Document:

EX-10.1

 Exhibit 10.1 

CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 
 SECTION
1. GENERAL PURPOSE OF THE PLAN; DEFINITIONS 
 The name of the plan is the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the
“Plan”). The purpose of the Plan is to encourage and enable the officers, employees, directors, Consultants and other key persons of Cabaletta Bio, Inc., a Delaware corporation (including any successor entity, the “Company”), and
its Subsidiaries, upon whose judgment, initiative and efforts the Company largely depends for the successful conduct of its business, to acquire a proprietary interest in the Company. 

The following terms shall be defined as set forth below: 

“Affiliate” of any Person means a Person that directly or indirectly, through one or more intermediaries, controls, is
controlled by or is under common control with the first mentioned Person. A Person shall be deemed to control another Person if such first Person possesses directly or indirectly the power to direct, or cause the direction of, the management and
policies of the second Person, whether through the ownership of voting securities, by contract or otherwise. 
 “Award” or
“Awards,” except where referring to a particular category of grant under the Plan, shall include Incentive Stock Options, Non-Qualified Stock Options, Restricted Stock Awards, Unrestricted
Stock Awards, Restricted Stock Units or any combination of the foregoing. 
 “Award Agreement” means a written or
electronic agreement setting forth the terms and provisions applicable to an Award granted under the Plan. Each Award Agreement may contain terms and conditions in addition to those set forth in the Plan; provided, however, in the event of
any conflict in the terms of the Plan and the Award Agreement, the terms of the Plan shall govern. 
 “Board” means
the Board of Directors of the Company. 
 “Cause” shall have the meaning as set forth in the Award Agreement(s). In the
case that any Award Agreement does not contain a definition of “Cause,” it shall mean (i) the grantee’s dishonest statements or acts with respect to the Company or any Affiliate of the Company, or any current or prospective
customers, suppliers vendors or other third parties with which such entity does business; (ii) the grantee’s commission of (A) a felony or (B) any misdemeanor involving moral turpitude, deceit, dishonesty or fraud; (iii) the
grantee’s failure to perform his assigned duties and responsibilities to the reasonable satisfaction of the Company which failure continues, in the reasonable judgment of the Company, after written notice given to the grantee by the Company;
(iv) the grantee’s gross negligence, willful misconduct or insubordination with respect to the Company or any Affiliate of the Company; or (v) the grantee’s material violation of any provision of any agreement(s) between the
grantee and the Company relating to noncompetition, nonsolicitation, nondisclosure and/or assignment of inventions. 

  

 “Chief Executive Officer” means the Chief Executive Officer of the Company
or, if there is no Chief Executive Officer, then the President of the Company. 
 “Code” means the Internal Revenue Code of
1986, as amended, and any successor Code, and related rules, regulations and interpretations. 
 “Committee” means the
Committee of the Board referred to in Section 2. 
 “Consultant” means any natural person that provides bona fide
services to the Company (including a Subsidiary), and such services are not in connection with the offer or sale of securities in a capital-raising transaction and do not directly or indirectly promote or maintain a market for the Company’s
securities. 
 “Disability” means “disability” as defined in Section 422(c) of the Code. 

“Effective Date” means the date on which the Plan is adopted as set forth on the final page of the Plan. 

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

“Fair Market Value” of the Stock on any given date means the fair market value of the Stock determined in good faith by the
Committee based on the reasonable application of a reasonable valuation method not inconsistent with Section 409A of the Code. If the Stock is admitted to trade on a national securities exchange, the determination shall be made by reference to
the closing price reported on such exchange. If there is no closing price for such date, the determination shall be made by reference to the last date preceding such date for which there is a closing price. If the date for which Fair Market Value is
determined is the first day when trading prices for the Stock are reported on a national securities exchange, the Fair Market Value shall be the “Price to the Public” (or equivalent) set forth on the cover page for the final prospectus
relating to the Company’s Initial Public Offering. 
 “Good Reason” shall have the meaning as set forth in the Award
Agreement(s). In the case that any Award Agreement does not contain a definition of “Good Reason,” it shall mean (i) a material diminution in the grantee’s base salary except for across-the-board salary reductions similarly affecting all or substantially all similarly situated employees of the Company or (ii) a change of more than 50 miles in the geographic location at which the
grantee provides services to the Company, so long as the grantee provides at least 90 days’ notice to the Company following the initial occurrence of any such event and the Company fails to cure such event within 30 days thereafter. 

“Grant Date” means the date that the Committee designates in its approval of an Award in accordance with applicable law as
the date on which the Award is granted, which date may not precede the date of such Committee approval. 
 “Holder” means,
with respect to an Award or any Shares, the Person holding such Award or Shares, including the initial recipient of the Award or any Permitted Transferee. 

  
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 “Incentive Stock Option” means any Stock Option designated and qualified as
an “incentive stock option” as defined in Section 422 of the Code. 
 “Initial Public Offering” means the
consummation of the first firm commitment underwritten public offering pursuant to an effective registration statement under the Securities Act covering the offer and sale by the Company of its equity securities, as a result of or following which
the Stock shall be publicly held. 
 “Non-Qualified Stock Option” means any Stock
Option that is not an Incentive Stock Option. 
 “Option” or “Stock Option” means any option to purchase
shares of Stock granted pursuant to Section 5. 
 “Permitted Transferees” shall mean any of the following to whom a
Holder may transfer Shares hereunder (as set forth in Section 9(a)(ii)(A)): the Holder’s child, stepchild, grandchild, parent, stepparent, grandparent, spouse, former spouse, sibling, niece, nephew, mother-in-law, father-in-law, son-in-law, daughter-in-law, brother-in-law, or sister-in-law, including adoptive relationships, any person sharing the Holder’s household (other than a tenant or employee), a trust in which these persons have more than fifty percent of the beneficial
interest, a foundation in which these persons control the management of assets, and any other entity in which these persons own more than fifty percent of the voting interests; provided, however, that any such trust does not require or permit
distribution of any Shares during the term of the Award Agreement unless subject to its terms. Upon the death of the Holder, the term Permitted Transferees shall also include such deceased Holder’s estate, executors, administrators, personal
representatives, heirs, legatees and distributees, as the case may be. 
 “Person” shall mean any individual, corporation,
partnership (limited or general), limited liability company, limited liability partnership, association, trust, joint venture, unincorporated organization or any similar entity. 

“Restricted Stock Award” means Awards granted pursuant to Section 6 and “Restricted Stock” means Shares
issued pursuant to such Awards. 
 “Restricted Stock Unit” means an Award of phantom stock units to a grantee, which may be
settled in cash or Shares as determined by the Committee, pursuant to Section 8. 
 “Sale Event” means the
consummation of (i) the dissolution or liquidation of the Company, (ii) the sale of all or substantially all of the assets of the Company on a consolidated basis to an unrelated person or entity, (iii) a merger, reorganization or
consolidation pursuant to which the holders of the Company’s outstanding voting power immediately prior to such transaction do not own a majority of the outstanding voting power of the surviving or resulting entity (or its ultimate parent, if
applicable), (iv) the acquisition of all or a majority of the outstanding voting stock of the Company in a single transaction or a series of related transactions by a Person or group of Persons, or (v) any other acquisition of the business of
the Company, as determined by the Board; provided, however, that the Company’s Initial Public Offering, any subsequent public offering or another capital raising event, or a merger effected solely to change the Company’s domicile
shall not constitute a “Sale Event.” 

  
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 “Section 409A” means Section 409A of the Code and
the regulations and other guidance promulgated thereunder. 
 “Securities Act” means the Securities Act of 1933, as
amended, and the rules and regulations thereunder. 
 “Service Relationship” means any relationship as a full-time
employee, part-time employee, director or other key person (including Consultants) of the Company or any Subsidiary or any successor entity (e.g., a Service Relationship shall be deemed to continue without interruption in the event an
individual’s status changes from full-time employee to part- time employee or Consultant). 
 “Shares” means shares of
Stock. 
 “Stock” means the Common Stock, par value $0.00001 per share, of the Company. 

“Subsidiary” means any corporation or other entity (other than the Company) in which the Company has more than a
50 percent interest, either directly or indirectly. 
 “Ten Percent Owner” means an employee who owns or is deemed to
own (by reason of the attribution rules of Section 424(d) of the Code) more than 10 percent of the combined voting power of all classes of stock of the Company or any parent of the Company or any Subsidiary. 

“Termination Event” means the termination of the Award recipient’s Service Relationship with the Company and its
Subsidiaries for any reason whatsoever, regardless of the circumstances thereof, and including, without limitation, upon death, disability, retirement, discharge or resignation for any reason, whether voluntarily or involuntarily. The following
shall not constitute a Termination Event: (i) a transfer to the service of the Company from a Subsidiary or from the Company to a Subsidiary, or from one Subsidiary to another Subsidiary or (ii) an approved leave of absence for military
service or sickness, or for any other purpose approved by the Committee, if the individual’s right to re-employment is guaranteed either by a statute or by contract or under the policy pursuant to which
the leave of absence was granted or if the Committee otherwise so provides in writing. 
 “Unrestricted Stock Award” means
any Award granted pursuant to Section 7 and 
 “Unrestricted Stock” means Shares issued pursuant to such Awards. 

SECTION 2. ADMINISTRATION OF PLAN; COMMITTEE AUTHORITY TO SELECT GRANTEES AND DETERMINE AWARDS 

(a) Administration of Plan. The Plan shall be administered by the Board, or at the discretion of the Board, by a committee of the Board,
comprised of not less than two directors. All references herein to the “Committee” shall be deemed to refer to the group then responsible for administration of the Plan at the relevant time (i.e., either the Board of Directors or a
committee or committees of the Board, as applicable). 
 (b) Powers of Committee. The Committee shall have the power and authority to
grant Awards consistent with the terms of the Plan, including the power and authority: 

  
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 (i) to select the individuals to whom Awards may from time to time be granted; 

(ii) to determine the time or times of grant, and the amount, if any, of Incentive Stock Options,
Non-Qualified Stock Options, Restricted Stock Awards, Unrestricted Stock Awards, Restricted Stock Units, or any combination of the foregoing, granted to any one or more grantees; 

(iii) to determine the number of Shares to be covered by any Award and, subject to the provisions of the Plan, the price, exercise price,
conversion ratio or other price relating thereto; 
 (iv) to determine and, subject to Section 12, to modify from time to time the terms
and conditions, including restrictions, not inconsistent with the terms of the Plan, of any Award, which terms and conditions may differ among individual Awards and grantees, and to approve the form of Award Agreements; 

(v) to accelerate at any time the exercisability or vesting of all or any portion of any Award; 

(vi) to impose any limitations on Awards, including limitations on transfers, repurchase provisions and the like, and to exercise repurchase
rights or obligations; 
 (vii) subject to Section 5(a)(ii) and any restrictions imposed by Section 409A, to extend at any time the
period in which Stock Options may be exercised; and 
 (viii) at any time to adopt, alter and repeal such rules, guidelines and practices for
administration of the Plan and for its own acts and proceedings as it shall deem advisable; to interpret the terms and provisions of the Plan and any Award (including Award Agreements); to make all determinations it deems advisable for the
administration of the Plan; to decide all disputes arising in connection with the Plan; and to otherwise supervise the administration of the Plan. 
 All
decisions and interpretations of the Committee shall be binding on all persons, including the Company and all Holders. 
 (c) Award
Agreement. Awards under the Plan shall be evidenced by Award Agreements that set forth the terms, conditions and limitations for each Award. 

(d) Indemnification. Neither the Board nor the Committee, nor any member of either or any delegate thereof, shall be liable for any act,
omission, interpretation, construction or determination made in good faith in connection with the Plan, and the members of the Board and the Committee (and any delegate thereof) shall be entitled in all cases to indemnification and reimbursement by
the Company in respect of any claim, loss, damage or expense (including, without limitation, reasonable attorneys’ fees) arising or resulting therefrom to the fullest extent permitted by law and/or under the Company’s governing documents,
including its certificate of incorporation or bylaws, or any directors’ and officers’ liability insurance coverage which may be in effect from time to time and/or any indemnification agreement between such individual and the Company. 

  
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 (e) Foreign Award Recipients. Notwithstanding any provision of the Plan to the
contrary, in order to comply with the laws in other countries in which the Company and any Subsidiary operate or have employees or other individuals eligible for Awards, the Committee, in its sole discretion, shall have the power and authority to:
(i) determine which Subsidiaries, if any, shall be covered by the Plan; (ii) determine which individuals, if any, outside the United States are eligible to participate in the Plan; (iii) modify the terms and conditions of any Award
granted to individuals outside the United States to comply with applicable foreign laws; (iv) establish subplans and modify exercise procedures and other terms and procedures, to the extent the Committee determines such actions to be necessary
or advisable (and such subplans and/or modifications shall be attached to the Plan as appendices); provided, however, that no such subplans and/or modifications shall increase the share limitation contained in Section 3(a) hereof;
and (v) take any action, before or after an Award is made, that the Committee determines to be necessary or advisable to obtain approval or comply with any local governmental regulatory exemptions or approvals. 

SECTION 3. STOCK ISSUABLE UNDER THE PLAN; MERGERS AND OTHER TRANSACTIONS; SUBSTITUTION 

(a) Stock Issuable. The maximum number of Shares reserved and available for issuance under the Plan shall be 1,275,000 Shares, subject
to adjustment as provided in Section 3(b). For purposes of this limitation, the Shares underlying any Awards that are forfeited, canceled, reacquired by the Company prior to vesting, satisfied without the issuance of Stock or otherwise
terminated (other than by exercise) and Shares that are withheld upon exercise of an Option or settlement of an Award to cover the exercise price or tax withholding shall be added back to the Shares available for issuance under the Plan. Subject to
such overall limitations, Shares may be issued up to such maximum number pursuant to any type or types of Award, and no more than 1,530,000 Shares may be issued pursuant to Incentive Stock Options. The Shares available for issuance under the Plan
may be authorized but unissued Shares or Shares reacquired by the Company. 
 (b) Changes in Stock. Subject to Section 3(c)
hereof, if, as a result of any reorganization, recapitalization, reclassification, stock dividend, stock split, reverse stock split or other similar change in the Company’s capital stock, the outstanding Shares are increased or decreased or are
exchanged for a different number or kind of shares or other securities of the Company, or additional Shares or new or different shares or other securities of the Company or other non-cash assets are
distributed with respect to such Shares or other securities, in each case, without the receipt of consideration by the Company, or, if, as a result of any merger or consolidation, or sale of all or substantially all of the assets of the Company, the
outstanding Shares are converted into or exchanged for other securities of the Company or any successor entity (or a parent or subsidiary thereof), the Committee shall make an appropriate and proportionate adjustment in (i) the maximum number
of Shares reserved for issuance under the Plan, (ii) the number and kind of Shares or other securities subject to any then outstanding Awards under the Plan, (iii) the repurchase price, if any, per Share subject to each outstanding Award,
and (iv) the exercise price for each Share subject to any then outstanding Stock Options 

  
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 under the Plan, without changing the aggregate exercise price (i.e., the exercise price multiplied by the
number of Stock Options) as to which such Stock Options remain exercisable. The Committee shall in any event make such adjustments as may be required by Section 25102(o) of the California Corporation Code and the rules and regulations
promulgated thereunder. The adjustment by the Committee shall be final, binding and conclusive. No fractional Shares shall be issued under the Plan resulting from any such adjustment, but the Committee in its discretion may make a cash payment in
lieu of fractional shares. 
 (c) Sale Events. 

(i) Options. 

(A) In the case of and subject to the consummation of a Sale Event, the Plan and all outstanding Options issued hereunder shall
terminate upon the effective time of any such Sale Event unless assumed or continued by the successor entity, or new stock options or other awards of the successor entity or parent thereof are substituted therefor, with an equitable or proportionate
adjustment as to the number and kind of shares and, if appropriate, the per share exercise prices, as such parties shall agree (after taking into account any acceleration hereunder and/or pursuant to the terms of any Award Agreement). 

(B) In the event of the termination of the Plan and all outstanding Options issued hereunder pursuant to Section 3(c),
each Holder of Options shall be permitted, within a period of time prior to the consummation of the Sale Event as specified by the Committee, to exercise all such Options which are then exercisable or will become exercisable as of the effective time
of the Sale Event; provided, however, that the exercise of Options not exercisable prior to the Sale Event shall be subject to the consummation of the Sale Event. 

(C) Notwithstanding anything to the contrary in Section 3(c)(i)(A), in the event of a Sale Event, the Company shall have
the right, but not the obligation, to make or provide for a cash payment to the Holders of Options, without any consent of the Holders, in exchange for the cancellation thereof, in an amount equal to the difference between (A) the value as
determined by the Committee of the consideration payable per share of Stock pursuant to the Sale Event (the “Sale Price”) times the number of Shares subject to outstanding Options being cancelled (to the extent then vested and exercisable,
including by reason of acceleration in connection with such Sale Event, at prices not in excess of the Sale Price) and (B) the aggregate exercise price of all such outstanding vested and exercisable Options. 

(ii) Restricted Stock and Restricted Stock Unit Awards. 

(A) In the case of and subject to the consummation of a Sale Event, all unvested Restricted Stock and unvested Restricted Stock
Unit Awards (other than those becoming vested as a result of the Sale Event) issued hereunder shall be forfeited immediately prior to the effective time of any such Sale Event unless assumed or continued by the successor entity, or awards of the
successor entity or parent thereof are substituted therefor, with an equitable or proportionate adjustment as to the number and kind of shares subject to such awards as such parties shall agree (after taking into account any acceleration hereunder
and/or pursuant to the terms of any Award Agreement). 

  
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 (B) In the event of the forfeiture of Restricted Stock pursuant to
Section 3(c)(ii)(A), such Restricted Stock shall be repurchased from the Holder thereof at a price per share equal to the original per share purchase price paid by the Holder (subject to adjustment as provided in Section 3(b)) for such
Shares. 
 (C) Notwithstanding anything to the contrary in Section 3(c)(ii)(A), in the event of a Sale Event, the
Company shall have the right, but not the obligation, to make or provide for a cash payment to the Holders of Restricted Stock or Restricted Stock Unit Awards, without consent of the Holders, in exchange for the cancellation thereof, in an amount
equal to the Sale Price times the number of Shares subject to such Awards, to be paid at the time of such Sale Event or upon the later vesting of such Awards. 

SECTION 4. ELIGIBILITY 
 Grantees under
the Plan will be such full or part-time officers and other employees, directors, Consultants and key persons of the Company and any Subsidiary who are selected from time to time by the Committee in its sole discretion; provided,
however, that Awards shall be granted only to those individuals described in Rule 701(c) of the Securities Act. 
 SECTION 5. STOCK
OPTIONS 
 Upon the grant of a Stock Option, the Company and the grantee shall enter into an Award Agreement. The terms and conditions of
each such Award Agreement shall be determined by the Committee, and such terms and conditions may differ among individual Awards and grantees. 

Stock Options granted under the Plan may be either Incentive Stock Options or Non- Qualified Stock Options. Incentive Stock Options may be
granted only to employees of the Company or any Subsidiary that is a “subsidiary corporation” within the meaning of Section 424(f) of the Code. To the extent that any Option does not qualify as an Incentive Stock Option, it shall be
deemed a Non-Qualified Stock Option. 
 (a) Terms of Stock Options. The Committee in its
discretion may grant Stock Options to those individuals who meet the eligibility requirements of Section 4. Stock Options shall be subject to the following terms and conditions and shall contain such additional terms and conditions, not
inconsistent with the terms of the Plan, as the Committee shall deem desirable. 
 (i) Exercise Price. The exercise price per share
for the Shares covered by a Stock Option shall be determined by the Committee at the time of grant but shall not be less than 100 percent of the Fair Market Value on the Grant Date. In the case of an Incentive Stock Option that is granted to a
Ten Percent Owner, the exercise price per share for the Shares covered by such Incentive Stock Option shall not be less than 110 percent of the Fair Market Value on the Grant Date. 

  
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 (ii) Option Term. The term of each Stock Option shall be fixed by the Committee, but
no Stock Option shall be exercisable more than ten years from the Grant Date. In the case of an Incentive Stock Option that is granted to a Ten Percent Owner, the term of such Stock Option shall be no more than five years from the Grant Date. 

(iii) Exercisability; Rights of a Stockholder. Stock Options shall become exercisable and/or vested at such time or times, whether or
not in installments, as shall be determined by the Committee at or after the Grant Date. The Award Agreement may permit a grantee to exercise all or a portion of a Stock Option immediately at grant; provided that the Shares issued upon such exercise
shall be subject to restrictions and a vesting schedule identical to the vesting schedule of the related Stock Option, such Shares shall be deemed to be Restricted Stock for purposes of the Plan, and the optionee may be required to enter into an
additional or new Award Agreement as a condition to exercise of such Stock Option. An optionee shall have the rights of a stockholder only as to Shares acquired upon the exercise of a Stock Option and not as to unexercised Stock Options. An optionee
shall not be deemed to have acquired any Shares unless and until a Stock Option shall have been exercised pursuant to the terms of the Award Agreement and this Plan and the optionee’s name has been entered on the books of the Company as a
stockholder. 
 (iv) Method of Exercise. Stock Options may be exercised by an optionee in whole or in part, by the optionee giving
written or electronic notice of exercise to the Company, specifying the number of Shares to be purchased. Payment of the purchase price may be made by one or more of the following methods (or any combination thereof) to the extent provided in the
Award Agreement: 
 (A) In cash, by certified or bank check, by wire transfer of immediately available funds, or other
instrument acceptable to the Committee; 
 (B) If permitted by the Committee, by the optionee delivering to the Company a
promissory note, if the Board has expressly authorized the loan of funds to the optionee for the purpose of enabling or assisting the optionee to effect the exercise of his or her Stock Option; provided, that at least so much of the exercise
price as represents the par value of the Stock shall be paid in cash if required by state law; 
 (C) If permitted by the
Committee and the Initial Public Offering has occurred (or the Stock otherwise becomes publicly-traded), through the delivery (or attestation to the ownership) of Shares that have been purchased by the optionee on the open market or that are
beneficially owned by the optionee and are not then subject to restrictions under any Company plan. To the extent required to avoid variable accounting treatment under ASC 718 or other applicable accounting rules, such surrendered Shares if
originally purchased from the Company shall have been owned by the optionee for at least six months. Such surrendered Shares shall be valued at Fair Market Value on the exercise date; 

  
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 (D) If permitted by the Committee and the Initial Public Offering has
occurred (or the Stock otherwise becomes publicly-traded), by the optionee delivering to the Company a properly executed exercise notice together with irrevocable instructions to a broker to promptly deliver to the Company cash or a check payable
and acceptable to the Company for the purchase price; provided that in the event the optionee chooses to pay the purchase price as so provided, the optionee and the broker shall comply with such procedures and enter into such agreements of
indemnity and other agreements as the Committee shall prescribe as a condition of such payment procedure; or 
 (E) If
permitted by the Committee, and only with respect to Stock Options that are not Incentive Stock Options, by a “net exercise” arrangement pursuant to which the Company will reduce the number of Shares issuable upon exercise by the largest
whole number of Shares with a Fair Market Value that does not exceed the aggregate exercise price. 
 Payment instruments will be received
subject to collection. No certificates for Shares so purchased will be issued to the optionee or, with respect to uncertificated Stock, no transfer to the optionee on the records of the Company will take place, until the Company has completed all
steps it has deemed necessary to satisfy legal requirements relating to the issuance and sale of the Shares, which steps may include, without limitation, (i) receipt of a representation from the optionee at the time of exercise of the Option
that the optionee is purchasing the Shares for the optionee’s own account and not with a view to any sale or distribution of the Shares or other representations relating to compliance with applicable law governing the issuance of securities,
(ii) the legending of the certificate (or notation on any book entry) representing the Shares to evidence the foregoing restrictions, and (iii) obtaining from optionee payment or provision for all withholding taxes due as a result of the
exercise of the Option. The delivery of certificates representing the shares of Stock (or the transfer to the optionee on the records of the Company with respect to uncertificated Stock) to be purchased pursuant to the exercise of a Stock Option
will be contingent upon (A) receipt from the optionee (or a purchaser acting in his or her stead in accordance with the provisions of the Stock Option) by the Company of the full purchase price for such Shares and the fulfillment of any other
requirements contained in the Award Agreement or applicable provisions of laws and (B) if required by the Company, the optionee shall have entered into any stockholders agreements or other agreements with the Company and/or certain other of the
Company’s stockholders relating to the Stock. In the event an optionee chooses to pay the purchase price by previously-owned Shares through the attestation method, the number of Shares transferred to the optionee upon the exercise of the Stock
Option shall be net of the number of Shares attested to. 
 (b) Annual Limit on Incentive Stock Options. To the extent required for
“incentive stock option” treatment under Section 422 of the Code, the aggregate Fair Market Value (determined as of the Grant Date) of the Shares with respect to which Incentive Stock Options granted under the Plan and any other plan
of the Company or its parent and any Subsidiary that become exercisable for the first time by an optionee during any calendar year shall not exceed $100,000 or such other limit as may be in effect from time to time under Section 422 of the
Code. To the extent that any Stock Option exceeds this limit, it shall constitute a Non-Qualified Stock Option. 

  
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 (c) Termination. Any portion of a Stock Option that is not vested and exercisable on
the date of termination of an optionee’s Service Relationship shall immediately expire and be null and void. Once any portion of the Stock Option becomes vested and exercisable, the optionee’s right to exercise such portion of the Stock
Option (or the optionee’s representatives and legatees as applicable) in the event of a termination of the optionee’s Service Relationship shall continue until the earliest of: (i) the date which is: (A) 12 months following the date
on which the optionee’s Service Relationship terminates due to death or Disability (or such longer period of time as determined by the Committee and set forth in the applicable Award Agreement), or (B) three months following the date on
which the optionee’s Service Relationship terminates if the termination is due to any reason other than death or Disability (or such longer period of time as determined by the Committee and set forth in the applicable Award Agreement), or
(ii) the Expiration Date set forth in the Award Agreement; provided that notwithstanding the foregoing, an Award Agreement may provide that if the optionee’s Service Relationship is terminated for Cause, the Stock Option shall
terminate immediately and be null and void upon the date of the optionee’s termination and shall not thereafter be exercisable. 
 SECTION 6.
RESTRICTED STOCK AWARDS 
 (a) Nature of Restricted Stock Awards. The Committee may, in its sole discretion, grant (or sell at
par value or such other purchase price determined by the Committee) to an eligible individual under Section 4 hereof a Restricted Stock Award under the Plan. The Committee shall determine the restrictions and conditions applicable to each
Restricted Stock Award at the time of grant. Conditions may be based on continuing employment (or other Service Relationship), achievement of pre-established performance goals and objectives and/or such other
criteria as the Committee may determine. Upon the grant of a Restricted Stock Award, the Company and the grantee shall enter into an Award Agreement. The terms and conditions of each such Award Agreement shall be determined by the Committee, and
such terms and conditions may differ among individual Awards and grantees. 
 (b) Rights as a Stockholder. Upon the grant of the
Restricted Stock Award and payment of any applicable purchase price, a grantee of Restricted Stock shall be considered the record owner of and shall be entitled to vote the Restricted Stock if, and to the extent, such Shares are entitled to voting
rights, subject to such conditions contained in the Award Agreement. The grantee shall be entitled to receive all dividends and any other distributions declared on the Shares; provided, however, that the Company is under
no duty to declare any such dividends or to make any such distribution. Unless the Committee shall otherwise determine, certificates evidencing the Restricted Stock shall remain in the possession of the Company until such Restricted Stock is vested
as provided in subsection (d) below of this Section, and the grantee shall be required, as a condition of the grant, to deliver to the Company a stock power endorsed in blank and such other instruments of transfer as the Committee may
prescribe. 
 (c) Restrictions. Restricted Stock may not be sold, assigned, transferred, pledged or otherwise encumbered or disposed
of except as specifically provided herein or in the Award Agreement. Except as may otherwise be provided by the Committee either in the Award Agreement or, subject to Section 12 below, in writing after the Award Agreement is issued, if a
grantee’s Service Relationship with the Company and any Subsidiary terminates, the Company or its assigns shall have the right, as may be specified in the relevant instrument, to repurchase some or all of the Shares subject to the Award at such
purchase price as is set forth in the Award Agreement. 

  
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 (d) Vesting of Restricted Stock. The Committee at the time of grant shall specify in
the Award Agreement the date or dates and/or the attainment of pre-established performance goals, objectives and other conditions on which the substantial risk of forfeiture imposed shall lapse and the
Restricted Stock shall become vested, subject to such further rights of the Company or its assigns as may be specified in the Award Agreement. 
 SECTION 7.
UNRESTRICTED STOCK AWARDS 
 The Committee may, in its sole discretion, grant (or sell at par value or such other purchase price
determined by the Committee) to an eligible person under Section 4 hereof an Unrestricted Stock Award under the Plan. Unrestricted Stock Awards may be granted in respect of past services or other valid consideration, or in lieu of cash
compensation due to such grantee. 
 SECTION 8. RESTRICTED STOCK UNITS 

(a) Nature of Restricted Stock Units. The Committee may, in its sole discretion, grant to an eligible person under Section 4 hereof
Restricted Stock Units under the Plan. The Committee shall determine the restrictions and conditions applicable to each Restricted Stock Unit at the time of grant. Vesting conditions may be based on continuing employment (or other Service
Relationship), achievement of pre-established performance goals and objectives and/or other such criteria as the Committee may determine. Upon the grant of Restricted Stock Units, the grantee and the Company
shall enter into an Award Agreement. The terms and conditions of each such Award Agreement shall be determined by the Committee and may differ among individual Awards and grantees. On or promptly following the vesting date or dates applicable to any
Restricted Stock Unit, but in no event later than March 15 of the year following the year in which such vesting occurs, such Restricted Stock Unit(s) shall be settled in the form of cash or shares of Stock, as specified in the Award Agreement.
Restricted Stock Units may not be sold, assigned, transferred, pledged, or otherwise encumbered or disposed of. 
 (b) Rights as a
Stockholder. A grantee shall have the rights of a stockholder only as to Shares, if any, acquired upon settlement of Restricted Stock Units. A grantee shall not be deemed to have acquired any such Shares unless and until the Restricted Stock
Units shall have been settled in Shares pursuant to the terms of the Plan and the Award Agreement, the Company shall have issued and delivered a certificate representing the Shares to the grantee (or transferred on the records of the Company with
respect to uncertificated stock), and the grantee’s name has been entered in the books of the Company as a stockholder. 
 (c)
Termination. Except as may otherwise be provided by the Committee either in the Award Agreement or in writing after the Award Agreement is issued, a grantee’s right in all Restricted Stock Units that have not vested shall automatically
terminate upon the grantee’s cessation of Service Relationship with the Company and any Subsidiary for any reason. 

  
 12 

 SECTION 9. TRANSFER RESTRICTIONS; COMPANY RIGHT OF FIRST REFUSAL; COMPANY REPURCHASE RIGHTS

 (a) Restrictions on Transfer. 

