundred (100) shares. 
 (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 

  
 7 

 
such selling Holders. To facilitate the allocation of shares in accordance with the above provisions, the Company or the underwriters may round the number of shares allocated to any Holder to the
nearest one hundred (100) shares. 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 number of Registrable Securities included in the offering be reduced below twenty percent (20%) of the total number of securities included in such offering, unless such offering is the
IPO, in which case the selling Holders may be excluded further if the underwriters make the determination described above and no other stockholder’s securities are 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 (i) 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, and (ii) in the case of any registration of Registrable Securities on Form S-3 that are intended to be offered on a continuous or delayed basis, subject to
compliance with applicable SEC rules, such one hundred twenty (120) day period shall be extended for up to ninety (90) days, if necessary, to keep the registration statement effective until all such Registrable Securities are sold; 

(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; 

  
 8 

 (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; 

(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 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.

  
 9 

 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 of one counsel for the selling Holders (“Selling Holder Counsel”), 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 

  
 10 

 
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 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. The failure to give notice to the
indemnifying party within a reasonable time of the commencement of any such action shall relieve such indemnifying party of any liability to the indemnified party under this 

  
 11 

 
Subsection 2.8, to the extent that such failure materially prejudices the indemnifying party’s ability to defend such action. The failure to give notice to the indemnifying party will
not relieve it of any liability that it may have to any indemnified party otherwise than under this Subsection 2.8. 
 (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 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) Notwithstanding the foregoing, to the extent that the provisions on indemnification and contribution contained in the underwriting
agreement entered into in connection with the underwritten public offering are in conflict with the foregoing provisions, the provisions in the underwriting agreement shall control. 

(f) 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. 

  
 12 

 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). 

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 Holders holding at least (i) a majority of the shares of Common Stock issued or issuable upon conversion of the Series A Preferred Stock, voting together as a single class and (ii) a majority of the shares of Common
Stock issued or issuable upon conversion of the Series B Preferred Stock, voting together as a single class (the foregoing clauses (i) and (ii) together, the “Requisite Holders”), enter into any agreement with any holder or
prospective holder of any securities of the Company that would provide to such holder the right to include securities in any registration on other than either a pro rata basis with respect to the Registrable Securities or on a subordinate basis
after all Holders have had the opportunity to include in the registration and offering all shares of Registrable Securities that they wish to so include. 

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 for its own behalf 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) 

  
 13 

 
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 and directors and holders of more than one percent (1%) of the Company’s
outstanding Common Stock (after giving effect to conversion into Common Stock of all outstanding Preferred Stock) enter into similar agreements. 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. Any discretionary waiver or
termination of the restrictions of any or all of such agreements by the Company or the underwriters shall apply pro rata to all Holders subject to such agreements, based on the number of shares subject to such agreements. 

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: 

  
 14 

 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, 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 or transfers 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. 

  
 15 

 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 fifth anniversary of the IPO. 

3. Information and Observer Rights. 

3.1 Delivery of Financial Statements. The Company shall deliver to each Major Investor, provided that the Board of Directors has
not reasonably determined that such Major Investor is a Competitor of the Company: 
 (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; provided that, in the event that the Company undertakes an audit of such financial statements, all financial statements delivered to each Major Investor pursuant to this Section 3.1(a) for
the fiscal year of such audit and thereafter shall be audited and certified by independent public accountants of nationally recognized standing selected by the Company; 

(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 and a statement of stockholders’ equity 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); 
 (c) 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, a statement showing the number of shares of each class and series of capital stock and securities convertible into or exercisable for shares of capital stock outstanding at the
end of the period, the Common Stock issuable upon conversion or exercise of any outstanding securities convertible or exercisable for Common Stock and the exchange ratio or exercise price applicable thereto, and the number of shares of issued stock
options and stock options not yet issued but reserved for issuance, if any, all in sufficient detail as to permit the Major Investors to calculate their respective percentage equity ownership in the Company, and certified by the chief financial
officer or chief executive officer of the Company as being true, complete, and correct; 

  
 16 

 (d) as soon as practicable, but in any event thirty (30) days before the end of each fiscal
year, a budget and business plan for the next fiscal year (collectively the “Budget”), 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 
 (e) 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); 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 (provided that the Board of Directors has not reasonably determined that such Major Investor is a Competitor of the Company), 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) or the disclosure of which would adversely affect the attorney-client privilege between the Company and its counsel. 

3.3 Observer Rights. The Company shall invite (i) a representative of Novartis, for as long as Novartis is a Major Investor, and
(ii) Joan Mannick, for as long as Joan Mannick is an officer of the Company, to attend all meetings of its Board of Directors in a nonvoting observer capacity and, in this respect, shall give such representatives 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 such directors; provided, however, that such 

  
 17 

 
representatives 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 representatives from any meeting or portion thereof if access to such information or attendance at such meeting would (after consultation with qualified outside counsel) reasonably be expected to
adversely affect the attorney-client privilege between the Company and its counsel. 
 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, (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 3.4 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, 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 3.4, provided
that the Board of Directors has not reasonably determined that such prospective purchaser is a Competitor of the Company; (iii) to any existing or prospective Affiliate, partner, member, stockholder, 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. 

4. Rights to Future Stock Issuances. 

4.1 Right of First Offer. Subject to the terms and conditions of this Subsection 4.1 and applicable securities laws, if the
Company proposes to offer or sell any New Securities, the Company shall first offer such New Securities to each Investor. An Investor shall be entitled to apportion the right of first offer hereby granted to it, in such proportions as it deems
appropriate, among (i) itself, (ii) its Affiliates and (iii) its beneficial interest holders, such as limited partners, members or any other Person having “beneficial ownership,” as such term is defined in Rule 13d-3 promulgated under the Exchange Act, of such Investor (“Investor Beneficial Owners”); provided that each such Affiliate or Investor Beneficial Owner (x) is not a

  
 18 

 
Competitor or FOIA Party, unless such party’s purchase of New Securities is otherwise consented to by the Board of Directors, (y) agrees to enter into this Agreement and each of the
Voting Agreement and Right of First Refusal and Co-Sale Agreement of even date herewith among the Company, the Investors and the other parties named therein, as an “Investor” under each such
agreement (provided that any Competitor or FOIA Party shall not be entitled to any rights as an Investor under Subsections 3.1, 3.2 and 4.1 hereof), and (z) agrees to purchase at least such number of New Securities
as are allocable hereunder to the Investor holding the fewest number of shares of Preferred Stock and any other Derivative Securities. 

(a) The Company shall give notice (the “Offer Notice”) to each Investor, stating (i) its bona fide intention to offer
such New Securities, (ii) the number of such New Securities to be offered, and (iii) the price and terms, if any, upon which it proposes to offer such New Securities. 

(b) By notification to the Company within twenty (20) days after the Offer Notice is given, each Investor may elect to purchase or
otherwise acquire, at the price and on the terms specified in the Offer Notice, up to that portion of such New Securities which equals the proportion that the Common Stock then held by such Investor (including all shares of Common Stock then
issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of the Preferred Stock and any other Derivative Securities then held by such Investor) bears to the total Common Stock of the Company then outstanding (assuming full
conversion and/or exercise, as applicable, of all Preferred Stock and other Derivative Securities). At the expiration of such twenty (20) day period, the Company shall promptly notify each Investor that elects to purchase or acquire all the
shares available to it (each, a “Fully Exercising Investor”) of any other Investor’s failure to do likewise. During the ten (10) day period commencing after the Company has given such notice, each Fully Exercising Investor
may, by giving notice to the Company, elect to purchase or acquire, in addition to the number of shares specified above, up to that portion of the New Securities for which Investors were entitled to subscribe but that were not subscribed for by the
Investors which is equal to the proportion that the Common Stock issued and held, or issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of Preferred Stock and any other Derivative Securities then held, by such Fully
Exercising Investor bears to the Common Stock issued and held, or issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of the Preferred Stock and any other Derivative Securities then held, by all Fully Exercising
Investors who wish to purchase such unsubscribed shares. The closing of any sale pursuant to this Subsection 4.1(b) shall occur within the later of ninety (90) days of the date that the Offer Notice is given and the date of initial sale
of New Securities pursuant to Subsection 4.1(c). 
 (c) If all New Securities referred to in the Offer Notice are not elected to be
purchased or acquired as provided in Subsection 4.1(b), the Company may, during the ninety (90) day period following the expiration of the periods provided in Subsection 4.1(b), offer and sell the remaining unsubscribed portion of
such New Securities to any Person or Persons at a price not less than, and upon terms no more favorable to the offeree than, those specified in the Offer Notice. If the Company does not enter into an agreement for the sale of the New Securities
within such period, or if such agreement is not consummated within thirty (30) days of the execution thereof, the right provided hereunder shall be deemed to be revived and such New Securities shall not be offered unless first reoffered to the
Investors in accordance with this Subsection 4.1. 

  
 19 

 (d) The right of first offer in this Subsection 4.1 shall not be applicable to
(i) Exempted Securities (as defined in the Company’s Certificate of Incorporation); (ii) shares of Common Stock issued in the IPO; and (iii) the issuance of shares of Series B Preferred Stock pursuant to the Purchase Agreement. 

4.2 Termination. The covenants set forth in Subsection 4.1 shall terminate and be of no further force or effect
(i) immediately before the consummation of the IPO, or (ii) upon a Deemed Liquidation Event, as such term is defined in the Company’s Certificate of Incorporation. 

5. Additional Covenants. 

5.1 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 and term “key-person” insurance on Chen Schor and Joan Mannick, 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. The key-person policy shall name the Company as loss payee, and neither policy shall be cancelable by the Company without prior approval by the Board of Directors. 

5.2 Employee Agreements. The Company will cause (i) 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; and (ii) each Key Employee now or
hereafter employed by it or by any subsidiary to enter into a one (1) year noncompetition and nonsolicitation agreement, substantially in the form approved by the Board of Directors. In addition, the Company shall not amend, modify, terminate,
waive, or otherwise alter, in whole or in part, any of the above-referenced agreements or any restricted stock agreement between the Company and any employee, without the consent of the Board of Directors. 

5.3 Employee Stock. Unless otherwise approved by the Board of Directors, 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. 

  
 20 

 5.4 Matters Requiring Investor Director Approval. The Company hereby covenants and agrees
with each of the Investors that it shall not, without approval of the Board of Directors: 
 (a) make, or permit any subsidiary to make, any
loan or advance to, or own any stock or other securities of, any subsidiary or other corporation, partnership, or other entity unless it is wholly owned by the Company; 

(b) make, or permit any subsidiary to make, any loan or advance to any Person, including, without limitation, any employee or director of the
Company or any subsidiary, except advances and similar expenditures in the ordinary course of business or under the terms of an employee stock or option plan approved by the Board of Directors; 

(c) guarantee, directly or indirectly, or permit any subsidiary to guarantee, directly or indirectly, any indebtedness except for trade
accounts of the Company or any subsidiary arising in the ordinary course of business; 
 (d) make any investment inconsistent with any
investment policy approved by the Board of Directors; 
 (e) incur any indebtedness that is not already included in a budget approved by the
Board of Directors, other than trade credit incurred in the ordinary course of business; 
 (f) hire, terminate, or change the compensation
of the executive officers, including approving any option grants or stock awards to executive officers; or 
 (g) change the principal
business of the Company, enter new lines of business, or exit the current line of business. 
 5.5 Board Matters. Unless otherwise
determined by the vote of a majority of the directors then in office, the Board of Directors shall meet at least quarterly in accordance with an agreed-upon schedule. The Company shall reimburse the nonemployee directors for all reasonable out-of-pocket travel expenses incurred (consistent with the Company’s travel policy) in connection with attending meetings of the Board of Directors. 

5.6 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. 

  
 21 

 5.7 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 an “Investor 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 “Investor Indemnitors”). The Company hereby agrees (a) that it is the indemnitor of first resort (i.e., its obligations to any such Investor Director are primary
and any obligation of the Investor Indemnitors to advance expenses or to provide indemnification for the same expenses or liabilities incurred by such Investor Director are secondary), (b) that it shall be required to advance the full amount of
expenses incurred by such Investor 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 Investor 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 Investor Director), without regard to any rights such Investor Director may have against the Investor Indemnitors,
and, (c) that it irrevocably waives, relinquishes and releases the Investor Indemnitors from any and all claims against the Investor 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 Investor Indemnitors on behalf of any such Investor Director with respect to any claim for which such Investor Director has sought indemnification from the Company shall affect the
foregoing and the Investor 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 Investor Director against the Company. 

