Document:

EX-10.2

 Exhibit 10.2 

INOZYME PHARMA, LLC 

REGISTRATION RIGHTS AGREEMENT 

THIS REGISTRATION RIGHTS AGREEMENT, dated as of June 1, 2016 (this “Agreement”), by and among Inozyme Pharma, LLC, a
Delaware limited liability company (the “Company”), and holders of the Company’s Class 1 Stock (the “Class 1 Stock”), listed on Exhibit A (together with certain other persons who become parties as provided
herein, the “Holders”). 
 W I T N E S S E T H: 

WHEREAS, the Company and each Holder who initially is a party to this Agreement are parties to a Restricted Stock Agreement or
Subscription Agreement of even date herewith or dated subsequent hereto (each, a “Subscription Agreement”); 
 WHEREAS, the
Company and the initial Holder(s) are executing and delivering this Agreement as a material inducement to such Holder(s) to subscribe for shares of Class 1 Stock pursuant to the Subscription Agreement(s); and 

WHEREAS, from time to time after the date of this Agreement one or more other Holders who become parties to Subscription Agreements may
also become parties to this Agreement; 
 NOW, THEREFORE, in consideration of the premises and mutual covenants contained herein and
other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows: 

1.    Definitions. 

(a)    As used in this Agreement, the terms “Agreement,” “Class 1 Stock,” “Company,”
“Holders” and “Subscription Agreement” shall have the respective meanings assigned to such terms in the introductory paragraphs of this Agreement. 

(b)    All the agreements or instruments herein defined shall mean such agreements or instruments as the same may from
time to time be supplemented or amended or the terms thereof waived or modified to the extent permitted by, and in accordance with, the terms thereof and of this Agreement. 

(c)    The following terms shall have the following meanings (such meanings to be equally applicable to both the singular
and plural forms of the terms defined): 
 “Affiliate” shall mean, with respect to a party hereto (or such party’s successors
and assigns), any person or entity that directly or indirectly, through one or more intermediaries, controls, is controlled by or is under common control with such person or entity (or such person’s or entity’s successors and assigns). For
purposes of this definition, a person or entity shall be deemed to be “controlled by” another person or entity if the other possesses, directly or indirectly, power either (i) to vote fifty percent (50%) or more of the securities
having ordinary voting power 

 
for the election of directors of such person or entity, or (ii) to direct or cause the direction of the management and policies of such person or entity whether by contract or otherwise,
provided, however, that for purposes of clarity, in addition to the foregoing, with respect to any venture capital investor, “Affiliate” shall include any partnership, limited liability company or fund sharing a common management
company or similar entity. 
 “Class 1 Stock” includes the Class 1 Stock of the Company as authorized on the date
hereof, and any other securities into which or for which the Class 1 Stock may be converted or exchanged pursuant to a plan of recapitalization, reorganization, merger, sale of assets or otherwise and any stock (other than Class 1 Stock)
and other securities of the Company or any other Person which any holder of Class 1 Stock at any time shall be entitled to receive, or shall have received, on the exercise of conversion or exchange rights of the Class 1 Stock or any such
other securities, in lieu of or in addition to Class 1 Stock. 
 “Excluded Registration Statement” means a Registration
Statement under the 1933 Act on Form S-3, S-4 or S-8 or similar or successor registration statement forms of the SEC under the
1933 Act. 
 “Form S-3” means a Registration Statement on Form S-3 under the 1933 Act, as such form is in effect on the date hereof or any registration form under the 1933 Act subsequently adopted by the SEC which permits inclusion or incorporation of substantial information by
reference to other documents filed by the Company with the SEC. 
 “Holder” means any person owning or having the right to acquire
Registrable Securities or any assignee thereof in accordance with Section 2(k) hereof. 
 “Initiating Holders” shall have the
meaning provided in Section 2(a)(1). 
 “IPO” means the first firm commitment underwritten sale of equity securities for the
account of the Company pursuant to a registration statement filed by the Company under the 1933 Act (other than a registration of securities in a transaction to which Rule 145 under the 1933 Act applies or with respect to an employee benefit plan).

 “Material Adverse Effect” means a material adverse effect on (1) the business, assets, liabilities, operations, results of
operations, intellectual property, management, condition (financial or other) or prospects of the Company; (2) the validity or enforceability of any transaction document or the ability of the Company to perform its obligations hereunder or
thereunder or (3) the rights and remedies of the Holders under the transaction documents or applicable law. 
 “1934 Act”
means the Securities Exchange Act of 1934, as amended. 
 “1933 Act” means the Securities Act of 1933, as amended. 

“register”, “registered,” and “registration” refer to a registration effected by preparing and filing a
registration statement or similar document in compliance with the 1933 Act, and the declaration or ordering of effectiveness of such registration statement or document; 

  
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 “Registrable Securities” means (1) the Class 1 Stock issuable or issued
to the Holders pursuant to the Subscription Agreements, (2) any shares of Class 1 Stock issued to a Holder after the date of this Agreement or issued or issuable to a Holder upon conversion or exercise of a Subject Stock Equivalent issued
to a Holder after the date of this Agreement and (3) any Class 1 Stock issued as (or issuable upon the conversion or exercise of any Subject Stock Equivalent which is issued as) a dividend or other distribution with respect to, or in
exchange for or in replacement of, such Class 1 Stock, or any such Subject Stock Equivalent referred to in the immediately preceding clause (1) or (2), excluding in all cases, however, (i) any Registrable Securities sold by a Holder
in a transaction in which such Holder’s rights under Section 2 are not assigned, (ii) any Registrable Securities sold to or through a broker or dealer or underwriter in a public distribution or a public securities transaction and
(iii) Registrable Securities which can be sold under Rule 144(k) under the 1933 Act; provided that the Registrable Securities are then listed on a national securities exchange or on the New York Stock Exchange, Inc., the American Stock
Exchange, Inc. or the Nasdaq Stock Market. 
 “SEC” means the U.S. Securities and Exchange Commission. 

“Subject Stock” means all stock of the Company representing membership interests in the Company entitled to share in the residual
value of the Company in connection with a dissolution and liquidation of the Company, including, without limitation, Class 1 Stock, Class 2 Stock and Class 3 Stock, and any securities derivates relating thereto, including any Subject
Stock Equivalents. 
 “Subject Stock Equivalent” means any warrant, option, subscription or purchase right with respect to shares
of Subject Stock, any security convertible into, exchangeable for, or otherwise entitling the holder thereof to acquire shares of Subject Stock and any warrant, option, subscription or purchase right with respect to any such convertible,
exchangeable or other security. 
 “S-3 Initiating Holders” shall have the meaning
provided in Section 2(c). 
 “Violation” shall have the meaning provided in section 2(i)(1) 

2.    Registration Rights 

(a)    Request for Registration. 

(1)    If the Company shall receive at any time after the date that is one year following the date of the closing of the
IPO a request from the Holders of at least 30% of the Registrable Securities that the Company file a registration statement under the 1933 Act, then the Company shall, within ten (10) days after the receipt thereof, give notice of such request
to all Holders and shall, subject to the limitations of Section 2(a)(2), use its best efforts to effect as soon as practicable, and in any event within ninety (90) days after the receipt of such request from the Holders initiating a
request under this Section 2(a) (the “Initiating Holders”), the registration under the 1933 Act of all Registrable Securities which, within twenty (20) days after the Company gives such notice, the Holders request to be so

  
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registered; provided, however, that the Company shall not be obligated to take any action to effect any such registration, qualification or compliance pursuant to this
Section 2(a)(1): 
 (A)    While another registration statement (other than Form S-3 or an Excluded Registration Statement) of the Company has been filed with the SEC and is not yet effective or on or within one hundred eighty (180) days after the effective date of another registration
statement (other than Form S-3 or an Excluded Registration Statement) filed by the Company with the SEC; 

(B)    While another registration statement (other than Form S-3 or
an Excluded Registration Statement) of the Company has been requested or demanded to register shares of Class 1 Stock issued or issuable upon conversion of shares of the Company’s Preferred Stock of a class that ranks senior to the
Class 1 Stock as to distribution of profits and distribution of assets upon dissolution of the Company or while any such registration statement has been filed with the SEC and is not yet effective or on or within one hundred eighty
(180) days after the effective date of any such registration statement (other than on Form S-4 or S-8) filed by the Company with the SEC. 