(i) Non-Transferability of Stock Options. Stock Options and, prior to exercise, the Shares
issuable upon exercise of such Stock Option, shall not be transferable by the optionee otherwise than by will, or by the laws of descent and distribution, and all Stock Options shall be exercisable, during the optionee’s lifetime, only by the
optionee, or by the optionee’s legal representative or guardian in the event of the optionee’s incapacity. Notwithstanding the foregoing, the Committee, in its sole discretion, may provide in the Award Agreement regarding a given Stock
Option that the optionee may transfer by gift, without consideration for the transfer, his or her Non-Qualified Stock Options to his or her family members (as defined in Rule 701 of the Securities Act), to
trusts for the benefit of such family members, or to partnerships in which such family members are the only partners (to the extent such trusts or partnerships are considered “family members” for purposes of Rule 701 of the Securities
Act), provided that the transferee agrees in writing with the Company to be bound by all of the terms and conditions of this Plan and the applicable Award Agreement, including the execution of a stock power upon the issuance of Shares. Stock
Options, and the Shares issuable upon exercise of such Stock Options, shall be restricted as to any pledge, hypothecation, or other transfer, including any short position, any “put equivalent position” (as defined in the Exchange Act) or
any “call equivalent position” (as defined in the Exchange Act) prior to exercise. 
 (ii) Shares. No Shares shall be sold,
assigned, transferred, pledged, hypothecated, given away or in any other manner disposed of or encumbered, whether voluntarily or by operation of law, unless (i) the transfer is in compliance with the terms of the applicable Award Agreement,
all applicable securities laws (including, without limitation, the Securities Act), and with the terms and conditions of this Section 9, (ii) the transfer does not cause the Company to become subject to the reporting requirements of the
Exchange Act, and (iii) the transferee consents in writing to be bound by the provisions of the Plan and the Award Agreement, including this Section 9. In connection with any proposed transfer, the Committee may require the transferor to
provide at the transferor’s own expense an opinion of counsel to the transferor, satisfactory to the Committee, that such transfer is in compliance with all foreign, federal and state securities laws (including, without limitation, the
Securities Act). Any attempted transfer of Shares not in accordance with the terms and conditions of this Section 9 shall be null and void, and the Company shall not reflect on its records any change in record ownership of any Shares as a
result of any such transfer, shall otherwise refuse to recognize any such transfer and shall not in any way give effect to any such transfer of Shares. The Company shall be entitled to seek protective orders, injunctive relief and other remedies
available at law or in equity including, without limitation, seeking specific performance or the rescission of any transfer not made in strict compliance with the provisions of this Section 9. Subject to the foregoing general provisions, and
unless otherwise provided in the applicable Award Agreement, Shares may be transferred pursuant to the following specific terms and conditions (provided that with respect to any transfer of Restricted Stock, all vesting and forfeiture provisions
shall continue to apply with respect to the original recipient): 

  
 13 

 (A) Transfers to Permitted Transferees. The Holder may transfer any
or all of the Shares to one or more Permitted Transferees; provided, however, that following such transfer, such Shares shall continue to be subject to the terms of this Plan (including this Section 9) and such Permitted Transferee(s)
shall, as a condition to any such transfer, deliver a written acknowledgment to that effect to the Company and shall deliver a stock power to the Company with respect to the Shares. Notwithstanding the foregoing, the Holder may not transfer any of
the Shares to a Person whom the Company reasonably determines is a direct competitor or a potential competitor of the Company or any of its Subsidiaries. 

(B) Transfers Upon Death. Upon the death of the Holder, any Shares then held by the Holder at the time of such death and
any Shares acquired after the Holder’s death by the Holder’s legal representative shall be subject to the provisions of this Plan, and the Holder’s estate, executors, administrators, personal representatives, heirs, legatees and
distributees shall be obligated to convey such Shares to the Company or its assigns under the terms contemplated by the Plan and the Award Agreement. 

(b) Right of First Refusal. In the event that a Holder desires at any time to sell or otherwise transfer all or any part of his or her
Shares (other than shares of Restricted Stock which by their terms are not transferrable), the Holder first shall give written notice to the Company of the Holder’s intention to make such transfer. Such notice shall state the number of Shares
that the Holder proposes to sell (the “Offered Shares”), the price and the terms at which the proposed sale is to be made and the name and address of the proposed transferee. At any time within 30 days after the receipt of such notice by
the Company, the Company or its assigns may elect to purchase all or any portion of the Offered Shares at the price and on the terms offered by the proposed transferee and specified in the notice. The Company or its assigns shall exercise this right
by mailing or delivering written notice to the Holder within the foregoing 30- day period. If the Company or its assigns elect to exercise its purchase rights under this Section 9(b), the closing for such purchase shall, in any event, take
place within 45 days after the receipt by the Company of the initial notice from the Holder. In the event that the Company or its assigns do not elect to exercise such purchase right, or in the event that the Company or its assigns do not pay the
full purchase price within such 45-day period, the Holder shall be required to pay a transaction processing fee of $10,000 to the Company (unless waived by the Committee) and then may, within 60 days
thereafter, sell the Offered Shares to the proposed transferee and at the same price and on the same terms as specified in the Holder’s notice. Any Shares not sold to the proposed transferee shall remain subject to the Plan. If the Holder is a
party to any stockholders agreements or other agreements with the Company and/or certain other of the Company’s stockholders relating to the Shares, (i) the transferring Holder shall comply with the requirements of such stockholders
agreements or other agreements relating to any proposed transfer of the Offered Shares, and (ii) any proposed transferee that purchases Offered Shares shall enter into such stockholders agreements or other agreements with the Company and/or
certain of the Company’s stockholders relating to the Offered Shares on the same terms and in the same capacity as the transferring Holder. 

  
 14 

 (c) Company’s Right of Repurchase. 

(i) Right of Repurchase for Unvested Shares Issued Upon the Exercise of an Option. Upon a Termination Event, the Company or its assigns
shall have the right and option to repurchase from a Holder of Shares acquired upon exercise of a Stock Option which are still subject to a risk of forfeiture as of the Termination Event. Such repurchase rights may be exercised by the Company within
the later of (A) six months following the date of such Termination Event or (B) seven months after the acquisition of Shares upon exercise of a Stock Option. The repurchase price shall be equal to the lower of the original per share price
paid by the Holder, subject to adjustment as provided in Section 3(b) of the Plan, or the current Fair Market Value of such Shares as of the date the Company elects to exercise its repurchase rights. 

(ii) Right of Repurchase With Respect to Restricted Stock. Upon a Termination Event, the Company or its assigns shall have the right and
option to repurchase from a Holder of Shares received pursuant to a Restricted Stock Award any Shares that are still subject to a risk of forfeiture as of the Termination Event. Such repurchase right may be exercised by the Company within six months
following the date of such Termination Event. The repurchase price shall be the lower of the original per share purchase price paid by the Holder, subject to adjustment as provided in Section 3(b) of the Plan, or the current Fair Market Value
of such Shares as of the date the Company elects to exercise its repurchase rights. 
 (iii) Procedure. Any repurchase right of the
Company shall be exercised by the Company or its assigns by giving the Holder written notice on or before the last day of the repurchase period of its intention to exercise such repurchase right. Upon such notification, the Holder shall promptly
surrender to the Company, free and clear of any liens or encumbrances, any certificates representing the Shares being purchased, together with a duly executed stock power for the transfer of such Shares to the Company or the Company’s assignee
or assignees. Upon the Company’s or its assignee’s receipt of the certificates from the Holder, the Company or its assignee or assignees shall deliver to him, her or them a check for the applicable repurchase price; provided,
however, that the Company may pay the repurchase price by offsetting and canceling any indebtedness then owed by the Holder to the Company. 

(d) Escrow Arrangement. 

(i) Escrow. In order to carry out the provisions of this Section 9 of this Plan more effectively, the Company shall hold any Shares
issued pursuant to Awards granted under the Plan in escrow together with separate stock powers executed by the Holder in blank for transfer. The Company shall not dispose of the Shares except as otherwise provided in this Plan. In the event of any
repurchase by the Company (or any of its assigns), the Company is hereby authorized by the Holder, as the Holder’s attorney-in-fact, to date and complete the stock
powers necessary for the transfer of the Shares being purchased and to transfer such Shares in accordance with the terms hereof. At such time as any Shares are no longer subject to the Company’s repurchase and first refusal rights, the Company
shall, at the written request of the Holder, deliver to the Holder a certificate representing such Shares with the balance of the Shares to be held in escrow pursuant to this Section. 

  
 15 

 (ii) Remedy. Without limitation of any other provision of this Plan or other rights,
in the event that a Holder or any other Person is required to sell a Holder’s Shares pursuant to the provisions of Sections 9(b) or (c) hereof and in the further event that he or she refuses or for any reason fails to deliver to the
Company or its designated purchaser of such Shares the certificate or certificates evidencing such Shares together with a related stock power, the Company or such designated purchaser may deposit the applicable purchase price for such Shares with a
bank designated by the Company, or with the Company’s independent public accounting firm, as agent or trustee, or in escrow, for such Holder or other Person, to be held by such bank or accounting firm for the benefit of and for delivery to him,
her, them or it, and/or, in its discretion, pay such purchase price by offsetting any indebtedness then owed by such Holder as provided above. Upon any such deposit and/or offset by the Company or its designated purchaser of such amount and upon
notice to the Person who was required to sell the Shares to be sold pursuant to the provisions of Sections 9(b) or (c), such Shares shall at such time be deemed to have been sold, assigned, transferred and conveyed to such purchaser, such Holder
shall have no further rights thereto (other than the right to withdraw the payment thereof held in escrow, if applicable), and the Company shall record such transfer in its stock transfer book or in any appropriate manner. 

(e) Lockup Provision. If requested by the Company, a Holder shall not sell or otherwise transfer or dispose of any Shares (including,
without limitation, pursuant to Rule 144 under the Securities Act) held by him or her for such period following the effective date of a public offering by the Company of Shares as the Company shall specify reasonably and in good faith. If requested
by the underwriter engaged by the Company, each Holder shall execute a separate letter confirming his or her agreement to comply with this Section. 

(f) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reclassification, stock
dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding Shares are increased or decreased or are exchanged for a different number or kind of securities of the Company, the restrictions contained in
this Section 9 shall apply with equal force to additional and/or substitute securities, if any, received by Holder in exchange for, or by virtue of his or her ownership of, Shares. 

(g) Termination. The terms and provisions of Section 9(b) and Section 9(c) (except for the Company’s right to repurchase
Shares still subject to a risk of forfeiture upon a Termination Event) shall terminate upon the closing of the Company’s Initial Public Offering or upon consummation of any Sale Event, in either case as a result of which Shares are registered
under Section 12 of the Exchange Act and publicly-traded on any national security exchange. 
 SECTION 10. TAX WITHHOLDING 

(a) Payment by Grantee. Each grantee shall, no later than the date as of which the value of an Award or of any Shares or other amounts
received thereunder first becomes includable in the gross income of the grantee for income tax purposes, pay to the Company, or make arrangements satisfactory to the Committee regarding payment of, any Federal, state, or local taxes of any kind
required by law to be withheld by the Company with respect to such income. The Company and any Subsidiary shall, to the extent permitted by law, have the right to deduct any such taxes from any payment of any kind otherwise due to the grantee. The
Company’s obligation to deliver stock certificates (or evidence of book entry) to any grantee is subject to and conditioned on any such tax withholding obligations being satisfied by the grantee. 

  
 16 

 (b) Payment in Stock. The Company’s minimum required tax withholding obligation
may be satisfied, in whole or in part, by the Company withholding from Shares to be issued pursuant to an Award a number of Shares having an aggregate Fair Market Value (as of the date the withholding is effected) that would satisfy the minimum
withholding amount due. 
 SECTION 11. SECTION 409A AWARDS. 

To the extent that any Award is determined to constitute “nonqualified deferred compensation” within the meaning of Section 409A
(a “409A Award”), the Award shall be subject to such additional rules and requirements as may be specified by the Committee from time to time. In this regard, if any amount under a 409A Award is payable upon a “separation from
service” (within the meaning of Section 409A) to a grantee who is considered a “specified employee” (within the meaning of Section 409A), then no such payment shall be made prior to the date that is the earlier of
(i) six months and one day after the grantee’s separation from service, or (ii) the grantee’s death, but only to the extent such delay is necessary to prevent such payment from being subject to interest, penalties and/or
additional tax imposed pursuant to Section 409A. The Company makes no representation or warranty and shall have no liability to any grantee under the Plan or any other Person with respect to any penalties or taxes under Section 409A that
are, or may be, imposed with respect to any Award. 
 SECTION 12. AMENDMENTS AND TERMINATION 

The Board may, at any time, amend or discontinue the Plan and the Committee may, at any time, amend or cancel any outstanding Award for the
purpose of satisfying changes in law or for any other lawful purpose, but no such action shall adversely affect rights under any outstanding Award without the consent of the holder of the Award. The Committee may exercise its discretion to reduce
the exercise price of outstanding Stock Options or effect repricing through cancellation of outstanding Stock Options and by granting such holders new Awards in replacement of the cancelled Stock Options. To the extent determined by the Committee to
be required either by the Code to ensure that Incentive Stock Options granted under the Plan are qualified under Section 422 of the Code or otherwise, Plan amendments shall be subject to approval by the Company stockholders entitled to vote at
a meeting of stockholders. Nothing in this Section 12 shall limit the Board’s or Committee’s authority to take any action permitted pursuant to Section 3(c). The Board reserves the right to amend the Plan and/or the terms of any
outstanding Stock Options to the extent reasonably necessary to comply with the requirements of the exemption pursuant to paragraph (f)(4) of Rule 12h-1 of the Exchange Act. 

SECTION 13. STATUS OF PLAN 
 With respect
to the portion of any Award that has not been exercised and any payments in cash, Stock or other consideration not received by a grantee, a grantee shall have no rights greater than those of a general creditor of the Company unless the Committee
shall otherwise expressly so determine in connection with any Award. 

  
 17 

 SECTION 14. GENERAL PROVISIONS 

(a) No Distribution; Compliance with Legal Requirements. The Committee may require each person acquiring Shares pursuant to an Award to
represent to and agree with the Company in writing that such person is acquiring the Shares without a view to distribution thereof. No Shares shall be issued pursuant to an Award until all applicable securities law and other legal and stock exchange
or similar requirements have been satisfied. The Committee may require the placing of such stop-orders and restrictive legends on certificates for Stock and Awards as it deems appropriate. 

(b) Delivery of Stock Certificates. Stock certificates to grantees under the Plan shall be deemed delivered for all purposes when the
Company or a stock transfer agent of the Company shall have mailed such certificates in the United States mail, addressed to the grantee, at the grantee’s last known address on file with the Company; provided that stock certificates to be held
in escrow pursuant to Section 9 of the Plan shall be deemed delivered when the Company shall have recorded the issuance in its records. Uncertificated Stock shall be deemed delivered for all purposes when the Company or a stock transfer agent
of the Company shall have given to the grantee by electronic mail (with proof of receipt) or by United States mail, addressed to the grantee, at the grantee’s last known address on file with the Company, notice of issuance and recorded the
issuance in its records (which may include electronic “book entry” records). 
 (c) No Employment Rights. The
adoption of the Plan and the grant of Awards do not confer upon any Person any right to continued employment or Service Relationship with the Company or any Subsidiary. 

(d) Trading Policy Restrictions. Option exercises and other Awards under the Plan shall be subject to the Company’s insider trading
policy-related restrictions, terms and conditions as may be established by the Committee, or in accordance with policies set by the Committee, from time to time. 

(e) Designation of Beneficiary. Each grantee to whom an Award has been made under the Plan may designate a beneficiary or beneficiaries
to exercise any Award on or after the grantee’s death or receive any payment under any Award payable on or after the grantee’s death. Any such designation shall be on a form provided for that purpose by the Committee and shall not be
effective until received by the Committee. If no beneficiary has been designated by a deceased grantee, or if the designated beneficiaries have predeceased the grantee, the beneficiary shall be the grantee’s estate. 

(f) Legend. Any certificate(s) representing the Shares shall carry substantially the following legend (and with respect to
uncertificated Stock, the book entries evidencing such shares shall contain the following notation): 
 The transferability of this
certificate and the shares of stock represented hereby are subject to the restrictions, terms and conditions (including repurchase and restrictions against transfers) contained in the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan and any
agreements entered into thereunder by and between the company and the holder of this certificate (a copy of which is available at the offices of the company for examination). 

  
 18 

 (g) Information to Holders of Options. In the event the Company is relying on the
exemption from the registration requirements of Section 12(g) of the Exchange Act contained in paragraph (f)(1) of Rule 12h-1 of the Exchange Act, the Company shall provide the information described in
Rule 701(e)(3), (4) and (5) of the Securities Act to all holders of Options in accordance with the requirements thereunder. The foregoing notwithstanding, the Company shall not be required to provide such information unless the optionholder has
agreed in writing, on a form prescribed by the Company, to keep such information confidential. 
 SECTION 15. EFFECTIVE DATE OF PLAN 

The Plan shall become effective upon adoption by the Board and shall be approved by stockholders in accordance with applicable state law and
the Company’s articles of incorporation and bylaws within 12 months thereafter. If the stockholders fail to approve the Plan within 12 months after its adoption by the Board of Directors, then any Awards granted or sold under the Plan shall be
rescinded and no additional grants or sales shall thereafter be made under the Plan. Subject to such approval by stockholders and to the requirement that no Shares may be issued hereunder prior to such approval, Stock Options and other Awards may be
granted hereunder on and after adoption of the Plan by the Board. No grants of Stock Options and other Awards may be made hereunder after the tenth anniversary of the date the Plan is adopted by the Board or the date the Plan is approved by the
Company’s stockholders, whichever is earlier. 
 SECTION 16. GOVERNING LAW 

This Plan, all Awards and any controversy arising out of or relating to this Plan and all Awards shall be governed by and construed in
accordance with the General Corporation Law of the State of Delaware as to matters within the scope thereof, and as to all other matters shall be governed by and construed in accordance with the internal laws of the State of 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. 
  

			
	    DATE ADOPTED BY THE BOARD OF DIRECTORS:	  	September 7, 2018
		
	    DATE APPROVED BY THE STOCKHOLDERS:	  	September 7, 2018

  
 19 

 CABALETTA BIO, INC. 

AMENDMENT NO. 1 TO THE 

2018 STOCK OPTION AND GRANT PLAN 

The Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the “Plan”) is hereby amended by the Board of Directors and stockholders
of Cabaletta Bio, Inc., a Delaware corporation, as follows: 
 The first sentence of Section 3(a) of the Plan is hereby amended by
deleting it and replacing it with the following: 
 “Stock Issuable. The maximum number of Shares reserved and available for
issuance under the Plan shall be 2,727,000 Shares, subject to adjustment as provided in Section 3(b). For purposes of this limitation, the Shares underlying any Awards that are forfeited, canceled, reacquired by the Company prior to vesting,
satisfied without the issuance of Stock or otherwise terminated (other than by exercise) and Shares that are withheld upon exercise of an Option or settlement of an Award to cover the exercise price or tax withholding shall be added back to the
Shares available for issuance under the Plan. Subject to such overall limitations, Shares may be issued up to such maximum number pursuant to any type or types of Award, and no more than 3,227,000 Shares may be issued pursuant to Incentive Stock
Options. The Shares available for issuance under the Plan may be authorized but unissued Shares or Shares reacquired by the Company.” 
  

			
	ADOPTED BY BOARD OF DIRECTORS:	  	October 10, 2018
		
	ADOPTED BY STOCKHOLDERS:	  	October 10, 2018

 CABALETTA BIO, INC. 

AMENDMENT NO. 2 TO THE 

2018 STOCK OPTION AND GRANT PLAN 

The Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the “Plan”) is hereby amended by the Board of Directors and
stockholders of Cabaletta Bio, Inc., a Delaware corporation, as follows: 
 The first sentence of Section 3(a) of the Plan is hereby
amended by deleting it and replacing it with the following: 
 “Stock Issuable. The maximum number of Shares reserved and
available for issuance under the Plan shall be 3,870,680 Shares, subject to adjustment as provided in Section 3(b). For purposes of this limitation, the Shares underlying any Awards that are forfeited, canceled, reacquired by the Company prior
to vesting, satisfied without the issuance of Stock or otherwise terminated (other than by exercise) and Shares that are withheld upon exercise of an Option or settlement of an Award to cover the exercise price or tax withholding shall be added back
to the Shares available for issuance under the Plan. Subject to such overall limitations, Shares may be issued up to such maximum number pursuant to any type or types of Award, and no more than 4,370,680 Shares may be issued pursuant to Incentive
Stock Options. The Shares available for issuance under the Plan may be authorized but unissued Shares or Shares reacquired by the Company.” 
  

			
	 ADOPTED BY BOARD OF DIRECTORS:
	 	 July 21, 2019

		
	 ADOPTED BY STOCKHOLDERS:
	 	 July 26, 2019

 INCENTIVE STOCK OPTION GRANT NOTICE 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

Pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the “Plan”), Cabaletta Bio, Inc., a Delaware corporation
(together with any successor, the “Company”), has granted to the individual named below, an option (the “Stock Option”) to purchase on or prior to the Expiration Date, or such earlier date as is specified herein, all or any part
of the number of shares of Common Stock, par value $0.00001 per share (“Common Stock”), of the Company indicated below (the “Shares”), at the Option Exercise Price per share, subject to the terms and conditions set forth in this
Incentive Stock Option Grant Notice (the “Grant Notice”), the attached Incentive Stock Option Agreement (the “Agreement”) and the Plan. This Stock Option is intended to qualify as an “incentive stock option” as defined
in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time (the “Code”). To the extent that any portion of the Stock Option does not so qualify, it shall be deemed a
non-qualified stock option. 
  

			
	Name of Optionee:	  	                         (the “Optionee”)
		
	No. of Shares:	  	                         Shares of Common Stock
		
	Grant Date:	  	                                    

		
	Vesting Commencement Date:	  	                         (the “Vesting Commencement Date”)
		
	Expiration Date:	  	                         (the “Expiration Date”)
		
	Option Exercise Price/Share:	  	$                         (the “Option Exercise Price”)
		
	Vesting Schedule:	  	[25 percent of the Shares shall vest and become exercisable on the first anniversary of the Vesting Commencement Date; provided that the Optionee continues to have a Service Relationship with the Company at such time.
Thereafter, the remaining 75 percent of the Shares shall vest and become exercisable in 36 equal monthly installments following the first anniversary of the Vesting Commencement Date, provided the Optionee continues to have a Service
Relationship with the Company on each vesting date. Notwithstanding anything in the Agreement to the contrary, in the case of a Sale Event, this Stock Option and the Shares shall be treated as provided in Section 3(c) of the Plan.]

 Attachments: Incentive Stock Option Agreement, 2018 Stock Option and Grant Plan 

 INCENTIVE STOCK OPTION AGREEMENT 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

All capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Grant Notice and the Plan.

 1. Vesting, Exercisability and Termination. 

(a) No portion of this Stock Option may be exercised until such portion shall have vested and become exercisable. 

(b) Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting schedule
hereunder, this Stock Option shall be vested and exercisable on the respective dates indicated below: 
 (i) This Stock
Option shall initially be unvested and unexercisable. 
 (ii) This Stock Option shall vest and become exercisable in
accordance with the Vesting Schedule set forth in the Grant Notice. 
 (c) Termination. Except as may otherwise be provided by the
Committee, if the Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter
terminate subject, in each case, to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If
the Optionee’s Service Relationship terminates by reason of such Optionee’s death or Disability, this Stock Option may be exercised, to the extent exercisable on the date of such termination, by the Optionee, the Optionee’s legal
representative or legatee for a period of 12 months from the date of death or Disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
Disability, and unless otherwise determined by the Committee, this Stock Option may be exercised, to the extent exercisable on the date of termination, for a period of 90 days from the date of termination or until the Expiration Date, if earlier;
provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately upon the date of such termination. 

For purposes hereof, the Committee’s determination of the reason for termination of the Optionee’s Service Relationship shall be
conclusive and binding on the Optionee and his or her representatives or legatees. Any portion of this Stock Option that is not vested and exercisable on the date of termination of the Service Relationship shall terminate immediately and be null and
void. 

  
 2 

 (d) It is understood and intended that this Stock Option is intended to qualify as an
“incentive stock option” as defined in Section 422 of the Code to the extent permitted under applicable law. Accordingly, the Optionee understands that in order to obtain the benefits of an incentive stock option under
Section 422 of the Code, no sale or other disposition may be made of Shares for which incentive stock option treatment is desired within the one-year period beginning on the day after the day of the
transfer of such Shares to him or her, nor within the two-year period beginning on the day after Grant Date of this Stock Option and further that this Stock Option must be exercised within three months after
termination of employment as an employee (or 12 months in the case of death or disability) to qualify as an incentive stock option. If the Optionee disposes (whether by sale, gift, transfer or otherwise) of any such Shares within either of these
periods, he or she will notify the Company within 30 days after such disposition. The Optionee also agrees to provide the Company with any information concerning any such dispositions required by the Company for tax purposes. Further, to the extent
this Stock Option and any other incentive stock options of the Optionee having an aggregate Fair Market Value in excess of $100,000 (determined as of the Grant Date) first become exercisable in any year, such options will not qualify as incentive
stock options. 
 2. Exercise of Stock Option. 

(a) The Optionee may exercise this Stock Option only in the following manner: Prior to the Expiration Date, the Optionee may deliver a Stock
Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some or all of the Shares with respect to which this Stock Option is then exercisable. Such notice shall
specify the number of Shares to be purchased. Payment of the purchase price may be made by one or more of the methods described in Section 5 of the Plan, subject to the limitations contained in such Section of the Plan, including the
requirement that the Committee specifically approve in advance certain payment methods. 
 (b) Notwithstanding any other provision hereof or
of the Plan, no portion of this Stock Option shall be exercisable after the Expiration Date. 
 3. Incorporation of Plan.
Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan. 

4. Transferability of Stock Option. This Stock Option is personal to the Optionee and is not transferable by the Optionee in any manner
other than by will or by the laws of descent and distribution. The Stock Option may be exercised during the Optionee’s lifetime only by the Optionee (or by the Optionee’s guardian or personal representative in the event of the
Optionee’s incapacity). The Optionee may elect to designate a beneficiary by providing written notice of the name of such beneficiary to the Company, and may revoke or change such designation at any time by filing written notice of revocation
or change with the Company; such beneficiary may exercise the Optionee’s Stock Option in the event of the Optionee’s death to the extent provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary
predeceases the Optionee, the legal representative of the Optionee may exercise this Stock Option to the extent provided herein in the event of the Optionee’s death. 

  
 3 

 5. Restrictions on Transfer of Shares. The Shares acquired upon exercise of the Stock
Option shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan. 

6. Miscellaneous Provisions. 

(a) Equitable Relief. The parties hereto agree and declare that legal remedies may be inadequate to enforce the provisions of this
Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement. 

(b) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reincorporation,
reclassification, stock dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for a different number or kind of securities of the
Company, the restrictions contained in this Agreement shall apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of his or her ownership of, this Stock Option or Shares
acquired pursuant thereto. 
 (c) Change and Modifications. This Agreement may not be orally changed, modified or terminated, nor
shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Optionee. 

(d) Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware, applied
without regard to conflict of law principles. 
 (e) Headings. The headings are intended only for convenience in finding the subject
matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 
 (f)
Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination shall in no manner affect the legality or enforceability of any other provision hereof. 

(g) Notices. All notices, requests, consents and other communications shall be in writing and be deemed given when delivered personally,
by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the Company or the Optionee shall be addressed as set forth underneath their signatures below, or to such other
address or addresses as may have been furnished by such party in writing to the other. 
 (h) Benefit and Binding Effect. This
Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their respective successors, assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all
the rights of the Company hereunder to the extent of such assignment. 

  
 4 

 (i) Counterparts. For the convenience of the parties and to facilitate execution,
this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 

(j) Integration. This Agreement constitutes the entire agreement between the parties with respect to this Stock Option and supersedes
all prior agreements and discussions between the parties concerning such subject matter. 
 7. Dispute Resolution. 

(a) Except as provided below, any dispute arising out of or relating to the Plan or this Stock Option, this Agreement, or the breach,
termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the
“J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 16, and judgment upon the award rendered by the arbitrators may be entered by any court having jurisdiction thereof. The place
of arbitration shall be Pennsylvania. 
 (b) The arbitration shall commence within 60 days of the date on which a written demand for
arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to
three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The Company, the
Optionee, each party to the Agreement and any other holder of Shares issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This Section 7 applies
equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited purpose of avoiding
immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States District Court
of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees 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 

  
 5 

 from attachment or execution (except as protected by applicable law), 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, and (iii) hereby waives and agrees not to seek any
review by any court of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be given.
Each Party agrees that its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or proceeding
may be enforced in other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 

8. Waiver of Statutory Information Rights. The Optionee understands and agrees that, but for the waiver made herein, the Optionee would
be entitled, upon written demand under oath stating the purpose thereof, to inspect for any proper purpose, and to make copies and extracts from, the Company’s stock ledger, a list of its stockholders, and its other books and records, and the
books and records of subsidiaries of the Company, if any, under the circumstances and in the manner provided in Section 220 of the General Corporation Law of Delaware (any and all such rights, and any and all such other rights of the Optionee
as may be provided for in Section 220, the “Inspection Rights”). In light of the foregoing, until the first sale of Stock of the Company to the general public pursuant to a registration statement filed with and declared effective by
the Securities and Exchange Commission under the Securities Act, the Optionee hereby unconditionally and irrevocably waives the Inspection Rights, whether such Inspection Rights would be exercised or pursued directly or indirectly pursuant to
Section 220 or otherwise, and covenants and agrees 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. The foregoing waiver shall not affect any rights of a director, in his or her capacity as such, under Section 220. The foregoing waiver shall not apply to any contractual inspection rights of the Optionee under
any other written agreement between the Optionee and the Company. 
 [SIGNATURE PAGE FOLLOWS] 

  
 6 

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	CABALETTA BIO, INC.
		
	By:	 	  

		 	Name:
		 	Title:
	
	 Address:
  

Cabaletta Bio, Inc.
 c/o Steven Nichtberger

501 Northwick Lane

	Villanova, PA 19085

 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that this Stock Option is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan, the Grant Notice and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS SET FORTH IN SECTION 7 AND THE WAIVER OF STATUTORY INFORMATION RIGHTS SET FORTH IN SECTION 8 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 

 

	
	 OPTIONEE:
  

	 Name:
  

Address:
  

 
  

  
 7 

	
	SPOUSE’S CONSENT
	 I acknowledge that I have read the foregoing Incentive Stock Option Agreement and understand the contents thereof.

 

  
 8 

 
	
	 DESIGNATED BENEFICIARY:
  

	
	 Beneficiary’s Address:
  

 
  

  
 9 

 Appendix A 

STOCK OPTION EXERCISE NOTICE 
 Cabaletta
Bio, Inc. 
 Attention: 
 Pursuant to the terms
of the grant notice and stock option agreement between the undersigned and Cabaletta Bio, Inc. (the “Company”) dated                  (the
“Agreement”) under the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan, I,                 , hereby [Circle One] partially/fully exercise such
option by including herein payment in the amount of $                 representing the purchase price for
                 Shares. I have chosen the following form(s) of payment: 

 

					
	            [    ]	  	1.	  	Cash
			
	            [    ]	  	2.	  	Certified or bank check payable to Cabaletta Bio, Inc.
			
