Document:

EX-10.8

 Exhibit 10.8 

EXECUTIVE EMPLOYMENT AGREEMENT 

This Executive Employment Agreement (this “Agreement”) is made and entered into this 20th day of October, 2017 (the “Effective
Date”) by and between Spero Therapeutics, Inc., a Delaware corporation (“Company”), and Cristina Larkin (“Executive”). 

WHEREAS, Executive is currently employed by Company as its Chief Operating Officer, pursuant to the terms of that certain offer letter
dated February 23, 2016 (the “Offer Letter”); 
 WHEREAS, Executive and Company desire to enter into a formal
employment agreement to assure the harmonious performance of the affairs of Company and which sets forth the current terms of Executive’s employment by Company as well as to enter into a Proprietary Information and Inventions Assignment
Agreement (the “Restrictive Covenant Agreement”). 
 NOW, THEREFORE, in consideration of the mutual promises, terms,
provisions, and conditions contained herein, Company and Executive hereby agree to amend and restate the Offer Letter as follows:  

1. Roles and Duties. Subject to the terms and conditions of this Agreement, Company shall employ Executive as its Chief Operating
Officer reporting to Company’s Chief Executive Officer (“CEO”). The Executive shall have such duties and responsibilities as are reasonably determined by the Board of Directors and are consistent with the duties customarily performed
by a Chief Operating Officer of a similarly situated company in the United States. Executive accepts such employment upon the terms and conditions set forth herein, and agrees to perform such duties and discharge such responsibilities to the best of
Executive’s ability. During Executive’s employment, Executive shall devote all of Executive’s business time and energies to the business and affairs of Company. Notwithstanding the foregoing, nothing herein shall preclude Executive
from (i) performing services for such other companies as Company may designate or permit; (ii) serving, with the prior written consent of the Board, which consent shall not be unreasonably withheld, as a member of the boards of directors
or advisory boards (or their equivalents in the case of a non-corporate entity) of non-competing businesses or charitable, educational or civic organizations; (iii) engaging in charitable activities and community affairs; and (iv) managing
Executive’s personal investments and affairs; provided, however, that the activities set out in clauses (i), (ii), (iii) and (iv) shall be limited by Executive so as not to materially interfere, individually or in the aggregate, with
the performance of Executive’s duties and responsibilities hereunder. 
  

	 	2.	Term of Employment. 

 (a) Term. Subject to the terms hereof, Executive’s
employment hereunder shall continue until terminated hereunder by either party (such term of employment referred to herein as the “Term”). 

(b) Termination. Notwithstanding anything else contained in this Agreement, Executive’s employment hereunder shall terminate upon
the earliest to occur of the following: 
 (i) Death. Immediately upon Executive’s death; 

  

 (ii) Termination by Company. 

(A) If because of Executive’s Disability (as defined below in Section 2(c)), written notice by Company to Executive
that Executive’s employment is being terminated as a result of Executive’s Disability, which termination shall be effective on the date of such notice or such later date as specified in writing by Company; 

(B) If for Cause (as defined below in Section 2(d)), written notice by Company to Executive that Executive’s
employment is being terminated for Cause, which termination shall be effective on the date of such notice or such later date as specified in writing by Company, provided that if prior to the effective date of such termination Executive has
cured the circumstances giving rise to the Cause (if capable of being cured as provided in Section 2(d)), then such termination shall not be effective; or 

(C) If by Company for reasons other than under Sections 2(b)(ii)(A) or (B), written notice by Company to Executive that
Executive’s employment is being terminated, which termination shall be effective thirty (30) days after the date of such notice. 

(iii) Termination by Executive. 

(A) If for Good Reason (as defined below in Section 2(e)), written notice by Executive to Company that Executive is
terminating Executive’s employment for Good Reason and that sets forth the factual basis supporting the alleged Good Reason, which termination shall be effective thirty (30) days after the date of such notice; provided that if prior
to the effective date of such termination Company has cured the circumstances giving rise to the Good Reason if capable of being cured as provided in Section 2(e), then such termination shall not be effective; or 

(B) If without Good Reason, written notice by Executive to Company that Executive is terminating Executive’s employment,
which termination shall be effective no fewer than sixty (60) days after the date of such notice unless waived, in whole or in part, by Company. 

Notwithstanding anything in this Section 2(b), Company may at any point, under the conditions set forth in Section 2(b)(ii)(B),
terminate Executive’s employment for Cause prior to the effective date of any other termination contemplated hereunder; provided that if prior to the effective date of such for-Cause termination Executive has cured the circumstances
giving rise to the Cause (if capable of being cured as provided in Section 2(d)), then such termination shall not be effective. 
 (c)
Definition of “Disability”. For purposes of this Agreement, “Disability” shall mean Executive’s incapacity or inability to perform Executive’s duties and responsibilities as contemplated herein by reason of a
medically determinable mental or physical impairment for one hundred twenty (120) days or more within any one (1) year period (cumulative or consecutive), 

  
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which impairment can reasonably be expected to result in death or can be expected to last for a continuous period of not less than six (6) months. The determination that Executive is
disabled hereunder, if disputed by the parties, shall be resolved by a physician reasonably satisfactory to Executive and Company, at Company’s expense, and the determination of such physician shall be final and binding upon both Executive and
Company. Executive hereby consents to such examination and consultation by a physician. Company will keep all information it receives as a result of such inquiry and determination confidential and will not use it for any purpose other than in
connection with exercising its rights under this Agreement. 
 (d) Definition of “Cause”. As used herein, “Cause”
shall mean: (i) Executive’s conviction of (A) a felony or (B) any misdemeanor involving moral turpitude, deceit, dishonesty or fraud; (ii) Executive’s willful failure or refusal to comply with lawful directions of the
CEO, which failure or refusal continues for more than thirty (30) days after written notice is given to Executive by the CEO, which notice sets forth in reasonable detail the nature of such failure or refusal; (iii) willful and material
breach by Executive of a written Company policy applicable to Executive or Executive’s covenants and/or obligations under this Agreement or the material breach of the Restrictive Covenant Agreement; and/or (iv) material misconduct by
Executive that seriously discredits or damages Company or any of its affiliates. Notwithstanding anything to the contrary in the foregoing, Executive shall be permitted to perform substantial portions of her duties on a remote or work-from-home
basis (and Company shall reimburse Executive for Executive’s reasonable out-of-pocket travel, housing, meals and other related expenses associated with commuting to Company’s offices as a result of such arrangement), provided that such
arrangement does not unreasonably impair her ability to perform her obligations under this Agreement, as reasonably determined by the Company, and such remote or work-from-home arrangement shall not constitute “Cause” as defined herein.
Except in the case of (ii) above, it is not necessary that the Company’s finding of Cause occur prior to Executive’s termination of service. If Company determines, subsequent to Executive’s termination of service, that prior to
Executive’s termination Executive engaged in conduct which would constitute “Cause,” (other than pursuant to (ii) above) then Executive shall have no right to any benefit or compensation under this Agreement. 

(e) Definition of “Good Reason”. As used herein, “Good Reason” shall mean: (i) relocation of Executive’s
principal business location to a location more than thirty (30) miles from Executive’s then-current business location; (ii) a material diminution in Executive’s duties, authority or responsibilities; (iii) a material
reduction in Executive’s Base Salary; or (iv) willful and material breach by Company of its covenants and/or obligations under this Agreement; provided that, in each of the foregoing clauses (i) through (iv) (A) Executive
provides Company with written notice that Executive intends to terminate Executive’s employment hereunder for one of the grounds set forth in this Section 2(e) within thirty (30) days of such ground occurring, (B) if such ground
is capable of being cured, Company has failed to cure such ground within a period of thirty (30) days from the date of such written notice, and (C) Executive terminates by written notice Executive’s employment within sixty-five
(65) days from the date that Executive provides the notice contemplated by clause (A) of this Section 2(e). For purposes of clarification, the above-listed conditions shall apply separately to each occurrence of Good Reason, and
failure to adhere to such conditions in the event of Good Reason shall not disqualify Executive from asserting Good Reason for any subsequent occurrence of Good Reason. In addition, Executive may terminate his or her employment for Good Reason
within one (1) year following a Change of Control (as defined below) if, after the Change of Control, Executive is not an executive of the parent company, provided that Executive’s roles, responsibilities and scope of authority within the
subsidiary is not comparable to Executive’s roles, responsibilities and scope of authority with 

  
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Company prior to the Change of Control. For purposes of this Agreement, “Good Reason” shall be interpreted in a manner, and limited to the extent necessary, so that it shall not cause
adverse tax consequences for either party with respect to Section 409A (“Section 409A”) of the Internal Revenue Code of 1986, as amended (the “Code”) and any successor statute, regulation and guidance thereto. 

 

	 	3.	Compensation. 

 (a) Base Salary. Company shall pay Executive a base salary (the
“Base Salary”) at the annual rate of Three Hundred Forty-Five Thousand Dollars ($345,000). The Base Salary shall be payable in substantially equal periodic installments in accordance with Company’s payroll practices as in effect from
time to time. Company shall deduct from each such installment all amounts required to be deducted or withheld under applicable law or under any employee benefit plan in which Executive participates. The Board or an appropriate committee thereof
shall, on an annual basis, review the Base Salary, which may be adjusted upward (but not downward) at Company’s discretion. 
 (b)
Annual Performance Bonus. Executive shall be eligible to receive an annual cash bonus (the “Annual Performance Bonus”), with the target amount of such Annual Performance Bonus equal to thirty percent (30%) of Executive’s
Base Salary in the year to which the Annual Performance Bonus relates; provided that the actual amount of the Annual Performance Bonus may be greater or less than such target amount. The amount of the Annual Performance Bonus shall be
determined by the Board of Directors or an appropriate committee thereof in its sole discretion, and shall be paid to Executive no later than March 15th of the calendar year immediately
following the calendar year in which it was earned. Except as provided in Section 4, Executive must be employed by Company on the last day of the applicable fiscal year to which the Annual Performance Bonus relates in order to be eligible for,
and to be deemed as having earned, such Annual Performance Bonus. Company shall deduct from the Annual Performance Bonus all amounts required to be deducted or withheld under applicable law or under any employee benefit plan in which Executive
participates. 
 (c) Equity. In addition to the equity awards currently outstanding, Executive will be eligible to be considered for
the grant of stock options and/or other equity-based awards commensurate with Executive’s position and responsibilities. The amount, terms and conditions of any stock option or other equity-based award will be determined by the Board of
Directors or an appropriate committee thereof in its discretion and set forth in the applicable equity plan and other documents governing the award. 