(C)    After the Holders have requested two such registrations pursuant to this Section 2(a)(1) and
such registrations have been declared or ordered effective by the SEC, so long as the Company shall have complied with its obligations in this Agreement relating to such registrations; provided however, that if any Holder is unable to include
in such registration any Registrable Securities that such Holder requests be included in any such registration, the Holders shall be entitled to one additional registration for each such registration from which any Registrable Securities are so
excluded; or 
 (D)    If the Company shall furnish to the Holders a certificate signed by the Chairman
of the Board or the Chief Executive Officer of the Company stating that in the good faith judgment of the Board of Managers of the Company, as evidenced by a duly adopted resolution of the Board of Managers of the Company, it would be seriously
detrimental to the Company or its members for a registration statement to be filed at such time, then the Company’s obligation to use its best efforts to register, qualify or comply under this Section 2(a)(1) shall be deferred for a period
(as specified in such resolution) not to exceed ninety (90) days from the date of receipt of such written request from the Initiating Holders; provided, however, that the Company may not utilize this right to delay fulfillment of a
request more than once in any twelve-month period. 
 (2)    If the Initiating Holders intend to distribute the
Registrable Securities covered by their request by means of an underwriting, they shall so inform the Company as a part of their request made pursuant to this Section 2(a) and the Company shall include such information in the written notice
referred to in Section 2(a)(1). 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 such underwriting (unless otherwise mutually agreed by a majority in interest of the Initiating Holders) to the extent provided herein. All Holders proposing to distribute their securities through such
underwriting shall (together with the Company, as provided in Section 2(d)(6)) enter into an underwriting agreement in usual and customary form with the underwriter or underwriters selected for such underwriting by a majority in interest of the
Initiating Holders and approved by the Company. Notwithstanding any other provision of this Section 2(a), if the underwriter advises the Company and the Holders electing to participate in such registration in writing that marketing

  
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factors require a limitation of the number of shares to be underwritten, then the Company shall promptly so notify all Holders of Registrable Securities which would otherwise be included in such
underwritten offering pursuant hereto, and the number of Registrable Securities that may be included in such underwritten offering shall be allocated as follows: 

(i)    first, among persons who have the right to include shares in such registration statement pursuant to
an agreement other than this Agreement, to the extent such other agreement affords such persons priority over the Holders to include their shares in such registration statement, and 

(ii)    thereafter among the Holders who have elected to participate in such underwritten offering, in such
proportion (as nearly as practicable) as the number of Registrable Securities held by each Holder bears to the aggregate amount of Registrable Securities held by all such Holders, until such Holders have included in the underwriting all Registrable
Securities that such Holders have requested to be included in such registration, and 

(iii)    thereafter, among all other persons who have the right to include shares in such registration, in
such relative priorities as established by the agreement(s) under which such rights arise. 
 Without the consent of a majority in interest of the
Initiating Holders, except as permitted by clause (i) of the immediately preceding sentence, no securities other than Registrable Securities shall be covered by such registration if the inclusion of such other securities would result in a
reduction of the number of Registrable Securities covered by such registration or included in any underwriting or if, in the opinion of the managing underwriter, the inclusion of such other securities would adversely affect the marketing of such
offering. 
 (b)    Company Registration. If the Company at any time after the closing of
the IPO proposes to register (including for this purpose a registration effected by the Company for stockholders other than the Holders) any of its stock or other securities under the 1933 Act in connection with the public offering of such
securities solely for cash (other than an Excluded Registration Statement), the Company shall, at least ten (10) days prior to the filing of any registration statement under the 1933 Act relating thereto, promptly give each Holder notice of
such registration, unless by the terms of any agreement between the Company and any holders of securities to which such registration relates the Holders are not permitted to include any Registrable Securities in such registration. Such notice shall
be given by mail and, concurrent with the deposit of such notice in the mail, by email to the Holders who have furnished email addresses to the Company. Upon the written request of a Holder given within ten (10) days after the Company gives
such notice to such Holder (which request shall specify the number of Registrable Securities to be included in such registration statement), the Company shall, subject to the provisions of Section 2(g), cause to be registered under the 1933 Act
all of the Registrable Securities that such Holder has requested to be registered. 
 (c)    Form S-3 Registration. In case the Company shall receive from the Holders of at least 30% of the Registrable Securities (the “S-3 Initiating Holders”) a request
that the Company effect a registration on Form S-3 and any related qualification or compliance with 

  
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respect to all or a part of the Registrable Securities owned by the S-3 Initiating Holder or S-3 Initiating
Holders, the Company will: 
 (1)    promptly give notice of the proposed registration, and any related qualification or
compliance, to all other Holders; and 
 (2)    as soon as practicable, effect such registration and all such
qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Initiating Holder’s or Initiating Holders’ Registrable Securities as are specified in such
request, together with all or such portion of the Registrable Securities of any other Holder or Holders joining in such request as are specified in a request given within ten (10) days after receipt of such notice from the Company; provided,
however, that the Company shall not be obligated to effect any such registration, qualification or compliance, pursuant to this Section 2(c): 

(1)    if Form S-3 is unavailable for such offering by the Holders;

 (2)    if the Holders, together with the holders of any other securities of the Company entitled to
inclusion in such registration, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public of less than $1,000,000, unless the Registrable Securities to be so registered are all the Registrable
Securities held by the S-3 Initiating Holders; 
 (3)    if the
Company shall furnish to the Holders a certificate signed by the Chairman of the Board or the Chief Executive Officer of the Company stating that in the good faith judgment of the Board of Managers of the Company, as evidenced by a duly adopted
resolution of the Board of Managers of the Company, it would be seriously detrimental to the Company and its members for such registration on Form S-3 to be effected at such time, in which event the Company
shall have the right to defer the filing of the Form S-3 for a period of not more than ninety (90) days after receipt of the request of the S-3 Initiating Holder or
S-3 Initiating Holders under this Section 2(c); provided, however, that the Company shall not utilize this right more than once in any twelve-month period; or 

(4)    in any particular jurisdiction in which the Company would be required to qualify to do business,
subject itself to taxation measured by its income or revenues if the Company is not otherwise subject to such taxation in such jurisdiction or to execute a general consent to service of process in any such case in effecting such registration,
qualification or compliance. 
 (3)    Subject to the foregoing, the Company shall file a registration statement
covering the applicable Registrable Securities and other securities so requested to be registered as soon as practicable after receipt of the request or requests of the S-3 Initiating Holders. All expenses
incurred by the Company in connection with a registration requested pursuant to Section 2(c), including (without limitation) all registration, filing, qualification, printer’s and accounting fees and reasonable fees and disbursements of a
single counsel for all Holders, shall be borne by the Company. Registrations effected pursuant to this Section 2(c) shall not be counted as demands for registration or registrations effected pursuant to Sections 2(a) or 2(b), respectively. 

  
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 (d)    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: 

(1)    Prepare and file with the SEC a registration statement with respect to such Registrable Securities on the
appropriate form and use its best efforts to cause such registration statement to become effective on the earliest practicable date, and keep such registration statement effective for up to 180 days during which the applicable prospectus is
available for use by the Holders whose Registrable Securities are included in such registration (or such shorter period of time, if an underwritten offering, as the underwriters need to complete the distribution of the registered offering, or until
the Holders whose Registrable Securities are included in a particular registration have disposed of their Registrable Securities in such registration or such securities shall cease to be Registrable Securities by reason of clause (iii) of the
definition of the term “Registrable Securities” in the case of a “shelf” registration on Form S-3 or any similar or successor “short-form” registration statement); provided,
however, that the number of days that a registration statement shall be kept effective under this Section 2(d)(1) shall be increased for each day the effectiveness of such registration statement was suspended or halted, if at all. 

(2)    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 provisions of the 1933 Act with respect to the disposition of all securities covered by such registration statement. 

(3)    Furnish to each Holder a copy of all documents filed with the SEC and all correspondence from or to the staff of
the SEC in connection with such registration. 
 (4)    Furnish to the Holders such numbers of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the 1933 Act, and such other documents as they may reasonably request in order to facilitate the disposition of Registrable Securities owned by them. 

(5)    Use its best 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 Holders, provided that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business, to subject
itself to taxation based on income, if not otherwise so subject in such jurisdiction, or to file a general consent to service of process in any such state or jurisdiction. 

(6)    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 underwriters of such offering and arrange for the Company’s independent public accountants to furnish such “comfort” and other letters in customary form for underwritten offerings and
as otherwise required by such underwriting agreement. 

  
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 (7)    Notify each Holder of Registrable Securities covered by such
registration statement at any time when a prospectus relating thereto is required to be delivered under the 1933 Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing and use its best efforts to
correct such misstatement or omission as soon as practicable. 
 (8)    Furnish, at the request of any Holder requesting
registration of Registrable Securities pursuant to this Section 2, on the date that such Registrable Securities are delivered to the underwriters for sale in connection with a registration pursuant to this Section 2, if such securities are
being sold through underwriters, or, if such securities are not being sold through underwriters, on the date that the registration statement with respect to such securities becomes effective, opinions, dated such date, of counsel representing the
Company in connection with such registration, in form, scope and substance as is customarily given in such a public offering, addressed to the underwriters, if any, and to the Holders requesting registration of Registrable Securities. 

(9)    Cause all such Registrable Securities registered pursuant hereto to be listed on each securities exchange on which
similar securities issued by the Company are then listed. 
 (10)    Provide a transfer agent and registrar for all
Registrable Securities registered pursuant hereunder and a CUSIP number for all such Registrable Securities, in each case not later than the effective date of such registration. 

(11)    Refrain from bidding for or purchasing any Class 1 Stock or any right to purchase Class 1 Stock or
attempting to induce any Person to purchase any such security or right if such bid, purchase or attempt would in any way limit the right of the Holders to sell Registrable Securities under such registration statement by reason of the limitations set
forth in Regulation M under the 1934 Act. 
 (e)    Obligations of the Holders. (1) 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 shall be required in order to comply with any applicable law or regulation in connection with the registration of such
Holder’s Registrable Securities or any qualification or compliance with respect to such Holder’s Registrable Securities and referred to in this Agreement. 