	            [    ]	  	3.	  	 Other (as referenced in the Agreement and described in the Plan (please describe))

                          
                                         
                                         
        .

 In connection with my exercise of the option as set forth above, I hereby represent and warrant to the
Company as follows: 
 (i) I am purchasing the Shares for my own account for investment only, and not for resale or with a
view to the distribution thereof. 
 (ii) I have had such an opportunity as I have deemed adequate to obtain from the Company
such information as is necessary to permit me to evaluate the merits and risks of my investment in the Company and have consulted with my own advisers with respect to my investment in the Company. 

(iii) I have sufficient experience in business, financial and investment matters to be able to evaluate the risks involved in
the purchase of the Shares and to make an informed investment decision with respect to such purchase. 
 (iv) I can afford a
complete loss of the value of the Shares and am able to bear the economic risk of holding such Shares for an indefinite period of time. 

(v) I understand that the Shares may not be registered under the Securities Act of 1933 (it being understood that the Shares
are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold or otherwise transferred or disposed of in the absence of an effective
registration statement under the Securities Act of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing Shares
will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Shares will include similar restrictive notations. 

  
 10 

 (vi) I have read and understand the Plan and acknowledge and agree that the
Shares are subject to all of the relevant terms of the Plan, including without limitation, the transfer restrictions set forth in Section 9 of the Plan. 

(vii) I understand and agree that the Company has a right of first refusal with respect to the Shares pursuant to
Section 9(b) of the Plan. 
 (viii) I understand and agree that the Company has certain repurchase rights with respect
to the Shares pursuant to Section 9(c) of the Plan. 
 (ix) I understand and agree that I may not sell or otherwise
transfer or dispose of the Shares for a period of time following the effective date of a public offering by the Company as described in Section 9(f) of the Plan. 

(x) I understand and agree to the waiver of statutory information rights as set forth in Section 8 of the Agreement. 

 

	
	Sincerely yours,
	
	   

	 Name:
  

Address:

	
	   

	
	   

	
	   

	
	Date:
                                         
                               

  
 11 

 NON-QUALIFIED STOCK OPTION GRANT NOTICE 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

Pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the “Plan”), Cabaletta Bio, Inc., a Delaware corporation
(together with any successor, the “Company”), has granted to the individual named below, an option (the “Stock Option”) to purchase on or prior to the Expiration Date, or such earlier date as is specified herein, all or any part
of the number of shares of Common Stock, par value $0.00001 per share (“Common Stock”), of the Company indicated below (the “Shares”), at the Option Exercise Price per share, subject to the terms and conditions set forth in this Non-Qualified Stock Option Grant Notice (the “Grant Notice”), the attached Non-Qualified Stock Option Agreement (the “Agreement”) and the Plan. This Stock
Option is not intended to qualify as an “incentive stock option” as defined in Section 422(b) of the Internal Revenue Code of 1986, as amended from time to time (the “Code”). 

 

			
	Name of Optionee:	  	                             (the “Optionee”)
		
	No. of Shares:	  	                             Shares of Common Stock
		
	Grant Date:	  	                            
		
	Vesting Commencement Date:	  	                             (the “Vesting Commencement Date”)
		
	Expiration Date:	  	                             (the “Expiration Date”)
		
	Option Exercise Price/Share:	  	$                             (the “Option Exercise Price”)
		
	Vesting Schedule:	  	[25 percent of the Shares shall vest and become exercisable on the first anniversary of the Vesting Commencement Date; provided that the Optionee continues to have a Service Relationship with the Company at such time.
Thereafter, the remaining 75 percent of the Shares shall vest and become exercisable in 36 equal monthly installments following the first anniversary of the Vesting Commencement Date, provided the Optionee continues to have a Service
Relationship with the Company on each vesting date. Notwithstanding anything in the Agreement to the contrary, in the case of a Sale Event, this Stock Option and the Shares shall be treated as provided in Section 3(c) of the
Plan.]

 Attachments: Non-Qualified Stock Option Agreement, 2018 Stock Option and Grant
Plan 

 NON-QUALIFIED STOCK OPTION AGREEMENT 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

All capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Grant Notice and the Plan.

 1. Vesting, Exercisability and Termination. 

(a) No portion of this Stock Option may be exercised until such portion shall have vested and become exercisable. 

(b) Except as set forth below, and subject to the determination of the Committee in its sole discretion to accelerate the vesting schedule
hereunder, this Stock Option shall be vested and exercisable on the respective dates indicated below: 
 (i) This Stock
Option shall initially be unvested and unexercisable. 
 (ii) This Stock Option shall vest and become exercisable in
accordance with the Vesting Schedule set forth in the Grant Notice. 
 (c) Termination. Except as may otherwise be provided by the
Committee, if the Optionee’s Service Relationship is terminated, the period within which to exercise this Stock Option will be subject to earlier termination as set forth below (and if not exercised within such period, shall thereafter
terminate subject, in each case, to Section 3(c) of the Plan): 
 (i) Termination Due to Death or Disability. If
the Optionee’s Service Relationship terminates by reason of such Optionee’s death or Disability, this Stock Option may be exercised, to the extent exercisable on the date of such termination, by the Optionee, the Optionee’s legal
representative or legatee for a period of 12 months from the date of death or Disability or until the Expiration Date, if earlier. 

(ii) Other Termination. If the Optionee’s Service Relationship terminates for any reason other than death or
Disability, and unless otherwise determined by the Committee, this Stock Option may be exercised, to the extent exercisable on the date of termination, for a period of 90 days from the date of termination or until the Expiration Date, if earlier;
provided however, if the Optionee’s Service Relationship is terminated for Cause, this Stock Option shall terminate immediately upon the date of such termination. 

For purposes hereof, the Committee’s determination of the reason for termination of the Optionee’s Service Relationship shall be
conclusive and binding on the Optionee and his or her representatives or legatees and any Permitted Transferee. Any portion of this Stock Option that is not vested and exercisable on the date of termination of the Service Relationship shall
terminate immediately and be null and void. 

  
 2 

 2. Exercise of Stock Option. 

(a) The Optionee may exercise this Stock Option only in the following manner: Prior to the Expiration Date, the Optionee may deliver a Stock
Option exercise notice (an “Exercise Notice”) in the form of Appendix A hereto indicating his or her election to purchase some or all of the Shares with respect to which this Stock Option is then exercisable. Such notice shall
specify the number of Shares to be purchased. Payment of the purchase price may be made by one or more of the methods described in Section 5 of the Plan, subject to the limitations contained in such Section of the Plan, including the
requirement that the Committee specifically approve in advance certain payment methods. 
 (b) Notwithstanding any other provision hereof or
of the Plan, no portion of this Stock Option shall be exercisable after the Expiration Date. 
 3. Incorporation of Plan.
Notwithstanding anything herein to the contrary, this Stock Option shall be subject to and governed by all the terms and conditions of the Plan. 

4. Transferability of Stock Option. This Stock Option is personal to the Optionee and is not transferable by the Optionee in any manner
other than by will or by the laws of descent and distribution. The Stock Option may be exercised during the Optionee’s lifetime only by the Optionee (or by the Optionee’s guardian or personal representative in the event of the
Optionee’s incapacity). The Optionee may elect to designate a beneficiary by providing written notice of the name of such beneficiary to the Company, and may revoke or change such designation at any time by filing written notice of revocation
or change with the Company; such beneficiary may exercise the Optionee’s Stock Option in the event of the Optionee’s death to the extent provided herein. If the Optionee does not designate a beneficiary, or if the designated beneficiary
predeceases the Optionee, the legal representative of the Optionee may exercise this Stock Option to the extent provided herein in the event of the Optionee’s death. 

5. Restrictions on Transfer of Shares. The Shares acquired upon exercise of the Stock Option shall be subject to certain transfer
restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan. 
 6.
Miscellaneous Provisions. 
 (a) Equitable Relief. The parties hereto agree and declare that legal remedies may be inadequate
to enforce the provisions of this Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement. 

(b) Adjustments for Changes in Capital Structure. If, as a result of any reorganization, recapitalization, reincorporation,
reclassification, stock dividend, stock split, reverse stock split or other similar change in the Common Stock, the outstanding shares of Common Stock are increased or decreased or are exchanged for a different number or kind of securities of the
Company, the restrictions contained in this Agreement shall apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of his or her ownership of, this Stock Option or Shares
acquired pursuant thereto. 

  
 3 

 (c) Change and Modifications. This Agreement may not be orally changed, modified or
terminated, nor shall any oral waiver of any of its terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Optionee. 

(d) Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware, applied
without regard to conflict of law principles. 
 (e) Headings. The headings are intended only for convenience in finding the subject
matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 
 (f)
Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination shall in no manner affect the legality or enforceability of any other provision hereof. 

(g) Notices. All notices, requests, consents and other communications shall be in writing and be deemed given when delivered personally,
by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the Company or the Optionee shall be addressed as set forth underneath their signatures below, or to such other
address or addresses as may have been furnished by such party in writing to the other. 
 (h) Benefit and Binding Effect. This
Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their respective successors, assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all
the rights of the Company hereunder to the extent of such assignment. 
 (i) Counterparts. For the convenience of the parties and to
facilitate execution, this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 

(j) Integration. This Agreement constitutes the entire agreement between the parties with respect to this Stock Option and supersedes
all prior agreements and discussions between the parties concerning such subject matter. 
 7. Dispute Resolution. 

(a) Except as provided below, any dispute arising out of or relating to the Plan or this Stock Option, this Agreement, or the breach,
termination or validity of the Plan, this Stock Option or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the
“J.A.M.S. Rules”). The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1-16, and judgment upon the award rendered by the arbitrators may be entered by any court
having jurisdiction thereof. The place of arbitration shall be Pennsylvania. 

  
 4 

 (b) The arbitration shall commence within 60 days of the date on which a written demand for
arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to
three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The Company, the
Optionee, each party to the Agreement and any other holder of Shares issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This Section 7 applies
equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited purpose of avoiding
immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States District Court
of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees 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 (except as protected by applicable law), 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, and (iii) hereby waives and agrees not to seek any review by any court
of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be given. Each Party agrees that
its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or proceeding may be enforced in
other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 

8. Waiver of Statutory Information Rights. The Optionee understands and agrees that, but for the waiver made herein, the Optionee would
be entitled, upon written demand under oath stating the purpose thereof, to inspect for any proper purpose, and to make copies and extracts from, the Company’s stock ledger, a list of its stockholders, and its other books and records, and the
books and records of subsidiaries of the Company, if any, under the circumstances and in the manner provided in Section 220 of the General Corporation Law of 

  
 5 

 Delaware (any and all such rights, and any and all such other rights of the Optionee as may be provided for
in Section 220, the “Inspection Rights”). In light of the foregoing, until the first sale of Stock of the Company to the general public pursuant to a registration statement filed with and declared effective by the Securities and
Exchange Commission under the Securities Act, the Optionee hereby unconditionally and irrevocably waives the Inspection Rights, whether such Inspection Rights would be exercised or pursued directly or indirectly pursuant to Section 220 or
otherwise, and covenants and agrees 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. The foregoing waiver shall not affect any rights of a director, in his or her capacity as such, under Section 220. The foregoing waiver shall not apply to any contractual inspection rights of the Optionee under any other
written agreement between the Optionee and the Company. 
 [SIGNATURE PAGE FOLLOWS] 

  
 6 

 The foregoing Agreement is hereby accepted and the terms and conditions thereof hereby
agreed to by the undersigned as of the date first above written. 
  

			
	CABALETTA BIO, INC.
		
	By:	 	 
		 	Name:
		 	Title:
	
	Address:
	
	 Cabaletta Bio, Inc.
 c/o Steven
Nichtberger
 501 Northwick Lane

	Villanova, PA 19085

 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof, and understands that this Stock Option is subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan, the Grant Notice and this Agreement, SPECIFICALLY
INCLUDING THE ARBITRATION PROVISIONS SET FORTH IN SECTION 7 AND THE WAIVER OF STATUTORY INFORMATION RIGHTS SET FORTH IN SECTION 8 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 

 

	
	 OPTIONEE:
  

	 Name:
  

Address:
  

 
  

  
 7 

	
	SPOUSE’S CONSENT
	 I acknowledge that I have read the foregoing Non-Qualified Stock Option Agreement and understand the contents thereof.

 

  
 8 

 
	
	 DESIGNATED BENEFICIARY:
  

 

	 Beneficiary’s Address:
  

 
  

  
 9 

 Appendix A 

STOCK OPTION EXERCISE NOTICE 

Cabaletta Bio, Inc. 
 Attention: 

Pursuant to the terms of the grant notice and stock option agreement between the undersigned and Cabaletta Bio, Inc. (the “Company”)
dated                  (the “Agreement”) under the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan, I,
                , hereby [Circle One] partially/fully exercise such option by including herein payment in the amount of
$                 representing the purchase price for                 
Shares. I have chosen the following form(s) of payment: 
  

					
	[    ]	 	1.	  	Cash
			
	[    ]	 	2.	  	Certified or bank check payable to Cabaletta Bio, Inc.
			
	[    ]	 	3.	  	 Other (as referenced in the Agreement and described in the Plan (please describe))

                          
                                         
                                         
            .

 In connection with my exercise of the option as set forth above, I hereby represent and warrant to the Company
as follows: 
 (i) I am purchasing the Shares for my own account for investment only, and not for resale or with a view to
the distribution thereof. 
 (ii) I have had such an opportunity as I have deemed adequate to obtain from the Company such
information as is necessary to permit me to evaluate the merits and risks of my investment in the Company and have consulted with my own advisers with respect to my investment in the Company. 

(iii) I have sufficient experience in business, financial and investment matters to be able to evaluate the risks involved in
the purchase of the Shares and to make an informed investment decision with respect to such purchase. 
 (iv) I can afford a
complete loss of the value of the Shares and am able to bear the economic risk of holding such Shares for an indefinite period of time. 

(v) I understand that the Shares may not be registered under the Securities Act of 1933 (it being understood that the Shares
are being issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold or otherwise transferred or disposed of in the absence of an effective
registration statement under the Securities Act of 1933 and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirement thereof). I further acknowledge that certificates representing Shares
will bear restrictive legends reflecting the foregoing and/or that book entries for uncertificated Shares will include similar restrictive notations. 

  
 10 

 (vi) I have read and understand the Plan and acknowledge and agree that the
Shares are subject to all of the relevant terms of the Plan, including without limitation, the transfer restrictions set forth in Section 9 of the Plan. 

(vii) I understand and agree that the Company has a right of first refusal with respect to the Shares pursuant to
Section 9(b) of the Plan. 
 (viii) I understand and agree that the Company has certain repurchase rights with respect
to the Shares pursuant to Section 9(c) of the Plan. 
 (ix) I understand and agree that I may not sell or otherwise
transfer or dispose of the Shares for a period of time following the effective date of a public offering by the Company as described in Section 9(f) of the Plan. 

(x) I understand and agree to the waiver of statutory information rights as set forth in Section 8 of the Agreement. 

 

	
	Sincerely yours,
	
	   

	 Name:
  

Address:

	
	   

	
	   

	
	   

	
	Date:
                                         
                                       

  
 11 

 RESTRICTED STOCK AWARD NOTICE 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

Pursuant to the Cabaletta Bio, Inc. 2018 Stock Option and Grant Plan (the “Plan”), Cabaletta Bio, Inc., a Delaware corporation
(together with any successor, the “Company”), hereby grants, sells and issues to the individual named below, the Shares at the Per Share Purchase Price, subject to the terms and conditions set forth in this Restricted Stock Award Notice
(the “Award Notice”), the attached Restricted Stock Agreement (the “Agreement”) and the Plan. The Grantee agrees to the provisions set forth herein and acknowledges that each such provision is a material condition of the
Company’s agreement to issue and sell the Shares to him or her. The Company hereby acknowledges receipt of $[            ] in full payment for the Shares. All
references to share prices and amounts herein shall be equitably adjusted to reflect stock splits, stock dividends, recapitalizations, mergers, reorganizations and similar changes affecting the capital stock of the Company, and any shares of capital
stock of the Company received on or in respect of Shares in connection with any such event (including any shares of capital stock or any right, option or warrant to receive the same or any security convertible into or exchangeable for any such
shares or received upon conversion of any such shares) shall be subject to this Agreement on the same basis and extent at the relevant time as the Shares in respect of which they were issued, and shall be deemed Shares as if and to the same extent
they were issued at the date hereof. 
  

			
	Name of Grantee:	  	                                 (the
“Grantee”)
		
	No. of Shares:	  	                         Shares of Common Stock (the “Shares”)
		
	Grant Date:	  	                                    ,
        
		
	Date of Purchase of Shares:	  	                                    ,
        
		
	Vesting Commencement Date:	  	                        ,          (the “Vesting
Commencement Date”) Per
		
	Share Purchase Price:	  	$                         (the “Per Share Purchase Price”)
		
	Vesting Schedule:	  	[25 percent of the Shares shall vest on the first anniversary of the Vesting Commencement Date; provided that the Grantee continues to have a Service Relationship with the Company at such time. Thereafter, the remaining
75 percent of the Shares shall vest in 36 equal monthly installments following the first anniversary of the Vesting Commencement Date, provided the Grantee continues to have a Service Relationship with the Company at such time. Notwithstanding
anything in the Agreement to the contrary in the case of a Sale Event, the Shares of Restricted Stock shall be treated as provided in Section 3(c) of the Plan.]

 Attachments: Restricted Stock Agreement, 2018 Stock Option and Grant Plan 

  
 2 

 RESTRICTED STOCK AGREEMENT 

UNDER THE CABALETTA BIO, INC. 

2018 STOCK OPTION AND GRANT PLAN 

All capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Award Notice and the Plan.

 1. Purchase and Sale of Shares; Vesting; Investment Representations. 

(a) Purchase and Sale. The Company hereby sells to the Grantee, and the Grantee hereby purchases from the Company, the number of Shares
set forth in the Award Notice for the Per Share Purchase Price. 
 (b) Vesting. Initially, all of the Shares are non-transferable and subject to a substantial risk of forfeiture and are Shares of Restricted Stock. The risk of forfeiture shall lapse with respect to the Shares on the respective dates indicated on the Vesting
Schedule set forth in the Award Notice. 
 (c) Investment Representations. In connection with the purchase and sale of the Shares
contemplated by Section 1(a) above, the Grantee hereby represents and warrants to the Company as follows: 
 (i) The
Grantee is purchasing the Shares for the Grantee’s own account for investment only, and not for resale or with a view to the distribution thereof. 

(ii) The Grantee has had such an opportunity as he or she has deemed adequate to obtain from the Company such information as is
necessary to permit him or her to evaluate the merits and risks of the Grantee’s investment in the Company and has consulted with the Grantee’s own advisers with respect to the Grantee’s investment in the Company. 

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

(v) The Grantee understands that the Shares are not registered under the Act (it being understood that the Shares are being
issued and sold in reliance on the exemption provided in Rule 701 thereunder) or any applicable state securities or “blue sky” laws and may not be sold or otherwise transferred or disposed of in the absence of an effective registration
statement under the Act and under any applicable state securities or “blue sky” laws (or exemptions from the registration requirements thereof). The Grantee further acknowledges that certificates representing the Shares will bear
restrictive legends reflecting the foregoing and/or that book entries for uncertificated Shares will include similar restrictive notations. 

  
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 (vi) The Grantee has read and understands the Plan and acknowledges and
agrees that the Shares are subject to all of the relevant terms of the Plan, including without limitation, the transfer restrictions set forth in Section 9 of the Plan. 

(vii) The Grantee understands and agrees that the Company has a right of first refusal with respect to the Shares pursuant to
Section 9(b) of the Plan. 
 (viii) The Grantee understands and agree that the Company has certain repurchase rights
with respect to the Shares pursuant to Section 9(c) of the Plan. 
 (ix) The Grantee understands and agrees that the
Grantee may not sell or otherwise transfer or dispose of the Shares for a period of time following the effective date of a public offering by the Company as described in Section 9(f) of the Plan. 

2. Repurchase Right. Upon a Termination Event, the Company shall have the right to repurchase Shares of Restricted Stock that are
unvested as of the date of such Termination Event as set forth in Section 9(c) of the Plan. 
 3. Restrictions on Transfer of
Shares. The Shares (whether or not vested) shall be subject to certain transfer restrictions and other limitations including, without limitation, the provisions contained in Section 9 of the Plan 

4. Incorporation of Plan. Notwithstanding anything herein to the contrary, this Restricted Stock Award shall be subject to and governed
by all the terms and conditions of the Plan. 
 5. Miscellaneous Provisions. 

(a) Record Owner; Dividends. The Grantee and any Permitted Transferees, during the duration of this Agreement, shall be considered the
record owners of and shall be entitled to vote the Shares if and to the extent the Shares are entitled to voting rights. The Grantee and any Permitted Transferees shall be entitled to receive all dividends and any other distributions declared on the
Shares; provided, however, that the Company is under no duty to declare any such dividends or to make any such distribution. 

(b) Section 83(b) Election. The Grantee shall consult with the Grantee’s tax advisor to determine whether it would be appropriate
for the Grantee to make an election under Section 83(b) of the Code with respect to this Award. Any such election must be filed with the Internal Revenue Service within 30 days of the date of this Award. If the Grantee makes an election under
Section 83(b) of the Code, the Grantee shall give prompt notice to the Company (and provide a copy of such election to the Company). A sample Section 83(b) election is attached to this Agreement as Exhibit A. 

  
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 (c) Equitable Relief. The parties hereto agree and declare that legal remedies may be
inadequate to enforce the provisions of this Agreement and that equitable relief, including specific performance and injunctive relief, may be used to enforce the provisions of this Agreement. 

(d) Change and Modifications. This Agreement may not be orally changed, modified or terminated, nor shall any oral waiver of any of its
terms be effective. This Agreement may be changed, modified or terminated only by an agreement in writing signed by the Company and the Grantee. 

(e) Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of Delaware, applied
without regard to conflict of law principles. 
 (f) Headings. The headings are intended only for convenience in finding the subject
matter and do not constitute part of the text of this Agreement and shall not be considered in the interpretation of this Agreement. 
 (g)
Saving Clause. If any provision(s) of this Agreement shall be determined to be illegal or unenforceable, such determination shall in no manner affect the legality or enforceability of any other provision hereof. 

(h) Notices. All notices, requests, consents and other communications shall be in writing and be deemed given when delivered personally,
by telex or facsimile transmission or when received if mailed by first class registered or certified mail, postage prepaid. Notices to the Company or the Grantee shall be addressed as set forth underneath their signatures below, or to such other
address or addresses as may have been furnished by such party in writing to the other. 
 (i) Benefit and Binding Effect. This
Agreement shall be binding upon and shall inure to the benefit of the parties hereto, their respective successors, assigns, and legal representatives. The Company has the right to assign this Agreement, and such assignee shall become entitled to all
the rights of the Company hereunder to the extent of such assignment. 
 (j) Counterparts. For the convenience of the parties and to
facilitate execution, this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document. 

(k) Integration. This Agreement constitutes the entire agreement between the parties with respect to this Award and supersedes all prior
agreements and discussions between the parties concerning such subject matter. 
 6. Dispute Resolution. 

(a) Except as provided below, any dispute arising out of or relating to the Plan or the Shares, this Agreement, or the breach, termination or
validity of the Plan, the Shares or this Agreement, shall be finally settled by binding arbitration conducted expeditiously in accordance with the J.A.M.S./Endispute Comprehensive Arbitration Rules and Procedures (the “J.A.M.S. Rules”).
The arbitration shall be governed by the United States Arbitration Act, 9 U.S.C. Sections 1 - 16, and judgment upon the award rendered by the arbitrators may be entered by any court having jurisdiction thereof. The place of arbitration shall be
Pennsylvania. 

  
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 (b) The arbitration shall commence within 60 days of the date on which a written demand for
arbitration is filed by any party hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may take up to
three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have the power to order the answering of interrogatories or the
response to requests for admission. In connection with any arbitration, each party to the arbitration shall provide to the other, no later than seven business days before the date of the arbitration, the identity of all persons that may testify at
the arbitration and a copy of all documents that may be introduced at the arbitration or considered or used by a party’s witness or expert. The arbitrator’s decision and award shall be made and delivered within six months of the selection
of the arbitrator. The arbitrator’s decision shall set forth a reasoned basis for any award of damages or finding of liability. The arbitrator shall not have power to award damages in excess of actual compensatory damages and shall not multiply
actual damages or award punitive damages, and each party hereby irrevocably waives any claim to such damages. 
 (c) The Company, the
Grantee, each party to the Agreement and any other holder of Shares issued pursuant to this Agreement (each, a “Party”) covenants and agrees that such party will participate in the arbitration in good faith. This Section 6 applies
equally to requests for temporary, preliminary or permanent injunctive relief, except that in the case of temporary or preliminary injunctive relief any party may proceed in court without prior arbitration for the limited purpose of avoiding
immediate and irreparable harm. 
 (d) Each Party (i) hereby irrevocably submits to the jurisdiction of any United States District Court
of competent jurisdiction for the purpose of enforcing the award or decision in any such proceeding, (ii) hereby waives, and agrees 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 (except as protected by applicable law), 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, and (iii) hereby waives and agrees not to seek any review by any court
of any other jurisdiction which may be called upon to grant an enforcement of the judgment of any such court. Each Party hereby consents to service of process by registered mail at the address to which notices are to be given. Each Party agrees that
its, his or her submission to jurisdiction and its, his or her consent to service of process by mail is made for the express benefit of each other Party. Final judgment against any Party in any such action, suit or proceeding may be enforced in
other jurisdictions by suit, action or proceeding on the judgment, or in any other manner provided by or pursuant to the laws of such other jurisdiction. 

  
 6 

 7. Waiver of Statutory Information Rights. The Grantee understands and agrees
that, but for the waiver made herein, the Grantee would be entitled, upon written demand under oath stating the purpose thereof, to inspect for any proper purpose, and to make copies and extracts from, the Company’s stock ledger, a list of its
stockholders, and its other books and records, and the books and records of subsidiaries of the Company, if any, under the circumstances and in the manner provided in Section 220 of the General Corporation Law of Delaware (any and all such
rights, and any and all such other rights of the Grantee as may be provided for in Section 220, the “Inspection Rights”). In light of the foregoing, until the first sale of Stock of the Company to the general public pursuant to a
registration statement filed with and declared effective by the Securities and Exchange Commission under the Securities Act, the Grantee hereby unconditionally and irrevocably waives the Inspection Rights, whether such Inspection Rights would be
exercised or pursued directly or indirectly pursuant to Section 220 or otherwise, and covenants and agrees 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. The foregoing waiver shall not affect any rights of a director, in his or her capacity as such, under Section 220. The foregoing waiver shall not apply to
any contractual inspection rights of the Grantee under any other written agreement between the Grantee and the Company. 
 [SIGNATURE PAGE
FOLLOWS] 

  
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 The foregoing Restricted Stock Agreement is hereby accepted and the terms and conditions
thereof are hereby agreed to by the undersigned as of the date of purchase of Shares above written. 
  

			
	CABALETTA BIO, INC.
		
	By:	 	  

		 	Name:
		 	Title:
	
	 Address:
  

Cabaletta Bio, Inc.
 c/o Steven Nichtberger

501 Northwick Lane

	Villanova, PA 19085

 The undersigned hereby acknowledges receiving and reviewing a copy of the Plan, including, without limitation,
Section 9 thereof and understands that the Shares granted hereby are subject to the terms of the Plan and of this Agreement. This Agreement is hereby accepted, and the terms and conditions of the Plan, the Award Notice and this Agreement,
SPECIFICALLY INCLUDING THE ARBITRATION PROVISIONS SET FORTH IN SECTION 6 AND THE WAIVER OF STATUTORY INFORMATION RIGHTS SET FORTH IN SECTION 7 OF THIS AGREEMENT, are hereby agreed to, by the undersigned as of the date first above written. 

 

	
	 GRANTEE:
  

	 Name:
  

Address:
  

 
  

  
 8 

	
	SPOUSE’S CONSENT
	 I acknowledge that I have read the foregoing Restricted Stock Agreement and understand the contents thereof.

 

  
 9 

 EXHIBIT A 

Section 83(b) Election 

(see attached) 

  
 10EX-10.12

 Exhibit 10.12 

 

			
	

	  	 Tenant: Cabaletta Bio, Inc.

Premises: Cira Centre, Suite 600

 LEASE 

THIS LEASE (“Lease”) is entered into as of February 11, 2019 between BRANDYWINE CIRA, L.P., a Pennsylvania limited
partnership (“Landlord”), and CABALETTA BIO, INC., a Delaware corporation (“Tenant”). 
 In consideration
of the mutual covenants stated below, and intending to be legally bound, Landlord and Tenant covenant and agree as follows: 
 1. KEY
DEFINED TERMS. 
 (a) “Abatement Period” means the period that begins on the Commencement Date and ends on the day
immediately prior to the three (3)-month anniversary of the Commencement Date. Nothing contained herein may be deemed to diminish or relieve Tenant of its obligation to pay in accordance with the terms of this Lease all sums owed by Tenant to
Landlord during the Abatement Period other than Fixed Rent. 
 (b) “Additional Rent” means all rents, costs, and expenses
other than Fixed Rent that Tenant is obligated to pay Landlord pursuant to this Lease. 
 (c) “Broker” means CBRE, Inc. 

(d) “Building” means the building known as Cira Centre located at 2929 Arch Street, Philadelphia, Pennsylvania 19104
containing approximately 730,187 rentable square feet. 
 (e) “Business Hours” means the hours of 8:00 a.m. to
6:00 p.m. on weekdays, and 8:00 a.m. to 1:00 p.m. on Saturdays, excluding Building holidays. 
 (f) “Commencement
Date” means the date that is the earlier of: (i) the date on which Tenant first conducts any business in all or any portion of the Premises; or (ii) Substantial Completion (as defined in Exhibit C). 