(d) Paid Time Off. In addition to standard paid holidays, Executive may take up to twenty (20) days of paid time off
(“PTO”) per year, to be scheduled so as not to materially disrupt Company’s operations, pursuant to the terms and conditions of Company policy and practices as applied to Company senior executives. 

(e) Fringe Benefits. Executive shall be entitled to participate in all benefit/welfare plans and fringe benefits provided to Company
senior executives. Executive understands that, except when prohibited by applicable law, Company’s benefit plans and fringe benefits may be amended by Company from time to time in its sole discretion. The terms of any such benefits shall be
governed by the applicable plan documents and Company policies in effect from time to time. 

  
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 (f) Reimbursement of Expenses. Company shall reimburse Executive for all ordinary and
reasonable out-of-pocket business expenses incurred by Executive in furtherance of Company’s business in accordance with Company’s policies with respect thereto as in effect from time to time. Executive must submit any request for
reimbursement no later than ninety (90) days following the date that such business expense is incurred. All reimbursements provided under this Agreement shall be made or provided in accordance with the requirements of Section 409A
including, where applicable, the requirement that (i) any reimbursement is for expenses incurred during Executive’s lifetime (or during a shorter period of time specified in this Agreement); (ii) the amount of expenses eligible for
reimbursement during a calendar year may not affect the expenses eligible for reimbursement in any other calendar year; (iii) the reimbursement of an eligible expense shall be made no later than the last day of the calendar year following the
year in which the expense is incurred; and (iv) the right to reimbursement or in-kind benefits is not subject to liquidation or exchange for another benefit. 

(g) Indemnification. Executive shall be entitled to indemnification with respect to Executive’s services provided hereunder
pursuant to Delaware law, the terms and conditions of Company’s certificate of incorporation and/or by-laws, and Company’s standard indemnification agreement for directors and officers as executed by Company and Executive. Executive shall
be entitled to coverage under the Company’s Directors’ and Officers’ (“D&O”) insurance policies that it may hold now or in the future to the same extent and in the same manner (i.e., subject to the same terms and
conditions) that the Company’s other executive officers are entitled to coverage under any of the Company’s D&O insurance policies that it may have. 

(h) Forfeiture/Clawback. All compensation shall be subject to any forfeiture or clawback policy established by Company generally for
senior executives from time to time and any other such policy required by applicable law. 
  

	 	4.	Payments Upon Termination. 

 (a) Definition of Accrued Obligations. For purposes
of this Agreement, “Accrued Obligations” means: (i) the portion of Executive’s Base Salary that has accrued prior to any termination of Executive’s employment with Company and has not yet been paid; (ii) any accrued but
unused PTO pursuant to Company’s standard policy and practices; and (iii) the amount of any expenses properly incurred by Executive on behalf of Company prior to any such termination and not yet reimbursed. Executive’s entitlement to
any other compensation or benefit under any plan of Company shall be governed by and determined in accordance with the terms of such plans, except as otherwise specified in this Agreement. 

(b) Termination by Company for Cause. If Executive’s employment hereunder is terminated by Company for Cause, then Company shall
pay the Accrued Obligations to Executive promptly following the effective date of such termination and shall have no further obligations with respect to any benefit or compensation under this Agreement to Executive hereunder. 

  
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 (c) Termination by Executive Without Good Reason. If Executive’s employment hereunder
is terminated by Executive without Good Reason, then Company shall pay the Accrued Obligations and any accrued and unpaid Annual Performance Bonus for the prior fiscal year to Executive promptly following the effective date of such termination and
shall have no further obligations with respect to any benefit or compensation under this Agreement to Executive hereunder. 
 (d)
Termination as a Result of Executive’s Disability or Death. If Executive’s employment hereunder terminates as a result of Executive’s Disability or death, promptly after such termination Company shall pay to Executive
(i) the Accrued Obligations; (ii) any accrued and unpaid Annual Performance Bonus for the prior fiscal year; and (iii) the Pro Rated Bonus (as defined below) and, shall have no further obligations with respect to any benefit or
compensation under this Agreement to Executive hereunder. As used in this Section 4, “Pro Rated Bonus” shall mean an amount in cash equal to the target of Annual Performance Bonus for which Executive would have been eligible with
respect to the year in which termination of Executive’s employment occurs multiplied by a fraction, the numerator of which is the number of days during which Executive is employed by Company during the year of termination and the denominator of
which is 365. 
 (e) Termination by Company Without Cause or by Executive For Good Reason. In the event that Executive’s
employment is terminated by action of Company other than for Cause, or Executive terminates Executive’s employment for Good Reason, then, in addition to the Accrued Obligations and any accrued and unpaid Annual Performance Bonus for the prior
fiscal year, Executive shall receive the following, subject to the terms and conditions described in Section 4(g) (including Executive’s execution of the Release (as defined herein)): 

(i) Severance Payments. Continuation of payments in an amount equal to Executive’s then-current Base Salary for a
nine (9) month period, less all customary and required taxes and employment-related deductions, in accordance with Company’s normal payroll practices (provided such payments shall be made at least monthly), commencing on the first payroll
date following the date on which the Release required by Section 4(g) becomes effective and non-revocable, but not after seventy (70) days following the effective date of termination from employment; provided, that if the 70th day falls in the calendar year following the year during which the termination or separation from service occurred, then the payments will commence in such subsequent calendar year; provided further
that if such payments commence in such subsequent year, the first such payment shall be a lump sum in an amount equal to the payments that would have come due since Employee’s separation from service. 

(ii) Pro Rata Bonus. Payment of the Pro Rated Bonus, paid to Executive no later than March 15 of the calendar year
next preceding the year of termination of employment, after deduction of all amounts required to be deducted or withheld under applicable law. 

  
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 (iii) Benefits Payments. Upon completion of appropriate forms and subject
to applicable terms and conditions under the Consolidated Omnibus Budget Reconciliation Act of 1985, as amended (“COBRA”), Company shall continue to provide Executive medical insurance coverage to the same extent that such insurance
continues to be provided to similarly situated executives at the time of Executive’s termination with the cost of the regular premium for such benefits shared in the same relative proportion by Company and Executive as in effect on the last day
of employment (the “COBRA Payment”), until the earlier to occur of: (i) twelve (12) months following Executive’s termination date, or (ii) the date Executive becomes eligible for medical benefits with another employer.
Notwithstanding the foregoing, if Executive’s COBRA Payment would cause the applicable group health plan to be discriminatory and, therefore, result in adverse tax consequences to Executive, Company shall, in lieu of the COBRA Payment, provide
Executive with an equivalent monthly cash payment, minus deduction of all amounts required to be deducted or withheld under applicable law, for any period of time Executive is eligible to receive the COBRA Payment. Executive shall bear full
responsibility for applying for COBRA continuation coverage and Company shall have no obligation to provide Executive such coverage if Executive fails to elect COBRA benefits in a timely fashion. 

Payment of the above described severance payments and benefits are expressly conditioned on Executive’s execution without revocation of
the Release and return of Company property under Section 6. 
 (f) Termination by Company Without Cause or by Executive For Good
Reason Following a Change of Control. In the event that a Change of Control (as defined below) occurs and within a period of one (1) year following the Change of Control, or ninety (90) days preceding the earlier to occur of a Change
of Control or the execution of a definitive agreement the consummation of which would result in a Change of Control, Executive’s employment is terminated other than for Cause, or Executive terminates Executive’s employment for Good Reason,
then, in addition to the Accrued Obligations and any accrued and unpaid Annual Performance Bonus for the prior fiscal year, Executive shall receive the following, subject to the terms and conditions described in Section 4(g) (including
Executive’s execution of the Release): 
 (i) Lump Sum Severance Payment. Payment of a lump sum amount equal to
twelve (12) months of Executive’s then-current Base Salary plus the Pro Rated Bonus, less all customary and required taxes and employment-related deductions, paid on the first payroll date following the date on which the Release required
by Paragraph 4(g) becomes effective and non-revocable, but not after seventy (70) days following the effective date of termination from employment. 

(ii) Equity Acceleration. (A) All of Executive’s unvested equity awards will accelerate and vest immediately
on the date of termination of Executive’s employment if such employment commenced at least twenty-four (24) months prior to a Change of Control, (B) 50% of Executive’s unvested equity awards will vest immediately on the date of
termination of Executive’s employment if such employment commenced fewer than twenty-four (24) months but at least twelve (12) months prior to a Change of Control, and (C) 25% of Executive’s unvested equity awards will vest
immediately on the date of termination of Executive’s employment if such employment commenced fewer than twelve (12) months prior to a Change of Control. 

