Document:

EX-4.2

 Exhibit 4.2 

AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT 

THIS INVESTORS’ RIGHTS AGREEMENT (this “Agreement”), is made as of April 20, 2021, by and among Affinia
Therapeutics Inc. (f/k/a TDTx Inc.), a Delaware corporation (the “Company”), and each of the investors listed on Schedule A hereto, each of which is referred to in this Agreement as an “Investor”. 

RECITALS: 
 A.
Certain of the Investors (the “Existing Investors”) hold shares of Series A Preferred Stock (as defined below) and Series A-1 Preferred Stock (as defined below) and possess registration
rights, information rights, rights of first offer, and other rights pursuant to that certain Investors’ Rights Agreement dated as of March 12, 2020, by and among the Company and such Existing Investors (the “Prior
Agreement”); 
 B. The Existing Investors are holders of at least a majority of the Registrable Securities (as defined in the
Prior Agreement), and desire to amend and restate the Prior Agreement in its entirety and to accept the rights created pursuant to this Agreement in lieu of the rights granted to them under the Prior Agreement; 

C. The Company and certain of the Investors are parties to that certain Series B Preferred Stock Purchase Agreement of even date
herewith (the “Purchase Agreement”), under which the Company’s and such Investors’ obligations are conditioned upon the execution and delivery of this Agreement by such Investors, Existing Investors holding at least a
majority of the Registrable Securities, and the Company. 
 D. In order to induce the Company to enter into the Purchase Agreement and
to induce the Investors to invest funds in the Company pursuant to the Purchase Agreement, the Investors and the Company hereby agree that this Agreement shall govern the rights of the Investors to cause the Company to register shares of Common
Stock issuable to the Investors, to receive certain information from the Company, and to participate in future equity offerings by the Company, and shall govern certain other matters as set forth in this Agreement. 

The Existing Investors hereby agree that the Prior Agreement shall be amended and restated, and the parties to this Agreement further agree as
follows: 
 1. Definitions. For purposes of this Agreement: 

1.1 “Affiliate” means, with respect to any specified Person, any other Person who, directly or indirectly, controls, is
controlled by, or is under common control with such Person, including, without limitation, any general partner, limited partner, member, manager, managing member, employee, officer, director or trustee of such Person, or any other trust for the
benefit of any of the foregoing or any Affiliate of the foregoing, or any venture capital fund or registered investment company or other investment fund now or hereafter existing that is controlled by one or more general partners, managing members
or investment advisors of, or shares the same management company or investment adviser with, such Person. For purposes of this definition, the term “control” when used with respect to any Person shall mean the power to direct the
management or policies of such Person, directly or indirectly, whether through ownership of voting securities, by contract or otherwise, and the terms “controlling” and “controlled” shall have the meanings correlative to the
foregoing. 

 1.2 “Atlas” means Atlas Venture Fund XI, L.P. 

1.3 “Board of Directors” means the board of directors of the Company. 

1.4 “Certificate of Incorporation” means the Company’s Second Amended and Restated Certificate of Incorporation,
as amended and/or restated from time to time. 
 1.5 “Common Stock” means shares of the Company’s common stock,
par value $0.0001 per share. 
 1.6 “Competitor” means a Person engaged, directly or indirectly (including through
any partnership, limited liability company, corporation, joint venture or similar arrangement (whether now existing or formed hereafter)), in a business that is a competitor of the Company, but shall not include (a) any financial investment
firm or collective investment vehicle that, together with its Affiliates, holds less than 20% of the outstanding equity of any Competitor and does not, nor do any of its Affiliates, have a right to designate any members of the board of directors of
any Competitor, or (b) EcoR1, Farallon, Atlas, F-Prime, NEA, Lonza, MEEI, RA Capital, TCG, Perceptive, or any of their respective Affiliates. 

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

1.8 “Deemed Liquidation Event” means a Deemed Liquidation Event as defined in the Certificate of Incorporation. 

1.9 “Derivative Securities” means any securities or rights convertible into, or exercisable or exchangeable for (in
each case, directly or indirectly), Common Stock, including options and warrants. 
 1.10 “EcoR1” means EcoR1 Capital
Fund, L.P., EcoR1 Capital Fund Qualified, L.P. and EcoR1 Venture Opportunity Fund, L.P., together with their Affiliates. 
 1.11
“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 

1.12 “Excluded Registration” means (i) a registration relating to the sale or grant of securities to employees of
the Company or a subsidiary pursuant to a stock option, stock purchase, equity incentive or similar plan; (ii) a registration relating to an SEC Rule 145 transaction; (iii) a registration on any form that does not include substantially the
same information as would be required to be included in a registration statement covering the sale of the Registrable Securities; or (iv) a registration in which the only Common Stock being registered is Common Stock issuable upon conversion of
debt securities that are also being registered. 

  
 2. 

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

1.15 “Form S-1” means such form under the Securities Act as in effect on
the date hereof or any successor registration form under the Securities Act subsequently adopted by the SEC. 
 1.16 “Form
S-3” means such form under the Securities Act as in effect on the date hereof or any registration form under the Securities Act subsequently adopted by the SEC that permits forward
incorporation of substantial information by reference to other documents filed by the Company with the SEC. 
 1.17 “F-Prime” means F-Prime Capital Partners Life Sciences Fund VI LP. 

1.18 “GAAP” means generally accepted accounting principles in the United States as in effect from time to time. 

1.19 “Holder” means any holder of Registrable Securities who is a party to this Agreement. 

1.20 “Immediate Family Member” means a child, stepchild, grandchild, parent, stepparent, grandparent, spouse, domestic
partner, sibling, mother-in-law, father-in-law, son-in-law, daughter-in-law, brother-in-law, or sister-in-law, including, adoptive relationships, of a natural person referred to herein. 

1.21 “Initiating Holders” means, collectively, Holders who properly initiate a registration request under this
Agreement. 
 1.22 “IPO” means the Company’s first underwritten public offering of its Common Stock under the
Securities Act. 
 1.23 “Lonza” means Lonza Houston, Inc. 

1.24 “Major Investor” means any Investor that, individually or together with such Investor’s Affiliates, holds,
and so long as it holds, at least 1,300,000 shares of Registrable Securities (as adjusted for any stock split, stock dividend, combination, or other recapitalization or reclassification effected after the date hereof). 

1.25 “MEEI” means Massachusetts Eye & Ear Infirmary. 

1.26 “NEA” means New Enterprise Associates 17, L.P. 

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

  
 3. 

 1.28 “Partners” means Partners Innovation Fund, LLC. 

1.29 “Person” means any individual, corporation, partnership, trust, limited liability company, association or other
entity. 
 1.30 “Preferred Directors” means, collectively, the Series A Directors and the Series B Director. 

1.31 “Preferred Stock” means, collectively, shares of the Series A Preferred and Series B Preferred Stock. 

1.32 “Qualified SPAC Transaction” means a Qualified SPAC Transaction as defined in the Certificate of Incorporation.

 1.33 “RA Capital” means collectively, RA Capital Healthcare Fund, L.P., RA Capital Nexus Fund II, L.P., RA Capital
Management, L.P. and their Affiliates. 
 1.34 “Registrable Securities” means (i) the Common Stock issuable or
issued upon conversion of the Preferred Stock; (ii) any Common Stock, or any Common Stock issued or issuable (directly or indirectly) upon conversion and/or exercise of any other securities of the Company held by the Investors, in each case
acquired by the Investors after the date hereof; (iii) Common Stock held by Lonza on the date hereof; (iv) Common Stock held by MEEI on the date hereof; and (iv) any Common Stock issued as (or issuable upon the conversion or exercise
of any warrant, right, or other security that is issued as) a dividend or other distribution with respect to, or in exchange for or in replacement of, the shares referenced in clause (i), (ii), (iii) or (iv) above, for so long as such shares
are considered Registrable Securities; excluding in all cases, however, any Registrable Securities sold by a Person in a transaction in which the applicable rights under this Agreement are not assigned pursuant to Section 6.1, and excluding for
purposes of Section 2 any shares for which registration rights have terminated pursuant to Section 2.13 of this Agreement. 

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

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

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

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

1.40 “Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated
thereunder. 
 1.41 “Selling Expenses” means all underwriting discounts, selling commissions, and stock transfer
taxes applicable to the sale of Registrable Securities, and fees and disbursements of counsel for any Holder, except for the fees and disbursements of the Selling Holder Counsel borne and paid by the Company as provided in Section 2.6. 

  
 4. 

 1.42 “Series A Director” means any director of the Company that the
holders of record of the Series A Preferred are entitled to elect, exclusively and as a separate class, pursuant to the Certificate of Incorporation. 

1.43 “Series A Preferred” means, collectively, shares of the Series A Preferred Stock and the Series A-1 Preferred Stock. 
 1.44 “Series A Preferred Stock” means shares of the
Company’s Series A Preferred Stock, par value $0.0001 per share. 
 1.45 “Series
A-1 Preferred Stock” means shares of the Company’s Series A-1 Preferred Stock, par value $0.0001 per share. 

1.46 “Series B Director” means any director of the Company that the holders of record of the Series B Preferred Stock
are entitled to elect, exclusively and as a separate class, pursuant to the Certificate of Incorporation. 
 1.47 “Series B
Preferred Stock” means shares of the Company’s Series B Preferred Stock, par value $0.0001 per share. 
 1.48
“SPAC Transaction” means a transaction or series of related transactions in which the Company’s outstanding shares of capital stock are exchanged for or otherwise converted into securities that are publicly listed on a
securities exchange (the “Public Shares”) through a merger, acquisition, business combination, or similar transaction with a special purpose acquisition company or its subsidiary or parent (a “SPAC”). 

1.49 “TCG” means TCG Crossover Fund I, L.P., together with its Affiliates. 

2. Registration Rights. The Company covenants and agrees as follows: 

2.1 Demand Registration. 

(a) Form S-1 Demand. If at any time after the earlier of (i) three years after the
date of this Agreement or (ii) 180 days after the effective date of the registration statement for the IPO, the Company receives a request from Holders of 50% of the Registrable Securities then outstanding that the Company file a Form S-1 registration statement covering the registration of Registrable Securities with an anticipated aggregate offering price, net of Selling Expenses, of at least $20 million, then the Company shall
(x) within 10 days after the date such request is given, give notice thereof (the “Demand Notice”) to all Holders other than the Initiating Holders; and (y) as soon as practicable, and in any event within 60 days after the
date such request is given by the Initiating Holders, file a Form S-1 registration statement under the Securities Act covering all Registrable Securities that the Initiating Holders requested to be registered
and any additional Registrable Securities requested to be included in such registration by any other Holders, as specified by notice given by each such Holder to the Company within 20 days of the date the Demand Notice is given, and in each case,
subject to the limitations of Sections 2.1(c) and 2.3. 

  
 5. 

 (b) Form S-3 Demand. If at any time
when it is eligible to use a Form S-3 registration statement, the Company receives a request from Holders of the Registrable Securities then outstanding that the Company file a Form S-3 registration statement with respect to outstanding Registrable Securities of such Holders having an anticipated aggregate offering price, net of Selling Expenses, of at least $2.5 million, then the Company
shall (i) within 10 days after the date such request is given, give a Demand Notice to all Holders other than the Initiating Holders; and (ii) as soon as practicable, and in any event within 45 days after the date such request is given by
the Initiating Holders, file a Form S-3 registration statement under the Securities Act covering all Registrable Securities requested to be included in such registration by any other Holders, as specified by
notice given by each such Holder to the Company within 20 days of the date the Demand Notice is given, and in each case, subject to the limitations of Sections 2.1(c) and 2.3. 

(c) Notwithstanding the foregoing obligations, if the Company furnishes to Holders requesting a registration pursuant to this
Section 2.1 a certificate signed by the Company’s chief executive officer stating that in the good faith judgment of the Board of Directors it would be materially detrimental to the Company and its stockholders for such registration
statement to either become effective or remain effective for as long as such registration statement otherwise would be required to remain effective, because such action would (i) materially interfere with a significant acquisition, corporate
reorganization, or other similar transaction involving the Company, (ii) require premature disclosure of material information that the Company has a bona fide business purpose for preserving as confidential, or (iii) render the Company
unable to comply with requirements under the Securities Act or Exchange Act, then the Company shall have the right to defer taking action with respect to such filing, and any time periods with respect to filing or effectiveness thereof shall be
tolled correspondingly, for a period of not more than 120 days after the request of the Initiating Holders is given; provided, however, that the Company may not invoke this right more than once in any 12 month period; and provided
further that the Company shall not register any securities for its own account or that of any other stockholder during such 120 day period other than an Excluded Registration. 

(d) The Company shall not be obligated to effect, or to take any action to effect, any registration pursuant to Section 2.1(a)(i)
during the period that is 60 days before the Company’s good faith estimate of the date of filing of, and ending on a date that is 180 days after the effective date of, a Company-initiated registration, provided that the Company is
actively employing in good faith commercially reasonable efforts to cause such registration statement to become effective; (ii) after the Company has effected two registrations pursuant to Section 2.1(a); or (iii) if the Initiating
Holders propose to dispose of shares of Registrable Securities that may be immediately registered on Form S-3 pursuant to a request made pursuant to Section 2.1(b). The Company shall not be obligated to
effect, or to take any action to effect, any registration pursuant to Section 2.1(b)(i) during the period that is 30 days before the Company’s good faith estimate of the date of filing of, and ending on a date that is 90 days after the
effective date of, a Company-initiated registration, provided that the Company is actively employing in good faith commercially reasonable efforts to cause such registration statement to become effective; or (ii) if the Company has
effected two registrations pursuant to Section 2.1(b) within the 12 month period immediately preceding the date of such request. A registration shall not be counted as “effected” for purposes of this Section 2.1(d) until such
time as the applicable registration statement has been declared effective by the SEC, unless the Initiating Holders withdraw their request for such registration, elect not to pay the registration expenses therefor, and forfeit their right to one
demand registration statement pursuant to Section 2.6, in which case such withdrawn registration statement shall be counted as “effected” for purposes of this Section 2.1(d); provided, that if such withdrawal is during a
period the Company has deferred taking action pursuant to Section 2.1(c), then the Initiating Holders may withdraw their request for registration and such registration will not be counted as “effected” for purposes of this
Section 2.1(d). 

  
 6. 

 2.2 Company Registration. If the Company proposes to register (including, for
this purpose, a registration effected by the Company for stockholders other than the Holders) any of its securities under the Securities Act in connection with the public offering of such securities solely for cash (other than in an Excluded
Registration), the Company shall, at such time, promptly give each Holder notice of such registration. Upon the request of each Holder given within 20 days after such notice is given by the Company, the Company shall, subject to the provisions of
Section 2.3, cause to be registered all of the Registrable Securities that each such Holder has requested to be included in such registration. The Company shall have the right to terminate or withdraw any registration initiated by it under this
Section 2.2 before the effective date of such registration, whether or not any Holder has elected to include Registrable Securities in such registration. The expenses (other than Selling Expenses) of such withdrawn registration shall be borne
by the Company in accordance with Section 2.6. 
 2.3 Underwriting Requirements. 

(a) If, pursuant to Section 2.1, the Initiating Holders intend to distribute the Registrable Securities covered by their request
by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to Section 2.1, and the Company shall include such information in the Demand Notice. The underwriter(s) will be selected by the Company and
shall be reasonably acceptable to a majority in interest of the Initiating Holders. In such event, the right of any Holder to include such Holder’s Registrable Securities in such registration shall be conditioned upon such Holder’s
participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting to the extent provided herein. All Holders proposing to distribute their securities through such underwriting shall (together with
the Company as provided in Section 2.4(e)) enter into an underwriting agreement in customary form with the underwriter(s) selected for such underwriting; provided, however, that no Holder (or any of their assignees) shall be
required to make any representations, warranties or indemnities except as they relate to such Holder’s ownership of shares and authority to enter into the underwriting agreement and to such Holder’s intended method of distribution, and the
liability of such Holder shall be several and not joint, and limited to an amount equal to the net proceeds from the offering received by such Holder. Notwithstanding any other provision of this Section 2.3, if the managing underwriter(s)
advise(s) the Initiating Holders in writing that marketing factors require a limitation on the number of shares to be underwritten, then the Initiating Holders shall so advise all Holders of Registrable Securities that otherwise would be
underwritten pursuant hereto, and the number of Registrable Securities that may be included in the underwriting shall be allocated among such Holders of Registrable Securities, including the Initiating Holders, in proportion (as nearly as
practicable) to the number of Registrable Securities owned by each Holder or in such other proportion as shall mutually be agreed to by all such selling Holders; provided, however, that the number of Registrable Securities held by the Holders
to be included in such underwriting shall not be reduced unless all other securities are first entirely excluded from the underwriting. To facilitate the allocation of shares in accordance with the above provisions, the Company or the underwriters
may round the number of shares allocated to any Holder to the nearest 100 shares. 
 (b) In connection with any offering involving an
underwriting of shares of the Company’s capital stock pursuant to Section 2.2, the Company shall not be required to include any of the Holders’ Registrable Securities in such underwriting unless the Holders accept the terms of the
underwriting as agreed upon between the Company and its underwriters, and then only in such quantity as the underwriters in their sole discretion determine will not jeopardize the success of the offering by the Company. If the total number of
securities, including Registrable Securities, requested by stockholders to be included in such offering exceeds the number of securities to be sold (other than by the Company) that the underwriters in their reasonable discretion determine is
compatible with the success of the offering, then the Company shall be required to include in the offering only that number of such securities, including Registrable Securities, which the underwriters and the Company in their sole discretion
determine will not jeopardize the success of the offering. If the underwriters determine that less than all of the Registrable Securities requested to be registered can be included in such offering, then the Registrable Securities that are included
in such offering shall be allocated among the selling Holders in proportion (as nearly as practicable to) the number of Registrable Securities owned by each selling Holder or in such other proportions as shall mutually be agreed to by all such
selling Holders. To facilitate the allocation of shares in accordance with the above provisions, the Company or the underwriters may round the number of shares allocated to any Holder to the nearest 100 shares. Notwithstanding the foregoing, in no
event shall (i) the number of Registrable Securities included in the offering be reduced unless all other securities (other than securities to be sold by the Company) are first entirely excluded from the offering or (ii) the number of
Registrable Securities included in the offering be reduced below 25% of the total number of securities included in such offering, unless such offering is the IPO, in which case the selling Holders may be excluded further if the underwriters make the
determination described above and no other stockholder’s securities are included in such offering. For purposes of the provision in this Section 2.3(b) concerning apportionment, for any selling Holder that is a partnership, limited
liability company, or corporation, the partners, members, retired partners, retired members, stockholders, and Affiliates of such Holder, or the estates and Immediate Family Members of any such partners, retired partners, members, and retired
members and any trusts for the benefit of any of the foregoing Persons, shall be deemed to be a single “selling Holder,” and any pro rata reduction with respect to such “selling Holder” shall be based upon the aggregate number of
Registrable Securities owned by all Persons included in such “selling Holder,” as defined in this sentence. 

  
 7. 

 (c) For purposes of Section 2.1, a registration shall not be counted as
“effected” if, as a result of an exercise of the underwriter’s cutback provisions in Section 2.3(a), fewer than 50% of the total number of Registrable Securities that Holders have requested to be included in such registration
statement are actually included. 
 2.4 Obligations of the Company. Whenever required under this Section 2 to effect the
registration of any Registrable Securities, the Company shall, as expeditiously as reasonably possible: 
 (a) prepare and file with
the SEC a registration statement with respect to such Registrable Securities and use its commercially reasonable best efforts to cause such registration statement to become effective and, upon the request of the Holders of a majority of the
Registrable Securities registered thereunder, keep such registration statement effective for a period of up to 120 days or, if earlier, until the distribution contemplated in the registration statement has been completed; provided, however,
that such 120 day period shall be extended for a period of time equal to the period the Holder refrains, at the request of an underwriter of Common Stock (or other securities) of the Company, from selling any securities included in such
registration, and (ii) in the case of any registration of Registrable Securities on Form S-3 that are intended to be offered on a continuous or delayed basis, subject to compliance with applicable SEC
rules, such one hundred twenty (120) day period shall be extended for up to 90 days, if necessary, to keep the registration statement effective until all such Registrable Securities are sold; 

(b) prepare and file with the SEC such amendments and supplements to such registration statement, and the prospectus used in connection
with such registration statement, as may be necessary to comply with the Securities Act in order to enable the disposition of all securities covered by such registration statement; 

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

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

  
 8. 

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

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

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

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

 2.5 Furnish Information. It shall be a condition precedent to the obligations of the Company to take any action pursuant to
this Section 2 with respect to the Registrable Securities of any selling Holder that such Holder shall furnish to the Company such information regarding itself, the Registrable Securities held by it, and the intended method of disposition of
such securities as is reasonably required to effect the registration of such Holder’s Registrable Securities. 
 2.6 Expenses
of Registration. All expenses (other than Selling Expenses) incurred in connection with registrations, filings, or qualifications pursuant to Section 2, including all registration, filing, and qualification fees; printers’ and
accounting fees; fees and disbursements of counsel for the Company; and the reasonable fees and disbursements, not to exceed $50,000, of one counsel for the selling Holders (“Selling Holder Counsel”), shall be borne and paid by the
Company; provided, however, that the Company shall not be required to pay for any expenses of any registration proceeding begun pursuant to Section 2.1 if the registration request is subsequently withdrawn at the request of the Holders
of a majority of the Registrable Securities to be registered (in which case all selling Holders shall bear such expenses pro rata based upon the number of Registrable Securities that were to be included in the withdrawn registration), unless the
Holders of a majority of the Registrable Securities agree to forfeit their right to one registration pursuant to Sections 2.1(a) or 2.1(b), as the case may be then the Holders shall not be required to pay any of such expenses and shall not forfeit
their right to one registration pursuant to Sections 2.1(a) or 2.1(b). All Selling Expenses relating to Registrable Securities registered pursuant to this Section 2 shall be borne and paid by the Holders pro rata on the basis of the number of
Registrable Securities registered on their behalf. 

  
 9. 

 2.7 Delay of Registration. No Holder shall have any right to obtain or seek an
injunction restraining or otherwise delaying any registration pursuant to this Agreement as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 2. 

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

(a) To the extent permitted by law, the Company will indemnify and hold harmless each selling Holder, and the partners, members,
officers, directors, and stockholders of each such Holder; legal counsel and accountants for each such Holder; any underwriter (as defined in the Securities Act) for each such Holder; and each Person, if any, who controls such Holder or underwriter
within the meaning of the Securities Act or the Exchange Act, against any Damages, and the Company will pay to each such Holder, underwriter, controlling Person, or other aforementioned Person any legal or other expenses reasonably incurred thereby
in connection with investigating or defending any claim or proceeding from which Damages may result, as such expenses are incurred; provided, however, that the indemnity agreement contained in this Section 2.8(a) shall not apply to
amounts paid in settlement of any such claim or proceeding if such settlement is effected without the consent of the Company, which consent shall not be unreasonably withheld, nor shall the Company be liable for any Damages to the extent that they
arise out of or are based upon actions or omissions made in reliance upon and in conformity with written information furnished by or on behalf of any such Holder, underwriter, controlling Person, or other aforementioned Person expressly for use in
connection with such registration. 
 (b) To the extent permitted by law, each selling Holder, severally and not jointly, will
indemnify and hold harmless the Company, and each of its directors, each of its officers who has signed the registration statement, each Person (if any), who controls the Company within the meaning of the Securities Act, legal counsel and
accountants for the Company, any underwriter (as defined in the Securities Act), any other Holder selling securities in such registration statement, and any controlling Person of any such underwriter or other Holder, against any Damages, in each
case only to the extent that such Damages arise out of or are based upon actions or omissions made in reliance upon and in conformity with written information furnished by or on behalf of such selling Holder expressly for use in connection with such
registration; and each such selling Holder will pay to the Company and each other aforementioned Person any legal or other expenses reasonably incurred thereby in connection with investigating or defending any claim or proceeding from which Damages
may result, as such expenses are incurred; provided, however, that the indemnity agreement contained in this Section 2.8(b) shall not apply to amounts paid in settlement of any such claim or proceeding if such settlement is effected
without the consent of the Holder, which consent shall not be unreasonably withheld; and provided further that in no event shall the aggregate amounts payable by any Holder by way of indemnity or contribution under Section 2.8(b) and
2.8(d) exceed the proceeds from the offering received by such Holder (net of any Selling Expenses paid by such Holder), except in the case of fraud or willful misconduct by such Holder. 

  
 10. 

 (c) Promptly after receipt by an indemnified party under this Section 2.8 of
notice of the commencement of any action (including any governmental action) for which a party may be entitled to indemnification hereunder, such indemnified party will, if a claim in respect thereof is to be made against any indemnifying party
under this Section 2.8, give the indemnifying party notice of the commencement thereof. The indemnifying party shall have the right to participate in such action and, to the extent the indemnifying party so desires, participate jointly with any
other indemnifying party to which notice has been given, and to assume the defense thereof with counsel mutually satisfactory to the parties; provided, however, that an indemnified party (together with all other indemnified parties that may
be represented without conflict by one counsel) shall have the right to retain one separate counsel, with the fees and expenses to be paid by the indemnifying party, if representation of such indemnified party by the counsel retained by the
indemnifying party would be inappropriate due to actual or potential differing interests between such indemnified party and any other party represented by such counsel in such action. The failure to give notice to the indemnifying party within a
reasonable time of the commencement of any such action shall relieve such indemnifying party of any liability to the indemnified party under this Section 2.8, to the extent that such failure materially prejudices the indemnifying party’s
ability to defend such action. The failure to give notice to the indemnifying party will not relieve it of any liability that it may have to any indemnified party otherwise than under this Section 2.8. 

(d) To provide for just and equitable contribution to joint liability under the Securities Act in any case in which either:
(i) any party otherwise entitled to indemnification hereunder makes a claim for indemnification pursuant to this Section 2.8 but it is judicially determined (by the entry of a final judgment or decree by a court of competent jurisdiction
and the expiration of time to appeal or the denial of the last right of appeal) that such indemnification may not be enforced in such case, notwithstanding the fact that this Section 2.8 provides for indemnification in such case, or
(ii) contribution under the Securities Act may be required on the part of any party hereto for which indemnification is provided under this Section 2.8, then, and in each such case, such parties will contribute to the aggregate losses,
claims, damages, liabilities, or expenses to which they may be subject (after contribution from others) in such proportion as is appropriate to reflect the relative fault of each of the indemnifying party and the indemnified party in connection with
the statements, omissions, or other actions that resulted in such loss, claim, damage, liability, or expense, as well as to reflect any other relevant equitable considerations. The relative fault of the indemnifying party and of the indemnified
party shall be determined by reference to, among other things, whether the untrue or allegedly untrue statement of a material fact, or the omission or alleged omission of a material fact, relates to information supplied by the indemnifying party or
by the indemnified party and the parties’ relative intent, knowledge, access to information, and opportunity to correct or prevent such statement or omission; provided, however, that, in any such case (x) no Holder will be required
to contribute any amount in excess of the public offering price of all such Registrable Securities offered and sold by such Holder pursuant to such registration statement, and (y) no Person guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) will be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation; and provided further that in no event shall a Holder’s liability pursuant to
this Section 2.8(d), when combined with the amounts paid or payable by such Holder pursuant to Section 2.8(b), exceed the proceeds from the offering received by such Holder (net of any Selling Expenses paid by such Holder), except in the
case of willful misconduct or fraud by such Holder. 
 (e) Notwithstanding the foregoing, to the extent that the provisions on
indemnification and contribution contained in the underwriting agreement entered into in connection with the underwritten public offering are in conflict with the foregoing provisions, the provisions in the underwriting agreement shall control. 

(f) Unless otherwise superseded by an underwriting agreement entered into in connection with the underwritten public offering, the
obligations of the Company and Holders under this Section 2.8 shall survive the completion of any offering of Registrable Securities in a registration under this Section 2, and otherwise shall survive the termination of this Agreement.

  
 11. 

 2.9 Reports Under Exchange Act. With a view to making available to the Holders
the benefits of SEC Rule 144 and any other rule or regulation of the SEC that may at any time permit a Holder to sell securities of the Company to the public without registration or pursuant to a registration on Form
S-3, the Company shall: 
 (a) make and keep available adequate current public information,
as those terms are understood and defined in SEC Rule 144, at all times after the effective date of the registration statement filed by the Company for the IPO; 

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

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

2.10 Limitations on Subsequent Registration Rights. From and after the date of this Agreement, the Company shall not, without the
prior written consent of the Holders of a majority of the Registrable Securities then outstanding, enter into any agreement with any holder or prospective holder of any securities of the Company that would (i) provide to such holder or
prospective holder the right to include securities in any registration on other than either a pro rata basis with respect to the Registrable Securities or on a subordinate basis after all Holders have had the opportunity to include in the
registration and offering all shares of Registrable Securities that they wish to so include or (ii) allow such holder or prospective holder to include such securities in any registration unless, under the terms of such agreement, such holder or
prospective holder may include such securities in any such registration only to the extent that the inclusion of such securities will not reduce the number of the Registrable Securities of the Holders that are included; provided that this
limitation shall not apply to Registrable Securities acquired by any additional Investor that becomes a party to this Agreement in accordance with Section 6.9. 

2.11 “Market Stand-off” Agreement. 

(a) Each Holder hereby agrees that it will not, without the prior written consent of the managing underwriter, during the period
commencing on the date of the final prospectus relating to the registration by the Company for its own behalf of shares of its Common Stock or any other equity securities under the Securities Act on a registration statement on Form S-1, and ending on the date specified by the Company or the managing underwriter, as applicable (such period not to exceed 180 days), (i) lend; offer; pledge; sell; contract to sell; sell any option or contract to
purchase; purchase any option or contract to sell; grant any option, right, or warrant to purchase; or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or
exchangeable (directly or indirectly) for Common Stock held immediately before the effective date of the registration statement for the IPO, or (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of
the economic consequences of ownership of such securities, whether any such transaction described in clause (i) or (ii) above is to be settled by delivery of Common Stock or other securities, in cash, or otherwise. The foregoing provisions of
this Section 2.11(a) shall apply only to the IPO and shall not apply to the sale of any shares to an underwriter pursuant to an underwriting agreement or the transfer of any shares to any trust for the direct or indirect benefit of the Holder
or the Immediate Family Member of the Holder, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for
value, and shall be applicable to the Holders only if all officers, directors, and stockholders individually owning more than 1% of the Company’s outstanding Common Stock (after giving effect to conversion into Common Stock of all outstanding
Preferred Stock), are subject to the same restrictions. The underwriters in connection with such registration are intended third-party beneficiaries of this Section 2.11(a) and shall have the right, power
and authority to enforce the provisions hereof as though they were a party hereto. Each Holder further agrees to execute such agreements as may be reasonably requested by the underwriters in connection with any such registration that are consistent
with this Section 2.11(a) or that are necessary to give further effect thereto. Any discretionary waiver or termination of the restrictions of any or all of such agreements by the Company or the underwriters shall apply pro rata to all Company
stockholders that are subject to such agreements, based on the number of shares subject to such agreements. 

  
 12. 