5.8 Right to Conduct Activities. The Company hereby agrees and acknowledges that each of PureTech Health LLC
(together with its Affiliates), OrbiMed (together with its Affiliates) and Novartis (together with its Affiliates) is a healthcare business, and as such invests 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, none of PureTech Health LLC, OrbiMed or Novartis shall be liable to the
Company for any claim arising out of, or based upon, (i) the investment by PureTech Health LLC, OrbiMed and/or Novartis (or any of their respective Affiliates) in any entity competitive with the Company, or (ii) actions taken by any
partner, officer or other representative of PureTech Health LLC, OrbiMed and/or Novartis (or any of their respective 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. 

5.9 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 

  
 22 

 
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. 
 5.10 Termination of Covenants. The covenants set forth
in this Section 5, except for Subsections 5.6 and 5.7, shall terminate and be of no further force or effect (i) immediately before the consummation of the IPO, (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. 
 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 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. 

  
 23 

 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 Stockholders, a copy shall also be given to Sidley Austin LP, 787 7th Avenue, New
York, NY 10019, Attn: Geoffrey W. Levin. 
 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 Requisite Holders; 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); 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, (i) 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 (provided that the rights granted to Major Investors in Section 4 may not be waived with respect to a particular transaction unless all Major Investors are 

  
 24 

 
provided with the opportunity to purchase Shares on similar terms and in proportionally similar amounts as the other Major Investors who are participating in such offering), (ii) Subsection
1.17 (solely as it relates to Novartis and its Affiliates) and Subsection 3.3 may not be amended or waived without the prior written consent of Novartis, and (iii) an amendment to the definition of Major Investor in
Section 1.17 that would cause a Major Investor to no longer qualify as a Major Investor shall require the consent of such Major Investor. 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. 

6.11 Dispute Resolution. The parties (a) hereby irrevocably and unconditionally submit to the jurisdiction of the state courts of
Delaware and to the jurisdiction of the United States District Court for the District of Delaware for the purpose of any suit, action or other proceeding arising out of or based upon this Agreement, (b) agree not to commence any suit, action or
other proceeding arising out of or based upon this Agreement except in the state courts of Delaware or the United States District Court for the District of Delaware, and (c) 

  
 25 

 
hereby waive, and agree not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the
above-named courts, that its property is exempt or immune from attachment or execution, that the suit, action or proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or
the subject matter hereof may not be enforced in or by such court. 
 WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF
ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT, THE OTHER TRANSACTION DOCUMENTS, THE SECURITIES OR THE SUBJECT MATTER HEREOF OR THEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE
ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT MATTER OF THIS TRANSACTION, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING
NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS BEEN FULLY DISCUSSED BY EACH OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER
WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH PARTY KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL. 

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. 
 [Remainder of Page Intentionally Left Blank] 

  
 26 

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

  

			
	RESTORBIO, INC.
		
	By:	 	 /s/ Chen Schor

	Name: Chen Schor
	Title: Chief Executive Officer

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	INVESTORS:
	
	PURETECH HEALTH LLC 
		
	By:	 	 /s/ Stephen Muniz

	Name: Stephen Muniz
	Title: Chief Operating Officer

  

			
	NOVARTIS INSTITUTES FOR BIOMEDICAL RESEARCH, INC.
		
	By:	 	  

	Name:
	Title:

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	ORBIMED PRIVATE INVESTMENTS VI, LP
	BY: 	 	ORBIMED CAPITAL GP VI LLC,
	ITS: GENERAL PARTNER
	BY: ORBIMED ADVISORS LLC 
	ITS: MANAGING MEMBER
		
	By:	 	 /s/ Jonathan Silverstein

	Name: Jonathan Silverstein
	Title: Member

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	 Fidelity Contrafund: Fidelity Advisor

	 New Insights
Fund

 
			
		
	By:	 	 /s/ Colm Hogan

	 Name: Colm Hogan

	 Title: Authorized Signatory

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	Rock Springs Capital Master Fund LP
	By: Rock Springs General Partner LLC
		
	By:	 	 /s/ Kris N. Jenner

	Name:Kris N. Jenner
	Title: Managing Member

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	Quan Venture Fund I, L.P.
	
	By: Quan Venture Partners I, L.L.C. 
	Its: General Partner
		
	By:	 	 /s/ Marietta Wu

	Name: Marietta Wu
	Title: Managing Director

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	LEERINK HOLDINGS LLC
		
	By:	 	 /s/ Timothy A.G. Gerhold

		 	Name: Timothy A.G. Gerhold
		 	Title: Genreal Counsel
	
	LEERINK SWANN CO-INVESTMENT FUND, LLC
		
	By:	 	 /s/ Jeffrey A. Leerink

		 	Name: Jeffrey A. Leerink
		 	Title: Manager

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 
			
	NESTBIO WO VI HOLDING LP
	
	BY: ADENA PARTNERS GP I, LLC
	ITS GENERAL PARTNER 
		
	By:	 	 /s/ Cheryl Hao Cui

	Name: Cheryl Hao Cui
	Title: Member

 [Signature Page to Amended and Restated Investors’ Rights Agreement] 

 SCHEDULE A 

Investors 
 PureTech Health LLC 

501 Boylston Street, Suite 6102 
 Boston, Massachusetts 02116 

Novartis Institutes for BioMedical Research, Inc. 
 250
Massachusetts Avenue 
 Cambridge, MA 02139 
 Attn: General
Counsel 
 OrbiMed Private Investments VI, LP 
 601 Lexington
Avenue 
 New York, NY 10022 
  

	
	 Fidelity Contrafund: Fidelity Advisor New Insights Fund

Mag & Co.

c/o Brown Brothers Harriman & Co.

Attn: Corporate Actions /Vault

140 Broadway

New York, NY 10005

BBH.Fidelity.CA.Notifications@BBH.com

	
	 Quan Venture Fund I, L.P.
 Ugland House, PO
Box 309
 Grand Cayman, Cayman Islands KY1-1104

	
	 Leerink Holdings LLC

c/o Leerink Partners LLC

One Federal Street, 37th Floor

Boston, MA 02110

Attention: General Counsel

	
	 Leerink Swann Co-Investment Fund, LLC

c/o Leerink Partners LLC

One Federal Street, 37th Floor

Boston, MA 02110

Attention: General Counsel

	
	 Rock Springs Capital Master Fund LP

650 South Exeter Street #1070

Baltimore, Maryland 21202

	
	 Nestbio WO VI Holding LP

43 Charles St., Unit 2

Boston, MA 02114

Attention: Cheryl CuiEX-10.1

 Exhibit 10.1 

RESTORBIO, INC. 
 2017 STOCK
INCENTIVE PLAN 
 1. Purpose 
 The
purpose of this 2017 Stock Incentive Plan (the “Plan”) of resTORbio, Inc., a Delaware corporation (the “Company”), is to advance the interests of the Company’s stockholders by enhancing the
Company’s ability to attract, retain and motivate persons who are expected to make important contributions to the Company and by providing such persons with equity ownership opportunities and performance-based incentives that are intended to
better align the interests of such persons with those of the Company’s stockholders. Except where the context otherwise requires, the term “Company” shall include any of the Company’s present or future parent or subsidiary
corporations as defined in Sections 424(e) or (f) of the Internal Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”) and any other business venture (including, without limitation,
joint venture or limited liability company) in which the Company has a controlling interest, as determined by the Board of Directors of the Company (the “Board”). 

2. Eligibility 
 All of the Company’s
employees, officers, directors, consultants and advisors are eligible to be granted options, restricted stock, restricted stock units and other stock-based awards (each, an “Award”) under the Plan. Each person who receives an Award
under the Plan is deemed a “Participant”. 
 3. Administration and Delegation 

(a) Administration by Board of Directors. The Plan will be administered by the Board. The Board shall have authority to grant Awards and
to adopt, amend and repeal such administrative rules, guidelines and practices relating to the Plan as it shall deem advisable. The Board may construe and interpret the terms of the Plan and any Award agreements entered into under the Plan. The
Board may correct any defect, supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem expedient to carry the Plan into effect and it shall be the sole and final judge of such
expediency. All decisions by the Board shall be made in the Board’s sole discretion and shall be final and binding on all persons having or claiming any interest in the Plan or in any Award. No director or person acting pursuant to the
authority delegated by the Board shall be liable for any action or determination relating to or under the Plan made in good faith. 
 (b)
Appointment of Committees. To the extent permitted by applicable law, the Board may delegate any or all of its powers under the Plan to one or more committees or subcommittees of the Board (a “Committee”). All references in
the Plan to the “Board” shall mean the Board or a Committee of the Board or the officers referred to in Section 3(c) to the extent that the Board’s powers or authority under the Plan have been delegated to such Committee or
officers. 

 (c) Delegation to Officers. To the extent permitted by applicable law, the Board may
delegate to one or more officers of the Company the power to grant Awards (subject to any limitations under the Plan) to employees or officers of the Company or any of its present or future subsidiary corporations and to exercise such other powers
under the Plan as the Board may determine, provided that the Board shall fix the terms of the Awards to be granted by such officers (including the exercise price of such Awards, which may include a formula by which the exercise price will be
determined) and the maximum number of shares subject to Awards that the officers may grant; provided further, however, that no officer shall be authorized to grant Awards to any “executive officer” of the Company (as defined by Rule 3b-7 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) or to any “officer” of the Company (as defined by Rule 16a-1 under the
Exchange Act). 
 4. Stock Available for Awards. 

(a) Number of Shares. Subject to adjustment under Section 8, Awards may be made under the Plan for up to 581,875 shares of common
stock, $0.0001 par value per share, of the Company (the “Common Stock”). If any Award expires or is terminated, surrendered or canceled without having been fully exercised, is forfeited in whole or in part (including as the result
of shares of Common Stock subject to such Award being repurchased by the Company at the original issuance price pursuant to a contractual repurchase right), or results in any Common Stock not being issued, the unused Common Stock covered by such
Award shall again be available for the grant of Awards under the Plan. Further, shares of Common Stock tendered to the Company by a Participant to exercise an Award shall be added to the number of shares of Common Stock available for the grant of
Awards under the Plan. However, in the case of Incentive Stock Options (as hereinafter defined), the foregoing provisions shall be subject to any limitations under the Code. Shares issued under the Plan may consist in whole or in part of authorized
but unissued shares or treasury shares. 
 (b) Substitute Awards. In connection with a merger or consolidation of an entity with the
Company or the acquisition by the Company of property or stock of an entity, the Board may grant Awards in substitution for any options or other stock or stock-based awards granted by such entity or an affiliate thereof. Substitute Awards may be
granted on such terms as the Board deems appropriate in the circumstances, notwithstanding any limitations on Awards contained in the Plan. Substitute Awards shall not count against the overall share limit set forth in Section 4(a), except as
may be required by reason of Section 422 and related provisions of the Code. 
 5. Stock Options 

(a) General. The Board may grant options to purchase Common Stock (each, an “Option”) and determine the number of
shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of each Option, including conditions relating to applicable federal or state securities laws, as it
considers necessary or advisable. An Option that is not intended to be an Incentive Stock Option shall be designated a “Nonstatutory Stock Option”. 

  
 2 

 (b) Incentive Stock Options. An Option that the Board intends to be an “incentive
stock option” as defined in Section 422 of the Code (an “Incentive Stock Option”) shall only be granted to employees of the Company, any of the Company’s present or future parent or subsidiary corporations as defined
in Sections 424(e) or (f) of the Code, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code, and shall be subject to and shall be construed consistently with the requirements of
Section 422 of the Code. The Company shall have no liability to a Participant, or any other party, if an Option (or any part thereof) that is intended to be an Incentive Stock Option is not an Incentive Stock Option or for any action taken by
the Board, including without limitation the conversion of an Incentive Stock Option to a Nonstatutory Stock Option. 
 (c) Exercise
Price. The Board shall establish the exercise price of each Option and specify the exercise price in the applicable option agreement. The exercise price shall be not less than 100% of the Fair Market Value (as defined below) on the date the
Option is granted. 
 (d) Duration of Options. Each Option shall be exercisable at such times and subject to such terms and conditions
as the Board may specify in the applicable option agreement. 
 (e) Exercise of Options. Options may be exercised by delivery to the
Company of a written notice of exercise signed by the proper person or by any other form of notice (including electronic notice) approved by the Board together with payment in full as specified in Section 5(f) for the number of shares for which
the Option is exercised. Shares of Common Stock subject to the Option will be delivered by the Company as soon as practicable following exercise. 