(2)    The Holders hereby acknowledge that there may occasionally be times when the Company must suspend the use of a
prospectus forming a part of any registration statement filed pursuant to this Agreement until such time as an amendment to such registration statement has been filed by the Company and declared effective by the SEC or until the Company has amended
or supplemented such prospectus. Each Holder hereby covenants that it will not sell any securities pursuant to any such prospectus during the period commencing at the time at which the Company gives such Holder and any underwriters notice of the
suspension of the use of any 

  
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such prospectus and ending at the time the Company gives such Holder and any underwriters notice that the Holders may thereafter effect sales pursuant to any such prospectus. Notwithstanding
anything herein to the contrary, the Company shall not suspend use of the registration statement by the Holders unless in the good faith determination of the Company such suspension is required by the federal securities laws, including, without
limitation, the rules and regulations promulgated thereunder; provided, however, that (i) except as otherwise provided by clause (ii) below, if such suspension is required by the need for an amendment or supplement to the
registration statement or the prospectus forming a part thereof, the Company shall promptly file such required amendments or supplements as shall be necessary for the disposition of the Registrable Securities to recommence and (ii) if the Board
of Managers has determined in good faith that offers and sales pursuant to the prospectus forming part of the registration statement should not be made by reason of the presence of material undisclosed circumstances or developments with respect to
which the disclosure that would be required in the registration statement would be premature or would have a Material Adverse Effect, the Company may suspend the use of the prospectus and defer the filing of any required amendment or supplement for
the minimum period of time necessary to avoid such Material Adverse Effect; provided, further, that in the case of clause (ii) above, the Company shall not be entitled to exercise its right to block such sales or suspend use of such
prospectus more than one time (not to exceed thirty (30) days) in any twelve-month period. 
 (3)    Each Holder
agrees that any sale by such Holder of Registrable Securities pursuant to a registration statement covering Registrable Securities shall be sold in a manner described in the plan of distribution set forth therein and, unless a deemed delivery method
is available under the 1933 Act (A) if such sale is made through a broker, the Holder shall instruct such broker to deliver the prospectus to the purchaser or purchasers (or the broker or brokers therefor) in connection with such sale, shall
supply copies of the prospectus to such broker or brokers and shall instruct such broker or brokers to deliver such prospectus to the purchaser in such sale or such purchaser’s broker, (B) if such sale is made in a transaction directly
with a purchaser and not through the facilities of any securities exchange or market, the Holder shall deliver, or cause to be delivered, the prospectus to such purchaser; and (C) if such sale is made by any means other than those described in
the immediately preceding clauses (A) and (B), the Holder shall otherwise use its best efforts to comply with the prospectus delivery requirements of the 1933 Act applicable to such sale. 

(4)    Each Holder agrees that it will promptly notify the Company of any material change in the information set forth in
the registration statement regarding such Holder or its plan of distribution; each Holder agrees (a) to notify the Company if such Holder enters into any material agreement with a broker or a dealer for the sale of Registrable Securities
through a block trade, special offering, exchange distribution or a purchase by a broker or dealer and (b) in connection with such agreement, to provide to the Company in writing the information necessary to prepare any supplemental prospectus
pursuant to Rule 424(c) under the 1933 Act which is required with respect to such transaction. 
 (5)    Each Holder
shall not take any action with respect to any distribution deemed to be made pursuant to the registration statement covering such Holder’s Registrable Securities which action would constitute a violation of Regulation M under the 1934 Act or
any other applicable rule, regulation or law. 

  
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 (6)    At the end of the period during which the Company is obligated to
keep a registration statement current and effective as provided in this Agreement, the Holders of Registrable Securities included in such registration statement shall discontinue sales of Registrable Securities pursuant to such registration
statement upon receipt of notice from the Company of its intention to remove from registration the Registrable Securities covered by such registration statement that remain unsold, and each such Holder shall notify the Company of the number of its
Registrable Securities which remain unsold immediately after receipt of such notice from the Company. 

(f)    Expenses of Registration. All expenses (other than underwriting discounts and
commissions payable with respect to Registrable Securities sold in an offering) incurred by the Company in connection with registrations, filings or qualifications pursuant to Sections 2(a), 2(b) and 2(c) including (without limitation) all
registration, filing and qualification fees, printers’ and accounting fees (but not including any fees and disbursements of any counsel to any Holders) shall be borne by the Company; provided, however, that the Company shall not be
required to pay for any expenses of any registration proceeding begun pursuant to Section 2(a) 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 participating Holders shall bear such expenses), unless (a) the withdrawal is based upon material adverse information concerning the Company of which such Holders were unaware at the time of such request or any material
misstatement or omission in any registration statement filed by the Company with the SEC in connection with such offering or (b) the Holders of a majority of the Registrable Securities being registered agree to forfeit the right to a demand
registration pursuant to Section 2(a), in which event such right shall be forfeited by all Holders). If the Holders are required by this Agreement to pay all or any part of such registration expenses, such expenses shall be borne by the holders
of securities (including Registrable Securities) requesting such registration or inclusion therein in proportion to the number of securities (including Registrable Securities) for which registration was requested. If the Company is required to pay
such registration expenses of a withdrawn offering pursuant to clause (a) above, then the Holders shall not forfeit their rights pursuant to Section 2(a) to a demand registration. 

(g)    Underwriting Requirements. In connection with any offering involving an underwriting of
shares being issued by the Company, the Company shall not be required under Section 2(b) to include a particular Holder’s securities in such underwriting unless such Holder accepts the terms of the underwriting as agreed upon between the
Company and the underwriters selected by it and as are consistent with this Agreement; provided, however, that a Holder shall not be required to make any representations or warranties other than with respect to itself and its Registrable
Securities. If the total amount of securities, including Registrable Securities, requested by holders of the Company’s securities to be included in such offering exceeds the amount of securities proposed to be sold by persons or entities other
than the Company that the underwriters reasonably believe compatible with the success of the offering, then, except as otherwise agreed by the Company with holders of securities (other than Registrable Securities) to be included in such
registration, the Company shall be required to include in the offering only that number of such securities, including Registrable Securities, which the underwriters believe will be compatible with the success of the offering, but in no event shall
(i) the Company be required to exclude from such registration shares held by any person who is entitled to include shares in such registration statement pursuant to an agreement other than this Agreement, except to the extent such other

  
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agreement permits the Company to exclude such shares from such registration before excluding or reducing pro rata the Holders’ Registrable Securities, (ii) in the IPO the total amount
of securities, including Registrable Securities requested by the Holders to be included in the IPO, be reduced unless, subject to the immediately preceding clause (i), all other securities of the Company held by other holders of securities of the
Company are first entirely excluded from the IPO; or (iii) any shares being sold by a holder exercising a demand registration right similar to that granted in Section 2(a) be excluded from such offering. 

(h)    Delay of Registration. No Holder shall have any right to obtain or seek an injunction
restraining or otherwise delaying any such registration as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 2 unless such injunction is sought by Holders of a majority of the
Registrable Securities. 
 (i)    Indemnification. If any Registrable Securities are
included in a registration statement under this Section 2: 
 (1)    To the extent permitted by law, the Company
will indemnify and hold harmless each Holder, the partners, officers, members, investment advisors, Affiliates and directors of each Holder, any underwriter (as defined in the 1933 Act) for such Holder and each person, if any, who controls such
Holder or underwriter within the meaning of the 1933 Act or the 1934 Act against any losses, claims, damages, or liabilities (joint or several) to which they may become subject under the 1933 Act, the 1934 Act or other federal or state law, insofar
as such losses, claims, damages, liabilities, or expenses (or actions in respect thereof) arise out of or are based upon any of the following statements, omissions or violations of the Company (collectively a “Violation”): (i) any untrue
statement or alleged untrue statement of a material fact contained in a registration statement filed pursuant to this Agreement, including any preliminary prospectus or final prospectus contained therein or any amendments or supplements thereto,
(ii) the 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 of the 1933 Act, the 1934 Act,
any state securities law or any rule or regulation promulgated under the 1933 Act, the 1934 Act or any state securities law in connection with the Company’s performance of its obligations under this Agreement; and the Company will pay to each
such Holder, the partners, officers, members, investment advisors, Affiliates and directors of each such Holder, each such underwriter or controlling person, as incurred, any legal or other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, damage, liability, expense, or action; provided, however, that the indemnity agreement contained in this Section 2(i)(1) shall not apply to amounts paid in settlement of any such loss,
claim, damage, liability, expense, or action if such settlement is effected without the consent of the Company (which consent shall not be unreasonably withheld), nor shall the Company be liable in any such case to a particular such person for any
such loss, claim, damage, liability, or action to the extent that it arises out of or is based upon a Violation which occurs (i) in reliance upon and in conformity with written information furnished expressly for use in connection with such
registration by such person, (ii) due to the failure of a Holder to comply in any material respect with the covenants and agreements contained in this Agreement with respect to the sale of Registrable Securities, and (iii) due to an untrue
statement or omission in any prospectus that is corrected in any subsequent prospectus, or supplement or amendment thereto, that was delivered to such Holder prior to the pertinent sale or sales by such Holder and not delivered by such Holder to the
individual or entity to which it made such sale(s) prior to such sale(s). 