 (b) In connection with a SPAC Transaction, each Holder agrees to enter into an
agreement with the SPAC and/or the Company to not transfer the Public Shares received by such Holder in connection with the SPAC Transaction (excluding (i) any Public Shares purchased in a private placement, or received in exchange for or upon
conversion of securities issued in a private placement, that is connected to or conditioned on the SPAC Transaction and (ii) any securities acquired following the consummation of the SPAC Transaction) pursuant to terms substantially similar to
the terms set forth in Section 2.11(a). 
 2.12 Restrictions on Transfer. 

(a) The Preferred Stock and the Registrable Securities shall not be sold, pledged, or otherwise transferred, and the Company shall not
recognize and shall issue stop-transfer instructions to its transfer agent with respect to any such sale, pledge, or transfer, except upon the conditions specified in this Agreement, which conditions are intended to ensure compliance with the
provisions of the Securities Act. A transferring Holder will cause any proposed purchaser, pledgee, or transferee of the Preferred Stock and the Registrable Securities held by such Holder to agree to take and hold such securities subject to the
provisions and upon the conditions specified in this Agreement. Notwithstanding the foregoing, the Company shall not require any transferee of shares pursuant to an effective registration statement or, following the IPO, SEC Rule 144, in each case,
to be bound by the terms of this Agreement. 
 (b) Each certificate, instrument, or book entry representing (i) the Preferred
Stock, (ii) the Registrable Securities, and (iii) any other securities issued in respect of the securities referenced in clauses (i) and (ii), upon any stock split, stock dividend, recapitalization, merger, consolidation, or similar
event, shall (unless otherwise permitted by the provisions of Section 2.12(c)) be notated with a legend substantially in the following form: 

THE SECURITIES REPRESENTED HEREBY HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.
SUCH SHARES MAY NOT BE SOLD, PLEDGED, OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR A VALID EXEMPTION FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SAID ACT. THE SECURITIES REPRESENTED HEREBY MAY BE TRANSFERRED ONLY IN
ACCORDANCE WITH THE TERMS OF AN AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY. 

  
 13. 

 The Holders consent to the Company making a notation in its records and giving instructions
to any transfer agent of the Restricted Securities in order to implement the restrictions on transfer set forth in this Section 2.12. 

(c) The holder of such Restricted Securities, by acceptance of ownership thereof, agrees to comply in all respects with the provisions
of this Section 2. Before any proposed sale, pledge, or transfer of any Restricted Securities, unless there is in effect a registration statement under the Securities Act covering the proposed transaction or following the IPO, the transfer is
made pursuant to SEC Rule 144, the Holder thereof shall give notice to the Company of such Holder’s intention to effect such sale, pledge, or transfer. Each such notice shall describe the manner and circumstances of the proposed sale, pledge,
or transfer in sufficient detail and, if reasonably requested by the Company, shall be accompanied at such Holder’s expense by either (i) a written opinion of legal counsel who shall, and whose legal opinion shall, be reasonably
satisfactory to the Company, addressed to the Company, to the effect that the proposed transaction may be effected without registration under the Securities Act; (ii) a “no action” letter from the SEC to the effect that the proposed
sale, pledge, or transfer of such Restricted Securities without registration will not result in a recommendation by the staff of the SEC that action be taken with respect thereto; or (iii) any other evidence reasonably satisfactory to counsel
to the Company to the effect that the proposed sale, pledge, or transfer of the Restricted Securities may be effected without registration under the Securities Act, whereupon the Holder of such Restricted Securities shall be entitled to sell,
pledge, or transfer such Restricted Securities in accordance with the terms of the notice given by the Holder to the Company. The Company will not require such a notice, legal opinion or “no action” letter (x) in any transaction in
compliance with SEC Rule 144; or (y) in any transaction in which such Holder distributes Restricted Securities to an Affiliate of such Holder for no consideration; provided that, with respect to transfers under the foregoing clause (y),
each transferee agrees in writing to be subject to the terms of this Section 2.12. Each certificate, instrument, or book entry representing the Restricted Securities transferred as above provided shall be notated with, except if such transfer
is made pursuant to SEC Rule 144, the appropriate restrictive legend set forth in Section 2.12(b), except that such certificate instrument, or book entry shall not be notated with such restrictive legend if, in the opinion of counsel for such
Holder and the Company, such legend is not required in order to establish compliance with any provisions of the Securities Act. 
 2.13
Termination of Registration Rights. The right of any Holder to request registration or inclusion of Registrable Securities in any registration pursuant to Sections 2.1 or 2.2 shall terminate upon the earliest to occur of: 

(a) the closing of a Deemed Liquidation Event or a Qualified SPAC Transaction if such Holder’s Registrable Securities are
registered for purposes of the Securities Act following such SPAC Transaction; 
 (b) such time after consummation of the IPO or SPAC
Transaction as SEC Rule 144 or another similar exemption under the Securities Act is available for the sale of all of such Holder’s shares without limitation during a three-month period without registration (and without the requirement for the
Company to be in compliance with the current public information required under subsection (c)(1) of SEC Rule 144); 

  
 14. 

 (c) the fifth anniversary of the IPO or SPAC Transaction. 

3. Information and Observer Rights. 

3.1 Delivery of Financial Statements. The Company shall deliver to each Major Investor, provided that the Board of
Directors has not reasonably determined that such Major Investor is a Competitor: 
 (a) as soon as practicable, but in any event
within 120 days after the end of each fiscal year of the Company (i) a balance sheet as of the end of such year, (ii) statements of income and of cash flows for such year, and (iii) a statement of stockholders’ equity as of the
end of such year, starting with the Company’s 2020 fiscal year, all such financial statements audited and certified by independent public accountants of nationally recognized standing selected by the Company; 

(b) as soon as practicable, but in any event within 45 days after the end of each quarter of each fiscal year of the Company, unaudited
statements of income and cash flows for such fiscal quarter, and an unaudited balance sheet and a statement of stockholders’ equity as of the end of such fiscal quarter, all prepared in accordance with GAAP (except that such financial
statements may (i) be subject to normal year-end audit adjustments; and (ii) not contain all notes thereto that may be required in accordance with GAAP), and a comparison between the actual amounts
as of and for such quarter and the amounts included in the Budget (as defined below) for such quarter, with an explanation of any material differences between such amounts; 

(c) as soon as practicable, but in any event within 45 days after the end of each quarter of each fiscal year of the Company, a
statement showing the number of shares of each class and series of capital stock and securities convertible into or exercisable for shares of capital stock outstanding at the end of the period, the Common Stock issuable upon conversion or exercise
of any outstanding securities convertible or exercisable for Common Stock and the exchange ratio or exercise price applicable thereto, and the number of shares of issued stock options and stock options not yet issued but reserved for issuance, if
any, all in sufficient detail as to permit the Major Investors to calculate their respective percentage equity ownership in the Company; provided, however, that access to an online capitalization management software (such as Carta.com) that contains
the information otherwise required to be delivered under this Section 3.1(c) shall be deemed to satisfy the requirements of this Section 3.1(c), so long as the Company provides prompt notice upon such information becoming available (which
notice requirement shall be deemed satisfied if such online platform makes automatic notifications available to such Major Investor); 

(d) as soon as practicable, but in any event within 30 days of the end of each month, an unaudited income statement and statement of
cash flows for such month, and an unaudited balance sheet and statement of stockholders’ equity as of the end of such month, all prepared in accordance with GAAP (except that such financial statements may (i) be subject to normal year-end audit adjustments and (ii) not contain all notes thereto that may be required in accordance with GAAP); 

(e) as soon as practicable, but in any event 30 days before the end of each fiscal year, a budget and business plan for the next fiscal
year approved by the Board of Directors (collectively, the “Budget”), prepared on a monthly basis and, promptly after prepared, any other budgets or revised budgets prepared by the Company; and 

(f) such other information relating to the financial condition, business, prospects, or corporate affairs of the Company as any Major
Investor may from time to time reasonably request; provided, however, that the Company shall not be obligated under this Section 3.1 to provide information (i) that the Company reasonably determines in good faith to be a trade
secret or confidential information (unless covered by an enforceable confidentiality agreement, in a form acceptable to the Company); or (ii) the disclosure of which would adversely affect the attorney-client privilege between the Company and
its counsel. 

  
 15. 

 If, for any period, the Company has any subsidiary whose accounts are consolidated with
those of the Company, then in respect of such period the financial statements delivered pursuant to the foregoing sections shall be the consolidated and consolidating financial statements of the Company and all such consolidated subsidiaries. 

Notwithstanding anything else in this Section 3.1 to the contrary, the Company may cease providing the information set forth in this
Section 3.1 during the period starting with the date 60 days before the Company’s good-faith estimate of the date of filing of a registration statement if it reasonably concludes it must do so to comply with the SEC rules applicable to
such registration statement and related offering; provided that the Company’s covenants under this Section 3.1 shall be reinstated at such time as the Company is no longer actively employing its commercially reasonable efforts to
cause such registration statement to become effective. 
 3.2 Inspection. The Company shall permit each Major Investor,
provided that the Board of Directors has not reasonably determined that such Major Investor is a Competitor, at such Major Investor’s expense, to visit and inspect the Company’s properties; examine its books of account and records;
and discuss the Company’s affairs, finances, and accounts with its officers, during normal business hours of the Company as may be reasonably requested by the Major Investor; provided, however, that the Company shall not be obligated
pursuant to this Section 3.2 to provide access to any information that (i) it reasonably and in good faith considers to be a trade secret or confidential information (unless covered by an enforceable confidentiality agreement, in form
reasonably acceptable to the Company), (ii) the disclosure of which would adversely affect the attorney-client privilege between the Company and its counsel, or (iii) with respect to NEA, Lonza and Partners, if access to such information could
be withheld from NEA’s, Lonza’s or Partners’ representative, as applicable, pursuant to Section 3.3 had such information been conveyed at a meeting of the Board of Directors or through notices, minutes,
consents, and other materials that the Company provided to its directors. 
 3.3 Observer Rights. 

(a) As long as NEA owns any shares of the Series A Preferred or any Registrable Securities, the Company shall invite a representative
of NEA to attend all meetings of the Board of Directors in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents, and other materials that it provides to its directors;
provided, however, that such representative shall agree to hold in confidence and trust all information so provided; and provided further, that the Company reserves the right to withhold any information and to exclude such
representative from any meeting or portion thereof if (i) access to such information or attendance at such meeting would reasonably be expected to adversely affect the attorney-client privilege between the Company and its counsel or necessary
to protect highly confidential information (unless covered by an enforceable confidentiality agreement, in a form reasonably acceptable to the Company), or (ii) the Board of Directors determines in good faith that such Investor or its
representative is a competitor of the Company, provided that NEA shall not be considered, and neither the Company nor the Board of Directors shall determine that NEA is, a competitor of the Company if NEA does not control or substantially engage in
a business that competes with a material product, process or service in existence or being developed by the Company (of which existence or development the Company shall notify NEA). 

  
 16. 

 (b) As long as Lonza owns any shares of the Series A Preferred or any Registrable
Securities, the Company shall invite a representative of Lonza to attend all meetings of the Board of Directors in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents, and other
materials that it provides to its directors; provided, however, that such representative shall agree to hold in confidence and trust all information so provided; provided further, that the Company reserves the right to withhold any information and
to exclude such representative from a portion of a meeting if (i) access to such information or attendance at such meeting would reasonably be expected to adversely affect the attorney-client privilege between the Company and its counsel or
necessary to protect highly confidential information (unless covered by an enforceable confidentiality agreement, in a form reasonably acceptable to the Company), or (ii) the Board of Directors determines reasonably and in good faith that Lonza
or its representative is a competitor of the Company, provided that Lonza shall not be considered, and neither the Company nor the Board of Directors shall determine that Lonza is, a competitor of the Company if Lonza does not control or
substantially engage in a business that competes with a material product, process or service in existence or being developed by the Company (of which existence or development the Company shall notify Lonza), and further provided that the parties
hereto acknowledge and agree that as of the date of this Agreement, Lonza is not a competitor of the Company and does not control and does not engage in such competitive business referred to in this clause (ii), or (iii) the Board of Directors
in good faith reasonably determines that Lonza has an actual conflict of interest with the Company with respect to such information or the matter being discussed at such portion of a meeting, it being agreed that such a determination by the Board of
Directors may only occur with respect to the following subject matter (in each case to the extent the Board of Directors determines there is such conflict of interest): (a) discussions relating to the procurement or provision of manufacturing
services to the Company; (b) the Company’s discussion or negotiation of licensing, collaboration or other research arrangements with third parties in areas or with partners that are of strategic interest to Lonza (except if such strategic
interest is due to Lonza’s interest in the Company); or (c) matters related to the Exclusive License Agreement dated September 9, 2019 by and between MEEI, the Schepens Eye Research Institute, Inc., Lonza and the Company. 

(c) As long as Partners owns any shares of the Series A Preferred or any Registrable Securities, the Company shall invite a
representative of Partners to attend all meetings of the Board of Directors in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents, and other materials that it provides to its
directors; provided, however, that such representative shall agree to hold in confidence and trust all information so provided; and provided further, that the Company reserves the right to withhold any information and to exclude such
representative from any meeting or portion thereof if (i) access to such information or attendance at such meeting would reasonably be expected to adversely affect the attorney-client privilege between the Company and its counsel or necessary
to protect highly confidential information (unless covered by an enforceable confidentiality agreement, in a form reasonably acceptable to the Company), or (ii) the Board of Directors determines in good faith that such Investor or its
representative is a competitor of the Company, provided that Partners shall not be considered, and neither the Company nor the Board of Directors shall determine that Partners is, a competitor of the Company if Partners does not control or
substantially engage in a business that competes with a material product, process or service in existence or being developed by the Company (of which existence or development the Company shall notify Partners). 

(d) As long as Farallon owns any shares of Series B Preferred Stock or any Registrable Securities, the Company shall invite a
representative of Farallon to attend all meetings of the Board of Directors in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents, and other materials that it provides to its
directors at the same time and in the same manner as provided to such directors; provided, however, that such representative shall agree to hold in confidence and trust all information so provided; and provided further, that the
Company reserves the right to withhold any information and to exclude such representative from any meeting or portion thereof if access to such information or attendance at such meeting would reasonably be expected to adversely affect the
attorney-client privilege between the Company and its counsel or necessary to protect highly confidential information (unless covered by an enforceable confidentiality agreement, in a form reasonably acceptable to the Company). 

  
 17. 

 3.4 Termination of Information and Observer Rights. The
covenants set forth in Section 3.1, Section 3.2, and Section 3.3 shall terminate and be of no further force or effect (i) immediately before the consummation of the IPO, (ii) when the Company first becomes subject to the
periodic reporting requirements of Section 12(g) or 15(d) of the Exchange Act, (iii) upon the closing of a Deemed Liquidation Event, or (iv) upon the consummation of a Qualified SPAC Transaction, whichever event occurs first;
provided, however, that in the event the covenants set forth in Subsection 3.1 terminate upon a Deemed Liquidation Event, if the consideration received by the Investors in such Deemed Liquidation Event includes securities that are not
publicly traded (which, for the avoidance of doubt, shall not include contingent value rights), the Company will use commercially reasonable efforts to ensure that the Major Investors receive financial information from the acquiring company or other
successor to the Company comparable to those set forth in Section 3.1 of this Agreement. 
 3.5 Confidentiality. Each
Investor agrees that such Investor will keep confidential and will not disclose, divulge, or use for any purpose (other than to monitor or make decisions with respect to its investment in the Company) any confidential information obtained from the
Company pursuant to the terms of this Agreement (including notice of the Company’s intention to file a registration statement), unless such confidential information (a) is known or becomes known to the public in general (other than as a
result of a breach of this Section 3.5 by such Investor), (b) is or has been independently developed or conceived by such Investor without use of the Company’s confidential information, or (c) is or has been made known or disclosed to
such Investor by a third party without a breach of any obligation of confidentiality such third party may have to the Company; provided, however, that an Investor may disclose confidential information (i) to its attorneys, accountants,
consultants, and other professionals to the extent necessary to obtain their services in connection with its investment in the Company; (ii) to any prospective purchaser of any Registrable Securities from such Investor, if such prospective
purchaser is required to maintain the confidentiality of such information and is bound by confidentiality obligations consistent with those set forth in this Section 3.5 (other than with respect to the term),
provided that the Board of Directors has not reasonably determined that such prospective purchaser is a Competitor; (iii) to any Affiliate, any existing or prospective partner, member or stockholder, or any wholly owned subsidiary of
such Investor in the ordinary course of business, provided that such Investor informs such Person that such information is confidential and directs such Person to maintain the confidentiality of such information; (iv) as may otherwise be
required by law, regulation, rule, court order or subpoena, provided that (A) if such required disclosure is specifically targeted at information regarding the Company, such Investor promptly notifies the Company of such disclosure, and
(B) such Investor takes reasonable steps to minimize the extent of any such required disclosure; or (v) as requested by a regulator or self-regulatory organization. 

4. Rights to Future Stock Issuances. 

4.1 Right of First Offer. Subject to the terms and conditions of this Section 4.1 and applicable securities laws, if the
Company proposes to offer or sell any New Securities other than shares of Series B Preferred Stock authorized as of the date hereof and sold pursuant to the Purchase Agreement, the Company shall first offer such New Securities to each Major
Investor. A Major Investor shall be entitled to apportion the right of first offer hereby granted to it in such proportions as it deems appropriate, among (i) itself and (ii) its Affiliates; provided that each such Affiliate
(x) is not a Competitor or FOIA Party, unless such party’s purchase of New Securities is otherwise consented to by the Board of Directors, (y) agrees to enter into this Agreement and each of the Amended and Restated Voting Agreement
and Amended and Restated Right of First Refusal and Co-Sale Agreement of even date herewith among the Company, the Investors and the other parties named therein, as an “Investor” under each
such agreement (provided that any Competitor or FOIA Party shall not be entitled to any rights as a Major Investor under Sections 3.1, 3.2 and 4.1 hereof), and (z) agrees to purchase at least such number of New Securities as are
allocable hereunder to the Major Investor holding the fewest number of Preferred Stock and any other Derivative Securities. 

  
 18. 

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

(b) By notification to the Company within 20 days after the Offer Notice is given, each Major Investor may elect to purchase or
otherwise acquire, at the price and on the terms specified in the Offer Notice, up to that portion of such New Securities which equals the proportion that the Common Stock then held by such Major Investor (including, without limitation, all shares
of Common Stock then issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of the Preferred Stock and any other Derivative Securities then held by such Major Investor) bears to the total Common Stock of the Company then
outstanding (assuming full conversion and/or exercise, as applicable, of all Preferred Stock and any other Derivative Securities then outstanding). At the expiration of such 20 day period, the Company shall promptly notify each Major Investor that
elects to purchase or acquire all the shares available to it (each, a “Fully Exercising Investor”) of any other Major Investor’s failure to do likewise. During the 10 day period commencing after the Company has given such
notice, each Fully Exercising Investor may, by giving notice to the Company, elect to purchase or acquire, in addition to the number of shares specified above, up to that portion of the New Securities for which Major Investors were entitled to
subscribe but that were not subscribed for by the Major Investors which is equal to the proportion that the Common Stock issued and held, or issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of Preferred Stock and any
other Derivative Securities then held, by such Fully Exercising Investor bears to the Common Stock issued and held, or issuable (directly or indirectly) upon conversion and/or exercise, as applicable, of the Preferred Stock and any other Derivative
Securities then held, by all Fully Exercising Investors who wish to purchase such unsubscribed shares. The closing of any sale pursuant to this Section 4.1(b) shall occur within the later of 90 days of the date that the Offer Notice is given
and the date of initial sale of New Securities pursuant to Section 4.1(c). 
 (c) If all New Securities referred to in the Offer
Notice are not elected to be purchased or acquired as provided in Section 4.1(b), the Company may, during the 90 day period following the expiration of the periods provided in Section 4.1(b), offer and sell the remaining unsubscribed
portion of such New Securities to any Person or Persons at a price not less than, and upon terms no more favorable to the offeree than, those specified in the Offer Notice. If the Company does not enter into an agreement for the sale of the New
Securities within such period, or if such agreement is not consummated within 30 days of the execution thereof, the right provided hereunder shall be deemed to be revived and such New Securities shall not be offered unless first reoffered to the
Major Investors in accordance with this Section 4.1. 
 (d) The right of first offer in this Section 4.1 shall not be
applicable to (i) Exempted Securities (as defined in the Certificate of Incorporation) or (ii) shares of Common Stock issued in the IPO. 

  
 19. 

 4.2 Termination. The covenants set forth in Section 4.1 shall terminate
and be of no further force or effect (i) immediately before the consummation of the IPO or the Qualified SPAC Transaction, (ii) when the Company first becomes subject to the periodic reporting requirements of Section 12(g) or 15(d) of
the Exchange Act, or (iii) upon the closing of a Deemed Liquidation Event, whichever event occurs first. 
 5. Additional
Covenants. 
 5.1 Insurance. The Company shall use commercially reasonable efforts to cause the existing Directors and
Officers liability insurance to be maintained until such time as the Board of Directors determines that such insurance should be discontinued. The policy will not be cancelable by the Company without prior approval by the Board of Directors.
Notwithstanding any other provision of this Section 5.1 to the contrary, for so long as any Preferred Director is serving on the Board of Directors, the Company shall (a) not cease to maintain a Directors and Officers liability insurance
policy in an amount of at least two million dollars unless approved by each Preferred Director then serving, if any, and (b) no later than thirty (30) calendar days after each expiration or renewal date of such Directors and Officers
liability insurance policy, deliver to each Investor that designated a Preferred Director then serving on the Board of Directors a copy of the new or renewed Directors and Officers liability insurance policy (and evidence of such renewal, if
applicable) and written confirmation that such policy remains in effect. 
 5.2 Employee Agreements. The Company will cause
(i) each Person now or hereafter employed by it or by any subsidiary (or engaged by the Company or any subsidiary as a consultant/independent contractor) to confirm their status as either an at-will
employee or consultant/independent contractor, (ii) enter into a nondisclosure and proprietary rights assignment agreement; and (iii) enter into a one year non-solicitation agreement, substantially
in the form approved by the Board of Directors. In addition, the Company shall not amend, modify, terminate, waive, or otherwise alter, in whole or in part, any of the above referenced agreements or any restricted stock agreement between the Company
and any employee without the consent of a majority of the Preferred Directors then serving, if any. 
 5.3 Employee Stock. All
future purchases or grants of options to purchase the Company’s capital stock, or awards of the Company’s capital stock, to employees or consultants of the Company shall be approved by the Board of Directors, including a majority of the
Preferred Directors then serving, if any. Unless otherwise approved by the Board of Directors, all future employees and consultants of the Company who purchase, receive options to purchase, or receive awards of shares of the Company’s capital
stock after the date hereof shall be required to execute restricted stock or option agreements, as applicable, providing for (i) vesting of shares over a four year period, with the first 25% of such shares vesting following 12 months of
continued employment or service, and the remaining shares vesting in equal monthly installments over the following 36 months, and (ii) a market stand-off provision substantially similar to that in
Section 2.11. Without the prior approval by the Board of Directors, including a majority of the Preferred Directors then serving, if any, the Company shall not amend, modify, terminate, waive or otherwise alter, in whole or in part, any stock
purchase, stock restriction or option agreement with any existing employee or service provider if such amendment would cause it to be inconsistent with this Section 5.3. In addition, unless otherwise approved by the Board of Directors,
including a majority of the Preferred Directors then serving, if any, the Company shall retain (and not waive) a “right of first refusal” on employee transfers until the consummation of the IPO or the Qualified SPAC Transaction and shall
have the right to repurchase unvested shares at cost upon termination of employment of a holder of restricted stock. 

  
 20. 

 5.4 Board Matters. Unless otherwise determined by the vote of a majority of
the directors then in office, the Board of Directors shall meet at least quarterly in accordance with an agreed-upon schedule. The Company shall reimburse the directors for all reasonable out-of-pocket travel expenses incurred (consistent with the Company’s travel policy) in connection with attending meetings or any other activities of the Board of Directors that are requested by the
Company and involve expenses. As soon as reasonably practicable, the Company shall cause to be established and will thereafter maintain, a compensation committee, which shall include at least two of the Preferred Directors then serving, if any, for
the purposes of, among other things, reviewing and determining the compensation of the Company’s executive officers. Each non-employee director shall be entitled in such person’s discretion to be a
member of any committee of the Board of Directors. 
 5.5 Successor Indemnification. If the Company or any of its successors or
assignees consolidates with or merges into any other Person and is not the continuing or surviving corporation or entity of such consolidation or merger, then to the extent necessary, proper provision shall be made so that the successors and
assignees of the Company assume the obligations of the Company with respect to indemnification of members of the Board of Directors as in effect immediately before such transaction, whether such obligations are contained in the Company’s
Bylaws, the Certificate of Incorporation, or elsewhere, as the case may be. 
 5.6 Indemnification Matters. The Company
hereby acknowledges that one (1) or more of the directors nominated to serve on the Board of Directors by one or more of the Investors (each an “Investor Director”) may have certain rights to indemnification, advancement of
expenses and/or insurance provided by one or more of the Investors and certain of their Affiliates (collectively, the “Investor Indemnitors”). The Company hereby agrees (a) that it is the indemnitor of first resort
(i.e., its obligations to any such Investor Director are primary and any obligation of the Investor Indemnitors to advance expenses or to provide indemnification for the same expenses or liabilities incurred by such Investor Director are
secondary), (b) that it shall be required to advance the full amount of expenses incurred by such Investor Director and shall be liable for the full amount of all expenses, judgments, penalties, fines and amounts paid in settlement by or on behalf
of any such Investor Director to the extent legally permitted and as required by the Company’s Certificate of Incorporation or Bylaws of the Company (or any agreement between the Company and such Investor Director), without regard to any rights
such Investor Director may have against the Investor Indemnitors, and, (c) that it irrevocably waives, relinquishes and releases the Investor Indemnitors from any and all claims against the Investor Indemnitors for contribution, subrogation or
any other recovery of any kind in respect thereof. The Company further agrees that no advancement or payment by the Investor Indemnitors on behalf of any such Investor Director with respect to any claim for which such Investor Director has
sought indemnification from the Company shall affect the foregoing and the Investor Indemnitors shall have a right of contribution and/or be subrogated to the extent of such advancement or payment to all of the rights of recovery of such Investor
Director against the Company. The Investor Directors and the Investor Indemnitors are intended third-party beneficiaries of this Section 5.6 and shall have the right, power and authority to enforce the
provisions of this Section 5.6 as though they were a party to this Agreement. 
 5.7 Right to Conduct Activities. The Company
hereby agrees and acknowledges that each of NEA, F-Prime, Atlas, Farallon, EcoR1, RA Capital, TCG and Perceptive (each, a “Fund Investor”) (in each case, together with its respective
Affiliates) is a professional investment organization, and as such each Fund Investor and Lonza review the business plans and related proprietary information of many enterprises, some of which may compete directly or indirectly with the
Company’s business (as currently conducted or as currently propose to be conducted). Nothing in this Agreement shall preclude or in any way restrict the Investors from evaluating or purchasing securities, including publicly traded
securities, of a particular enterprise, or investing in any particular enterprise whether or not such enterprise has products or services which compete with those of the Company; and the Company hereby agrees that, to the extent permitted under
applicable law, each Fund Investor and Lonza (and their respective Affiliates) shall not be liable to the Company for any claim arising out of, or based upon, (i) the investment by such Fund Investor or Lonza, respectively (or their respective
Affiliates), in any entity competitive with the Company, or (ii) actions taken by any partner, officer, employee or other representative of such Fund Investor or Lonza, respectively (or their respective Affiliates), to assist any such
competitive company, whether or not such action was taken as a member of the board of directors of such competitive company or otherwise, and whether or not such action has a detrimental effect on the Company; provided, however, that the foregoing
shall not relieve (x) any of the Investors from liability associated with the unauthorized disclosure of the Company’s confidential information obtained pursuant to this Agreement, or (y) any director or officer of the Company from
any liability associated with his or her fiduciary duties to the Company. 

  
 21. 

 5.8 Expenses of Counsel. In the event of a transaction which is a Sale of the Company
(as defined in the Amended and Restated Voting Agreement of even date herewith among the Investors, the Company and the other parties named therein), the reasonable fees and disbursements, not to exceed $50,000, of one counsel for the Major
Investors (“Investor Counsel”), in their capacities as stockholders, shall be borne and paid by the Company. At the outset of considering a transaction which, if consummated would constitute a Sale of the Company, the Company shall
obtain the ability to share with the Investor Counsel (and such counsel’s clients) and shall share the confidential information (including, without limitation, the initial and all subsequent drafts of memoranda of understanding, letters of
intent and other transaction documents and related noncompete, employment, consulting and other compensation agreements and plans) pertaining to and memorializing any of the transactions which, individually or when aggregated with others would
constitute the Sale of the Company. The Company shall be obligated to share (and cause the Company’s counsel and investment bankers to share) such materials when distributed to the Company’s executives and/or any one or more of the other
parties to such transaction(s). In the event that Investor Counsel deems it appropriate, in its reasonable discretion, to enter into a joint defense agreement or other arrangement to enhance the ability of the parties to protect their communications
and other reviewed materials under the attorney client privilege, the Company shall, and shall direct its counsel to, execute and deliver to Investor Counsel and its clients such an agreement in form and substance reasonably acceptable to Investor
Counsel. In the event that one or more of the other party or parties to such transactions require the clients of Investor Counsel to enter into a confidentiality agreement and/or joint defense agreement in order to receive such information, then the
Company shall share whatever information can be shared without entry into such agreement and shall, at the same time, in good faith work expeditiously to enable Investor Counsel and its clients to negotiate and enter into the appropriate
agreement(s) without undue burden to the clients of Investor Counsel. 
 5.9 Harassment Policy. The Company shall maintain in effect
(i) a Code of Conduct governing appropriate workplace behavior and (ii) an Anti-Harassment and Discrimination Policy prohibiting discrimination and harassment at the Company. 

5.10 Cybersecurity. The Company shall continue to (a) identify its sensitive data and information, and restrict access (through
physical and electronic controls) to those individuals who have a need to access it and (b) implement cybersecurity solution(s) (“Cybersecurity Solutions”) designed to protect its technology and systems (including servers,
laptops, desktops, cloud, containers, virtual environments and data centers) and all data contained in such systems. The Company shall use commercially reasonable efforts to ensure that the Cybersecurity Solutions (x) are up-to-date and include industry-standard protections (e.g., antivirus, endpoint detection and response and threat hunting), (y) to the extent determined necessary by the
Company or the Board of Directors, are backed by a breach prevention warranty from the vendor certifying the effectiveness of such solutions, and (z) require the vendors to notify the Company of any security incidents posing a risk to the
Company’s information (regardless of whether information was actually compromised). The Company shall evaluate on a regular basis whether the Cybersecurity Solutions should be updated to ensure continued effectiveness and industry-standard
protections. The Company shall also educate its employees about the proper use and storage of sensitive information, including regular training as determined reasonably necessary by the Company or the Board of Directors. 

  
 22. 