(g) “Common Areas” means, to the extent applicable, the lobby, parking facilities, passenger elevators, rooftop terrace,
fitness or health center, plaza and sidewalk areas, multi-tenanted floor restrooms, and other similar areas of unrestricted access at the Project or designated for the benefit of Building tenants, and the areas on multi-tenant floors in the Building
devoted to corridors, elevator lobbies, and other similar facilities serving the Premises. 
 (h) “Expiration Date” means
the last day of the Term, or such earlier date of termination of this Lease pursuant to the terms hereof. 
 (i) “Fixed
Rent” means fixed rent in the amounts set forth below: 

													
	 TIME PERIOD
	  	FIXED RENT PER
R.S.F.	 	  	ANNUALIZED FIXED
RENT	 	  	MONTHLY INSTALLMENT	 
	 Commencement Date -
end of Abatement Period
	  	$	0.00	 	  	$	0.00	 	  	$	0.00	 
	 Fixed Rent Start Date - end of Rent Period 1
	  	$	34.00	 	  	$	260,848.00	 	  	$	21,737.33	 
	 Rent Period 2
	  	$	34.68	 	  	$	266,064.96	 	  	$	22,172.08	 
	 Rent Period 3 - End of Initial Term
	  	$	35.37	 	  	$	271,358.64	 	  	$	22,613.22	 

 (j) “Fixed Rent Start Date” means the day immediately following the end of the Abatement
Period. 
 (k) “Initial Term” means the period commencing on the Commencement Date, and ending at 11:59 p.m. on:
(i) if the Fixed Rent Start Date is the first day of a calendar month, the day immediately prior to the thirty-six (36)-month anniversary of the Fixed Rent Start Date; or (ii) if the Fixed Rent Start Date is not the first day of a
calendar month, the last day of the calendar month containing the thirty-six (36)-month anniversary of the Fixed Rent Start Date. 
 (l)
“Laws” means federal, state, county, and local governmental and municipal laws, statutes, ordinances, rules, regulations, codes, decrees, orders, and other such requirements, and decisions by courts in cases where such decisions are
considered binding precedents in the state or commonwealth in which the Premises are located (“State”), and decisions of federal courts applying the laws of the State, including without limitation Title III of the Americans
with Disabilities Act of 1990,42 U.S.C. §12181 et seq. and its regulations. 
 (m) “Premises” means the space presently
known as Suite 600 in the Building, as shown on Exhibit A attached hereto, which is deemed to contain 7,672 rentable square feet. Landlord represents that, to the best of its knowledge, the Premises consist of 7,672 rentable square
feet. 
 (n) “Project” means the Building, together with the parcel of land owned by Landlord upon which the Building is
located, and all Common Areas. 
 (o) “Rent” means Fixed Rent and Additional Rent. Landlord may apply payments received from
Tenant to any obligations of Tenant then due and owing without regard to any contrary Tenant instructions or requests. Additional Rent shall be paid by Tenant in the same manner as Fixed Rent, without setoff, deduction, or counterclaim (except as
otherwise provided herein). 
 (p) “Rent Period” means, with respect to the first Rent Period, the period that begins on the
Fixed Rent Start Date and ends on the last day of the calendar month preceding the month in which the first anniversary of the Fixed Rent Start Date occurs; thereafter each succeeding Rent Period shall commence on the day following the end of the
preceding Rent Period, and shall extend for twelve (12) consecutive months. 
 (q) “Security Deposit” means $21,737.33.

  
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 (r) “Tenant’s NAICS Code” means Tenant’s six (6)-digit North
American Industry Classification number under the North American Industry Classification System as promulgated by the Executive Office of the President, Office of Management and Budget, which is 325412. 

(s) “Term” means the Initial Term together with any extension of the term of this Lease agreed to by the parties in writing.

 2. PREMISES. Landlord leases to Tenant, and Tenant leases from Landlord, the Premises for the Term subject to the terms and
conditions of this Lease. Except for the representations and warranties of Landlord as set forth in this Lease, Tenant accepts the Premises in their “AS IS”, “WHERE IS”, “WITH ALL FAULTS” condition, except that:
(i) Landlord shall complete the Leasehold Improvements pursuant to Exhibit C attached hereto, and deliver the Premises to Tenant in compliance with all applicable Laws, and with all HVAC, mechanical, plumbing, and electrical systems
serving the Premises in good working order; (ii) Landlord shall remain responsible for any latent defects provided notice of such defect is provided to Landlord within twelve (12) months after the Commencement Date; and (iii) nothing
in this Section shall release Landlord from its repair and other obligations under this Lease. 
 3. TERM. The Term shall commence on
the Commencement Date. The terms and provisions of this Lease are binding on the parties upon Tenant’s and Landlord’s execution of this Lease notwithstanding a later Commencement Date for the Term. The rentable area of the Premises and the
Building on the Commencement Date shall be deemed to be as stated in Section 1. By the Confirmation of Lease Term substantially in the form of Exhibit B attached hereto (“COLT’). Landlord shall notify Tenant
of the Commencement Date and all other matters stated therein. The COLT shall be conclusive and binding on Tenant as to all matters set forth therein unless, within thirty (30) days following delivery of the COLT to Tenant, Tenant contests any
of the matters contained therein by notifying Landlord in writing of Tenant’s objections. 
 4. FIXED RENT: SECURITY DEPOSIT: LATE
FEE. 
 (a) Tenant covenants and agrees to pay to Landlord during the Term, without notice, demand, setoff, deduction, or counterclaim
(except as otherwise provided herein), Fixed Rent in the amounts set forth in Section l(i). The Monthly Installment of Fixed Rent, the monthly amount of Estimated Operating Expenses as set forth in Section 5, and any
estimated amount of utilities as set forth in Section 6, shall be payable to Landlord in advance on or before the first day of each month of the Term. If the Fixed Rent Start Date is not the first day of a calendar month, then the Fixed
Rent due for the partial month commencing on the Fixed Rent Start Date shall be prorated based on the number of days in such month. All Rent payments shall be made by electronic funds transfer as follows (or as otherwise directed in writing by
Landlord to Tenant from time to time): (i) ACH debit of funds, provided Tenant shall first complete Landlord’s then-current forms authorizing Landlord to automatically debit Tenant’s bank account; or (ii) ACH credit of
immediately available funds to an account designated by Landlord. “ACH” means Automated Clearing House network or similar system designated by Landlord. All Rent payments shall include the Building number and the Lease number, which
numbers will be provided to Tenant in the COLT. 

  
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 (b) Contemporaneously with Tenant’s execution and delivery of this Lease, Tenant shall
pay to Landlord the Security Deposit. No interest shall be paid to Tenant on the Security Deposit, and Landlord shall have the right to commingle the Security Deposit with other funds of Landlord. If Tenant fails to perform any of its obligations
under this Lease that are not cured within the applicable notice and/or cure periods provided herein, Landlord may use, apply or retain the whole or any part of the Security Deposit for the payment of: (A) any rent or other sums that Tenant has
not paid when due; (B) any sum expended by Landlord in accordance with the provisions of this Lease; and/or (C) any sum that Landlord expends or is required to expend in connection with an Event of Default (as defined in
Section 17). Landlord’s use of the Security Deposit shall not prevent Landlord from exercising any other remedy available to Landlord under this Lease, at law or in equity and shall not operate as either liquidated damages or as a
limitation on any recovery to which Landlord may otherwise be entitled. If any portion of the Security Deposit is used, applied, or retained by Landlord, Tenant shall, within ten (10) days after the written demand therefor, deposit cash with
Landlord in an amount sufficient to restore the Security Deposit to its original amount. Landlord shall return the Security Deposit or the balance thereof (as applicable) to Tenant within one (1) month after the later of the Expiration Date,
Tenant’s surrender of possession of the Premises to Landlord in the condition required under this Lease, and Tenant’s payment of all outstanding Rent. Upon the return of the Security Deposit or the balance thereof (as applicable) to
Tenant, Landlord shall be completely relieved of liability with respect to the Security Deposit. If the originally named Tenant has assigned this Lease, Landlord may return the Security Deposit or the balance thereof (as applicable) to the current
Tenant unless Landlord receives reasonably satisfactory evidence of the originally named Tenant’s right to receive the Security Deposit. If Landlord conveys ownership of the Building, Landlord shall deliver the Security Deposit to the
transferee, and (provided that such transferee assumes all of Landlord’s obligations under this Lease) Landlord shall thereupon be released from all liability for the return of such Security Deposit and Tenant shall look solely to the
transferee for the return of the Security Deposit. 
 (c) If Landlord does not receive the full payment from Tenant of any Rent when due
under this Lease (without regard to any notice and/or cure period to which Tenant might be entitled), Tenant shall also pay to Landlord as Additional Rent a late fee in the amount of five percent (5%) of such overdue amount. Notwithstanding the
foregoing, Landlord shall waive the above-referenced late fee two (2) times during any twelve (12) consecutive months of the Term provided Tenant makes the required payment within five (5) days after receipt of notice of such late
payment. With respect to any Rent payment (whether it be by check, ACH/wire, or other method) that is returned unpaid for any reason, Landlord shall have the right to assess a reasonable fee to Tenant as Additional Rent, which fee is currently
$40.00 per returned payment. 
 5. OPERATING EXPENSES. 

(a) Certain Definitions. 

(i) “Janitorial Expenses” means all reasonable costs associated with trash and garbage removal, recycling, cleaning, and
sanitizing the Building, and the items of work set forth in Exhibit D attached hereto. 

  
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 (ii) “Operating Expenses” means collectively Project Expenses and Taxes.

 (iii) “Project Expenses” means all reasonable costs and expenses paid, incurred, or accrued by Landlord in connection
with the maintenance, operation, repair, and replacement of the Project including, without limitation: a management fee not to exceed three percent (3%) of gross rents and revenues from the Project; all costs associated with the removal of snow
and ice from the Project; property management office rent; conference room and fitness center costs to the extent such amenities are made available to Tenant at no charge; transportation program costs, such as a shuttle made available to Tenant at
no charge; security measures; Janitorial Expenses; Project Utility Costs (as defined in Section 6 below); capital expenditures, repairs, and replacements, but only to the extent of the amortized costs of such capital item over the useful
life of the improvement, in accordance with generally accepted accounting principles, provided such capital items are: (I) incurred to comply with Laws that are amended, become effective, or are interpreted differently after the execution of
this Lease, or insurance or security requirements; (II) are intended to have cost-saving benefits over the Term of this Lease or reduce the rate of increase in Operating Expenses; or (III) is a reasonably prudent measure to improve the
safe operation of the Project, or improve or maintain the access to, quality, appearance or integrity of, the Building; all insurance premiums and deductibles paid or payable by Landlord with respect to the Project; and the cost of providing those
services required to be furnished by Landlord under this Lease. Notwithstanding the foregoing, “Project Expenses” shall not include any of the following: (A) repairs or other work occasioned by fire, windstorm, or other
insured casualty or by the exercise of the right of eminent domain to the extent Landlord actually receives insurance proceeds or condemnation awards therefor (or which would have been received had Landlord maintained the insurance required
hereunder); (B) leasing commissions, accountants’, consultants’, auditors or attorneys’ fees, costs and disbursements and other expenses incurred in connection with negotiations or disputes with other tenants or prospective
tenants or other occupants, or associated with the enforcement of any other leases or the defense of Landlord’s title to or interest in the real property or any part thereof; (C) costs incurred by Landlord in connection with the original
construction of the Building and related facilities; (D) costs (including permit, license, and inspection fees) incurred in renovating or otherwise improving or decorating, painting, or redecorating leased space for other tenants or other
occupants or vacant space; (E) interest on debt or amortization payments on any mortgage or deeds of trust or any other borrowings and any ground rent; (F) any compensation paid to clerks, attendants or other persons in commercial
concessions operated by Landlord; (G) any fines or fees for Landlord’s failure to comply with Laws; (H) legal, accounting, and other expenses related to Landlord’s financing, refinancing, mortgaging, or selling the Building or
the Project; (I) any increase in an insurance premium caused by the non-general office use, occupancy, or act of another tenant; (J) costs for sculpture, decorations, painting, or other objects of art in excess of amounts typically spent
for such items in office buildings of comparable quality in the competitive area of the Building; (K) cost of any political, charitable, or civic contribution or donation; (L) reserves for repairs, maintenance, and replacements;
(M) Taxes; (N) cost of utilities directly metered or submetered to Building tenants and paid separately by such tenants; (O) fines, interest, penalties, or liens arising by reason of Landlord’s failure to pay any Project Expenses
when due, except that Project Expenses shall include interest or similar charges if the collecting authority permits such Project Expenses to be paid in installments with interest thereon, such payments are not considered overdue by such

  
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authority and Landlord pays the Project Expenses in such installments; (P) costs and expenses associated with hazardous waste or hazardous substances not generated or brought to the Project
by Tenant or its agents including but not limited to the cleanup of such hazardous waste or hazardous substances and the costs of any litigation (including, but not limited to reasonable attorneys’ fees) arising out of the discovery of such
hazardous waste or hazardous substances; (Q) the portion of any wages, salaries, fees, or fringe benefits paid to personnel above the level of regional property manager; (R) costs of extraordinary services provided to other tenants of the
Building or services to which Tenant is not entitled (including, without limitation, costs specially billed to and paid by specific tenants); (S) all costs relating to activities for the solicitation and execution of leases of space in the
Building, including legal fees, real estate brokers’ commissions, expenses, fees, and advertising, moving expenses, design fees, rental concessions, rental credits, tenant improvement allowances, lease assumptions or any other cost and expenses
incurred in the connection with the leasing of any space in the Building; (T) costs representing an amount paid to an affiliate of Landlord (exclusive of any management fee permitted under the Operating Expense inclusions) to the extent in
excess of market rates for comparable services if rendered by unrelated third parties; (U) costs arising from Landlord’s default under this Lease or any other lease for space in the Building; (V) costs of selling the Project or any
portion thereof or interest therein; (W) costs or expenses arising from the gross negligence of Landlord or its agents or employees; (X) costs incurred to remedy, repair, or otherwise correct violations of Laws that exist on the
Commencement Date; (Y) ground rents or rentals payable by Landlord pursuant to any over-lease; (Z) repairs for which Landlord is covered by a manufacturer’s, materialman’s, vendor’s or contractor’s warranty;
(AA) ground lease payments; (BB) any administrative or management fees, except as otherwise set forth above; (CC) costs to maintain, repair or replace the Building structure; (DD) any expense that, pursuant to generally accepted
accounting principles, is not properly characterized as an “operating expense”; and (EE) costs incurred in operating, maintaining, or owning any conference center or fitness center in the Project that is not made available to Tenant
at no charge. 
 (iv) “Taxes” means all taxes, assessments, and other governmental charges, whether general or special,
ordinary or extraordinary, foreseen or unforeseen, including without limitation business improvement district charges, improvement contributions paid to business improvement districts or similar organizations, and special assessments for public
improvements or traffic districts, that are levied or assessed against, or with respect to the ownership of, all or any portion of the Project during the Term or, if levied or assessed prior to the Term, are properly allocable to the Term, business
property operating license charges, and real estate tax appeal expenditures incurred by Landlord. “Taxes” shall not include: (i) any inheritance, estate, succession, transfer, gift, franchise, corporation, net income or profit
tax or capital levy that is or may be imposed upon Landlord; or (ii) any transfer tax or recording charge resulting from a transfer of the Building or the Project; provided, however, if at any time during the Term the method of
taxation prevailing at the commencement of the Term shall be altered such that in lieu of or as a substitute in whole or in part for any Taxes now levied, assessed, or imposed on real estate there shall be levied, assessed, or imposed: (A) a
tax on the rents received from such real estate; or (B) a license fee measured by the rents receivable by Landlord from the Premises or any portion thereof; or (C) a tax or license fee imposed upon the Premises or any portion thereof, then
the same shall be included in Taxes. Tenant may not file or participate in any Tax appeals for any tax lot in the Project. Further, “Taxes” shall not include any sales, use, use and occupancy, transaction privilege, or other excise
tax that may at any time be levied or 

  
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imposed upon Tenant, or measured by any amount payable by Tenant under this Lease, whether such tax exists on the date of this Lease or is adopted hereafter (collectively, “Other
Taxes”), including without limitation the Philadelphia use and occupancy tax. Tenant shall pay all Other Taxes monthly or otherwise when due, whether collected by Landlord or collected directly by the applicable governmental agency; if
applicable Law requires Landlord to collect any Other Taxes, such Other Taxes shall be payable to Landlord as Additional Rent. 
 (v)
“Tenant’s Share” means the rentable square footage of the Premises divided by the rentable square footage of the Building on the date of calculation, which on the date of this Lease is stipulated to be 1.05%. 

(b) Commencing on the Commencement Date and continuing thereafter during the Term, Tenant shall pay to Landlord in advance on a monthly basis,
payable pursuant to Section 5(c) below, Tenant’s Share of Operating Expenses. If the Building is operated as part of a complex of buildings or in conjunction with other buildings or parcels of land, then Landlord may prorate the
common expenses and costs with respect to each such building or parcel of land in such manner as Landlord, in its sole but reasonable judgment, shall determine. Landlord shall calculate Operating Expenses using generally accepted accounting
principles, and may allocate certain categories of Operating Expenses to the applicable tenants on a commercially reasonable basis. For purposes of calculating Tenant’s Share of Controllable Project Expenses (as defined below), the total
Controllable Project Expenses for each year subsequent to the first full calendar year of the Term (“First Lease Year”) shall not exceed the applicable Cap Amount (as defined below) for the applicable subsequent calendar year. The
“Cap Amount” for each subsequent year shall be equal to the Controllable Project Expenses for the First Lease Year, increased on a compounded basis by five percent (5%) annually (that is, the Cap Amount for the first subsequent
year shall be equal to 1.05 multiplied by the First Lease Year Controllable Project Expenses, the Cap Amount for the second subsequent year shall be equal to (1.05 x 1.05) multiplied by the First Lease Year Controllable Project Expenses and so on,
throughout the Term). The cap on Controllable Project Expenses set forth herein shall also be calculated on a cumulative basis so that if in any year subsequent to the First Lease Year, the Controllable Project Expenses exceed the applicable Cap
Amount (“Deferred Amount”), the Deferred Amount(s) shall be carried over to the following year(s) and will be charged to Tenant in the following year(s) to the extent Controllable Project Expenses are less than the Cap Amount for
the year(s) in question. “Controllable Project Expenses” means all Project Expenses that are within the reasonable control of Landlord, such as landscaping and regular common area maintenance, but specifically excluding utility
costs, Taxes, snow and ice removal, insurance, costs resulting from a Force Majeure Event, wage increases due to collective bargaining agreements and/or increases in the minimum wage, management fees, and costs resulting from a change in Law
occurring after the date of this Lease. 
 (c) For each calendar year (or portion thereof) for which Tenant has an obligation to pay any
Operating Expenses, Landlord shall send to Tenant a statement of the monthly amount of projected Operating Expenses due from Tenant for such calendar year (“Estimated Operating’ Expenses”), and Tenant shall pay to Landlord such
monthly amount of Estimated Operating Expenses as provided in Section 5(b). without further notice, demand, setoff, deduction, or counterclaim (except as otherwise provided herein). As soon as administratively available after each
calendar year (but in any event Landlord shall use 

  
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commercially reasonable efforts to provide such statement within 180 days after each calendar year), Landlord shall send to Tenant a reconciliation statement of the actual Operating Expenses for
the prior calendar year including Tenant’s Share thereof and an itemized list of costs (“Reconciliation Statement”). If the amount actually paid by Tenant as Estimated Operating Expenses exceeds the amount due per the
Reconciliation Statement, Tenant shall receive a credit in an amount equal to the overpayment, which credit shall be applied towards future Rent until fully credited. If the credit exceeds the aggregate future Rent owed by Tenant (or if the Term has
expired), and there is no Event of Default, Landlord shall pay the excess amount to Tenant within thirty (30) days after delivery of the Reconciliation Statement. If Landlord has undercharged Tenant, then Landlord shall either send Tenant an
invoice setting forth the additional amount due or indicate the amount due as part of the Reconciliation Statement, which amount shall be paid in full by Tenant within thirty (30) days after receipt of such invoice. Notwithstanding the
foregoing, if Landlord fails to provide a Reconciliation Statement for any final expense within two (2) years after such expense was incurred and billed to Landlord, Landlord shall be deemed to have waived its right to collect any underpayments
by Tenant of such amounts. 
 (d) If, during the Term, less than ninety-five percent (95%) of the rentable area of the Building is or
was occupied by tenants, Project Expenses shall be deemed for such year to be an amount equal to the costs that would have been incurred had the occupancy of the Building been at least ninety-five percent (95%) throughout such year, as
reasonably determined by Landlord and taking into account that certain expenses fluctuate with the Building’s occupancy level (e.g., Janitorial Expenses) and certain expenses do not so fluctuate (e.g., landscaping). In addition, if Landlord is
not obligated or otherwise does not offer to furnish an item or a service to a particular tenant or portion of the Building (e.g., if a tenant separately contracts with an office cleaning firm to clean such tenant’s premises) and the cost of
such item or service would otherwise be included in Project Expenses, Landlord shall equitably adjust the Project Expenses so the cost of the item or service is shared only by tenants actually receiving such item or service. All payment calculations
under this Section shall be prorated for any partial calendar years during the Term and all calculations shall be based upon Project Expenses as grossed-up in accordance with the terms of this Lease. Tenant’s obligations under this Section
shall survive the Expiration Date. 
 (e) If Landlord or any affiliate of Landlord has elected to qualify as a real estate investment trust
(“REIT”), any service required or permitted to be performed by Landlord pursuant to this Lease, the charge or cost of which may be treated as impermissible tenant service income under the laws governing a REIT, may be performed by
an independent contractor of Landlord, Landlord’s property manager, or a taxable REIT subsidiary that is affiliated with either Landlord or Landlord’s property manager (each, a “Service Provider”), so long as the rates
charged by the Service Provider are substantially similar to other independent contractors’ rates charged in the Philadelphia, Pennsylvania area. If Tenant is subject to a charge under this Lease for any such service, then at Landlord’s
direction Tenant shall pay the charge for such service either to Landlord for further payment to the Service Provider or directly to the Service Provider and, in either case: (a) Landlord shall credit such payment against any charge for such
service made by Landlord to Tenant under this Lease; and (b) Tenant’s payment of the Service Provider shall not relieve Landlord from any obligation under this Lease concerning the provisions of such services. 

  
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 (f) Provided there is no outstanding monetary default by Tenant under this Lease (that
continues beyond the expiration of all applicable notice and/or cure periods), Tenant shall have the right, at its sole cost and expense, to cause Landlord’s records related to a Reconciliation Statement to be audited provided: (i) Tenant
provides notice of its intent to audit such Reconciliation Statement within four (4) months after receipt of the Reconciliation Statement; (ii) the audit is performed by Tenant’s accountant or a certified public accountant that has
not been retained on a contingency basis or other basis where its compensation relates to the cost savings of Tenant; (iii) any such audit may not occur more frequently than once during each twelve (12)-month period of the Term, nor apply
to any year prior to the year of the then-current Reconciliation Statement being reviewed; (iv) the audit is completed within two (2) months after the date that Landlord makes all of the necessary and applicable records available to Tenant
or Tenant’s auditor; (v) the contents of Landlord’s records shall be kept confidential by Tenant, its auditor, and its other professional advisors, other than as required by applicable Law, or in connection with any litigation or
other proceeding arising in connection with this Lease, and if requested by Landlord, Tenant and its auditor shall execute Landlord’s standard confidentiality agreement (which shall be in a form reasonably acceptable to Tenant) as a condition
to Tenant’s audit rights under this paragraph; and (vi) if Tenant’s accountant or Tenant’s auditor determines that an overpayment is due Tenant, Tenant’s auditor shall produce a detailed report addressed to both Landlord and
Tenant, which report shall be delivered within thirty (30) days after Tenant’s auditor’s completion of the audit. During completion of Tenant’s audit, Tenant shall nonetheless timely pay all of Tenant’s Share of Operating
Expenses without setoff or deduction. If Tenant’s audit report discloses any discrepancy, Landlord and Tenant shall use good faith efforts to resolve the dispute. If the parties are unable to reach agreement within twenty (20) days after
Landlord’s receipt of the audit report, Tenant shall have the right to refer the matter to a mutually acceptable independent certified public accountant, who shall work in good faith with Landlord and Tenant to resolve the discrepancy;
provided if Tenant does not do so within ten (10) days after the expiration of such twenty (20)-day period, Landlord’s calculations and the Reconciliation Statement at issue shall be deemed final and accepted by Tenant. The
fees and costs of such independent accountant to which such dispute is referred shall be borne by the unsuccessful party and shall be shared pro rata to the extent each party is unsuccessful as determined by such independent certified public
accountant, whose decision shall be final and binding. Within thirty (30) days after resolution of the dispute, whether by agreement of the parties or a final decision of an independent accountant, Landlord shall pay or credit to Tenant, or
Tenant shall pay to Landlord, as the case may be, all unpaid Operating Expenses due and owing. Notwithstanding anything to the contrary contained herein, in the event, by agreement or as a result of the findings of such independent accountant or as
a result of a final judicial determination, it is determined that the actual Operating Expenses exceeded those claimed by Landlord by more than five percent (5%), then Landlord shall reimburse Tenant within thirty (30) days after receipt
of an invoice with reasonable supporting documentation for the reasonable, third-party costs of Tenant’s audit, not to exceed $2,500. 

6. UTILITIES. 
 (a) Commencing on
the Commencement Date, and continuing throughout the Term, Tenant shall pay for utility services as follows without setoff, deduction, or counterclaim (except as otherwise provided herein): (i) Tenant shall pay directly to the applicable
utility service provider for any utilities that are separately metered (not submetered) to the Premises; 

  
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(ii) Tenant shall pay Landlord for any utilities serving the Premises that are separately submetered based upon Tenant’s submetered usage; and (iii) Tenant shall pay Landlord for
Tenant’s Share of Project Utility Costs, as set forth in Section 5 above. “Project Utility Costs” means the total cost for all utilities serving the Project, excluding the costs of utilities that are directly
metered or submetered to Building tenants or paid separately by such tenants. Notwithstanding anything to the contrary in this Lease, Landlord shall have the right, upon reasonable advance written notice to Tenant, to install meters, submeters, or
other energy-reducing systems in the Premises at any time to measure any or all utilities serving the Premises, at no cost to Tenant. In exercising such right, Landlord shall use its commercially reasonable efforts to avoid interfering with
Tenant’s use and occupancy of the Premises. For those utilities set forth in subsection (ii) above, Landlord shall invoice Tenant for such utilities as Additional Rent (payable within thirty (30) days after receipt of an invoice
therefor). For those utilities set forth in subsection (ii) above, Landlord shall have the right to either invoice Tenant for such utilities as Additional Rent (payable within thirty (30) days after receipt of an invoice therefor), or
together with Operating Expenses. Landlord shall have the right to estimate the utility charge, which estimated amount shall be payable to Landlord within thirty (30) days after receipt of an invoice therefor and may be included along with the
invoice for Project Expenses, provided Landlord shall be required to reconcile on an annual basis based on utility invoices received for such period. The cost of utilities payable by Tenant under this Section shall include all applicable
taxes and Landlord’s then-current reasonable charges for reading the applicable meters, provided Landlord shall have the right to engage a third party to read the submeters, and Tenant shall reimburse Landlord for both the utilities consumed as
evidenced by the meters plus the reasonable costs for reading the meters within thirty (30) days after receipt of an invoice therefor. Tenant shall pay such rates as Landlord may establish from time to time, which shall not be in excess of any
applicable rates chargeable by Law, or in excess of the general service rate or other such rate that would apply to Tenant’s consumption if charged by the utility or municipality serving the Building or general area in which the Building is
located. If Tenant fails to pay timely any direct-metered utility charges from the applicable utility provider, Landlord shall have the right but not the obligation to pay such charges on Tenant’s behalf and bill Tenant for such costs plus the
Administrative Fee (as defined in Section 17), which amount shall be payable to Landlord as Additional Rent within thirty (30) days after receipt of an invoice therefor. Tenant shall at all times comply with the rules, regulations,
terms, policies, and conditions applicable to the service, equipment, wiring, and requirements of the utility supplying electricity to the Building. 

(b) For any separately metered utilities, Landlord is hereby authorized to request and obtain, on behalf of Tenant, Tenant’s utility
consumption data from the applicable utility provider for informational purposes and to enable Landlord to obtain full building Energy Star scoring for the Building. Landlord shall have the right, upon reasonable advance written notice to Tenant
(except in the case of an emergency) to shut down the Building systems (including electricity and HVAC systems) for required maintenance, safety inspections, any other commercially acceptable reason, including without limitation in cases of
emergency. In exercising such right, Landlord shall use its commercially reasonable efforts to avoid materially interfering with Tenant’s use and occupancy of the Premises. Landlord shall not be liable for any interruption in providing any
utility that Landlord is obligated to provide under this Lease, unless such interruption or delay: (i) renders the Premises or any material portion thereof untenantable for the normal conduct of Tenant’s business at the Premises, and
Tenant has ceased 

  
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using such untenantable portion, provided Tenant shall first endeavor to use any generator that serves the Premises or of which Tenant has the beneficial use; (ii) results from
Landlord’s negligence or willful misconduct; and (iii) extends for a period longer than five (5) consecutive days, in which case, Tenant’s obligation to pay Rent shall be abated with respect to the untenantable portion of the
Premises that Tenant has ceased using for the period beginning on the 6th consecutive day after such conditions are met and ending on the earlier of: (A) the date Tenant recommences using the
Premises or the applicable portion thereof; or (B) the date on which the service(s) is substantially restored. The rental abatement described above shall be Tenant’s sole remedy in the event of a utility interruption, and Tenant hereby
waives any other rights against Landlord in connection therewith. Landlord shall have the right to change the utility providers to the Project at any time, and all providers selected by Landlord must provide service at competitive market prices. In
the event of a casualty or condemnation affecting the Building and/or the Premises, the terms of Sections 14 and 15, respectively, shall control over the provisions of this Section. 

(c) If Landlord reasonably determines that: (i) Tenant exceeds the design conditions for the heating, ventilation, and air conditioning
(“HVAC”) system serving the Premises, introduces into the Premises equipment that overloads such system, or causes such system to not adequately perform its proper functions; or (ii) the heavy concentration of personnel,
motors, machines, or equipment used in the Premises, including telephone and computer equipment, or any other condition in the Premises caused by Tenant (for example, more than one shift per day or twenty-four (24)-hour use of the Premises),
adversely affects the temperature or humidity otherwise maintained by such system, then Landlord shall notify Tenant in writing and Tenant shall have thirty (30) days to remedy the situation to Landlord’s reasonable satisfaction (or such
longer period as is reasonably required to remedy the situation provided Tenant promptly commences and diligently continues to effectuate a remedy). If Tenant fails to timely remedy the situation to Landlord’s reasonable satisfaction, Landlord
shall have the right to install one or more supplemental air conditioning units in the Premises with the reasonable cost thereof, including the cost of installation, operation and maintenance, being payable by Tenant to Landlord within
thirty (30) days after Landlord’s written demand. Tenant shall not change or adjust any closed or sealed thermostat or other element of the HVAC system serving the Premises without Landlord’s express prior written consent, which
consent shall not be unreasonably withheld, conditioned or delayed. Landlord may install and operate meters or any other reasonable system for monitoring or estimating any services or utilities used by Tenant in excess of those required to be
provided by Landlord (including a system for Landlord’s engineer reasonably to estimate any such excess usage). If such system indicates such excess services or utilities, Tenant shall pay Landlord’s reasonable charges for installing and
operating such system and any supplementary air conditioning, ventilation, heat, electrical, or other systems or equipment (or adjustments or modifications to the existing Building systems and equipment), and Landlord’s reasonable charges for
such amount of excess services or utilities used by Tenant. All Tenant’s Supplemental HVAC (as defined in Section 11(a) below) shall be separately metered to the Premises at Tenant’s cost, and Tenant shall be solely responsible
for all electricity registered by, and the maintenance and replacement of, such meters. Landlord has no obligation to keep cool any of Tenant’s information technology equipment that is placed together in one room, on a rack, or in any similar
manner (“IT Equipment”), and Tenant waives any claim against Landlord in connection with Tenant’s IT Equipment. Landlord shall have the option to require that the computer room and/or information technology closet in the
Premises shall be 

  
 11 

 
separately submetered at Tenant’s expense, and Tenant shall pay Landlord for all electricity registered in such submeter. Within one (1) month after written request, Tenant shall
provide to Landlord electrical load information reasonably requested by Landlord with respect to any computer room and/or information technology closet in the Premises. 