  
 11 

 (2)    To the extent permitted by law, each selling Holder will
indemnify and hold harmless the Company, 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 1933 Act or the 1934 Act, any underwriter, any
other Holder selling securities in such registration statement, any of such other Holder’s partners, officers, or directors, and any person who controls any such other Holder or underwriter within the meaning of the 1933 Act or the 1934 Act,
against any losses, claims, damages, liabilities, or expenses (joint or several) to which any of the foregoing persons may become subject, under the 1933 Act, the 1934 Act or other federal or state law, insofar as such losses, claims, damages, or
liabilities (or actions in respect thereto) arise out of or are based upon any Violation by such Holder, in each case to the extent (and only to the extent) that such Violation occurs in reliance upon and in conformity with written information
furnished by such Holder and stated by such Holder to be expressly for use in connection with such registration (the “Holder’s Information”); and each such Holder will pay, as incurred, any legal or other expenses reasonably incurred
by any person intended to be indemnified pursuant to this Section 2(i)(2), in connection with investigating or defending any such loss, claim, damage, liability, expense, or action if determined by final judgment (not subject to appeal) of a
court of competent jurisdiction that there was such a Violation; provided, however, that the indemnity agreement contained in this Section 2(i)(2) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability
or action if such settlement is effected without the prior consent of such Holder, which consent shall not be unreasonably withheld, nor shall a Holder be liable in any such case to a particular such person for any such loss, claim, damage,
liability, or action to the extent that it arises out of or is based upon a Violation which (i) occurs due to the failure of the Company to comply with the covenants and agreements contained in this Agreement with respect to the sale of
Registrable Securities or (ii) arises from an untrue statement or omission in any prospectus that is based on such Holder’s Information and as to which such Holder shall have provided to the Company corrected Holder’s Information and
the Company shall not have corrected such prospectus prior to the pertinent sale or sales by for which the Violation occurred; provided further, that, in no event shall any Holder be liable for indemnity under this Section 2(i)(2) or
otherwise in an amount that exceeds the net proceeds from the offering received by such Holder. 
 (3)    Promptly after
receipt by an indemnified party under this Section 2(i) of notice of the commencement of any action (including any governmental action), such indemnified party will, if a claim in respect thereof is to be made against any indemnifying party
under this Section 2(i), deliver to the indemnifying party a written notice of the commencement thereof and the indemnifying party shall have the right to participate in, and, to the extent the indemnifying party so desires, jointly with any
other indemnifying party similarly noticed, to assume the defense thereof with counsel mutually satisfactory to the parties. After notice from the indemnifying party to any indemnified party(s) of the indemnifying party’s election to assume the
defense thereof, the indemnifying party shall not be liable to such indemnified party(s) for any legal expenses subsequently incurred by such indemnified party in connection with the defense thereof; provided, however, that an indemnified
party shall have the right to retain its own 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, in the opinion of counsel to
the indemnified party, be inappropriate due to actual or potential differing interests between such indemnified party 

  
 12 

 
and any other party represented by such counsel in such proceeding; provided, further, that the indemnifying party shall not be obligated to assume the expenses of more than one counsel to
represent all indemnified parties. If any indemnified party is entitled to such separate counsel, such counsel shall be required to cooperate with other counsel representing the indemnifying parties in such action if any indemnifying party is
required to pay or reimburse the costs of such separate counsel. The failure to deliver written notice to the indemnifying party within a reasonable time of the commencement of any such action, if materially prejudicial to its ability to defend such
action, shall relieve such indemnifying party of any liability to the indemnified party under this Section 2(i), but the failure so to deliver written notice to the indemnifying party will not relieve it of any liability that it may have to any
indemnified party otherwise than under this Section 2(i). 
 If the indemnification provided for in this Section 2(i) is held by a
court of competent jurisdiction to be unavailable to an indemnified party with respect to any losses, claims, damages, liabilities, or expenses referred to herein, the indemnifying party, in lieu of indemnifying such indemnified party thereunder,
shall to the extent permitted by applicable law contribute to the amount paid or payable by such indemnified party as a result of such loss, claim, damage, liability, or expenses in such proportion as is appropriate to reflect the relative fault of
the indemnifying party on the one hand and of the indemnified party on the other in connection with the Violation(s) that resulted in such loss, claim, damage liability, or expense, as well as any other relevant equitable considerations. The
relative fault of the indemnifying party and of the indemnified party shall be determined by a court of law by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission to state 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 no event shall any contribution by a Holder hereunder exceed the proceeds from the offering received by such Holder. 

(4)    The obligations of the Company and Holders under this Section 2(i) shall survive the completion of any
offering of Registrable Securities in a registration statement under this Section 2, and otherwise. No indemnifying party, in the defense of any such claim or litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by the claimant or plaintiff to such indemnified party of a release from all liability in respect to such claim or litigation. The
rights to indemnification and contribution in this Section 2(i) shall be in addition to and not in lieu of any other rights arising under applicable law. 

(j)    Rule 144; Reports Under Securities Exchange Act of 1934. With a view to making
available to the Holders the benefits of Rule 144 promulgated under the 1933 Act 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, after the effective date of the first registration statement filed by the Company for the offering of its securities to the general public, the Company agrees to: 

(1)    make and keep public information available, as those terms are understood and defined in Rule 144, at all times
after ninety (90) days after such effective date; 

  
 13 

 (2)    take such action, including the voluntary registration of its
Class 1 Stock under Section 12 of the 1934 Act, as is necessary to enable the Holders to utilize Form S-3 for the sale of their Registrable Securities, such action to be taken as soon as practicable
after the registration statement filed by the Company for its IPO is declared effective, subject to the rules and regulations applying to the use of a Form S-3; 

(3)    file with the SEC in a timely manner all reports and other documents required of the Company under the 1933 Act and
the 1934 Act; and 
 (4)    furnish to any Holder, so long as the Holder owns any Registrable Securities, forthwith upon
request (i) a written statement by the Company that it has complied with the reporting requirements of Rule 144 under the 1933 Act (at any time after ninety (90) days following the effective date of the first registration statement filed
by the Company), the 1933 Act and the 1934 Act (at any time after it 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 it 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 which permits the selling of any such securities without registration or pursuant to such form. 

(k)    Assignment of Registration Rights. The rights to cause the Company to register
Registrable Securities pursuant to this Section 2 may be assigned by a Holder to a transferee or assignee who acquires all or any part of a Holder’s Registrable Securities (including through holding any Subject Stock Equivalents);
provided the Company is, within a reasonable time after such transfer, furnished with written notice of the name and address of such transferee or assignee and the securities with respect to which such registration rights are being assigned;
and provided, further, that such assignment shall be effective only if immediately following such transfer the further public disposition of such securities by the transferee or assignee is restricted under the 1933 Act. 

(l)    No Limitation on Subsequent Registration Rights. From and after the date of this
Agreement, the Company shall have the right, without any consent or approval of, or notice to, the Holders, to enter into any agreement with any holder or prospective holder of any securities of the Company (i) which would allow such holder or
prospective holder to include such securities in any registration filed under Sections 2(a), 2(b) or 2(c) hereof, or (ii) which would restrict the right of the Holders to exercise their rights under Section 2(b) with respect to any
registration that the Company effects for any such holder in order to afford similar rights to other holders or prospective holders having priority over the rights of the Holders hereunder. 

(m)    Mergers, Etc. The Company shall not, directly or indirectly, enter into any merger,
consolidation or reorganization in which the Company shall not be the surviving entity unless the proposed surviving entity shall, prior to such merger, consolidation or reorganization, agree in writing to assume the obligations of the Company under
this Section 2, and for that purpose references hereunder to Registrable Securities shall be deemed to be references to the securities which the Holders would be entitled to receive in exchange for Registrable Securities under the terms of any
such merger, consolidation or reorganization or to receive upon conversion of securities the Holders would be entitled to receive in exchange for shares of Class 1 Stock under 

  
 14 

 
the terms of any such merger, consolidation or reorganization; provided, however, that the provisions of this Section 2(m) shall not apply in the event of any merger, consolidation,
or reorganization in which the Company is not the surviving entity if all members are entitled to receive in exchange for their Class 1 Stock and Registrable Securities consideration consisting solely of (i) cash, (ii) securities of the
acquiring entity which may be immediately sold to the public without further registration under the 1933 Act, and/or (iii) securities of the acquiring entity which the acquiring entity has agreed to register within ninety (90) days after
completion of the transaction for resale to the public pursuant to the 1933 Act on terms comparable to this Section 2. 

3.    Miscellaneous Provisions. 

(a)    All Shares Held by Holders. The terms and conditions of this Agreement govern all shares
of Class 1 Stock, and shares of Class 1 Stock issuable upon conversion or exercise of any Subject Stock Equivalent, held by any Holder at the time it becomes a party to this Agreement and all such shares of Class 1 Stock acquired, or
issuable in respect of Subject Stock Equivalents acquired, by such Holder subsequent to the date such Holder becomes a party to this Agreement and before the Company’s IPO, except to the extent the rights of the holder of such shares to
registration under the 1933 Act are expressly governed by a separate agreement. A person who acquires beneficial ownership of Registrable Securities from a Holder and who becomes a party to this Agreement in accordance with Section 2(k) shall
thereby become a Holder for purposes of this Agreement. 
 (b)    Successors and Assigns.
The terms and conditions of this Agreement shall inure to the benefit of and be binding upon the respective successors and permitted transferees and permitted assigns of the parties. 

(c)    Governing Law. This Agreement shall be governed by and construed under the internal
laws of the State of New York as applied to agreements among residents of the State of New York entered into and to be performed entirely within the State of New York, without reference to principles of conflict of laws or choice of laws. 

(d)    Counterparts; Effectiveness. This Agreement may be executed in counterparts and by the
parties hereto on separate counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. This Agreement shall become effective when duly executed and delivered by the Company and any
Holder. Thereafter, any other Holder may become a participant by executing and delivering to the Company a counterpart of this Agreement. 

(e)    Headings. The headings and captions used in this Agreement are used for
convenience only and are not to be considered in construing or interpreting this Agreement. All references in this Agreement to sections, paragraphs, exhibits and schedules shall, unless otherwise provided, refer to sections and paragraphs hereof
and exhibits and schedules attached hereto, all of which are incorporated herein by this reference. 