(f) Payment Upon Exercise. Common Stock purchased upon the exercise of an Option granted under the Plan shall be paid for as follows:

 (1) in cash or by check, payable to the order of the Company; 

(2) when the Common Stock is registered under the Exchange Act, except as may otherwise be provided in the applicable option agreement, by
(i) delivery of an irrevocable and unconditional undertaking by a creditworthy broker to deliver promptly to the Company sufficient funds to pay the exercise price and any required tax withholding or (ii) delivery by the Participant to the
Company of a copy of irrevocable and unconditional instructions to a creditworthy broker to deliver promptly to the Company cash or a check sufficient to pay the exercise price and any required tax withholding; 

(3) when the Common Stock is registered under the Exchange Act and to the extent provided for in the applicable option agreement or approved by
the Board, in its sole discretion, by delivery (either by actual delivery or attestation) of shares of Common Stock owned by the Participant valued at their fair market value as determined by (or in a manner approved by) the Board (“Fair
Market Value”), provided (i) such method of payment is then permitted under applicable law, (ii) such Common Stock, if acquired directly from the Company, was owned by the Participant for such minimum period of time, if any, as
may be established by the Board in its discretion and (iii) such Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements; 

(4) to the extent permitted by applicable law and provided for in the applicable option agreement or approved by the Board, in its sole
discretion, by (i) delivery of a promissory note of the Participant to the Company on terms determined by the Board, or (ii) payment of such other lawful consideration as the Board may determine; or 

  
 3 

 (5) by any combination of the above permitted forms of payment. 

6. Restricted Stock; Restricted Stock Units 

(a) General. The Board may grant Awards entitling recipients to acquire shares of Common Stock (“Restricted Stock”),
subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost) from the recipient in the event that conditions
specified by the Board in the applicable Award are not satisfied prior to the end of the applicable restriction period or periods established by the Board for such Award. Instead of granting Awards for Restricted Stock, the Board may grant Awards
entitling the recipient to receive shares of Common Stock or cash to be delivered at the time such Award vests (“Restricted Stock Units”) (Restricted Stock and Restricted Stock Units are each referred to herein as a
“Restricted Stock Award”). 
 (b) Terms and Conditions for All Restricted Stock Awards. The Board shall determine the
terms and conditions of a Restricted Stock Award, including the conditions for vesting and repurchase (or forfeiture) and the issue price, if any. 

(c) Additional Provisions Relating to Restricted Stock. 

(1) Dividends. Participants holding shares of Restricted Stock will be entitled to all ordinary cash dividends paid with respect to such
shares, unless otherwise provided by the Board. Unless otherwise provided, by the Board, if any dividends or distributions are paid in shares, or consist of a dividend or distribution to holders of Common Stock other than an ordinary cash dividend,
the shares, cash or other property will be subject to the same restrictions on transferability and forfeitability as the shares of Restricted Stock with respect to which they were paid. Each dividend payment will be made no later than the end of the
calendar year in which the dividends are paid to shareholders of that class of stock or, if later, the 15th day of the third month following the date the dividends are paid to shareholders of that class of stock. 

(2) Stock Certificates. The Company may require that any stock certificates issued in respect of shares of Restricted Stock shall be
deposited in escrow by the Participant, together with a stock power endorsed in blank, with the Company (or its designee). At the expiration of the applicable restriction periods, the Company (or such designee) shall deliver the certificates no
longer subject to such restrictions to the Participant or if the Participant has died, to the beneficiary designated, in a manner determined by the Board, by a Participant to receive amounts due or exercise rights of the Participant in the event of
the Participant’s death (the “Designated Beneficiary”). In the absence of an effective designation by a Participant, “Designated Beneficiary” shall mean the Participant’s estate. 

  
 4 

 7. Other Stock-Based Awards 

Other Awards of shares of Common Stock, and other Awards that are valued in whole or in part by reference to, or are otherwise based on, shares
of Common Stock or other property, may be granted hereunder to Participants (“Other Stock-Based Awards”), including without limitation stock appreciation rights (“SARs”) and Awards entitling recipients to receive
shares of Common Stock to be delivered in the future. Such Other Stock-Based Awards shall also be available as a form of payment in the settlement of other Awards granted under the Plan or as payment in lieu of compensation to which a Participant is
otherwise entitled. Other Stock-Based Awards may be paid in shares of Common Stock or cash, as the Board shall determine. Subject to the provisions of the Plan, the Board shall determine the terms and conditions of each Other Stock-Based Award,
including any purchase price applicable thereto. 
 8. Adjustments for Changes in Common Stock and Certain Other Events 

(a) Changes in Capitalization. In the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of
shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of Common Stock other than an ordinary cash dividend, (i) the
number and class of securities available under this Plan, (ii) the number and class of securities and exercise price per share of each outstanding Option, (iii) the number of shares subject to and the repurchase price per share subject to
each outstanding Restricted Stock Award, and (iv) the terms of each other outstanding Award shall be equitably adjusted by the Company (or substituted Awards may be made, if applicable) in the manner determined by the Board. Without limiting
the generality of the foregoing, in the event the Company effects a split of the Common Stock by means of a stock dividend and the exercise price of and the number of shares subject to an outstanding Option are adjusted as of the date of the
distribution of the dividend (rather than as of the record date for such dividend), then an optionee who exercises an Option between the record date and the distribution date for such stock dividend shall be entitled to receive, on the distribution
date, the stock dividend with respect to the shares of Common Stock acquired upon such Option exercise, notwithstanding the fact that such shares were not outstanding as of the close of business on the record date for such stock dividend. 

(b) Reorganization Events. 

(1) Definition. A “Reorganization Event” shall mean: (a) any merger or consolidation of the Company with or into another
entity as a result of which all of the Common Stock of the Company is converted into or exchanged for the right to receive cash, securities or other property or is cancelled, (b) any exchange of all of the Common Stock of the Company for cash,
securities or other property pursuant to a share exchange transaction or (c) any liquidation or dissolution of the Company. 
 (2)
Consequences of a Reorganization Event on Awards Other than Restricted Stock Awards. In connection with a Reorganization Event, the Board may take any one or more of the following actions as to all or any (or any portion of) outstanding
Awards other than Restricted Stock Awards on such terms as the Board determines: (i) provide that Awards shall be assumed, or substantially equivalent Awards shall be substituted, by the acquiring or succeeding corporation (or an affiliate
thereof), (ii) upon written notice to a Participant, provide that the Participant’s unexercised Awards will terminate immediately prior to the consummation of such Reorganization Event unless exercised by the Participant within a specified
period following the date of such notice, (iii) provide that outstanding Awards shall become exercisable, 

  
 5 

 
realizable, or deliverable, or restrictions applicable to an Award shall lapse, in whole or in part prior to or upon such Reorganization Event, (iv) in the event of a Reorganization Event
under the terms of which holders of Common Stock will receive upon consummation thereof a cash payment for each share surrendered in the Reorganization Event (the “Acquisition Price”), make or provide for a cash payment to a Participant
equal to the excess, if any, of (A) the Acquisition Price times the number of shares of Common Stock subject to the Participant’s Awards (to the extent the exercise price does not exceed the Acquisition Price) over (B) the aggregate
exercise price of all such outstanding Awards and any applicable tax withholdings, in exchange for the termination of such Awards, (v) provide that, in connection with a liquidation or dissolution of the Company, Awards shall convert into the
right to receive liquidation proceeds (if applicable, net of the exercise price thereof and any applicable tax withholdings) and (vi) any combination of the foregoing. In taking any of the actions permitted under this Section 8(b), the
Board shall not be obligated by the Plan to treat all Awards, all Awards held by a Participant, or all Awards of the same type, identically. 

For purposes of clause (i) above, an Option shall be considered assumed if, following consummation of the Reorganization Event, the
Option confers the right to purchase, for each share of Common Stock subject to the Option immediately prior to the consummation of the Reorganization Event, the consideration (whether cash, securities or other property) received as a result of the
Reorganization Event by holders of Common Stock for each share of Common Stock held immediately prior to the consummation of the Reorganization Event (and if holders were offered a choice of consideration, the type of consideration chosen by the
holders of a majority of the outstanding shares of Common Stock); provided, however, that if the consideration received as a result of the Reorganization Event is not solely common stock of the acquiring or succeeding corporation (or an affiliate
thereof), the Company may, with the consent of the acquiring or succeeding corporation, provide for the consideration to be received upon the exercise of Options to consist solely of common stock of the acquiring or succeeding corporation (or an
affiliate thereof) equivalent in value (as determined by the Board) to the per share consideration received by holders of outstanding shares of Common Stock as a result of the Reorganization Event. 

(3) Consequences of a Reorganization Event on Restricted Stock Awards. Upon the occurrence of a Reorganization Event other than a
liquidation or dissolution of the Company, the repurchase and other rights of the Company under each outstanding Restricted Stock Award shall inure to the benefit of the Company’s successor and shall, unless the Board determines otherwise,
apply to the cash, securities or other property which the Common Stock was converted into or exchanged for pursuant to such Reorganization Event in the same manner and to the same extent as they applied to the Common Stock subject to such Restricted
Stock Award. Upon the occurrence of a Reorganization Event involving the liquidation or dissolution of the Company, except to the extent specifically provided to the contrary in the instrument evidencing any Restricted Stock Award or any other
agreement between a Participant and the Company, all restrictions and conditions on all Restricted Stock Awards then outstanding shall automatically be deemed terminated or satisfied. 

  
 6 

 9. General Provisions Applicable to Awards 

(a) Transferability of Awards. Except as the Board may otherwise determine or provide in an Award, Awards shall not be sold, assigned,
transferred, pledged or otherwise encumbered by the person to whom they are granted, either voluntarily or by operation of law, except by will or the laws of descent and distribution or, other than in the case of an Incentive Stock Option, pursuant
to a qualified domestic relations order, and, during the life of the Participant, shall be exercisable only by the Participant. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees.

 (b) Documentation. Each Award shall be evidenced in such form (written, electronic or otherwise) as the Board shall determine. Each
Award may contain terms and conditions in addition to those set forth in the Plan. 
 (c) Board Discretion. Except as otherwise
provided by the Plan, each Award may be made alone or in addition or in relation to any other Award. The terms of each Award need not be identical, and the Board need not treat Participants uniformly. 

(d) Termination of Status. The Board shall determine the effect on an Award of the disability, death, termination or other cessation of
employment, authorized leave of absence or other change in the employment or other status of a Participant and the extent to which, and the period during which, the Participant, or the Participant’s legal representative, conservator, guardian
or Designated Beneficiary, may exercise rights under the Award.  
 (e)
Withholding. The Participant must satisfy all applicable federal, state, and local or other income and employment tax withholding obligations before the Company will deliver stock certificates or otherwise recognize ownership of Common Stock
under an Award. The Company may decide to satisfy the withholding obligations through additional withholding on salary or wages. If the Company elects not to or cannot withhold from other compensation, the Participant must pay the Company the full
amount, if any, required for withholding or have a broker tender to the Company cash equal to the withholding obligations. Payment of withholding obligations is due before the Company will issue any shares on exercise or release from forfeiture of
an Award or, if the Company so requires, at the same time as payment of the exercise price unless the Company determines otherwise. If provided for in an Award or approved by the Board in its sole discretion, a Participant may satisfy such tax
obligations in whole or in part by delivery of shares of Common Stock, including shares retained from the Award creating the tax obligation, valued at their Fair Market Value; provided, however, except as otherwise provided by the Board, that the
total tax withholding where stock is being used to satisfy such tax obligations cannot exceed the Company’s minimum statutory withholding obligations (based on minimum statutory withholding rates for federal and state tax purposes, including
payroll taxes, that are applicable to such supplemental taxable income). Shares surrendered to satisfy tax withholding requirements cannot be subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements. 