7. LANDLORD SERVICES. 

(a) Subject to Section 5 and Section 6, Landlord shall provide the following to the Premises during the Term:
(i) HVAC service in the respective seasons during Business Hours; provided HVAC service to the Premises on Saturdays will be provided only upon Tenant’s prior request to Landlord received no later than noon on the preceding business day;
(ii) electricity for lighting and standard office equipment for comparable buildings in the market in which the Project is located; (iii) water, sewer, and, to the extent applicable to the Building, gas, oil, and steam service; and
(iv) cleaning services meeting the minimum specifications set forth in Exhibit D attached hereto. Tenant, at Tenant’s expense, shall make arrangements with the applicable utility companies and public bodies to provide, in
Tenant’s name, telephone, cable, and any other utility service not provided by Landlord that Tenant desires at the Premises. 
 (b)
Landlord shall not be obligated to furnish any services, supplies, or utilities other than as set forth in this Lease; provided, however, upon Tenant’s prior request sent in accordance with Section 25(p) below,
Landlord may furnish additional services, supplies, or utilities, in which case Tenant shall pay to Landlord, within thirty (30) days after demand, Landlord’s then-current actual charge for such additional services, supplies, or utilities,
or Tenant’s pro rata share thereof, if applicable, as reasonably determined by Landlord. Landlord’s current rate for HVAC service outside of Business Hours requested with at least twenty (24) hours’ prior notice (or by
noon for weekend service) is $10.00 per hour, per zone, with a two (2)-hour minimum if the service does not commence immediately following the end of a day’s Business Hours. 

8. USE: SIGNS: COMMON AREAS. 

(a) Tenant shall use the Premises for general office use (non-medical) befitting a class A office building and storage incidental thereto, and
for no other purpose (“Permitted Use”). Tenant’s use of the Premises for the Permitted Use shall be subject to all applicable Laws, and to all reasonable requirements of the insurers of the Building. Tenant represents and
warrants to Landlord, for informational purposes only, that Tenant’s current NAICS Code is set forth in Section 1 hereof, provided the foregoing shall not be construed in any manner as a restriction on the Permitted Use. Landlord
represents and warrants to Tenant to its actual knowledge without independent investigation or inquiry, as of the date of this Lease that Tenant’s use of the Premises for the Permitted Use does not violate any restrictions under any leases or
agreements applicable to the Project. 
 (b) Landlord shall provide Tenant with: (i) Building-standard identification signage at the
main entrance to the Premises, the costs of which shall be paid for by Landlord; and (ii) Building-standard directional signage in the multi-tenant elevator lobby on the 6th floor of the
Building, the costs of which shall be paid for by Landlord for the originally named Tenant, otherwise by Tenant as Additional Rent within ten (10) days after written demand. Tenant shall not place, erect, or maintain any signs at the Premises,
the Building, or the Project that are visible from outside of the Premises. 

  
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 (c) Subject to the Building rules and regulations set forth on Exhibit E
attached hereto (as the same may be modified pursuant to Section 19 herein), Tenant shall have the nonexclusive right in common with others to use the Common Areas for their intended purposes. 

(d) Landlord shall have the right in its sole discretion to, from time to time, construct, maintain, operate, repair, close, limit, take out of
service, alter, change, and modify all or any part of the Common Areas, provided, however, in no event shall the Common Areas be altered in such a way that will materially and negatively affect Tenant’s visibility, ingress/egress
and/or use and occupancy of the Premises. Landlord, Landlord’s agents, approved contractors, and utility service providers shall have the right to install, use, and maintain ducts, pipes, wiring, and conduits in and through the Premises
provided Landlord avoids material interference to the conduct of Tenant’s business operations in the Premises and such use does not cause the usable area of the Premises to be reduced beyond a de minimis amount. 

(e) Subject to Landlord’s reasonable security measures and Force Majeure Events (as defined in Section 25(g)), Landlord shall
provide Tenant with access to the Building and, if applicable, passenger elevator service for use in common with others for access to and from the Premises twenty (24) hours per day, seven (7) days per week, except during emergencies.
Landlord shall have the right to limit the number of elevators (if any) to be operated during repairs and during non-Business Hours and on weekends. If applicable, Landlord shall provide Tenant with access to the freight elevator(s) of the Building
from time to time following receipt of Tenant’s prior request, and Tenant shall pay Landlord’s then-current charge for use of such freight elevators. 

9. TENANT’S ALTERATIONS. 

(a) Except as otherwise set forth herein, Tenant shall not, and shall not permit any Tenant Agent to, cut, drill into, or secure any fixture,
apparatus, or equipment, or make alterations, improvements, or physical additions of any kind to any part of the Premises (collectively, “Alterations”) without first obtaining the written consent of Landlord, which consent shall not
be unreasonably withheld, conditioned, or delayed. “Tenant Agent” means any agent, employee, subtenant, assignee, contractor, client, family member, licensee, customer, invitee, or guest of Tenant. All Alterations shall be completed
in compliance with all applicable Laws, and Landlord’s reasonable rules and regulations for construction, and sustainable guidelines and procedures, using new or comparable materials only, by a contractor reasonably approved in writing by
Landlord, and on days and at times reasonably approved in writing by Landlord. Notwithstanding the foregoing, Landlord’s consent shall not be required for any Alteration costing less than $25,000.00 and that: (i) is interior and
nonstructural; (ii) does not impact any of the Building systems, involve electrical or drywall work, require a building permit, materially affect the air quality in the Building, or require Landlord to incur additional costs as a result
thereof; and (iii) is not visible from outside of the Premises. 

  
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 (b) Throughout the performance of Alterations, Tenant shall carry, or cause any contractor,
subcontractor, or design professional to carry, via written contract, workers’ compensation insurance in statutory limits together with employer’s liability insurance, commercial general liability insurance, automobile liability, and
umbrella/excess liability insurance in like form and limits in accordance with the terms and conditions required of Tenant under Section 12 below, and such other insurance coverage and limits as Landlord may otherwise reasonably require,
which may include, without limitation, reasonable amounts of professional liability insurance with respect to design professionals, as well as contractor’s pollution liability with respect to contractors and subcontractors. Tenant shall also
require any such contractor, subcontractor, or design professional to satisfy the same additional coverage terms as required of Tenant under Section 12 below with respect to naming each Additional Insured (as defined in
Section 12) as an additional insured by way of endorsement ISO CG 20 37 together with CG 20 10 or their equivalent, which insurance shall be primary, and any other insurance that may be available to Landlord and any such additional
insured will be excess and noncontributory, and waiving all rights of recovery and subrogation. In addition, Tenant shall carry “all risk” Builder’s Risk insurance covering the Alterations, unless otherwise agreed upon in writing by
Landlord and Tenant. Tenant shall provide to Landlord prior written notice of its intention to perform any Alteration, together with a certificate of insurance from each contractor and design professional evidencing that the insurance required under
this Lease is in effect during all construction activities. 
 (c) Except to the extent included in the Leasehold Improvements, Tenant shall
be solely responsible for the installation and maintenance of its data, telecommunication, and security systems and wiring at the Premises, which shall be done in compliance with all applicable Laws, and Landlord’s reasonable rules and
regulations. Upon Landlord’s request, Tenant shall provide Landlord with a release of liens from all contractors, subcontractors, and design professionals associated with all Alterations. Tenant shall be responsible for all elements of
Alterations (including, without limitation, compliance with Laws, and functionality of the design), and Landlord’s approval of any Alteration and the plans therefor shall in no event relieve Tenant of the responsibility for such design, or
create responsibility or liability on Landlord’s part for their completeness, design sufficiency, or compliance with Laws. With respect to all improvements and Alterations made after the date hereof, Tenant acknowledges that: (A) Tenant is
not, under any circumstance, acting as the agent of Landlord; (B) Landlord did not cause or request such Alterations to be made; (C) Landlord has not ratified such work; and (D) Landlord did not authorize such Alterations within the
meaning of applicable State statutes. Nothing in this Lease or in any consent to the making of Alterations or improvements shall be deemed or construed in any way as constituting a request by Landlord, express or implied, to any contractor,
subcontractor, or supplier for the performance of any labor or the furnishing of any materials for the use or benefit of Landlord. Tenant shall not overload any floor or part thereof in the Premises or the Building, including any public corridors or
elevators, by bringing in, placing, storing, installing or removing any large or heavy articles, and Landlord may prohibit, or may direct and control the location and size of, safes and all other heavy articles, and may require, at Tenant’s
sole cost and expense, supplementary supports of such material and dimensions as Landlord may deem reasonably necessary to properly distribute the weight. 

  
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 10. ASSIGNMENT AND SUBLETTING. 

(a) Except as expressly permitted pursuant to Section 10(c), neither Tenant nor Tenant’s legal representatives or
successors-in-interest by operation of law or otherwise, shall sell, assign, transfer, hypothecate, mortgage, encumber, grant concessions or licenses, sublet, or otherwise dispose of all or any interest in this Lease or the Premises, or permit any
person or entity other than Tenant to occupy any portion of the Premises (each of the foregoing is a “Transfer” to a “Transferee”), without Landlord’s prior written consent, which consent shall not be
unreasonably withheld, conditioned, or delayed. Any Transfer undertaken without Landlord’s prior written consent (other than pursuant to Section 10(c)) shall constitute an Event of Default and shall, at Landlord’s option, be
void and/or terminate this Lease. For purposes of this Lease, a Transfer shall include, without limitation, any assignment by operation of law, and any merger, consolidation, or asset sale involving Tenant. Consent by Landlord to any one Transfer
shall be held to apply only to the specific Transfer authorized, and shall not be construed as a waiver of the duty of Tenant, or Tenant’s legal representatives or assigns, to obtain from Landlord consent to any other or subsequent Transfers
pursuant to the foregoing, or as modifying or limiting the rights of Landlord under the foregoing covenant by Tenant. 
 (b) Without limiting
the bases upon which Landlord may reasonably withhold its consent to a proposed Transfer, it shall not be unreasonable for Landlord to withhold its consent if: (i) the proposed Transferee shall have a net worth that is not acceptable to
Landlord in Landlord’s reasonable discretion, taking into account the remaining obligations under this Lease and the fact that Tenant is not released; (ii) the proposed Transferee, in Landlord’s reasonable opinion, is not reputable
and of good character; (iii) the portion of the Premises requested to be subleased renders the balance of the Premises unleasable as a separate area; (iv) Tenant is proposing a sublease at a rental or sub-rental rate that is less than the
then-fair market rental rate for the portion of the Premises being subleased; (v) Tenant is proposing to Transfer to an existing tenant of the Building or another property owned by Landlord or Landlord’s affiliate(s) (and Landlord and/or
Landlord’s affiliate(s), as applicable, then has comparable space in the Building and/or other property, as applicable, available for lease), or to another prospect with whom Landlord or Landlord’s affiliate(s) are then negotiating in the
market of which the Building is a part; or (vi) the nature of such Transferee’s proposed business operation would or might reasonably violate the terms of this Lease or of any other lease for the Building (including any exclusivity
provisions), or would, in Landlord’s reasonable judgment, otherwise be incompatible with other tenancies in the Building. 
 (c)
Notwithstanding anything to the contrary in this Lease, Tenant shall have the right without the prior consent of Landlord, but after prior written notice to Landlord, to make a Transfer to any Affiliate (as defined below), or an entity into which
Tenant merges or that acquires substantially all of the assets or stock or ownership interests of Tenant (“Surviving Entity”) (the Surviving Entity or Affiliate are also referred to as a “Permitted Transferee”);
provided: (i) Tenant delivers to Landlord the Transfer Information (as defined below); (ii) the Surviving Entity shall have a tangible net worth at least equal to the net worth of Tenant on the date of this Lease or otherwise reasonably
acceptable to Landlord taking into account the fact that the originally named Tenant is not being released; (iii) the originally named Tenant shall not be released or discharged from any liability under this Lease by reason of such Transfer,
and the Permitted Transferee shall assume in writing all of the obligations and liabilities of Tenant under this Lease; (iv) the use of the Premises shall not change, and the Permitted Transferee, in Landlord’s reasonable opinion, shall be
reputable and of good character befitting a class A office 

  
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building; and (v) such Transfer is for a good business purpose and not principally for the purpose of transferring the leasehold estate created by this Lease. An “Affiliate”
means a corporation, limited liability company, partnership, or other registered entity, fifty percent (50%) or more of whose equity interest is owned by the same persons or entities owning fifty percent (50%) or more of Tenant’s
equity interests, a subsidiary, or a parent corporation. 
 (d) If at any time during the Term Tenant desires to complete a Transfer that
requires Landlord’s consent, Tenant shall give written notice to Landlord of such desire together with the Transfer Information. If Tenant desires to sublease less than the entire Premises other than to pursuant to Section 10(c),
Landlord shall have the right to accelerate the Expiration Date with respect to (that is, recapture) the portion of the Premises that Tenant proposes to sublease. If Landlord elects to accelerate the Expiration Date pursuant to this paragraph,
Tenant shall have the right to rescind its request for Landlord’s consent to the proposed assignment or sublease by giving written notice of such rescission to Landlord within ten (10) business days after Tenant’s receipt of
Landlord’s acceleration election notice, in which case this Lease shall continue in full force and effect as if Landlord had not exercised such acceleration right. If Tenant does not so rescind its request: (A) Tenant shall deliver the
applicable portion thereof to Landlord in the same condition as Tenant is, by the terms of this Lease, required to deliver the Premises to Landlord upon the Expiration Date; and (B) Fixed Rent and Tenant’s Share shall be reduced on a per
rentable square foot basis for the area of the Premises that Tenant no longer leases. If Landlord elects to accelerate the Expiration Date for less than the entire Premises, the cost of erecting any demising walls, entrances, and entrance corridors,
and any other improvements required in connection therewith shall be performed by Landlord, with the cost thereof being divided evenly between Landlord and Tenant. 

(e) The “Transfer Information” means the following information: (i) a copy of the fully executed assignment and
assumption agreement, or sublease agreement, as applicable (with respect to a Permitted Transfer, such agreement to be delivered to Landlord within ten (10) business days after the transaction closes and with respect to all other Transfers,
such agreement shall be provided in draft form and shall not be executed until Landlord’s consent has been given); (ii) a copy of the then-current financials of the Transferee (either audited or certified by the chief financial officer of
the Transferee); and (iii) such other reasonably requested information by Landlord needed to confirm or determine Tenant’s compliance with the terms and conditions of this Section. 

(f) Fifty percent (50%) of any sums or other economic consideration received by Tenant as a result of any Transfer which requires
Landlord’s consent (except rental or other payments received that are attributable to the amortization of the cost of leasehold improvements made to the transferred portion of the Premises by Tenant for the Transferee, and other reasonable
expenses incident to the Transfer, including standard leasing commissions) whether denominated rentals under the sublease or otherwise, that exceed, in the aggregate, the total sums which Tenant is obligated to pay Landlord under this Lease
(prorated to reflect obligations allocable to that portion of the Premises subject to such Transfer) shall, at Landlord’s option, either be retained by Tenant or paid to Landlord, with Landlord’s portion being payable to Landlord as
Additional Rent without affecting or reducing any other obligation of Tenant hereunder. 

  
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 (g) Regardless of Landlord’s consent to a proposed Transfer, no Transfer shall release
Tenant from Tenant’s obligations or alter Tenant’s primary liability to fully and timely pay all Rent when due from time to time under this Lease and to fully and timely perform all of Tenant’s other obligations under this Lease, and
the originally named Tenant and all assignees shall be jointly and severally liable for all Tenant obligations under this Lease. The acceptance of rental by Landlord from any other person shall not be deemed to be a waiver by Landlord of any
provision hereof. If a Transferee defaults in the performance of any of the terms of this Lease, Landlord may proceed directly against the originally named Tenant without the necessity of exhausting remedies against such Transferee. If there has
been a Transfer and an Event of Default occurs, Landlord may collect Rent from the Transferee and apply the net amount collected to the Rent herein reserved; but no such collection shall be deemed a waiver of the provisions of this Section, an
acceptance of such Transferee as tenant hereunder or a release of Tenant from further performance of the covenants herein contained. 
 11.
REPAIRS AND MAINTENANCE. 
 (a) Except with respect to Landlord Repairs (as defined below), Tenant, at Tenant’s expense, shall
keep and maintain the interior, nonstructural portions of the Premises in good order and condition including promptly making all repairs necessary to keep and maintain such in good order and condition (other than ordinary wear and tear, provided
“ordinary wear and tear” does not, and shall not be deemed to, include any damage or deterioration that could have been prevented through proper maintenance, or by Tenant’s full and timely performance of its obligations under this
Lease) (except to the extent such maintenance, repair or replacement is required as a result of the negligence of Landlord or Landlord’s contractors, employees or agents, in which event it shall be the obligation of Landlord to maintain, repair
and/or replace same). When used in this Lease, “repairs” shall include repairs and any reasonably necessary replacements. For purposes of this Section, “nonstructural portions of the Premises” shall be deemed to exclude, without
limitation, all plumbing, electric and HVAC systems, whether located in or outside of the Premises (except for the Tenant’s Supplemental HVAC and Premises Hot Water Heaters). Tenant shall have the option of replacing lights, ballasts, tubes,
ceiling tiles, outlets and similar equipment itself or advising Landlord of Tenant’s desire to have Landlord make such repairs, in which case Tenant shall pay to Landlord for such repairs at Landlord’s then-standard rate (such rate to be
competitive with the market rate for such services). To the extent that Tenant requests that Landlord make any other repairs that are Tenant’s obligation to make under this Lease, Landlord may elect to make such repairs on Tenant’s behalf,
at Tenant’s reasonable expense, and Tenant shall pay to Landlord such expense along with the Administrative Fee. All Tenant repairs shall comply with Laws and utilize materials and equipment that are at least equal in quality, number, and
usefulness to those originally used in constructing the Building and the Premises. In addition, Tenant shall maintain, at Tenant’s expense, Tenant’s Supplemental HVAC, and/or Alterations in a clean and safe manner and in proper operating
condition throughout the Term. “Tenant’s Supplemental HVAC” means any supplemental HVAC system serving exclusively the Premises and installed by or on behalf of Tenant after the Commencement Date. “Premises Hot Water
Heater” means any hot water heater serving exclusively the Premises, including without limitation expansion tanks and any associated piping, but excluding the under-sink water heater existing on the date of this Lease. Tenant shall maintain
Tenant’s Supplemental HVAC under a service contract with a firm and upon such terms as may be reasonably satisfactory to Landlord, including inspection and 

  
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maintenance on at least a semiannual basis, and provide Landlord with a copy thereof. Within five (5) days after Landlord’s request, Tenant shall provide Landlord with evidence that
such contract is in place. All repairs to the Building and/or the Project made necessary by reason of the installation, maintenance, and operation of Tenant’s Supplemental HVAC, Premises Hot Water Heaters, and Alterations shall be Tenant’s
expense. In the event of an emergency, such as a burst waterline or act of God, Landlord shall have the right to make repairs for which Tenant is responsible hereunder (at Tenant’s reasonable cost) without giving Tenant prior notice, but in
such case Landlord shall provide notice to Tenant as soon as practicable thereafter, and Landlord shall take commercially reasonable steps to minimize the costs incurred. Further, Landlord shall have the right to make repairs for which Tenant is
responsible hereunder (at Tenant’s reasonable cost) with prior notice to Tenant if Landlord believes in its sole and absolute discretion that the repairs are necessary to prevent harm or damage to the Building, and Landlord shall take
commercially reasonable steps to minimize the costs incurred. 
 (b) Landlord, at Landlord’s expense (except to the extent such expenses
are includable in Project Expenses), shall make all necessary repairs to: (i) the footings and foundations and the structural elements of the Building; (ii) the roof of the Building; (iii) the HVAC, plumbing, elevators (if any),
electric, fire protection, fire alert and other utility systems servicing the Building and the Premises, but specifically excluding Tenant’s Supplemental HVAC, Premises Hot Water Heaters, Alterations, and any systems servicing exclusively the
Premises; (iv) the Building exterior; and (v) the Common Areas (collectively, “Landlord Repairs”). Any provision of this Lease to the contrary notwithstanding, any repairs to the Project or any portion thereof made
necessary by the negligent or willful act or omission of, or default under this Lease by, Tenant or any Tenant Agent shall be made at Tenant’s expense, subject to the waivers set forth in Section 12(g). 

(c) The parties agree it is in their mutual best interest that the Building and Premises be operated and maintained in a manner that is
environmentally responsible, fiscally prudent, and provides a safe and productive work environment. Accordingly, Tenant shall use commercially reasonable efforts, at no additional material cost to Tenant, to conduct its operations in the Building
and within the Premises to: (1) minimize to the extent reasonably feasible: (i) direct and indirect energy consumption and greenhouse gas emissions; (ii) water consumption; (iii) the amount of material entering the waste stream;
and (iv) negative impacts upon the indoor air quality of the Building; and (2) permit the Building to maintain its LEED rating and an Energy Star label, to the extent applicable. Landlord shall use commercially reasonable efforts to
operate and maintain the Common Areas of the Building to: (1) minimize to the extent reasonably feasible: (i) direct and indirect energy consumption and greenhouse gas emissions; (ii) water consumption; (iii) the amount of
material entering the waste stream; and (iv) negative impacts upon the indoor air quality of the Building; and (2) permit the Building to maintain its LEED rating and an Energy Star label, to the extent applicable, the costs of which shall
be included in Project Expenses (except to the extent otherwise not permitted). 
 12. INSURANCE: SUBROGATION RIGHTS. 

(a) Tenant shall not violate, or permit the violation of, any condition imposed by any insurance policy then issued in respect of the Project
and shall not do, or permit anything to be done, or keep or permit anything to be kept in the Premises, that would subject Landlord to 

  
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any liability or responsibility for personal injury or death or property damage, increase any insurance rate in respect of the Project over the rate that would otherwise then be in effect, result
in insurance companies of good standing refusing to insure the Project in amounts reasonably satisfactory to Landlord, or result in the cancellation of, or the assertion of any defense by the insurer in whole or in part to claims under, any policy
of insurance in respect of the Project. If, by reason of any failure of Tenant to comply with this Lease, the premiums on Landlord’s insurance on the Project are higher than they otherwise would be, Tenant shall reimburse Landlord, on demand,
for that part of such premiums attributable to such failure on the part of Tenant. Landlord hereby acknowledges and agrees that Tenant’s use of the Premises for the Permitted Use will not cause an increase in Landlord’s insurance premiums.

 (b) Tenant, at Tenant’s expense, shall obtain and keep in full force and effect at all times as of the Commencement Date (or
Tenant’s earlier accessing of the Premises), all of the following insurance policies: 
 (i) commercial general liability insurance
written on an ISO CG 00 01 occurrence policy form or its equivalent, including a Separation of Insureds clause, coverage for contractual liability covering Tenant’s contractual obligations under this Lease as ah insured contract, personal
injury liability, host liquor liability, premises-operations and hazards thereto, as well as liability arising out of this Lease in respect of the Premises and the conduct or operation of business therein. The minimum limits of coverage shall be no
less than $1,000,000 per occurrence and $2,000,000 general aggregate (applying per location) for bodily injury (including death and mental anguish) and property damage and $1,000,000 personal and advertising injury. 

(ii) business automobile liability insurance covering liability arising from any auto (including, owned, non-owned, and hired auto, provided
such non-owned and hired auto liability may be satisfied by endorsement to the commercial general liability policy) in an amount of no less than $1,000,000 combined single limit per accident for bodily injury and property damage. 

(iii) workers’ compensation in statutory limits together with employer’s liability insurance in amounts of no less than $1,000,000
each accident, $1,000,000 disease policy limit, and $1,000,000 disease each employee. 
 (iv) umbrella/excess liability insurance on a
follow form basis in amounts of no less than $5,000,000 per occurrence and $5,000,000 annual aggregate (applying per location) in excess of commercial general liability, employer’s liability, and automobile liability insurance policies,
concurrent to, and no more restrictive than such underlying insurance policies. Such policy shall be endorsed to provide that this insurance is primary to, and noncontributory with, any other insurance in which Landlord and any Additional Insured is
an insured, whether such other insurance is primary, excess, self-insurance, or insurance on any other basis, which must cause the umbrella/excess coverage to be vertically exhausted, whereby such coverage is not subject to any “Other
Insurance” provision under Tenant’s umbrella/excess liability policy. The limits of liability may be satisfied by a combination of primary and excess liability insurance. 

  
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 (v) property insurance written on an ISO CP 10 30-Cause of Loss-Special Form, commonly
referred to as the “all risk” policy form, or its equivalent, including, but not limited to, coverage against sprinkler leakage and other damage due to water, fire, windstorm, cyclone, tornado, hail, earthquake, explosion, riot, civil
commotion, aircraft, vehicle, smoke damage, vandalism, and malicious mischief insuring all present and future Tenant’s Property leased by or in the care, custody, and control of Tenant and located in the Premises in an amount of no less than
the full replacement cost thereof, with an agreed amount endorsement (waiving applicable co-insurance clause). “Tenant’s Property” means Tenant’s trade fixtures, equipment, personal property, signage, and Specialty
Alterations (as defined in Section 18(b)). Tenant shall not self-insure. Tenant shall neither have, nor make, any claim against Landlord for any loss or damage to Tenant’s Property, regardless of the cause of the loss or damage,
including, without limitation, fire, explosion, falling plaster, steam, gas, air contaminants or emissions, electricity, electrical or electronic emanations or disturbance, water, rain, snow, or leaks from any part the Building or from the pipes,
appliances, equipment, or plumbing works or from the roof or from any other place, nor shall Landlord be liable for any loss of or damage to property of Tenant or of others entrusted to employees of Landlord. 

(vi) business interruption insurance covering any loss due to the occurrence of any of the hazards required to be insured against by Tenant
pursuant to this Lease, in an amount sufficient to cover Tenant’s monetary obligations under this Lease for a period of at least twelve (12) months. 

(vii) boiler and machinery, if there is a boiler, supplemental air conditioning unit, or pressure object or similar equipment in the Premises.
When applicable, this insurance coverage requirement may be satisfied through the all-risk coverage required in Section 12(b)(v). 

(c) All insurance policies required of Tenant under this Lease, exclusive of workers’ compensation, shall name Landlord, Landlord’s
property manager, Brandywine Realty Trust, and any other applicable party whose name and address have been furnished to Tenant, each as an additional insured (collectively, “Additional Insureds”). All such coverages shall be primary
and any other insurance that may be available to Landlord and any Additional Insured will be excess and noncontributory. Each Additional Insured shall be afforded coverage as broad as if this Lease had expressly covered the claim against the
Additional Insured, and for the greater of the minimum amount called for by this Lease or Tenant’s actual policy limit. 
 (d) Prior to
the Commencement Date (or Tenant’s earlier accessing of the Premises), Tenant shall provide Landlord and/or Landlord’s designated agent with certificates that evidence that all insurance coverages required under this Lease are in place for
the policy periods. Tenant shall also furnish to Landlord and/or Landlord’s designated agent throughout the Term replacement certificates at least thirty (30) days prior to the expiration dates of the then- current policy or policies or,
upon request by Landlord and/or Landlord’s designated agent from time to time, sufficient information to evidence that the insurance required under this Section is in full force and effect. In addition, all such policies shall contain a
provision whereby the same cannot be canceled or materially altered so as to no longer comply with the minimum insurance coverage requirements in this Section 12 without at least thirty (30) days’ prior written notice of such
cancellation or material alteration provided to Landlord, which shall be afforded by policy 

  
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endorsement extending such notice to Landlord. Tenant shall include a waiver of the insurer’s right of subrogation against Landlord and Additional Insureds during the Term in each of
Tenant’s liability and workers’ compensation policies. If Tenant fails to provide Landlord and/or Landlord’s designated agent with a requested insurance certificate as required under this Lease within thirty (30) days after
receipt of Landlord’s written request therefor, Tenant shall pay to Landlord a fee equal to $25.00 for each day that elapses after such thirty (30)-day period until Landlord and/or Landlord’s designated agent receives the requested
certificate. In no event will any acceptance of certificates of insurance by Landlord, or failure of Tenant to provide certificates of insurance as required hereunder, be construed as a waiver or limitation of Tenant’s obligations to maintain
insurance coverage pursuant to this Section 12. All insurance required under this Lease shall be issued by an insurance company that has been in business for at least five (5) years, is authorized to do business in the State, and is
rated “A-/X” or greater by A.M. Best’s Insurance Reports or any successor publication of comparable standing. The limits of any such required insurance shall not in any way limit Tenant’s liability under this Lease or otherwise.
If Tenant fails to maintain such insurance, Landlord may, but shall not be required to, procure and maintain the same, at Tenant’s reasonable expense, which expense shall be reimbursed by Tenant as Additional Rent within thirty (30) days
after written demand. The deductible or self-insured retention amount required under any insurance policy maintained by Tenant shall be the sole responsibility of Tenant and not exceed $25,000, unless otherwise approved by Landlord in writing. 

(e) When Alterations are in process, Tenant shall carry, or cause, any contractor, subcontractor, and design professional to carry the
insurance specified in Section 9. In addition, Tenant shall require its movers and other vendors to procure insurance in like forms and amounts as required herein and deliver to Landlord and/or Landlord’s designated agent a
certificate of insurance naming each Additional Insured as an additional insured, which policies shall be primary and any other insurance that may be available to Landlord and any Additional Insured will be excess and noncontributory. 

(f) Landlord shall obtain and maintain, or cause to be obtained or maintained, the following insurance during the Term: (i) replacement
cost insurance including “all risk” property insurance on the Building and the Project, including without limitation leasehold improvements (exclusive of Tenant’s Property); (ii) commercial general liability insurance (including
bodily injury and property damage) covering Landlord’s operations at the Project in amounts reasonably required by Landlord or any Mortgagee (as defined in Section 16); and (iii) such other insurance as reasonably required by
Landlord or any Mortgagee. 
 (g) Landlord and Tenant shall each include in each of its insurance policies (insuring the Building in case of
Landlord, and insuring Tenant’s Property in the case of Tenant, against loss, damage, or destruction by fire or other casualty) a waiver of the insurer’s right of subrogation against the other party during the Term, and consent to a waiver
of right of recovery pursuant to the terms of this paragraph. Both Landlord and Tenant agree to promptly give each insurance company which has issued to it policies of insurance written notice of the terms of such mutual waivers and to cause such
insurance policies to be properly endorsed, if necessary, to prevent the invalidation thereof by reason of such waivers. Notwithstanding anything to the contrary in this Lease: (I) each party hereby waives, releases, and agrees not to make any
claim against or seek to recover from, the other party with respect to any claim (including a claim for 

  
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negligence) that such party might otherwise have against the other party for loss, damage, or destruction with respect to its property occurring during the Term to the extent to which such party
is, or is required to be, insured under a policy or policies containing a waiver of subrogation or permission to release liability; and (II) all waivers of subrogation and rights of recovery required hereunder shall also apply to each of the
waiving party’s insurance policies’ deductible(s)/self-insured retention(s). Nothing contained in this Section 12(g) shall be deemed to relieve either party of any duty imposed elsewhere in this Lease to repair, restore, or
rebuild, or nullify any abatement of rents provided for elsewhere in this Lease. 
 13. INDEMNIFICATION. 