(f)    Stock Splits, etc. All share numbers used in this Agreement are subject to adjustment
in the case of any stock split, reverse stock split, combination or similar events. 

  
 15 

 (g)    Notices and Requests. Unless
otherwise specifically provided in this Agreement, any notice or request required or permitted under this Agreement shall be given in writing and shall be deemed effectively given on the earliest of (i) when received, (ii) upon personal
delivery to the party to be notified, (iii) upon delivery via facsimile so long as confirmation of receipt is received from the receiving facsimile machine, (iv) one day after being deposited with an overnight courier service,
(v) three days after deposit with the United States Postal Service, by certified mail, postage prepaid and addressed to the party to be notified at the address set forth on its signature page to this Agreement, or (vi) if delivered by e-mail message to the address set forth on such party’s signature page to this Agreement, at the time at which confirmation of receipt is generated by the recipient opening the
e-mail communication and creating a record of receipt of the transmission, or at such other address as such party may designate by ten (10) days advance notice to all other parties. 

(h)    Amendments and Waivers. (1) Any term of this Agreement may be amended, the
observance of any term of this Agreement may be waived (either generally or in a particular instance and either retroactively or prospectively) and any persons may be added as parties hereto, only by an instrument in writing signed by (i) the
Company and (ii) Holders who hold a majority in interest of the Registrable Securities held by all Holders. Notwithstanding the foregoing, the Company and the Holders agree that this Agreement shall be automatically amended without further
action by the Company or any Holders to add as additional parties (x) from time to time any person who purchases shares of Class 1 Stock from the Company after the date the initial Holders become parties hereto and who executes and
delivers to the Company a counterpart of this Agreement, in which case the Company may amend Exhibit A from time to time to include such purchasers and (y) from time to time any transferee of registration rights as contemplated by
Section 2(k) so long as such transferee agrees in writing with the Company to be bound by the terms of this Agreement as a Holder. Any such amendments or waivers will be binding on all parties hereto. 

(2)    (A) Notwithstanding anything otherwise to the contrary contained in this Agreement, the Company may amend or modify
any term or provision in this Agreement from time to time after the Closing in connection with the issuance of any Subject Stock or Subject Stock Equivalents in a financing transaction the principal purpose of which is to raise capital for the
Company if (1) the price per share of Subject Stock issued in such transaction or the price per share of Subject Stock at which the Subject Stock is deemed issued in such transaction is equal to or greater than the Conversion Price in effect on
the date of, and immediately prior to, such issuance and (2) such amendment or modification is approved by (x) a written instrument signed by Holders of outstanding shares of Class 1 Stock that at the time constitute Registrable
Securities who would, in a vote of such holders taken by the Company, be entitled to cast a majority of the votes entitled to be cast by all the Holders with respect to their outstanding shares of Class 1 Stock that at the time are Registrable
Securities, and (y) the Board of Managers. 
 (B)    The issuance by the Company of Subject Stock Equivalents in a
financing transaction the principal purpose of which is to raise capital shall be deemed the issuance at the time of such issuance of Subject Stock Equivalents of the Subject Stock issuable upon the exercise,

  
 16 

 
conversion or exchange of such Subject Stock Equivalents. The price per share at which the shares of Subject Stock are so deemed to have been issued shall be determined by dividing: 

(i)    the total amount, if any, received or receivable by the Company as consideration for the issuance of
such Subject Stock Equivalents, plus the minimum aggregate amount of additional consideration (as set forth in the instruments relating thereto and determined without regard to any provision contained therein for a subsequent adjustment of such
consideration) payable to the Company upon the exercise, conversion or exchange of such Subject Stock Equivalents, by 

(ii)    the maximum number of shares of Subject Stock as set forth in the instruments relating thereto
(determined without regard to any provisions contained therein for a subsequent adjustment of such number) issuable upon the exercise, conversion or exchange of such Subject Stock Equivalents. 

(i)    Severability. If one or more provisions of this Agreement are held to be unenforceable
under applicable law, such provision(s) shall be excluded from this Agreement and the balance of the Agreement shall be interpreted as if such provision(s) were so excluded and shall be enforceable in accordance with its terms to the maximum extent
possible. 
 (j)    Entire Agreement. This Agreement, together with all exhibits and
schedules hereto, constitutes the entire understanding and agreement of the parties with respect to the subject matter hereof and supersedes all prior negotiations, correspondence, agreements, understandings, duties or obligations among the parties
with respect to the subject matter hereof. 
 (k)    Further Assurances. From and after the
date of this Agreement, upon the request of a party, the other parties shall execute and deliver such instruments, documents or other writings as may be reasonably necessary or desirable to confirm and carry out and to effectuate fully the intent
and purposes of this Agreement. 
 [signature page follows] 

  
 17 

 IN WITNESS WHEREOF, the parties have duly executed this Agreement or caused this
Agreement to be duly executed by their respective officers or other representatives thereunto duly authorized as of the day and year first set forth above. 
  

					
	INOZYME PHARMA, LLC
			
		 		 	        By:                 /s/ Axel
Bolte                    
		 		 	Axel Bolte
		 		 	 Chief Executive Officer

and President

 Address: 
 [**] 

Email: [**] 

  
 18 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

					
	Date: June 22, 2016	 		 	
			
	Number of Shares:	 		 	
			
	 1,500,000 Class 1 Stock
	 		 	 /s/ Axel Bolte

		 		 	Axel Bolte

 Address: 
 [**] 

Email: [**] 

  
 19 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

					
	Date: June 22, 2016	 		 	
			
	Number of Shares:	 		 	
			
	 3,000,000 Class l Stock
	 		 	 /s/ Demetrios Braddock

		 		 	Demetrios Braddock

 Address: 
 [**] 

Email: [**] 

  
 20 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

							
	Date: June 22, 2016	 	CHAUTAUQUA CORPORATE SERVICES, LLC        
				
	Number of Shares:	 		 		 	
				
	 500,000
	 		 	By:	 	 /s/ Brian W. Pusch

		 		 		 	Brian W. Pusch
		 		 		 	Managing Member

 Address: 
 [**] 

Email: [**] 

  
 21 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

					
	Date: June 22, 2016	 		 	
			
	Number of Shares:	 		 	
			
	 500,000 Class 1 Stock
	 		 	 /s/ Enrique De LaCruz

		 		 	Enrique De LaCruz

 Address: 
 [**] 

Email: [**] 

  
 22 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

					
	Date: June 22, 2016	 		 	
			
	Number of Shares:	 		 	
			
	 2,500,000 Class 1 Stock
	 		 	 /s/ Joseph Schlessinger

		 		 	Joseph Schlessinger

 Address: 
 [**] 

Email: [**] 

  
 23 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

			
	Date: June 29, 2016	  	
		
	Number of Shares:	  	
		
	16,667                                     
                                       	  	 /s/ Steven Jungles

		  	Steven Jungles
		  	Trust Dated Nov. 12, 2014

 Address: 
 [**] 

Email: [**] 

  
 24 

 Inozyme Pharma, LLC Confidential 

 

 OMNIBUS SIGNATURE PAGE FOR 

REGISTRATION RIGHTS AGREEMENT 

IN WITNESS WHEREOF, the undersigned has hereby duly executed the Registration Rights Agreement or caused the Registration Rights
Agreement to be hereby duly executed by one of its officers or other representatives thereunto duly authorized, as of the date set forth below. 
  

							
	Date: January 6, 2017	 	YALE UNIVERSITY
			
	Number of Shares:	 		 	
			
	1,000,000                                    
                                        	 	By:	 	 /s/ Jon Soderstrom

		 		 	Name:	 	Jon Soderstrom
		 		 	Title:	 	Managing Director
		 		 		 	Office Cooperative Research

 Address: 
 [**] 

Email: [**] 

  
 25EX-10.3

 Exhibit 10.3 

AMENDED AND RESTATED 

2017 EQUITY INCENTIVE PLAN 

OF 

INOZYME PHARMA, INC. 

 

 TABLE OF CONTENTS 

 

							
	 	 	 	  	PAGE	 
	 1.
	 	 Purpose
	  	 	1	 
	 2.
	 	 Eligibility
	  	 	1	 
	 3.
	 	 Administration and Delegation
	  	 	1	 
	 (a)
	 	 Administration by the Board
	  	 	1	 
	 (b)
	 	 Appointment of Committees
	  	 	2	 
	 (c)
	 	 Delegation to Officers
	  	 	2	 
	 4.
	 	 Stock Available for Awards
	  	 	2	 
	 (a)
	 	 Number of Shares
	  	 	2	 
	 (b)
	 	 Substitute Awards
	  	 	2	 
	 5.
	 	 Stock Options
	  	 	2	 
	 (a)
	 	 General
	  	 	2	 
	 (b)
	 	 Incentive Stock Options
	  	 	3	 
	 (c)
	 	 Exercise Price
	  	 	3	 
	 (d)
	 	 Duration of Options
	  	 	4	 
	 (e)
	 	 Exercise of Options
	  	 	4	 
	 (f)
	 	 Payment Upon Exercise
	  	 	4	 
	 (g)
	 	 Limitation on Repricing
	  	 	5	 
	 6.
	 	 Stock Appreciation Rights
	  	 	5	 
	 (a)
	 	 General
	  	 	5	 
	 (b)
	 	 Measurement Price
	  	 	5	 
	 (c)
	 	 Duration of SARs
	  	 	5	 
	 (d)
	 	 Exercise of SARs
	  	 	5	 
	 (e)
	 	 Limitation on Repricing
	  	 	5	 
	 7.
	 	 Restricted Stock; Restricted Stock Units
	  	 	6	 
	 (a)
	 	 General
	  	 	6	 
	 (b)
	 	 Terms and Conditions for All Restricted Stock Awards
	  	 	6	 
	 (c)
	 	 Additional Provisions Relating to Restricted Stock
	  	 	6	 
	 (d)
	 	 Additional Provisions Relating to Restricted Stock Units
	  	 	7	 
	 8.
	 	 Other Stock-Based Awards
	  	 	7	 
	 (a)
	 	 General
	  	 	7	 
	 (b)
	 	 Terms and Conditions
	  	 	7	 
	 9.
	 	 Adjustments for Changes in Common Stock and Certain Other Events
	  	 	7	 
	 (a)
	 	 Changes in Capitalization
	  	 	7	 
	 (b)
	 	 Reorganization Events
	  	 	8	 
	 10.
	 	 General Provisions Applicable to Awards
	  	 	10	 
	 (a)
	 	 Transferability of Awards
	  	 	10	 
	 (b)
	 	 Documentation
	  	 	10	 
	 (c)
	 	 Board Discretion
	  	 	10	 
	 (d)
	 	 Termination of Status
	  	 	10	 
	 (e)
	 	 Withholding
	  	 	10	 
	 (f)
	 	 Amendment of Award
	  	 	11	 
	 (g)
	 	 Conditions on Delivery of Stock
	  	 	11	 
	 (h)
	 	 Acceleration
	  	 	11	 