  
 7 

 (f) Amendment of Award. 

(1) The Board may amend, modify or terminate any outstanding Award, including but not limited to, substituting therefor another Award of the
same or a different type, changing the date of exercise or realization, and converting an Incentive Stock Option to a Nonstatutory Stock Option. The Participant’s consent to such action shall be required unless (i) the Board determines
that the action, taking into account any related action, would not materially and adversely affect the Participant’s rights under the Plan or (ii) the change is permitted under Section 8 hereof. 

(2) The Board may, without stockholder approval, amend any outstanding Award granted under the Plan to provide an exercise price per share that
is lower than the then-current exercise price per share of such outstanding Award. The Board may also, without stockholder approval, cancel any outstanding award (whether or not granted under the Plan) and grant in substitution therefor new Awards
under the Plan covering the same or a different number of shares of Common Stock and having an exercise price per share lower than the then-current exercise price per share of the cancelled award. 

(g) Conditions on Delivery of Stock. The Company will not be obligated to deliver any shares of Common Stock pursuant to the Plan or to
remove restrictions from shares previously delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company, (ii) in the opinion of the Company’s counsel, all other legal
matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and any applicable stock exchange or stock market rules and regulations, and (iii) the Participant has executed
and delivered to the Company such representations or agreements as the Company may consider appropriate to satisfy the requirements of any applicable laws, rules or regulations. 

(h) Acceleration. The Board may at any time provide that any Award shall become immediately exercisable in full or in part, free of some
or all restrictions or conditions, or otherwise realizable in full or in part, as the case may be. 
 10. Miscellaneous 

(a) No Right to Employment or Other Status. No person shall have any claim or right to be granted an Award, and the grant of an Award
shall not be construed as giving a Participant the right to continued employment or any other relationship with the Company. The Company expressly reserves the right at any time to dismiss or otherwise terminate its relationship with a Participant
free from any liability or claim under the Plan, except as expressly provided in the applicable Award. 
 (b) No Rights as
Stockholder. Subject to the provisions of the applicable Award, no Participant or Designated Beneficiary shall have any rights as a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming
the record holder of such shares. 
 (c) Effective Date and Term of Plan. The Plan shall become effective on the date on which it is
adopted by the Board. No Awards shall be granted under the Plan after the expiration of 10 years from the earlier of (i) the date on which the Plan was adopted by the Board or (ii) the date the Plan was approved by the Company’s
stockholders, but Awards previously granted may extend beyond that date. 

  
 8 

 (d) Amendment of Plan. The Board may amend, suspend or terminate the Plan or any portion
thereof at any time; provided that if at any time the approval of the Company’s stockholders is required as to any modification or amendment under Section 422 of the Code or any successor provision with respect to Incentive Stock Options,
the Board may not effect such modification or amendment without such approval. Unless otherwise specified in the amendment, any amendment to the Plan adopted in accordance with this Section 10(d) shall apply to, and be binding on the holders
of, all Awards outstanding under the Plan at the time the amendment is adopted, provided the Board determines that such amendment does not materially and adversely affect the rights of Participants under the Plan. 

(e) Authorization of Sub-Plans. The Board may from time to time establish one or more sub-plans under the Plan for purposes of satisfying applicable blue sky, securities or tax laws of various jurisdictions. The Board shall establish such sub-plans by adopting
supplements to this Plan containing (i) such limitations on the Board’s discretion under the Plan as the Board deems necessary or desirable or (ii) such additional terms and conditions not otherwise inconsistent with the Plan as the
Board shall deem necessary or desirable. All supplements adopted by the Board shall be deemed to be part of the Plan, but each supplement shall apply only to Participants within the affected jurisdiction and the Company shall not be required to
provide copies of any supplement to Participants in any jurisdiction which is not the subject of such supplement. 
 (f) Compliance with
Code Section 409A. No Award shall provide for deferral of compensation that does not comply with Section 409A of the Code, unless the Board, at the time of grant, specifically provides that the Award is not intended to
comply with Section 409A of the Code. The Company shall have no liability to a Participant, or any other party, if an Award that is intended to be exempt from, or compliant with, Section 409A is not so exempt or compliant or for any action
taken by the Board. 
 (g) Governing Law. The provisions of the Plan and all Awards made hereunder shall be governed by and
interpreted in accordance with the laws of the State of Delaware, excluding choice-of-law principles of the law of such state that would require the application of the
laws of a jurisdiction other than such state. 

  
 9 

 RESTORBIO, INC. 

Restricted Stock Agreement 

Granted Under 2017 Stock Incentive Plan 

AGREEMENT made this [            ] day of
[                    ], 20[         ], between resTORbio, Inc., a Delaware corporation
(the “Company”), and [                            ] (the “Participant”). 

For valuable consideration, receipt of which is acknowledged, the parties hereto agree as follows: 

1. Purchase of Shares. 

The Company shall issue and sell to the Participant, and the Participant shall purchase from the Company, subject to the terms and conditions
set forth in this Agreement and in the Company’s 2017 Stock Incentive Plan (the “Plan”), [______] shares (the “Shares”) of common stock, $0.0001 par value, of the Company (“Common Stock”), at a purchase price of $[
] per share. The aggregate purchase price for the Shares shall be paid by the Participant by check payable to the order of the Company or such other method as may be acceptable to the Company. Upon receipt by the Company of payment for the
Shares, the Company shall issue to the Participant one or more certificates in the name of the Participant for that number of Shares purchased by the Participant. The Participant agrees that the Shares shall be subject to the purchase options set
forth in Sections 2 and 5 of this Agreement and the restrictions on transfer set forth in Section 4 of this Agreement. 
 2.
Purchase Option. 
 (a) In the event that the Participant ceases to be employed by the Company for any reason or no reason, with or
without cause, prior to [            ], the Company shall have the right and option (the “Purchase Option”) to purchase from the Participant, for a sum of $[__] per share
(the “Option Price”), some or all of the Unvested Shares (as defined below). 
 “Unvested Shares” means the total number
of Shares multiplied by the Applicable Percentage at the time the Purchase Option becomes exercisable by the Company. The “Applicable Percentage” shall be (i) 100% during the 12-month period
ending [                    ], 20[ ], (ii) [75%] less [12.5%] for each [six] months of employment completed by the Participant with the
Company from and after [        ], 20[ ], and (iii) zero on or after [                ],
20[        ]. 
 (b) If the Participant is employed by a parent or subsidiary of the Company,
any references in this Agreement to employment with the Company or termination of employment by or with the Company shall instead be deemed to refer to such parent or subsidiary. 

 3. Exercise of Purchase Option and Closing. 

(a) The Company may exercise the Purchase Option by delivering or mailing to the Participant (or his estate), within 90 days after the
termination of the employment of the Participant with the Company, a written notice of exercise of the Purchase Option. Such notice shall specify the number of Shares to be purchased. If and to the extent the Purchase Option is not so exercised by
the giving of such a notice within such 90-day period, the Purchase Option shall automatically expire and terminate effective upon the expiration of such 90-day period.

 (b) Within 10 days after delivery to the Participant of the Company’s notice of the exercise of the Purchase Option pursuant to
subsection (a) above, the Participant (or his estate) shall, pursuant to the provisions of the Joint Escrow Instructions referred to in Section 7 below, tender to the Company at its principal offices the certificate or certificates
representing the Shares which the Company has elected to purchase in accordance with the terms of this Agreement, duly endorsed in blank or with duly endorsed stock powers attached thereto, all in form suitable for the transfer of such Shares to the
Company. Promptly following its receipt of such certificate or certificates, the Company shall pay to the Participant the aggregate Option Price for such Shares (provided that any delay in making such payment shall not invalidate the Company’s
exercise of the Purchase Option with respect to such Shares). 
 (c) After the time at which any Shares are required to be delivered to the
Company for transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Shares or permit the Participant to exercise any of the privileges or rights of a stockholder
with respect to such Shares, but shall, in so far as permitted by law, treat the Company as the owner of such Shares. 
 (d) The Option Price
may be payable, at the option of the Company, in cancellation of all or a portion of any outstanding indebtedness of the Participant to the Company or in cash (by check) or both. 

(e) The Company shall not purchase any fraction of a Share upon exercise of the Purchase Option, and any fraction of a Share resulting from a
computation made pursuant to Section 2 of this Agreement shall be rounded to the nearest whole Share (with any one-half Share being rounded upward). 

(f) The Company may assign its Purchase Option to one or more persons or entities. 

4. Restrictions on Transfer. 

(a) The Participant shall not sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of law or otherwise
(collectively “transfer”) any Shares, or any interest therein, that are subject to the Purchase Option, except that the Participant may transfer such Shares (i) to or for the benefit of any spouse, children, parents, uncles, aunts,
siblings, grandchildren and any other relatives approved by the Board of Directors (collectively, “Approved Relatives”) or to a trust established solely for the benefit of the Participant and/or

  
 - 2 - 

 
Approved Relatives, provided that such Shares shall remain subject to this Agreement (including without limitation the restrictions on transfer set forth in this Section 4, the
Purchase Option and the right of first refusal set forth in Section 5) and such permitted transferee shall, as a condition to such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of
the terms and conditions of this Agreement or (ii) as part of the sale of all or substantially all of the shares of capital stock of the Company (including pursuant to a merger or consolidation), provided that, in accordance with the
Plan, the securities or other property received by the Participant in connection with such transaction shall remain subject to this Agreement. 

(b) The Participant shall not transfer any Shares, or any interest therein, that are no longer subject to the Purchase Option, except in
accordance with Section 5 below. 
 5. Right of First Refusal. 

(a) If the Participant proposes to transfer any Shares that are no longer subject to the Purchase Option (either because they are no longer
Unvested Shares or because the Purchase Option expired unexercised), then the Participant shall first give written notice of the proposed transfer (the “Transfer Notice”) to the Company. The Transfer Notice shall name the proposed
transferee and state the number of such Shares the Participant proposes to transfer (the “Offered Shares”), the price per share and all other material terms and conditions of the transfer. 

(b) For 30 days following its receipt of such Transfer Notice, the Company shall have the option to purchase all or part of the Offered Shares
at the price and upon the terms set forth in the Transfer Notice. In the event the Company elects to purchase all or part of the Offered Shares, it shall give written notice of such election to the Participant within such 30-day period. Within 10 days after his or her receipt of such notice, the Participant shall tender to the Company at its principal offices the certificate or certificates representing the Offered Shares to be
purchased by the Company, duly endorsed in blank by the Participant or with duly endorsed stock powers attached thereto, all in a form suitable for transfer of the Offered Shares to the Company. Promptly following receipt of such certificate or
certificates, the Company shall deliver or mail to the Participant a check in payment of the purchase price for such Offered Shares; provided that if the terms of payment set forth in the Transfer Notice were other than cash against
delivery, the Company may pay for the Offered Shares on the same terms and conditions as were set forth in the Transfer Notice; and provided further that any delay in making such payment shall not invalidate the Company’s exercise
of its option to purchase the Offered Shares. 
 (c) If the Company does not elect to acquire all of the Offered Shares, the Participant may,
within the 30-day period following the expiration of the option granted to the Company under subsection (b) above, transfer the Offered Shares which the Company has not elected to acquire to the proposed
transferee, provided that such transfer shall not be on terms and conditions more favorable to the transferee than those contained in the Transfer Notice. Notwithstanding any of the above, all Offered Shares transferred pursuant to
this Section 5 shall remain subject to this Agreement (including without limitation the restrictions on transfer set forth in Section 4 and the right of first refusal set forth in this Section 5) and such transferee shall, as a
condition to such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement. 