(a) Except to the extent the release of liability and waiver of subrogation provided in Section 12 above applies, Tenant shall
defend, indemnify, and hold harmless Landlord, Landlord’s property manager, Brandywine Realty Trust, and each of Landlord’s directors, officers, members, partners, trustees, employees, and agents (collectively, “Landlord
Indemnitees”) from and against any and all third-party claims, actions, damages, liabilities, and expenses (including all reasonable costs and expenses (including reasonable attorneys’ fees)) to the extent arising out of or from or
related to: (i) any breach or default of any of Tenant’s obligations under this Lease; (that continues beyond the expiration of all applicable notice and/or cure periods); (ii) any negligence or willful act or omission of Tenant, any
Tenant Indemnitees (as defined below), or any Tenant Agent; and (iii) except to the extent arising from Landlord’s or the Landlord Indemnitee’s or Landlord’s contractor’s negligence or willfill misconduct, any acts or
omissions occurring at, or the condition, use, or operation of, the Premises. If Tenant fails to promptly defend a Landlord Indemnitee following written demand by the Landlord Indemnitee, the Landlord Indemnitee shall defend the same at
Tenant’s expense, by retaining or employing counsel reasonably satisfactory to such Landlord Indemnitee. 
 (b) Except to the extent the
release of liability and waiver of subrogation provided in Section 12 above applies, Landlord shall defend, indemnify, and hold harmless Tenant and each of Tenant’s directors, officers, members, partners, trustees, employees, and
agents (collectively, “Tenant Indemnitees”) from and against any and all third-party claims, actions, damages, liabilities, and expenses (including all reasonable costs and expenses (including reasonable attorneys’ fees)) to
the extent arising out of or from or related to: (i) any breach or default of any of Landlord’s obligations under this Lease (that continues beyond the expiration of all applicable notice and/or cure periods); and (ii) any negligence
or willful misconduct of Landlord or any Landlord Indemnitees or Landlord’s contractors. If Landlord fails to promptly defend a Tenant Indemnitee following written demand by the Tenant Indemnitee, the Tenant Indemnitee shall defend the same at
Landlord’s expense, by retaining or employing counsel reasonably satisfactory to such Tenant Indemnitee. 
 (c) Landlord’s and
Tenant’s obligations under this Section shall not be limited by the amount or types of insurance maintained or required to be maintained under this Lease. The provisions of this Section shall survive the Expiration Date. 

  
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 14. CASUALTY DAMAGE. If there occurs any casualty to the Project and:
(i) insurance proceeds are unavailable to Landlord or are insufficient to restore the Project to substantially its pre-casualty condition; or (ii) more than thirty percent (30%) of the total area of the Building is damaged, Landlord
shall have the right to terminate this Lease and all the unaccrued obligations of the parties hereto, by sending written notice of such termination to Tenant within sixty (60) days after such casualty. Such notice shall specify a termination
date not fewer than thirty (30) nor more than ninety (90) days after such notice is given to Tenant. If there occurs any casualty to the Premises and: (i) in Landlord’s reasonable judgment, the repair and restoration work would
require more than 210 consecutive days to complete after the casualty (assuming normal work crews not engaged in overtime); or (ii) the casualty occurs during the last twelve (12) months of the Term, Landlord and Tenant shall each have the
right to terminate this Lease and all the unaccrued obligations of the parties hereto, by sending written notice of such termination to the other party within sixty (60) days after the date of such casualty. Such notice shall specify a
termination date not fewer than thirty (30) nor more than ninety (90) days after such notice is given to the other party, but in no event shall the termination date be after the last day of the Term. Notwithstanding the foregoing, if the
casualty was caused by the criminal act of Tenant or any principal or officer of Tenant, Tenant shall have no right to terminate this Lease due to the casualty. If there occurs any casualty to the Premises and neither party terminates this Lease,
then Landlord shall use commercially reasonable efforts to cause the damage to be repaired (exclusive of Tenant’s Property) to a condition as nearly as practicable to that existing prior to the damage, with commercially reasonable speed and
diligence, subject to delays that may arise by reason of adjustment of the loss under insurance policies, Laws, and Force Majeure Events. If this Lease is not terminated pursuant to this paragraph and Landlord fails to complete the repair or
restoration work within ninety (90) days after Landlord’s estimated date for completion of the repair and restoration work (subject to extension for delays caused by Tenant and Force Majeure Events), then Tenant shall have the right to
terminate this Lease by sending at least thirty (30) days’ prior written notice to Landlord within thirty (30) days after such estimated date of completion, provided this Lease shall remain in full force and effect and Tenant shall no
longer have the right to terminate this Lease if Landlord delivers possession of the Premises to Tenant within thirty (30) days after Landlord’s receipt of Tenant’s termination notice. Landlord shall not be liable for any
inconvenience or annoyance to Tenant or Tenant Indemnitees, injury to Tenant’s business, or pain and suffering, resulting in any way from such damage or the repair thereof. Notwithstanding the foregoing, Tenant’s obligation to pay Fixed
Rent and Additional Rent shall be equitably adjusted or abated during the period (if any) during which Tenant is not reasonably able to use the Premises or an applicable portion thereof as a result of such casualty. Tenant shall have no right to
terminate this Lease as a result of any damage or destruction of the Premises, except as expressly provided in this Section. The provisions of this Lease, including this Section, constitute an express agreement between Landlord and Tenant with
respect to any and all damage to, or destruction of, all or any part of the Premises, and any Law with respect to any rights or obligations concerning damage or destruction in the absence of an express agreement between the parties, and any other
statute or regulation, now or hereafter in effect, shall have no application to this Lease or any damage or destruction to all or any part of the Premises. 

15. CONDEMNATION. If a taking renders the Building reasonably unsuitable for the Permitted Use, this Lease shall, at either
party’s option exercised by written notice to the other within thirty (30) days after such taking, terminate as of the date title to condemned real estate vests in the condemner, the Rent herein reserved shall be apportioned and paid in
full by Tenant to Landlord to such date, all Rent prepaid for period beyond that date shall forthwith be repaid by Landlord to Tenant, and neither party shall thereafter have any liability for any 

  
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unaccrued obligations hereunder; provided, however, a condition to the exercise by Tenant of such right to terminate shall be that the portion of the Premises taken shall be of such
extent and nature as materially to handicap, impede, or impair Tenant’s use of the balance of the Premises for its normal business operations. If this Lease is not terminated after a condemnation, then notwithstanding anything to the contrary
in this Lease, Fixed Rent and Additional Rent shall be equitably reduced in proportion to the area of the Premises that has been taken for the balance of the Term. Tenant shall have the right to make a claim against the condemner for moving
expenses, business dislocation damages and loss of business to the extent that such claim does not reduce the sums otherwise payable by the condemner to Landlord. 

16. SUBORDINATION: ESTOPPEL CERTIFICATE. 

(a) Provided that Tenant’s right of possession of the Premises shall not be disturbed by the Mortgagee so long as there is no Event of
Default under this Lease, this Lease shall be subordinate at all times to the lien of any mortgages and deeds of trust now or hereafter placed upon the Premises, Building, and/or Project and land of which they are a part (a
“Mortgage”) without the necessity of any further instrument or act on the part of Tenant to effectuate such subordination. Notwithstanding the foregoing, to the extent that there is a subordination, non-disturbance, and attornment
agreement executed by Tenant and Mortgagee, the terms of the subordination, non-disturbance, and attornment agreement shall control. Tenant further agrees to execute and deliver within twenty (20) days after demand such further instrument
evidencing such subordination and attornment as shall be reasonably required by any Mortgagee. If Landlord shall be or is alleged to be in default of any of its obligations owing to Tenant under this Lease, Tenant shall give to the holder (the
“Mortgagee”) of any mortgage or deed of trust now or hereafter placed upon the Premises, Building, and/or Project whose name and address has been furnished to Tenant, notice by overnight mail of any such default that Tenant shall
have served upon Landlord. Tenant shall not be entitled to exercise any right or remedy as there may be because of any default by Landlord without having given such notice to the Mortgagee. If Landlord shall fail to cure such default, the Mortgagee
shall have thirty (30) additional days within which to cure such default or such longer period as may be reasonably necessary to complete the cure provided Mortgagee is proceeding diligently to cure such default. Notwithstanding the foregoing,
any Mortgagee may at any time subordinate its mortgage to this Lease, without Tenant’s consent, by notice in writing to Tenant, and thereupon this Lease shall be deemed prior to such Mortgage without regard to their respective dates of
execution and delivery, and in that event the Mortgagee shall have the same rights with respect to this Lease as though it had been executed prior to the execution and delivery of the Mortgage. 

(b) Tenant shall attorn to any foreclosing mortgagee, purchaser at a foreclosure sale or by power of sale, or purchaser by deed in lieu of
foreclosure. If the holder of a superior mortgage shall succeed to the rights of Landlord, then at the request of such party so succeeding to Landlord’s rights (herein sometimes called successor landlord), Tenant shall attorn to and recognize
such successor landlord as Tenant’s landlord under this Lease and shall promptly, without payment to Tenant of any consideration therefor, execute and deliver any instrument that such successor landlord may reasonably request to evidence such
attornment. Upon such attornment, this Lease shall continue in full force and effect as, or as if it were, a direct lease between the successor landlord and Tenant upon all of the terms, conditions, and covenants as are set forth in this Lease and
shall be applicable after such attornment, except that 

  
 24 

 
the successor landlord shall not be bound by any modification of this Lease not approved by the successor landlord, or by any previous prepayment of more than one month’s rent, unless such
modification or prepayment shall have been expressly approved in writing by the holder of the superior mortgage through or by reason of which the successor landlord shall have succeeded to the rights of Landlord. With respect to any assignment by
Landlord of Landlord’s interest in this Lease, or the rents payable hereunder, conditional in nature or otherwise, which assignment is made to any Mortgagee, Tenant agrees that the execution thereof by Landlord, and the acceptance thereof by
the Mortgagee, shall never be deemed an assumption by such Mortgagee of any of the obligations of Landlord hereunder, unless such Mortgagee shall, by written notice sent to Tenant, specifically elect, or unless such Mortgagee shall foreclose the
Mortgage and take possession of the Premises. Tenant, upon receipt of written notice from a Mortgagee that such Mortgagee is entitled to collect Rent hereunder may in good faith remit such Rent to Mortgagee without incurring liability to Landlord
for the nonpayment of such Rent. The provisions for attornment set forth in this Section 16(b) shall be self-operative and shall not require the execution of any further instrument. However, if Landlord reasonably requests a further
instrument confirming such attornment, Tenant shall execute and deliver such instrument within 10 days after receipt of such request. 
 (c)
Tenant must at any time and from time to time, within ten (10) business days after receipt of Landlord’s written request, execute and deliver to Landlord an estoppel certificate certifying all reasonably requested information pertaining to
this Lease. 
 17. DEFAULT AND REMEDIES. 

(a) An “Event of Default” shall be deemed to exist and Tenant shall be in default hereunder if: (i) Tenant fails to pay
any Rent when due and such failure continues for more than five (5) business days after Landlord has given Tenant written notice of such failure (such notice being in lieu of, and not in addition to, any applicable statutory notice);
provided, however, in no event shall Landlord have any obligation to give Tenant more than two (2) such notices in any twelve (12)-month period, after which there shall be an Event of Default if Tenant fails to pay any Rent
when due, regardless of Tenant’s receipt of notice of such nonpayment, and, provided further, there shall be an automatic Event of Default if Tenant fails to pay any Rent when due and the automatic stay of bankruptcy precludes
issuance of a default notice; (ii) Tenant fails to bond over a mechanic’s or materialmen’s lien within thirty (30) days after Landlord’s demand; (iii) there is any assignment or subletting (regardless of whether the
same might be void under this Lease) in violation of the terms of this Lease; (iv) the occurrence of any default beyond any applicable notice and/or cure period under any guaranty executed in connection with this Lease; (v) Tenant fails to
deliver any Landlord-requested estoppel certificate or subordination agreement within five (5) business days after receipt of notice that such document was not received within the time period required under this Lease; (vi) there is a
filing of a voluntary petition for relief by Tenant or any guarantor, or the filing of a petition against Tenant or any guarantor in a proceeding under the federal bankruptcy or other insolvency laws that is not withdrawn or dismissed within
forty-five (45) days thereafter, or Tenant’s rejection of this Lease after such a filing, or, under the provisions of any law providing for reorganization or winding up of corporations, the assumption by any court of competent jurisdiction
of jurisdiction, custody, or control of Tenant or any substantial part of its property, or of any guarantor, where such jurisdiction, custody, or control remains in force, unrelinquished, 

  
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unstayed, or unterminated for a period of forty-five (45) days, or the death or ceasing of existence of Tenant or any guarantor, or the commencement of steps or proceedings toward the
dissolution, winding up, or other termination of the existence of Tenant or any guarantor, or toward the liquidation of either of their respective assets, or the evidence of the inability of Tenant or any guarantor to pay its debts as they come due,
including without limitation an admission in writing of its inability to pay its debts when due, or any judgment docketed against any guarantor which is not paid, bonded, or otherwise discharged within forty-five (45) days; or (vii) Tenant
fails to observe or perform any of Tenant’s other agreements or obligations under this Lease and such failure continues for more than thirty (30) days after Landlord gives Tenant written notice of such failure(not to exceed sixty
(60) days), provided Tenant immediately commences and thereafter proceeds with all due diligence and in good faith to cure such failure. 

(b) Upon the occurrence of an Event of Default, Landlord, in addition to the other rights or remedies it may have under this Lease, at law, or
in equity, and without prejudice to any of the same, shall have the option, without any notice to Tenant and with or without judicial process, to pursue any one or more of the following remedies: 

(i) Landlord shall have the right to terminate this Lease, in which event Tenant shall immediately surrender the Premises to Landlord, and
Tenant shall pay Landlord upon demand for all losses and damages that Landlord suffers or incurs by reason of such termination, including damages in an amount equal to the total of: (A) the costs of repossessing the Premises and all other
expenses incurred by Landlord in connection with Tenant’s default, plus the Administrative Fee; (B) the unpaid Rent earned as of the date of termination; (C) all Rent for the period that would otherwise have constituted the remainder
of the Term minus the fair market rental value of the Premises (as reasonably determined by Landlord as of the time of such termination) for the remainder of the Term, with such resulting amount being discounted to present value at a rate of
4% per annum; and (D) all other sums of money and damages owing by Tenant to Landlord. The “Administrative Fee” means fifteen percent (15%) of the reasonable costs incurred by Landlord in curing Tenant’s default
or performing Tenant’s obligations hereunder. 
 (ii) Landlord shall have the right to terminate Tenant’s right of possession (but
not this Lease) and may repossess the Premises by forcible detainer or forcible entry and detainer suit or otherwise, without demand or notice of any kind to Tenant and without terminating this Lease. If Tenant receives written notice of a
termination of its right to possession, such notice will serve as both a notice to vacate, notice to pay or quit, and a demand for possession of, the Premises, and Landlord may immediately thereafter initiate a forcible detainer action without any
further demand or notice of any kind to Tenant. 
 (iii) Landlord shall have the right to enter and take possession of all or any portion of
the Premises without electing to terminate this Lease, in which case Landlord shall have the right to relet all, or any portion of the Premises on such terms as Landlord deems advisable. Landlord will not be required to incur any expenses to relet
all or any portion of the Premises, although Landlord may at its option incur customary leasing commissions or other costs for the account of Tenant as Landlord shall deem necessary or appropriate to relet. In no event will the failure of Landlord
to relet all or any portion of the Premises reduce Tenant’s liability for Rent or damages. Upon the occurrence of an Event of Default, Landlord shall use 

  
 26 

 
commercially reasonable efforts to mitigate its damages. However, Landlord shall not be required to give any special preference or priority to reletting the Premises over other vacant space in
the Building, Landlord shall be deemed to have used commercially reasonable efforts if it uses the same efforts in marketing the Premises as used in marketing other vacant space at the Building, and in no event shall Landlord be responsible or
liable for any failure to relet the Premises or any part thereof, or for any failure to collect any rent due upon a reletting. Landlord’s rejection of a prospective replacement tenant based on an offer of rentals below Landlord’s published
rates for new leases of comparable space at the Building at the time in question, or below the rates provided in this Lease or containing terms less favorable than those contained herein, shall not give rise to a claim by Tenant that Landlord failed
to mitigate its damages. 
 (iv) Landlord shall have the right to enter the Premises without terminating this Lease and without being liable
for prosecution or any claim for damages therefor and maintain the Premises and repair or replace any damage thereto or do anything for which Tenant is responsible hereunder. Tenant shall reimburse Landlord immediately upon demand for any reasonable
out-of-pocket costs which Landlord incurs in thus effecting Tenant’s compliance under this Lease, and Landlord shall not be liable to Tenant for any damages with respect thereto. 

(v) Landlord shall have the right to continue this Lease in full force and effect, whether or not Tenant shall have abandoned the Premises. If
Landlord elects to continue this Lease in full force and effect pursuant to this Section, then Landlord shall be entitled to enforce all of its rights and remedies under this Lease, including the right to recover Rent as it becomes due.
Landlord’s election not to terminate this Lease pursuant to this Section or pursuant to any other provision of this Lease, at law or in equity, shall not preclude Landlord from showing the Premises to potential tenants, subsequently electing to
terminate this Lease, or pursuing any of its other remedies. 
 (c) Upon the occurrence of an Event of Default, Tenant shall be liable to
Landlord for, and Landlord shall be entitled to recover: (i) all Rent accrued and unpaid as of the termination date; (ii) all reasonable costs and expenses incurred by Landlord in recovering possession of the Premises, including legal
fees, and removal and storage of Tenant’s property; (iii) the costs and expenses of restoring the Premises to the condition in which the same were to have been surrendered by Tenant as of the Expiration Date; (iv) the costs of
reletting commissions; (v) all reasonable legal fees and court costs incurred by Landlord in connection with the Event of Default; and (vi) the unamortized portion (as reasonably determined by Landlord) of brokerage commissions and
consulting fees incurred by Landlord, and tenant concessions including free rent given by Landlord, in connection with this Lease. Upon the occurrence of an Event of Default and notwithstanding Section 1(a) above, the monthly Fixed Rent
payable for the Abatement Period shall equal the amount of Fixed Rent payable immediately following the Fixed Rent Start Date. 
 (d) Any
amount payable by Tenant under this Lease that is not paid within thirty (30) days when due shall bear interest at the rate of one percent (1%) per month until paid by Tenant to Landlord. If Tenant fails to pay Rent when due on
three (3) or more occasions during the Term, Landlord shall have the right to require Tenant to pay all future Rent by ACH debit of funds, in which case Tenant shall complete Landlord’s then-current forms authorizing Landlord to
automatically debit Tenant’s bank account. 

  
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 (e) Neither any delay or forbearance by Landlord in exercising any right or remedy hereunder
nor Landlord’s undertaking or performing any act that Landlord is not expressly required to undertake under this Lease shall be construed to be a waiver of Landlord’s rights or to represent any agreement by Landlord to thereafter undertake
or perform such act. Landlord’s waiver of any breach by Tenant of any covenant or condition herein contained (which waiver shall be effective only if so expressed in writing by Landlord) or Landlord’s failure to exercise any right or
remedy in respect of any such breach shall not constitute a waiver or relinquishment for the future of Landlord’s right to have any such covenant or condition duly performed or observed by Tenant, or of Landlord’s rights arising because of
any subsequent breach of any such covenant or condition, nor bar any right or remedy of Landlord in respect of such breach or any subsequent breach. 

(f) If Tenant defaults in the performance of any covenant, agreement, term, provision, or condition contained in this Lease, Landlord, in
addition to any other rights and remedies it has under this Lease and without thereby waiving such default, may perform the same for the account of and at the expense of Tenant (but shall not be obligated to do so), without notice in a case of
emergency and in any other case if such default continues after five (5) days from the date that Landlord gives written notice to Tenant of its intention to do so. Landlord may invoice Tenant for all amounts paid by Landlord and all losses,
costs, and expenses incurred by Landlord in connection with any such performance by Landlord pursuant to this paragraph, plus the Administrative Fee, including, without limitation, all amounts paid and costs and expenses incurred by Landlord for any
property, material, labor, or services provided, furnished, or rendered, or caused to be provided, furnished, or rendered, by Landlord to Tenant, and shall amount shall be due and payable by Tenant to Landlord as Additional Rent within ten (10)
days after Tenant receives the invoice. Any reservation of a right by Landlord to enter upon the Premises and to make or perform any repairs, alterations, or other work in, to, or about the Premises, which, in the first instance, is Tenant’s
obligation pursuant to this Lease, shall not be deemed to impose any obligation on Landlord to do so, render Landlord liable to Tenant or any third party for the failure to do so, or relieve Tenant from any obligation to indemnify Landlord as
otherwise provided elsewhere in this Lease. 
 (g) The rights granted to Landlord in this Section shall be cumulative of every other right or
remedy provided in this Lease or which Landlord may otherwise have at law or in equity or by statute, and the exercise of one or more rights or remedies shall not prejudice or impair the concurrent or subsequent exercise of other rights or remedies
or constitute a forfeiture or waiver of Rent or damages accruing to Landlord by reason of any Event of Default under this Lease. Landlord shall have all rights and remedies now or hereafter existing at law or in equity with respect to the
enforcement of Tenant’s obligations hereunder and the recovery of the Premises. No right or remedy herein conferred upon or reserved to Landlord shall be exclusive of any other right or remedy, but shall be cumulative and in addition to all
other rights and remedies given hereunder or now or hereafter existing at law or in equity. Landlord shall be entitled to injunctive relief in case of the violation, or attempted or threatened violation, of any covenant, agreement, condition or
provision of this Lease, or to a decree compelling performance of any covenant, agreement, condition or provision of this Lease. 

  
 28 

 (h) No payment by Tenant or receipt by Landlord of a lesser amount than any payment of Fixed
Rent or Additional Rent herein stipulated shall be deemed to be other than on account of the earliest stipulated Fixed Rent or Additional Rent due and payable hereunder, nor shall any endorsement or statement or any check or any letter accompanying
any check or payment as Rent be deemed an accord and satisfaction. Landlord may accept such check or payment without prejudice to Landlord’s right to recover the balance of such Rent or pursue any other right or remedy provided for in this
Lease, at law or in equity, and acceptance of such partial payment shall be deemed subject to Landlord’s reservation of all rights. 

(i) Tenant further waives the right to any notices to quit as may be specified in the Landlord and Tenant Act of Pennsylvania, Act of
April 6,1951, as amended, or any similar or successor provision of law, and agrees that five (5) days’ notice shall be sufficient in any case where a longer period may be statutorily specified. 

(j) In addition to, and not in lieu of any of the foregoing rights granted to Landlord: 

(1) WHEN THIS LEASE OR TENANT’S RIGHT OF POSSESSION SHALL BE TERMINATED BY COVENANT OR CONDITION BROKEN, OR FOR ANY OTHER REASON,
EITHER DURING THE TERM OF THIS LEASE OR ANY RENEWAL OR EXTENSION THEREOF, AND ALSO WHEN AND AS SOON AS THE TERM HEREBY CREATED OR ANY EXTENSION THEREOF SHALL HAVE EXPIRED, IT SHALL BE LAWFUL FOR ANY ATTORNEY AS ATTORNEY FOR TENANT TO FILE AN
AGREEMENT FOR ENTERING IN ANY COMPETENT COURT AN ACTION TO CONFESS JUDGMENT IN EJECTMENT AGAINST TENANT AND ALL PERSONS CLAIMING UNDER TENANT, WHEREUPON, IF LANDLORD SO DESIRES, A WRIT OF EXECUTION OR OF POSSESSION MAY ISSUE FORTHWITH, WITHOUT ANY
PRIOR WRIT OF PROCEEDINGS, WHATSOEVER, AND PROVIDED IF FOR ANY REASON AFTER SUCH ACTION SHALL HAVE BEEN COMMENCED THE SAME SHALL BE DETERMINED AND THE POSSESSION OF THE PREMISES HEREBY DEMISED REMAIN IN OR BE RESTORED TO TENANT, LANDLORD SHALL HAVE
THE RIGHT UPON ANY SUBSEQUENT DEFAULT OR DEFAULTS, OR UPON THE TERMINATION OF THIS LEASE AS HEREINBEFORE SET FORTH, TO BRING ONE OR MORE ACTION OR ACTIONS AS HEREINBEFORE SET FORTH TO RECOVER POSSESSION OF THE SAID PREMISES. 

(2) In any action to confess judgment in ejectment, Landlord shall first cause to be filed in such action an affidavit made by it or
someone acting for it setting forth the facts necessary to authorize the entry of judgment, of which facts such affidavit shall be conclusive evidence, and if a true copy of this Lease (and of the truth of the copy such affidavit shall be sufficient
evidence) be filed in such action, it shall not be necessary to file the original as a warrant of attorney, any rule of Court, custom or practice to the contrary notwithstanding. Tenant represents to Landlord that it has a gross income of at least
$10,000. 

  
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 TENANT WAIVER. TENANT SPECIFICALLY ACKNOWLEDGES THAT TENANT HAS VOLUNTARILY, KNOWINGLY,
AND INTELLIGENTLY WAIVED CERTAIN DUE PROCESS RIGHTS TO A PREJUDGMENT HEARING BY AGREEING TO THE TERMS OF THE FOREGOING PARAGRAPHS REGARDING CONFESSION OF JUDGMENT. TENANT FURTHER SPECIFICALLY AGREES THAT IN THE EVENT OF DEFAULT, LANDLORD MAY PURSUE
MULTIPLE REMEDIES INCLUDING OBTAINING POSSESSION PURSUANT TO A JUDGMENT BY CONFESSION. FURTHERMORE, TENANT SPECIFICALLY WAIVES ANY CLAIM AGAINST LANDLORD AND LANDLORD’S COUNSEL FOR VIOLATION OF TENANT’S CONSTITUTIONAL RIGHTS IN THE EVENT
THAT JUDGMENT IS CONFESSED PURSUANT TO THIS LEASE. 
  

			
	TENANT: CABALETTA BIO, INC.
		
	By:	 	 /s/ Steven Nichtberger

	Name:	 	Steven Nichtberger
	Title:	 	CEO
	Date:	 	2/8/2019

 (k) If Landlord defaults in the performance of any of its maintenance or repair obligations under this
Lease, Tenant may send to Landlord written notice thereof, which notice must identify with reasonable specificity the default and Tenant’s remedies under this paragraph (“Reminder Notice”). If Landlord fails to either:
(a) dispute the existence of such default within five (5) business days; or (b) cure such default within Landlord’s Cure Period, then Tenant will have all rights and remedies available at law or in equity for a landlord default.
“Landlord’s Cure Period” means thirty (30) days after Landlord’s receipt of a Reminder Notice, provided if cure cannot be reasonably effected by Landlord within such thirty (30)-day period, Landlord’s Cure
Period includes such additional time as may be reasonably necessary for Landlord to cure, provided Landlord commences to cure within such thirty (30)-day period and diligently prosecutes such cure to completion. 

18. SURRENDER: HOLDOVER. 

(a) By no later than the Expiration Date or earlier termination of Tenant’s right to possession of the Premises (such earlier date, the
“Surrender Date”). Tenant shall vacate and surrender the Premises to Landlord in good order and condition, free of all Transferees, vacant, broom clean, and in conformity with the applicable provisions of this Lease, including
without limitation Sections 9 and 11, ordinary wear and tear excepted and subject to Section 14 and Section 15. Tenant shall have no right to hold over beyond the Surrender Date, and if Tenant does not
vacate as required such failure shall be deemed an Event of Default and Tenant’s occupancy shall not be construed to effect or constitute anything other than a tenancy at sufferance. During any period of occupancy beyond the Surrender Date, the
amount of Rent owed by Tenant to Landlord will be the Holdover Percentage of the Rent for the month immediately prior to the Expiration Date, without prorating for any partial month of holdover, and except that any provisions in this Lease that
limit the amount or defer the payment of 

  
 30 

 
Additional Rent are null and void. The “Holdover Percentage” equals: (i) 150% for the first two (2) months of holdover; and (ii) 200% for any period of holdover
beyond two (2) months. The acceptance of Rent by Landlord or the failure or delay of Landlord in notifying or evicting Tenant following the Surrender Date shall not create any tenancy rights in Tenant and any such payments by Tenant may be
applied by Landlord against its reasonable costs and expenses, including reasonable attorneys’ fees, incurred by Landlord as a result of such holdover. The provisions of this Section shall not constitute a waiver by Landlord of any right of
reentry as set forth in this Lease; nor shall receipt of any Rent or any other act in apparent affirmance of the tenancy operate as a waiver of Landlord’s right to terminate this Lease for a breach of any of the terms, covenants, or obligations
herein on Tenant’s part to be performed. No option to extend this Lease shall have been deemed to have occurred by Tenant’s holdover, and any and all options to extend this Lease or expand the Premises shall be deemed terminated and of no
further effect as of the first date that Tenant holds over. In addition, if Tenant fails to vacate and surrender the Premises as herein required, then Tenant shall indemnify, defend, and hold harmless Landlord from and against any and all costs,
losses, expenses, or liabilities incurred as a result of or related to such failure, including without limitation, claims made by any succeeding tenant and real estate brokers’ claims and reasonable attorneys’ fees. Notwithstanding the
foregoing, Tenant shall have no liability for consequential damages, including claims made by any succeeding tenant, unless Tenant fails to vacate and surrender the Premises as required herein within thirty (30) days after receipt of
Landlord’s notice to vacate (which notice to vacate shall notify Tenant that its failure to timely vacate the Premises may result in lost leasing opportunities for Landlord and subject Tenant to liability for consequential damages).
Tenant’s obligation to pay Rent and to perform all other Lease obligations for the period up to and including the Surrender Date, and the provisions of this Section, shall survive the Expiration Date. In no way shall the remedies to Landlord
set forth above be construed to constitute liquidated damages for Landlord’s losses resulting from Tenant’s holdover. 
 (b) Prior
to the Surrender Date, Tenant, at Tenant’s expense, shall remove from the Premises Tenant’s Property and restore in a good and workmanlike manner any damage to the Premises and/or the Building caused by such removal or replace the damaged
component of the Premises and/or the Building if such component cannot be restored as aforesaid as reasonably determined by Landlord. Notwithstanding the foregoing, Tenant shall not be required to remove a Specialty Alteration if at the time Tenant
requests Landlord’s consent to such Specialty Alteration, Tenant provides Landlord with written notification that Tenant desires to not be required to remove such Specialty Alteration and Landlord consents in writing to Tenant’s
non-removal request. A “Specialty Alteration” means an Alteration that: (i) Landlord required to be removed in connection with Landlord’s consent to making such Alteration; or (ii) is not Building standard, including
without limitation kitchens (other than a pantry installed for the use of Tenant’s employees only), executive restrooms, computer room installations, supplemental HVAC equipment and components, safes, vaults, libraries or file rooms requiring
reinforcement of floors, internal staircases, slab penetrations, non-Building standard life safety systems, security systems, specialty door locksets (such as cipher locks) or lighting, and any demising improvements done by or on behalf of Tenant
after the Commencement Date. If Tenant fails to remove any of Tenant’s Property, as required herein, the same shall be deemed abandoned and Landlord, at Tenant’s reasonable expense, may remove and dispose of same and repair and restore any
damage caused thereby, or, at Landlord’s election, such Tenant’s Property, shall become Landlord’s property. Tenant shall not remove any Alteration (other than Specialty Alterations) from the Premises without the prior written consent
of Landlord, which consent shall not be unreasonably withheld, conditioned or delayed. 