  
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 (iii) Benefit Payments. Upon completion of appropriate forms and subject
to applicable terms and conditions under COBRA, Company shall continue to provide Executive medical insurance coverage to the same extent that such insurance continues to be provided to similarly situated executives at the time of Executive’s
termination with the cost of the regular premium for such benefits shared in the same relative proportion by Company and Executive as in effect on the last day of employment, until the earlier to occur of: (i) twelve (12) months following
Executive’s termination date, or (ii) the date Executive becomes eligible for medical benefits with another employer. Notwithstanding the foregoing, if Executive’s COBRA Payment would cause the applicable group health plan to be
discriminatory and, therefore, result in adverse tax consequences to Executive, Company shall, in lieu of the COBRA Payment, provide Executive with an equivalent monthly cash payment, minus deduction of all amounts required to be deducted or
withheld under applicable law, for any period of time Executive is eligible to receive the COBRA Payment. Executive shall bear full responsibility for applying for COBRA continuation coverage and Company shall have no obligation to provide Executive
such coverage if Executive fails to elect COBRA benefits in a timely fashion. 
 Payment of the above described severance payments and
benefits are expressly conditioned on Executive’s execution without revocation of the Release and return of Company property under Section 6. In the event that Executive is eligible for the severance payments and benefits under this
Section 4(f), Executive shall not be eligible for any of the severance payments and benefits as provided in Section 4(e). 
 As
used herein, a “Change of Control” shall mean the occurrence of any of the following events: (i) Ownership. Any “Person” (as such term is used in Sections 13(d) and 14(d) of the Securities Exchange Act of 1934, as
amended) becomes the “Beneficial Owner” (as defined in Rule 13d-3 under said Act), directly or indirectly, of securities of Company representing fifty percent (50%) or more of the total voting power represented by Company’s then
outstanding voting securities (excluding for this purpose any such voting securities held by Company, or any affiliate, parent or subsidiary of Company, or by any employee benefit plan of Company) pursuant to a transaction or a series of related
transactions; or (ii) Merger/Sale of Assets. (A) A merger or consolidation of Company whether or not approved by the Board, other than a merger or consolidation which would result in the voting securities of Company outstanding
immediately prior thereto continuing to represent (either by remaining outstanding or by being converted into voting securities of the surviving entity or the parent of such corporation) at least fifty percent (50%) of the total voting power
represented by the voting securities of Company or such surviving entity or parent of such corporation, as the case may be, outstanding immediately after such merger or consolidation; (B) or Company’s stockholders approve an agreement for
the sale or disposition by Company of all or substantially all of Company’s assets; or (iii) Change in Board Composition. A change in the composition of the Board, as a result of which fewer than a majority of the directors are
Incumbent Directors. “Incumbent Directors” shall mean directors who either (A) are directors of Company as of the date of this Agreement, or (B) are elected, or nominated for 

  
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election, to the Board with the affirmative votes of at least a majority of the Incumbent Directors, or by a committee of the Board made up of at least a majority of the Incumbent Directors, at
the time of such election or nomination (but shall not include an individual whose election or nomination is in connection with an actual or threatened proxy contest relating to the election of directors). 

(g) Execution of Release of Claims. Company shall not be obligated to pay Executive any of the severance payments or benefits described
in this Section 4 unless and until Executive has executed (without revocation) a release of claims as described below (the “Release”). The Release shall contain reasonable and customary provisions including a general release of claims
against Company and its affiliated entities and each of their officers, directors and employees as well as mutual non-disparagement, confidentiality, cooperation and the like. The Release must be provided to Executive not later than fifteen
(15) days following the effective date of termination of Executive’s employment by Company and executed by Executive and returned to Company within sixty (60) days after such effective date. If Executive fails or refuses to return the
Release within such 60-day period, Executive’s severance payments and benefits to be paid hereunder shall be forfeited. 
 (h) No
Other Payments or Benefits Owing. Except as expressly set forth herein, the payments and benefits set forth in this Section 4: (a) shall be the sole amounts owing to Executive upon termination of Executive’s employment for the
reasons set forth above, and Executive shall not be eligible for any other payments or other forms of compensation or benefits; (b) shall be the sole remedy, if any, available to Executive in the event that Executive brings any claim against
Company relating to the termination of Executive’s employment under this Agreement; and (c) shall not be subject to set-off by Company or any obligation on the part of Executive to mitigate or to offset compensation earned by Executive in
other pursuits after termination of employment, other than as specified herein with respect medical benefits provided by another employer. 

5. Prohibited Competition and Solicitation. Executive expressly acknowledges that: (a) there are competitive and proprietary
aspects of the business of Company; (b) during the course of Executive’s employment, Company shall furnish, disclose or make available to Executive confidential and proprietary information and may provide Executive with unique and
specialized training; (c) such Confidential Information and training have been developed and shall be developed by Company through the expenditure of substantial time, effort and money, and could be used by Executive to compete with Company;
and (d) in the course of Executive’s employment, Executive shall be introduced to customers and others with important relationships to Company, and any and all “goodwill” created through such introductions belongs exclusively to
Company, including, but not limited to, any goodwill created as a result of direct or indirect contacts or relationships between Executive and any customers of Company. In light of the foregoing acknowledgements, and as a condition of continued
employment hereunder, Executive hereby reaffirms, confirms and approves the Proprietary Information and Inventions Assignment Agreement entered into on the date hereof as a binding obligation of the Executive, enforceable in accordance with its
terms. The Executive acknowledges and agrees that any Base Salary and/or Annual Performance Bonus paid to the Executive pursuant to this Agreement shall serve as additional consideration for the Executive’s obligations under the Employee
Non-Competition Agreement, Non-Solicitation, Confidentiality and Assignment Agreement. 

  
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 6. Property and Records. Upon the termination of Executive’s employment hereunder for
any reason or for no reason, or if Company otherwise requests, Executive shall: (a) return to Company all tangible business information and copies thereof (regardless how such Confidential Information or copies are maintained), and
(b) deliver to Company any property of Company which may be in Executive’s possession, including, but not limited to, Blackberry-type devices, smart phones, laptops, cell phones (the foregoing, “electronic devices”), products,
materials, memoranda, notes, records, reports or other documents or photocopies of the same. Executive may retain copies of any exclusively personal data contained in or on Company-owned electronic devices returned to Company pursuant to the
foregoing. The foregoing notwithstanding, Executive understands and agrees that Company property belongs exclusively to Company, it should be used for Company business, and Executive has no reasonable expectation of privacy on any Company property
or with respect to any information stored thereon.  
 7. Cooperation. During and after Executive’s employment, Executive
shall fully cooperate with Company to the extent reasonable in the defense or prosecution of any claims or actions now in existence or which may be brought in the future against or on behalf of Company (other than claims directly or indirectly
against Executive) which relate to events or occurrences that transpired while Executive was employed by Company. Executive’s cooperation in connection with such claims or actions shall include, but not be limited to, being available to meet
with counsel to prepare for discovery or trial and to act as a witness on behalf of Company at mutually convenient times. During and after Executive’s employment, Executive also shall fully cooperate with Company to the extent reasonable in
connection with any investigation or review of any federal, state or local regulatory authority as any such investigation or review relates to events or occurrences that transpired while Executive was employed by Company. Company shall reimburse
Executive for any reasonable out-of-pocket expenses incurred in connection with the Executive’s performance of obligations pursuant to this section. In addition, Company shall compensate Executive on an hourly basis, based on a rate
commensurate with Executive’s Base Salary in effect prior to termination, for time Executive spends in excess of 10 hours in any calendar quarter providing services to the Corporation after termination.  

 

	 	8.	Code Sections 409A and 280G. 

 (a) In the event that the payments or benefits set forth
in Section 4 of this Agreement constitute “non-qualified deferred compensation” subject to Section 409A, then the following conditions apply to such payments or benefits: 

(i) Any termination of Executive’s employment triggering payment of benefits under Section 4 must constitute a
“separation from service” under Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. §1.409A-1(h) before distribution of such benefits can commence. To the extent that the termination of Executive’s employment does not
constitute a separation of service under Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. §1.409A-1(h) (as the result of further services that are reasonably anticipated to be provided by Executive to Company at the time
Executive’s employment terminates), any such payments under Section 4 that constitute deferred compensation under Section 409A shall be delayed until after the date of a subsequent event constituting a separation of service under
Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. §1.409A-1(h). For purposes of clarification, this Section 8(a) shall not cause any forfeiture of benefits on Executive’s part, but shall only act as a delay until such time as
a “separation from service” occurs. 

  
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 (ii) Notwithstanding any other provision with respect to the timing of payments
under Section 4 if, at the time of Executive’s termination, Executive is deemed to be a “specified employee” of Company (within the meaning of Section 409A(a)(2)(B)(i) of the Code), then limited only to the extent necessary
to comply with the requirements of Section 409A, any payments to which Executive may become entitled under Section 4 which are subject to Section 409A (and not otherwise exempt from its application) shall be withheld until the first
(1st) business day of the seventh (7th) month following the termination of Executive’s employment, at which time Executive shall
be paid an aggregate amount equal to the accumulated, but unpaid, payments otherwise due to Executive under the terms of Section 4. 

(b) It is intended that each installment of the payments and benefits provided under Section 4 of this Agreement shall be treated as a
separate “payment” for purposes of Section 409A. Neither Company nor Executive shall have the right to accelerate or defer the delivery of any such payments or benefits except to the extent specifically permitted or required by
Section 409A. 
 (c) Notwithstanding any other provision of this Agreement to the contrary, this Agreement shall be interpreted and at
all times administered in a manner that avoids the inclusion of compensation in income under Section 409A, or the payment of increased taxes, excise taxes or other penalties under Section 409A. The parties intend this Agreement to be in
compliance with Section 409A. Executive acknowledges and agrees that Company does not guarantee the tax treatment or tax consequences associated with any payment or benefit arising under this Agreement, including but not limited to consequences
related to Section 409A. 
 (d) If any payment or benefit Executive would receive under this Agreement, when combined with any other
payment or benefit Executive receives pursuant to a Change of Control (for purposes of this section, a “Payment”) would: (i) constitute a “parachute payment” within the meaning of Section 280G the Code; and
(ii) but for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then such Payment shall be either: (A) the full amount of such Payment; or (B) such lesser amount (with
cash payments being reduced before stock option compensation) as would result in no portion of the Payment being subject to the Excise Tax, whichever of the foregoing amounts, taking into account the applicable federal, state and local employments
taxes, income taxes, and the Excise Tax, results in Executive’s receipt, on an after-tax basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. Notwithstanding the
foregoing, if, prior to the closing of an initial public offering, any Payment can be exempt from the definition of “parachute payment” and the Excise Tax pursuant to the shareholder approval requirements described in Treas. Regs. §
1.280G-1, Q&A 6, the Company will, at the Executive’s election (and subject to the Executive signing an appropriate waiver) seek shareholder approval to exempt such Payment from the definition of “parachute payment” and the Excise
Tax. 