 5.11 FIRPTA Compliance. The Company shall provide prompt notice to each Fund Investor
and NEA Ventures 2019, Limited Partnership (each a “FIRPTA Notice Entity”) following any “determination date” (as defined in Treasury Regulation Section 1.897-2(c)(1)) on which
the Company becomes a United States real property holding corporation. In addition, upon a written request by a FIRPTA Notice Entity, the Company shall provide such FIRPTA Notice Entity with a written statement informing such FIRPTA Notice Entity
whether its interest in the Company constitutes a United States real property interest. The Company’s determination shall comply with the requirements of Treasury Regulation Section 1.897-2(h)(1) or
any successor regulation, and the Company shall provide timely notice to the Internal Revenue Service, in accordance with and to the extent required by Treasury Regulation Section 1.897-2(h)(2) or any
successor regulation, that such statement has been made. The Company’s written statement to a FIRPTA Notice Entity shall be delivered to such FIRPTA Notice Entity within 10 days of its written request therefor. The Company’s obligation to
furnish such written statement shall continue notwithstanding the fact that a class of the Company’s stock may be regularly traded on an established securities market or the fact that there is no Preferred Stock then outstanding. 

5.12 Ultra-Rare Field. Each of Lonza and MEEI agree that the definition of “Ultra-Rare Field” in Section 1.56 of the
Amended and Restated License, Collaboration and Commercialization Agreement by and between such parties, dated as of September 9, 2019, as amended to date, shall not be amended, modified or waived without the prior written consent of the
Company. 
 5.13 Termination of Covenants. The covenants set forth in this Section 5, except for Sections 5.5, 5.6 and 5.8, shall
terminate and be of no further force or effect (i) immediately before the consummation of the IPO, (ii) when the Company first becomes subject to the periodic reporting requirements of Section 12(g) or 15(d) of the Exchange Act,
(iii) upon a Deemed Liquidation Event, or (iv) upon the consummation of a Qualified SPAC Transaction, whichever event occurs first. 

6. Miscellaneous. 

6.1 Successors and Assigns. The rights under this Agreement may be assigned (but only with all related obligations) by a Holder
to a transferee of Registrable Securities that (i) is an Affiliate of a Holder; (ii) is a Holder’s Immediate Family Member or trust for the benefit of an individual Holder or one or more of such Holder’s Immediate Family Members;
or (iii) after such transfer, holds at least 630,000 shares of Registrable Securities (subject to appropriate adjustment for stock splits, stock dividends, combinations, and other recapitalizations); provided, however, that (x) the Company
is, within a reasonable time after such transfer, furnished with written notice of the name and address of such transferee and the Registrable Securities with respect to which such rights are being transferred; and (y) such transferee agrees in
a written instrument delivered to the Company to be bound by and subject to the terms and conditions of this Agreement, including the provisions of Section 2.11. For the purposes of determining the number of shares of Registrable Securities
held by a transferee, the holdings of a transferee (1) that is an Affiliate or stockholder of a Holder; (2) who is a Holder’s Immediate Family Member; or (3) that is a trust for the benefit of an individual Holder or such
Holder’s Immediate Family Member shall be aggregated together and with those of the transferring Holder; provided further that all transferees who would not qualify individually for assignment of rights shall, as a condition to the applicable
transfer, establish a single attorney-in-fact for the purpose of exercising any rights, receiving notices, or taking any action under this Agreement. The terms and
conditions of this Agreement inure to the benefit of and are binding upon the respective successors and permitted assignees of the parties. Nothing in this Agreement, express or implied, is intended to confer upon any party other than the parties
hereto or their respective successors and permitted assignees any rights, remedies, obligations or liabilities under or by reason of this Agreement, except as expressly provided herein. 

  
 23. 

 6.2 Governing Law. This Agreement shall be governed by the internal law of the
State of Delaware, without regard to conflict of law principles that would result in the application of any law other than the law of the State of Delaware. 

6.3 Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all
of which together shall constitute one and the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, the Uniform Electronic
Transactions Act or other applicable law) or other transmission method and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

6.4 Titles and Subtitles. The titles and subtitles used in this Agreement are for convenience only and are not to be considered
in construing or interpreting this Agreement. 
 6.5 Notices. 

(a) All notices and other communications given or made pursuant to this Agreement shall be in writing and shall be deemed effectively
given upon the earlier of actual receipt or (i) personal delivery to the party to be notified; (ii) when sent, if sent by electronic mail or facsimile during the recipient’s normal business hours, and if not sent during normal
business hours, then on the recipient’s next business day; (iii) five days after having been sent by registered or certified mail, return receipt requested, postage prepaid; or (iv) one business day after the business day of deposit
with a nationally recognized overnight courier, freight prepaid, specifying next-day delivery, with written verification of receipt. All communications shall be sent to the respective parties at their
addresses as set forth on Schedule A hereto, or to the principal office of the Company and to the attention of the Chief Legal Officer, in the case of the Company, or to such email address, facsimile number, or address as subsequently
modified by written notice given in accordance with this Section 6.5. If notice is given to the Company, it shall be sent to 43 Foundry Ave, Suite 120, Waltham, Massachusetts 02453, Attention: Robert Aboud, Email: raaboud@affiniatx.com;
and a copy (which shall not constitute notice) shall also be sent to Cooley LLP, 500 Boylston Street, 14th Floor, Boston, MA 02116-3736, Attention: Ryan S. Sansom, Email: rsansom@cooley.com. 

(b) Consent to Electronic Notice. Each Investor consents to the delivery of any stockholder notice pursuant to the Delaware General
Corporation Law (the “DGCL”), as amended or superseded from time to time, by electronic transmission pursuant to Section 232 of the DGCL (or any successor thereto) at the electronic mail address or the facsimile number set
forth below such Investor’s name on the Schedules hereto, as updated from time to time by notice to the Company, or as on the books of the Company. To the extent that any notice given by means of electronic transmission is returned or
undeliverable for any reason, the foregoing consent shall be deemed to have been revoked until a new or corrected electronic mail address has been provided, and such attempted electronic notice shall be ineffective and deemed to not have been given.
Each Investor agrees to promptly notify the Company of any change in such stockholder’s electronic mail address, and that failure to do so shall not affect the foregoing. 

  
 24. 

 6.6 Amendments and Waivers. Any term of this Agreement may be amended,
modified or terminated and the observance of any term of this Agreement may be waived (either generally or in a particular instance, and either retroactively or prospectively) only with the written consent of the Company and the Preferred Majority
(as defined in the Certificate of Incorporation); provided further that the Company may in its sole discretion waive compliance with Section 2.12(c) (and the Company’s failure to object promptly in writing after notification of a
proposed assignment allegedly in violation of Section 2.12(c) shall be deemed to be a waiver); and provided further that any provision hereof may be waived by any waiving party on such party’s own behalf, without the consent of any
other party. Notwithstanding the foregoing: (a) this Agreement may not be amended, modified or terminated and the observance of any term hereof may not be waived with respect to any Investor without the written consent of such Investor, unless
such amendment, modification, termination, or waiver applies to all Investors in the same fashion and does not adversely affect the rights of any Investor in a manner disproportionate to any adverse effect such amendment, modification, termination,
or waiver has on the rights of other parties hereto (it being agreed that a waiver of the provisions of Section 4 with respect to a particular transaction shall be deemed to apply to all Investors in the same fashion if such waiver does so by
it terms, notwithstanding the fact that certain Investors may nonetheless, by agreement with the Company, purchase securities in such transaction; provided that in the event any Major Investor (including its Affiliates) purchases any New
Securities in any issuance of New Securities by the Company following an amendment, modification or waiver of Section 4 or the definition of “Additional Shares of Common Stock” under the Certificate of Incorporation (a
“Participating Investor”), then each other Major Investor shall be given the opportunity, with notice of at least eight (8) business days, to participate in such offering and to purchase the same proportion (up to 100%) of such
Major Investor’s pro rata share of the New Securities being offered by the Company in the relevant transaction as is being purchased by the Participating Investor purchasing the largest proportion of such Participating Investor’s pro rata
share; provided further that each Major Investor’s pro rata participation amount shall in no event exceed the amount such Major Investor would have been entitled to purchase pursuant to Section 4 notwithstanding such waiver;
(b) the definition of “Affiliate” set forth in Section 1.1 and this clause (b) may only be amended with the written consent of F-Prime; (c) Sections 1.6(b), 1.13, 3.3(d) and
5.7 and this clause (c), in each case as it relates to Farallon, may only be amended, modified or waived with the written consent of Farallon; (d) Section 5.11 and this clause (d) may only be amended with the written consent of NEA;
(e) Section 1.6(b) and Section 5.7, in each case as it relates to RA Capital, may only be amended, modified or waived with the written consent of RA Capital; and (f) Schedule A hereto may be amended by the Company from time to
time to add transferees of any Registrable Securities in compliance with the terms of this Agreement without the consent of the other parties, and information regarding any additional Investor who becomes a party to this Agreement in accordance with
Section 6.9. The Company shall give prompt notice of any amendment, modification or termination hereof or waiver hereunder to any party hereto that did not consent in writing to such amendment, modification, termination, or waiver. Any
amendment, modification, termination, or waiver effected in accordance with this Section 6.6 shall be binding on all parties hereto, regardless of whether any such party has consented thereto. No waivers of or exceptions to any term, condition,
or provision of this Agreement, in any one or more instances, shall be deemed to be or construed as a further or continuing waiver of any such term, condition, or provision. 

6.7 Severability. In case any one or more of the provisions contained in this Agreement is for any reason held to be invalid,
illegal or unenforceable in any respect, such invalidity, illegality, or unenforceability shall not affect any other provision of this Agreement, and such invalid, illegal, or unenforceable provision shall be reformed and construed so that it will
be valid, legal, and enforceable to the maximum extent permitted by law. 
 6.8 Aggregation of Stock. All shares of Registrable
Securities held or acquired by Affiliates shall be aggregated together for the purpose of determining the availability of any rights under this Agreement and such Affiliates may apportion such rights as among themselves in any manner they deem
appropriate. 

  
 25. 

 6.9 Additional Investors. Notwithstanding anything to the contrary contained
herein, if the Company issues additional shares of Preferred Stock after the date hereof, any purchaser of such shares of Preferred Stock may become a party to this Agreement by executing and delivering an additional counterpart signature page to
this Agreement, and thereafter shall be deemed an “Investor” for all purposes hereunder. No action or consent by the Investors shall be required for such joinder to this Agreement by such additional Investor, so long as such additional
Investor has agreed in writing to be bound by all of the obligations as an “Investor” hereunder. 
 6.10 Entire Agreement.
This Agreement (including any Schedules and Exhibits hereto) constitutes the full and entire understanding and agreement among the parties with respect to the subject matter hereof, and any other written or oral agreement relating to the subject
matter hereof existing between the parties is expressly canceled. Upon the effectiveness of this Agreement, the Prior Agreement shall be deemed amended and restated and superseded and replaced in its entirety by this Agreement, and shall be of no
further force or effect. 
 6.11 Dispute Resolution. The parties (a) hereby irrevocably and unconditionally submit to the
jurisdiction of the state courts of Delaware and to the jurisdiction of the United States District Court for the District of Delaware for the purpose of any suit, action or other proceeding arising out of or based upon this Agreement, (b) agree
not to commence any suit, action or other proceeding arising out of or based upon this Agreement except in the state courts of Delaware or the United States District Court for the District of Delaware, and (c) hereby waive, and agree not to
assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the above-named courts, that its property is exempt or immune from attachment or
execution, that the suit, action or proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court. 

WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT, THE
OTHER TRANSACTION DOCUMENTS, THE SECURITIES OR THE SUBJECT MATTER HEREOF OR THEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT
RELATE TO THE SUBJECT MATTER OF THIS TRANSACTION, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS BEEN FULLY DISCUSSED BY EACH
OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH PARTY KNOWINGLY AND VOLUNTARILY
WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL. 
 6.12 Delays or Omissions. No delay or omission to exercise
any right, power, or remedy accruing to any party under this Agreement, upon any breach or default of any other party under this Agreement, shall impair any such right, power, or remedy of such nonbreaching or nondefaulting party, nor shall it be
construed to be a waiver of or acquiescence to any such breach or default, or to any similar breach or default thereafter occurring, nor shall any waiver of any single breach or default be deemed a waiver of any other breach or default theretofore
or thereafter occurring. All remedies, whether under this Agreement or by law or otherwise afforded to any party, shall be cumulative and not alternative. 

[Remainder of page intentionally left blank] 

  
 26. 

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	COMPANY: 
	
	AFFINIA THERAPEUTICS INC.
		
	By:	 	 /s/ Rick Modi

		 	Name:	 	Rick Modi
		 	Title:	 	Chief Executive Officer

 Schedule A-1 
  

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR: 
		
	By:	 	 /s/ Rick Modi

		 	Name:	 	Rick Modi

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR: 
		
	By:	 	 /s/ Robert A. Aboud

		 	Name:	 	Robert A. Aboud

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	 NEW ENTERPRISE ASSOCIATES 17, L.P.

BY:  NEA PARTNERS 17, L.P., ITS GENERAL
PARTNER
 BY:  NEA 17 GP, LLC, ITS GENERAL
PARTNER

		
	By:	 	 /s/ Louis Citron

		 	Name:	 	Louis Citron
		 	Title:	 	Director

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	NEA VENTURES 2019, LIMITED PARTNERSHIP
		
	By:	 	 /s/ Louis Citron

		 	Name:	 	Louis Citron
		 	Title:	 	Vice President

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	 F-PRIME CAPITAL PARTNERS
LIFE SCIENCES FUND VI LP
 BY:  F-PRIME CAPITAL PARTNERS LIFE SCIENCES ADVISORS FUND VI LP, ITS GENERAL
PARTNER
 BY:  IMPRESA HOLDINGS LLC,
ITS GENERAL PARTNER

BY:  IMPRESA MANAGEMENT LLC, ITS
MANAGING MEMBER

		
	By:	 	 /s/ Mary Bevelock Pendergast

		 	Name:	 	Mary Bevelock Pendergast
		 	Title:	 	Vice President

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	 ATLAS VENTURE FUND XI, L.P.

BY:  ATLAS VENTURE ASSOCIATES XI, L.P.,
ITS GENERAL PARTNER

BY:  ATLAS VENTURE ASSOCIATES XI, LLC,
ITS GENERAL PARTNER 

		
	By:	 	 /s/ Ommer Chohan

		 	Name:	 	Ommer Chohan
		 	Title:	 	Chief Financial Officer

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	 PARTNERS INNOVATION FUND II, L.P.

BY: Partners Innovation II, LLC, ITS GENERAL PARTNER

		
	By:	 	 /s/ Roger Kitterman

		 	Name:	 	Roger Kitterman
		 	Title:	 	Partner

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	PARTNERS INNOVATION FUND, LLC
		
	By:	 	 /s/ Roger Kitterman

		 	Name:	 	Roger Kitterman
		 	Title:	 	Partner

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	MASSACHUSETTS EYE AND EAR INFIRMARY
		
	By:	 	 /s/ Roger Kitterman

		 	Name:	 	Roger Kitterman
		 	Title:	 	Vice President

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	LONZA HOUSTON, INC.
		
	By:	 	 /s/ Anthony Branciforte

		 	Name:	 	Anthony Branciforte
		 	Title:	 	Vice President

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
		
	By:	 	 /s/ Luc Vandenberghe

		 	Name:	 	Luc Vandenberghe

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
		
	By:	 	 /s/ Sean Nolan

		 	Name:	 	Sean Nolan

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	 ECOR1 CAPITAL FUND, L.P.

  
 By: EcoR1 Capital, LLC, its
General Partner

		
	By:	 	 /s/ Oleg Nodelman

		 	Name:	 	Oleg Nodelman
		 	Title:	 	Manager
	
	 ECOR1 CAPITAL FUND QUALIFIED, L.P. 
  

By: EcoR1 Capital, LLC, its General Partner

		
	By:	 	 /s/ Oleg Nodelman

		 	Name:	 	Oleg Nodelman
		 	Title:	 	Manager
	
	 ECOR1 VENTURE OPPORTUNITY FUND, L.P. 
  
 By: Biotech Opportunity GP,
LLC, its General Partner

		
	By:	 	 /s/ Oleg Nodelman

		 	Name:	 	Oleg Nodelman
		 	Title:	 	Manager

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	ZONE III HEALTHCARE HOLDINGS, LLC
		
	 By: 
	 	 Farallon Capital Management, L.L.C.,

its Manager

		
	By:	 	 /s/ Philip Dreyfuss

		 	Name:	 	Philip Dreyfuss
		 	Title:	 	Authorized Signatory

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

			
	INVESTOR:
	
	RA CAPITAL HEALTHCARE FUND, L.P.
	
	By: RA Capital Healthcare Fund GP, LLC
	Its General Partner
		
	By:	 	 /s/ Rajeev Shah

	Name: Rajeev Shah
	Title:   Manager

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

			
	INVESTOR:
	
	RA CAPITAL NEXUS FUND II, L.P.
	
	By: RA Capital Nexus Fund II GP, LLC
	Its: General Partner
		
	By:	 	 /s/ Rajeev Shah

	Name: Rajeev Shah
	Title: Manager

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTORS:
	
	 OCTAGON INVESTMENTS MASTER FUND LP
  

By: Octagon Capital Advisors, LP
 Its Investment
Manager

		
	By:	 	 /s/ Ting Jia

		 	Name:	 	Ting Jia
		 	Title:	 	Managing Member
	
	 OCTAGON PRIVATE OPPORTUNITIES FUND LP
  

By: Octagon Capital Advisors, LP
 Its Investment
Manager

		
	By:	 	 /s/ Ting Jia

		 	Name:	 	Ting Jia
		 	Title:	 	Managing Member

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTORS:
	
	 CASDIN PRIVATE GROWTH EQUITY FUND, L.P.
  

By: Casdin Private Growth Equity Fund GP, LLC, its General Partner

		
	By:	 	 /s/ Kevin O’Brien

		 	Name:	 	Kevin O’Brien
		 	Title:	 	General Counsel
	
	 CASDIN PARTNERS MASTER FUND, L.P.
  

By: Casdin Partners GP, LLC, its General Partner

		
	By:	 	 /s/ Kevin O’Brien

		 	Name:	 	Kevin O’Brien
		 	Title:	 	General Counsel

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	 TCG CROSSOVER FUND I, L.P.

 
 By: TCG Crossover GP I, LLC

Its General Partner

		
	By:	 	 /s/ Chen Yu

		 	Name:	 	Chen Yu
		 	Title:	 	Managing Member

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

			
	INVESTOR:
	
	GV 2021, L.P.
	By: GV 2021 GP, L.P., its General Partner
	By: GV 2021 GP, L.L.C., its General Partner
		
	By:	 	 /s/ Daphne M. Chang

	Name: Daphne M. Chang
	Title: Authorized Signatory

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of
the date first written above. 
  

					
	INVESTOR:
	
	 PERCEPTIVE LIFE SCIENCES MASTER FUND, LTD.

By: Perceptive Advisors, LLC

		
	By:	 	 /s/ James H. Mannix

		 	Name:	 	James H. Mannix
		 	Title:	 	COO

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	 WOODLINE PARTNERS
 By:
Woodline Partners LP, its Manager

		
	By:	 	 /s/ Matthew Hooker

		 	Name:	 	Matthew Hooker
		 	Title:	 	Managing Member of Woodline Fund GP LLC, its General Partner

 The parties have executed this Amended and Restated Investors’ Rights Agreement as of the date first
written above. 
  

					
	INVESTOR:
	
	AVIDITY MASTER FUND LP
		
	By:	 	 /s/ Michael Gregory

		 	Name:	 	Michael Gregory
		 	Title:	 	Director

  

					
	AVIDITY CAPITAL FUND II LP
		
	By:	 	 /s/ Michael Gregory

		 	Name:	 	Michael Gregory
		 	Title:	 	Director

 SCHEDULE A 

INVESTORSEX-10.6

 Exhibit 10.6 

TDTX, INC. 
 2019 EQUITY
INCENTIVE PLAN 
 ADOPTED BY THE BOARD OF DIRECTORS: November 25, 2019 

APPROVED BY THE STOCKHOLDERS: November 25, 2019 

TERMINATION DATE: November 24, 2029 

1. General. 
 (a)
Eligible Stock Award Recipients. Employees, Directors and Consultants are eligible to receive Stock Awards. 
 (b)
Available Stock Awards. The Plan provides for the grant of the following types of Stock Awards: (i) Incentive Stock Options, (ii) Nonstatutory Stock Options, (iii) Stock Appreciation Rights, (iv) Restricted Stock
Awards, (v) Restricted Stock Unit Awards and (vi) Other Stock Awards. 
 (c) Purpose. The Plan, through the grant of
Stock Awards, is intended to help the Company secure and retain the services of eligible award recipients, provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate and provide a means by which the
eligible recipients may benefit from increases in value of the Common Stock. 
 2. Administration. 

(a) Administration by the Board. The Board will administer the Plan. The Board may delegate administration of the Plan to a Committee or
Committees, as provided in Section 2(c). 
 (b) Powers of the Board. The Board will have the power, subject to, and within the
limitations of, the express provisions of the Plan: 
 (i) To determine (A) who will be granted Stock Awards; (B) when and
how each Stock Award will be granted; (C) what type of Stock Award will be granted; (D) the provisions of each Stock Award (which need not be identical), including when a person will be permitted to exercise or otherwise receive cash or
Common Stock under the Stock Award; (E) the number of shares of Common Stock subject to, or the cash value of, a Stock Award; and (F) the Fair Market Value applicable to a Stock Award. 

(ii) To construe and interpret the Plan and Stock Awards granted under it, and to establish, amend and revoke rules and regulations for
administration of the Plan and Stock Awards. The Board, in the exercise of these powers, may correct any defect, omission or inconsistency in the Plan or in any Stock Award Agreement, in a manner and to the extent it will deem necessary or expedient
to make the Plan or Stock Award fully effective. 
 (iii) To settle all controversies regarding the Plan and Stock Awards granted
under it. 
 (iv) To accelerate, in whole or in part, the time at which a Stock Award may be exercised or vest (or the time at which
cash or shares of Common Stock may be issued in settlement thereof). 

  
 1. 

 (v) To suspend or terminate the Plan at any time. Except as otherwise provided in the
Plan or a Stock Award Agreement, suspension or termination of the Plan will not impair a Participant’s rights under the Participant’s then-outstanding Stock Award without the Participant’s written consent except as provided in
subsection (viii) below. 
 (vi) To amend the Plan in any respect the Board deems necessary or advisable, including, without
limitation, by adopting amendments relating to Incentive Stock Options and certain nonqualified deferred compensation under Section 409A of the Code and/or bringing the Plan or Stock Awards granted under the Plan into compliance with the
requirements for Incentive Stock Options or ensuring that they are exempt from, or compliant with, the requirements for nonqualified deferred compensation under Section 409A of the Code, subject to the limitations, if any, of applicable law. If
required by applicable law or listing requirements, and except as provided in Section 9(a) relating to Capitalization Adjustments, the Company will seek stockholder approval of any amendment of the Plan that (A) materially increases the
number of shares of Common Stock available for issuance under the Plan, (B) materially expands the class of individuals eligible to receive Stock Awards under the Plan, (C) materially increases the benefits accruing to Participants under
the Plan, (D) materially reduces the price at which shares of Common Stock may be issued or purchased under the Plan, (E) materially extends the term of the Plan, or (F) materially expands the types of Stock Awards available for
issuance under the Plan. Except as otherwise provided in the Plan or a Stock Award Agreement, no amendment of the Plan will materially impair a Participant’s rights under an outstanding Stock Award without the Participant’s written
consent. 
 (vii) To submit any amendment to the Plan for stockholder approval, including, but not limited to, amendments to the Plan
intended to satisfy the requirements of Section 422 of the Code regarding Incentive Stock Options. 
 (viii) To approve forms of
Stock Award Agreements for use under the Plan and to amend the terms of any one or more Stock Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Stock Award Agreement,
subject to any specified limits in the Plan that are not subject to Board discretion; provided however, that a Participant’s rights under any Stock Award will not be impaired by any such amendment unless (A) the Company requests the
consent of the affected Participant, and (B) such Participant consents in writing. Notwithstanding the foregoing, (1) a Participant’s rights will not be deemed to have been impaired by any such amendment if the Board, in its sole
discretion, determines that the amendment, taken as a whole, does not materially impair the Participant’s rights, and (2) subject to the limitations of applicable law, if any, the Board may amend the terms of any one or more Stock Awards
without the affected Participant’s consent (A) to maintain the qualified status of the Stock Award as an Incentive Stock Option under Section 422 of the Code; (B) to change the terms of an Incentive Stock Option, if such change
results in impairment of the Stock Award solely because it impairs the qualified status of the Stock Award as an Incentive Stock Option under Section 422 of the Code; (C) to clarify the manner of exemption from, or to bring the Stock Award
into compliance with, Section 409A of the Code; or (D) to comply with other applicable laws. 
 (ix) Generally, to exercise
such powers and to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Stock Awards. 

(x) To adopt such procedures and sub-plans as are necessary or appropriate to permit
participation in the Plan by Employees, Directors or Consultants who are foreign nationals or employed outside the United States (provided that Board approval will not be necessary for immaterial modifications to the Plan or any Stock Award
Agreement that are required for compliance with the laws of the relevant foreign jurisdiction). 

  
 2. 

 (xi) To effect, with the consent of any adversely affected Participant, (A) the
reduction of the exercise, purchase or strike price of any outstanding Stock Award; (B) the cancellation of any outstanding Stock Award and the grant in substitution therefor of a new (1) Option or SAR, (2) Restricted Stock Award,
(3) Restricted Stock Unit Award, (4) Other Stock Award, (5) cash and/or (6) other valuable consideration determined by the Board, in its sole discretion, with any such substituted award (x) covering the same or a different
number of shares of Common Stock as the cancelled Stock Award and (y) granted under the Plan or another equity or compensatory plan of the Company; or (C) any other action that is treated as a repricing under generally accepted accounting
principles. 
 (c) Delegation to Committee. The Board may delegate some or all of the administration of the Plan to a Committee or
Committees. If administration of the Plan is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the
power to delegate to a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or subcommittee, as applicable). Any
delegation of administrative powers will be reflected in resolutions, not inconsistent with the provisions of the Plan, adopted from time to time by the Board or Committee (as applicable). The Board may retain the authority to concurrently
administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers previously delegated. 
 (d)
Delegation to an Officer. The Board may delegate to one or more Officers the authority to do one or both of the following: (i) designate Employees who are not Officers to be recipients of Options and SARs (and, to the extent
permitted by applicable law, other Stock Awards) and, to the extent permitted by applicable law, the terms of such Stock Awards, and (ii) determine the number of shares of Common Stock to be subject to such Stock Awards granted to such
Employees; provided, however, that the Board resolutions regarding such delegation will specify the total number of shares of Common Stock that may be subject to the Stock Awards granted by such Officer and that such Officer may not grant a
Stock Award to himself or herself. Any such Stock Awards will be granted on the form of Stock Award Agreement most recently approved for use by the Committee or the Board, unless otherwise provided in the resolutions approving the delegation
authority. The Board may not delegate authority to an Officer who is acting solely in the capacity of an Officer (and not also as a Director) to determine the Fair Market Value pursuant to Section 13(t) below.  

(e) Effect of Board’s Decision. All determinations, interpretations and constructions made by the Board in
good faith will not be subject to review by any person and will be final, binding and conclusive on all persons. 
 3. Shares Subject to the Plan.

 (a) Share Reserve. 

(i) Subject to Section 9(a) relating to Capitalization Adjustments, the aggregate number of shares of Common Stock that may be
issued pursuant to Stock Awards from and after the Effective Date will not exceed 120,000 shares (the “Share Reserve”). 

  
 3. 

 (ii) For clarity, the Share Reserve in this Section 3(a) is a limitation on the
number of shares of Common Stock that may be issued pursuant to the Plan. Accordingly, this Section 3(a) does not limit the granting of Stock Awards except as provided in Section 7(a). 

(b) Reversion of Shares to the Share Reserve. If a Stock Award or any portion thereof (i) expires or otherwise terminates
without all of the shares covered by such Stock Award having been issued or (ii) is settled in cash (i.e., the Participant receives cash rather than stock), such expiration, termination or settlement will not reduce (or otherwise offset)
the number of shares of Common Stock that may be available for issuance under the Plan. If any shares of Common Stock issued pursuant to a Stock Award are forfeited back to or repurchased by the Company because of the failure to meet a contingency
or condition required to vest such shares in the Participant, then the shares that are forfeited or repurchased will revert to and again become available for issuance under the Plan. Any shares reacquired by the Company in satisfaction of tax
withholding obligations on a Stock Award or as consideration for the exercise or purchase price of a Stock Award will again become available for issuance under the Plan. 

(c) Incentive Stock Option Limit. Subject to the Share Reserve and Section 9(a) relating to Capitalization
Adjustments, the aggregate maximum number of shares of Common Stock that may be issued pursuant to the exercise of Incentive Stock Options will be a number of shares of Common Stock equal to three multiplied by the Share Reserve. 

(d) Source of Shares. The stock issuable under the Plan will be shares of authorized but unissued or reacquired Common Stock, including
shares repurchased by the Company on the open market or otherwise. 
 4. Eligibility. 

(a) Eligibility for Specific Stock Awards. Incentive Stock Options may be granted only to employees of the Company or a “parent
corporation” or “subsidiary corporation” thereof (as such terms are defined in Sections 424(e) and 424(f) of the Code). Stock Awards other than Incentive Stock Options may be granted to Employees, Directors and Consultants;
provided, however, that Stock Awards may not be granted to Employees, Directors and Consultants who are providing Continuous Service only to any “parent” of the Company, as such term is defined in Rule 405, unless (i) the
stock underlying such Stock Awards is treated as “service recipient stock” under Section 409A of the Code (for example, because the Stock Awards are granted pursuant to a corporate transaction such as a spin off transaction), (ii) the
Company, in consultation with its legal counsel, has determined that such Stock Awards are otherwise exempt from Section 409A of the Code, or (iii) the Company, in consultation with its legal counsel, has determined that such Stock Awards
comply with the distribution requirements of Section 409A of the Code. 
 (b) Ten Percent Stockholders. A Ten Percent
Stockholder will not be granted an Incentive Stock Option unless the exercise price of such Option is at least 110% of the Fair Market Value on the date of grant and the Option is not exercisable after the expiration of five years from the date
of grant. 
 (c) Consultants.    A Consultant will not be eligible for the grant of a Stock Award
if, at the time of grant, either the offer or sale of the Company’s securities to such Consultant is not exempt under Rule 701 because of the nature of the services that the Consultant is providing to the Company, because the Consultant is
not a natural person, or because of any other provision of Rule 701, unless the Company determines that such grant need not comply with the requirements of Rule 701 and will satisfy another exemption under the Securities Act as well as
comply with the securities laws of all other relevant jurisdictions. 

  
 4. 