							
	 11.
	 	 Miscellaneous
	  	 	11	 
	 (a)
	 	 No Right To Employment or Other Status
	  	 	11	 
	 (b)
	 	 No Rights As Stockholder
	  	 	12	 
	 (c)
	 	 Effective Date and Term of Plan
	  	 	12	 
	 (d)
	 	 Amendment of Plan
	  	 	12	 
	 (e)
	 	 Authorization of Sub-Plans (including Grants to non-U.S. Employees)
	  	 	12	 
	 (f)
	 	 Compliance with Section 409A of the Code
	  	 	12	 
	 (g)
	 	 Limitations on Liability
	  	 	13	 
	 (h)
	 	 Governing Law
	  	 	13	 

  

  
 - ii - 

 AMENDED AND RESTATED 

2017 EQUITY INCENTIVE PLAN 

OF 

INOZYME PHARMA, INC. 

1.    Purpose 
 The
purpose of this Amended and Restated 2017 Equity Incentive Plan (the “Plan”) of Inozyme Pharma, 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 and 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 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”); provided, however, that such other business ventures
shall be limited to entities that, where required by Section 409A of the Code, are eligible issuers of service recipient stock (as defined in Treas. Reg. Section 1.409A-1(b)(5)(iii)(E), or applicable
successor regulation). 
 2.    Eligibility 

All of the Company’s employees, officers and directors, as well as consultants and advisors to the Company (as such terms consultants and
advisors are defined and interpreted for purposes of Rule 701 under the Securities Act of 1933, as amended (the “Securities Act”) (or any successor rule)) are eligible to be granted Awards under the Plan. Each person who is granted
an Award under the Plan is deemed a “Participant.” “Award” means Options (as defined in Section 5), SARs (as defined in Section 6), Restricted Stock (as defined in Section 7), Restricted Stock Units
(as defined in Section 7) and Other Stock-Based Awards (as defined in Section 8). 
 3.    Administration and
Delegation 
 (a)    Administration by the Board. 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 actions and decisions by the Board with respect to the Plan and any Awards shall be made in the Board’s discretion and shall be final and binding on all Participants and any other persons having or
claiming any interest in the Plan or in any Award. 

 (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 (each, a “Committee”). All references in the Plan to the “Board” shall mean the
Board or a Committee 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. 

(c)    Delegation to Officers. Subject to any requirements of applicable law (including as applicable Sections 152
and 157(c) of the General Corporation Law of the State of Delaware), 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 and to
exercise such other powers under the Plan as the Board may determine, provided that the Board shall fix the terms of Awards to be granted by such officers, the maximum number of shares subject to Awards that the officers may grant, and the time
period in which such Awards may be granted; and provided further, 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(f) under the Exchange Act). 

4.    Stock Available for Awards 

(a)    Number of Shares. Subject to adjustment under Section 9, Awards may be made under the Plan for up to
5,018,000 shares of common stock, $0.0001 par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). 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 subject to 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 or to satisfy tax withholding obligations arising with respect to 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, the two immediately preceding sentences 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 subject to each Option, 

  
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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. 
 (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 Inozyme Pharma., Inc., any of Inozyme Pharma.’s present and 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. An Option that is not intended to be an Incentive Stock Option shall be designated non-statutory stock option (a “Nonstatutory Stock
Option).” The Company shall have no liability to a Participant, or any other person, if an Option (or any part thereof) that is intended to be an Incentive Stock Option is not an Incentive Stock Option or if the Company converts 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 Grant Date Fair Market Value (as defined below) of the Common Stock on the date the Option is
granted; provided that if the Board approves the grant of an Option with an exercise price to be determined on a future date, the exercise price shall not be less than 100% of the Grant Date Fair Market Value on such future date. The “Grant
Date Fair Market Value” of a share of Common Stock for purposes of the Plan will be determined as follows: 

(1)    if the Common Stock is not publicly traded, the Board will determine the Fair Market Value for purposes of the Plan
using any measure of value it determines to be appropriate (including, as it considers appropriate, relying on appraisals) in a manner consistent with the valuation principles under Code Section 409A, except as the Board may expressly determine
otherwise; 
 (2)    if the Common Stock is listed on a national securities exchange, the closing sale price (for the
primary trading session) on the date of grant; or 
 (3)    if the Common Stock is not listed on any such exchange, the
average of the closing bid and asked prices as reported by an authorized OTCBB market data vendor as listed on the OTCBB website (otcbb.com) on the date of grant. 

For any date that is not a trading day, the Grant Date Fair Market Value of a share of Common Stock for such date will be determined by using
the closing sale price or average of the bid and asked prices, as appropriate, for the immediately preceding trading day and with the timing in the formulas above adjusted accordingly. The Board can substitute a particular time of day or other
measure of “closing sale price” or “bid and asked prices” if appropriate because of exchange or market procedures or can, in its discretion, use weighted averages either on a daily basis or such longer period as complies with
Code Section 409A. 

  
 - 3 - 

 The Board has discretion to determine the Grant Date Fair Market Value for purposes of the
Plan, and all Awards are conditioned on the applicable Participant’s agreement that the Board’s determination is conclusive and binding even though others might make a different determination. 

(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; provided, however, that no Option will be granted with a term in excess of 10 years. 

(e)    Exercise of Options. Options may be exercised by delivery to the Company of a notice of exercise in a form
of notice (which may be electronic) approved by the Company, together with payment in full (in the manner specified in Section 5(f)) of the exercise price 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 or approved by the Board, in its discretion, 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 discretion, by delivery (either by actual delivery or attestation) of shares of Common Stock owned by the Participant valued at their fair market value (valued in the
manner determined by (or in a manner approved by) the Board), 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 provided for in the applicable Nonstatutory Stock Option agreement or approved by the Board in its
discretion, by delivery of a notice of “net exercise” to the Company, as a result of which the Participant would receive (i) the number of shares underlying the portion of the Option being exercised, less (ii) such number of
shares as is equal to (A) the aggregate exercise price for the portion of the Option being exercised divided by (B) the fair market value of the Common Stock (valued in the manner determined by (or in a manner approved by) the Board) on
the date of exercise; 
 (5)    to the extent permitted by applicable law and provided for in the applicable Option
agreement or approved by the Board, in its discretion, by payment of such other lawful consideration as the Board may determine; or 

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

(g)    Limitation on Repricing. Unless such action is approved by the Company’s stockholders, the Company may
not (except as provided under Section 9): (1) amend any outstanding Option to provide an exercise price per share that is lower than the then-current exercise price per share of such outstanding Option, (2) cancel any outstanding Option or
option granted outside this Plan and grant in substitution therefor new Awards under this Plan (other than Awards granted pursuant to Section 4(b)) 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 Option or other option, (3) cancel in exchange for a cash payment any outstanding Option with an exercise price per share above the then-current fair market value
of the Common Stock (valued in the manner determined by (or in the manner approved by) the Board), or (4) take any other action under this Plan that constitutes a “repricing” within the meaning of the applicable rules of any stock
exchange or public trading market (a “Stock Exchange”) on which the Common Stock is listed or traded. 
 6.    Stock
Appreciation Rights 
 (a)    General. The Board may grant Awards consisting of stock appreciation rights
(“SARs”) entitling the Participant, upon exercise, to receive an amount of Common Stock or cash or a combination thereof (such form to be determined by the Board) determined by reference to appreciation, from and after the date of
grant, in the fair market value of a share of Common Stock (valued in the manner determined by (or in a manner approved by) the Board) over the measurement price established pursuant to Section 6(b). The date as of which such appreciation is
determined shall be the exercise date. 
 (b)    Measurement Price. The Board shall establish the measurement
price of each SAR and specify it in the applicable SAR agreement. The measurement price shall not be less than 100% of the Grant Date Fair Market Value of a share of Common Stock on the date the SAR is granted; provided, that if the Board
approves the grant of an SAR effective as of a future date, the measurement price shall not be less than 100% of the Grant Date Fair Market Value on such future date. 

(c)    Duration of SARs. Each SAR shall be exercisable at such times and subject to such terms and conditions as
the Board may specify in the applicable SAR agreement; provided, however, that no SAR will be granted with a term in excess of 10 years. 