  
 11 

	 	9.	General. 

 (a) Notices. Except as otherwise specifically provided herein, any
notice required or permitted by this Agreement shall be in writing and shall be delivered as follows with notice deemed given as indicated: (i) by personal delivery when delivered personally; (ii) by overnight courier upon written
verification of receipt; (iii) by telecopy or facsimile transmission upon acknowledgment of receipt of electronic transmission; or (iv) by certified or registered mail, return receipt requested, upon verification of receipt. 

Notices to Executive shall be sent to the last known address in Company’s records or such other address as Executive may specify in
writing. 
 Notices to Company shall be sent to: 

Spero Therapeutics, Inc. 
 675
Massachusetts Ave., 14th Floor 
 Cambridge, MA 02139 

Attn: CEO 
 (b) Modifications
and Amendments. The terms and provisions of this Agreement may be modified or amended only by written agreement executed by the parties hereto. 

(c) Waivers and Consents. The terms and provisions of this Agreement may be waived, or consent for the departure therefrom granted, only
by a written document executed by the party entitled to the benefits of such terms or provisions. No such waiver or consent shall be deemed to be or shall constitute a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be effective only in the specific instance and for the purpose for which it was given and shall not constitute a continuing waiver or consent. 

(d) Assignment. Company may assign its rights and obligations hereunder to any person or entity that succeeds to all or substantially
all of Company’s business or that aspect of Company’s business in which Executive is principally involved. Executive may not assign Executive’s rights and obligations under this Agreement without the prior written consent of Company.

 (e) Governing Law/Dispute Resolution. This Agreement and the rights and obligations of the parties hereunder shall be construed in
accordance with and governed by the law of the Commonwealth of Massachusetts without giving effect to the conflict of law principles thereof. Any legal action or proceeding with respect to this Agreement shall be brought in the courts of the
Commonwealth of Massachusetts or of the United States of America for the District of Massachusetts. By execution and delivery of this Agreement, each of the parties hereto accepts for itself and in respect of its property, generally and
unconditionally, the non-exclusive jurisdiction of the aforesaid courts. 
 (f) Jury Waiver. ANY, ACTION, DEMAND, CLAIM, OR
COUNTERCLAIM ARISING UNDER OR RELATING TO THIS AGREEMENT SHALL BE RESOLVED BY A JUDGE ALONE, AND EACH OF COMPANY AND EXECUTIVE WAIVES ANY RIGHT TO A JURY TRIAL THEREOF. 

  
 12 

 (g) Headings and Captions. The headings and captions of the various subdivisions of this
Agreement are for convenience of reference only and shall in no way modify or affect the meaning or construction of any of the terms or provisions hereof. 

(h) Entire Agreement. This Agreement, together with the other agreements specifically referenced herein, embodies the entire agreement
and understanding between the parties hereto with respect to the subject matter hereof and supersedes all prior oral or written agreements and understandings relating to the subject matter hereof. No statement, representation, warranty, covenant or
agreement of any kind not expressly set forth in this Agreement shall affect, or be used to interpret, change or restrict, the express terms and provisions of this Agreement. 

(i) Counterparts. This Agreement may be executed in two or more counterparts, and by different parties hereto on separate counterparts,
each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. For all purposes a signature by fax shall be treated as an original. 

 

	 	10.	Reimbursement. 

 (a) Company agrees to reimburse Executive for reasonable legal fees and
expenses incurred in connection with the preparation of this Agreement up to $5,000. 
 [Signature Page to Follow] 

  
 13 

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

					
	CRISTINA LARKIN	  	 SPERO THERAPEUTICS, INC.
  

	 /s/ Cristina Larkin
	  	By:	  	 /s/ Patrick Vink

	 Signature
  
	  		  	 Name: Patrick Vink
 Title: Director, Chairman of
the Compensation Committee

	 Address:
  
	  		  	
	  
	  		  	

  
 14EX-10.14

 Exhibit 10.14 

CONFIDENTIAL TREATMENT REQUESTED 

ASSIGNMENT AND LICENSE AGREEMENT 

This ASSIGNMENT AND LICENSE AGREEMENT (this “Agreement”) is entered into as of May 9, 2016 (the “Effective
Date”), by and between Vertex Pharmaceuticals Incorporated, with an address at 50 Northern Avenue, Boston, Massachusetts 02210 (“Vertex”) and Spero Trinem, Inc., with an address at 675 Massachusetts Avenue, 14th Floor, Cambridge, Massachusetts 02139 (“Spero”) and solely for the purposes of Section 13.15, Spero Therapeutics, LLC, with an address at 675 Massachusetts Avenue, 14th Floor, Cambridge, Massachusetts 02139 (“Parent”). Vertex and Spero each may be referred to herein individually as a “Party” or collectively as the
“Parties.” 
 WHEREAS, Vertex owns rights to the proprietary compound identified as
VXc-100/VXc486; and 
 WHEREAS, Spero desires to obtain the rights to develop and
commercialize VXc-100/VXc486 and Vertex desires to grant such rights, all in accordance with the terms of this Agreement; 

NOW, THEREFORE, in consideration of the covenants and obligations set forth herein, and other good and valuable consideration, the
Parties agree as follows: 
 ARTICLE 1. 

DEFINITIONS 
 For purposes
of this Agreement, the following capitalized terms will have the meaning set forth below: 
 1.1. “Affiliate” means, as of
any point in time and for so long as such relationship continues to exist with respect to any Person, any other Person that controls, is controlled by or is under common control with such Person. A Person will be regarded as in control of another
Person if it (a) owns or controls more than 50% of the equity securities of the subject Person entitled to vote in the election of directors (or, in the case of a Person that is not a corporation, for the election of the corresponding managing
authority); provided, however, that the term “Affiliate” will not include subsidiaries or other entities in which a Person owns a majority of the ordinary voting power necessary to elect a majority of the board of directors
or other governing board, but is restricted from electing such majority by contract or otherwise, until such time as such restrictions are no longer in effect, or (b) possesses, directly or indirectly, the power to direct or cause the direction
of the management or policies of any such Person (whether through ownership of securities or other ownership interests, by contract or otherwise). 

1.2. “Agreement” has the meaning set forth in the preamble. 

1.3. “Anti-Corruption Laws” has the meaning set forth in Section 5.2. 

1.4. “Approval Application” means new drug application that is submitted to the FDA pursuant to 21 C.F.R. 314.3 or similar
application or submission for a Product filed with a Regulatory Authority in a country or group of countries to obtain Marketing Approval for a pharmaceutical product in that country or group of countries. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

 1.5. “Additional Compound” means any compound Covered by the claimed genus
in any issued Assigned Patent as the issued Assigned Patents exist as of the Effective Date, or a compound that would be Covered by a disclosed genus in any pending Assigned Patent as of the Effective Date should such disclosed genus issue to grant,
in each case including [***], other than the Assigned Compound. 
 1.6. “Assigned Compound” means each of (a) VXc-486 and (b) VXc-100 (the prodrug of VXc-486), including [***]. 

1.7. “Assigned Know-How” means the information identified in Exhibit B to the
extent Controlled by Vertex as of the Effective Date and to the extent solely and specifically related to the Assigned Compounds or Additional Compounds, but excluding all information related to Vertex’s general drug design, delivery,
formulation and manufacturing technologies and know-how applicable to or related to Vertex’s business in general and other programs. 

1.8. “Assigned Patents” means the Patents listed in Exhibit A, including any
re-examination, re-issue, continuation, or division thereof (to the extent that each claimed invention in such application is Covered by one or more claims in the
patents listed in Exhibit A) and any foreign counterparts filed or issued in the Territory. 
 1.9. “Associated
Persons” has the meaning set forth in Section 5.2. 
 1.10. “Business Day” means a Monday, Tuesday, Wednesday,
Thursday or Friday that is not a day on which banking institutions in Boston, Massachusetts are authorized or obligated to close. 
 1.11.
“Calendar Quarter” means the respective periods of three consecutive calendar months ending on March 31, June 30, September 30 or December 31, during the Term, or the applicable part thereof during the first or
last calendar quarter of the Term. 
 1.12. “Calendar Year” means any calendar year ending on December 31, or the
applicable part thereof during the first or last year of the Term. 
 1.13. “Change of Control” means, with respect to a
Party, (a) a merger or consolidation of such Party with a Third Party that results in the voting securities of such Party outstanding immediately prior thereto, or any securities into which such voting securities have been converted or
exchanged, ceasing to represent more than 50% of the combined voting power of the surviving entity or the parent of the surviving entity immediately after such merger or consolidation, or (b) a transaction or series of related transactions in
which a Third Party, together with its Affiliates, becomes the beneficial owner of more than 50% of the combined voting power of the outstanding securities of such Party, or (c) the sale or other transfer to a Third Party of all or
substantially all of such Party’s business to which the subject matter of this Agreement relates. For the avoidance of doubt, in no event shall a bona fide equity or debt financing of a Party, including a financing in which greater than 50% of
a Party’s outstanding equity securities are acquired by a Third Party, be deemed a “Change in Control.” 
 1.14.
“Claims” has the meaning set forth in Section 11.1. 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 2 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 1.15. “Combination Product” means any product, process or service which
incorporates one or more therapeutically active ingredients, other than an Assigned Compound or Additional Compound, in combination or co-formulation with an Assigned Compound or Additional Compound. 