  
 - 3 - 

 (d) After the time at which the Offered Shares are required to be delivered to the Company for
transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Offered Shares or permit the Participant to exercise any of the privileges or rights of a stockholder with
respect to such Offered Shares, but shall, insofar as permitted by law, treat the Company as the owner of such Offered Shares. 
 (e) The
following transactions shall be exempt from the provisions of this Section 5: 
 (1) a transfer of Shares to or for the benefit of any
Approved Relatives, or to a trust established solely for the benefit of the Participant and/or Approved Relatives; 
 (2) any transfer
pursuant to an effective registration statement filed by the Company under the Securities Act of 1933, as amended (the “Securities Act”); and 

(3) the sale of all or substantially all of the outstanding shares of capital stock of the Company (including pursuant to a merger or
consolidation); 
 provided, however, that in the case of a transfer pursuant to clause (1) above, such Shares shall remain subject to this
Agreement (including without limitation the restrictions on transfer set forth in Section 4 and the right of first refusal set forth in this Section 5) and such transferee shall, as a condition to such transfer, deliver to the Company a
written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Agreement. 
 (f) The Company
may assign its rights to purchase Offered Shares in any particular transaction under this Section 5 to one or more persons or entities. 

(g) The provisions of this Section 5 shall terminate upon the earlier of the following events: 

(1) the closing of the sale of shares of Common Stock in an underwritten public offering pursuant to an effective registration statement filed
by the Company under the Securities Act; or 
 (2) the sale of all or substantially all of the outstanding shares of capital stock, assets
or business of the Company, by merger, consolidation, sale of assets or otherwise (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the Company’s voting
securities immediately prior to such transaction beneficially own, directly or indirectly, more than 50% (determined on an as-converted basis) of the outstanding securities entitled to vote generally in the
election of directors of the resulting, surviving or acquiring corporation in such transaction). 

  
 - 4 - 

 (h) The Company shall not be required (1) to transfer on its books any of the Shares which
shall have been sold or transferred in violation of any of the provisions set forth in this Agreement, or (2) to treat as owner of such Shares or to pay dividends to any transferee to whom any such Shares shall have been so sold or transferred.

 6. Agreement in Connection with Initial Public Offering. 

The Participant agrees, in connection with the initial underwritten public offering of the Common Stock pursuant to a registration statement
under the Securities Act, (i) not to (a) offer, pledge, announce the intention to sell, 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 for shares of Common Stock or (b) enter into any swap or other agreement that
transfers, in whole or in part, any of the economic consequences of ownership of shares of Common Stock, whether any transaction described in clause (a) or (b) is to be settled by delivery of shares of Common Stock or other securities, in cash
or otherwise, during the period beginning on the date of the filing of such registration statement with the Securities and Exchange Commission and ending 180 days from the date of the final prospectus relating to the offering (plus up to an
additional 34 days to the extent requested by the managing underwriters for such offering in order to address Rule 2711(f) of the National Association of Securities Dealers, Inc. or any similar successor provision), and (ii) to execute any
agreement reflecting clause (i) above as may be requested by the Company or the managing underwriters at the time of such offering. The Company may impose stop-transfer instructions with respect to the shares of Common Stock or other securities
subject to the foregoing restriction until the end of the “lock-up” period. 
 7.
Escrow. 
 The Participant shall, upon the execution of this Agreement, execute Joint Escrow Instructions in the form attached to this
Agreement as Exhibit A. The Joint Escrow Instructions shall be delivered to the President of the Company, as escrow agent thereunder. The Participant shall deliver to such escrow agent a stock assignment duly endorsed in blank, in the form
attached to this Agreement as Exhibit B, and hereby instructs the Company to deliver to such escrow agent, on behalf of the Participant, the certificate(s) evidencing the Shares issued hereunder. Such materials shall be held by such escrow
agent pursuant to the terms of such Joint Escrow Instructions. 
 8. Restrictive Legends. 

All certificates representing Shares shall have affixed thereto legends in substantially the following form, in addition to any other legends
that may be required under federal or state securities laws: 
 “The shares of stock represented by this certificate are subject to
restrictions on transfer and an option to purchase set forth in a certain Restricted Stock Agreement between the corporation and the registered owner of these shares (or his predecessor in interest), and such Agreement is available for inspection
without charge at the office of the Secretary of the corporation.” 

  
 - 5 - 

 “The shares represented by this certificate have not been registered under the Securities
Act of 1933, as amended, and may not be sold, transferred or otherwise disposed of in the absence of an effective registration statement under such Act or an opinion of counsel satisfactory to the corporation to the effect that such registration is
not required.” 
 9. Provisions of the Plan. 

(a) This Agreement is subject to the provisions of the Plan, a copy of which is furnished to the Participant with this Agreement. 

(b) As provided in the Plan, upon the occurrence of a Reorganization Event (as defined in the Plan), the repurchase and other rights of the
Company hereunder shall inure to the benefit of the Company’s successor and shall apply to the cash, securities or other property which the Shares were converted into or exchanged for pursuant to such Reorganization Event in the same manner and
to the same extent as they applied to the Shares under this Agreement. If, in connection with a Reorganization Event, a portion of the cash, securities and/or other property received upon the conversion or exchange of the Shares is to be placed into
escrow to secure indemnification or similar obligations, the mix between the vested and unvested portion of such cash, securities and/or other property that is placed into escrow shall be the same as the mix between the vested and unvested portion
of such cash, securities and/or other property that is not subject to escrow. 
 10. Investment Representations. 

The Participant represents, warrants and covenants as follows: 

(a) The Participant is purchasing the Shares for his own account for investment only, and not with a view to, or for sale in connection with,
any distribution of the Shares in violation of the Securities Act, or any rule or regulation under the Securities Act. 
 (b) The Participant
has had such opportunity as he has deemed adequate to obtain from representatives of the Company such information as is necessary to permit him to evaluate the merits and risks of his investment in the Company. 

(c) The Participant has sufficient experience in business, financial and investment matters to be able to evaluate the risks involved in the
purchase of the Shares and to make an informed investment decision with respect to such purchase. 
 (d) The Participant can afford a
complete loss of the value of the Shares and is able to bear the economic risk of holding such Shares for an indefinite period. 

  
 - 6 - 

 (e) The Participant understands that (i) the Shares have not been registered under the
Securities Act and are “restricted securities” within the meaning of Rule 144 under the Securities Act; (ii) the Shares cannot be sold, transferred or otherwise disposed of unless they are subsequently registered under the
Securities Act or an exemption from registration is then available; (iii) in any event, the exemption from registration under Rule 144 will not be available for at least one year and even then will not be available unless a public market
then exists for the Common Stock, adequate information concerning the Company is then available to the public, and other terms and conditions of Rule 144 are complied with; and (iv) there is now no registration statement on file with the
Securities and Exchange Commission with respect to any stock of the Company and the Company has no obligation or current intention to register the Shares under the Securities Act. 

11. Withholding Taxes; Section 83(b) Election. 

(a) The Participant acknowledges and agrees that the Company has the right to deduct from payments of any kind otherwise due to the Participant
any federal, state or local taxes of any kind required by law to be withheld with respect to the purchase of the Shares by the Participant or the lapse of the Purchase Option. 

(b) The Participant has reviewed with the Participant’s own tax advisors the federal, state, local and foreign tax consequences of this
investment and the transactions contemplated by this Agreement. The Participant is relying solely on such advisors and not on any statements or representations of the Company or any of its agents. The Participant understands that the Participant
(and not the Company) shall be responsible for the Participant’s own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. The Participant understands that it may be beneficial in many
circumstances to elect to be taxed at the time the Shares are purchased rather than when and as the Company’s Purchase Option expires by filing an election under Section 83(b) of the Internal Revenue Code of 1986 with the I.R.S. within 30
days from the date of purchase. 
 THE PARTICIPANT ACKNOWLEDGES THAT IT IS SOLELY THE PARTICIPANT’S RESPONSIBILITY AND NOT THE
COMPANY’S TO FILE TIMELY THE ELECTION UNDER SECTION 83(b), EVEN IF THE PARTICIPANT REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO MAKE THIS FILING ON THE PARTICIPANT’S BEHALF. 

12. Miscellaneous. 
 (a)
No Rights to Employment. The Participant acknowledges and agrees that the vesting of the Shares pursuant to Section 2 hereof is earned only by continuing service as an employee at the will of the Company (not through the act of being
hired or purchasing shares hereunder). The Participant further acknowledges and agrees that the transactions contemplated hereunder and the vesting schedule set forth herein do not constitute an express or implied promise of continued engagement as
an employee or consultant for the vesting period, for any period, or at all. 

  
 - 7 - 

 (b) Severability. The invalidity or unenforceability of any provision of this Agreement
shall not affect the validity or enforceability of any other provision of this Agreement, and each other provision of this Agreement shall be severable and enforceable to the extent permitted by law. 

(c) Waiver. Any provision for the benefit of the Company contained in this Agreement may be waived, either generally or in any
particular instance, by the Board of Directors of the Company. 
 (d) Binding Effect. This Agreement shall be binding upon and inure
to the benefit of the Company and the Participant and their respective heirs, executors, administrators, legal representatives, successors and assigns, subject to the restrictions on transfer set forth in Sections 4 and 5 of this Agreement.

 (e) Notice. All notices required or permitted hereunder shall be in writing and deemed effectively given upon personal delivery or
five days after deposit in the United States Post Office, by registered or certified mail, postage prepaid, addressed to the other party hereto at the address shown beneath his or its respective signature to this Agreement, or at such other address
or addresses as either party shall designate to the other in accordance with this Section 12(e). 
 (f) Pronouns. Whenever the
context may require, any pronouns used in this Agreement shall include the corresponding masculine, feminine or neuter forms, and the singular form of nouns and pronouns shall include the plural, and vice versa. 

(g) Entire Agreement. This Agreement and the Plan constitute the entire agreement between the parties, and supersedes all prior
agreements and understandings, relating to the subject matter of this Agreement. 
 (h) Amendment. This Agreement may be amended or
modified only by a written instrument executed by both the Company and the Participant. 
 (i) Governing Law. This Agreement shall be
construed, interpreted and enforced in accordance with the internal laws of the State of Delaware without regard to any applicable conflicts of laws. 

(j) Participant’s Acknowledgments. The Participant acknowledges that he or she: (i) has read this Agreement; (ii) has
been represented in the preparation, negotiation, and execution of this Agreement by legal counsel of the Participant’s own choice or has voluntarily declined to seek such counsel; (iii) understands the terms and consequences of this
Agreement; (iv) is fully aware of the legal and binding effect of this Agreement; and (v) understands that the law firm of WilmerHale, is acting as counsel to the Company in connection with the transactions contemplated by the Agreement,
and is not acting as counsel for the Participant. 

  
 - 8 - 

 IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first
above written. 
  

			
	RESTORBIO, INC.

 
			
		
	By:	 	  

	Name:	 	
	Title:	 	

  

	
	PARTICIPANT:
	  

	[Name of Participant]

  

			
	Address:	 	  

		 	  

  
 - 9 - 

 Exhibit A 

RESTORBIO, INC. 
 Joint Escrow
Instructions 

                    ,
[        ] 
 resTORbio, Inc. 

President 
 501 Boylston Street, Suite 6102 

Boston, MA 02116 
 Dear Sir or Madam: 

As Escrow Agent for resTORbio, Inc., a Delaware corporation, and its successors in interest (the “Company”) under the Restricted
Stock Agreement (the “Agreement”) of even date herewith, to which a copy of these Joint Escrow Instructions is attached, and the undersigned person (“Holder”), you are hereby authorized and directed to hold the documents
delivered to you pursuant to the terms of the Agreement in accordance with the following instructions: 
 1. Appointment. Holder
irrevocably authorizes the Company to deposit with you any certificates evidencing Shares (as defined in the Agreement) to be held by you hereunder and any additions and substitutions to said Shares. For purposes of these Joint Escrow Instructions,
“Shares” shall be deemed to include any additional or substitute property. Holder does hereby irrevocably constitute and appoint you as his attorney-in-fact
and agent for the term of this escrow to execute with respect to such Shares all documents necessary or appropriate to make such Shares negotiable and to complete any transaction herein contemplated. Subject to the provisions of this Section 1
and the terms of the Agreement, Holder shall exercise all rights and privileges of a stockholder of the Company while the Shares are held by you. 

2. Closing of Purchase. 

(a) Upon any purchase by the Company of the Shares pursuant to the Agreement, the Company shall give to Holder and you a written notice
specifying the number of Shares to be purchased, the purchase price for the Shares, as determined pursuant to the Agreement, and the time for a closing hereunder (the “Closing”) at the principal office of the Company. Holder and the
Company hereby irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice. 