(d)    Exercise of SARs. SARs may be exercised by delivery to the Company of a notice of exercise in a form (which
may be electronic) approved by the Company, together with any other documents required by the Board. 

(e)    Limitation on Repricing. Unless such action is approved by the Company’s stockholders, the Company may
not (except as provided under Section 9): (1) amend any outstanding SAR to provide a measurement price per share that is lower than the then-current measurement price per share of such outstanding SAR, (2) cancel any outstanding SAR or any
stock appreciation right granted outside this Plan and grant in substitution therefor new Awards under this Plan (other than Awards granted pursuant to Section 4(b)) covering the same or a 

  
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different number of shares of Common Stock and having an exercise or measurement price per share lower than the then-current measurement price per share of the cancelled SAR or other stock
appreciation right, (3) cancel in exchange for a cash payment any outstanding SAR with a measurement price per share above the then-current fair market value of the Common Stock (valued in the manner determined by (or in the manner approved by)
the Board), or (4) take any other action under this Plan that constitutes a “repricing” within the meaning of the applicable rules of any Stock Exchange. 

7.    Restricted Stock; Restricted Stock Units 

(a)    General. The Board may grant Awards entitling Participants 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
Participant 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. The Board may also grant Awards
entitling the Participant 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. Unless otherwise provided in the applicable Award agreement, any dividends (whether paid in cash,
stock or property) declared and paid by the Company with respect to shares of Restricted Stock (“Accrued Dividends”) shall be paid to the Participant only if and when such shares become free from the restrictions on transferability
and forfeitability that apply to such shares. Each payment of Accrued Dividends will be made no later than the end of the calendar year in which the dividends are paid to stockholders of that class of stock or, if later, the 15th day of the third
month following the lapsing of the restrictions on transferability and the forfeitability provisions applicable to the underlying shares of Restricted Stock. 

(2)    Stock Certificates. The Company may require that any stock certificates issued in respect of shares of
Restricted Stock, as well as dividends or distributions paid on such 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 Participant’s Designated Beneficiary. “Designated
Beneficiary” means (i) 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 or (ii) in the
absence of an effective designation by a Participant, “Designated Beneficiary” means the Participant’s estate. 

  
 - 6 - 

 (d)    Additional Provisions Relating to Restricted Stock Units.

 (1)    Settlement. Upon the vesting of and/or lapsing of any other restrictions (i.e., settlement) with respect
to each Restricted Stock Unit, the Participant shall be entitled to receive from the Company the number of shares of Common Stock specified in the Award agreement or (if so provided in the applicable Award agreement or otherwise determined by the
Board) an amount of cash equal to the fair market value (valued in the manner determined by (or in a manner approved by) the Board) of such number of shares of Common Stock or a combination thereof. The Board may, in its discretion, provide that
settlement of Restricted Stock Units shall be deferred, on a mandatory basis or at the election of the Participant in a manner that complies with Section 409A of the Code. 

(2)    Voting Rights. A Participant shall have no voting rights with respect to any Restricted Stock Units. 

(3)    Dividend Equivalents. The Award agreement for Restricted Stock Units may provide Participants with the right
to receive an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of Common Stock (“Dividend Equivalents”). Dividend Equivalents may be settled in cash and/or shares of
Common Stock and may be subject to the same restrictions on transfer and forfeitability as the Restricted Stock Units with respect to which paid, in each case to the extent provided in the applicable Award agreement. 

8.    Other Stock-Based Awards 

(a)    General. The Board may grant 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 (“Other Stock-Based Awards”). 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. 

(b)    Terms and Conditions. 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. 
 9.    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 the Plan, (ii) the number and class of securities and exercise price per share of each outstanding Option, (iii) the share
and per-share provisions and the measurement price of each outstanding SAR, (iv) the number of shares subject to and the repurchase price per share subject to each outstanding Award of Restricted Stock
and (v) the share and per-share-related provisions and the purchase price, if any, of each outstanding Award of Restricted Stock Units and each outstanding Other Stock-Based Award, shall be equitably
adjusted by the Company (or substituted Awards 

  
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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 transfer or disposition of all
of the Common Stock of the Company for cash, securities or other property pursuant to a share exchange or other transaction or (c) any liquidation or dissolution of the Company. 

(2)    Consequences of a Reorganization Event on Awards Other than Restricted Stock. 

(i)    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 on such terms as the Board determines (except to the extent specifically provided otherwise in an applicable Award agreement or another agreement between the Company and the
Participant): (i) provide that such 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 all of the Participant’s unexercised and/or unvested Awards will terminate immediately prior to the consummation of such Reorganization Event unless exercised by the Participant (to the extent then exercisable) within a specified period
following the date of such notice, (iii) provide that outstanding Awards shall become exercisable, 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 Participants with respect to each Award held by a Participant equal to (A) the number of shares of Common Stock subject to the vested portion of the Award (after giving effect to any
acceleration of vesting that occurs upon or immediately prior to such Reorganization Event) multiplied by (B) the excess, if any, of (I) the Acquisition Price over (II) the exercise, measurement or purchase price of such Award and any
applicable tax withholdings, in exchange for the termination of such Award, (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, measurement or purchase price thereof and any applicable tax withholdings) and (vi) any combination of the foregoing. In taking any of the actions permitted under this Section 9(b)(2), 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. 

  
 - 8 - 

 (ii)    Notwithstanding the terms of Section 9(b)(2)(i), in the
case of outstanding Restricted Stock Units that are subject to Section 409A of the Code: (i) if the applicable Restricted Stock Unit agreement provides that the Restricted Stock Units shall be settled upon a “change in control
event” within the meaning of Treasury Regulation Section 1.409A-3(i)(5)(i), and the Reorganization Event constitutes such a “change in control event”, then no assumption or substitution
shall be permitted pursuant to Section 9(b)(2)(i) and the Restricted Stock Units shall instead be settled in accordance with the terms of the applicable Restricted Stock Unit agreement; and (ii) the Board may only undertake the actions set
forth in clauses (iii), (iv) or (v) of Section 9(b)(2)(i) if the Reorganization Event constitutes a “change in control event” as defined under Treasury Regulation
Section 1.409A-3(i)(5)(i) and such action is permitted or required by Section 409A of the Code; if the Reorganization Event is not a “change in control event” as so defined or such action
is not permitted or required by Section 409A of the Code, and the acquiring or succeeding corporation does not assume or substitute the Restricted Stock Units pursuant to clause (i) of Section 9(b)(2)(i), then the unvested Restricted
Stock Units shall terminate immediately prior to the consummation of the Reorganization Event without any payment in exchange therefor. 

(iii)    For purposes of Section 9(b)(2)(i), an Award (other than Restricted Stock) shall be considered assumed if,
following consummation of the Reorganization Event, such Award confers the right to purchase or receive pursuant to the terms of such Award, for each share of Common Stock subject to the Award 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 or settlement of the Award to consist solely of such number of shares of common stock of the acquiring or succeeding corporation (or an affiliate thereof) that the Board determined to be equivalent in value (as of the date
of such determination or another date specified 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. Upon the occurrence of a Reorganization Event
other than a liquidation or dissolution of the Company, the repurchase and other rights of the Company with respect to outstanding Restricted Stock 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 such Restricted Stock;
provided, however, that the Board may provide for termination or deemed satisfaction of such repurchase or other rights under the instrument evidencing any Restricted Stock or any other agreement between a Participant and the Company,
either initially or by amendment, or provide for forfeiture of such Restricted Stock if issued at no cost. 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 

  
 - 9 - 

 
evidencing any Restricted Stock or any other agreement between a Participant and the Company, all restrictions and conditions on all Restricted Stock then outstanding shall automatically be
deemed terminated or satisfied. 
 10.    General Provisions Applicable to Awards. 

(a)    Transferability of Awards. Awards (or any interest in an Award, including, prior to exercise, any interest in
shares of Common Stock issuable upon exercise of an Option or SAR) shall not be sold, assigned, transferred (including by establishing any short position, put equivalent position (as defined in Rule 16a-1
issued under the Exchange Act) or call equivalent position (as defined in Rule 16a-1 issued under the Exchange Act)), pledged, hypothecated or otherwise encumbered by the person to whom they are granted,
either voluntarily or by operation of law, and, during the life of the Participant, shall be exercisable only by the Participant; except that Awards, other than Awards subject to Section 409A of the Code, may be transferred to family members
(as defined in Rule 701(c)(3) under the Securities Act) through gifts or (other than Incentive Stock Options) domestic relations orders or to an executor or guardian upon the death or disability of the Participant. The Company shall not be required
to recognize any such permitted transfer until such time as such permitted transferee shall deliver to the Company a written instrument, as a condition to such transfer, in form and substance satisfactory to the Company confirming that such
transferee shall be bound by all of the terms and conditions of the Award. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees. For the avoidance of doubt, nothing contained in this
Section 10(a) shall be deemed to restrict a transfer to the Company. 
 (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 elect 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, vesting or release from forfeiture of an Award or at the same time as payment of the exercise or purchase price unless the Company

  
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determines otherwise. If provided for in an Award or approved by the Board in its discretion, a Participant may satisfy such tax obligations in whole or in part by delivery (either by actual
delivery or attestation) of shares of Common Stock, including shares retained from the Award creating the tax obligation, valued at their fair market value (valued in the manner determined by (or in a manner approved by) the Company); 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), except that, to the extent that the Company is able to retain shares of Common Stock having a fair market
value (valued in the manner determined by (or in a manner approved by) the Company) that exceeds the statutory minimum applicable withholding tax without financial accounting implications or the Company is withholding in a jurisdiction that does not
have a statutory minimum withholding tax, the Company may retain such number of shares of Common Stock (up to the number of shares having a fair market value (valued in the manner determined by (or in a manner approved by) the Company) equal to the
maximum individual statutory rate of tax) as the Company shall determine in its discretion to satisfy the tax liability associated with any Award. Shares used to satisfy tax withholding requirements cannot be subject to any repurchase, forfeiture,
unfulfilled vesting or other similar requirements. 
 (f)    Amendment of Award. Except as otherwise provided in
Sections 5(g) and 6(e) with respect to repricings and Section 11(d) with respect to actions requiring stockholder approval, 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, does not materially and adversely affect the Participant’s rights under the Plan or (ii) the change is permitted under Section 9. 