1.16. “Commercialize” or “Commercialization” means (a) to market, promote, distribute, offer for sale,
sell, have sold, import, export or otherwise commercialize a Product and (b) to conduct activities other than Research, Development and Manufacturing, in preparation for the foregoing activities, including obtaining pricing approval, and to
conduct post-Marketing Approval studies (including clinical trials). 
 1.17. “Confidential Information” means all non-public, confidential or proprietary information, data or know-how, provided by one Party (the “Disclosing Party”) to the other Party (the
“Receiving Party”) in any form pursuant to this Agreement, including information relating to the Disclosing Party’s existing or proposed research, development, patent applications, business or products. Vertex’s
Confidential Information will include the Licensed Know-How. The Assigned Know-How will be deemed to be Spero’s Confidential information. The terms of this
Agreement will be deemed to be each Party’s Confidential Information. Confidential Information will not include any information or materials that the Receiving Party can document with competent written proof: 

(a) were already known to the Receiving Party (other than under an obligation of confidentiality) at the time of disclosure by
or on behalf of the Disclosing Party; 
 (b) were generally available to the public or otherwise part of the public domain at
the time of its disclosure to the Receiving Party; 
 (c) became generally available to the public or otherwise part of the
public domain after its disclosure to the Receiving Party, other than through any act or omission of the Receiving Party in breach of its obligations under this Agreement; 

(d) were disclosed to the Receiving Party, other than under an obligation of confidentiality, by a Third Party who had no
obligation to the Disclosing Party not to disclose such information to the Receiving Party or others; or 
 (e) were
independently discovered or developed by or on behalf of the Receiving Party without the use of the Confidential Information belonging to the Disclosing Party. 

Confidential Information disclosed to the Receiving Party hereunder will not be deemed to fall within the foregoing exceptions
merely because broader or related information falls within such exceptions, nor will combinations of elements or principles be considered to fall within the foregoing exceptions merely because individual elements of such combinations fall within
such exceptions. 
 1.18. “Controlled” means, with respect to any know-how, Patent
or other intellectual property right, possession of the right, whether directly or indirectly, and whether by ownership, license or otherwise, to assign, or grant a license, sublicense or other right to or under, such 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 3 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
know-how, Patent, or right as provided for herein without violating the terms of any agreement or other arrangements with any Third Party; provided
that if the assignment or license of such know-how, Patent or other intellectual property right would trigger a royalty or other payment to a Third Party or would require compliance with any provision
of any license between Vertex and a Third Party, Vertex will so notify Spero and such know-how, Patent or other intellectual property right will only be deemed Controlled if, following receipt of such notice,
Spero agrees in writing to reimburse Vertex for all such payments to such Third Party and comply with any such provision. 
 1.19.
“Cover,” “Covering,” “Covers” or “Covered” means, as to a compound or product and Patent, that, in the absence of a license granted under, or ownership of, such Patent, the making,
using, keeping, selling, offering for sale or importation of such compound or product would infringe such Patent or, as to a pending claim included in such Patent, the making, using, selling, offering for sale or importation of such compound or
product would infringe such Patent if such pending claim were to issue in an issued patent without modification. 
 1.20.
“Development” means, with respect to a Product, all clinical and non-clinical research and development activities conducted after filing of an IND for such Product, including toxicology,
pharmacology test method development and stability testing, process development, formulation development, delivery system development, quality assurance and quality control development, statistical analysis, clinical trials (other than
post-Marketing Approval clinical trials), regulatory affairs, pharmacovigilance, clinical trial regulatory activities and obtaining and maintaining regulatory approval. 

1.21. “Disclosing Party” has the meaning set forth in the definition of Confidential Information. 

1.22. “Effective Date” has the meaning set forth in the preamble. 

1.23. “EMA” means the European Medicines Agency and any successor entity thereto. 

1.24. “European Commission” means the European Commission or any successor entity that is responsible for granting marketing
approvals authorizing the sale of pharmaceuticals in the European Union. 
 1.25. “European Union” or “EU”
means all countries or territories that are officially part of the European Union. 
 1.26. “FDA” means the United States
Food and Drug Administration and any successor entity thereto. 
 1.27. “Field” means the diagnosis, treatment or prevention
of bacterial infections, excluding the [***]. 
 1.28. “First Commercial Sale” means, with respect to a particular Product
in a particular country in the Territory, the first commercial sale of such Product to a Third Party for end use or consumption in such country in an arm’s length transaction by Spero or any other Seller after the receipt of Marketing Approval
in such country. Sales for test marketing, sampling and promotional uses, clinical trial purposes or compassionate or similar use will not constitute a First Commercial Sale. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 4 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 1.29. “IND” means any Investigational New Drug application, filed with the
United States Food and Drug Administration pursuant to Part 312 of Title 21 of the U.S. Code of Federal Regulations, including any supplements or amendments thereto. References herein to IND will include, to the extent applicable, any comparable
filings outside the United States. 
 1.30. [***]. 

1.31. “Licensee” has the meaning set forth in Section 2.5(a). 

1.32. “Licensed Know-How” means all information other than Assigned Know-How that (a) was Controlled by Vertex as of the Effective Date and remains under the Control of Vertex during the Term, (b) was used by Vertex in its Research, Development or Manufacturing of the
Assigned Compounds or Additional Compounds and (c) is necessary for the Research, Development, use, Manufacturing or Commercialization of the Assigned Compound or Additional Compounds. Licensed Know-How
does not include Vertex’s general drug design or delivery technology, formulation and manufacturing technology, whether in hardware or software form, tangible or intangible, or information relating to any compounds or active ingredients other
than the Assigned Compound or Additional Compounds and formulation and manufacturing technology not applied to an Assigned Compound or Product containing an Assigned Compound by or on behalf of Vertex. 

1.33. “Manufacture” or “Manufactured” or “Manufacturing” means activities directed to
making, having made, producing, manufacturing, processing filling, finishing, packaging, labeling, quality control testing and quality assurance release, shipping or storage of a Product. 

1.34. “Marketing Approval” means, with respect to a Product in a particular jurisdiction, the receipt of all approvals,
licenses, registrations or authorizations necessary for the Commercialization of such Product in such jurisdiction, including, with respect to the United States, approval of an Approval Application for such Product by the FDA, with respect to the
European Union, approval of an Approval Application for such Product by the European Commission, and with respect to Japan, approval of an Approval Application for such Product by the Ministry of Health, Labor and Welfare or any successor government
agency responsible for approving the sale of pharmaceuticals in Japan. For clarity, Marketing Approval does not include reimbursement authorization or pricing approval determinations. 

1.35. “Materials” means raw materials, pharmaceutical ingredients, intermediates and drug products identified in Exhibit
C. 
 1.36. “Milestone Event” has the meaning set forth in Section 4.2. 

1.37. “Milestone Payment” has the meaning set forth in Section 4.2. 

1.38. “Monetization Transaction” has the meaning set forth in Section 4.6. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 5 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 1.39. “Net Sales” means the gross amount billed or invoiced by Spero, its
Related Parties and their Licensees, assignees, or any other Third Party to which Spero grants rights with respect to the Manufacturing and/or Commercialization of a Product (including by assignment of the Assigned Patents or Assigned Know-How) (collectively referred to as the “Seller”) on sales of a Product to a Third Party, less Permitted Deductions determined under United States generally accepted accounting principles.
“Permitted Deductions” means the following: 
 (a) customary transportation charges relating to such
Product, including handling charges, outbound freight, shipment and insurance premiums relating thereto; 
 (b) sales taxes,
excise taxes, use taxes, tariffs and duties paid by and not refunded to the seller and directly related to sale of such Product, and any other equivalent governmental charges imposed upon the importation, use or sale of such Product, but excluding
income and similar taxes; 
 (c) government-mandated deductions and other rebates (notably but not limited to those in
respect of any state or federal Medicare, Medicaid or similar programs), clawbacks or other forms of payment to any governmental authority or agency and payments or accruals made with respect to any national or local health insurance program,
including government fees levied as a result of health care reform policies such as the branded prescription drug fee of the Affordable Care Act; 

(d) customary trade, quantity and cash discounts, allowances and credits allowed or paid in the form of deductions actually
allowed or fees actually paid with respect to sales of such Product (to the extent not already reflected in the amount invoiced); 

(e) allowances or credits to customers on account of retrospective price reductions, rejections or returns of Product,
including billing errors; and 
 (f) customary rebates, charge backs and discounts (or equivalent thereof) actually granted
for such Product including those customarily granted to managed care entities or organizations, pharmacy benefit managers (or equivalent thereof), federal, state/provincial, local or other governments or their agencies or purchasers, reimbursers or
trade customers. 
 A Permitted Deduction set forth in Section 1.39(a)-1.39(f) above may be deducted only once,
regardless of the number of the preceding categories that describe such amount. A sale between or among Spero, or its Related Parties will be excluded from the computation of Net Sales if such sale is not intended for end use, but Net Sales will
include the subsequent final sales to Third Parties by Spero or any such Related Parties. A Product will not be deemed to be sold if the Product is provided free of charge to a Third Party in reasonable quantities as a sample consistent with
industry standard promotional and sample practices. For clarity, Net Sales includes [***]. 
 In the case of any sale that is not invoiced, Net Sales will
be calculated at the time of transfer of title of the Product based on the gross selling price. If a sale, transfer or other disposition with respect to a Product involves consideration other than cash or is not at arm’s length, then the Net
Sales from such sale, transfer or other disposition will be calculated based on the fair market value of the Product as reasonably determined by the Parties. 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 6 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 For all purposes of this Agreement, if a Product is a Combination Product, then for purposes of determining
Net Sales for such Combination Product, the actual Net Sales for such Combination Product (determined as provided above) will be [***]. 

1.40. “Party” or “Parties” has the meaning set forth in the preamble. 

1.41. “Patents” means patents existing upon the Effective Date and future patents and patent applications including without
limitation provisional applications, continuation applications, continuations-in-part, divisional applications, Patent Cooperation Treaty applications, invention
patents, utility model patents, industrial design patents, reexaminations, reissues, registrations, confirmations, revalidations, certificates of addition, utility models and petty patents, including extensions or restorations of terms thereof,
pediatric exclusivity extension of a patent, supplementary protection certificates or any other such right. 
 1.42. “Permitted
Deductions” has the meaning set forth in the definition of Net Sales. 
 1.43. “Person” means any natural person,
corporation, general partnership, limited partnership, limited liability company, joint venture, joint-stock company, proprietorship or other business organization or legal entity. 