(b) At the Closing, you are directed (i) to date the stock assignment form or forms necessary for the transfer of the Shares, (ii) to
fill in on such form or forms the number of Shares being transferred, and (iii) to deliver the same, together with the certificate or certificates evidencing the Shares to be transferred, to the Company against the simultaneous delivery to you
of the purchase price for the Shares being purchased pursuant to the Agreement. 

  
 - 10 - 

 3. Withdrawal. The Holder shall have the right to withdraw from this escrow any Shares as
to which the Purchase Option (as defined in the Agreement) has terminated or expired. 
 4. Duties of Escrow Agent. 

(a) Your duties hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties hereto. 

(b) You shall be obligated only for the performance of such duties as are specifically set forth herein and may rely and shall be protected in
relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by the proper party or parties. You shall not be personally liable for any act you may do or omit to do hereunder as
Escrow Agent or as attorney-in-fact of Holder while acting in good faith and in the exercise of your own good judgment, and any act done or omitted by you pursuant to
the advice of your own attorneys shall be conclusive evidence of such good faith. 
 (c) You are hereby expressly authorized to disregard any
and all warnings given by any of the parties hereto or by any other person or entity, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. If you
are uncertain of any actions to be taken or instructions to be followed, you may refuse to act in the absence of an order, judgment or decrees of a court. In case you obey or comply with any such order, judgment or decree of any court, you shall not
be liable to any of the parties hereto or to any other person or entity, by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have been
entered without jurisdiction. 
 (d) You shall not be liable in any respect on account of the identity, authority or rights of the parties
executing or delivering or purporting to execute or deliver the Agreement or any documents or papers deposited or called for hereunder. 

(e) You shall be entitled to employ such legal counsel and other experts as you may deem necessary properly to advise you in connection with
your obligations hereunder and may rely upon the advice of such counsel. 
 (f) Your rights and responsibilities as Escrow Agent hereunder
shall terminate if (i) you cease to be Secretary of the Company or (ii) you resign by written notice to each party. In the event of a termination under clause (i), your successor as Secretary shall become Escrow Agent hereunder; in
the event of a termination under clause (ii), the Company shall appoint a successor Escrow Agent hereunder. 
 (g) If you reasonably
require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect hereto, the necessary parties hereto shall join in furnishing such instruments. 

  
 - 11 - 

 (h) It is understood and agreed that if you believe a dispute has arisen with respect to the
delivery and/or ownership or right of possession of the securities held by you hereunder, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities until such dispute shall have been
settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but you shall be under no duty
whatsoever to institute or defend any such proceedings. 
 (i) These Joint Escrow Instructions set forth your sole duties with respect to any
and all matters pertinent hereto and no implied duties or obligations shall be read into these Joint Escrow Instructions against you. 
 (j)
The Company shall indemnify you and hold you harmless against any and all damages, losses, liabilities, costs, and expenses, including attorneys’ fees and disbursements, (including without limitation the fees of counsel retained pursuant to
Section 4(e) above, for anything done or omitted to be done by you as Escrow Agent in connection with this Agreement or the performance of your duties hereunder, except such as shall result from your gross negligence or willful misconduct. 

5. Notice. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given upon personal
delivery or upon deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to each of the other parties thereunto entitled at the following addresses, or at such other addresses as a party may
designate by ten days’ advance written notice to each of the other parties hereto. 
  

					
		 	COMPANY:	  	Notices to the Company shall be sent to the address set forth in the salutation hereto, Attn: President
			
		 	HOLDER:	  	Notices to Holder shall be sent to the address set forth below Holder’s signature below.
			
		 	ESCROW AGENT:	  	Notices to the Escrow Agent shall be sent to the address set forth in the salutation hereto.

 6. Miscellaneous. 

(a) By signing these Joint Escrow Instructions, you become a party hereto only for the purpose of said Joint Escrow Instructions, and you do
not become a party to the Agreement. 
 (b) This instrument shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and permitted assigns. 

  
 - 12 - 

 
			
	Very truly yours,

  

			
	RESTORBIO, INC.

  

			
	By:	 	  

	Name:	 	
	Title:	 	

  

	
	HOLDER:
	
	  

	(Signature)
	
	  

	Print Name

  

			
	Address:	 	  

		 	  

	Date Signed:
                                         
   

 ESCROW AGENT: 

                          
                                       

  
 -13- 

 Exhibit B 

(STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE) 

FOR VALUE RECEIVED, I hereby sell, assign and transfer unto
                     (                ) shares of
Common Stock, $0.0001 par value per share, of resTORbio, Inc. (the “Corporation”) standing in my name on the books of the Corporation represented by Certificate(s) Number
                     herewith, and do hereby irrevocably constitute and appoint
                             attorney to transfer the said stock on the books of the Corporation with full
power of substitution in the premises. 
  

	
	HOLDER:
	  

	Name:
	Dated:
                                         
                           

 IN PRESENCE OF
                                         
                            

NOTICE: The signature(s) to this assignment must correspond with the name as written upon the face of the certificate, in every particular,
without alteration, enlargement, or any change whatever and must be guaranteed by a commercial bank, trust company or member firm of the Boston, New York or Midwest Stock Exchange. 

  
 - 14 - 

 RESTORBIO, INC. 

Nonstatutory Stock Option Agreement 

Granted Under 2017 Stock Incentive Plan 

1. Grant of Option. 
 This agreement
evidences the grant by resTORbio, Inc., a Delaware corporation (the “Company”), on                 ,
20[        ] (the “Grant Date”) to [             ], an [employee], [consultant],
[director] of the Company (the “Participant”), of an option to purchase, in whole or in part, on the terms provided herein and in the Company’s 2017 Stock Incentive Plan (the “Plan”), a total of
[             ] shares (the “Shares”) of common stock, $0.0001 par value per share, of the Company (“Common Stock”) at
$[                     ] per Share. Unless earlier terminated, this option shall expire at 5:00 p.m., Eastern time, on
[                ] (the “Final Exercise Date”). 

It is intended that the option evidenced by this agreement shall not be an incentive stock option as defined in Section 422 of the
Internal Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”). Except as otherwise indicated by the context, the term “Participant”, as used in this option, shall be deemed to include any
person who acquires the right to exercise this option validly under its terms. 
 2. Vesting Schedule. 

This option will become exercisable (“vest”) as to [25]% of the original number of Shares on the [first] anniversary of the Vesting
Commencement Date and as to an additional [12.5]% of the original number of Shares at the end of each successive [six-month] period following the first anniversary of the Vesting Commencement
Date until the [fourth] anniversary of the Vesting Commencement Date. The Vesting Commencement Date shall be [                    ]. 

The right of exercise shall be cumulative so that to the extent the option is not exercised in any period to the maximum extent permissible it
shall continue to be exercisable, in whole or in part, with respect to all Shares for which it is vested until the earlier of the Final Exercise Date or the termination of this option under Section 3 hereof or the Plan. 

3. Exercise of Option. 
 (a) Form of
Exercise. Each election to exercise this option shall be accompanied by a completed Notice of Stock Option Exercise in the form attached hereto as Exhibit A, signed by the Participant, and received by the Company at its principal office,
accompanied by this Agreement, and payment in full in the manner provided in the Plan. The Participant may purchase less than the number of shares covered hereby, provided that no partial exercise of this option may be for any fractional share. 

(b) Continuous Relationship with the Company Required. Except as otherwise provided in this Section 3, this option may not be
exercised unless the Participant, at the time he or she exercises this option, is, and has been at all times since the Grant Date, an [employee or officer of], or consultant or advisor to, the Company or any other entity the employees, officers,
directors, consultants, or advisors of which are eligible to receive option grants under the Plan (an “Eligible Participant”). 

 (c) Termination of Relationship with the Company. If the Participant ceases to be an
Eligible Participant for any reason, then, except as provided in paragraphs (d) and (e) below, the right to exercise this option shall terminate three months after such cessation (but in no event after the Final Exercise Date),
provided that this option shall be exercisable only to the extent that the Participant was entitled to exercise this option on the date of such cessation. Notwithstanding the foregoing, if the Participant, prior to the Final Exercise
Date, violates the non-competition or confidentiality provisions of any employment contract, confidentiality and nondisclosure agreement or other agreement between the Participant and the Company, the right to
exercise this option shall terminate immediately upon such violation. 
 (d) Exercise Period Upon Death or Disability. If the
Participant dies or becomes disabled (within the meaning of Section 22(e)(3) of the Code) prior to the Final Exercise Date while he or she is an Eligible Participant and the Company has not terminated such relationship for “cause” as
specified in paragraph (e) below, this option shall be exercisable, within the period of one year following the date of death or disability of the Participant, by the Participant (or in the case of death by an authorized transferee),
provided that this option shall be exercisable only to the extent that this option was exercisable by the Participant on the date of his or her death or disability, and further provided that this option shall not be exercisable after
the Final Exercise Date. 
 (e) Termination for Cause. If, prior to the Final Exercise Date, the Participant’s employment or
other relationship with the Company is terminated by the Company for Cause (as defined below), the right to exercise this option shall terminate immediately upon the effective date of such termination of employment or other relationship. If the
Participant is party to an employment, consulting or severance agreement with the Company that contains a definition of “cause” for termination of employment or other relationship, “Cause” shall have the meaning ascribed to such
term in such agreement. Otherwise, “Cause” shall mean willful misconduct by the Participant or willful failure by the Participant to perform his or her responsibilities to the Company (including, without limitation, breach by the
Participant of any provision of any employment, consulting, advisory, nondisclosure, non-competition or other similar agreement between the Participant and the Company), as determined by the Company, which
determination shall be conclusive. The Participant’s employment or other relationship shall be considered to have been terminated for “Cause” if the Company determines, within 30 days after the Participant’s resignation, that
termination for Cause was warranted. 
 4. Company Right of First Refusal. 

(a) Notice of Proposed Transfer. If the Participant proposes to sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by
operation of law or otherwise (collectively, “transfer”) any Shares acquired upon exercise of this option, then the Participant shall first give written notice of the proposed transfer (the “Transfer Notice”) to the Company. The
Transfer Notice shall name the proposed transferee and state the number of such Shares the Participant proposes to transfer (the “Offered Shares”), the price per share and all other material terms and conditions of the transfer. 

  
 -2- 

 (b) Company Right to Purchase. For 30 days following its receipt of such Transfer Notice,
the Company shall have the option to purchase all or part of the Offered Shares at the price and upon the terms set forth in the Transfer Notice. In the event the Company elects to purchase all or part of the Offered Shares, it shall give written
notice of such election to the Participant within such 30-day period. Within 10 days after his or her receipt of such notice, the Participant shall tender to the Company at its principal offices the
certificate or certificates representing the Offered Shares to be purchased by the Company, duly endorsed in blank by the Participant or with duly endorsed stock powers attached thereto, all in a form suitable for transfer of the Offered Shares to
the Company. Promptly following receipt of such certificate or certificates, the Company shall deliver or mail to the Participant a check in payment of the purchase price for such Offered Shares; provided that if the terms of payment
set forth in the Transfer Notice were other than cash against delivery, the Company may pay for the Offered Shares on the same terms and conditions as were set forth in the Transfer Notice; and provided further that any delay in making
such payment shall not invalidate the Company’s exercise of its option to purchase the Offered Shares. 
 (c) Shares Not Purchased By
Company. If the Company does not elect to acquire all of the Offered Shares, the Participant may, within the 30-day period following the expiration of the option granted to the Company under subsection
(b) above, transfer the Offered Shares which the Company has not elected to acquire to the proposed transferee, provided that such transfer shall not be on terms and conditions more favorable to the transferee than those contained
in the Transfer Notice. Notwithstanding any of the above, all Offered Shares transferred pursuant to this Section 4 shall remain subject to the right of first refusal set forth in this Section 4 and such transferee shall, as a condition to
such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Section 4. 

(d) Consequences of Non-Delivery. After the time at which the Offered Shares are required to be
delivered to the Company for transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Offered Shares or permit the Participant to exercise any of the privileges or
rights of a stockholder with respect to such Offered Shares, but shall, insofar as permitted by law, treat the Company as the owner of such Offered Shares. 