 5. Provisions Relating to Options and Stock Appreciation Rights. 

Each Option or SAR will be in such form and will contain such terms and conditions as the Board deems appropriate. All Options will be
separately designated Incentive Stock Options or Nonstatutory Stock Options at the time of grant, and, if certificates are issued, a separate certificate or certificates will be issued for shares of Common Stock purchased on exercise of each type of
Option. If an Option is not specifically designated as an Incentive Stock Option, or if an Option is designated as an Incentive Stock Option but some portion or all of the Option fails to qualify as an Incentive Stock Option under the applicable
rules, then the Option (or portion thereof) will be a Nonstatutory Stock Option. The provisions of separate Options or SARs need not be identical; provided, however, that each Stock Award Agreement will conform to (through incorporation of
provisions hereof by reference in the applicable Stock Award Agreement or otherwise) the substance of each of the following provisions: 

(a) Term. Subject to the provisions of Section 4(b) regarding Ten Percent Stockholders, no Option or SAR will be exercisable after
the expiration of 10 years from the date of its grant or such shorter period specified in the Stock Award Agreement. 
 (b) Exercise
Price. Subject to the provisions of Section 4(b) regarding Ten Percent Stockholders, the exercise or strike price of each Option or SAR will be not less than 100% of the Fair Market Value of the Common Stock subject to the Option or SAR on
the date the Stock Award is granted. Notwithstanding the foregoing, an Option or SAR may be granted with an exercise or strike price lower than 100% of the Fair Market Value of the Common Stock subject to the Stock Award if such Stock Award is
granted pursuant to an assumption of or substitution for another option or stock appreciation right pursuant to a Corporate Transaction and in a manner consistent with the provisions of Section 409A of the Code and, if applicable,
Section 424(a) of the Code. Each SAR will be denominated in shares of Common Stock equivalents. 
 (c) Purchase Price for
Options. The purchase price of Common Stock acquired pursuant to the exercise of an Option may be paid, to the extent permitted by applicable law and as determined by the Board in its sole discretion, by any combination of the methods of payment
set forth below. The Board will have the authority to grant Options that do not permit all of the following methods of payment (or otherwise restrict the ability to use certain methods) and to grant Options that require the consent of the Company to
use a particular method of payment. The permitted methods of payment are as follows: 
 (i) by cash, check, bank draft, electronic
funds transfer or money order payable to the Company; 
 (ii) subject to Company and/or Board consent at the time of exercise and
provided that at the time of exercise the Common Stock is publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of
cash (or check) by the Company or the receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day
sale”, or “sell to cover”; 
 (iii) subject to Company and/or Board consent at the time of exercise and provided that
at the time of exercise the Common Stock is publicly traded, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock that are owned free and clear of any liens, claims, encumbrances or security
interests, and that are valued at Fair Market Value on the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company and/or the Board, at the time 

  
 5. 

 
Participant exercises their Option, will include delivery to the Company of Participant’s attestation of ownership of such shares of Common Stock in a form approved by the Company.
Participant may not exercise their option by delivery to the Company of Common Stock if doing so would violate the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock; 

(iv) subject to Company and/or Board consent at the time of exercise, and provided that the Option is a Nonstatutory Stock Option, by a
“net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of the Option by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate
exercise price plus, to the extent permitted by the Company and/or Board at the time of exercise, the aggregate withholding obligations in respect of the Option exercise; provided, further that Participant must pay any remaining balance of the
aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock will no longer be subject to the Option and will not be exercisable thereafter to the extent that
(A) shares issuable upon exercise are used to pay the exercise price pursuant to the “net exercise,” (B) shares are delivered to the Participant as a result of such exercise, and (C) shares are withheld to satisfy tax withholding
obligations; 
 (v) according to a deferred payment or similar arrangement with the Optionholder; provided, however, that
interest will compound at least annually and will be charged at the minimum rate of interest necessary to avoid (A) the imputation of interest income to the Company and compensation income to the Optionholder under any applicable provisions of
the Code, and (B) the classification of the Option as a liability for financial accounting purposes; or 
 (vi) in any other form
of legal consideration that may be acceptable to the Board. 
 (d) Exercise and Payment of a SAR. To exercise any outstanding
SAR, the Participant must provide written notice of exercise to the Company in compliance with the provisions of the Stock Appreciation Right Agreement evidencing such SAR. The appreciation distribution payable on the exercise of a SAR will be not
greater than an amount equal to the excess of (A) the aggregate Fair Market Value (on the date of the exercise of the SAR) of a number of shares of Common Stock equal to the number of Common Stock equivalents in which the Participant is vested
under such SAR, and with respect to which the Participant is exercising the SAR on such date, over (B) the aggregate strike price of the number of Common Stock equivalents with respect to which the Participant is exercising the SAR on such
date. The appreciation distribution may be paid in Common Stock, in cash, in any combination of the two or in any other form of consideration, as determined by the Board and contained in the Stock Award Agreement evidencing such SAR. 

(e) Transferability of Options and SARs. The Board may, in its sole discretion, impose such limitations on the transferability of
Options and SARs as the Board will determine. In the absence of such a determination by the Board to the contrary, the following restrictions on the transferability of Options and SARs will apply: 

(i) Restrictions on Transfer. An Option or SAR will not be transferable except by will or by the laws of descent and distribution (or
pursuant to subsections (ii) and (iii) below), and will be exercisable during the lifetime of the Participant only by the Participant. The Board may permit transfer of the Option or SAR in a manner that is not prohibited by applicable tax and
securities laws. Except as explicitly provided in the Plan, neither an Option nor a SAR may be transferred for consideration. 

  
 6. 

 (ii) Domestic Relations Orders. Subject to the approval of the Board or a duly
authorized Officer, an Option or SAR may be transferred pursuant to the terms of a domestic relations order, official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation 1.421-1(b)(2). If an Option is an Incentive Stock Option, such Option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(iii) Beneficiary Designation. Subject to the approval of the Board or a duly authorized Officer, a Participant may, by delivering
written notice to the Company, in a form approved by the Company (or the designated broker), designate a third party who, upon the death of the Participant, will thereafter be entitled to exercise the Option or SAR and receive the Common Stock or
other consideration resulting from such exercise. In the absence of such a designation, upon the death of the Participant, the executor or administrator of the Participant’s estate will be entitled to exercise the Option or SAR and receive the
Common Stock or other consideration resulting from such exercise. However, the Company may prohibit designation of a beneficiary at any time, including due to any conclusion by the Company that such designation would be inconsistent with the
provisions of applicable laws. 
 (f) Vesting Generally. The total number of shares of Common Stock subject to an Option or SAR
may vest and therefore become exercisable in periodic installments that may or may not be equal. The Option or SAR may be subject to such other terms and conditions on the time or times when it may or may not be exercised (which may be based on the
satisfaction of performance goals or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options or SARs may vary. The provisions of this Section 5(f) are subject to any Option or SAR provisions governing the
minimum number of shares of Common Stock as to which an Option or SAR may be exercised. 
 (g) Termination of Continuous Service.
Except as otherwise provided in the applicable Stock Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates (other than for Cause and other than upon the Participant’s
death or Disability), the Participant may exercise his or her Option or SAR (to the extent that the Participant was entitled to exercise such Stock Award as of the date of termination of Continuous Service) within the period of time ending on the
earlier of (i) the date three months following the termination of the Participant’s Continuous Service (or such longer or shorter period specified in the applicable Stock Award Agreement, which period will not be less than
30 days if necessary to comply with applicable laws unless such termination is for Cause) and (ii) the expiration of the term of the Option or SAR as set forth in the Stock Award Agreement. If, after termination of Continuous Service, the
Participant does not exercise his or her Option or SAR (as applicable) within the applicable time frame, the Option or SAR will terminate. 

(h) Extension of Termination Date. If the exercise of an Option or SAR following the termination of the Participant’s
Continuous Service (other than for Cause and other than upon the Participant’s death or Disability) would be prohibited at any time solely because the issuance of shares of Common Stock would violate the registration requirements under the
Securities Act, then the Option or SAR will terminate on the earlier of (i) the expiration of a total period of time (that need not be consecutive) equal to the applicable post-termination exercise period after the termination of the
Participant’s Continuous Service during which the exercise of the Option or SAR would not be in violation of such registration requirements, and (ii) the expiration of the term of the Option or SAR as set forth in the applicable Stock
Award Agreement. In addition, unless otherwise provided in a Participant’s Stock Award Agreement, if the sale of any Common Stock received upon exercise of an Option or SAR following the termination of the Participant’s Continuous Service
(other than for Cause) would violate the Company’s insider trading policy, then the Option or SAR will terminate on the earlier of (i) the expiration of the period of time (that need not be consecutive) equal to the applicable
post-termination exercise period after the termination of the Participant’s Continuous Service during which the sale of the Common Stock received upon exercise of the Option or SAR would not be in violation of the Company’s insider trading
policy, and (ii) the expiration of the term of the Option or SAR as set forth in the applicable Stock Award Agreement. 

  
 7. 

 (i) Disability of Participant. Except as otherwise provided in the applicable
Stock Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates as a result of the Participant’s Disability, the Participant may exercise his or her Option or SAR (to the
extent that the Participant was entitled to exercise such Option or SAR as of the date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date 12 months following such termination of
Continuous Service (or such longer or shorter period specified in the Stock Award Agreement, which period will not be less than six months if necessary to comply with applicable laws unless such termination is for Cause), and (ii) the
expiration of the term of the Option or SAR as set forth in the Stock Award Agreement. If, after termination of Continuous Service, the Participant does not exercise his or her Option or SAR within the applicable time frame, the Option or SAR (as
applicable) will terminate. 
 (j) Death of Participant. Except as otherwise provided in the applicable Stock Award Agreement or other
agreement between the Participant and the Company, if (i) a Participant’s Continuous Service terminates as a result of the Participant’s death, or (ii) the Participant dies within the period (if any) specified in the Stock Award
Agreement for exercisability after the termination of the Participant’s Continuous Service (for a reason other than death), then the Option or SAR may be exercised (to the extent the Participant was entitled to exercise such Option or SAR as of
the date of death) by the Participant’s estate, by a person who acquired the right to exercise the Option or SAR by bequest or inheritance or by a person designated to exercise the Option or SAR upon the Participant’s death, but only
within the period ending on the earlier of (i) the date 18 months following the date of death (or such longer or shorter period specified in the Stock Award Agreement, which period will not be less than six months if necessary to
comply with applicable laws unless such termination is for Cause), and (ii) the expiration of the term of such Option or SAR as set forth in the Stock Award Agreement. If, after the Participant’s death, the Option or SAR is not exercised
within the applicable time frame, the Option or SAR (as applicable) will terminate. 
 (k) Termination for Cause. Except as
explicitly provided otherwise in a Participant’s Stock Award Agreement or other individual written agreement between the Company or any Affiliate and the Participant, if a Participant’s Continuous Service is terminated for Cause, the
Option or SAR will terminate immediately upon such Participant’s termination of Continuous Service, and the Participant will be prohibited from exercising his or her Option or SAR (whether vested or unvested) from and after the date of such
termination of Continuous Service. 
 (l) Non-Exempt Employees. If an Option or SAR is granted
to an Employee who is a non-exempt employee for purposes of the Fair Labor Standards Act of 1938, as amended, the Option or SAR will not be first exercisable for any shares of Common Stock until at least six
months following the date of grant of the Option or SAR (although the Stock Award may vest prior to such date). Consistent with the provisions of the Worker Economic Opportunity Act, (i) if such
non-exempt Employee dies or suffers a Disability, (ii) upon a Corporate Transaction in which such Option or SAR is not assumed, continued, or substituted, (iii) upon a Change in Control, or
(iv) upon the Participant’s retirement (as such term may be defined in the Participant’s Stock Award Agreement, in another agreement between the Participant and the Company, or, if no such definition, in accordance with the
Company’s then current employment policies and guidelines), the vested portion of any Options and SARs may be exercised earlier than six months following the date of grant. The foregoing provision is intended to operate so that any income
derived by a non-exempt employee in connection with the exercise or vesting of an Option or SAR will be exempt 

  
 8. 

 
from his or her regular rate of pay. To the extent permitted and/or required for compliance with the Worker Economic Opportunity Act to ensure that any income derived by a non-exempt employee in connection with the exercise, vesting or issuance of any shares under any other Stock Award will be exempt from the employee’s regular rate of pay, the provisions of this
Section 5(l) will apply to all Stock Awards and are hereby incorporated by reference into such Stock Award Agreements. 
 (m) Early
Exercise of Options. An Option may, but need not, include a provision whereby the Optionholder may elect at any time before the Optionholder’s Continuous Service terminates to exercise the Option as to any part or all of the shares of
Common Stock subject to the Option prior to the full vesting of the Option. Subject to the “Repurchase Limitation” in Section 8(l), any unvested shares of Common Stock so purchased may be subject to a repurchase right in favor of
the Company or to any other restriction the Board determines to be appropriate. Provided that the “Repurchase Limitation” in Section 8(l) is not violated, the Company will not be required to exercise its repurchase right until at
least six months (or such longer or shorter period of time required to avoid classification of the Option as a liability for financial accounting purposes) have elapsed following exercise of the Option unless the Board otherwise specifically
provides in the Option Agreement. 
 (n) Right of Repurchase. Subject to the “Repurchase Limitation” in
Section 8(l), the Option or SAR may include a provision whereby the Company may elect to repurchase all or any part of the vested shares of Common Stock acquired by the Participant pursuant to the exercise of the Option or SAR. 

(o) Right of First Refusal. The Option or SAR may include a provision whereby the Company may elect to exercise a right of first
refusal following receipt of notice from the Participant of the intent to transfer all or any part of the shares of Common Stock received upon the exercise of the Option or SAR. Such right of first refusal will be subject to the
“Repurchase Limitation” in Section 8(l). Except as expressly provided in this Section 5(o) or in the Stock Award Agreement, such right of first refusal will otherwise comply with any applicable provisions of the bylaws of
the Company. 
 6. Provisions of Stock Awards Other than Options and SARs. 

(a) Restricted Stock Awards. Each Restricted Stock Award Agreement will be in such form and will contain such terms and
conditions as the Board will deem appropriate. To the extent consistent with the Company’s bylaws, at the Board’s election, shares of Common Stock underlying a Restricted Stock Award may be (i) held in book entry form subject to the
Company’s instructions until any restrictions relating to the Restricted Stock Award lapse; or (ii) evidenced by a certificate, which certificate will be held in such form and manner as determined by the Board. The terms and conditions of
Restricted Stock Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Award Agreements need not be identical. Each Restricted Stock Award Agreement will conform to (through incorporation of the
provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions: 
 (i) Consideration.
A Restricted Stock Award may be awarded in consideration for (A) cash, check, bank draft or money order payable to the Company, (B) past services to the Company or an Affiliate, or (C) any other form of legal consideration
(including future services) that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 
 (ii)
Vesting. Subject to the “Repurchase Limitation” in Section 8(l), shares of Common Stock awarded under the Restricted Stock Award Agreement may be subject to forfeiture to the Company in accordance with a vesting schedule to
be determined by the Board. 

  
 9. 

 (iii) Termination of Participant’s Continuous Service. If a Participant’s
Continuous Service terminates, the Company may receive through a forfeiture condition or a repurchase right, any or all of the shares of Common Stock held by the Participant that have not vested as of the date of termination of Continuous Service
under the terms of the Restricted Stock Award Agreement. 
 (iv) Transferability. Rights to acquire shares of Common Stock under the
Restricted Stock Award Agreement will be transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Stock Award Agreement, as the Board will determine in its sole discretion, so long as Common Stock
awarded under the Restricted Stock Award Agreement remains subject to the terms of the Restricted Stock Award Agreement. 
 (v)
Dividends. A Restricted Stock Award Agreement may provide that any dividends paid on Restricted Stock will be subject to the same vesting and forfeiture restrictions as apply to the shares subject to the Restricted Stock Award to which
they relate. 
 (b) Restricted Stock Unit Awards. Each Restricted Stock Unit Award Agreement will be in such form and will
contain such terms and conditions as the will Board deem appropriate. The terms and conditions of Restricted Stock Unit Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Unit Award Agreements
need not be identical. Each Restricted Stock Unit Award Agreement will conform to (through incorporation of the provisions hereof by reference in the Agreement or otherwise) the substance of each of the following provisions: 

(i) Consideration. At the time of grant of a Restricted Stock Unit Award, the Board will determine the consideration, if any, to
be paid by the Participant upon delivery of each share of Common Stock subject to the Restricted Stock Unit Award. The consideration to be paid (if any) by the Participant for each share of Common Stock subject to a Restricted Stock Unit Award may
be paid in any form of legal consideration that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 

(ii) Vesting. At the time of the grant of a Restricted Stock Unit Award, the Board may impose such restrictions on or
conditions to the vesting of the Restricted Stock Unit Award as it, in its sole discretion, deems appropriate. 
 (iii)
Payment. A Restricted Stock Unit Award may be settled by the delivery of shares of Common Stock, their cash equivalent, any combination thereof or in any other form of consideration, as determined by the Board and contained in the
Restricted Stock Unit Award Agreement. 
 (iv) Additional Restrictions. At the time of the grant of a Restricted Stock
Unit Award, the Board, as it deems appropriate, may impose such restrictions or conditions that delay the delivery of the shares of Common Stock (or their cash equivalent) subject to a Restricted Stock Unit Award to a time after the vesting of such
Restricted Stock Unit Award. 
 (v) Dividend Equivalents. Dividend equivalents may be credited in respect of shares of
Common Stock covered by a Restricted Stock Unit Award, as determined by the Board and contained in the Restricted Stock Unit Award Agreement. At the sole discretion of the Board, such dividend equivalents may be converted into additional shares of
Common Stock covered by the Restricted Stock Unit Award in such manner as determined by the Board. Any additional shares covered by the Restricted Stock Unit Award credited by reason of such dividend equivalents will be subject to all of the same
terms and conditions of the underlying Restricted Stock Unit Award Agreement to which they relate. 

  
 10. 

 (vi) Termination of Participant’s Continuous Service.
Except as otherwise provided in the applicable Restricted Stock Unit Award Agreement, such portion of the Restricted Stock Unit Award that has not vested will be forfeited upon the Participant’s termination of Continuous Service. 

 (vii) Compliance with Section 409A of the Code.    Notwithstanding anything to the contrary
set forth herein, any Restricted Stock Unit Award granted under the Plan that is not exempt from the requirements of Section 409A of the Code will contain such provisions so that such Restricted Stock Unit Award will comply with the
requirements of Section 409A of the Code. Such restrictions, if any, will be determined by the Board and contained in the Restricted Stock Unit Award Agreement evidencing such Restricted Stock Unit Award. For example, such restrictions may
include, without limitation, a requirement that any Common Stock that is to be issued in a year following the year in which the Restricted Stock Unit Award vests must be issued in accordance with a fixed
pre-determined schedule. 
 (c) Other Stock Awards. Other forms of Stock Awards valued
in whole or in part by reference to, or otherwise based on, Common Stock, including the appreciation in value thereof (e.g., options or stock rights with an exercise price or strike price less than 100% of the Fair Market Value of the Common Stock
at the time of grant) may be granted either alone or in addition to Stock Awards provided for under Section 5 and the preceding provisions of this Section 6. Subject to the provisions of the Plan, the Board will have sole and complete
authority to determine the persons to whom and the time or times at which such Other Stock Awards will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted pursuant to such Other Stock Awards and all other
terms and conditions of such Other Stock Awards. 
 7. Covenants of the Company. 

(a) Availability of Shares. The Company will keep available at all times the number of shares of Common Stock reasonably required
to satisfy then-outstanding Stock Awards. 
 (b) Securities Law Compliance. The Company will seek to obtain from each regulatory
commission or agency having jurisdiction over the Plan such authority as may be required to grant Stock Awards and to issue and sell shares of Common Stock upon exercise of the Stock Awards; provided, however, that this undertaking will not
require the Company to register under the Securities Act the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any such Stock Award. If, after reasonable efforts and at a reasonable cost, the Company is unable to obtain from
any such regulatory commission or agency the authority that counsel for the Company deems necessary for the lawful issuance and sale of Common Stock under the Plan, the Company will be relieved from any liability for failure to issue and sell Common
Stock upon exercise of such Stock Awards unless and until such authority is obtained. A Participant will not be eligible for the grant of a Stock Award or the subsequent issuance of cash or Common Stock pursuant to the Stock Award if such grant or
issuance would be in violation of any applicable securities law. 
 (c) No Obligation to Notify or Minimize Taxes. The Company
will have no duty or obligation to any Participant to advise such holder as to the time or manner of exercising such Stock Award. Furthermore, the Company will have no duty or obligation to warn or otherwise advise such holder of a pending
termination or expiration of a Stock Award or a possible period in which the Stock Award may not be exercised. The Company has no duty or obligation to minimize the tax consequences of a Stock Award to the holder of such Stock Award. 

  
 11. 

 8. Miscellaneous. 

(a) Use of Proceeds from Sales of Common Stock. Proceeds from the sale of shares of Common Stock pursuant to Stock Awards will
constitute general funds of the Company. 
 (b) Corporate Action Constituting Grant of Stock Awards. Corporate action constituting a
grant by the Company of a Stock Award to any Participant will be deemed completed as of the date of such corporate action, unless otherwise determined by the Board, regardless of when the instrument, certificate, or letter evidencing the Stock Award
is communicated to, or actually received or accepted by, the Participant. In the event that the corporate records (e.g., Board consents, resolutions or minutes) documenting the corporate action constituting the grant contain terms (e.g., exercise
price, vesting schedule or number of shares) that are inconsistent with those in the Stock Award Agreement or related grant documents as a result of a clerical error in the papering of the Stock Award Agreement or related grant documents, the
corporate records will control and the Participant will have no legally binding right to the incorrect term in the Stock Award Agreement or related grant documents. 

(c) Stockholder Rights. No Participant will be deemed to be the holder of, or to have any of the rights of a holder with respect to, any
shares of Common Stock subject to a Stock Award unless and until (i) such Participant has satisfied all requirements for exercise of, or the issuance of shares of Common Stock under, the Stock Award pursuant to its terms, and (ii) the
issuance of the Common Stock subject to the Stock Award has been entered into the books and records of the Company. 
 (d) No Employment
or Other Service Rights. Nothing in the Plan, any Stock Award Agreement or any other instrument executed thereunder or in connection with any Stock Award granted pursuant thereto will confer upon any Participant any right to continue to serve
the Company or an Affiliate in the capacity in effect at the time the Stock Award was granted or will affect the right of the Company or an Affiliate to terminate (i) the employment of an Employee with or without notice and with or without
cause, (ii) the service of a Consultant pursuant to the terms of such Consultant’s agreement with the Company or an Affiliate, or (iii) the service of a Director pursuant to the bylaws of the Company or an Affiliate, and any
applicable provisions of the corporate law of the state in which the Company or the Affiliate is incorporated, as the case may be. 
 (e)
Change in Time Commitment. In the event a Participant’s regular level of time commitment in the performance of his or her services for the Company and any Affiliates is reduced (for example, and without limitation, if the Participant is an
Employee of the Company and the Employee has a change in status from a full-time Employee to a part-time Employee or takes an extended leave of absence) after the date of grant of any Stock Award to the Participant, the Board has the right in its
sole discretion to (x) make a corresponding reduction in the number of shares subject to any portion of such Stock Award that is scheduled to vest or become payable after the date of such change in time commitment, and (y) in lieu of or in
combination with such a reduction, extend the vesting or payment schedule applicable to such Stock Award. In the event of any such reduction, the Participant will have no right with respect to any portion of the Stock Award that is so reduced or
extended. 
 (f) Incentive Stock Option Limitations. To the extent that the aggregate Fair Market Value (determined at the time of
grant) of Common Stock with respect to which Incentive Stock Options are exercisable for the first time by any Optionholder during any calendar year (under all plans of the Company and any Affiliates) exceeds $100,000 (or such other limit
established in the Code) or otherwise does not comply with the rules governing Incentive Stock Options, the Options or portions thereof that exceed such limit (according to the order in which they were granted) or otherwise do not comply with such
rules will be treated as Nonstatutory Stock Options, notwithstanding any contrary provision of the applicable Option Agreement(s). 

  
 12. 

 (g) Investment Assurances. The Company may require a Participant, as a condition of
exercising or acquiring Common Stock under any Stock Award, (i) to give written assurances satisfactory to the Company as to the Participant’s knowledge and experience in financial and business matters and/or to employ a purchaser
representative reasonably satisfactory to the Company who is knowledgeable and experienced in financial and business matters and that the Participant is capable of evaluating, alone or together with the purchaser representative, the merits and risks
of exercising the Stock Award; and (ii) to give written assurances satisfactory to the Company stating that the Participant is acquiring Common Stock subject to the Stock Award for the Participant’s own account and not with any present
intention of selling or otherwise distributing the Common Stock. The foregoing requirements, and any assurances given pursuant to such requirements, will be inoperative if (A) the issuance of the shares upon the exercise or acquisition of
Common Stock under the Stock Award has been registered under a then currently effective registration statement under the Securities Act, or (B) as to any particular requirement, a determination is made by counsel for the Company that such
requirement need not be met in the circumstances under the then applicable securities laws. The Company may, upon advice of counsel to the Company, place legends on stock certificates issued under the Plan as such counsel deems necessary or
appropriate in order to comply with applicable securities laws, including, but not limited to, legends restricting the transfer of the Common Stock. 

(h) Withholding Obligations. Unless prohibited by the terms of a Stock Award Agreement, the Company may, in its sole discretion,
satisfy any federal, state or local tax withholding obligation relating to a Stock Award by any of the following means or by a combination of such means: (i) causing the Participant to tender a cash payment; (ii) withholding shares of
Common Stock from the shares of Common Stock issued or otherwise issuable to the Participant in connection with the Stock Award; provided, however, that no shares of Common Stock are withheld with a value exceeding the maximum amount of tax
required to be withheld by law (or such lesser amount as may be necessary to avoid classification of the Stock Award as a liability for financial accounting purposes); (iii) withholding cash from a Stock Award settled in cash;
(iv) withholding payment from any amounts otherwise payable to the Participant; or (v) by such other method as may be set forth in the Stock Award Agreement. 

(i) Electronic Delivery. Any reference herein to a “written” agreement or document will include any agreement or document
delivered electronically or posted on the Company’s intranet (or other shared electronic medium controlled by the Company to which the Participant has access). 

(j) Deferrals. To the extent permitted by applicable law, the Board, in its sole discretion, may determine that the delivery of Common
Stock or the payment of cash, upon the exercise, vesting or settlement of all or a portion of any Stock Award may be deferred and may establish programs and procedures for deferral elections to be made by Participants. Deferrals by Participants will
be made in accordance with Section 409A of the Code. Consistent with Section 409A of the Code, the Board may provide for distributions while a Participant is still an employee or otherwise providing services to the Company. The Board is
authorized to make deferrals of Stock Awards and determine when, and in what annual percentages, Participants may receive payments, including lump sum payments, following the Participant’s termination of Continuous Service, and implement such
other terms and conditions consistent with the provisions of the Plan and in accordance with applicable law. 

  
 13. 

 (k) Compliance with Section 409A of the Code. To the extent
that the Board determines that any Stock Award granted hereunder is subject to Section 409A of the Code, the Stock Award Agreement evidencing such Stock Award will incorporate the terms and conditions necessary to avoid the consequences
specified in Section 409A(a)(1) of the Code. To the extent applicable, the Plan and Stock Award Agreements will be interpreted in accordance with Section 409A of the Code. Notwithstanding anything to the contrary in the Plan (and unless
the Stock Award Agreement specifically provides otherwise), if the shares of Common Stock are publicly traded, and if a Participant holding a Stock Award that constitutes “deferred compensation” under Section 409A of the Code is a
“specified employee” for purposes of Section 409A of the Code, no distribution or payment of any amount that is due because of a “separation from service” (as defined in Section 409A of the Code without regard to
alternative definitions thereunder) will be issued or paid before the date that is six months following the date of such Participant’s “separation from service” (as defined in Section 409A of the Code without regard to
alternative definitions thereunder) or, if earlier, the date of the Participant’s death, unless such distribution or payment can be made in a manner that complies with Section 409A of the Code, and any amounts so deferred will be paid in a
lump sum on the day after such six month period elapses, with the balance paid thereafter on the original schedule. 
 (l)
Repurchase Limitation. The terms of any repurchase right will be specified in the Stock Award Agreement. The repurchase price for vested shares of Common Stock will be the Fair Market Value of the shares of Common Stock on the date of
repurchase. The repurchase price for unvested shares of Common Stock will be the lower of (i) the Fair Market Value of the shares of Common Stock on the date of repurchase or (ii) their original purchase price. However, the Company will
not exercise its repurchase right until at least six months (or such longer or shorter period of time necessary to avoid classification of the Stock Award as a liability for financial accounting purposes) have elapsed following delivery of
shares of Common Stock subject to the Stock Award, unless otherwise specifically provided by the Board. 
 9. Adjustments upon Changes in Common Stock;
Other Corporate Events. 
 (a) Capitalization Adjustments. In the event of a Capitalization Adjustment, the Board will
appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of securities that may be issued pursuant to the exercise
of Incentive Stock Options pursuant to Section 3(c), and (iii) the class(es) and number of securities and price per share of stock subject to outstanding Stock Awards. The Board will make such adjustments, and its determination will be
final, binding and conclusive. 
 (b) Dissolution or Liquidation. Except as otherwise provided in the Stock Award Agreement, in the
event of a dissolution or liquidation of the Company, all outstanding Stock Awards (other than Stock Awards consisting of vested and outstanding shares of Common Stock not subject to a forfeiture condition or the Company’s right of repurchase)
will terminate immediately prior to the completion of such dissolution or liquidation, and the shares of Common Stock subject to the Company’s repurchase rights or subject to a forfeiture condition may be repurchased or reacquired by the
Company notwithstanding the fact that the holder of such Stock Award is providing Continuous Service, provided, however, that the Board may, in its sole discretion, cause some or all Stock Awards to become fully vested, exercisable and/or no
longer subject to repurchase or forfeiture (to the extent such Stock Awards have not previously expired or terminated) before the dissolution or liquidation is completed but contingent on its completion. 

(c) Corporate Transaction. The following provisions will apply to Stock Awards in the event of a Corporate Transaction unless
otherwise provided in the instrument evidencing the Stock Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board at the time of grant of a Stock Award. In the
event of a Corporate Transaction, then, notwithstanding any other provision of the Plan, the Board may take one or more of the following actions with respect to Stock Awards, contingent upon the closing or completion of the Corporate Transaction:

 (i) arrange for the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent
company) to assume or continue the Stock Award or to substitute a similar stock award for the Stock Award (including, but not limited to, an award to acquire the same consideration paid to the stockholders of the Company pursuant to the Corporate
Transaction); 

  
 14. 