  
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 19. RULES AND REGULATIONS. Tenant covenants that Tenant and Tenant Agents shall
comply with the rules and regulations set forth on Exhibit E attached hereto. Landlord shall have the right to rescind and/or augment any of the rules and regulations and to make such other and further written rules and regulations as in
the reasonable judgment of Landlord shall from time to time be needed for the safety, protection, care, and cleanliness of the Project, the operation thereof, the preservation of good order therein, and the protection and comfort of its tenants,
their agents, employees, and invitees, which when delivered to Tenant shall be binding upon Tenant in a like manner as if originally prescribed. In the event of an inconsistency between the rules and regulations and this Lease, the provisions of
this Lease shall control. Landlord shall not have any liability to Tenant for any failure of any other tenants to comply with any of the rules and regulations, but Landlord shall use commercially reasonable efforts to enforce the rules and
regulations equally against all office tenants and occupants of the Building, subject to the terms of applicable leases. 
 20.
GOVERNMENTAL REGULATIONS. 
 (a) Tenant shall not use, generate, manufacture, refine, transport, treat, store, handle, dispose, bring,
or otherwise cause to be brought or permit any Tenant Agent to bring, in, on, or about any part of the Project, any hazardous waste, solid waste, hazardous substance, toxic substance, petroleum product or derivative, asbestos, polychlorinated
biphenyl, hazardous material, pollutant, contaminant, or similar material or substance as defined by the Comprehensive Environmental Response Compensation and Liability Act, 42 U.S.C. Sections 9601 et seq., as the same may from time to
time be amended, and the regulations promulgated pursuant thereto (CERCLA), or now or hereafter defined or regulated as such by any other Law (“Hazardous Material”). Notwithstanding the foregoing, Tenant shall be permitted to bring
onto the Premises office cleaning supplies and products normally found in modem offices provided Tenant only brings a reasonable quantity of such supplies and products onto the Premises and Tenant shall at all times comply with all Laws pertaining
to the storage, handling, use, disposal, and application of such supplies and products, and all Laws pertaining to the communication to employees and other third parties of any hazards associated with such supplies and products. Tenant shall not
install any underground or above ground tanks on the Premises. Tenant shall not cause or permit to exist any release, spillage, emission, or discharge of any Hazardous Material on or about the Premises in violation of applicable Laws
(“Release”). In the event of a Release, Tenant shall immediately notify Landlord both orally and in writing, report such Release to the relevant government agencies as required by applicable Law, and promptly remove the Hazardous
Material and otherwise investigate and remediate the Release in accordance with applicable Law and to the satisfaction of Landlord. Landlord shall have the right, but not the obligation, to enter upon the Premises to investigate and/or remediate the
Release in lieu of Tenant, and Tenant shall reimburse Landlord as Additional Rent for the reasonable costs of such remediation and investigation. Tenant shall promptly notify Landlord if Tenant acquires knowledge of the presence of any Hazardous
Material on or about the Premises, except as Tenant is permitted to bring onto the Premises under this Lease. Landlord shall have the right to inspect (upon reasonable notice to Tenant) and assess the Premises for the purpose of determining whether
Tenant is handling any Hazardous Material in violation of this Lease or 

  
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applicable Law, or to ascertain the presence of any Release. In exercising the foregoing rights, Landlord shall use its commercially reasonable efforts not to interfere with Tenant’s use and
occupancy of the Premises. This subsection shall survive the Expiration Date. Landlord represents to Tenant to Landlord’s actual knowledge without independent investigation or inquiry that, as of the date of this Lease, it has no notice the
presence of Hazardous Materials, in, on, or about the Premises or the Building in violation of environmental Laws. Landlord will take all remedial actions required by Laws with respect to any Hazardous Materials, in, on, or about the Building that
are the responsibility of Landlord. 
 (b) Tenant shall, and shall cause Tenant Agents to, use the Premises in compliance with all applicable
Laws. Tenant shall, at its sole cost and expense, promptly comply with each and all of such Laws, except in the case of required changes not triggered by Tenant’s particular use or manner of use or change in use of the Premises, or
Tenant’s Alterations. Without limiting the generality of the foregoing, Tenant shall: (i) obtain, at Tenant’s expense, before engaging in Tenant’s business or profession within the Premises, all necessary licenses and permits
including, but not limited to, state and local business licenses, and permits; and (ii) remain in compliance with and keep in full force and effect at all times all licenses, consents, and permits necessary for the lawful conduct of
Tenant’s business or profession at the Premises. Tenant shall pay all personal property taxes, income taxes, gross receipts taxes, and other taxes, assessments, duties, impositions, and similar charges that are or may be assessed, levied, or
imposed upon Tenant or Tenant’s Property. Tenant shall also comply with all applicable Laws that do not relate to the physical condition of the Premises and with which only the occupant can comply, such as laws governing maximum occupancy,
workplace smoking, VDT regulations, and illegal business operations, such as gambling. The judgment of any court of competent jurisdiction or the admission of Tenant in any judicial, governmental or regulatory action, regardless of whether Landlord
is a party thereto, that Tenant has violated any of such Laws shall be conclusive of that fact as between Landlord and Tenant. 
 (c)
Notwithstanding anything to the contrary in this Lease, if the requirement of any public authority obligates either Landlord or Tenant to expend money in order to bring the Premises and/or any area of the Project into compliance with Laws as a
result of: (i) Tenant’s particular use or Alteration of the Premises; (ii) Tenant’s change in the use of the Premises; (iii) any cause or condition created by or at the instance of Tenant or any Tenant Agent, other than by
Landlord’s performance of any work for or on behalf of Tenant; or (iv) breach of any of Tenant’s obligations hereunder, then Tenant shall bear all costs of bringing the Premises and/or Project into compliance with Laws, whether such
costs are related to structural or nonstructural elements of the Premises or Project. 
 (d) Except to the extent Tenant shall comply as set
forth above, during the Term Landlord shall comply with all applicable Laws regarding the Project (including the Premises), including without limitation compliance with Title III of the Americans with Disabilities Act of 1990,42 U.S.C.
§12181 et seq. and its regulations as to the design and construction of the Common Areas. 

  
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 (e) Each party hereto hereby acknowledges and agrees that it will not knowingly violate any
applicable Laws regarding bribery, corruption, and/or prohibited business practices as they concern each such party’s respective activities under or in connection with this Lease, and each such party will be solely responsible for and will hold
harmless the other party from and against any claims or liabilities in connection with any of such responsible party’s own violations of any such Laws. 

21. NOTICES. Wherever in this Lease it is required or permitted that notice or demand be given or served by either party to this Lease
to or on the other party, such notice or demand will be duly given or served if in writing and either: (i) personally served; (ii) delivered by prepaid nationally recognized courier service (e.g., Federal Express, UPS, and USPS) with
evidence of receipt required for delivery; (iii) delivered by registered or certified mail, return receipt requested, postage prepaid; or (iv) if an email address is provided by the recipient, emailed with confirmation of receipt by the
recipient; in all such cases addressed to the parties at the addresses set forth below. Each such notice will be deemed to have been given to or served upon the party to which addressed on the date the same is delivered or delivery is refused. Each
party has the right to change its address for notices (provided such new address is in the continental United States) by a writing sent to the other party in accordance with this Section, and each party will, if requested, within ten (10) days
confirm to the other its notice address. Notices from Landlord or Tenant may be given by either an agent or attorney acting on behalf of Landlord or Tenant. 
  

					
	Tenant:	  	 Cabaletta Bio, Inc.
 Attn: Steven Nichtberger,
MD
 Cira Centre
 2929 Arch Street

Suite 600
 Philadelphia, PA 19104

Email: steven@cabalettabio.com
	  	 With a copy to:
 Steven Nichtberger, MD

01 Northwick Lane
 Villanova, PA 19085

			
	Landlord:	  	 Brandywine Cira, L.P.
 c/o Brandywine Realty
Trust
 Attn: Jeff DeVouno Evecutive Vice President & Senior Managing Director, RE: Building #150

FMC Tower at Cira Centre South
 2929 Walnut St.,
Suite 1700
 Philadelphia, PA 19104
 Phone No.
610-325-5600
 Email: jeff.devouono@bnreit.com
	  	 With a copy to:
 Email:
Legal.Notices@bdnreit.com

 Notwithstanding anything to the contrary in this Lease, billing statements and the like may be sent by regular mail or
electronic means (such as email) to Tenant’s billing contact without copies. 

  
 34 

					
		  	 Tenant’s billing contact:
 Cabaletta Bio,
Inc.
 Attn: Steven Nichtberger, MD
 Cira Centre

2929 Arch Street
 Suite 600

Philadelphia, PA 19104 Phone:
 Email:
AP@cabalettabio.com
	  	

 22. BROKERS. Landlord and Tenant each represents and warrants to the other that such representing party
has had no dealings, negotiations, or consultations with respect to the Premises or this transaction with any broker or finder other than a Landlord affiliate and Broker. Each party shall indemnify, defend, and hold harmless the other from and
against any and all liability, cost, and expense (including reasonable attorneys’ fees and court costs), arising out of or from or related to its misrepresentation or breach of warranty under this Section. Landlord shall pay Broker a commission
in connection with this Lease pursuant to the terms of a separate written agreement between Landlord and Broker. This Section shall survive the Expiration Date. 

23. LANDLORD’S LIABILITY. Landlord’s obligations hereunder shall be binding upon Landlord only for the period of time that
Landlord is in ownership of the Building, and upon termination of that ownership, Tenant, except as to any obligations that are then due and owing, shall look solely to Landlord’s successor-in-interest in ownership of the Building for the
satisfaction of each and every obligation of Landlord hereunder (so long as Landlord’s successor assumes all of Landlord’s obligations hereunder). Upon request and without charge, Tenant shall attorn to any successor to Landlord’s
interest in this Lease and, at the option of any Mortgagees, to such Mortgagees, so long as such successor entity(ies) agree(s) in writing to assume Landlord’s obligations under this Lease. Landlord may transfer its interest in the Building
without the consent of Tenant, and such transfer or subsequent transfer shall not be deemed a violation on Landlord’s part of any of the terms of this Lease. Landlord shall have no personal liability under any of the terms, conditions, or
covenants of this Lease. Tenant and Tenant Agents shall look solely to the equity of Landlord in the Building, all rents, issues and profits therefrom, and/or the net proceeds actually received therefrom for the satisfaction of any claim, remedy, or
cause of action of any kind whatsoever arising from the relationship between the parties or any rights and obligations they may have relating to the Project, this Lease, or anything related to either, including without limitation as a result of the
breach of any Section of this Lease by Landlord. In addition, no recourse shall be had for an obligation of Landlord hereunder, or for any claim based thereon or otherwise in respect thereof or the relationship between the parties, against any past,
present, or future Landlord Indemnitee (other than Landlord), whether by virtue of any statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such other liability being expressly waived and released by Tenant
with respect to the Landlord Indemnitees (other than Landlord). 
 24. RELOCATION. Landlord, at its sole expense, on at least
six (6) months’ prior written notice to Tenant, may require Tenant to move from the Premises to another suite of substantially comparable size and decor in the Building. In the event of any such relocation, Landlord shall pay all the
reasonable expenses: (a) of preparing and decorating the new premises so that they will be substantially similar to the Premises; (b) of moving Tenant’s 

  
 35 

 
furniture and equipment to the new premises (including Tenant’s data and communication wiring and cabling); and (c) reasonably incurred and documented by Tenant, up to a maximum amount
of $5,000.00, in notifying its clients of such relocation, obtaining new letterhead and business cards, and other incidental expenses related directly to Tenant’ s relocation. Tenant shall execute any reasonable amendment evidencing the terms
of the relocation as Landlord may require in its reasonable discretion. Upon the effective date of the relocation: (i) the description of the Premises set forth in this Lease shall, without further act on the part of Landlord or Tenant, be
deemed amended so that the new premises shall, for all purposes, be deemed the Premises hereunder, and all of the terms, covenants, conditions, provisions, and agreements of this Lease, including those agreements to pay Rent (at the same rate per
rentable square foot except as set forth below), shall continue in full force and effect and shall apply to the new premises; provided, however, in no event shall the Fixed Rent payable by Tenant under the Lease or Tenant’s Share
increase as a result of such relocation (if the new premises are smaller than the Premises, all rental charges which are based upon the square footage of the Premises shall be reduced accordingly); and (ii) Tenant shall move into the new
premises. Notwithstanding the foregoing, Tenant shall have the right to terminate this Lease by written notice to Landlord within thirty (30) calendar days after receipt of Landlord’s notice of relocation; provided, however,
Landlord shall have the right to rescind its relocation notice by notice to Tenant within fifteen (15) calendar days after receipt of Tenant’s notice of termination, in which case the Term and the Premises shall continue as if Landlord
never sent a notice of relocation under this Section 24. If Tenant timely terminates this Lease pursuant to the foregoing and Landlord does not elect to rescind its relocation notice, the Term shall automatically end on the date set
forth in Landlord’s notice as the relocation date as if the Term were originally scheduled to expire on such date, which date shall be deemed the Expiration Date under this Lease. 

25. GENERAL PROVISIONS. 

(a) Provided Tenant has performed all of the terms and conditions of this Lease to be performed by Tenant within all applicable notice and/or
cure periods set forth herein, including the payment of Rent, Tenant shall peaceably and quietly hold and enjoy the Premises for the Term, without hindrance from Landlord or anyone lawfully or equitably claiming by, through, or under Landlord, under
and subject to the terms and conditions of this Lease. 
 (b) Subject to the terms and provisions of Section 10. the respective
rights and obligations provided in this Lease shall bind and inure to the benefit of the parties hereto, their successors and assigns. 
 (c)
This Lease shall be governed in accordance with the Laws of the State, without regard to choice of law principles. Landlord and Tenant hereby consent to the exclusive jurisdiction of the state and federal courts located in the jurisdiction in which
the Project is located. 
 (d) In connection with any litigation or arbitration arising out of this Lease, Landlord or Tenant, whichever is
the prevailing party as determined by the trier of fact in such litigation, shall be entitled to recover from the other party all reasonable costs and expenses incurred by the prevailing party in connection with such litigation, including reasonable
attorneys’ fees. If, in the context of a bankruptcy case, Landlord is compelled at any time to 

  
 36 

 
incur any expense, including attorneys’ fees, in enforcing or attempting to enforce the terms of this Lease or to enforce or attempt to enforce any actions required under the Bankruptcy Code
to be taken by the trustee or by Tenant, as debtor-in-possession, then the sum so paid by Landlord shall be awarded to Landlord by the Bankruptcy Court and shall be immediately due and payable by the trustee or by Tenant’s bankruptcy estate to
Landlord in accordance with the terms of the order of the Bankruptcy Court. 
 (e) This Lease, which by this reference incorporates all
exhibits, riders, schedules, and other attachments hereto, supersedes all prior discussions, proposals, negotiations and discussions between the parties and this Lease contains all of the agreements, conditions, understandings, representations, and
warranties made between the parties hereto with respect to the subject matter hereof, and may not be modified orally or in any manner other than by an agreement in writing signed by both parties hereto or their respective successors-in-interest.
Whenever placed before one or more items, the words “include”, “includes”, and “including” shall mean considered as part of a larger group, and not limited to the item(s) recited. Except to the extent expressly set
forth otherwise in this Lease, neither Landlord, nor anyone acting on Landlord’s behalf, has made any representation, warranty, estimation, or promise of any kind or nature whatsoever relating to the physical condition of the Building or the
land under the Building or suitability, including without limitation, the fitness of the Premises for Tenant’s intended use. If any provisions of this Lease are held to be invalid, void, or unenforceable, the remaining provisions hereof shall
in no way be affected or impaired and such remaining provisions shall remain in full force and effect. 
 (f) TIME IS OF THE ESSENCE UNDER
ALL PROVISIONS OF THIS LEASE, INCLUDING ALL NOTICE PROVISIONS. 
 (g) If Landlord or Tenant is in any way delayed or prevented from
performing any obligation (except, with respect to Tenant, its obligations to pay Rent) due to fire or other casualty (or reasonable delays in the adjustment of insurance claims), acts of terrorism, war or other emergency (including severe weather
emergency), governmental delay beyond what is commercially reasonable (provided the party claiming the delay provides reasonable evidence to the other party that the party claiming the delay is diligently pursuing the approval or permit that is the
subject to the governmental delay), inability to obtain any materials or services, acts of God, strike, lockout or other labor dispute, orders or regulations of any federal, state, county or municipal authority, embargoes, or any other cause beyond
such party’s reasonable control (whether similar or dissimilar to the foregoing events) (each, a “Force Maieure Event”), then the time for performance of such obligation shall be excused for the period of such delay or
prevention (and such party shall not be deemed in default with respect to the performance of its obligations) and extended for a period equal to the period of such delay or prevention. Financial disability or hardship shall never constitute a Force
Majeure Event. No such inability or delay due to a Force Majeure Event shall constitute an actual or constructive eviction, in whole or in part, or entitle Tenant to any abatement or diminution of Rent, or relieve the other party from any of its
obligations under this Lease, or impose any liability upon such party or its agents, by reason of inconvenience or annoyance to the other party, or injury to or interruption of the other party’s business, or otherwise. 

  
 37 

 (h) Excepting payments of Fixed Rent, Operating Expenses, and utilities (which are to be
paid as set forth in Section 4.5. and 6) and unless a specific time is otherwise set forth in this Lease for any Tenant payments, all amounts due from Tenant to Landlord shall be paid by Tenant to Landlord as Additional Rent
within thirty (30) days after receipt of an invoice therefor. 
 (i) Unless Tenant’s financials are publicly available online at no
cost to Landlord, within ten (10) days after written request by Landlord (but not more than once during any twelve (12)-month period except in the event of a sale, financing, or refinancing by Landlord of all or any portion of the
Project), Tenant shall furnish to Landlord, Mortgagee, or Landlord’s prospective mortgagee or purchaser, reasonably requested financial information. In connection therewith and upon Tenant’s request, Landlord and Tenant shall execute a
mutually acceptable confidentiality agreement on Landlord’s form therefor. 
 (j) Tenant represents and warrants to Landlord that:
(i) Tenant was duly organized and is validly existing and in good standing under the Laws of the jurisdiction set forth for Tenant in the first sentence of this Lease; (ii) Tenant is legally authorized to do business in the State;
(iii) the person(s) executing this Lease on behalf of Tenant is(are) duly authorized to do so; and (iv) Tenant has the full corporate or partnership power and authority to enter into this Lease and has taken all corporate or partnership
action, as the case may be, necessary to carry out the transaction contemplated herein, so that when executed, this Lease constitutes a valid and binding obligation enforceable in accordance with its terms. 

(k) If Tenant has removed all or substantially all of Tenant’s Property and there is one (1) month or less remaining in the Term,
Landlord shall have the right to access and make improvements to the Premises in anticipation of reletting without affecting or modifying the Term or Rent, and without any additional notice to or consent of Tenant. Tenant shall have no rights in or
to such improvements. Tenant hereby waives any claim of constructive eviction, early termination of this Lease, or reduction of Rent in connection with Landlord exercising such right. 

(l) Each party hereto represents and warrants to the other that such party is not a party with whom the other is prohibited from doing business
pursuant to the regulations of the Office of Foreign Assets Control (“OFAC”) of the U.S. Department of the Treasury, including those parties named on OFAC’s Specially Designated Nationals and Blocked Persons List. Each party
hereto is currently in compliance with, and shall at all times during the Term remain in compliance with, the regulations of OFAC and any other governmental requirement relating thereto. Each party hereto shall defend, indemnify, and hold harmless
the other from and against any and all claims, damages, losses, risks, liabilities, and expenses (including reasonable attorneys’ fees and costs) incurred by the other to the extent arising from or related to any breach of the foregoing
certifications. The foregoing indemnity obligations shall survive the Expiration Date. 
 (m) Landlord shall have the right, to the extent
required to be disclosed by Landlord or Landlord’s affiliates in connection with filings required by applicable Laws, including without limitation the Securities and Exchange Commission (“SEC”), without notice to Tenant to
include in such securities filings general information relating to this Lease, including, 

  
 38 

 
without limitation, Tenant’s name, the Building, and the square footage of the Premises. Except as required by Law, information relating to rates set forth in the Lease will not be released
without Tenant’s prior written consent. Except as set forth in the preceding sentence, neither Tenant nor Landlord shall issue, or permit any broker, representative, or agent representing either party in connection with this Lease to issue:
(i) any press release; or (ii) any other public disclosure regarding the specific terms of this Lease (or any amendments or modifications hereof), without the prior written approval of the other party, which approval shall not be
unreasonably withheld, conditioned or delayed. The parties acknowledge that the transaction described in this Lease and the terms thereof (but not the existence thereof) are of a confidential nature and shall not be disclosed except to such
party’s employees, attorneys, accountants, consultants, advisors, affiliates, and actual and prospective purchasers, lenders, investors, subtenants and assignees (collectively, “Permitted Parties”), and except as, in the good
faith judgment of Landlord or Tenant, may be required to enable Landlord or Tenant to comply with its obligations under Law or under laws and regulations of the SEC. Neither party may make any public disclosure of the specific terms of this Lease,
except as required by Law, including without limitation SEC laws and regulations, or as otherwise provided in this paragraph. 
 (n) Neither
Tenant, nor anyone acting through, under, or on behalf of Tenant, shall have the right to record this Lease, nor any memorandum, notice, affidavit, or other writing with respect thereto. 

(o) Tenant shall not claim any money damages by way of setoff, counterclaim, or defense, based on any claim that Landlord unreasonably withheld
its consent, in which case Tenant’s sole and exclusive remedy shall be an action for specific performance, injunction, or declaratory judgment. Notwithstanding the foregoing, if a court determines that Landlord acted maliciously or in bad faith
in unreasonably withholding, conditioning, or delaying its consent or approval in an instance where Landlord was obligated not to unreasonably withheld, condition, or delay its consent or approval, then the limitation on damages and remedies
provided for in this paragraph shall have no further application. 
 (p) All requests made to Landlord to perform repairs or furnish
services, supplies, utilities, or freight elevator usage (if applicable), shall be made online to the extent available (currently such requests shall be made via http://etenants.com/, as the same may be modified by Landlord from time to time)
otherwise via email or written communication to Landlord’s property manager for the Building. Whenever Tenant requests Landlord to take any action not required of Landlord under this Lease or give any consent required or permitted to be given
by Landlord under this Lease (for example, a request for a Transfer consent, a consent to an Alteration, or a subordination of Landlord’s lien, but other than a request for services, supplies, or utilities which is governed by
Section 7(b)). Tenant shall pay to Landlord for Landlord’s reasonable administrative and/or professional costs in connection with each such action or consent, including reasonable attorneys’, engineers’ and/or
architects’ fees (as applicable). The foregoing amount shall be paid by Tenant to Landlord within thirty (30) days after Landlord’s delivery to Tenant of an invoice for such amount. Tenant shall pay such amount without regard to
whether Landlord takes the requested action or gives the requested consent. 

  
 39 

 (q) Tenant acknowledges and agrees that Landlord shall not be considered a “business
associate” for any purpose under the Health Insurance Portability and Accountability Act of 1996 and all related implementing regulations and guidance. 

(r) Tenant shall cause any work performed on behalf of Tenant to be performed by contractors who work in harmony, and shall not interfere, with
any labor employed by Landlord or Landlord’s contractors. If at any time any of the contractors performing work on behalf of Tenant does not work in harmony or unreasonably interferes with any labor employed by Landlord, other tenants, or their
respective mechanics or contractors, then the permission granted by Landlord to Tenant to do or cause any work to be done in or about the Premises may be withdrawn by Landlord with forty-eight (48) hours’ written notice to Tenant. 

(s) This Lease may be executed in any number of counterparts, each of which shall be deemed to be an original as against any party whose
signature appears thereon, and all of which shall together constitute one and the same instrument. The submission of this Lease by Landlord to Tenant for examination does not constitute a reservation of or option for the Premises or of any other
space within the Building or in other buildings owned or managed by Landlord or its affiliates. This Lease shall not be binding nor shall either party have any obligations or liabilities or any rights with respect hereto, or with respect to the
Premises, unless and until both parties have executed and delivered this Lease. The parties acknowledge and agree that notwithstanding any law or presumption to the contrary, the exchange of copies of this Lease and signature pages by electronic
transmission shall constitute effective execution and delivery of this Lease for all purposes, and signatures of the parties hereto transmitted and/or produced electronically shall be deemed to be their original signature for all purposes. 

(t) Landlord and persons authorized by Landlord may enter the Premises at all reasonable times upon reasonable advance notice or, in the case
of an emergency, at any time without notice, for any commercially reasonable purpose, including without limitation to inspect the Premises, to make alterations or repairs that Landlord is required to make under this Lease, and to show the Premises
to prospective purchasers, lenders, and prospective Tenants. Landlord shall not be liable for inconvenience to or disturbance of Tenant by reason of any such entry; provided, however, such access shall be done, so far as practicable,
so as to not unreasonably interfere with Tenant’s use of the Premises. 
 (u) If more than one person executes this Lease as Tenant,
each of them is jointly and severally liable for the keeping, observing, and performing of all of the terms, covenants, conditions, provisions, and agreements of this Lease to be kept, observed, and performed by Tenant. 

(v) TO THE EXTENT PERMITTED BY APPLICABLE LAW, LANDLORD AND TENANT HEREBY WAIVE TRIAL BY JURY IN ANY ACTION, PROCEEDING, OR COUNTERCLAIM
BROUGHT BY EITHER AGAINST THE OTHER ON ANY MATTER ARISING OUT OF OR IN ANY WAY CONNECTED WITH THIS LEASE, THE RELATIONSHIP OF LANDLORD AND TENANT, OR TENANT’S USE OR OCCUPANCY OF THE BUILDING, ANY CLAIM OR INJURY OR DAMAGE, OR ANY EMERGENCY OR
OTHER STATUTORY REMEDY WITH RESPECT THERETO. TENANT CONSENTS TO SERVICE OF PROCESS AND ANY PLEADING RELATING TO ANY SUCH ACTION AT 

  
 40 

 
THE PREMISES; PROVIDED, HOWEVER, NOTHING HEREIN SHALL BE CONSTRUED AS REQUIRING SUCH SERVICE AT THE PREMISES. TENANT WAIVES ANY RIGHT TO RAISE ANY NONCOMPULSORY COUNTERCLAIM IN ANY
SUMMARY OR EXPEDITED ACTION OR PROCEEDING INSTITUTED BY LANDLORD. LANDLORD, TENANT, ALL GUARANTORS, AND ALL GENERAL PARTNERS EACH WAIVES ANY OBJECTION TO THE VENUE OF ANY ACTION FILED IN ANY COURT SITUATED IN THE JURISDICTION IN WHICH THE BUILDING
IS LOCATED, AND WAIVES ANY RIGHT, CLAIM, OR POWER UNDER THE DOCTRINE OF FORUM NON CONVENIENS OR OTHERWISE TO TRANSFER ANY SUCH ACTION TO ANY OTHER COURT. 

(w) Except in connection with a Tenant holdover as set forth in, and subject to the terms and conditions in, Section 18 of the
Lease, and notwithstanding anything to the contrary in this Lease, each party waives, and the other shall not be liable to the waiving party for, any claim against the other party or the other party’s agents, invitees, employees, or
contractors, for loss of business opportunity, loss of profits, loss of income, economic loss, consequential damages, or punitive damages; the foregoing waiver shall survive the expiration or sooner termination of this Lease. 

(x) Landlord shall have no security interest or other lien in any equipment, fixtures, furniture, inventory, and other personal property or
fixtures of Tenant situate in the Premises, and Landlord hereby waives and releases any such lien or right to lien. During the Term, Landlord will promptly execute any commercially reasonable form of release of Landlord’s lien as to any
furniture, fixtures, equipment, inventory, and other personal property belonging to Tenant and located in the Premises, subject to Section 25(p) above. 

(y) During the Term and subject to availability and Landlord’s rules and regulations therefor, Tenant’s employees who work in the
Building shall have the nonexclusive, first-come, first-served use of any fitness facilities and cafeterias available to tenants that may from time to time exist in the Building. Tenant acknowledges that no such cafeteria exists on the date of this
Lease. Any user of the fitness facility shall execute Landlord’s standard fitness center use agreement. Neither Landlord nor any Landlord Indemnitee (as defined in Section 13(a)) shall have any liability to Tenant or any Tenant
Agent for any damage, injury, loss, expense, compensation, or claim whatsoever arising out of the use of such fitness facilities and cafeteria. 

26. EXTENSION OPTION. 

(a) Provided: (i) no Event of Default exists; and (ii) this Lease is in full force and effect, Tenant shall have the right to extend
the Term (“Extension Option”) for sixty (60) months beyond the end of the Initial Term (“Extension Term”) by delivering Tenant’s written extension election notice (“Extension Notice”) to
Landlord no later than the Extension Deadline and no earlier than six (6) months prior to the Extension Deadline, with time being of the essence. The “Extension Deadline” means the date that is eight (8) months prior to
the expiration of the Initial Term. The terms and conditions of this Lease during the Extension Term shall remain unchanged except Tenant shall only be entitled to the one (1) Extension Term provided above, the annual Fixed Rent for the
Extension Term shall be the Extension Rent (as defined below), the Expiration Date shall be the last day of the Extension Term (or such earlier 

  
 41 

 
date of termination of this Lease pursuant to the terms hereof), and, except to the extent reflected in the Extension Rent, Landlord shall have no obligation to perform any tenant improvements to
the Premises or provide any tenant improvement allowance to Tenant. Upon Tenant’s delivery of the Extension Notice, Tenant may not thereafter revoke its exercise of the Extension Option. Notwithstanding anything to the contrary in this Lease,
Tenant shall have no right to extend the Term other than or beyond the one (1), sixty (60)-month Extension Term described in this paragraph. 