(e) Exempt Transactions. The following transactions shall be exempt from the provisions of this Section 4: 

(1) any transfer of Shares to or for the benefit of any spouse, child or grandchild of the Participant, or to a trust for their benefit; 

(2) any transfer pursuant to an effective registration statement filed by the Company under the Securities Act of 1933, as amended (the
“Securities Act”); and 
 (3) the sale of all or substantially all of the outstanding shares of capital stock of the Company
(including pursuant to a merger or consolidation); 

  
 -3- 

 provided, however, that in the case of a transfer pursuant to clause (1) above, such Shares
shall remain subject to the right of first refusal set forth in this Section 4. 
 (f) Assignment of Company Right. The Company
may assign its rights to purchase Offered Shares in any particular transaction under this Section 4 to one or more persons or entities. 

(g) Termination. The provisions of this Section 4 shall terminate upon the earlier of the following events: 

(1) the closing of the sale of shares of Common Stock in an underwritten public offering pursuant to an effective registration statement filed
by the Company under the Securities Act; or 
 (2) the sale of all or substantially all of the outstanding shares of capital stock, assets or
business of the Company, by merger, consolidation, sale of assets or otherwise (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the Company’s voting securities
immediately prior to such transaction beneficially own, directly or indirectly, more than 50% (determined on an as-converted basis) of the outstanding securities entitled to vote generally in the election of
directors of the resulting, surviving or acquiring corporation in such transaction). 
 (h) No Obligation to Recognize Invalid
Transfer. The Company shall not be required (1) to transfer on its books any of the Shares which shall have been sold or transferred in violation of any of the provisions set forth in this Section 4, or (2) to treat as owner of
such Shares or to pay dividends to any transferee to whom any such Shares shall have been so sold or transferred. 
 (i) Legends. The
certificate representing Shares shall bear a legend substantially in the following form (in addition to, or in combination with, any legend required by applicable federal and state securities laws and agreements relating to the transfer of the
Company securities): 
 “The shares represented by this certificate are subject to a right of first refusal in favor of the Company, as
provided in a certain stock option agreement with the Company.” 
 5. Agreement in Connection with Initial Public Offering. 

The Participant agrees, in connection with the initial underwritten public offering of the Common Stock pursuant to a registration statement
under the Securities Act, (i) not to (a) offer, pledge, announce the intention to sell, 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 other securities of the Company or (b) enter into any swap or other agreement that transfers, in whole or in part, any of the economic
consequences of ownership of shares of Common Stock or other securities of the Company, whether any transaction described in clause (a) or (b) is to be settled by delivery of securities, in cash or otherwise, during the period beginning on the
date of 

  
 -4- 

 
the filing of such registration statement with the Securities and Exchange Commission and ending 180 days after the date of the final prospectus relating to the offering (plus up to an additional
34 days to the extent requested by the managing underwriters for such offering in order to address Rule 2711(f) of the National Association of Securities Dealers, Inc. or any similar successor provision), and (ii) to execute any agreement
reflecting clause (i) above as may be requested by the Company or the managing underwriters at the time of such offering. The Company may impose stop-transfer instructions with respect to the shares of Common Stock or other securities subject
to the foregoing restriction until the end of the “lock-up” period. 
 6. Withholding. 

No Shares will be issued pursuant to the exercise of this option unless and until the Participant pays to the Company, or makes provision
satisfactory to the Company for payment of, any federal, state or local withholding taxes required by law to be withheld in respect of this option. 
 7.
Transfer Restrictions. 
 (a) This option may not be sold, assigned, transferred, pledged or otherwise encumbered by the Participant,
either voluntarily or by operation of law, except by will or the laws of descent and distribution, and, during the lifetime of the Participant, this option shall be exercisable only by the Participant.
 
 (b) The Participant agrees that he or she will not transfer any Shares issued pursuant to the exercise of this option unless the
transferee, as a condition to such transfer, delivers to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of Section 4 and Section 5; provided that such a written
confirmation shall not be required with respect to (1) Section 4 after such provision has terminated in accordance with Section 4(g) or (2) Section 5 after the completion of the
lock-up period in connection with the Company’s initial underwritten public offering. 
 8. Provisions of
the Plan. 
 This option is subject to the provisions of the Plan (including the provisions relating to amendments to the Plan), a copy
of which is furnished to the Participant with this option. 

  
 -5- 

 IN WITNESS WHEREOF, the Company has caused this option to be executed under its corporate seal by
its duly authorized officer. This option shall take effect as a sealed instrument. 
  

			
	RESTORBIO, INC.

 
			
		
	By:	 	  

	Name:	 	
	Title:	 	

  
 -6- 

 PARTICIPANT’S ACCEPTANCE 

The undersigned hereby accepts the foregoing option and agrees to the terms and conditions thereof. The undersigned hereby acknowledges
receipt of a copy of the Company’s 2017 Stock Incentive Plan. 
  

			
	PARTICIPANT:
	  

		
	Address:	 	  

		 	  

  
 -7- 

 EXHIBIT A 

NOTICE OF STOCK OPTION EXERCISE 

[DATE]1 

resTORbio, Inc. 
 501 Boylston Street, Suite 6102 

Boston, MA 02116 
 Attention: Treasurer 

Dear Sir or Madam: 
 I am the holder of an
Nonstatutory Stock Option granted to me under the resTORbio, Inc. (the “Company”) 2017 Stock Incentive Plan on
[                    ]2 for the purchase of
[                    ]3 shares of Common Stock of the Company at a purchase price of
$[                    ]4 per share. 

I hereby exercise my option to purchase
[                ]5 shares of Common Stock (the “Shares”), for which I have enclosed
[                ]6 in the amount of
[                ]7. Please register my stock certificate as follows: 

 

							
		 	Name(s):	  	                                      
                  8	  	
		 		  	                                      
                  	  	
				
		 	Address:	  	                                      
                  	  	
		 		  	                                      
                  	  	

 I represent, warrant and covenant as follows: 

 

	1 	Enter date of exercise. 

	2 	Enter the date of grant. 

	3 	Enter the total number of shares of Common Stock for which the option was granted. 

	4 	Enter the option exercise price per share of Common Stock. 

	5 	Enter the number of shares of Common Stock to be purchased upon exercise of all or part of the option. 

	6 	Enter “cash”, “personal check” or if permitted by the option or Plan, “stock certificates No. XXXX and XXXX”. 

	7 	Enter the dollar amount (price per share of Common Stock times the number of shares of Common Stock to be purchased), or the number of shares tendered. Fair market value of shares tendered, together with cash or check,
must cover the purchase price of the shares issued upon exercise. 

	8 	Enter name(s) to appear on stock certificate in one of the following formats: (a) your name only (i.e., John Doe); (b) your name and other name (i.e., John Doe and Jane Doe, Joint Tenants with Right to
Survivorship); or for Nonstatutory Stock Options only, (c) a child’s name, with you as custodian (i.e. Jane Doe, Custodian for Tommy Doe). Note: There may be income and/or gift tax consequences for registering shares in a child’s
name. 

  
 -8- 

 1. I am purchasing the Shares for my own account for investment only, and not with a view to, or for sale in
connection with, any distribution of the Shares in violation of the Securities Act of 1933 (the “Securities Act”), or any rule or regulation under the Securities Act. 

2. I have had such opportunity as I have deemed adequate to obtain from representatives of the Company such information as is necessary to permit me to
evaluate the merits and risks of my investment in the Company. 
 3. I have sufficient experience in business, financial and investment matters to be able to
evaluate the risks involved in the purchase of the Shares and to make an informed investment decision with respect to such purchase. 
 4. I can afford a
complete loss of the value of the Shares and am able to bear the economic risk of holding such Shares for an indefinite period. 
 5. I understand that
(i) the Shares have not been registered under the Securities Act and are “restricted securities” within the meaning of Rule 144 under the Securities Act, (ii) the Shares cannot be sold, transferred or otherwise disposed of unless
they are subsequently registered under the Securities Act or an exemption from registration is then available; (iii) in any event, the exemption from registration under Rule 144 will not be available for at least one year and even then will not
be available unless a public market then exists for the Common Stock, adequate information concerning the Company is then available to the public, and other terms and conditions of Rule 144 are complied with; and (iv) there is now no
registration statement on file with the Securities and Exchange Commission with respect to any stock of the Company and the Company has no obligation or current intention to register the Shares under the Securities Act. 

 

	
	Very truly yours,
	  

	[Name]

  
 -9- 

 RESTORBIO, INC. 

Incentive Stock Option Agreement 

Granted Under 2017 Stock Incentive Plan 

1. Grant of Option. 
 This agreement
evidences the grant by resTORbio, Inc., a Delaware corporation (the “Company”), on                  ,
20[        ] (the “Grant Date”) to [                ], an employee of the
Company (the “Participant”), of an option to purchase, in whole or in part, on the terms provided herein and in the Company’s 2017 Stock Incentive Plan (the “Plan”), a total of
[             ] shares (the “Shares”) of common stock, $0.0001 par value per share, of the Company (“Common Stock”) at
$[             ] per Share. Unless earlier terminated, this option shall expire at 5:00 p.m., Eastern time, on
[                ] (the “Final Exercise Date”). 

It is intended that the option evidenced by this agreement shall be an incentive stock option as defined in Section 422 of the Internal
Revenue Code of 1986, as amended, and any regulations promulgated thereunder (the “Code”). Except as otherwise indicated by the context, the term “Participant”, as used in this option, shall be deemed to include any person who
acquires the right to exercise this option validly under its terms. 
 2. Vesting Schedule. 

This option will become exercisable (“vest”) as to [25]% of the original number of Shares on the [first] anniversary of the
Vesting Commencement Date and as to an additional [12.5]% of the original number of Shares at the end of each successive [six-month] period following the first anniversary of the Vesting
Commencement Date until the [fourth] anniversary of the Vesting Commencement Date. The Vesting Commencement Date shall be [                ]. 

The right of exercise shall be cumulative so that to the extent the option is not exercised in any period to the maximum extent permissible it
shall continue to be exercisable, in whole or in part, with respect to all Shares for which it is vested until the earlier of the Final Exercise Date or the termination of this option under Section 3 hereof or the Plan. 

3. Exercise of Option. 
 (a) Form of
Exercise. Each election to exercise this option shall be accompanied by a completed Notice of Stock Option Exercise in the form attached hereto as Exhibit A, signed by the Participant, and received by the Company at its principal office,
accompanied by this Agreement, and payment in full in the manner provided in the Plan. The Participant may purchase less than the number of shares covered hereby, provided that no partial exercise of this option may be for any fractional share. 

(b) Continuous Relationship with the Company Required. Except as otherwise provided in this Section 3, this option may not be
exercised unless the Participant, at the time he or she exercises this option, is, and has been at all times since the Grant Date, an employee or officer of, or consultant or advisor to, the Company or any parent or subsidiary of the Company as
defined in Section 424(e) or (f) of the Code (an “Eligible Participant”). 

 (c) Termination of Relationship with the Company. If the Participant ceases to be an
Eligible Participant for any reason, then, except as provided in paragraphs (d) and (e) below, the right to exercise this option shall terminate three months after such cessation (but in no event after the Final Exercise Date),
provided that this option shall be exercisable only to the extent that the Participant was entitled to exercise this option on the date of such cessation. Notwithstanding the foregoing, if the Participant, prior to the Final Exercise
Date, violates the non-competition or confidentiality provisions of any employment contract, confidentiality and nondisclosure agreement or other agreement between the Participant and the Company, the right to
exercise this option shall terminate immediately upon such violation. 
 (d) Exercise Period Upon Death or Disability. If the
Participant dies or becomes disabled (within the meaning of Section 22(e)(3) of the Code) prior to the Final Exercise Date while he or she is an Eligible Participant and the Company has not terminated such relationship for “cause” as
specified in paragraph (e) below, this option shall be exercisable, within the period of one year following the date of death or disability of the Participant, by the Participant (or in the case of death by an authorized transferee),
provided that this option shall be exercisable only to the extent that this option was exercisable by the Participant on the date of his or her death or disability, and further provided that this option shall not be exercisable after
the Final Exercise Date. 
 (e) Termination for Cause. If, prior to the Final Exercise Date, the Participant’s employment is
terminated by the Company for Cause (as defined below), the right to exercise this option shall terminate immediately upon the effective date of such termination of employment. If the Participant is party to an employment or severance agreement with
the Company that contains a definition of “cause” for termination of employment, “Cause” shall have the meaning ascribed to such term in such agreement. Otherwise, “Cause” shall mean willful misconduct by the
Participant or willful failure by the Participant to perform his or her responsibilities to the Company (including, without limitation, breach by the Participant of any provision of any employment, consulting, advisory, nondisclosure, non-competition or other similar agreement between the Participant and the Company), as determined by the Company, which determination shall be conclusive. The Participant’s employment shall be considered to
have been terminated for Cause if the Company determines, within 30 days after the Participant’s resignation, that termination for Cause was warranted. 