 (ii) arrange for the assignment of any reacquisition or repurchase rights held by the
Company in respect of Common Stock issued pursuant to the Stock Award to the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company); 

(iii) accelerate the vesting, in whole or in part, of the Stock Award (and, if applicable, the time at which the Stock Award may be
exercised) to a date prior to the effective time of such Corporate Transaction as the Board determines (or, if the Board does not determine such a date, to the date that is five days prior to the effective date of the Corporate Transaction),
with such Stock Award terminating if not exercised (if applicable) at or prior to the effective time of the Corporate Transaction; provided, however, that the Board may require Participants to complete and deliver to the Company a notice of
exercise before the effective date of a Corporate Transaction, which exercise is contingent upon the effectiveness of such Corporate Transaction; 

(iv) arrange for the lapse, in whole or in part, of any reacquisition or repurchase rights held by the Company with respect to the Stock
Award; 
 (v) cancel or arrange for the cancellation of the Stock Award, to the extent not vested or not exercised prior to the
effective time of the Corporate Transaction, in exchange for such cash consideration (including no consideration) as the Board, in its sole discretion, may consider appropriate; and 

(vi) make a payment, in such form as may be determined by the Board equal to the excess, if any, of (A) the value of the property
the Participant would have received upon the exercise of the Stock Award immediately prior to the effective time of the Corporate Transaction, over (B) any exercise price payable by such holder in connection with such exercise. For clarity,
this payment may be zero ($0) if the value of the property is equal to or less than the exercise price. Payments under this provision may be delayed to the same extent that payment of consideration to the holders of the Company’s Common Stock
in connection with the Corporate Transaction is delayed as a result of escrows, earn outs, holdbacks or any other contingencies. 
 The Board need not take
the same action or actions with respect to all Stock Awards or portions thereof or with respect to all Participants. The Board may take different actions with respect to the vested and unvested portions of a Stock Award. 

(d) Change in Control. A Stock Award may be subject to additional acceleration of vesting and exercisability upon or after a Change in
Control as may be provided in the Stock Award Agreement for such Stock Award or as may be provided in any other written agreement between the Company or any Affiliate and the Participant, but in the absence of such provision, no such acceleration
will occur. 

  
 15. 

 10. Plan Term; Earlier Termination or Suspension of the Plan. 

(a) Plan Term. The Board may suspend or terminate the Plan at any time. Unless terminated sooner by the Board, the Plan will
automatically terminate on the day before the 10th anniversary of the earlier of (i) the date the Plan is adopted by the Board, or (ii) the date the Plan is approved by the stockholders of the Company. No Stock Awards may be granted under
the Plan while the Plan is suspended or after it is terminated. 
 (b) No Impairment of Rights. Suspension or termination of the Plan
will not impair rights and obligations under any Stock Award granted while the Plan is in effect except with the written consent of the affected Participant or as otherwise permitted in the Plan. 

11. Effective Date of Plan. 
 This
Plan will become effective on the Effective Date.  
 12. Choice of Law. 

The laws of the State of Delaware will govern all questions concerning the construction, validity and interpretation of this Plan,
without regard to that state’s conflict of laws rules. 
 13. Definitions. As used in the Plan, the following definitions will apply to
the capitalized terms indicated below: 
 (a) “Affiliate” means, at the time of determination, any
“parent” or “majority-owned subsidiary” of the Company, as such terms are defined in Rule 405. The Board will have the authority to determine the time or times at which “parent” or “majority-owned
subsidiary” status is determined within the foregoing definition. 
 (b) “Board” means the Board of
Directors of the Company. 
 (c) “Capitalization Adjustment” means any change that is made in, or other events
that occur with respect to, the Common Stock subject to the Plan or subject to any Stock Award after the Effective Date without the receipt of consideration by the Company through merger, consolidation, reorganization, recapitalization,
reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, reverse stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure, or any similar
equity restructuring transaction, as that term is used in Statement of Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the conversion of any convertible
securities of the Company will not be treated as a Capitalization Adjustment. 
 (d) “Cause”
will have the meaning ascribed to such term in any written agreement between the Participant and the Company defining such term and, in the absence of such agreement, such term means, with respect to a Participant, the occurrence of any of
the following events: (i) such Participant’s commission of any felony or any crime involving fraud, dishonesty or moral turpitude under the laws of the United States or any state thereof; (ii) such Participant’s attempted
commission of, or participation in, a fraud or act of dishonesty against the Company, or any of its employees or directors; (iii) such Participant’s intentional, material violation of any contract or agreement between the Participant and
the Company, the Company’s employment policies, or of any statutory or other duty owed to the Company; (iv) such Participant’s unauthorized use or disclosure of the Company’s confidential information or trade

  
 16. 

 
secrets; or (v) such Participant’s gross misconduct. The determination that a termination of the Participant’s Continuous Service is either for Cause or without Cause will be made
by the Company, in its sole discretion. Any determination by the Company that the Continuous Service of a Participant was terminated with or without Cause for the purposes of outstanding Stock Awards held by such Participant will have no effect upon
any determination of the rights or obligations of the Company or such Participant for any other purpose. 
 (e) “Change in
Control” means the occurrence, in a single transaction or in a series of related transactions, of any one or more of the following events: 

(i) any Exchange Act Person becomes the Owner, directly or indirectly, of securities of the Company representing more than 50% of the
combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or similar transaction. Notwithstanding the foregoing, a Change in Control will not be deemed to occur (A) on account of the
acquisition of securities of the Company directly from the Company, (B) on account of the acquisition of securities of the Company by an investor, any affiliate thereof or any other Exchange Act Person that acquires the Company’s
securities in a transaction or series of related transactions the primary purpose of which is to obtain financing for the Company through the issuance of equity securities or (C) solely because the level of Ownership held by any Exchange Act
Person (the “Subject Person”) exceeds the designated percentage threshold of the outstanding voting securities as a result of a repurchase or other acquisition of voting securities by the
Company reducing the number of shares outstanding, provided that if a Change in Control would occur (but for the operation of this sentence) as a result of the acquisition of voting securities by the Company, and after such share acquisition, the
Subject Person becomes the Owner of any additional voting securities that, assuming the repurchase or other acquisition had not occurred, increases the percentage of the then outstanding voting securities Owned by the Subject Person over the
designated percentage threshold, then a Change in Control will be deemed to occur;  
 (ii) there is consummated a merger,
consolidation or similar transaction involving (directly or indirectly) the Company and, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do not Own,
directly or indirectly, either (A) outstanding voting securities representing more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more than 50% of the
combined outstanding voting power of the parent of the surviving Entity in such merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the Company
immediately prior to such transaction; or 
 (iii) there is consummated a sale, lease, exclusive license or other disposition of all
or substantially all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries to an Entity, more
than 50% of the combined voting power of the voting securities of which are Owned by stockholders of the Company in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such
sale, lease, license or other disposition. 
 Notwithstanding the foregoing definition or any other provision of this Plan, (A) the term Change in
Control will not include a sale of assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company, (B) the definition of Change in Control (or any analogous term) in an individual written
agreement between the Company or any Affiliate and the Participant will supersede the 

  
 17. 

 
foregoing definition with respect to Stock Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set forth in such an
individual written agreement, the definition set forth herein will apply, and (C) if at any time the Company’s Certificate of Incorporation provides definitions of various analogous transactions that would be deemed a liquidation event for
the Company, then such definition will apply as if it were the definition set forth herein except as is otherwise expressly provided in an individual written agreement between the Company or any Affiliate and the Participant. 

(f) “Code” means the Internal Revenue Code of 1986, as amended, including any applicable regulations and
guidance thereunder. 
 (g) “Committee” means a committee of one or more Directors to whom authority has been
delegated by the Board in accordance with Section 2(c). 
 (h) “Common Stock” means the common stock of
the Company. 
 (i) “Company” means TDTx, Inc., a Delaware corporation. 

(j) “Consultant” means any person, including an advisor, who is (i) engaged by the Company or an Affiliate
to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors of an Affiliate and is compensated for such services. However, service solely as a Director, or payment of a
fee for such service, will not cause a Director to be considered a “Consultant” for purposes of the Plan.  
 (k)
“Continuous Service” means that the Participant’s service with the Company or an Affiliate, whether as an Employee, Director or Consultant, is not interrupted or terminated. A change in the capacity in which the
Participant renders service to the Company or an Affiliate as an Employee, Director or Consultant or a change in the Entity for which the Participant renders such service, provided that there is no interruption or termination of the
Participant’s service with the Company or an Affiliate, will not terminate a Participant’s Continuous Service; provided, however, that if the Entity for which a Participant is rendering services ceases to qualify as an Affiliate, as
determined by the Board in its sole discretion, such Participant’s Continuous Service will be considered to have terminated on the date such Entity ceases to qualify as an Affiliate. For example, a change in status from an Employee of the
Company to a Consultant of an Affiliate or to a Director will not constitute an interruption of Continuous Service. To the extent permitted by law, the Board or the chief executive officer of the Company, in that party’s sole discretion, may
determine whether Continuous Service will be considered interrupted in the case of (i) any leave of absence approved by the Board or chief executive officer, including sick leave, military leave or any other personal leave, or
(ii) transfers between the Company, an Affiliate, or their successors. Notwithstanding the foregoing, a leave of absence will be treated as Continuous Service for purposes of vesting in a Stock Award only to such extent as may be provided in
the Company’s leave of absence policy, in the written terms of any leave of absence agreement or policy applicable to the Participant, or as otherwise required by law. 

(l) “Corporate Transaction” means the consummation, in a single transaction or in a series of related
transactions, of any one or more of the following events: 
 (i) a sale or other disposition of all or substantially all, as
determined by the Board in its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 

  
 18. 

 (ii) a sale or other disposition of more than 50% of the outstanding securities of
the Company; 
 (iii) a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or

 (iv) a merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares of
Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of securities, cash or
otherwise. 
 (m) “Director” means a member of the Board. 

(n) “Disability” means, with respect to a Participant, the inability of such Participant to engage in any
substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or can be expected to last for a continuous period of not less than
twelve (12) months as provided in Sections 22(e)(3) and 409A(a)(2)(c)(i) of the Code, and will be determined by the Board on the basis of such medical evidence as the Board deems warranted under the circumstances. 

(o) “Effective Date” means the effective date of this Plan, which is the earlier of (i) the date that this
Plan is first approved by the Company’s stockholders, and (ii) the date this Plan is adopted by the Board. 
 (p)
“Employee” means any person employed by the Company or an Affiliate. However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be considered an “Employee” for
purposes of the Plan. 
 (q) “Entity” means a corporation, partnership, limited liability company or other
entity. 
 (r) “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and
regulations promulgated thereunder. 
 (s) “Exchange Act Person” means any natural person,
Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” will not include (i) the Company or any Subsidiary of the Company, (ii) any employee
benefit plan of the Company or any Subsidiary of the Company or any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any Subsidiary of the Company, (iii) an underwriter temporarily holding
securities pursuant to a registered public offering of such securities, (iv) an Entity Owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their Ownership of stock of the Company; or
(v) any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act) that, as of the Effective Date, is the Owner, directly or indirectly, of securities of the Company representing more
than 50% of the combined voting power of the Company’s then outstanding securities. 
 (t) “Fair Market
Value” means, as of any date, the value of the Common Stock determined by the Board in compliance with Section 409A of the Code or, in the case of an Incentive Stock Option, in compliance with Section 422 of the Code. 

  
 19. 

 (u) “Incentive Stock Option” means an option granted pursuant
to Section 5 of the Plan that is intended to be, and that qualifies as, an “incentive stock option” within the meaning of Section 422 of the Code. 

(v) “Nonstatutory Stock Option” means an option granted pursuant to Section 5 of the Plan that does not
qualify as an Incentive Stock Option. 
 (w) “Officer” means any person designated by the Company as an
officer. 
 (x) “Option” means an Incentive Stock Option or a Nonstatutory Stock Option to purchase shares of
Common Stock granted pursuant to the Plan. 
 (y) “Option Agreement” means a written agreement between the
Company and an Optionholder evidencing the terms and conditions of an Option grant. Each Option Agreement will be subject to the terms and conditions of the Plan. 

(z) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if applicable, such
other person who holds an outstanding Option. 
 (aa) “Other Stock Award” means an award based in whole or in
part by reference to the Common Stock which is granted pursuant to the terms and conditions of Section 6(c). 
 (bb)
“Other Stock Award Agreement” means a written agreement between the Company and a holder of an Other Stock Award evidencing the terms and conditions of an Other Stock Award grant. Each Other Stock Award Agreement will be
subject to the terms and conditions of the Plan. 
 (cc) “Own,” “Owned,”
“Owner,” “Ownership” A person or Entity will be deemed to “Own,” to have “Owned,” to be the “Owner” of, or to have acquired “Ownership” of securities if
such person or Entity, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares voting power, which includes the power to vote or to direct the voting, with respect to such securities. 

(dd) “Participant” means a person to whom a Stock Award is granted pursuant to the Plan or, if applicable, such
other person who holds an outstanding Stock Award. 
 (ee) “Plan” means this 2019 Equity Incentive Plan. 

(ff) “Restricted Stock Award” means an award of shares of Common Stock which is granted pursuant to the terms
and conditions of Section 6(a). 
 (gg) “Restricted Stock Award Agreement” means a written agreement
between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a Restricted Stock Award grant. Each Restricted Stock Award Agreement will be subject to the terms and conditions of the Plan. 

(hh) “Restricted Stock Unit Award” means a right to receive shares of Common Stock which is
granted pursuant to the terms and conditions of Section 6(b). 

  
 20. 

 (ii) “Restricted Stock Unit Award Agreement”
means a written agreement between the Company and a holder of a Restricted Stock Unit Award evidencing the terms and conditions of a Restricted Stock Unit Award grant. Each Restricted Stock Unit Award Agreement will be subject to the terms
and conditions of the Plan. 
 (jj) “Rule 405” means Rule 405 promulgated under the Securities Act. 

(kk) “Rule 701” means Rule 701 promulgated under the Securities Act. 

(ll) “Securities Act” means the Securities Act of 1933, as amended. 

(mm) “Stock Appreciation Right” or “SAR” means a right to receive the appreciation on
Common Stock that is granted pursuant to the terms and conditions of Section 5. 
 (nn) “Stock Appreciation Right
Agreement” means a written agreement between the Company and a holder of a Stock Appreciation Right evidencing the terms and conditions of a Stock Appreciation Right grant. Each Stock Appreciation Right Agreement will be subject to the
terms and conditions of the Plan. 
 (oo) “Stock Award” means any right to receive Common Stock granted under
the Plan, including an Incentive Stock Option, a Nonstatutory Stock Option, a Restricted Stock Award, a Restricted Stock Unit Award, a Stock Appreciation Right or any Other Stock Award. 

(pp) “Stock Award Agreement” means a written agreement between the Company and a Participant evidencing the
terms and conditions of a Stock Award grant. Each Stock Award Agreement will be subject to the terms and conditions of the Plan. 
 (qq)
“Subsidiary” means, with respect to the Company, (i) any corporation of which more than 50% of the outstanding capital stock having ordinary voting power to elect a majority of the board of directors of such
corporation (irrespective of whether, at the time, stock of any other class or classes of such corporation will have or might have voting power by reason of the happening of any contingency) is at the time, directly or indirectly, Owned by the
Company, and (ii) any partnership, limited liability company or other entity in which the Company has a direct or indirect interest (whether in the form of voting or participation in profits or capital contribution) of more than 50%. 

(rr) “Ten Percent Stockholder” means a person who Owns (or is deemed to Own pursuant to Section 424(d) of
the Code) stock possessing more than 10% of the total combined voting power of all classes of stock of the Company or any Affiliate. 

  
 21. 

 TDTX, INC. 

STOCK OPTION GRANT NOTICE 

(2019 EQUITY INCENTIVE PLAN) 
 TDTx,
Inc. (the “Company”), pursuant to its 2019 Equity Incentive Plan (as amended and/or restated as of the Date of Grant set forth below, the “Plan”), has granted to Optionholder an option to purchase
the number of shares of the Common Stock set forth below (the “Option”). The Option is subject to all of the terms and conditions as set forth in this Stock Option Grant Notice (the “Grant Notice”) and
in the Plan, the Option Agreement, and the Notice of Exercise, all of which are attached to this Grant Notice and incorporated into this Grant Notice in their entirety. Capitalized terms not explicitly defined in this Grant Notice but defined in the
Plan or the Option Agreement shall have the meanings set forth in the Plan or the Option Agreement, as applicable. If the Company uses an electronic capitalization table system (such as Carta or Shareworks) and the fields below are blank or the
information is otherwise provided in a different format electronically, the blank fields and other information (such as exercise schedule and type of grant) shall be deemed to come from the electronic capitalization system and is considered part of
this Grant Notice. 
  

			
	Optionholder:	  	  

	Date of Grant:	  	  

	Vesting Commencement Date:	  	  

	Number of Shares Subject to Option:	  	  

	Exercise Price (Per Share)1:	  	  

	Total Exercise Price:	  	  

	Expiration Date:	  	  

	Exercise Schedule:	  	[Same as Vesting Schedule] [Early Exercise Permitted]
		
	Type of Grant2:	  	[Incentive Stock Option] [Nonstatutory Stock Option]

  

			
	Vesting Schedule:	  	[Sample of standard vesting. 12/48ths of the total shares will vest on the one-year anniversary of the Vesting Commencement Date, and 1/48th of the total shares will vest each month
thereafter on the same day of the month as the Vesting Commencement Date (or if there is no corresponding day, on the last day of the month), subject to Optionholder’s Continuous Service as of each such date.]

  

	1 	 The exercise price may be paid by one or a combination of the methods permitted in the Option Agreement.

	2 	 If this is an Incentive Stock Option, it (plus other outstanding Incentive Stock Options) cannot be first
exercisable for more than $100,000 in value (measured by exercise price) in any calendar year. Any excess over $100,000 is a Nonstatutory Stock Option. 

 Optionholder Acknowledgements: By Optionholder’s signature below or by electronic acceptance or
authentication in a form authorized by the Company, Optionholder understands and agrees that the Option is governed by this Stock Option Grant Notice, and the provisions of the Plan and the Option Agreement and the Notice of Exercise, all of which
are made a part of this document. 
 By accepting this Option, Optionholder consents to receive this Grant Notice, the Option Agreement, the Plan, and any
other Plan-related documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the
Company. Optionholder represents that he or she has read and is familiar with the provisions of the Plan and the Option Agreement. Optionholder acknowledges and agrees that this Grant Notice and the Option Agreement may not be modified, amended or
revised except in writing signed by Optionholder and a duly authorized officer of the Company. 
 Optionholder further acknowledges that in the event of any
conflict between the provisions in this Grant Notice, the Option Agreement, the Notice of Exercise and the terms of the Plan, the terms of the Plan shall control. Optionholder further acknowledges that the Option Agreement sets forth the entire
understanding between Optionholder and the Company regarding the acquisition of Common Stock and supersedes all prior oral and written agreements, promises and/or representations on that subject with the exception of other equity awards previously
granted to Optionholder and any written employment agreement, offer letter, severance agreement, written severance plan or policy, or other written agreement between the Company and Optionholder in each case that specifies the terms that should
govern this Option. 
 Optionholder further acknowledges that this Grant Notice has been prepared on behalf of the Company by Cooley LLP, counsel to the
Company and that Cooley LLP does not represent, and is not acting on behalf of, Optionholder in any capacity. Optionholder has been provided with an opportunity to consult with Optionholder’s own counsel with respect to this Grant Notice. 

This Grant Notice may be executed in one or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and
the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other applicable law) or other
transmission method and any counterpart so delivered will be deemed to have been duly and validly delivered and be valid and effective for all purposes. 
  

									
	TDTx, Inc.	  		  	Optionholder:
					
	By:	  	  
	  		  	By:	  	  

		  	(Signature)	  		  		  	(Signature)
	Title:	  	  
	  		  	Email:	  	  

	Date:	  	  
	  		  	Date:	  	  

 Attachments: Option Agreement, 2019 Equity Incentive Plan and Notice of Exercise 

 TDTX, INC. 

2019 Equity Incentive Plan 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK OPTION) 

Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this Option Agreement, TDTx, Inc. (the
“Company”) has granted you an option under its 2019 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated in your Grant Notice at the exercise
price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between the terms in this Option Agreement and
the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. 

The details of your option, in addition to those set forth in the Grant Notice and the Plan, are as follows: 

1. Vesting. Your option will vest as provided in your Grant Notice. Vesting will cease upon the termination of your Continuous Service.

 2. Number of Shares and Exercise Price. The number of shares of Common Stock subject to your option and your exercise price per
share in your Grant Notice will be adjusted for Capitalization Adjustments. 
 3. Exercise Restriction for
Non-Exempt Employees. If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that is, a
“Non-Exempt Employee”), and except as otherwise provided in the Plan, you may not exercise your option until you have completed at least six months of Continuous Service measured from
the Date of Grant, even if you have already been an employee for more than six months. Consistent with the provisions of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such six month anniversary
in the case of (i) your death or disability, (ii) a Corporate Transaction in which your option is not assumed, continued or substituted, (iii) a Change in Control or (iv) your termination of Continuous Service on your
“retirement” (as defined in the Company’s benefit plans). 
 4. Exercise prior to Vesting (“Early Exercise”).
If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates “Early Exercise Permitted”) and subject to the provisions of your option, you may elect at any time that is both (i) during the period of your
Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the unvested portion of your option; provided, however, that: 

(a) a partial exercise of your option will be deemed to cover first vested shares of Common Stock and then the earliest vesting
installment of unvested shares of Common Stock; 
 (b) any shares of Common Stock so purchased from installments that have not vested
as of the date of exercise will be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement; 

  
 1. 

 (c) you will enter into the Company’s form of Early Exercise Stock Purchase
Agreement with a vesting schedule that will result in the same vesting as if no early exercise had occurred; and 
 (d) if your option
is an Incentive Stock Option, then, to the extent that the aggregate Fair Market Value (determined at the Date of Grant) of the shares of Common Stock with respect to which your option plus all other Incentive Stock Options you hold are exercisable
for the first time by you during any calendar year (under all plans of the Company and its Affiliates) exceeds $100,000, your option(s) or portions thereof that exceed such limit (according to the order in which they were granted) will be treated as
Nonstatutory Stock Options. 
 5. Method of Payment. You must pay the full amount of the exercise price for the shares you wish to
exercise. The permitted methods of payment are as follows: 
 (a) by cash, check, bank draft, electronic funds transfer or money order
payable to the Company; 
 (b) subject to Company and/or Board consent at the time of exercise and provided that at the time of
exercise the Common Stock is publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company
or the receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to
cover”; 
 (c) subject to Company and/or Board consent at the time of exercise and provided that at the time of exercise the
Common Stock is publicly traded, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock that are owned free and clear of any liens, claims, encumbrances or security interests, and that are
valued at Fair Market Value on the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company at the time you exercise your option, will include delivery to the Company of your attestation of ownership of such
shares of Common Stock in a form approved by the Company. You may not exercise your option by delivery to the Company of Common Stock if doing so would violate the provisions of any law, regulation or agreement restricting the redemption of the
Company’s stock; 
 (d) subject to Company and/or Board consent at the time of exercise, and provided that the Option is a
Nonstatutory Stock Option, by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of the Option by the largest whole number of shares with a Fair Market Value
that does not exceed the aggregate exercise price plus, to the extent permitted by the Company and/or Board at the time of exercise, the aggregate withholding obligations in respect of the Option exercise; provided, further that you must pay any
remaining balance of the aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock will no longer be subject to the Option and will not be exercisable thereafter to
the extent that (A) shares issuable upon exercise are used to pay the exercise price pursuant to the “net exercise,” (B) shares are delivered to you as a result of such exercise, and (C) shares are withheld to satisfy tax
withholding obligations; 
 (e) subject to the consent of the Company and/or Board at the time of exercise, according to a deferred
payment or similar arrangement with you; provided, however, that interest will compound at least annually and will be charged at the minimum rate of interest necessary to avoid (A) the imputation of interest income to the Company and
compensation income to the Optionholder under any applicable provisions of the Code, and (B) the classification of the Option as a liability for financial accounting purposes; or 

  
 2. 

 (f) in any other form of legal consideration that may be acceptable to the Board.

 6. Whole Shares. You may exercise your option only for whole shares of Common Stock. 

7. Securities Law Compliance. In no event may you exercise your option unless the shares of Common Stock issuable upon exercise are then
registered under the Securities Act or, if not registered, the Company has determined that your exercise and the issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must
comply with all other applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any
restrictions on exercise required for compliance with Treas. Reg. 1.401(k)-1(d)(3), if applicable). 

8. Term. You may not exercise your option before the Date of Grant or after the expiration of the option’s term. Except as set
forth in your Grant Notice, the term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

(a) immediately upon the termination of your Continuous Service for Cause; 

(b) three months after the termination of your Continuous Service for any reason other than Cause, your Disability or your death
(except as otherwise provided in Section 8(d) below); provided, however, that if during any part of such three month period your option is not exercisable solely because of the condition set forth in the section above relating to
“Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three months after the termination of your Continuous Service; provided
further, that if (i) you are a Non-Exempt Employee, (ii) your Continuous Service terminates within six months after the Date of Grant, and (iii) you have vested in a portion of your option
at the time of your termination of Continuous Service, your option will not expire until the earlier of (x) the later of (A) the date that is seven months after the Date of Grant, and (B) the date that is three months after the
termination of your Continuous Service, and (y) the Expiration Date; 
 (c) 12 months after the termination of your Continuous
Service due to your Disability (except as otherwise provided in Section 8(d)) below; 
 (d) 18 months after your death if you die
either during your Continuous Service or within three (3) months after your Continuous Service terminates for any reason other than Cause; 

(e) the Expiration Date indicated in your Grant Notice; or 

(f) the day before the 10th anniversary of the Date of Grant. 

If your option is an Incentive Stock Option, note that to obtain the federal income tax advantages associated with an Incentive Stock Option,
the Code requires that at all times beginning on the Date of Grant and ending on the day three months before the date of your option’s exercise, you must be an employee of the Company or an Affiliate, except in the event of your death or
Disability. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily be treated as an Incentive Stock Option if you continue to provide
services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three months after the date your employment with the Company or an Affiliate terminates. 

  
 3. 

 9. Exercise. 

(a) You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so permits) during
its term by delivering a Notice of Exercise (in a form designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the Company may designate, during regular business hours. If required by
the Company, your exercise may be made contingent on your execution of any additional documents specified by the Company (including, without limitation, any shareholders agreement, voting agreement, right of first refusal agreement or other
agreement between the Company and some or all of its stockholders). 
 (b) By exercising your option you agree that, as a condition to
any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option,
(ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c) If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company in writing within
15 days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two years after the Date of Grant or within one year after such shares of Common Stock are transferred upon
exercise of your option. 
 (d) By exercising your option you agree that you will not sell, dispose of, transfer, make any short sale
of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held by you, for a period of 180 days
following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar
rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this section will prevent the exercise of a repurchase option, if any, in favor of the
Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or
that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of Common Stock until the end of such period. You also agree that any
transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 9(d). The underwriters of the Company’s stock are intended third party beneficiaries of this Section 9(d) and will
have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 
 10.
Transferability. Except as otherwise provided in this Section 10, your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

(a) Certain Trusts. Upon receiving written permission from the Board or its duly authorized designee, you may transfer your
option to a trust if you are considered to be the sole beneficial owner (determined under Section 671 of the Code and applicable state law) while the option is held in the trust. You and the trustee must enter into transfer and other agreements
required by the Company. 

  
 4. 

 (b) Domestic Relations Orders. Upon receiving written permission from the
Board or its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to the terms of a domestic relations order, official
marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation 1.421-1(b)(2) that contains the information required by the Company to effectuate the transfer. You
are encouraged to discuss the proposed terms of any division of this option with the Company prior to finalizing the domestic relations order or marital settlement agreement to help ensure the required information is contained within the domestic
relations order or marital settlement agreement. If this option is an Incentive Stock Option, this option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(c) Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may, by
delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to exercise this option and
receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of your estate, the
Common Stock or other consideration resulting from such exercise. 
 11. Right of First Refusal. Shares of Common Stock that you
acquire upon exercise of your option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time the Company elects to exercise its right; provided, however, that if there is no right of
first refusal described in the Company’s bylaws at such time, the right of first refusal described below will apply. The Company’s right of first refusal will expire on the first date upon which any security of the Company is listed (or
approved for listing) upon notice of issuance on a national securities exchange or quotation system (the “Listing Date”). 

(a) Prior to the Listing Date, you may not validly Transfer (as defined below) any shares of Common Stock acquired upon exercise of your
option, or any interest in such shares, unless such Transfer is made in compliance with the following provisions: 
 (i) Before there
can be a valid Transfer of any shares of Common Stock or any interest therein, the record holder of the shares of Common Stock to be transferred (the “Offered Shares”) will give written notice (by registered or certified
mail) to the Company. Such notice will specify the identity of the proposed transferee, the cash price offered for the Offered Shares by the proposed transferee (or, if the proposed Transfer is one in which the holder will not receive cash, such as
an involuntary transfer, gift, donation or pledge, the holder will state that no purchase price is being proposed), and the other terms and conditions of the proposed Transfer. The date such notice is mailed will be hereinafter referred to as the
“Notice Date” and the record holder of the Offered Shares will be hereinafter referred to as the “Offeror.” If, from time to time, there is any stock dividend, stock split or other change in the
character or amount of any of the outstanding Common Stock which is subject to the provisions of your option, then in such event any and all new, substituted or additional securities to which you are entitled by reason of your ownership of the
shares of Common Stock acquired upon exercise of your option will be immediately subject to the Company’s Right of First Refusal (as defined below) with the same force and effect as the shares subject to the Right of First Refusal immediately
before such event. 
 (ii) For a period of 30 calendar days after the Notice Date, or such longer period as may be required to avoid
the classification of your option as a liability for financial accounting purposes, the Company will have the option to purchase all (but not less than all) of the Offered Shares at the purchase price and on the terms set forth in
Section 11(a)(iii) (the Company’s “Right of First  

  
 5. 

 
Refusal”). In the event that the proposed Transfer is one involving no payment of a purchase price, the purchase price will be deemed to be the Fair Market Value of the Offered
Shares as determined in good faith by the Board in its discretion. The Company may exercise its Right of First Refusal by mailing (by registered or certified mail) written notice of exercise of its Right of First Refusal to the Offeror prior to the
end of said 30 days (including any extension required to avoid classification of the option as a liability for financial accounting purposes). 

(iii) The price at which the Company may purchase the Offered Shares pursuant to the exercise of its Right of First Refusal will be the
cash price offered for the Offered Shares by the proposed transferee (as set forth in the notice required under Section 11(a)(i)), or the Fair Market Value as determined by the Board in the event no purchase price is involved. To the extent
consideration other than cash is offered by the proposed transferee, the Company will not be required to pay any additional amounts to the Offeror other than the cash price offered (or the Fair Market Value, if applicable). The Company’s notice
of exercise of its Right of First Refusal will be accompanied by full payment for the Offered Shares and, upon such payment by the Company, the Company will acquire full right, title and interest to all of the Offered Shares. 

(iv) If, and only if, the option given pursuant to Section 11(a)(ii) is not exercised, the Transfer proposed in the notice given
pursuant to Section 11(a)(i) may take place; provided, however, that such Transfer must, in all respects, be exactly as proposed in said notice except that such Transfer may not take place either before the 10th calendar day after the expiration of the 30 day option exercise period or after the ninetieth 90th calendar day after the expiration of the 30
day option exercise period, and if such Transfer has not taken place prior to said 90th day, such Transfer may not take place without once again complying with this Section 11(a). The option
exercise periods in this Section 11(a)(iv) will be adjusted to include any extension required to avoid the classification of your option as a liability for financial accounting purposes. 