(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 issued or 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 regulations 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 whole
or in part, free of some or all restrictions or conditions, or otherwise realizable in whole or in part, as the case may be. 

11.    Miscellaneous. 

(a)    No Right To Employment or Other Status. No person shall have any claim or right to be granted an Award by
virtue of the adoption of the Plan, and the grant of an Award shall not 

  
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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. 
 (d)    Amendment of Plan. The Board may amend, suspend
or terminate the Plan or any portion thereof at any time; provided that (i) 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; and (ii) no amendment that would require stockholder approval under the applicable rules of any Stock
Exchange may be made effective unless and until the Company’s stockholders approve such amendment. Unless otherwise specified in the amendment, any amendment to the Plan adopted in accordance with this Section 11(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, taking into account any related action, does not materially and adversely affect the rights of
Participants under the Plan. No Award shall be made that is conditioned upon stockholder approval of any amendment to the Plan unless the Award provides that (1) it will terminate or be forfeited if stockholder approval of such amendment is not
obtained within no more than 12 months from the date of the Award and (2) it may not be exercised or settled (or otherwise result in the issuance of Common Stock) prior to such stockholder approval. 

(e)    Authorization of Sub-Plans (including Grants to non-U.S. Employees). The Board may from time to time establish one or more sub-plans under the Plan for purposes of satisfying applicable securities, tax or other laws of
various jurisdictions. The Board shall establish such sub-plans by adopting supplements to the 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 Section 409A of the Code. If and to the extent (i) any portion of
any payment, compensation or other benefit provided to a Participant pursuant to the Plan in connection with Participant’s employment termination constitutes “nonqualified deferred 

  
 - 12 - 

 
compensation” within the meaning of Section 409A of the Code and (ii) the Participant is a specified employee as defined in Section 409A(a)(2)(B)(i) of the Code, in each case
as determined by the Company in accordance with its procedures, by which determinations the Participant (through accepting the Award) agrees that the Participant is bound, such portion of the payment, compensation or other benefit shall not
be paid before the day that is six months plus one day after the date of “separation from service” (as determined under Section 409A of the Code) (the “New Payment Date”), except as Section 409A of the Code may
then permit. The aggregate of any payments that otherwise would have been paid to the Participant during the period between the date of separation from service and the New Payment Date shall be paid to the Participant in a lump sum on such New
Payment Date, and any remaining payments will be paid on their original schedule. 
 The Company makes no representations or warranty and shall have no
liability to the Participant or any other person if any provisions of or payments, compensation or other benefits under the Plan are determined to constitute nonqualified deferred compensation subject to Section 409A of the Code but do not to
satisfy the conditions of that section. 
 (g)    Limitations on Liability. Notwithstanding any other
provisions of the Plan, no individual acting as a director, officer, other employee, or agent of the Company will be liable to any Participant, former Participant, spouse, beneficiary, or any other person for any claim, loss, liability, or
expense incurred in connection with the Plan, nor will such individual be personally liable with respect to the Plan because of any contract or other instrument such individual executes in such individual’s capacity as a director, officer,
other employee, or agent of the Company. The Company will indemnify and hold harmless each director, officer, other employee, or agent of the Company to whom any duty or power relating to the administration or interpretation of the Plan has been or
will be delegated, against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Board’s approval) arising out of any act or omission to act concerning the Plan unless
arising out of such person’s own fraud or bad faith. 
 (h)    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 the State of Delaware. 
 * * * * 

  
 - 13 - 

 INOZYME PHARMA, INC. 

AMENDED AND RESTATED 

2017 EQUITY INCENTIVE PLAN 

CALIFORNIA SUPPLEMENT 

Pursuant to Section 11(e) of the Plan, the Board has adopted this supplement for purposes of satisfying the requirements of
Section 25102(o) of the California Law: 
 Any Awards granted under the Plan to a Participant who is a resident of the State of
California on the date of grant (a “California Participant”) shall be subject to the following additional limitations, terms and conditions: 

1.    Additional Limitations on Options. 

(a)    Maximum Duration of Options. No Options granted to California Participants shall have a term in excess of 10
years measured from the Option grant date. 
 (b)    Minimum Exercise Period Following Termination. Unless a
California Participant’s employment is terminated for cause (as defined by applicable law, the terms of the Plan or option grant or a contract of employment), in the event of termination of employment of such Participant, such Participant shall
have the right to exercise an Option, to the extent that such Participant is entitled to exercise such Option on the date employment terminated, until the earlier of: (i) at least six months from the date of termination, if termination was
caused by such Participant’s death or disability, (ii) at least 30 days from the date of termination, if termination was caused other than by such Participant’s death or disability and (iii) the Option expiration date. 

2.    Additional Limitations for Other Stock-Based Awards. The terms of all Awards granted to a California Participant under
Section 8 of the Plan shall comply, to the extent applicable, with Section 260.140.46 of the California Code of Regulations. 

3.    Additional Limitations on Timing of Awards. No Award granted to a California Participant shall become exercisable, vested or
realizable, as applicable to such Award, unless the Plan has been approved by the holders of a majority of the Company’s outstanding voting securities by the later of (i) within 12 months before or after the date the Plan was adopted by
the Board, or (ii) prior to or within 12 months of the granting of any Award to a California Participant. 
 4.    Additional
Restriction Regarding Recapitalizations, Stock Splits, Etc. For purposes of Section 9 of the Plan, in the event of a stock split, reverse stock split, stock dividend, recapitalization, combination, reclassification or other distribution of
the Company’s securities underlying the Award without the receipt of consideration by the Company, the number of securities purchasable, and in the case of Options, the exercise price of such Options, shall be proportionately adjusted.

 5.    Additional Limitations on Transferability of Awards. Notwithstanding the provisions of Section 10(a) of the Plan,
an Award granted to a California Participant may not be transferred to an executor or guardian upon the disability of the Participant. 
 * *
* * 

 AMENDMENT NO. 1 TO THE 

AMENDED AND RESTATED 2017 EQUITY INCENTIVE PLAN 

OF 
 INOZYME PHARMA, INC.

 The Amended and Restated 2017 Equity Incentive Plan (the “Plan”) of Inozyme Pharma, Inc. (the
“Company”), pursuant to Section 11(d) thereof, is hereby amended as follows: 
 The first sentence of
Section 4(a) of the Plan be and hereby is deleted in its entirety and the following is inserted in lieu thereof: 
 “Subject to
adjustment under Section 9, Awards may be made under the Plan for up to 6,018,000 shares of common stock, $0.0001 par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of
Incentive Stock Options (as defined in Section 5(b)).” 
 Except as set forth above, the remainder of the Plan remains in full
force and effect. 
  

			
		 	 Adopted by the Board of Directors:

December 14, 2017
  

Adopted by the Stockholders:
 January 8, 2018

 AMENDMENT NO. 2 TO THE 

AMENDED AND RESTATED 2017 EQUITY INCENTIVE PLAN 

OF 
 INOZYME PHARMA, INC.

 The Amended and Restated 2017 Equity Incentive Plan (the “Plan”) of Inozyme Pharma, Inc. (the
“Company”), as amended by Amendment No. 1 thereto, pursuant to Section 11(d) thereof, is hereby amended as follows: 

The first sentence of Section 4(a) of the Plan be and hereby is deleted in its entirety and the following is inserted in lieu thereof:

 “Subject to adjustment under Section 9, Awards may be made under the Plan for up to 13,905,000 shares of common stock, $0.0001
par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)).” 

Except as set forth above, the remainder of the Plan remains in full force and effect. 

 

			
		  	 Adopted by the Board of Directors:

November 8, 2018
  

Adopted by the Stockholders:
 November 8, 2018

 AMENDMENT NO. 3 TO THE 

AMENDED AND RESTATED 2017 EQUITY INCENTIVE PLAN 

OF 
 INOZYME PHARMA, INC.

 The Amended and Restated 2017 Equity Incentive Plan (the “Plan”) of Inozyme Pharma, Inc. (the
“Company”), as amended by Amendment No. 1 and Amendment No. 2 thereto, pursuant to Section 11(d) thereof, is hereby amended as follows: 

The first sentence of Section 4(a) of the Plan be and hereby is deleted in its entirety and the following is inserted in lieu thereof:

 “Subject to adjustment under Section 9, Awards may be made under the Plan for up to 20,405,000 shares of common stock, $0.0001
par value per share, of the Company (the “Common Stock”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)).” 

Except as set forth above, the remainder of the Plan remains in full force and effect. 

 

			
		 	 Adopted by the Board of Directors:

March 22, 2019
  

Adopted by the Stockholders:
 March 22, 2019

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