1.44. “Phase 2 Clinical Trial” means any clinical trial described in 21 C.F.R. §312.21(b), or, with respect to a
jurisdiction other than the United States, a similar clinical trial. 
 1.45. “Phase 3 Clinical Trial” means any clinical
trial described in 21 C.F.R. §312.21(c), or, with respect to a jurisdiction other than the United States, a similar clinical trial. 

1.46. “Product” means any preparation, substance or formulation comprised, in whole or in part, of an Assigned Compound or an
Additional Compound. For the avoidance of doubt, Product includes any Combination Product or Single Agent Product. 
 1.47. “Progress
Report” has the meaning set forth in Section 7.1. 
 1.48. “Receiving Party” has the meaning set forth in the
definition of Confidential Information. 
 1.49. “Regulatory Authority” means, with respect to a country in the Territory,
any national (e.g., the FDA), supra-national (e.g., the European Commission, the Council of the European Union, or the EMA), regional, state or local regulatory agency, department, bureau, commission, council or other governmental authority involved
in the granting of Marketing Approvals or price approvals for pharmaceutical products in such country or countries. 
 1.50.
“Regulatory Exclusivity” means, upon Marketing Approval, the period during which a drug product is granted exclusive marketing rights by the FDA, European Commission, Ministry of Health, Labor and Welfare or the applicable
Regulatory Authority with respect to any country in the Territory or any successor Regulatory Authority. 
 1.51. “Related
Party” means each of Spero’s Affiliates and permitted Sublicensees. 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 7 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 1.52. “Research” means conducting research activities to advance the
Assigned Compounds, Additional Compounds and Products, including pre-clinical studies and optimization, but specifically excluding Development and Commercialization. 

1.53. “Revenue Buyer” has the meaning set forth in Section 4.6. 

1.54. “Royalty Term” means, with respect to a Product in a country, the period commencing on the first sale generating Net
Sales of such Product in such country and ending on the later of (a) ten years after the First Commercial Sale of such Product in such country or (b) the date of expiration of the last to expire Assigned Patent. 

1.55. “Seller” has the meaning set forth in the definition of Net Sales. 

1.56. “Single Agent Product” means any Product that is not a Combination Product. For clarity, a Product containing or
comprised of one or more Assigned Compounds and/or one or more Additional Compounds and no other therapeutically active ingredients will be deemed to be a Single Agent Product. 

1.57. “Storage Facility” has the meaning set forth in Section 2.6. 

1.58. “Sublicensee” means an Affiliate or Third Party, to whom Spero (or Spero’s Sublicensee or Affiliate) assigns,
licenses or sublicenses any of the rights granted to Spero hereunder during the Term. 
 1.59. “Term” has the meaning set
forth in Section 8.1. 
 1.60. “Territory” means worldwide. 

1.61. “Third Party” means any Person other than Vertex, Spero or their respective Affiliates. 

1.62. “Third Party Auditor” has the meaning set forth in Section 4.5. 

1.63. “United States” or “U.S.” means the United States of America and all of its districts, territories and
possessions. 
 1.64. “Spero” has the meaning set forth in the preamble. 

1.65. “Spero Indemnitees” has the meaning set forth in Section 11.2. 1.66. 

1.66. “Vertex” has the meaning set forth in the preamble. 

1.67. “Vertex Indemnitees” has the meaning set forth in Section 11.1. 

1.68. “Withheld Taxes” has the meaning set forth in Section 4.4(c)(ii). 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 8 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 ARTICLE 2. 

LICENSE; ASSIGNMENTS 
 2.1.
Assignment of Rights. Subject to the terms and conditions of this Agreement, Vertex hereby assigns to Spero, and Spero hereby accepts, all of Vertex’s right, title and interest in the Assigned Patents and Assigned Know-How, free and clear of all liens, claims, encumbrances, security interests, license, options, charges or restrictions of any kind or nature (collectively, “Liens”). If requested by Spero,
Vertex will reasonably cooperate with Spero to take all actions, including but not limited to the execution of patent assignments, customary and suitable written instruments or other documents reasonably requested by Spero to effect the assignment
of rights described in this Section 2.1. 
 2.2. License to Vertex. Notwithstanding the foregoing, effective upon the assignment
of Assigned Patents and Assigned Know-how pursuant to Section 2.1, Spero will, and hereby does, grant to Vertex a perpetual, irrevocable, exclusive, royalty-free, fully
paid-up, worldwide, sublicensable (through multiple tiers) license under any such Assigned Patents and Assigned Know-How to research, develop, manufacture, have
manufactured, use, keep, sell offer for sale, import, export and commercialize any Assigned Compound or Additional Compound for any use outside of the Field, including, without limitation, the use of the Assigned Compound and Additional Compounds in
any compound screening libraries and Vertex internal toxicity and DMPK databases that Vertex maintains. 
 2.3. Licensed Know-How. Subject to the terms and conditions of this Agreement, Vertex hereby grants to Spero a non-exclusive, royalty-bearing, revocable (as set forth in
Section 8.2), sublicenseable (solely as set forth in Section 2.5), nontransferable (except to the extent this Agreement is assigned by Spero in accordance with Section 13.2) license under the Licensed
Know-How to Research, Develop, Manufacture, have Manufactured, use, keep, sell, offer for sale, import, export and Commercialize the Assigned Compounds, Additional Compounds and Products containing the
Assigned Compounds and/or Additional Compounds, for use in the Field in the Territory during the Term. Notwithstanding the license granted to Spero under this Section 2.3, Vertex will not be obligated to provide Spero with access to, or copies
or physical embodiments of, any Licensed Know-How except as set forth herein. 
 2.4. Certain
Restriction. Spero (or its Affiliates or Licensees) will not use the Assigned Compounds, Additional Compounds, Licensed Know-How, Assigned Know-How, Assigned
Patents, or any other materials or information provided hereunder for purposes of researching, developing, commercializing or manufacturing products outside of the Field or relating to any other activities outside of the Field. 

2.5. Licensing; Sublicensing. 

(a) Spero will have the right to assign or grant licenses or sublicenses (through multiple tiers) under the rights assigned to
Spero pursuant to Section 2.1 to its Affiliates and any Third Party (each, a “Licensee” and collectively, the “Licensees”), without the prior written consent of Vertex; provided that (i) the
terms of any assignment, license or sublicense by Spero or a Licensee will be in a written agreement and consistent with the terms of this Agreement, (ii) Spero’s grant of any assignment, license or 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 9 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
sublicense will not relieve Spero from any of its obligations under this Agreement, (iii) Spero will remain responsible for its Licensees’ performance under this Agreement including
payment of royalties for Products by such Licensee and (iv) Spero will notify Vertex of the identity of any Licensee and the territory in which it has granted such assignment, license or sublicense, after entering into any such assignment,
license or sublicense. Notwithstanding the foregoing, before entering into any agreement with a Third Party in accordance with this Section 2.5(a) to Commercialize a Product, or any agreement to effectuate a Change of Control, Spero will notify
Vertex of its intent to license, sublicense or assign rights as provided in this Section 2.5(a) or undergo such Change of Control, which notice will specify the [***] or the [***] the Change of Control Spero intends to consummate, as
applicable, and Vertex may elect in writing within [***] after receipt of such notice to enter into good faith negotiations with Spero with respect to such transaction. If Vertex so elects, the Parties will in good faith negotiate the terms of such
transaction for a period of not less than [***]. During such [***] period, Spero will not offer any Third Party the opportunity to enter into the proposed transaction or enter into any such transaction. If Spero does undergo a Change of Control, the
obligation of Spero (or its successor) to notify Vertex of its intent to license, sublicense or assign rights as provided in this Section 2.5(a) or consummate an additional Change of Control, and Vertex’s right to elect to enter into good
faith negotiations with Spero (or such successor) with respect to a potential transaction, will terminate. 
 (b) Spero will
have the right to grant licenses or sublicenses (through multiple tiers) to a Licensee under the rights licensed to Spero under Section 2.3 (but may not assign such rights); provided that such license or sublicense is granted in
connection with an assignment or grant of rights under Section 2.5(a) and is granted for use solely in connection with the Research, Development, Manufacturing or Commercialization of the Assigned Compounds, Additional Compounds or Products and
subject to Spero’s compliance with Section 2.5(a). 
 2.6. Transfer of Materials. Vertex hereby transfers title and risk of
loss to the Materials to Spero in the quantities specified in Exhibit C. Within [***] after the Effective Date, Spero will either (a) make arrangements with the Third Party storing the Materials (the “Storage Facility”)
to ship the Materials to Spero or (b) enter into an agreement directly with the Storage Facility to continue storing the Materials at Spero’s expense. Vertex will notify the Storage Facility of the transfer of the Materials to Spero as
needed to facilitate the shipment of the Materials to Spero or the continued storage of the Materials by the Storage Facility at Spero’s expense and will execute all transfer letters or other documentation necessary in connection therewith.
Notwithstanding anything contained herein, if Spero does not notify Vertex of its election to either ship or continue storing such Materials with the Storage Facility within [***] after the Effective Date pursuant to this Section 2.6, such
Materials will be deemed to be rejected by Spero and Vertex may destroy the Materials. Except as expressly set forth herein, Spero will be solely responsible for all Manufacturing and supply of the Assigned Compound and Additional Compounds
(including without limitation for all costs and expenses associated therewith). With respect to any such Materials that are drug substances or drug products that were previously certified as to their suitability for clinical purposes, Spero will be
permitted, at its expense, to retest and have recertified, any such Materials, as suitable for human clinical 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 10 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
purposes. With respect to any Materials stored by a Storage Facility in any countries or jurisdictions outside of the United States, Spero will be responsible for obtaining, completing and
presenting to the applicable government authorities all export documentation, fees and license(s) required to ship such Materials. 

NOTWITHSTANDING ANYTHING CONTAINED HEREIN, THE MATERIALS ARE PROVIDED “AS-IS” AND VERTEX
MAKES NO REPRESENTATION OR WARRANTIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED, REGARDING THE MATERIALS, INCLUDING ANY WARRANTY OF MERCHANTABILITY, TITLE, INFRINGEMENT, OR FITNESS FOR A PARTICULAR PURPOSE. 