(b) As used in this Section 11, the term “Transfer” means any sale, encumbrance, pledge, gift or other form
of disposition or transfer of shares of Common Stock or any legal or equitable interest therein; provided, however, that the term Transfer does not include a transfer of such shares or interests by will or intestacy to your Immediate Family
(as defined below). In such case, the transferee or other recipient will receive and hold the shares of Common Stock so transferred subject to the provisions of this Section, and there will be no further transfer of such shares except in accordance
with the terms of this Section 11. As used herein, the term “Immediate Family” will mean your spouse, the lineal descendant or antecedent, father, mother, brother or sister, child, adopted child, grandchild or adopted
grandchild of you or your spouse, or the spouse of any child, adopted child, grandchild or adopted grandchild of you or your spouse. 

(c) None of the shares of Common Stock purchased on exercise of your option will be transferred on the Company’s books nor will the
Company recognize any such Transfer of any such shares or any interest therein unless and until all applicable provisions of this Section 11 have been complied with in all respects. The certificates of stock evidencing shares of Common Stock
purchased on exercise of your option will bear an appropriate legend referring to the transfer restrictions imposed by this Section 11. 

(d) To ensure that the shares subject to the Company’s Right of First Refusal will be available for repurchase by the Company, the
Company may require you to deposit the certificates evidencing the shares that you purchase upon exercise of your option with an escrow agent designated by the Company under the terms and conditions of an escrow agreement approved by the Company. If
the Company does not require such deposit as a condition of exercise of your option, the Company reserves the right at any time to require you to so deposit the certificates in escrow. As soon as practicable after

  
 6. 

 
the expiration of the Company’s Right of First Refusal, the agent will deliver to you the shares and any other property no longer subject to such restriction. In the event the shares and any
other property held in escrow are subject to the Company’s exercise of its Right of First Refusal, the notices required to be given to you will be given to the escrow agent, and any payment required to be given to you will be given to the
escrow agent. Within 30 days after payment by the Company for the Offered Shares, the escrow agent will deliver the Offered Shares that the Company has repurchased to the Company and will deliver the payment received from the Company to you. 

12. Option not a Service Contract. Your option is not an employment or service contract, and nothing in your option will be deemed to
create in any way whatsoever any obligation on your part to continue in the employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an
Affiliate, their respective stockholders, boards of directors, officers or employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

13. Withholding Obligations. 

(a) At the time you exercise your option, in whole or in part, and at any time thereafter as requested by the Company, you hereby
authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “same day sale” pursuant to a program developed under Regulation T as promulgated by the
Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with the exercise of your
option. 
 (b) If this option is a Nonstatutory Stock Option, then upon your request and subject to approval by the Company, and
compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair
Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of your option as a liability for
financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence will not be permitted unless
you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the
determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock will be withheld solely from fully vested shares of Common Stock determined as of the date
of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure will be your sole responsibility. 

(c) You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied.
Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock from any
escrow provided for herein, if applicable, unless such obligations are satisfied. 

  
 7. 

 14. Tax Consequences. You hereby agree that the Company does not have a duty to
design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities
arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the Code only if the exercise price per share specified in the Grant Notice is at least equal to the “fair
market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated with the option. Because the Common Stock is not traded on an established securities market, the Fair
Market Value is determined by the Board, perhaps in consultation with an independent valuation firm retained by the Company. You acknowledge that there is no guarantee that the Internal Revenue Service will agree with the valuation as determined by
the Board, and you will not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates in the event that the Internal Revenue Service asserts that the valuation determined by the Board is less than the “fair
market value” as subsequently determined by the Internal Revenue Service. 
 15. Notices. Any notices provided for in your option
or the Plan will be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five days after deposit in the United States mail, postage prepaid,
addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means or to request your consent to
participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system
established and maintained by the Company or another third party designated by the Company. 
 16. Governing Plan Document. Your
option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and
adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. 

  
 8. 

 TDTX, INC. 

NOTICE OF EXERCISE 
 This constitutes
notice to TDTx, Inc. (the “Company”) under my stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below.
Use of certain payment methods is subject to Company and/or Board consent and certain additional requirements set forth in the Option Agreement and the Plan. If the Company uses an electronic capitalization table system (such as Carta or Shareworks)
and the fields below are blank, the blank fields shall be deemed to come from the electronic capitalization system and is considered part of this Notice of Exercise. 
  

			
	 Option Information
	  	
		
	 Type of option (check one):
	  	Incentive  ☐ Nonstatutory  ☐
		  	  

	 Stock option dated:
	  	
		  	  

	 Number of Shares as to which option is exercised:
	  	
		  	  

	 Certificates to be issued in name
of:3
	  	
		  	  

		
	Exercise Information	  	
		
	 Date of Exercise:
	  	
		  	  

	 Total exercise price:
	  	
		  	  

	 Cash:4
	  	
		  	  

	 Regulation T Program (cashless
exercise):5
	  	
		  	  

	 Value of _________ Shares delivered with this
notice:6
	  	
		  	  

	 Value of _________ Shares pursuant to net
exercise:7
	  	
		  	  

 By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the
terms of the 2019 Equity Incentive Plan to the Company (including, without limitation, any shareholders agreement, voting agreement, right of first refusal agreement or other agreement between the Company and some or all of its stockholders),
(ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) if this exercise relates to an incentive stock option, to notify you
in writing within 15 days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two years after the date of grant of this option or within one year after such Shares are issued upon exercise of
this option. I further agree that this Notice of Exercise may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other
applicable law) or other transmission method and will be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

I hereby make the following certifications and representations with respect to the number of Shares listed above, which are being acquired by
me for my own account upon exercise of the option as set forth above: 
  

	3 	 If left blank, will be issued in the name of the option holder. 

	4 	 Cash may be in the form of cash, check, bank draft, electronic funds transfer or money order payment.

	5 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. 

	6 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. Shares must be valued in accordance with the terms of the option being exercised, and must be owned free and clear of any liens, claims, encumbrances or security interests. Certificates must be endorsed or accompanied by an
executed assignment separate from certificate. 

	7 	 Subject to Company and/or Board consent and must be a Nonstatutory Option.

 I acknowledge that the Shares have not been registered under the Securities Act of 1933, as
amended (the “Securities Act”), and are deemed to constitute “restricted securities” under Rule 701 and Rule 144 promulgated under the Securities Act. I warrant and represent to the Company that I have no present
intention of distributing or selling said Shares, except as permitted under the Securities Act and any applicable state securities laws. 

I further acknowledge and agree that, except for such information as required to be delivered to me by the Company pursuant to the option or
the Plan (if any), I will have no right to receive any information from the Company by virtue of the grant of the option or the purchase of shares of Common Stock through exercise of the option, ownership of such shares of Common Stock, or as a
result of my being a holder of record of stock of the Company. Without limiting the foregoing, to the fullest extent permitted by law, I hereby waive all inspection rights under Section 220 of the Delaware General Corporation Law and all such
similar information and/or inspection rights that may be provided under the law of any jurisdiction, or any federal, state or foreign regulation, that are, or may become, applicable to the Company or the Company’s capital stock (the
“Inspection Rights”). I hereby covenant and agree never to directly or indirectly commence, voluntarily aid in any way, prosecute, assign, transfer, or cause to be commenced any claim, action, cause of action, or other
proceeding to pursue or exercise the Inspection Rights. 
 I further acknowledge that I will not be able to resell the Shares for at least
90 days after the stock of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934) under Rule 701 and that more restrictive conditions apply to
affiliates of the Company under Rule 144. 
 I further acknowledge that all certificates representing any of the Shares subject to the
provisions of the option will have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the Company’s Certificate of Incorporation, Bylaws and/or applicable
securities laws. 
 I further agree that, if required by the Company (or a representative of the underwriters) in connection with the first
underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar
transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company for a period of 180 days following the effective date of a registration statement of the Company filed under the
Securities Act (or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rule or regulation) (the “Lock-Up
Period”). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or that are necessary to give further effect thereto. In
order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to securities subject to the foregoing restrictions until the end of such period. 

Very truly yours, 
  

			
		  	  

		  	(Signature)
		
		  	  

		  	Name (Please Print)
		
	Address of Record:	  	  

		  	  

		  	  

		
	Email:	  	  

 TDTX, INC. 

NOTICE OF EXERCISE 
 This constitutes
notice to TDTx, Inc. (the “Company”) under my stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below.
Use of certain payment methods is subject to Company and/or Board consent and certain additional requirements set forth in the Option Agreement and the Plan. If the Company uses an electronic capitalization table system (such as Carta or Shareworks)
and the fields below are blank, the blank fields shall be deemed to come from the electronic capitalization system and is considered part of this Notice of Exercise. 
  

			
	Option Information	  	
		
	 Type of option (check one):
	  	Incentive  ☐         Nonstatutory  ☐
		  	  

	 Stock option dated:
	  	
		  	  

	 Number of Shares as to which option is exercised:
	  	
		  	  

	 Certificates to be issued in name
of:1
	  	
		  	  

		
	Exercise Information	  	
		
	 Date of Exercise:
	  	
		  	  

	 Total exercise price:
	  	
		  	  

	 Cash:2
	  	
		  	  

	 Regulation T Program (cashless
exercise):3
	  	
		  	  

	 Value of _________ Shares delivered with this
notice:4
	  	
		  	  

	 Value of _________ Shares pursuant to net
exercise:5
	  	
		  	  

 By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the
terms of the 2019 Equity Incentive Plan to the Company (including, without limitation, any shareholders agreement, voting agreement, right of first refusal agreement or other agreement between the Company and some or all of its stockholders),
(ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) if this exercise relates to an incentive stock option, to notify you
in writing within 15 days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two years after the date of grant of this option or within one year after such Shares are issued upon exercise of
this option. I further agree that this Notice of Exercise may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other
applicable law) or other transmission method and will be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

I hereby make the following certifications and representations with respect to the number of Shares listed above, which are being acquired by
me for my own account upon exercise of the option as set forth above: 
 I acknowledge that the Shares have not been registered under the
Securities Act of 1933, as amended (the “Securities Act”), and are deemed to constitute “restricted securities” under Rule 701 and Rule 144 promulgated under the Securities Act. I warrant and represent to the
Company that I have no present intention of distributing or selling said Shares, except as permitted under the Securities Act and any applicable state securities laws. 

 

	1 	 If left blank, will be issued in the name of the option holder. 

	2 	 Cash may be in the form of cash, check, bank draft, electronic funds transfer or money order payment.

	3 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. 

	4 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. Shares must be valued in accordance with the terms of the option being exercised, and must be owned free and clear of any liens, claims, encumbrances or security interests. Certificates must be endorsed or accompanied by an
executed assignment separate from certificate. 

	5 	 Subject to Company and/or Board consent and must be a Nonstatutory Option.

 I further acknowledge and agree that, except for such information as required to be
delivered to me by the Company pursuant to the option or the Plan (if any), I will have no right to receive any information from the Company by virtue of the grant of the option or the purchase of shares of Common Stock through exercise of the
option, ownership of such shares of Common Stock, or as a result of my being a holder of record of stock of the Company. Without limiting the foregoing, to the fullest extent permitted by law, I hereby waive all inspection rights under
Section 220 of the Delaware General Corporation Law and all such similar information and/or inspection rights that may be provided under the law of any jurisdiction, or any federal, state or foreign regulation, that are, or may become,
applicable to the Company or the Company’s capital stock (the “Inspection Rights”). I hereby covenant and agree never to directly or indirectly commence, voluntarily aid in any way, prosecute, assign, transfer, or cause
to be commenced any claim, action, cause of action, or other proceeding to pursue or exercise the Inspection Rights. 
 I further
acknowledge that I will not be able to resell the Shares for at least 90 days after the stock of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of
1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company under Rule 144. 
 I further acknowledge that
all certificates representing any of the Shares subject to the provisions of the option will have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the
Company’s Certificate of Incorporation, Bylaws and/or applicable securities laws. 
 I further agree that, if required by the Company
(or a representative of the underwriters) in connection with the first underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any
option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company for a period of 180 days following the effective date
of a registration statement of the Company filed under the Securities Act (or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rule or regulation) (the
“Lock-Up Period”). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing
or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to securities subject to the foregoing
restrictions until the end of such period. 
 Very truly yours, 

 

			
		  	  

		  	(Signature)
		
		  	  

		  	Name (Please Print)
		
	Address of Record:	  	  

		  	  

		  	  

		
	Email:	  	  

 TDTX, INC. 

EARLY EXERCISE STOCK PURCHASE AGREEMENT 

UNDER THE 2019 EQUITY INCENTIVE PLAN 

This Agreement is made by and between TDTx, Inc., a Delaware corporation (the “Company”), and the
individual designated on the signature page hereto as a Purchaser (“Purchaser”). 
 Recitals: 

A. Purchaser holds a stock option, granted on [•], to purchase [•] shares of common
stock (“Common Stock”) of the Company (the “Option”) pursuant to the Company’s 2019 Equity Incentive Plan (as amended and/or restated, the “Plan”). 

B. The Option consists of a Stock Option Grant Notice and a Stock Option Agreement. 

C. Purchaser desires to exercise the Option on the terms and conditions contained herein. 

D. Purchaser wishes to take advantage of the early exercise provision of Purchaser’s Option and therefore to enter into this
Agreement. 
 The parties agree as follows: 

1. Incorporation of Plan and Option by Reference. This Agreement is subject to all of the terms and conditions as set forth in
the Plan and the Option. If there is a conflict between the terms of this Agreement and/or the Option and the terms of the Plan, the terms of the Plan will control. If there is a conflict between the terms of this Agreement and the terms of the
Option, the terms of the Option will control. Defined terms not explicitly defined in this Agreement but defined in the Plan will have the same definitions as in the Plan. Defined terms not explicitly defined in this Agreement or the Plan but
defined in the Option will have the same definitions as in the Option. 
 2. Purchase and Sale of Common Stock. 

(a) Agreement to purchase and sell Common Stock. Purchaser hereby agrees to purchase from the Company, and the Company hereby
agrees to sell to Purchaser, shares of the Common Stock of the Company in accordance with the Notice of Exercise duly executed by Purchaser and attached hereto as Exhibit A. 

(b) Closing. The closing hereunder, including payment for and delivery of the Common Stock, will occur at the offices of the Company
immediately following the execution of this Agreement, or at such other time and place as the parties may mutually agree; provided, however, that if stockholder approval of the Plan is required before the Option may be exercised, then the
Option may not be exercised, and the closing will be delayed, until such stockholder approval is obtained. If such stockholder approval is not obtained within the time limit specified in the Plan, then this Agreement is null and void. 

3. Unvested Share Repurchase Option. 

(a) Repurchase Option. In the event Purchaser’s Continuous Service terminates, then the Company has an irrevocable option (the
“Repurchase Option”) for a period of six months after said termination (or in the case of shares issued upon exercise of the Option after such date of termination, within six months after the date of the exercise), or such
longer period as may be agreed to by the 

 Company and Purchaser (the “Repurchase Period”), to repurchase from Purchaser or
Purchaser’s personal representative, as the case may be, those shares that Purchaser received pursuant to the exercise of the Option that have not as yet vested as of such termination date in accordance with the Vesting Schedule indicated on
Purchaser’s Stock Option Grant Notice (the “Unvested Shares”). 
 (b) Share Repurchase
Price. The Company may repurchase all or any of the Unvested Shares at the lower of (i) the Fair Market Value of the such shares (as determined under the Plan) on the date of repurchase, or (ii) the price equal to
Purchaser’s Exercise Price for such shares as indicated on Purchaser’s Stock Option Grant Notice. 
 4. Exercise of
Repurchase Option. The Repurchase Option will be exercised by written notice signed by such person as designated by the Company, and delivered or mailed as provided herein. Such notice will identify the number of shares of Common Stock to be
purchased and will notify Purchaser of the time, place and date for settlement of such purchase, which will be scheduled by the Company within the term of the Repurchase Option set forth above. In addition, the Company will be deemed to have
exercised the Repurchase Option as of the last day of the Repurchase Period, unless an officer of the Company notifies the holder of the Unvested Shares during the Repurchase Period in writing (delivered or mailed as provided herein) that the
Company expressly declines to exercise its Repurchase Option for some or all of the Unvested Shares. The Company will be entitled to pay for any shares of Common Stock purchased pursuant to its Repurchase Option at the Company’s option in cash
or by offset against any indebtedness owing to the Company by Purchaser (including without limitation any Promissory Note given in payment for the Common Stock), or by a combination of both. Upon exercise of the Repurchase Option and payment of the
purchase price in any of the ways described above, the Company will become the legal and beneficial owner of the Common Stock being repurchased and all rights and interest therein or related thereto, and the Company will have the right to transfer
to its own name the Common Stock being repurchased by the Company, without further action by Purchaser. 
 5. Capitalization Adjustments
to Common Stock. In the event of a Capitalization Adjustment, then any and all new, substituted or additional securities or other property to which Purchaser is entitled by reason of Purchaser’s ownership of Common Stock will
be immediately subject to the Repurchase Option and be included in the word “Common Stock” for all purposes of the Repurchase Option with the same force and effect as the shares of the Common Stock presently subject to the Repurchase
Option, but only to the extent the Common Stock is, at the time, covered by such Repurchase Option. While the total Option Price will remain the same after each such event, the Option Price per share of Common Stock upon exercise of the Repurchase
Option will be appropriately adjusted. 
 6. Corporate Transactions. In the event of a Corporate Transaction, then the
Repurchase Option may be assigned by the Company to the successor of the Company (or such successor’s parent company), if any, in connection with such Corporate Transaction. To the extent the Repurchase Option remains in effect following such
Corporate Transaction, it will apply to the new capital stock or other property received in exchange for the Common Stock in consummation of the Corporate Transaction, but only to the extent the Common Stock was at the time covered by such right.
Appropriate adjustments will be made to the price per share payable upon exercise of the Repurchase Option to reflect the Corporate Transaction upon the Company’s capital structure; provided, however, that the aggregate price payable
upon exercise of the Repurchase Option remains the same. 
 7. Escrow of Unvested Common Stock. As security for Purchaser’s
faithful performance of the terms of this Agreement and to insure the availability for delivery of Purchaser’s Common Stock upon exercise of the Repurchase Option herein provided for, Purchaser agrees, at the closing hereunder, to deliver to
and deposit with the Secretary of the Company or the Secretary’s designee (“Escrow Agent”), as Escrow Agent in this transaction, three stock assignments duly endorsed (with date and number of

  
 2. 

 
shares blank) in the form attached hereto as Exhibit B, together with a certificate or certificates evidencing all of the Common Stock subject to the Repurchase Option; said documents are to be
held by the Escrow Agent and delivered by said Escrow Agent pursuant to the Joint Escrow Instructions of the Company and Purchaser set forth in Exhibit C, attached hereto and incorporated by this reference, which instructions also will be delivered
to the Escrow Agent at the closing hereunder. 
 8. Rights of Purchaser. Subject to the provisions of the Option, Purchaser will
exercise all rights and privileges of a stockholder of the Company with respect to the shares deposited in escrow. Purchaser will be deemed to be the holder of the shares for purposes of receiving any dividends that may be paid with respect to such
shares and for purposes of exercising any voting rights relating to such shares, even if some or all of such shares have not yet vested and been released from the Company’s Repurchase Option. 

9. Limitations on Transfer. In addition to any other limitation on transfer created by applicable securities laws, Purchaser will not
sell, assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Common Stock while the Common Stock is subject to the Repurchase Option. After any Common Stock has been released from the Repurchase Option, Purchaser will not
sell, assign, hypothecate, donate, encumber or otherwise dispose of any interest in the Common Stock except in compliance with the provisions herein and applicable securities laws. Furthermore, the Common Stock is subject to any right of first
refusal in favor of the Company or its assignees or other transfer restrictions that may be contained in the Company’s Bylaws. 
 10.
Restrictive Legends. All certificates representing the Common Stock will have endorsed thereon legends in substantially the following forms (in addition to any other legend which may be required by other agreements between the parties hereto):

 (a) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO AN OPTION SET FORTH IN AN AGREEMENT BETWEEN THE COMPANY AND THE
REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL OFFICE OF THIS COMPANY. ANY TRANSFER OR ATTEMPTED TRANSFER OF ANY SHARES SUBJECT TO SUCH OPTION IS VOID WITHOUT THE PRIOR EXPRESS WRITTEN
CONSENT OF THE COMPANY.” 
 (b) “THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933 AS AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH
REGISTRATION IS NOT REQUIRED.” 
 (c) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL
OPTION IN FAVOR OF THE COMPANY AND/OR ITS ASSIGNEE(S) AS PROVIDED IN THE BYLAWS OF THE COMPANY AND IN AN AGREEMENT WITH THE COMPANY.” 

(d) “THE SHARES REPRESENTED BY THIS CERTIFICATE WERE ISSUED PURSUANT TO THE EXERCISE OF [AN INCENTIVE STOCK OPTION/ A
NONSTATUTORY STOCK OPTION].” 
 (e) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A TRANSFER RESTRICTION,
AS PROVIDED IN THE BYLAWS OF THE COMPANY.” 

  
 3. 

 (f) Any legend required by appropriate blue sky officials. 

11. Investment Representations. In connection with the purchase of the Common Stock, Purchaser represents to the Company the
following: 
 (a) Purchaser is aware of the Company’s business affairs and financial condition and has acquired sufficient
information about the Company to reach an informed and knowledgeable decision to acquire the Common Stock. Purchaser is acquiring the Common Stock for investment for Purchaser’s own account only and not with a view to, or for resale in
connection with, any “distribution” thereof within the meaning of the Securities Act. 
 (b) Purchaser understands that the
Common Stock has not been registered under the Securities Act by reason of a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Purchaser’s investment intent as expressed herein. 

(c) Purchaser further acknowledges and understands that the Common Stock must be held indefinitely unless the Common Stock is
subsequently registered under the Securities Act or an exemption from such registration is available. Purchaser further acknowledges and understands that the Company is under no obligation to register the Common Stock. Purchaser understands that the
certificate evidencing the Common Stock will be imprinted with a legend that prohibits the transfer of the Common Stock unless the Common Stock is registered or such registration is not required in the opinion of counsel for the Company. 

(d) Purchaser is familiar with the provisions of Rules 144 and 701, under the Securities Act, as in effect from time to time,
which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public offering
subject to the satisfaction of certain conditions. Rule 701 provides that if the issuer qualifies under Rule 701 at the time of issuance of the securities, such issuance will be exempt from registration under the Securities Act. In the event the
Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the securities exempt under Rule 701 may be sold by Purchaser 90 days thereafter, subject to the satisfaction of certain
of the conditions specified by Rule 144 and the market stand-off provision described in Purchaser’s Stock Option Agreement. 

(e) In the event that the sale of the Common Stock does not qualify under Rule 701 at the time of purchase, then the Common Stock
may be resold by Purchaser in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company, and (ii) the resale occurring
following the required holding period under Rule 144 after Purchaser has purchased, and made full payment of (within the meaning of Rule 144), the securities to be sold. 

(f) Purchaser further understands that at the time Purchaser wishes to sell the Common Stock there may be no public market upon which to
make such a sale, and that, even if such a public market then exists, the Company may not be satisfying the current public current information requirements of Rule 144 or 701, and that, in such event, Purchaser would be precluded from selling the
Common Stock under Rule 144 or 701 even if the minimum holding period requirement had been satisfied. 

  
 4. 

 (g) Purchaser further warrants and represents that Purchaser has either
(i) preexisting personal or business relationships, with the Company or any of its officers, directors or controlling persons, or (ii) the capacity to protect his own interests in connection with the purchase of the Common Stock by virtue
of the business or financial expertise of Purchaser or of professional advisors to Purchaser who are unaffiliated with and who are not compensated by the Company or any of its affiliates, directly or indirectly. Purchaser further warrants and
represents that Purchaser’s purchase the Common Stock was not accomplished by the publication of any advertisement. 
 12.
Section 83(b) Election. Purchaser understands that Section 83(a) of the Code taxes as ordinary income the difference between the amount paid for the Common Stock and the fair market value of the Common Stock as of
the date any restrictions on the Common Stock lapse. In this context, “restriction” includes the right of the Company to buy back the Common Stock pursuant to the Repurchase Option set forth above. Purchaser understands that Purchaser may
elect to be taxed at the time the Common Stock is purchased, rather than when and as the Repurchase Option expires, by filing an election under Section 83(b) (an “83(b) Election”) of the Code with the Internal Revenue
Service within 30 days of the date of purchase, a copy of which is included as Exhibit D. Even if the fair market value of the Common Stock at the time of the execution of this Agreement equals the amount paid for the Common Stock, the 83(b)
Election must be made to avoid income under Section 83(a) in the future. Purchaser understands that failure to file such an 83(b) Election in a timely manner may result in adverse tax consequences for Purchaser. Purchaser further understands
that Purchaser must file an additional copy of such 83(b) Election with his or her federal income tax return for the calendar year in which the date of this Agreement falls. Purchaser acknowledges that the foregoing is only a summary of the effect
of United States federal income taxation with respect to purchase of the Common Stock hereunder, and does not purport to be complete. Purchaser further acknowledges that the Company has directed Purchaser to seek independent advice regarding the
applicable provisions of the Code, the income tax laws of any municipality, state or foreign country in which Purchaser may reside, and the tax consequences of Purchaser’s death. Purchaser assumes all responsibility for filing an 83(b) Election
and paying all taxes resulting from such election or the lapse of the restrictions on the Common Stock. 
 13. Refusal to Transfer.
The Company is not required (a) to transfer on its books any shares of Common Stock of the Company which have been transferred in violation of any of the provisions set forth in this Agreement, or (b) to treat as owner of such shares
or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares have been so transferred. 
 14. No
Employment Rights. This Agreement is not an employment contract and nothing in this Agreement affects in any manner whatsoever the right or power of the Company or its Affiliates to terminate Purchaser’s employment for any reason at any
time, with or without cause and with or without notice. 
 15. Miscellaneous. 

(a) Notices. All notices required or permitted hereunder will be in writing and will be deemed effectively given: (i) upon personal
delivery to the party to be notified, (ii) when sent by confirmed facsimile if sent during normal business hours of the recipient, and if not during normal business hours of the recipient, then on the next business day, (iii) five calendar
days after having been sent by registered or certified mail, return receipt requested, postage prepaid, or (iv) one business day after deposit with a nationally recognized overnight courier, specifying next day delivery, with written
verification of receipt. All communications will be sent to the other party hereto at such party’s address hereinafter set forth on the signature page hereof, or at such other address as such party may designate by 10 days advance written
notice to the other party hereto. 

  
 5. 

 (b) Successors and Assigns. This Agreement will inure to the benefit of the
successors and assigns of the Company and, subject to the restrictions on transfer herein set forth, be binding upon Purchaser, Purchaser’s successors, and assigns. The Company may assign the Repurchase Option hereunder at any time or from time
to time, in whole or in part. 
 (c) Attorneys’ Fees; Specific Performance. Purchaser will reimburse the Company for all costs
incurred by the Company in enforcing the performance of, or protecting its rights under, any part of this Agreement, including reasonable costs of investigation and attorneys’ fees. It is the intention of the parties that the Company, upon
exercise of the Repurchase Option and payment for the shares repurchased, pursuant to the terms of this Agreement, will be entitled to receive the Common Stock, in specie, in order to have such Common Stock available for future issuance
without dilution of the holdings of other stockholders. Furthermore, it is expressly agreed between the parties that money damages are inadequate to compensate the Company for the Common Stock and that the Company will, upon proper exercise of the
Repurchase Option, be entitled to specific enforcement of its rights to purchase and receive said Common Stock. 
 (d) Governing Law;
Venue. This Agreement will be governed by and construed in accordance with the laws of the State of Delaware. The parties agree that any action brought by either party to interpret or enforce any provision of this Agreement will be brought in,
and each party agrees to, and does hereby, submit to the jurisdiction and venue of, the appropriate state or federal court for the district encompassing the Company’s principal place of business. 

(e) Further Execution. The parties agree to take all such further action(s) as may reasonably be necessary to carry out and consummate
this Agreement as soon as practicable, and to take whatever steps may be necessary to obtain any governmental approval in connection with or otherwise qualify the issuance of the securities that are the subject of this Agreement. 

(f) Independent Counsel. Purchaser acknowledges that this Agreement has been prepared on behalf of the Company by Cooley LLP, counsel to
the Company and that Cooley LLP does not represent, and is not acting on behalf of, Purchaser in any capacity. Purchaser has been provided with an opportunity to consult with Purchaser’s own counsel with respect to this Agreement. 

(g) Entire Agreement; Amendment. This Agreement constitutes the entire agreement between the parties with respect to the subject matter
hereof and supersedes and merges all prior agreements or understandings, whether written or oral. This Agreement may not be amended, modified or revoked, in whole or in part, except by an agreement in writing signed by each of the parties hereto.

 (h) Severability. If one or more provisions of this Agreement are held to be unenforceable under applicable law, the parties agree
to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision will be excluded from this Agreement, (ii) the balance of
the Agreement will be interpreted as if such provision were so excluded and (iii) the balance of the Agreement will be enforceable in accordance with its terms. 

(i) Counterparts. This Agreement may be executed in two or more counterparts, each of which will be deemed an original, but all of which
together will constitute one and the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or
other applicable law) or other transmission method and any counterpart so delivered will be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

  
 6. 

 [Remainder of page intentionally left blank] 

The parties hereto have executed this Agreement as of _______________. 

 

			
	COMPANY:
	
	TDTX, INC.
		
	By:	 	  

		 	Name:                                     
                                        
            
		 	Title:                                     
                                         
           
		
	Email:	 	  

	
	PURCHASER:
	  

	(Signature)
	  

	Name (Please Print)
	  

	Email

 ATTACHMENTS: 
  

			
	Exhibit A	  	Notice of Exercise
	Exhibit B	  	Assignment Separate from Certificate
	Exhibit C	  	Joint Escrow Instructions
	Exhibit D	  	Form of 83(b) Election

 [Signature Page to Early Exercise Stock Purchase Agreement] 

 EXHIBIT A 

NOTICE OF EXERCISE 

 TDTX, INC. 

NOTICE OF EXERCISE 
 This constitutes
notice to TDTx, Inc. (the “Company”) under my stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below.
Use of certain payment methods is subject to Company and/or Board consent and certain additional requirements set forth in the Option Agreement and the Plan. If the Company uses an electronic capitalization table system (such as Carta or Shareworks)
and the fields below are blank, the blank fields shall be deemed to come from the electronic capitalization system and is considered part of this Notice of Exercise. 
  