4. Company Right of First Refusal. 
 (a)
Notice of Proposed Transfer. If the Participant proposes to sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of law or otherwise (collectively, “transfer”) any Shares acquired upon exercise of this
option, then the Participant shall first give written notice of the proposed transfer (the “Transfer Notice”) to the Company. The Transfer Notice shall name the proposed transferee and state the number of such Shares the Participant
proposes to transfer (the “Offered Shares”), the price per share and all other material terms and conditions of the transfer. 

  
 -2- 

 (b) Company Right to Purchase. For 30 days following its receipt of such Transfer Notice,
the Company shall have the option to purchase all or part of the Offered Shares at the price and upon the terms set forth in the Transfer Notice. In the event the Company elects to purchase all or part of the Offered Shares, it shall give written
notice of such election to the Participant within such 30-day period. Within 10 days after his or her receipt of such notice, the Participant shall tender to the Company at its principal offices the
certificate or certificates representing the Offered Shares to be purchased by the Company, duly endorsed in blank by the Participant or with duly endorsed stock powers attached thereto, all in a form suitable for transfer of the Offered Shares to
the Company. Promptly following receipt of such certificate or certificates, the Company shall deliver or mail to the Participant a check in payment of the purchase price for such Offered Shares; provided that if the terms of payment
set forth in the Transfer Notice were other than cash against delivery, the Company may pay for the Offered Shares on the same terms and conditions as were set forth in the Transfer Notice; and provided further that any delay in making
such payment shall not invalidate the Company’s exercise of its option to purchase the Offered Shares. 
 (c) Shares Not Purchased By
Company. If the Company does not elect to acquire all of the Offered Shares, the Participant may, within the 30-day period following the expiration of the option granted to the Company under subsection
(b) above, transfer the Offered Shares which the Company has not elected to acquire to the proposed transferee, provided that such transfer shall not be on terms and conditions more favorable to the transferee than those contained
in the Transfer Notice. Notwithstanding any of the above, all Offered Shares transferred pursuant to this Section 4 shall remain subject to the right of first refusal set forth in this Section 4 and such transferee shall, as a condition to
such transfer, deliver to the Company a written instrument confirming that such transferee shall be bound by all of the terms and conditions of this Section 4. 

(d) Consequences of Non-Delivery. After the time at which the Offered Shares are required to be
delivered to the Company for transfer to the Company pursuant to subsection (b) above, the Company shall not pay any dividend to the Participant on account of such Offered Shares or permit the Participant to exercise any of the privileges or
rights of a stockholder with respect to such Offered Shares, but shall, insofar as permitted by law, treat the Company as the owner of such Offered Shares. 

(e) Exempt Transactions. The following transactions shall be exempt from the provisions of this Section 4: 

(1) any transfer of Shares to or for the benefit of any spouse, child or grandchild of the Participant, or to a trust for their benefit; 

(2) any transfer pursuant to an effective registration statement filed by the Company under the Securities Act of 1933, as amended (the
“Securities Act”); and 
 (3) the sale of all or substantially all of the outstanding shares of capital stock of the Company
(including pursuant to a merger or consolidation); 

  
 -3- 

 provided, however, that in the case of a transfer pursuant to clause (1) above, such Shares
shall remain subject to the right of first refusal set forth in this Section 4. 
 (f) Assignment of Company Right. The Company
may assign its rights to purchase Offered Shares in any particular transaction under this Section 4 to one or more persons or entities. 

(g) Termination. The provisions of this Section 4 shall terminate upon the earlier of the following events: 

(1) the closing of the sale of shares of Common Stock in an underwritten public offering pursuant to an effective registration statement filed
by the Company under the Securities Act; or 
 (2) the sale of all or substantially all of the outstanding shares of capital stock, assets or
business of the Company, by merger, consolidation, sale of assets or otherwise (other than a merger or consolidation in which all or substantially all of the individuals and entities who were beneficial owners of the Company’s voting securities
immediately prior to such transaction beneficially own, directly or indirectly, more than 50% (determined on an as-converted basis) of the outstanding securities entitled to vote generally in the election of
directors of the resulting, surviving or acquiring corporation in such transaction). 
 (h) No Obligation to Recognize Invalid
Transfer. The Company shall not be required (1) to transfer on its books any of the Shares which shall have been sold or transferred in violation of any of the provisions set forth in this Section 4, or (2) to treat as owner of
such Shares or to pay dividends to any transferee to whom any such Shares shall have been so sold or transferred. 
 (i) Legends. The
certificate representing Shares shall bear a legend substantially in the following form (in addition to, or in combination with, any legend required by applicable federal and state securities laws and agreements relating to the transfer of the
Company securities): 
 “The shares represented by this certificate are subject to a right of first refusal in favor of the Company, as
provided in a certain stock option agreement with the Company.” 
 5. Agreement in Connection with Initial Public Offering. 

The Participant agrees, in connection with the initial underwritten public offering of the Common Stock pursuant to a registration statement under the
Securities Act, (i) not to (a) offer, pledge, announce the intention to sell, 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 other securities of the Company or (b) enter into any swap or other agreement that transfers, in whole or in part, any of the economic consequences of
ownership of shares of Common Stock or other securities of the Company, whether any transaction described in clause (a) or (b) is to be settled by delivery of securities, in cash or otherwise, during the period beginning on the date of

  
 -4- 

 
the filing of such registration statement with the Securities and Exchange Commission and ending 180 days after the date of the final prospectus relating to the offering (plus up to an additional
34 days to the extent requested by the managing underwriters for such offering in order to address Rule 2711(f) of the National Association of Securities Dealers, Inc. or any similar successor provision), and (ii) to execute any agreement
reflecting clause (i) above as may be requested by the Company or the managing underwriters at the time of such offering. The Company may impose stop-transfer instructions with respect to the shares of Common Stock or other securities subject
to the foregoing restriction until the end of the “lock-up” period. 
 6. Tax Matters. 

(a) Withholding. No Shares will be issued pursuant to the exercise of this option unless and until the Participant pays to the Company,
or makes provision satisfactory to the Company for payment of, any federal, state or local withholding taxes required by law to be withheld in respect of this option. 

(b) Disqualifying Disposition. If the Participant disposes of Shares acquired upon exercise of this option within two years from the
Grant Date or one year after such Shares were acquired pursuant to exercise of this option, the Participant shall notify the Company in writing of such disposition. 

7. Transfer Restrictions. 
 (a) This
option may not be sold, assigned, transferred, pledged or otherwise encumbered by the Participant, either voluntarily or by operation of law, except by will or the laws of descent and distribution, and, during the lifetime of the Participant, this
option shall be exercisable only by the Participant.  
 (b) The Participant agrees that
he or she will not transfer any Shares issued pursuant to the exercise of this option unless the transferee, as a condition to such transfer, delivers to the Company a written instrument confirming that such transferee shall be bound by all of the
terms and conditions of Section 4 and Section 5; provided that such a written confirmation shall not be required with respect to (1) Section 4 after such provision has terminated in accordance with Section 4(g) or
(2) Section 5 after the completion of the lock-up period in connection with the Company’s initial underwritten public offering. 

8. Provisions of the Plan. 
 This option
is subject to the provisions of the Plan (including the provisions relating to amendments to the Plan), a copy of which is furnished to the Participant with this option. 

  
 -5- 

 IN WITNESS WHEREOF, the Company has caused this option to be executed under its corporate seal by
its duly authorized officer. This option shall take effect as a sealed instrument. 
  

			
	RESTORBIO, INC.

 
			
		
	By:	 	  

		 	Name:
		 	Title:

  
 -6- 

 PARTICIPANT’S ACCEPTANCE 

The undersigned hereby accepts the foregoing option and agrees to the terms and conditions thereof. The undersigned hereby acknowledges
receipt of a copy of the Company’s 2017 Stock Incentive Plan. 
  

			
	PARTICIPANT:
	  

	Address:	 	  

		 	  

  
 -7- 

 EXHIBIT A 

NOTICE OF STOCK OPTION EXERCISE 

[DATE]1 

resTORbio, Inc. 
 501 Boylston Street, Suite 6102 

Boston, MA 02116 
 Attention: Treasurer 

Dear Sir or Madam: 
 I am the holder of an
Incentive Stock Option granted to me under the resTORbio, Inc. (the “Company”) 2017 Stock Incentive Plan on [                ]2 for the purchase of
[                    ]3 shares of Common Stock of the Company at a purchase price of
$[                    ]4 per share. 

I hereby exercise my option to purchase
[                    ]5 shares of Common Stock (the “Shares”), for which
I have enclosed [                ]6 in the amount of
[                ]7. Please register my stock certificate as follows: 

 

							
		 	Name(s):	  	                                      
                  8	  	
		 		  	                                      
                  	  	
				
		 	Address:	  	                                      
                  	  	
		 		  	                                      
                  	  	

 I represent, warrant and covenant as follows: 

 

	1 	Enter date of exercise. 

	2 	Enter the date of grant. 

	3 	Enter the total number of shares of Common Stock for which the option was granted. 

	4 	Enter the option exercise price per share of Common Stock. 

	5 	Enter the number of shares of Common Stock to be purchased upon exercise of all or part of the option. 

	6 	Enter “cash”, “personal check” or if permitted by the option or Plan, “stock certificates No. XXXX and XXXX”. 

	7 	Enter the dollar amount (price per share of Common Stock times the number of shares of Common Stock to be purchased), or the number of shares tendered. Fair market value of shares tendered, together with cash or check,
must cover the purchase price of the shares issued upon exercise. 

	8 	Enter name(s) to appear on stock certificate in one of the following formats: (a) your name only (i.e., John Doe); (b) your name and other name (i.e., John Doe and Jane Doe, Joint Tenants with Right to
Survivorship); or for Nonstatutory Stock Options only, (c) a child’s name, with you as custodian (i.e. Jane Doe, Custodian for Tommy Doe). Note: There may be income and/or gift tax consequences for registering shares in a child’s
name. 

  
 -8- 

 1. I am purchasing the Shares for my own account for investment only, and not with a view to, or for sale in
connection with, any distribution of the Shares in violation of the Securities Act of 1933 (the “Securities Act”), or any rule or regulation under the Securities Act. 

2. I have had such opportunity as I have deemed adequate to obtain from representatives of the Company such information as is necessary to permit me to
evaluate the merits and risks of my investment in the Company. 
 3. I have sufficient experience in business, financial and investment matters to be able to
evaluate the risks involved in the purchase of the Shares and to make an informed investment decision with respect to such purchase. 
 4. I can afford a
complete loss of the value of the Shares and am able to bear the economic risk of holding such Shares for an indefinite period. 
 5. I understand that
(i) the Shares have not been registered under the Securities Act and are “restricted securities” within the meaning of Rule 144 under the Securities Act, (ii) the Shares cannot be sold, transferred or otherwise disposed of unless
they are subsequently registered under the Securities Act or an exemption from registration is then available; (iii) in any event, the exemption from registration under Rule 144 will not be available for at least one year and even then will not
be available unless a public market then exists for the Common Stock, adequate information concerning the Company is then available to the public, and other terms and conditions of Rule 144 are complied with; and (iv) there is now no
registration statement on file with the Securities and Exchange Commission with respect to any stock of the Company and the Company has no obligation or current intention to register the Shares under the Securities Act. 

 

	
	Very truly yours,
	
	  

	[Name]

  
 -9-

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