ARTICLE 3. 
 PERFORMANCE
OBLIGATIONS 
 3.1. Regulatory Approvals. As between the Parties, Spero will be responsible for obtaining all necessary
regulatory approvals, including Marketing Approval with respect to the Development, Manufacturing and Commercialization of the Assigned Compounds, Additional Compounds and Products. 

3.2. File/Knowledge Transfer. Within [***] after the Effective Date, Vertex will transfer copies of all Assigned Know-How in electronic format, if currently available, or such other form as mutually agreed by the Parties. Vertex will use commercially reasonable efforts to transfer such Assigned
Know-How and documents promptly. Notwithstanding the foregoing, Vertex will not be obligated to transfer any publically available information or documents pursuant to this Section 3.2. Vertex will provide
Spero with [***] of transition support at [***] for activities related to the knowledge transfer described in this Section 3.2. Notwithstanding anything contained herein, if any of the information or documents transferred pursuant to this
Section 3.2 inadvertently contains any information or documents relating to Vertex drug design, delivery, manufacturing or formulation technology or know-how, or any other technology or know-how that is related to or applicable to Vertex’s business in general or other programs, (a) Spero shall not use such information and, upon discovery, shall promptly send such information or documents
back to Vertex without retaining any copies thereof and (b) for the avoidance of doubt, such information and documents will be deemed Vertex Confidential Information. Spero will promptly reimburse Vertex for any reasonable out-of-pocket expenses incurred by Vertex in connection with the transfer of any Assigned Know-How under this Section 3.2. Vertex
may hold copies of all Assigned Know-How as required to comply with applicable law. 
 ARTICLE 4.

 FINANCIAL PROVISIONS 

4.1. Upfront Payment. In consideration of the rights granted by Vertex to Spero in the Assigned Patents set forth in Exhibit A,
on the Effective Date, Spero will pay to Vertex a one-time, non-refundable, non-creditable upfront fee of $500,000 USD. 

4.2. Milestone Payments. Spero will pay Vertex the milestone payments (each, a “Milestone Payment”) set forth in this
Section 4.2 within [***] after occurrence of the corresponding milestone event (each, a “Milestone Event”). Each Milestone Payment is payable only once, regardless of the number of Products that achieve the relevant Milestone
Event or the number of times Product(s) achieve such Milestone Event. 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 11 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 (a) Combination Product Development Milestones. Subject to
Section 4.2(e), Spero will pay Vertex the Milestone Payments set forth in this Section 4.2(a) upon the occurrence of the relevant Milestone Event, with respect to any Combination Product, regardless of whether the relevant Milestone Event
is achieved by Spero or its Related Parties. For clarity, the achievement of a Milestone Event with respect to a Combination Product will not constitute the achievement of the corresponding Milestone Event with respect to a Single Agent Product
under Section 4.2(b). 
  

							
	 Milestone Number
	  	 Milestone Event
	  	Milestone
Payment	 
	 1
	  	[***] a Combination Product [***]	  	$	[	***] 
	 2
	  	[***] a Combination Product	  	$	[	***] 
	 3
	  	[***] a Combination Product	  	$	[	***] 
	 4
	  	[***] a Combination Product	  	$	[	***] 
	 5
	  	[***] a Combination Product	  	$	[	***] 
	 6
	  	[***] a Combination Product	  	$	[	***] 

 (b) Single Agent Product Development Milestones. Subject to Section 4.2(e), Spero
will pay Vertex the Milestone Payments set forth in this Section 4.2(b) upon the occurrence of the relevant Milestone Event with respect to any Single Agent Product, regardless of whether the relevant Milestone Event is achieved by Spero or its
Related Parties. 
  
 Portions of this Exhibit, indicated by the
mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as
amended. 

  
 12 

 CONFIDENTIAL TREATMENT REQUESTED 

 

							
	 Milestone Number
	  	 Milestone Event
	  	Milestone
Payment	 
	 7
	  	[***] a Single Agent Product [***]	  	$	[	***] 
	 8
	  	[***] a Single Agent Product	  	$	[	***] 
	 9
	  	[***] a Single Agent Product	  	$	[	***] 
	 10
	  	[***] a Single Agent Product	  	$	[	***] 
	 11
	  	[***] a Single Agent Product	  	$	[	***] 
	 12
	  	[***] a Single Agent Product	  	$	[	***] 

 (c) Commercial Milestones. Subject to Section 1.39, Spero will pay Vertex the
Milestone Payments set forth in this Section 4.2(c), upon the occurrence of the relevant Milestone Event, regardless of whether the relevant Milestone Event is achieved by Spero or its Related Parties. 

 

							
	 Milestone Number
	  	 Milestone Event
	  	Milestone
Payment	 
	 13
	  	[***]	  	$	[	***] 
	 14
	  	[***]	  	$	[	***] 

 If the Milestone Events numbered 13 and 14 both above [***], both applicable Milestone Payments will be due to
Vertex. 
 (d) Notice; Payment; Skipped Milestones. The Milestones Events numbered
1-3 as set forth in Section 4.2(a) are intended to be successive with respect to Combination Products and the Milestone Events numbered 7-9 as set forth in
Section 4.2(b) are intended to be successive with respect to Single Agent Products; if a Combination Product or Single Agent Product, as applicable, is not required to undergo the event associated with any such Milestone Event, such skipped
Milestone Event will be deemed to have been achieved upon (and payment of such milestone shall be due therefor) the achievement by such Combination Product or Single Agent Product of the next successive Milestone Event. Payment for any such skipped
Milestone Event that is owed in accordance with the provisions of the foregoing sentence with respect to a given Product will be due concurrently with the payment for the next successive event by such Product, it being agreed that if a Product is
not required to undergo Milestone Event number 3 in Section 4.2(a) or Milestone Event number 9 in Section 4.2(b), the corresponding payment will be made upon the first to occur of the Milestone Events numbered 4-6 in Section 4.2(a) or the Milestone Events numbered 10-12 in Section 4.2(b). 

(e) Notwithstanding anything to the contrary contained herein, Spero will only be obligated to pay Vertex for [***] and will
make the corresponding Milestone Payment upon [***]. 
  
 Portions
of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of
the Securities Act of 1933, as amended. 

  
 13 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 4.3. Royalties. 

(a) Net Sales. On a Product-by-Product
and country-by-country basis, Spero will pay to Vertex royalties based on the aggregate Net Sales of all Products sold by Spero or its Related Parties in the Territory
during a Calendar Year at the rates set forth in the table below. The obligation to pay royalties will be imposed only once with respect to the same unit of a Product. 
  

					
	 Calendar Year Net Sales (in Dollars) for all Products
in the
Territory
	  	Royalty Rates as a Percentage
(%) of Net Sales	 
	 Portion of Calendar Year Net Sales up to and including $[***]
	  	 	[	***]% 
	 Portion of Calendar Year Net Sales that exceeds $[***], up to and including $[***]
	  	 	[	***]% 
	 Portion of Calendar Year Net Sales that exceeds $[***], up to and including $[***]
	  	 	[	***]% 
	 Portion of Calendar Year Net Sales that exceeds $[***]
	  	 	[	***]% 

 (b) Royalty Term. Spero will pay royalties to Vertex under this Section 4.3 on a Product-by-Product and country-by-country basis during the Royalty Term. Upon expiration of the
Royalty Term with respect to a given Product in a given country, the licenses granted to Spero under Section 2.3 will be fully paid perpetual and irrevocable with respect to such Product in such country. 

(c) Reduction for Lack of Patent Coverage and Regulatory Exclusivity. If during any period within the applicable Royalty
Term for a country, (a) no valid claim of an Assigned Patent exists that would, but for the licenses granted herein, be infringed by the Research, Development, Manufacture or Commercialization of the relevant Product in such country, and
(b) all applicable Regulatory Exclusivity periods, including data exclusivity periods, have expired in such country with respect to such Product, the royalty rate for such Product in such country will be reduced to [***] percent of the royalty
rate set forth in Section 4.3(a) for the remainder of the Royalty Term. If at any time, royalties are owed under this Section 4.3 with respect to more than one Product and the royalty rate applicable to one Product in one or more
countries, but not all Products in all countries, is reduced pursuant to this Section 4.3(c), then Net Sales of each Product will be allocated across the royalty tiers set forth in Section 4.3(a) pro rata based on the aggregate Net Sales
of each Product as compared to the aggregate Net Sales of all Products. 
 4.4. Payments. 

(a) Reports; Timing and Method. During the Term, following the first sale generating Net Sales of a Product giving rise
to Net Sales, Spero will deliver the following reports to Vertex: (i) within [***] after the end of each Calendar Quarter, a 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 14 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
flash report showing on a Product-by-Product and
country-by-country basis, estimated Net Sales in the Territory during the relevant Calendar Quarter and royalties payable under this Agreement on account of those Net
Sales; and (ii) within [***] after the end of each Calendar Quarter, a report specifying on a Product-by-Product and country-by-country basis: (A) gross sales in the relevant Calendar Quarter; (B) Net Sales in the relevant Calendar Quarter, including an accounting of Permitted Deductions applied to determine Net
Sales; (C) a summary of the exchange rate calculations used by Spero; (D) royalties payable on such Net Sales pursuant to this Agreement; and (E) additional information related to the Net Sales as reasonably requested by Vertex from
time to time. For the avoidance of doubt, the foregoing reports will clearly identify all Net Sales attributable to Spero as well as Spero’s Related Parties. Spero will pay all royalty payments due hereunder for each Calendar Quarter within
[***] after Spero’s delivery of the applicable reports under this Section 4.4(a). All payments due to Vertex under this Agreement will be made in U.S. dollars and be submitted via wire transfer of immediately available funds to an account
designated by Vertex. Conversion of any Net Sales made in foreign currency to U.S. dollars will be made at the average conversion rate for the applicable Calendar Quarter existing in the United States, as reported in the Wall Street Journal. Such
payments will be without deduction of exchange, collection, or other charges, and specifically, without deduction of withholding or similar taxes or other government-imposed fees or taxes, except as expressly permitted in the definition of Net
Sales. 
 (b) Late Payments. Without limiting any remedy available to Vertex hereunder, payments made by Spero after
the due date will bear interest at the rate of [***] percent per full month late (or, if lower, the highest rate allowed by applicable law). 