			
	 Option Information
	  	
		
	 Type of option (check one):
	  	Incentive  ☐         Nonstatutory  ☐
		  	  

	 Stock option dated:
	  	
		  	  

	 Number of Shares as to which option is exercised:
	  	
		  	  

	 Certificates to be issued in name
of:1
	  	
		  	  

		
	Exercise Information	  	
		
	 Date of Exercise:
	  	
		  	  

	 Total exercise price:
	  	
		  	  

	 Cash:2
	  	
		  	  

	 Regulation T Program (cashless
exercise):3
	  	
		  	  

	 Value of _________ Shares delivered with this
notice:4
	  	
		  	  

	 Value of _________ Shares pursuant to net
exercise:5
	  	
		  	  

 By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the
terms of the 2019 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) if this exercise relates to
an incentive stock option, to notify you in writing within 15 days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two years after the date of grant of this option or within one year
after such Shares are issued upon exercise of this option. I further agree that this Notice of Exercise may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000,
Uniform Electronic Transactions Act or other applicable law) or other transmission method and will be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

I hereby make the following certifications and representations with respect to the number of Shares listed above, which are being acquired by
me for my own account upon exercise of the option as set forth above: 
 I acknowledge that the Shares have not been registered under the
Securities Act of 1933, as amended (the “Securities Act”), and are deemed to constitute “restricted securities” under Rule 701 and Rule 144 promulgated under the Securities Act. I warrant and represent to the
Company that I have no present intention of distributing or selling said Shares, except as permitted under the Securities Act and any applicable state securities laws. 

 

	1 	 If left blank, will be issued in the name of the option holder. 

	2 	 Cash may be in the form of cash, check, bank draft, electronic funds transfer or money order payment.

	3 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. 

	4 	 Subject to Company and/or Board consent and must meet the public trading and other requirements set forth in
the Option Agreement. Shares must be valued in accordance with the terms of the option being exercised, and must be owned free and clear of any liens, claims, encumbrances or security interests. Certificates must be endorsed or accompanied by an
executed assignment separate from certificate. 

	5 	 Subject to Company and/or Board consent and must be a Nonstatutory Option.

 I further acknowledge and agree that, except for such information as required to be
delivered to me by the Company pursuant to the option or the Plan (if any), I will have no right to receive any information from the Company by virtue of the grant of the option or the purchase of shares of Common Stock through exercise of the
option, ownership of such shares of Common Stock, or as a result of my being a holder of record of stock of the Company. Without limiting the foregoing, to the fullest extent permitted by law, I hereby waive all inspection rights under
Section 220 of the Delaware General Corporation Law and all such similar information and/or inspection rights that may be provided under the law of any jurisdiction, or any federal, state or foreign regulation, that are, or may become,
applicable to the Company or the Company’s capital stock (the “Inspection Rights”). I hereby covenant and agree never to directly or indirectly commence, voluntarily aid in any way, prosecute, assign, transfer, or cause
to be commenced any claim, action, cause of action, or other proceeding to pursue or exercise the Inspection Rights. 
 I further
acknowledge that I will not be able to resell the Shares for at least 90 days after the stock of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of
1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company under Rule 144. 
 I further acknowledge that
all certificates representing any of the Shares subject to the provisions of the option will have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the
Company’s Certificate of Incorporation, Bylaws and/or applicable securities laws. 
 I further agree that, if required by the Company
(or a representative of the underwriters) in connection with the first underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any
option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company for a period of 180 days following the effective date
of a registration statement of the Company filed under the Securities Act (or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rule or regulation) (the
“Lock-Up Period”). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing
or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to securities subject to the foregoing
restrictions until the end of such period. 
 Very truly yours, 

 

			
		  	  

		  	(Signature)
		
		  	  

		  	Name (Please Print)
		
	Address of Record:	  	  

		  	  

		  	  

		
	Email:	  	  

  
 2. 

 EXHIBIT B 

STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE 

For Value Received, the undersigned hereby sells, assigns and transfers unto TDTx, Inc., a Delaware corporation (the
“Company”), pursuant to the Repurchase Option under that certain Early Exercise Stock Purchase Agreement, dated [______________], by and between the undersigned and the Company (the “Agreement”)
__________________ shares of Common Stock of the Company standing in the undersigned’s name on the books of the Company represented by Certificate No[s] ________________ and does hereby irrevocably constitute and appoint both the Company’s
Secretary and the Company’s attorney, or either of them, to transfer said stock on the books of the Company with full power of substitution in the premises. This Assignment may be used only in accordance with and subject to the terms and
conditions of the Agreement, in connection with the repurchase of shares of Common Stock issued to the undersigned pursuant to the Agreement, and only to the extent that such shares remain subject to the Company’s Repurchase Option under the
Agreement. 
  

					
	 Dated: __________________________
	 		  	
	(leave
blank)                                        
        	 		  	  

		 		  	(Signature)
		 		  	  

		 		  	Name (Please Print)

 Instruction: Please do not fill in any blanks other than the signature line. Do not fill in the date
line. The purpose of this Assignment is to enable the Company to exercise its Repurchase Option set forth in the Agreement without requiring additional signatures on the part of Purchaser. 

 EXHIBIT C 

JOINT ESCROW INSTRUCTIONS 

 JOINT ESCROW INSTRUCTIONS 

________, 20__ 
 Secretary 

TDTx, Inc. 
 One Broadway, 14th Floor 

Kendall Square 
 Cambridge, Massachusetts 02142 

Ladies and Gentlemen: 
 As Escrow Agent for both TDTx,
Inc., a Delaware corporation (“Company”) and the purchaser listed on the signature page hereto (“Purchaser”), you are hereby authorized and directed to hold the documents delivered to you pursuant
to the terms of that certain Early Exercise Stock Purchase Agreement dated as of _______________ (“Agreement”), to which a copy of these Joint Escrow Instructions is attached as an Exhibit, in accordance with the following
instructions: 
 1. In the event Company or an assignee elects to exercise the Repurchase Option set forth in the Agreement, the
Company or its assignee will give to Purchaser and you a written notice specifying the number of shares of stock to be acquired and the time for a closing thereunder at the principal office of the Company. Purchaser and the Company hereby
irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice. 

2. At the closing, you are directed (a) to date the stock assignments necessary for the transfer in question, (b) to fill in
the number of shares being transferred, and (c) to deliver the same, together with the certificate evidencing the shares of stock to be transferred, to the Company. 

3. Purchaser irrevocably authorizes the Company to deposit with you any certificates evidencing shares of stock to be held by you
hereunder and any additions and substitutions to said shares as specified in the Agreement. Purchaser does hereby irrevocably constitute and appoint you as his
attorney-in-fact and agent for the term of this escrow to execute with respect to such securities all documents necessary or appropriate to make such securities
negotiable and complete any transaction herein contemplated, including but not limited to any appropriate filing with state or government officials or bank officials. Subject to the provisions of this paragraph 3, Purchaser will exercise all rights
and privileges of a stockholder of the Company while the stock is held by you. 
 4. This escrow terminates and the shares of stock
held hereunder are released in full upon the exercise or expiration in full of the Repurchase Option, whichever occurs first. 
 5. If
at the time of termination of this escrow under Section 4 herein you should have in your possession any documents, securities, or other property belonging to Purchaser, you will deliver all of the same to Purchaser and will be discharged of all
further obligations hereunder; provided, however, that if at the time of termination of this escrow you are advised by the Company that any property subject to this escrow is the subject of a pledge or other security agreement, you will deliver all
such property to the pledgeholder or other person designated by the Company. 
 6. Except as otherwise provided in these Joint Escrow
Instructions, your duties hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties hereto. 

 7. You are obligated only for the performance of such duties as are specifically set
forth herein and may rely and are protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by the proper party or parties. You are not personally liable for any
act you may do or omit to do hereunder as Escrow Agent or as attorney-in-fact for Purchaser while acting in good faith and in the exercise of your own good judgment, and
any act done or omitted by you pursuant to the advice of your own attorneys is conclusive evidence of such good faith. 
 8. You are
hereby expressly authorized to disregard any and all warnings given by any of the parties hereto or by any other person or entity, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders,
judgments or decrees of any court. In case you obey or comply with any such order, judgment or decree of any court, you are not liable to any of the parties hereto or to any other person, firm or corporation by reason of such compliance,
notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have been entered without jurisdiction. 

9. You are not liable in any respect on account of the identity, authorities or rights of the parties executing or delivering or
purporting to execute or deliver these Joint Escrow Instructions documents or papers deposited or called for hereunder. 
 10. You are
not liable for the outlawing of any rights under any statute of limitations with respect to these Joint Escrow Instructions or any documents deposited with you. 

11. Your responsibilities as Escrow Agent hereunder terminate if you cease to be Secretary of the Company or if you resign by written
notice to the Company. In the event of any such termination, the Secretary of the Company will automatically become the successor Escrow Agent unless the Company appoints another successor Escrow Agent, and Purchaser hereby confirms the appointment
of such successor as Purchaser’s attorney-in-fact and agent to the full extent of your appointment. 

12. If you reasonably require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect
hereto, the necessary parties hereto will join in furnishing such instruments. 
 13. It is understood and agreed that should any
dispute arise with respect to the delivery and/or ownership or right of possession of the securities held by you hereunder, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities
until such dispute has been settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but
you will be under no duty whatsoever to institute or defend any such proceedings. 
 14. All notices required or permitted hereunder
will be in writing and will be deemed effectively given: (a) upon personal delivery to the party to be notified, (b) when sent by confirmed telex or facsimile if sent during normal business hours of the recipient, and if not during normal
business hours of the recipient, then on the next business day, (c) five (5) calendar days after having been sent by registered or certified mail, return receipt requested, postage prepaid, or (d) one (1) business day after deposit with a
nationally recognized overnight courier, specifying next day delivery, with written verification of receipt. All communications will be sent to the other party hereto at such party’s address set forth below, or at such other address as such
party may designate by ten (10) days advance written notice to the other party hereto. 

  
 2. 

 
			
	Company:	  	TDTx, Inc.
		
		  	 One Broadway, 14th Floor
 Kendall
Square

		  	 Cambridge, Massachusetts 02142
 Attn: Chief
Executive Officer

		
	Purchaser:	  	                                      
                      
		  	                                      
                      
		  	                                      
                      
		
	Escrow Agent:	  	TDTx, Inc.
		  	 One Broadway, 14th Floor
 Kendall
Square

		  	 Cambridge, Massachusetts 02142
 Attn:
Secretary

 15. By signing these Joint Escrow Instructions, you become a party hereto only for the purpose of
said Joint Escrow Instructions; you do not become a party to the Agreement. 
 16. You are entitled to employ such legal counsel and
other experts (including, without limitation, the firm of Cooley LLP) as you may deem necessary properly to advise you in connection with your obligations hereunder. You may rely upon the advice of such counsel, and you may pay such counsel
reasonable compensation therefor. The Company is responsible for all fees generated by such legal counsel in connection with your obligations hereunder. 

17. This instrument is binding upon and inures to the benefit of the parties hereto and their respective successors and permitted
assigns. It is understood and agreed that references to “you” and “your” herein refer to the original Escrow Agents and to any and all successor Escrow Agents. It is understood and agreed that the Company may at any time or from
time to time assign its rights under the Agreement and these Joint Escrow Instructions in whole or in part. 
 [Remainder of page
intentionally left blank] 

  
 3. 

 18. These Joint Escrow Instructions are governed by and interpreted and determined in
accordance with the laws of the State of Delaware, as such laws are applied by Delaware courts to contracts made and to be performed entirely in Delaware by residents of that state. The parties hereby expressly consent to the personal jurisdiction
of the state and federal courts located in the county in which the Company has its principal offices for any lawsuit arising from or related to this Agreement. 

Very truly yours, 
  

			
	COMPANY:
	
	TDTx, Inc.
		
	By:	 	  

		 	Name:                                     
                                    
		 	Title:
                                         
                               
	
	PURCHASER:
	
	  

	(Signature)
	
	  

	Name (Please Print)

  

	
	Escrow Agent:
	  

	Artur Adib, Secretary

 [Signature Page to Joint Escrow Instructions] 

 EXHIBIT D 

83(b) ELECTION 

 [This Form is designed for Individual purchasers. Corporate or Trust purchasers should
contact their Tax Professional to review before submitting.] 
 Instructions for Filing Section 83(b) Election 

Attached is a form of election under Section 83(b) of the Internal Revenue Code and an accompanying IRS cover letter. Please fill in your
[social security number][taxpayer identification number] and sign the election and cover letter, then proceed as follows: 
 (a) Make
three copies of the completed election form and one copy of the IRS cover letter. 
 (b) Send the original signed election
form and cover letter, the copy of the cover letter, and a self-addressed stamped return envelope to the Internal Revenue Service Center where you would otherwise file your tax return6. Even if an
address for an Internal Revenue Service Center is already included in the forms below, it is your obligation to verify such address. This can be done by searching for the term “where to file” on www.irs.gov or by calling 1 (800) 829-1040. 
 Sending the election via certified mail, requesting a return receipt, with the certified mail
number written on the cover letter is also recommended. 
 (c) Deliver one copy of the completed election form to the Company. 

(d) Applicable state law may require that you attach a copy of the completed election form to your 201[_] state personal income tax return(s) when you
file it for the year (assuming you file a state personal income tax return).7 
 Please
consult your personal tax advisor(s) to determine whether or not a copy of this Section 83(b) election should be filed with your state personal income tax return(s). 

(e) Retain one copy of the completed election form for your personal permanent records. 

Note: An additional copy of the completed election form must be delivered to the transferee (recipient) of the property if the service provider
and the transferee are not the same person. 
 Please note that the election must be filed with the IRS within 30 days of the date of your restricted
stock grant. Failure to file within that time will render the election void and you may recognize ordinary taxable income as your vesting restrictions lapse. The Company and its counsel cannot assume responsibility for failure to file the election
in a timely manner under any circumstances. 
  

	6 	 Note: Per Treasury Regulation § 1.83-2(c), the
Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. As of October 2016, if you live in a foreign country or are a dual status alien (foreigners that will have lived both in their home
country and the United States during the year in which they make the election) you should send the 83(b) election to Austin, TX 73301-0215. You can verify this is still the correct address at: http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. 

	7 	 Note: Pursuant to Treasury Regulations finalized in July 2016 (Treas. Reg. § 1.83-2(c); T.D. 9779), taxpayers are no longer required to submit a copy of a Code Sec. 83(b) election with their federal personal income tax returns for the year in which the property subject to the
election was transferred. However, you are strongly encouraged to retain a copy of the completed election form and the IRS filed-stamped copy of your cover letter along with a copy of the federal personal income tax return for the year in which the
property subject to the election was transferred for your personal permanent records in case you ever need to demonstrate proper and timely filing (a common requirement imposed by acquirers in M&A transactions).

 SECTION 83(b) ELECTION 

____________, 201_ 
 Department of the Treasury

 Internal Revenue Service 
 [City, State Zip]8[Austin, TX 73301-0215 
 USA]9 

 

	Re:	 Election Under Section 83(b) 

Ladies and Gentlemen: 
 The undersigned taxpayer hereby elects,
pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended, to include in gross income as compensation for services the excess (if any) of the fair market value of the shares described below over the amount paid for those
shares. The following information is supplied in accordance with Treasury Regulation § 1.83-2: 
  

	1.	 The name, [social security number][taxpayer identification number], address of the undersigned, and the
taxable year for which this election is being made are: 

Name:                       
  ____________ 
 [Social Security Number][Tax Identification Number]:     ____________ 10 

Address:                ____________ 

                        
                               

Taxable year: Calendar year 201_.11 

 

	2.	 The property that is the subject of this election: [#] shares of common stock of [Company], a
[State] corporation (the “Company”). 

  

	3.	 The property was transferred on: [•], 201_. 

 

	8 	 Note: Per Treasury Regulation § 1.83-2(c),
the Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. Assuming these are individual taxpayers who would file a Form 1040, see http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. Use the address in the row which includes the state in which the service provider lives and in the column entitled “And you ARE NOT enclosing a payment”.

	9 	 Note: Per Treasury Regulation § 1.83-2(c),
the Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. As of October 2016, if you live in a foreign country or are a dual status alien (foreigners that will have lived both in their
home country and the United States during the year in which they make the election) you should send the 83(b) election to Austin, TX 73301-0215. You can verify this is still the correct address at: http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. 

	10 	 Note: If you do not have a taxpayer ID number (TIN), put “None –non-US taxpayer” and include in the cover letter to the IRS a statement explaining that the Section 83(b) election is being filed because the individual may become a US taxpayer before the stock
vests. If the individual is applying for a TIN, instead include “applied for” and enclose a copy of the W-7 application. Note that there may be important factors to consider before applying for a
TIN, including immigration status, etc. 

	11 	 Note: If an entity is the service provider, instead use “Fiscal year ending ___.”

	4.	 The property is subject to the following restrictions: Some or all of the shares are subject to
forfeiture or repurchase at less than their fair market value if the undersigned does not continue to provide services for the Company for a designated period of time. The risk of forfeiture or repurchase lapses over a specified vesting period.

  

	5.	 The fair market value of the property at the time of transfer (determined without regard to any restriction
other than a nonlapse restriction as defined in Treasury Regulation § 1.83-3(h)): $[•] per share x [#] shares = $[•]. 

 

	6.	 For the property transferred, the undersigned paid: $[•] per share x [#] shares = $[•].

  

	7.	 The amount to include in gross income is:
$[•].12 

 The undersigned taxpayer will file this election with the Internal
Revenue Service office with which taxpayer files his or her annual income tax return not later than 30 days after the date of transfer of the property. A copy of the election also will be furnished to the person for whom the services were performed
and the transferee of the property. Additionally, the undersigned will include a copy of the election with his or her income tax return for the taxable year in which the property is transferred. The undersigned is the person performing the services
in connection with which the property was transferred. 
  

	
	Very truly yours,
	
	  

	[Name]

  

	12 	 Note: This should equal the amount in Item 5 minus the amount in Item 6, and in many cases will
be $0.00. 

 RETURN SERVICE REQUESTED 

Department of the Treasury 
 Internal Revenue Service 

[City, State, ZIP][Austin, TX 73301-0215 
 USA] 

 

	Re:	 Election Under Section 83(b) of the Internal Revenue Code

 Dear Sir or Madam: 

Enclosed please find an executed form of election under Section 83(b) of the Internal Revenue Code of 1986, as amended, filed with respect
to an interest in TDTx, Inc. 
 [Please note, the undersigned does not currently have a Tax Identification Number because the undersigned is
not a U.S. taxpayer, but may become a U.S. resident before the stock vests. ] 
 Also enclosed is a copy of the signed form of election
under Section 83(b). Please acknowledge receipt of these materials by marking the copy when received and returning it in the enclosed stamped, self-addressed envelope. 

Thank you very much for your assistance. 
  

	
	Very truly yours,
	
	  

	[Name]

 Enclosures 

 TDTX INC. 

RESTRICTED STOCK AWARD GRANT NOTICE 

(2019 EQUITY INCENTIVE PLAN) 
 TDTx
Inc. (the “Company”), pursuant to its 2019 Equity Incentive Plan (the “Plan”), hereby awards to Participant, in consideration for Participant’s past or future services actually or to be
rendered to the Company, the number of shares of Common Stock (the “Shares”) set forth below (the “Award”). The Award is subject to all of the terms and conditions as set forth in this Restricted Stock
Award Grant Notice (the “Grant Notice”) and the attached Restricted Stock Award Terms and Conditions (together with the Grant Notice, the “Award Agreement”), and the Plan, all of which are attached to
this Grant Notice and incorporated into this Grant Notice in their entirety. Capitalized terms not explicitly defined in the Award Agreement but defined in the Plan will have the meanings provided in the Plan. If the Company uses an electronic
capitalization table system (such as Carta or Shareworks) and the fields below are blank or the information is otherwise provided in a different format electronically, the blank fields and other information (such as exercise schedule and type of
grant) shall be deemed to come from the electronic capitalization system and is considered part of this Grant Notice. 
  

			
	Participant:	  	                                     
                       
	Date of Grant:	  	                                     
                       
	Vesting Commencement Date:	  	                                     
                       
	Number of Shares Subject to Award:	  	                                     
                       
	Consideration:	  	[Participant’s services]

  

			
	Vesting Schedule:	  	[Sample of standard vesting. 12/48ths of the total shares will vest on the one-year anniversary of the Vesting Commencement Date, and 1/48th of the total shares will vest each month
thereafter on the same day of the month as the Vesting Commencement Date (or if there is no corresponding day, on the last day of the month), subject to Participant’s Continuous Service as of each such date].

 Additional Terms/Acknowledgements: Participant acknowledges receipt of a copy of the Plan and represents that he or she
is familiar with the terms and provisions thereof, and hereby accepts this Award subject to all of the terms and provisions of the Plan and this Award Agreement (including all attachments and exhibits) and has had an opportunity to obtain the advice
of counsel prior to executing and accepting the Award. By accepting this Award, Participant hereby agrees to accept as binding, conclusive and final all decisions or interpretations of the Board upon any questions arising under the Plan or this
Award. 
 Participant further consents to receive any documents related to the Plan by electronic delivery and to participate in the Plan through an online
or electronic system established and maintained by the Company or a third party designated by the Company. 
 Participant further acknowledges that as of
the Date of Grant, this Award Agreement and the Plan set forth the entire understanding between Participant and the Company regarding the acquisition of stock in the Company and supersede all prior oral and written agreements on that subject, with
the exception of (i) options, restricted stock awards or other compensatory stock awards previously granted and delivered to Participant, and (ii) any written employment or severance arrangement that would provide for vesting acceleration
of this Award upon the terms and conditions set forth therein. 

 Participant further acknowledges that this Award Agreement has been prepared on behalf of the Company by
Cooley LLP, counsel to the Company and that Cooley LLP does not represent, and is not acting on behalf of, Participant in any capacity. Participant has been provided with an opportunity to consult with Participant’s own counsel with respect to
this Award Agreement. 
 This Award may be executed in one or more counterparts, each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other
applicable law) or other transmission method and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

 

							
	TDTx Inc.	 		  	Participant:
				
	By:	 	  
	 		  	  

		 	Signature	 		  	Signature
	Title:	 	  
	 		  	Date:
                                         
       
	Date:	 	  
	 		  	

 Attachments: 
  

			
	Attachment I:	    	Restricted Stock Award Terms and Conditions
	Exhibit A:	    	Assignment Separate from Certificate
	Exhibit B :	    	Joint Escrow Instructions
		
	Attachment II:	    	2019 Equity Incentive Plan
	Attachment III:	    	Section 83(b) Election

 ATTACHMENT I 

RESTRICTED STOCK AWARD TERMS AND CONDITIONS 

 TDTX INC. 

(2019 EQUITY INCENTIVE PLAN) 

RESTRICTED STOCK AWARD TERMS AND CONDITIONS 

TDTx Inc. (the “Company”) has awarded you, in exchange for your services to the Company, the number of Shares
indicated in the Grant Notice (the “Award”) pursuant to its 2019 Equity Incentive Plan (the “Plan”). The Grant Notice and these Restricted Stock Award Terms and Conditions are collectively referred to
as the “Award Agreement”. Capitalized terms not explicitly defined in this Agreement but defined in the Plan will have the same meanings given to them in the Plan. 

The details of your Award, in addition to those set forth in the Grant Notice and the Plan, are as follows: 

1. Escrow of Shares. As security for your faithful performance of the terms of this Award Agreement and to ensure the availability for
delivery of the Unvested Shares upon exercise of the Reacquisition Right, you agree that the Shares will be held in escrow pursuant to the terms of the Joint Escrow Instructions attached to this Agreement as Exhibit B. You agree to execute
and deliver to the individual designated as the escrow agent in the Joint Escrow Instructions or person’s designee (the “Escrow Agent”), (i) the Joint Escrow Instructions and (ii) two Assignment Separate From
Certificate forms duly endorsed (with date and number of shares blank) substantially in the form attached to this Agreement as Exhibit A and deliver the same, along with the certificate or certificates evidencing the Unvested Shares, which
will be held and used by the Escrow Agent pursuant to the terms of the Joint Escrow Instructions. 
 2. Vesting. Subject to the
limitations contained herein, the Shares will vest pursuant to the Vesting Schedule in the Grant Notice, provided that vesting will cease upon the termination of your Continuous Service. “Vested Shares” will mean Shares that
have vested in accordance with the Vesting Schedule, and “Unvested Shares” will mean Shares that have not vested in accordance with the Vesting Schedule. 

3. Number of Shares; Capitalization Adjustments. The number of Shares subject to your Award may be adjusted from time to time for
Capitalization Adjustments. In the event of any such Capitalization Adjustments, new, substituted or additional securities or other property to which you are entitled by reason of your ownership of the Unvested Shares will be immediately subject to
the same vesting requirements and vesting schedule that is applicable to the Shares with respect to which such additional Shares relate, as well as all transfer restrictions contained in this Award Agreement, including the Reacquisition Right, the
Right of First Refusal and the Lock-Up Period (each as defined below). No fractional shares or rights for fractional shares will be created pursuant to this Section. Any fraction of a share will be rounded
down to the nearest whole share. 
 4. Securities Law Compliance. The Shares are not registered under the Securities Act. At this
time, the Company has determined that the issuance of the Shares under this Award is exempt from the registration requirements of the Securities Act. If the Company determines at any time that an exemption from the registration requirements of the
Securities Act was not available or that the issuance of the Shares otherwise would not comply with any other applicable laws and regulations, then the Company will not be obligated to issue the Shares or may rescind the award to you. 

  
 1 

 5. Transfer Restrictions. In addition to any other limitation on transfer
created by the Company’s bylaws and applicable securities laws, you may not Transfer all or any part of the Unvested Shares or any interest in the Unvested Shares while such shares are subject to the Reacquisition Right (as defined below) or
continue to be held by the Escrow Agent (as defined below) or by the Company’s transfer agent in restricted book entry form. In the case of Vested Shares, you may not Transfer the Vested Shares or any interest in the Vested Shares except in
compliance with this Award Agreement, including without limitation the Right of First Refusal (as defined below), the Company’s bylaws and applicable securities laws. As used in this Award Agreement, the term “Transfer”
means any sale, encumbrance, pledge, gift or other form of disposition or transfer of shares of Common Stock or any legal or equitable interest therein; provided, however, that the term Transfer does not include a transfer of such shares or
interests by will or intestacy to your Immediate Family. In such case, the transferee or other recipient will receive and hold the Shares so transferred subject to the provisions of this Award Agreement, and there will be no further transfer of such
shares except in accordance with the terms of this Award Agreement. The term “Immediate Family” will mean your spouse, the lineal descendant or antecedent, father, mother, brother or sister, child, adopted child, grandchild
or adopted grandchild of you or your spouse, or the spouse of any child, adopted child, grandchild or adopted grandchild of you or your spouse. 

6. Unvested Share Reacquisition Right. 

(a) Reacquisition Right. In the event your Continuous Service terminates, the Company will automatically reacquire (the
“Reacquisition Right”) on the date that is 90 days after the termination of your Continuous Service (the “Reacquisition Date”) all Unvested Shares as of the date of your termination of Continuous
Service without any payment to you (that is, for zero dollars ($0)) and without any required action or notice to you. You hereby agree to take whatever action the Company deems necessary to effectuate the Company’s reacquisition of the Unvested
Shares. Following such reacquisition, the Company will become the legal and beneficial owner of the Unvested Shares being reacquired and all rights and interests in and related to such shares, and the Company will have the right to transfer to its
own name the Unvested Shares being reacquired by the Company without further action by you. Notwithstanding anything to the contrary in this Section or in this Award Agreement, the Company may elect to waive, in its sole discretion, its
Reacquisition Right in whole or in part by providing written notice to you (with a copy to the Escrow Agent, as defined below), at any time prior to or on the Reacquisition Date, and the Escrow Agent may then release to you the number of Shares not
being reacquired by the Company. 
 (b) Corporate Transactions. To the extent the Reacquisition Right remains in effect following a
Corporate Transaction or Change in Control, unless otherwise provided by the Board pursuant to the terms of the Plan, it will apply to the new capital stock, cash or other property received in exchange for the Unvested Shares in consummation of the
Corporate Transaction or Change in Control, as applicable, but only to the extent the Unvested Shares were at the time covered by such right. 

(c) Termination of Reacquisition Right. The Company’s Reacquisition Right will terminate upon the earlier of (i) the
Company’s reacquisition in full of the Unvested Shares (or waiver of the Reacquisition Right) and (ii) the expiration of the Company’s Reacquisition Right. 

7. Right of First Refusal. Shares that are received under your Award are subject to any right of first refusal that may be
described in the Company’s bylaws in effect at such time the Company elects to exercise its right; provided, however, that if there is no right of first refusal described in the Company’s bylaws at such time, the right of first
refusal described below (the “Right of First Refusal”) will apply. The Right of First Refusal will expire on the first date upon which any security of the Company is listed (or approved for listing) upon notice of issuance on
a national securities exchange or quotation system (the “Listing Date”). 

  
 2 

 (a) Prior to the Listing Date, you may not validly Transfer any Shares received under
the Award, or any interest in such shares, unless such Transfer is made in compliance with the following provisions: 
 (i) Before
there can be a valid Transfer of any Shares or any interest therein, the record holder of the Shares to be transferred (the “Offered Shares”) will give written notice (by registered or certified mail) to the Company (the
“ROFR Notice”). Such notice will specify the identity of the proposed transferee, the cash price offered for the Offered Shares by the proposed transferee (or, if the proposed Transfer is one in which the holder will not
receive cash, such as an involuntary transfer, gift, donation or pledge, the holder will state that no purchase price is being proposed), and the other terms and conditions of the proposed Transfer. The date such notice is mailed will be hereinafter
referred to as the “Notice Date” and the record holder of the Offered Shares will be hereinafter referred to as the “Offeror.” 

(ii) For a period of 30 calendar days after the Notice Date, the Company will have the option to exercise its Right of First Refusal
and purchase all or any portion of the Offered Shares at the purchase price and on the terms set forth in this Section. In the event that the proposed Transfer is one involving no payment of a purchase price, the purchase price will be deemed to be
the Fair Market Value of the Offered Shares as determined in good faith by the Board in its discretion. The Company may exercise its Right of First Refusal by mailing (by registered or certified mail) written notice of exercise of its Right of First
Refusal to the Offeror prior to the end of said 30 days. 
 (iii) The price at which the Company may purchase the Offered Shares
pursuant to the exercise of its Right of First Refusal will be the cash price offered for the Offered Shares by the proposed transferee (as set forth in the ROFR Notice), or the Fair Market Value as determined by the Board in the event no purchase
price is involved. To the extent consideration other than cash is offered by the proposed transferee, the Company will not be required to pay any additional amounts to the Offeror other than the cash price offered (or the Fair Market Value, if
applicable). The Company’s notice of exercise of its Right of First Refusal will be accompanied by full payment for the Offered Shares and, upon such payment by the Company, the Company will acquire full right, title and interest to all of the
Offered Shares. 
 (iv) If, and only if, the Company elects not to exercise its Right of First Refusal as to the Offered Shares, the
Transfer proposed in the ROFR Notice may take place; provided, however, that such Transfer must, in all respects, be exactly as proposed in said notice except that such Transfer may not take place either before the 10th calendar day after the expiration of the 30 day option exercise period or after the 90th calendar day after the expiration of the 30 day option
exercise period, and if such Transfer has not taken place prior to said 90th day, such Transfer may not take place without once again complying with this Section. 