(b) “Extension Rent” means the fair market extension term base rent for space comparable to the Premises in comparable
buildings in the market in which the Project is located. In determining the Extension Rent, Landlord, Tenant and any broker shall take into account all relevant factors including, without limitation, prevailing market allowances and concessions for
renewing tenants, space measurement methods and loss factors, the lease term, the size of the space, the location of the building(s), parking charges, the amenities offered at the building(s), the age of the building(s), and whether Project Expenses
and other pass-through expenses are on a triple net, base year, expense stop or other basis. In lieu of directly providing any prevailing market allowances and/or concessions, Landlord may elect to reduce the Extension Rent by the economic
equivalent thereof to reflect the fact that such allowances and concessions were not provided directly to Tenant. During the Extension Term, Tenant shall not be entitled to any tenant improvement allowances, free rent periods, or other economic
concessions (if any) that Tenant was entitled to during the prior Term, except to the extent such items are indirectly incorporated into the Extension Rent as set forth in this Section. When the Extension Rent is being determined for the first year
of the Extension Term, the Extension Rent for the second and all subsequent years of the Extension Term shall also be determined in accordance with the same procedures as are set forth herein and based upon the then prevailing annual rent escalation
factor in the applicable leasing market. 
 (c) If Tenant timely exercises the Extension Option and Landlord and Tenant, after using their
good faith efforts to do so, do not agree upon the Extension Rent in writing by the date that is the later of twenty (20) days after Landlord’s receipt of the Extension Notice or three (3) months prior to the Extension Deadline, then
within fifteen (15) days after either party notifies the other in writing that such notifying party desires to determine the Extension Rent in accordance with the procedures set forth in this Section, Landlord and Tenant shall each deliver to
the other party a written statement of such delivering party’s determination of the Extension Rent, together with such supporting documentation as the delivering party desires to deliver. Within ten (10) days after such
fifteen (15)-day period, Landlord and Tenant shall appoint a real estate broker having a minimum of ten (10) years’ experience in the market in which the Project is located who shall select either Landlord’s determination or
Tenant’s determination, whichever the broker finds more accurately reflects the Extension Rent. The broker shall be instructed to notify Landlord and Tenant of such selection within ten (10) days after such broker’s appointment. The
broker shall have no power or authority to select any Extension Rent other than the Extension Rent submitted by Landlord or Tenant nor shall the broker have any power or authority to modify any of the provisions of this Lease, and the decision of
the broker shall be final and binding upon Landlord and Tenant. If Landlord and Tenant do not timely agree in writing upon the appointment of the broker, Landlord shall submit to Tenant the names of three (3) qualified brokers with a minimum of
ten (10) years’ experience in the market in which the Project is located, and Tenant shall have ten (10) days after receiving such names to notify 

  
 42 

 
Landlord of which of the three (3) brokers Tenant selects to determine the Extension Rent. If Tenant fails to timely notify Landlord of Tenant’s selection, Landlord shall have the right
to unilaterally appoint the broker. The fee and expenses of the broker shall be shared equally by Landlord and Tenant. 
 (d) Upon
Tenant’s timely and proper exercise of the Extension Option pursuant to the terms above and satisfaction of the above conditions: (i) the “Term” shall include the Extension Term, subject only to the determination of
Extension Rent; and (ii) upon Landlord’s request, Tenant shall execute prior to the expiration of the then-expiring Term, an appropriate amendment to this Lease, in form and content reasonably satisfactory to both Landlord and Tenant,
memorializing the extension of the Term for the ensuing Extension Term (provided Tenant’s failure to execute such amendment shall not negate the effectiveness of Tenant’s exercise of the Extension Option). 

27. RIGHT OF FIRST OFFER. 

(a) Provided: (i) no Event of Default exists; and (ii) this Lease is in full force and effect, then during the Term (including the
Extension Term) Landlord shall notify Tenant in writing (“Landlord’s ROFO Notice”) when any rentable space located contiguous to and on the same floor as the Premises (“Potential ROFO Space”) becomes available
to lease (as defined below) from Landlord or Landlord reasonably anticipates that such space will become available to lease from Landlord. Landlord’s ROFO Notice shall identify the portion of the Potential ROFO Space that is available to lease
(such identified space, “ROFO Space”), and include the anticipated availability date and basic economic terms for the lease of the ROFO Space and, subject to the terms and provisions of this Section, Tenant shall have the right
(“ROFO”) to lease all (but not less than all) of the ROFO Space by delivering Tenant’s written notice of such election to Landlord (“Tenant’s ROFO Notice”) within ten (10) business days after
Tenant’s receipt of Landlord’s ROFO Notice. Landlord acknowledges and agrees that the term of the Lease with respect to the ROFO Space identified in Landlord’s ROFO Notice shall be coterminous with the term of this Lease with respect
to the Premises (and any renewals thereof). 
 (b) Upon Tenant’s delivery of Tenant’s ROFO Notice, Tenant may not thereafter revoke
Tenant’s exercise of the ROFO. If an Event of Default exists at any time after Landlord receives Tenant’s ROFO Notice but before the first day that Tenant commences to lease the ROFO Space, Landlord, at Landlord’s option, shall have
the right to nullify Tenant’s exercise of the ROFO with respect to the ROFO Space. If Tenant notifies Landlord that Tenant elects not to lease the ROFO Space or if Tenant fails to timely deliver Tenant’s ROFO Notice to Landlord with
respect thereto, then Landlord shall have the right to enter into a lease agreement(s) for the ROFO Space under one or more leases containing such terms as Landlord deems acceptable in Landlord’s sole discretion, and the ROFO shall be void and
have no further force or effect with respect to such space; provided, however, Tenant shall retain its right of first offer rights hereunder with respect to any part of the Potential ROFO Space that was not covered by Landlord’s
ROFO Notice. 

  
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 (c) The ROFO shall be subject, subordinate, and in all respects inferior to the rights of
any third-party tenant leasing space at the Building as of the date of this Lease. Landlord may at any time choose to use any space that is or about to become vacant within the Building for marketing or property management purposes, or as a Building
amenity or Common Area such as a fitness center or conference area, or to lease such space to an existing tenant of Landlord in connection with the relocation of such tenant, without in any such case notifying or offering such space to Tenant or
giving rise to any right of Tenant hereunder. Space is “available to lease” if and when: (i) the lease for any tenant of all or a portion of the space expires or is otherwise terminated, provided space shall not be deemed to be
or become available if the space is assigned or subleased by the tenant of the space, or relet by the tenant or subtenant of the space by renewal, extension, or new lease; and (ii) to the extent that all or a portion of the Potential ROFO Space
is available to lease from Landlord as of the date of this Lease, Landlord has entered into a lease with a third-party tenant for such currently available ROFO Space after the date of this Lease and the term of that lease has expired (including,
without limitation, the expiration of any lease term extension period(s), regardless of whether the extension right or agreement is contained in such lease or is agreed to at any time by Landlord and the tenant under such lease or otherwise) or been
terminated. 
 (d) Except to the extent expressly set forth in Landlord’s ROFO Notice to the contrary, if Tenant elects to lease the
ROFO Space, such space shall become subject to this Lease upon the same terms and conditions as are then applicable to the original Premises, except that Tenant shall take the ROFO Space in “AS IS” condition and Landlord shall have no
obligation to make any improvements or alterations to the ROFO Space, and the term of Tenant’s lease of the ROFO Space shall be coterminous with this Lease (and any renewals thereof). Landlord shall determine the exact location of any demising
walls (if any) for the ROFO Space. Tenant shall not be entitled to any tenant improvement allowances, free rent periods, or other special concessions granted to Tenant with respect to the original Premises. Upon Tenant’s leasing of the ROFO
Space, the “Premises” shall include the ROFO Space and, except as otherwise set forth in this Section, all computations made under this Lease based upon or affected by the rentable area of the Premises shall be recomputed to include
the ROFO Space. 
 (e) If Tenant timely exercises its right to lease the ROFO Space: (i) Tenant’s lease of the ROFO Space shall
commence upon the later of: (A) the date of availability specified in Landlord’s ROFO Notice; or (B) the date Landlord tenders possession of the ROFO Space in vacant condition; and (ii) upon Landlord’s request, Tenant shall
execute an appropriate amendment, in form and content reasonably satisfactory to both Landlord and Tenant, memorializing the expansion of the Premises as set forth in this Section (provided Tenant’s failure to execute such lease or amendment
shall not negate the effectiveness of Tenant’s exercise of the ROFO). 
 28. TENANT CONFESSION CERTIFICATION: Tenant
acknowledges and agrees that any failure of Tenant to execute Section 17 of this Lease shall be an absolute bar from Tenant (or Tenant’s successors or assigns) claiming, alleging or petitioning, including, but not limited to, in any
petition to open said confession, that such Section is invalid and not binding upon Tenant (or Tenant’s successors or assigns). 

[SIGNATURES ON FOLLOWING PAGE] 

  
 44 

 IN WITNESS WHEREOF, the parties hereto have executed this Lease under seal as of the day and
year first- above stated. 
  

									
	 LANDLORD:
 BRANDYWINE CIRA,
L.P.
	 		  	 TENANT:
 CABALETTA BIO,
INC.

				
	By: Brandwine Cira, L.L.C., its general partner	 		  		  	
					
	By:	 	 /s/ Stephen Rush
	 		  	By:	  	 /s/ Steven Nichtberger

	Name:	 	Stephen Rush	 	        	  	Name:	  	Steven Nichtberger
	Title:	 	Vice President	 		  	Title:	  	CEO
	Date:	 	2/11/2019	 		  	Date:	  	2/8/2019

 Exhibits: 
  

			
	Exhibit A:	  	Location Plan of Premises
	Exhibit B:	  	Form of COLT
	Exhibit C:	  	Leasehold Improvements
	Exhibit D:	  	Cleaning Specifications
	Exhibit E:	  	Rules and Regulations

 [Signature page] 

 EXHIBIT B 

FORM OF COLT 
 CONFIRMATION OF
LEASE TERM 
 THIS CONFIRMATION OF LEASE TERM (“COLT”) is made as of
                     between                 
(“Landlord”) and                  (“Tenant”). 

1. Landlord and Tenant are parties !o that certain lease dated (“Lease Document”), with respect to the premises described in the
Lease Document, known as Suite                  consisting of approximately
                 rentable square feet (“Premises”), located at
                . 
 2. All capitalized terms, if not
defined in this COLT, have the meaning give such terms in the Lease Document. 
 3. Tenant has accepted possession of the Premises in their
“AS IS” “WHERE IS” condition and all improvements required to be made by Landlord per the Lease Document have been completed. 

4. The Lease Document provides for the commencement and expiration of the Term of the lease of the Premises, which Term commences and expires
as follows: 
 a. Commencement of the Term of the Premises:
                 
 b. Expiration of the Term of the
Premises:                  
 5. The required amount
of the Security Deposit and/or Letter of Credit per the Lease Document is $                . Tenant has delivered the Security Deposit and/or Letter of Credit per
the Lease Document in the amount of $                . 

6. The Building Number is                  and the Lease
Number is                 . This information must accompany every payment c f Rent made by Tenant to Landlord per the Lease Document. 

 

									
	TENANT:	 		  	LANDLORD:
			
	                                    
        	 		  	                                    
        

									
					
	By:	 	  
	 		  	By:	  	  

	Name:	 	  
	 	        	  	Name:	  	  

	Title:	 	  
	 		  	Title:	  	  

  
 B-1 

 EXHIBIT C 

LEASEHOLD IMPROVEMENTS 
 1.
Landlord will, at its sole cost and expense and using Building-standard materials and finishes, complete the improvements in the Premises shown or described as Landlord Work on Exhibit C-1 attached hereto (“Landlord
Work”). In addition, Landlord will, at Tenant sole cost and expense, complete the improvements in the Premises shown or described as Tenant Work on Exhibit C-1 attached hereto (“Tenant Work”). Landlord Work and
Tenant Work are referred to herein collectively as the “Leasehold Improvements”, and Exhibit C-1 is referred to herein as the “Scope of Work”. The Leasehold Improvements shall expressly not
include any finishes, materials, or improvements not specifically addressed and detailed on the Scope of Work. If any material revision to the Leasehold Improvements is deemed necessary by Landlord, such revision will be submitted to Tenant for
approval, which approval may not be unreasonably withheld, conditioned, or delayed. 
 2. “Substantial Completion” means the
date on which (i) the Leasehold Improvements have been completed except as set forth on the Punch List (as defined below), and (ii) Landlord has obtained a final inspection approval, or temporary or permanent certificate of occupancy from
the applicable local governing authority for the Premises. Notwithstanding the foregoing, in the event of Tenant Delay (as defined below), Substantial Completion shall be deemed to be the date Substantial Completion would have occurred but for
Tenant Delays. Landlord shall have no obligation to expend any funds, employ any additional labor, contract for overtime work, or otherwise take any action to compensate for any Tenant Delay. Tenant shall reimburse Landlord for any reasonable,
incremental costs in labor, materials, and supplies incurred due to Tenant Delay. If issuance of governmental permits or approvals is conditioned upon Tenant’s installation of its equipment, racking, cabling, or furniture or completion of any
other work or activity in the Premises for which Tenant is responsible, and the governmental authority will not issue such permits or approvals, or schedule an inspection of the Leasehold Improvements due to Tenant’s failure to complete any
work, installation, or activity (including the installation of any telephone, telephone switching, telephone, data, and security cabling and systems, furniture, computers, servers, Tenant’s trade fixtures and other personal property installed
(or to be installed) by or on behalf of Tenant in the Premises), then Substantial Completion is deemed to have occurred without Landlord having obtained such permits or approvals. “Tenant Delay” means any delay in Substantial
Completion caused by Tenant or any Tenant Agent, including without limitation: (i) Tenant’s failure to provide any reasonably requested information or approvals related to the Leasehold Improvements within 3 business days after receipt of
Landlord’s written request therefor; (ii) Tenant’s request for materials, finishes, or installations other than Landlord’s Building standard (unless set forth on the Scope of Work); and (iii) the performance or completion of
any work, labor, or services by Tenant or any Tenant Agent that unreasonably interferes with the performance of the Leasehold Improvements. Tenant shall reimburse Landlord for any reasonable, incremental costs in labor, materials, and supplies
incurred due to Tenant Delay. 
 3. Prior to delivery of possession of the Premises to Tenant, Landlord or Landlord’s architect will
prepare a preliminary punch list in writing for Landlord’s and Tenant’s review, and Landlord and Tenant will examine the Premises and agree on a final punch list that specifies any items of work that require correction, repair, or
replacement (“Punch List”). Tenant must approve the Punch List in writing within two (2) business days of the walkthrough. Landlord will use commercially reasonable efforts to complete the Punch List work within thirty
(30) days. 

  
 C-1 

 4. Except as may be otherwise set forth in the Scope of Work, Tenant is solely responsible
for the purchase and installation of all furniture and equipment, including without limitation its data/telecommunication systems and wiring at the Premises. Subject to Landlord’s reasonable approval, Tenant may use the vendor of its choice for
such installation. Tenant must contact the municipality in which the Building is located for specific installation requirements, comply with all local rules and regulations, and obtain and pay for any and all required permits in connection
therewith. 
 5. Tenant will have reasonable access to the Premises (“Early Access”) during completion of the Leasehold
Improvements to coordinate installation of Tenant’s cabling and wiring and during the thirty (30)-day period immediately prior to Substantial Completion to install its furniture, fixtures, and equipment; provided in any such case
Tenant’s Early Access does not interfere with, or delay completion of, the Leasehold Improvements, and Tenant first provides Landlord with a certificate of insurance as required under the Lease. All insurance, waiver, and indemnity provisions
of the Lease will be in full force and effect during Early Access. Tenant must ensure that its phone/data, security, and other vendors comply with all applicable Laws and pull their permits and perform their work in conjunction with the Leasehold
Improvements so as not to delay completion of the Leasehold Improvements and any and all inspections therefor. Any delay resulting from Early Access, including without limitation due to a Tenant vendor’s work delaying Landlord’s ability to
obtain its permits, is deemed a Tenant Delay. 
 6. Tenant shall be solely responsible for all costs of Tenant Work (“Tenant
Improvement Costs”), including without limitation the professional fees of any engineers, consultants, architects, and/or space planners engaged by Landlord and other professionals preparing and/or reviewing Exhibit C-2 and all
costs in the permitting, demolition, construction, acquisition, and installation of Tenant Work, including, without limitation, contractor fees, overhead, and profit, and the cost of all labor and materials supplied by the general contractor engaged
by Landlord, suppliers, independent contractors, and subcontractors arising in connection with Tenant Work; provided, however, in no event shall any supervisory or construction management fees by Landlord be included as part of the
Tenant Improvement Costs. Tenant shall pay Tenant Improvement Costs to Landlord within thirty (30) days after receipt of an invoice therefor from time to time, provided Landlord shall have the right to invoice Tenant with respect to particular
components of Tenant Work and the applicable amount of Tenant Improvement Costs (as reasonably determined by Landlord) upon substantial completion of such component. If Tenant fails to make any payment when due under this Exhibit, such failure shall
be deemed a failure to make a Rent payment under the Lease. 
 7. Landlord shall obtain from its contractor a commercially customary one-year
warranty for the Leasehold Improvements, and Landlord shall use commercially reasonable efforts to make a claim under such warranties on behalf of Tenant to the extent necessary. 

  
 C-2 

 EXHIBIT E 

RULES AND REGULATIONS 
  

	1.	 Sidewalks, entrances, passages, elevators, vestibules, stairways, corridors, halls, lobby, and any other part
of the Building shall not be obstructed or encumbered by Tenant or used for any purpose other than ingress or egress to and from the Premises. Landlord shall have the right to control and operate the common portions of the Building and exterior
facilities furnished for common use of the Building’s tenants (such as the eating, smoking, and parking areas) in such a manner as Landlord deems appropriate. 

 

	2.	 No awnings or other projections may be attached to the outside walls of the Building without the prior written
consent of Landlord. All drapes and window blinds shall be of a quality, type, design, and color, and attached in a manner approved in writing by Landlord. 

  

	3.	 No showcases, display cases, or other articles may be put in front of or affixed to any part of the exterior of
the Building, or placed in hallways or vestibules without the prior written consent of Landlord. All supplies shall be kept in designated storage areas. Tenant shall not use or permit the use of any portion of the Project for outdoor storage. No
mats, trash, or other objects may be placed in the public corridors, hallways, stairs, or other common areas of the Building. 

  

	4.	 Restrooms and other plumbing fixtures shall not be used for any purposes other than those for which they were
constructed, and no debris, rubbish, rags, or other substances may be thrown therein. Only standard toilet tissue may be flushed in commodes. All damage resulting from any misuse of these fixtures shall be the responsibility of the tenant who, or
whose employees, agents, visitors, clients, or licensees, caused such damage. Bathing and changing of clothes is permitted only in designated shower/locker facilities, and is not permitted in restrooms. 

 

	5.	 Tenant shall not, without the prior written consent of Landlord, mark, paint, drill into, bore, cut, string
wires, or in any way deface any part of the Premises or the Building except for the reasonable hanging of decorative or instructional materials on the walls of the Premises. Tenant shall remove seasonal decorations that are visible outside of the
Premises within 30 days after the end of the applicable season. 

  

	6.	 Tenant shall not construct, install, maintain, use, or operate in any part of the Project any electrical
device, wiring, or other apparatus in connection with a loud speaker system or other sound/communication system that may be heard outside the Premises. 

  

	7.	 No bicycles, mopeds, skateboards, scooters, or other vehicles may be brought into, used, or kept in or about
the Building or in the common areas of the Project other than in locations specifically designated thereof. No animals or pets of any kind (other than a service animal performing a specified task), including without limitation fish, rodents, and
birds, may be brought into, used, or kept in or about the Building. Rollerblading and roller skating is not permitted in the Building or in the common areas of the Project. 

  
 E-1 

	8.	 Tenant shall not cause or permit any unusual or objectionable odors to be produced upon or permeate from the
Premises. 

  

	9.	 No space in the Project may be used for the manufacture of goods for sale in the ordinary course of business,
or for sale at auction of merchandise, goods, or property of any kind. 

  

	10.	 Tenant shall not make any unseemly or disturbing noises, or disturb or interfere with the occupants of the
Building or neighboring buildings or residences by voice, musical instrument, radio, talking machines, whistling, singing, lewd behavior, or in any other way. All passage through the Building’s hallways, elevators, and main lobby shall be
conducted in a quiet, businesslike manner. Tenant shall not commit or suffer any waste upon the Premises, the Building, or the Project, or any nuisance, or do any other act or thing that may disturb the quiet enjoyment of any other tenant in the
Building or Project. 

  

	11.	 Tenant shall not throw anything out of the doors, windows, or down corridors or stairs of the Building

  

	12.	 Tenant shall not place, install, or operate in the Premises or in any part of the Project, any engine, stove,
machinery, or electrical equipment not directly related to its business, including without limitation space heaters, coffee cup warmers, and small refrigerators, conduct mechanical operations, cook thereon or therein, or place or use in or about the
Premises or the Project any explosives, gasoline, kerosene oil, acids, caustics, canned heat, charcoal, or any other flammable, explosive or hazardous material, without the prior written consent of Landlord. Notwithstanding the foregoing, Tenant
shall have the right to install and use a coffee machine, microwave oven, toaster, ice maker, refrigerator, and/or vending machine in compliance with all applicable Laws in a kitchen or break room designated as such by Landlord, provided Tenant
shall use only stainless steel braided hoses. All supply waterlines shall be of copper (not plastic) tubing. 

  

	13.	 No smoking (including without limitation of cigarettes, cigars, and e-cigarettes) is permitted anywhere in the
Premises, the Building, or the Project, including but not limited to restrooms, hallways, elevators, stairs, lobby, exit and entrance vestibules, sidewalks, and parking lot areas, provided smoking shall be permitted in any Landlord-designated
exterior smoking area. All cigarette ashes and butts shall be deposited in the containers provided for such disposal, and shall not be disposed of on sidewalks, parking lot areas, or toilets. 

 

	14.	 Tenant shall not install any additional locks or bolts of any kind upon any door or window of the Building
without the prior written consent of Landlord. Tenant shall, upon the termination of its tenancy, return to Landlord all keys for the Premises, either furnished to or otherwise procured by Tenant, and all security access cards to the Building.

  

	15.	 Tenant shall keep all doors to hallways and corridors closed during Business Hours except as they may be used
for ingress or egress. 

  
 E-2 

	16.	 Tenant shall not use the name of the Building, Project, Landlord, or Landlord’s agents or affiliates in
any way in connection with its business except as the address thereof. Landlord shall also have the right to prohibit any advertising by Tenant that, in Landlord’s sole opinion, tends to impair the reputation of the Building or its desirability
as a building for offices, and upon written notice from Landlord, Tenant shall refrain from or discontinue such advertising. 

  

	17.	 Tenant shall be responsible for all security access cards issued to it, and shall secure the return of all
security cards from all employees terminating employment with them. Lost cards shall cost $35.00 per card to replace. No person/company other than Building tenants and/or their employees may have security access cards unless Landlord grants prior
written approval. 

  

	18.	 All deliveries to the Building that involve the use of a hand cart, hand truck, or other heavy equipment or
device shall be made via the freight elevator, if such freight elevator exists in the Building. Tenant shall be responsible to Landlord for any loss or damage resulting from any deliveries made by or for Tenant to the Building. Tenant shall procure
and deliver to Landlord a certificate of insurance from its movers, which certificate shall name Landlord as an additional insured. 

  

	19.	 Landlord reserves the right to inspect all freight to be brought into the Building, and to exclude from the
Building all freight or other material that violates any of these rules and regulations. 

  

	20.	 Tenant shall refer all contractors, contractor’s representatives, and installation technicians rendering
any service on or to the Premises, to Landlord for Landlord’s approval and supervision before performance of any contractual service or access to Building. This provision shall apply to all work performed in the Building including installation
of telephones, telegraph equipment, electrical devices and attachments, and installations of any nature affecting floors, walls, woodwork, trim, windows, ceilings, equipment, or any other physical portion of the Building. Landlord reserves the right
to require that all agents of contractors and vendors sign in and out of the Building. 

  

	21.	 If Tenant desires to introduce electrical, signaling, telegraphic, telephonic, protective alarm or other wires,
apparatus or devices, Landlord shall direct where and how the same are to be placed, and except as so directed, no installation boring or cutting shall be permitted, without Landlord’s consent, not to be unreasonably withheld, conditioned, or
delayed. Landlord shall have the right to prevent and to cut off the transmission of excessive or dangerous current of electricity or annoyances into or through the Building or the Premises and to require the changing of wiring connections or layout
at Tenant’s expense, to the extent that Landlord may reasonably deem necessary, and further to require compliance with such reasonable and uniformly applied rules as Landlord may establish relating thereto, and in the event of non-compliance
with the requirements or rules, Landlord shall have the right immediately to cut wiring or to do what it reasonably considers necessary to remove the danger, annoyance, or electrical interference with apparatus in any part of the Building. All wires
installed by Tenant must be clearly tagged at the distributing boards and junction boxes and elsewhere where required by Landlord, with the suite number of the office to which such wires lead, and the purpose for which the wires respectively are
used, together with the name of the concern, if any, operating such wires. 

  
 E-3 

	22.	 Landlord reserves the right to exclude from the Building at all times any person who is not known or does not
properly identify himself or herself to Landlord’s management or security personnel. 

  

	23.	 Landlord may require, at its sole option, all persons entering the Building outside of Business Hours to
register at the time they enter and at the time they leave the Building 

  

	24.	 No space within the Building or in the common areas such as the parking lot, may be used at any time for the
purpose of lodging, sleeping or for any immoral or illegal purposes. 

  

	25.	 Tenant shall not use the hallways, stairs, lobby, or other common areas of the Building as lounging areas
during breaks or during lunch periods. 

  

	26.	 No canvassing soliciting, or peddling is permitted in the Building or its common areas. 

 

	27.	 Tenant shall comply with all Laws regarding the collection, sorting separation, and recycling of garbage,
trash, rubbish and other refuse, and Landlord’s recycling policy for die Building. 

  

	28.	 Landlord does not maintain suite finishes that are non-standard, such as kitchens, bathrooms, wallpaper,
special lights, etc. However, should the need arise for repair of items not maintained by Landlord, Landlord at its sole option, may arrange for the work to be done at tenant’s expense. 

 

	29.	 Tenant shall clean at least once a year, at its expense, drapes in the Premises that are visible from the
exterior of the Building. 

  

	30.	 No pictures, signage, advertising decals, banners, etc. may be placed in or on windows in such a manner as they
are visible from the exterior, without the prior written consent of Landlord. 

  

	31.	 Tenant is prohibited at all times from eating or drinking in hallways, elevators, restrooms, lobbies, or lobby
vestibules outside of the Premises. Food storage shall be limited to a Landlord-approved kitchen or break room. 

  

	32.	 Tenant shall be responsible to Landlord for any acts of vandalism performed in the Building by its employees,
invitees, agents, contractors, licensees, subtenants, and assignees. 

  

	33.	 Tenant shall not permit the visit to the Premises of persons in such numbers or under such conditions as to
interfere with the use and enjoyment by other tenants of the entrances, hallways, elevators, lobby, exterior common areas, or other public portions or facilities of the Building. 

  
 E-4 

	34.	 Landlord’s employees shall not perform any work or do anything outside of their regular duties unless
under special instructions from Landlord. Requests for such requirements shall be submitted in writing to Landlord. 

  

	35.	 Tenant is prohibited from interfering in any manner with the installation and/or maintenance of the heating air
conditioning and ventilation facilities and equipment at the Project. 

  

	36.	 Landlord shall not be responsible for lost or stolen personal property, equipment, money, or jewelry regardless
of whether such loss occurs when an area is locked against entry or not. 

  

	37.	 Landlord shall not permit entrance to the Premises by use of pass key controlled by Landlord, to any person at
any time without written permission of Tenant, except employees, contractors or service personnel supervised or employed by Landlord. 

  

	38.	 Tenant shall observe and comply with the driving and parking signs and markers on the Project grounds and
surrounding areas. Tenant shall comply with all reasonable and uniformly applied parking regulations promulgated by Landlord from time to time for the orderly use of vehicle parking areas. Parked vehicles shall not be used for vending or any other
business or other activity while parked in the parking areas. Vehicles shall be parked only in striped parking spaces, except for loading and unloading, which shall occur solely in zones marked for such purpose, and be so conducted as to not
unreasonably interfere with traffic flow or with loading and unloading areas of other tenants. Tractor trailers shall be parked in areas designated for tractor trailer parking. Employee and tenant vehicles shall not be parked in spaces marked for
visitor parking or other specific use. All vehicles entering or parking in the parking areas shall do so at owner’s sole risk and Landlord assumes no responsibility for any damage, destruction, vandalism, or theft. Tenant shall cooperate with
Landlord in any reasonable and uniformly applied measures implemented by Landlord to control abuse of the parking areas, including without limitation access control programs, tenant and guest vehicle identification programs, and validated parking
programs, provided no such validated parking program shall result in Tenant being charged for spaces to which it has a right to free use under the Lease. Each vehicle owner shall promptly respond to any sounding vehicle alarm or horn, and failure to
do so may result in temporary or permanent exclusion of such vehicle from the parking areas. Any vehicle that violates the parking regulations may be cited, towed at the expense of the owner, temporarily or permanently excluded from the parking
areas, or subject to other lawful consequence. 

  

	39.	 Tenant shall not enter other separate tenants’ hallways, restrooms, or premises except with prior written
approval from Landlord’s management. 

  

	40.	 Tenant shall not place weights anywhere beyond the load-per-square-foot carrying capacity of the Building.

  

	41.	 Tenant shall comply with all laws, regulations, or other governmental requirements with respect to energy
savings, not permit any waste of any utility services provided Landlord, and cooperate with Landlord fully to ensure the most effective and efficient operation of the Building. 

  
 E-5 

	42.	 The finishes, including floor and wall coverings, and the furnishings and fixtures in any areas of the Premises
that are visible from the common areas of the Building are subject to Landlord’s approval in its sole discretion Selections for these areas shall be pre-approved in writing by Landlord. 

 

	43.	 Power strips and extension cords shall not be combined (also known as daisy chaining). 

 

	44.	 Candles and open flames are prohibited in the Building. 

 

	45.	 Guns, firearms, and other dangerous weapons (concealed or otherwise) are not allowed at the Project, subject to
applicable Law (if any) requiring Landlord to so permit at the Project. 

 Landlord reserves the right to rescind any of these rules and
make such other and further rules and regulations as in the judgment of Landlord shall from time to time be needed for the safety, protection, care, and cleanliness of the Project, the operations thereof, the preservation of good order therein, and
the protection and comfort of its tenants, their agents, employees, and invitees, which rules when made and notice thereof given to Tenant shall be binding upon Tenant in a like manner as if originally prescribed. As used in these rules and
regulations, capitalized terms shall have the respective meanings given to them in the Lease to which these rules and regulations are attached, provided Tenant shall be responsible for compliance herewith by everyone under Tenant’s reasonable
control, including without limitation its employees, invitees, agents, contractors, licensees, subtenants and assignees, and a violation of these rules and regulations by any of the foregoing is deemed a violation by Tenant. 

  
 E-6

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