(b) None of the shares of Common Stock received under the Award will be transferred on the Company’s books nor will the Company
recognize any such Transfer of any such shares or any interest therein unless and until all applicable provisions of this Section have been complied with in all respects. The certificates of stock evidencing Shares received under the Award will bear
an appropriate legend referring to the transfer restrictions imposed by this Section. 
 8.
Lock-Up Period. By accepting your Award, you agree that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or
similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held by you, for a period of 180 days following the effective date of a registration statement of the Company
filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with applicable FINRA rules (the “Lock-Up Period”);

  
 3 

 
provided, however, that nothing contained in this Section will prevent the exercise of a reacquisition or repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or that are necessary to give
further effect to the foregoing covenant. You also agree that any transferee of any other shares of Common Stock (or other securities) of the Company held by you will be bound by this Section. To enforce the foregoing covenant, the Company may
impose stop-transfer instructions with respect to your shares of Common Stock until the end of such period. The underwriters of the Company’s stock are intended third party beneficiaries of this Section and will have the right, power and
authority to enforce the provisions of this Section as though they were a party to this Award Agreement. You further agree that the obligations contained in this Section 8 shall also, if so determined by the Company’s Board of Directors,
apply in the Company’s initial listing of its Common Stock on a national securities exchange by means of a registration statement on Form S-1 under the Securities Act (or any successor registration form
under the Securities Act subsequently adopted by the Securities and Exchange Commission) filed by the Company with the Securities and Exchange Commission that registers shares of existing capital stock of the Company for resale (a “Direct
Listing”) (and, for avoidance of doubt, the Lock-Up Period shall be deemed to include the period following the Direct Listing during which the restrictions under this Section 8 apply)
provided that all holders of at least 5% of the Company’s outstanding Common Stock (after giving effect to the conversion into Common Stock of any outstanding Preferred Stock of the Company) are subject to substantially similar obligations with
respect to such Direct Listing. 
 9. Rights as Stockholder. 

(a) General. Subject to the provisions of this Award Agreement, you will exercise all rights and privileges of a stockholder of the
Company with respect to the Shares, including for purposes of exercising any voting rights relating to any Unvested Shares. 
 (b)
Dividends. You will be deemed to be the holder of the Unvested Shares for purposes of receiving any dividends that may be paid with respect to such Shares; provided, however, that any dividends or other distributions paid with respect to
the Unvested Shares shall be subject to all of the terms and conditions applicable under this Award Agreement to the same extent as the Unvested Shares. For clarity, cash dividends made prior to the vesting of any Unvested Shares will be withheld
and paid to you (without interest) only if, when and to the extent, such Shares become Vested Shares. 
 10. Waiver of
Information Rights. You hereby acknowledge and agree that, except for such information as required to be delivered to you by the Company pursuant to any other agreement by and between you and the Company, you shall have no right to receive any
information from the Company by virtue of your purchase of the Shares, ownership of the Shares, or as a result of you being a holder of record of stock of the Company. Without limiting the foregoing, to the fullest extent permitted by law, you
hereby waive your inspection rights under Section 220 of the Delaware General Corporation Law and all such similar information and/or inspection rights that may be provided under the law of any jurisdiction, or any federal, state or foreign
regulation, that are, or may become, applicable to the Company, the Company’s capital stock or the Shares (the “Inspection Rights”). You hereby covenant and agree never to directly or indirectly commence,
voluntarily aid in any way, prosecute, assign, transfer, or cause to be commenced any claim, action, cause of action, or other proceeding to pursue or exercise the Inspection Rights. 

  
 4 

 11. Restrictive Legends. All certificates representing the Common Stock
issued under your Award will be endorsed with appropriate legends determined by the Company in substantially the following forms (in addition to any other legend that may be required by other agreements between you and the Company): 

(a) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A REACQUISITION RIGHT AND OTHER RESTRICTIONS AND CONDITIONS SET
FORTH IN A RESTRICTED STOCK AWARD AGREEMENT BETWEEN THE COMPANY AND THE REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE COMPANY’S PRINCIPAL CORPORATE OFFICES. ANY TRANSFER OR ATTEMPTED
TRANSFER OF ANY SHARES SUBJECT TO SUCH RIGHT IS VOID WITHOUT THE PRIOR EXPRESS WRITTEN CONSENT OF THE COMPANY.” 
 (b) “THE
SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES
UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.” 
 (c) “THE
SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RIGHTS OF REFUSAL GRANTED TO THE COMPANY AND/OR ITS ASSIGNEE(S) AND ACCORDINGLY MAY NOT BE SOLD, ASSIGNED, TRANSFERRED, ENCUMBERED OR IN ANY MANNER DISPOSED OF EXCEPT IN CONFORMITY WITH
THE TERMS OF THE BYLAWS OF THE COMPANY AND/OR A RESTRICTED STOCK AWARD AGREEMENT BETWEEN THE COMPANY AND THE REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE COMPANY’S PRINCIPAL CORPORATE
OFFICES.” 
 (d) “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A TRANSFER RESTRICTION, AS PROVIDED IN THE
BYLAWS OF THE COMPANY.” 
 (e) Any legend required by appropriate blue sky officials. 

12. Investment Representations. In connection with your acquisition of the Common Stock under your Award, you represent to
the Company the following: 
 (a) You are aware of the Company’s business affairs and financial condition and have acquired
sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Shares. You are acquiring the Shares for investment for your own account only and not with a view to, or for resale in connection with, any
“distribution” thereof within the meaning of the Securities Act. 
 (b) You understand that the Shares have not been
registered under the Securities Act by reason of a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of your investment intent as expressed in this Award Agreement. 

(c) You further acknowledge and understand that the Shares must be held indefinitely unless the Shares are subsequently registered under
the Securities Act or an exemption from such registration is available. You further acknowledge and understand that the Company is under no obligation to register the Common Stock. You understand that the certificate evidencing the Common Stock will
be imprinted with a legend that prohibits the transfer of the Common Stock unless the Common Stock is registered or such registration is not required in the opinion of counsel for the Company. 

  
 5 

 (d) You are familiar with the provisions of Rule 701 and Rule 144 promulgated
under the Securities Act (“Rule 144”), as in effect from time to time, which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from
an affiliate of such issuer), in a non-public offering subject to the satisfaction of certain conditions. Rule 701 provides that if the issuer qualifies under Rule 701 at the time of issuance of the
securities, such issuance will be exempt from registration under the Securities Act. In the event the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Exchange Act, the securities exempt under Rule 701
may be sold by you 90 days thereafter, subject to the satisfaction of certain of the conditions specified by Rule 144 and by the agreement(s) relating to the Lock-Up Period. 

(e) In the event that the sale of the Shares does not qualify under Rule 701 at the time of issuance, then the Shares may be resold
by you in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company; and (ii) the resale occurring following the required
holding period under Rule 144 after you have purchased, and made full payment of (within the meaning of Rule 144), the securities to be sold. 

(f) You further understand that at the time you wish to sell the Shares, there may be no public market upon which to make such a sale,
and that, even if such a public market then exists, the Company may not be satisfying the current public current information requirements of Rule 144 or 701, and that, in such event, you would be precluded from selling the Shares under Rule 144 or
701 even if the minimum holding period requirement had been satisfied. 
 13. Withholding Obligations. 

(a) At the time your Award is made, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll
and any other amounts payable to you, and otherwise agree to make adequate provision for any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection
with your Award (the “Withholding Taxes”). The Company may, in its sole discretion, satisfy all or any portion of the Withholding Taxes obligation relating to your Award by any of the following means or by a combination of
such means: (i) withholding from any amounts otherwise payable to you by the Company; (ii) causing you to tender a cash payment; or (iii) withholding Shares issued or otherwise issuable to you in connection with the Award with a Fair
Market Value equal to the amount of such Withholding Taxes; provided, however, that the number of such Shares withheld may not exceed the amount necessary to satisfy the Company’s required tax withholding obligations using the minimum
statutory withholding rates for federal, state, local and foreign tax purposes, including payroll taxes, that are applicable to supplemental taxable income. 

(b) Unless the tax withholding obligations of the Company and any Affiliate are satisfied, the Company will have no obligation to issue
a certificate for such Shares or release such Shares from any escrow provided for in this Award Agreement. 
 14. Tax Consequences.
You agree to review with your own tax advisors the federal, state, local and foreign tax consequences of this investment and the transactions contemplated by this Award. You will rely solely on such advisors and not on any statements or
representations of the Company or any of its agents. You understand that you (and not the Company) will be responsible for your own tax liability that may arise as a result of this investment or the transactions contemplated by this Award. You
understand that Section 83 of the Code taxes as ordinary income to you the fair market value of the Shares issued to you pursuant to the Award as of the date any restrictions on such shares lapse (that is, as of the date on which part or all of
such shares vest). In this context, “restriction” includes the right of the Company to reacquire the Shares pursuant to the Reacquisition Right set forth above. You understand that you may elect to be taxed at the time the Shares are
issued to you pursuant to your Award, rather than when and as the Reacquisition Right expires, by filing an election under Section 83(b) of the Code (an “83(b) Election”)

  
 6 

 
with the Internal Revenue Service within 30 days after the date your acquire Shares pursuant to your Award. Even if the fair market value of the Common Stock at the time of grant of your Award
equals the amount paid for the Shares (if anything), the 83(b) Election must be made to avoid income under Section 83(a) in the future. You understand that failure to file such an 83(b) Election in a timely manner may result in adverse tax
consequences for you. You acknowledge that the foregoing is only a summary of the effect of U.S. federal income taxation with respect to issuance of the Shares pursuant to your Award, and does not purport to be complete. You further acknowledge that
the Company has directed you to seek independent advice regarding the applicable provisions of the Code, the income tax laws of any municipality, state or foreign country in which you may reside, and the tax consequences of your death. You assume
all responsibility for filing an 83(b) Election and paying all taxes resulting from such election or the lapse of the restrictions on the Shares. YOU ACKNOWLEDGE THAT IT IS YOUR OWN RESPONSIBILITY, AND NOT THE COMPANY’S, TO FILE A TIMELY
83(b) ELECTION. THE COMPANY AND ITS LEGAL COUNSEL CANNOT ASSUME RESPONSIBILITY FOR FAILURE TO FILE THE 83(b) ELECTION IN A TIMELY MANNER UNDER ANY CIRCUMSTANCES. 

15. Severability. If all or any part of this Award Agreement or the Plan is declared by any court or governmental authority to be
unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Award Agreement or the Plan not declared to be unlawful or invalid. Any Section of this Award Agreement (or part of such a Section) so declared to be
unlawful or invalid shall, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid. 

16. Governing Law. The interpretation, performance and enforcement of this Award Agreement shall be governed by the law of the State of
Delaware without regard to that state’s conflicts of laws rules. 
 17. Notices. Any notice or request required or
permitted hereunder will be given in writing to each of the other parties hereto and will be deemed effectively given on the earlier of (i) the date of personal delivery, including delivery by express courier, or delivery via electronic means,
or (ii) the date that is five days after deposit in the United States Post Office (whether or not actually received by the addressee), by registered or certified mail with postage and fees prepaid, addressed to the Company at its primary
executive offices, attention: Stock Plan Administrator, and addressed to you at your address as on file with the Company at the time notice is given. 

18. Imposition of Other Requirements. As a condition to the grant of your Award or to the Company’s the issuance of any
Shares under this Award, the Company may require you to execute further documents or instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your Award. In addition, you may be required to
execute certain customary agreements entered into with the holders of capital stock of the Company, including without limitation a right of first refusal and co-sale agreement, stockholders agreement and a
voting agreement. 

  
 7 

 EXHIBIT A TO 

RESTRICTED STOCK AWARD TERMS AND CONDITIONS 

ASSIGNMENT SEPARATE FROM CERTIFICATE 

For Value Received and pursuant to that certain Restricted Stock Award Grant Notice dated ____________ (the
“Award”), [Participant’s Name] hereby sells, assigns and transfers unto TDTx Inc., a Delaware corporation (the “Company”) _______________ shares of the Common Stock of the
Company, standing in the undersigned’s name on the books of the Company represented by Certificate No(s). _____ and does hereby irrevocably constitute and appoint the Company’s Secretary as attorney-in-fact to transfer the said Common Stock on the books of the Company with full power of substitution in the premises. This Assignment Separate From Certificate may be used only in accordance
with and subject to the terms and conditions of the Award, in connection with the reacquisition of shares of Common Stock of the Company issued to the undersigned pursuant to the Award, and only to the extent that such shares remain subject to
the Company’s Reacquisition Right under the Award. 
 Dated:
                     
  

	
	  

	(Signature)
	
	  

	(Print Name)

 Instructions: Please do not fill in any blanks other than the “Signature” line and the “Print
Name” line. 

 EXHIBIT B TO 

RESTRICTED STOCK AWARD TERMS AND CONDITIONS 

JOINT ESCROW INSTRUCTIONS 
 Secretary 

TDTx Inc. 
  

 
  

Dear Sir or Madam: 
 As Escrow Agent for both
TDTx Inc., a Delaware corporation (the “Company”), and the undersigned recipient (“Recipient”) of Common Stock of the Company (the “Common Stock”), you are hereby
authorized and directed to hold the documents delivered to you pursuant to the terms of the Restricted Stock Award Grant Notice (including all attachments and exhibits) dated ___________________ (the “Award”), to which a copy
of these Joint Escrow Instructions is attached as Exhibit B to the Restricted Stock Award Terms and Conditions (the “Agreement”, in accordance with the following instructions: 

1. In the event Recipient ceases to render services to the Company or an affiliate of the Company during the vesting period set forth in
the Grant Notice, the Company or its affiliate or assignee, as applicable, will give to Recipient and you a written notice specifying the number of shares of Common Stock that will be transferred to the Company. Recipient and the Company hereby
irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of said notice. 

2. At the closing you are directed (a) to date any stock assignments necessary for the transfer in question, (b) to fill in
the number of shares of Common Stock being transferred, and (c) to deliver the same, together with the certificate evidencing the shares of Common Stock to be transferred, to the Company. 

3. Recipient irrevocably authorizes the Company to deposit with you any certificates evidencing shares of Common Stock to be held by you
hereunder and any additions and substitutions to said shares of Common Stock as specified in the Grant Notice and the Agreement. Recipient does hereby irrevocably constitute and appoint you as Recipient’s attorney-in-fact and agent for the term of this escrow to execute with respect to such securities and other property all documents of assignment and/or transfer and all stock certificates necessary or
appropriate to make all securities negotiable and complete any transaction herein contemplated. 
 4. This escrow will terminate and
the shares of Common Stock held hereunder will be released in full upon the full vesting of the shares of Common Stock in accordance with the vesting schedule set forth in the Grant Notice or upon the earlier return of the shares of Common Stock to
the Company pursuant to the Company’s Reacquisition Right (as defined in the Agreement) or other forfeiture condition under the Company’s 2019 Equity Incentive Plan. 

5. If at the time of termination of this escrow you should have in your possession any documents, securities, or other property
belonging to Recipient, you will deliver all of same to Recipient and will be discharged of all further obligations hereunder; provided, however, that if at the time of termination of this escrow you are advised by the Company that the
property subject to this escrow is the subject of a pledge or other security agreement, you will deliver all such property to the pledgeholder or other person designated by the Company. 

 6. Except as otherwise provided in these Joint Escrow Instructions, your duties
hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties hereto. 
 7. You will be
obligated only for the performance of such duties as are specifically set forth herein and may rely and will be protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or
presented by the proper party or parties or their assignees. You will not be personally liable for any act you may do or omit to do hereunder as Escrow Agent or as
attorney-in-fact for Recipient while acting in good faith and any act done or omitted by you pursuant to the advice of your own attorneys will be conclusive evidence of
such good faith. 
 8. You are hereby expressly authorized to disregard any and all warnings given by any of the parties hereto or by
any other person or corporation, excepting only orders or process of courts of law, and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. In case you obey or comply with any such order, judgment or
decree of any court, you will not be liable to any of the parties hereto or to any other person, firm or corporation by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled,
set aside, vacated or found to have been entered without jurisdiction. 
 9. You will not be liable in any respect on account of the
identity, authority or rights of the parties executing or delivering or purporting to execute or deliver the Grant Notice, the Agreement or any documents or papers deposited or called for hereunder. 

10. You will not be liable for the outlawing of any rights under any statute of limitations with respect to these Joint Escrow
Instructions or any documents deposited with you. 
 11. Your responsibilities as Escrow Agent hereunder will terminate if you cease
to be Secretary of the Company or if you resign by written notice to the Company. In the event of any such termination, the Secretary of the Company will automatically become the successor Escrow Agent unless the Company appoints another successor
Escrow Agent and Recipient hereby confirms the appointment of such successor as Recipient’s attorney-in-fact and agent to the full extent of your appointment. 

12. If you reasonably require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect
hereto, the necessary parties hereto will join in furnishing such instruments. 
 13. It is understood and agreed that should any
dispute arise with respect to the delivery and/or ownership or right of possession of the securities, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities until such dispute has
been settled either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but you will be under no
duty whatsoever to institute or defend any such proceedings. 
 14. Any notice or request required or permitted hereunder will be
given in writing to each of the other parties hereto and will be deemed effectively given on the earlier of (i) the date of personal delivery, including delivery by express courier, or delivery via electronic means, or (ii) the date that
is five days after deposit in the United States Post Office (whether or not actually received by the addressee), by registered or certified mail with postage and fees prepaid, addressed to each of the other parties hereunto entitled at the following
addresses, or at such other addresses as a party may designate by 10 days’ advance written notice to each of the other parties hereto: 

 
			
	Company:	  	 TDTx Inc.

		  	
                   
                                 

		  	
                   
                                 

		  	
                   
                                 

		  	 Attn: General Counsel / Chief Financial Officer

		
	Recipient:	  	
                   
                                 

		  	
                   
                                 

		  	
                   
                                 

		  	
                   
                                 

		
	Escrow Agent:	  	 TDTx Inc.

		  	
                   
                                 

		  	
                   
                                 

		  	
                   
                                 

		  	 Attn: Corporate Secretary

 15. By signing these Joint Escrow Instructions you become a party hereto only for the purpose of
said Joint Escrow Instructions; you do not become a party to the Grant Notice or the Agreement. 
 16. You are entitled to employ such
legal counsel, including without limitation Cooley LLP, and other experts as you may deem necessary to advise you in connection with your obligations hereunder. You may rely upon the advice of such counsel, and may pay such counsel reasonable
compensation therefor. The Company will be responsible for all fees generated by such legal counsel in connection with your obligations hereunder. 

17. This instrument will be binding upon and inure to the benefit of the parties hereto, and their respective successors and permitted
assigns. It is understood and agreed that references to “you” or “your” herein refer to the original Escrow Agent and to any and all successor Escrow Agents. It is understood and agreed that the Company may at any time or from
time to time assign its rights under the Grant Notice, the Agreement and these Joint Escrow Instructions in whole or in part. 

[Remainder of page intentionally left blank] 

 18. These Joint Escrow Instructions will be governed by and interpreted and determined in
accordance with the laws of the State of Delaware without regard to that state’s conflicts of laws rules. The parties hereby expressly consent to the personal jurisdiction of the state and federal courts located in the county in which the
Company has its principal offices for any lawsuit arising from or related to this Agreement. 
  

			
	Very truly yours,
	
	TDTx Inc.
		
	By	 	  

	Title	 	  

	
	Recipient
	
	  

	(Signature)
	
	  

	(Print Name)

  

	
	Escrow Agent:
	
	  

	(Signature)
	
	  

 (Print Name) 

 ATTACHMENT II 

2019 EQUITY INCENTIVE PLAN 

 ATTACHMENT III 

SECTION 83(B) ELECTION 

 [This Form is designed for Individual purchasers. Corporate or Trust purchasers should
contact their Tax Professional to review before submitting.] 
 Instructions for Filing Section 83(b) Election 

Attached is a form of election under Section 83(b) of the Internal Revenue Code and an accompanying IRS cover letter. Please complete and
sign the election and cover letter, then proceed as follows: 
  

	 	a)	 Make three copies of the completed election form and one copy of the IRS cover letter.

  

	 	b)	 Send the original signed election form and cover letter, the copy of the cover letter, and
a self-addressed stamped return envelope to the Internal Revenue Service Center where you would otherwise file your tax return.1 Even if an address for an Internal Revenue Service Center is
already included in the forms below, it is your obligation to verify such address. This can be done by searching for the term “where to file” on www.irs.gov or by calling 1 (800) 829-1040.

 Sending the election via certified mail, requesting a return receipt, with the certified mail number written on the
cover letter is also recommended. 
  

	 	c)	 Deliver one copy of the completed election form to the Company. 

 

	 	d)	 Applicable state law may require that you attach a copy of the completed election form to your state
personal income tax return(s) when you file it for the year (assuming you file a state personal income tax return).2 

Please consult your personal tax advisor(s) to determine whether or not a copy of this Section 83(b) election should be filed with your
state personal income tax return(s). 
  

	 	e)	 Retain one copy of the completed election form for your personal permanent records.

 Note: An additional copy of the completed election form must be delivered to the transferee (recipient) of the property if the service
provider and the transferee are not the same person. 
 Please note that the election must be filed with the IRS within 30 days of the date of
purchase/grant of the shares. Failure to file within that time will render the election void and you may recognize ordinary taxable income as your vesting restrictions lapse. The Company and its counsel cannot assume responsibility for failure
to file the election in a timely manner under any circumstances. 
  

	1 	 Note: Per Treasury Regulation § 1.83-2(c), the
Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. As of September 2018 if you live in a foreign country or are a dual status alien (foreigners that will have lived both in their
home country and the United States during the year in which they make the election) you should send the 83(b) election to Austin, TX 73301-0215. You can verify this is still the correct address at: http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. 

	2 	 Note: Pursuant to Treasury Regulations finalized in July 2016 (Treas. Reg. § 1.83-2(c); T.D. 9779), taxpayers are no longer required to submit a copy of a Code Sec. 83(b) election with their federal personal income tax returns for the year in which the property subject to the
election was transferred. However, you are strongly encouraged to retain a copy of the completed election form and the IRS filed-stamped copy of your cover letter along with a copy of the federal personal income tax return for the year in which the
property subject to the election was transferred for your personal permanent records in case you ever need to demonstrate proper and timely filing (a common requirement imposed by acquirers in M&A transactions).

 SECTION 83(b) ELECTION 

____________, 20_ 
 Department of the Treasury

 Internal Revenue Service 
 [City, State Zip]3[Austin, TX 73301-0215 
 USA]4 

Re: Election Under Section 83(b) 
 Ladies and Gentlemen:

 The undersigned taxpayer hereby elects, pursuant to Section 83(b) of the Internal Revenue Code of 1986, as amended, to include in gross income as
compensation for services the excess (if any) of the fair market value of the shares described below over the amount paid for those shares. The following information is supplied in accordance with Treasury Regulation § 1.83-2: 
  

	1.	 The name, [social security number][taxpayer identification number], address of the undersigned, and the
taxable year for which this election is being made are: 

Name:                       
  ____________ 
 [Social Security Number][Tax Identification Number]: ____________
5 

Address:                ____________ 

                        
                                   

Taxable year: Calendar year ______.6 

 

	2.	 The property that is the subject of this election: [#] shares of common stock of TDTx Inc., a
Delaware corporation (the “Company”). 

  

	3.	 The property was transferred on: [•]. 

 

	4.	 The property is subject to the following restrictions: Some or all of the shares are subject to
forfeiture or repurchase at less than their fair market value if the undersigned does not continue to provide services for the Company for a designated period of time. The risk of forfeiture or repurchase lapses over a specified vesting period.

  

	3 	 Note: Per Treasury Regulation § 1.83-2(c),
the Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. Assuming these are individual taxpayers who would file a Form 1040, see http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. Use the address in the row which includes the state in which the service provider lives and in the column entitled “And you ARE NOT enclosing a payment”.

	4 	 Note: Per Treasury Regulation § 1.83-2(c),
the Section 83(b) election must be filed with the IRS office where the person otherwise files his or her tax return. As of December 2018, if you live in a foreign country or are a dual status alien (foreigners that will have lived both in their
home country and the United States during the year in which they make the election) you should send the 83(b) election to Austin, TX 73301-0215. You can verify this is still the correct address at: http://www.irs.gov/uac/Where-to-File-Addresses-for--Taxpayers-and--Tax-Professionals-Filing-Form-1040
. 

	5 	 Note: If you are not a US taxpayer and do not have a taxpayer ID number (TIN), put “None –non-US taxpayer” and include in the cover letter to the IRS a statement explaining that the Section 83(b) election is being filed because the individual may become a US taxpayer before the stock
vests. If the individual is applying for a TIN, instead include “applied for” and enclose a copy of the W-7 application. Note that there may be important factors to consider before applying for a
TIN, including immigration status, etc. 

	6 	 Note: If an entity is the service provider, instead use “Fiscal year ending ___.”

	5.	 The fair market value of the property at the time of transfer (determined without regard to any restriction
other than a nonlapse restriction as defined in Treasury Regulation § 1.83-3(h)): $[•] per share x [#] shares = $[•]. 

 

	6.	 For the property transferred, the undersigned paid: $[•] per share x [#] shares = $[•].

  

	7.	 The amount to include in gross income is:
$[•].7 

 The undersigned taxpayer will file this election with the Internal
Revenue Service office with which taxpayer files his or her annual income tax return not later than 30 days after the date of transfer of the property. A copy of the election also will be furnished to the person for whom the services were performed
and the transferee of the property. Additionally, the undersigned will include a copy of the election with his or her income tax return for the taxable year in which the property is transferred. The undersigned is the person performing the services
in connection with which the property was transferred. 
  

	
	Very truly yours,
	
	  

	[Name]

  

	7 	 Note: This should equal the amount in Item 5 minus the amount in Item 6, and in many cases will
be $0.00. 

 RETURN SERVICE REQUESTED 

Department of the Treasury 
 Internal Revenue Service 

[City, State, ZIP][Austin, TX 73301-0215 
 USA] 

 

	Re:	 Election Under Section 83(b) of the Internal Revenue Code

 Dear Sir or Madam: 

Enclosed please find an executed form of election under Section 83(b) of the Internal Revenue Code of 1986, as amended, filed with respect
to an interest in TDTx Inc. 
 [Please note, the undersigned does not currently have a Tax Identification Number because the undersigned is
not a U.S. taxpayer, but may become a U.S. resident before the stock vests.] 
 Also enclosed is a copy of the signed form of election under
Section 83(b). Please acknowledge receipt of these materials by marking the copy when received and returning it in the enclosed stamped, self-addressed envelope. 

Thank you very much for your assistance. 
  

	
	Very truly yours,
	
	  

	[Name]

 Enclosures 

 FIRST AMENDMENT TO THE

 AFFINIA THERAPEUTICS INC. 

2019 EQUITY INCENTIVE PLAN 

A. Affinia Therapeutics Inc. (f/k/a TDTx Inc.), a Delaware corporation (the “Company”)
established the Company’s 2019 Equity Incentive Plan by an original instrument adopted by the Company on November 25, 2019 (the “Plan”); 

B. The Plan currently provides for 1,200,000 shares (after giving effect to the stock split effected by the Amended and
Restated Certificate of Incorporation of the Company filed with the Secretary of State of the State of Delaware on the date hereof (the “Stock Split”)) of Common Stock to be reserved for issuance under the Plan; and 

C. The Company now wishes to amend the Plan to increase the number of shares of Common Stock reserved under the plan to
7,062,006 shares. 
 Effective immediately following the Stock Split, the Plan is amended as follows: 

 

	 	1.	 Section 3(a)(i) the Plan is hereby amended and restated in its entirety as follows: 

“Subject to Section 9(a) relating to Capitalization Adjustments, the aggregate number of shares of Common Stock that may be issued
pursuant to Stock Awards from and after the Effective Date will not exceed 7,062,006 shares (the “Share Reserve”).” 
  

	 	2.	 In all other respects, the Plan remains the same. 

[SIGNATURE PAGE FOLLOWS] 

 The Company has caused this First Amendment to the Company’s 2019 Equity Incentive Plan
to be executed this 12th day of March, 2020. 
  

			
	AFFINIA THERAPEUTICS INC.
		
	By:	 	 /s/ Rick Modi

		 	Rick Modi
		 	Chief Executive Officer

 SECOND AMENDMENT TO THE

 AFFINIA THERAPEUTICS INC. 

2019 EQUITY INCENTIVE PLAN 

A. Affinia Therapeutics Inc., a Delaware corporation (the “Company”) established the
Company’s 2019 Equity Incentive Plan by an original instrument adopted by the Company on November 25, 2019 (the “Plan”), as amended on March 12, 2020; 

B. The Plan currently provides for 7,062,006 shares of Common Stock to be reserved for issuance under the Plan; and 

C. The Company now wishes to amend the Plan to increase the number of shares of Common Stock reserved under the plan to
7,312,006 shares. 
 The Plan is amended as follows: 
  

	 	1.	 Section 3(a)(i) the Plan is hereby amended and restated in its entirety as follows: 

“Subject to Section 9(a) relating to Capitalization Adjustments, the aggregate number of shares of Common Stock that may be issued
pursuant to Stock Awards from and after the Effective Date will not exceed 7,312,006 shares (the “Share Reserve”).” 
  

	 	2.	 In all other respects, the Plan remains the same. 

[SIGNATURE PAGE FOLLOWS] 

 The Company has caused this Second Amendment to the Company’s 2019 Equity Incentive
Plan to be executed this 6th day of October, 2020. 
  

			
	AFFINIA THERAPEUTICS INC.
		
	By:	 	 /s/Rick Modi

		 	Rick Modi
		 	Chief Executive Officer

 THIRD AMENDMENT TO THE

 AFFINIA THERAPEUTICS INC. 

2019 EQUITY INCENTIVE PLAN 

A. Affinia Therapeutics Inc., a Delaware corporation (the “Company”) established the Company’s 2019 Equity
Incentive Plan by an original instrument adopted by the Company on November 25, 2019 (the “Plan”), as amended on March 12, 2020 and October 6, 2020; 

B. The Plan currently provides for 7,312,006 shares of Common Stock to be reserved for issuance under the Plan; and 

C. The Company now wishes to amend the Plan to increase the number of shares of Common Stock reserved under the plan to 11,312,006
shares. 
 The Plan is amended as follows: 
  

	1.	 Section 3(a)(i) the Plan is hereby amended and restated in its entirety as follows: 

“Subject to Section 9(a) relating to Capitalization Adjustments, the aggregate number of shares of Common Stock that may be issued
pursuant to Stock Awards from and after the Effective Date will not exceed 11,312,006 shares (the “Share Reserve”).” 

 

	2.	 In all other respects, the Plan remains the same. 

[SIGNATURE PAGE FOLLOWS] 

 The Company has caused this Third Amendment to the Company’s 2019 Equity Incentive Plan
to be executed this 20th day of April, 2021. 
  

			
	AFFINIA THERAPEUTICS INC. 
		
	By:	 	 /s/ Rick Modi

		 	Rick Modi
		 	Chief Executive Officer

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