(c) Taxes; Withholding. 
  

	 	i.	Each Party will be solely responsible for the payment of all taxes imposed on its share of income arising directly or indirectly from this Agreement. 

 

	 	ii.	To the extent Spero or any Seller is required to deduct and withhold taxes on any payment to Vertex under this Agreement (“Withheld Taxes”), Spero will pay the amounts of Withheld Taxes to the proper
governmental authority in a timely manner and promptly transmit to Vertex an official tax certificate or other evidence of such withholding sufficient to enable Vertex to claim such payment of Withheld Taxes. Subject to the terms of this
Section 4.4(c)(ii), the sum payable by Spero (in respect of which such Withheld Taxes is required) will be made to Vertex after deduction of the Withheld Taxes. Vertex will provide Spero any tax forms that may be reasonably necessary in order
for Spero to not withhold tax or to withhold tax at a reduced rate under an applicable bilateral income tax treaty. Vertex will use reasonable efforts to provide any such tax forms to Spero at least [***] prior to the due date for any payment for
which Vertex desires that 

  
 Portions of this
Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the
Securities Act of 1933, as amended. 

  
 15 

 CONFIDENTIAL TREATMENT REQUESTED 

 

	 	
Spero apply a reduced withholding rate. Each Party will provide the other with reasonable assistance to enable the recovery, as permitted by applicable law, of withholding taxes, value added
taxes, or similar obligations resulting from payments made under this Agreement, such recovery to be for the benefit of the Party bearing such withholding tax or value added tax. 

4.5. Retention of Records; Audit. Spero agrees to make and keep, and will require its Related Parties to make and keep, full, accurate
and complete books and records (together with supporting documentation). Such records will contain sufficient detail to confirm the accuracy of any payments required hereunder. Such records will be retained for at least three years following the end
of the applicable Calendar Year. During normal business hours and no more than once per Calendar Year, Vertex, its duly authorized agent or independent certified public accounting representative acting on Vertex’s behalf (“Third Party
Auditor”) may conduct an audit in order to examine the foregoing books and records described in this Section 4.5 and any other supporting documentation reasonably necessary to verify the royalty reports submitted by Spero, at
Spero’s (or its Related Parties’ as applicable) business premises or at a place mutually agreed upon by the Parties for the purpose of verifying reports and payments hereunder. If a payment deficiency is determined by Vertex or its Third
Party Auditor, Spero will pay the deficiency outstanding within [***] after receiving written notice of the deficiency. Such examination by Vertex or its Third Party Auditor will be at Vertex’s expense, except that, if such examination shows an
underreporting or underpayment in excess of [***] percent of the sums due to Vertex as determined by such audit, then Spero will pay the reasonable out of pocket cost of such audit or reimburse Vertex for the reasonable expenses incurred by Vertex
in connection with such audit. Vertex will treat all information subject to review under this Section 4.5 in accordance with the confidentiality obligations set forth in Article 9 of this Agreement, and any Third Party Auditor to whom Vertex
discloses financial information will be subject to confidentiality obligations with respect to such financial information that are no less restrictive than those contained in this Agreement. 

4.6. Monetization Transaction. Vertex may, at any time, monetize all or a portion of the value of the payments to which it may be
entitled to receive under this Article 4 by assigning to a Third Party (a “Revenue Buyer”) the right to receive such payments (a “Monetization Transaction”); provided that Vertex has put in place
adequate and customary confidentiality provisions at least as stringent as those applicable to Vertex hereunder with the Revenue Buyer. In the event of a Monetization Transaction, Spero will make such payments to the Revenue Buyer as directed by
Vertex and shall deliver notices and provide reports directly to the Revenue Buyer as directed by Vertex. 
 ARTICLE 5. 

REPRESENTATIONS AND WARRANTIES 
  

5.1. Mutual Representations and Warranties. Vertex and Spero each represents and warrants to the other as of the Effective Date that:
(a) such Party (i) is a company duly organized, validly existing, and in good standing under the laws of its jurisdiction of incorporation, (ii) is duly qualified as a corporation and in good standing under the laws of each
jurisdiction where its ownership or lease of property or the conduct of its business requires such 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 16 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
qualification, where the failure to be so qualified would have a material adverse effect on its financial condition or its ability to perform its obligations hereunder, (iii) has the
requisite corporate power and authority and the legal right to conduct its business as now conducted and (iv) is in compliance with its charter documents; (b) the execution, delivery and performance of this Agreement by such Party and all
instruments and documents to be delivered by such Party hereunder (i) are within the corporate power of such Party, (ii) have been duly authorized by all necessary or proper corporate action, (iii) do not conflict with any provision
of the charter documents of such Party and (iv) will not, to such Party’s knowledge, violate any laws or regulation or any order or decree of any court of governmental instrumentality, (v) will not violate or conflict with any terms
of any indenture, mortgage, deed of trust, lease, agreement, or other instrument to which such Party is a party, or by which such Party or any of its property is bound, which violation would have a material adverse effect on its financial condition
or on its ability to perform its obligations hereunder; and (c) this Agreement has been duly executed and delivered by such Party and constitutes a legal, valid and binding obligation of such Party, enforceable against such Party in accordance
with its terms, except as such enforceability may be limited by applicable insolvency and other laws affecting creditors’ rights generally, or by the availability of equitable remedies. 

5.2. Spero Representations; Legal Compliance; Anti-Corruption Laws. Spero represents and warrants that Spero, as well as all Persons
performing services for or on behalf of Spero or otherwise acting on its behalf (including any agent, subcontractor, subsidiary, representative, employee, shareholder, director or officer) (“Associated Persons”) will comply with all
applicable laws and regulations in connection with all work conducted hereunder, including (a) the United States Foreign Corrupt Practices Act and other applicable anti-corruption and anti-bribery laws (collectively, the
“Anti-Corruption Laws”), (b) all laws and regulations relating to import and export and (c) all laws and regulations relating to the development, testing, marketing, sale, commercialization, and other exploitation of
pharmaceuticals. Without limiting the foregoing, (i) Spero will not (and will procure that each Associated Person will not) perform, or fail to perform, any act that will cause or lead Vertex to be in breach of Anti-Corruption Laws and
(ii) Spero represents and warrants neither it, nor any Associated Person, offers, agrees or promises to give, or authorizes the giving directly or indirectly, of any money or other thing of value to anyone as an inducement or reward for
favorable action or forbearance from action or the exercise of influence (A) to any governmental official or employee (including employees of government-owned and government-controlled corporations or agencies), (B) to any political party,
official of a political party, or candidate, (C) to an intermediary for payment to any of the foregoing or (D) to any other Person or entity in a corrupt or improper effort to obtain or retain business or any commercial advantage, such as
receiving a permit or license. Spero further warrants and represents that should it learn or have reason to suspect any breach of its covenants in this Section 5.2, it will immediately notify Vertex. 

5.3. Vertex Representations and Warranties. Subject to Section 2.1, Vertex hereby represents and warrants that prior to the
Effective Date, Vertex, to its knowledge, has not previously assigned, transferred, conveyed or otherwise encumbered its right, title and interest in and to the Assigned Patents in any way that would prevent Spero or its Affiliates and
subcontractors from Researching, Developing or Commercializing the Assigned Compounds or Products containing the Assigned Compounds as set forth herein, or from exploiting its rights and licenses granted under Article 2 above. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 17 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 5.4. Disclaimer. EXCEPT FOR THE EXPRESS WARRANTIES SET FORTH IN THIS Article 5,
NEITHER VERTEX NOR SPERO MAKES ANY REPRESENTATIONS OR WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, WITH RESPECT TO THE SUBJECT MATTER OF THIS AGREEMENT, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR
PURPOSE, OR NONINFRINGEMENT, EACH OF WHICH ARE HEREBY EXPRESSLY DISCLAIMED. WITHOUT LIMITING THE FOREGOING, EXCEPT FOR THE EXPRESS WARRANTY IN SECTION 5.3, VERTEX MAKES NO WARRANTIES OR REPRESENTATIONS OF ANY KIND OR NATURE WITH RESPECT TO THE
PATENTABILITY OF THE ASSIGNED COMPOUNDS, ADDITIONAL COMPOUNDS, OR PRODUCTS OR VALIDITY, SCOPE, OR ENFORCEABILITY OF THE ASSIGNED PATENTS OR ANY CLAIMS THEREIN, OR THE PRACTICE, INCLUDING BUT NOT LIMITED TO FREEDOM TO OPERATE, REGARDING ANY ASSIGNED
COMPOUND, ADDITIONAL COMPOUND, OR PRODUCT. EXCEPT AS EXPRESSLY SET FORTH IN SECTION 5.3, ALL RIGHTS GRANTED TO SPERO HEREUNDER ARE PROVIDED ON AN AS-IS BASIS. 

ARTICLE 6. 
 COVENANTS

 6.1. At Vertex’s request, Spero will discuss in good faith with a non-profit organization
designated by Vertex the possibility of establishing a relationship with such non-profit organization with respect to discovery, research, development, manufacture and/or commercialization of Products for use
in the treatment of [***]. 
 ARTICLE 7. 

PROGRESS REPORTS 
 7.1.
Progress Reports. Spero will submit [***] progress reports on its efforts to Develop and Commercialize the Assigned Compound and Additional Compounds (“Progress Reports”). Spero will submit the first Progress Report [***] and
subsequent reports every [***] thereafter. 
 Within [***] after the Effective Date, Spero will provide to Vertex a report with respect to
the [***] for the [***] period after the Effective Date and subsequently update such report for the [***] period commencing on January 1st within the first [***] after the end of each Calendar
Year. 
 7.2. Confidential Treatment. Vertex acknowledges and agrees that any reports provided pursuant to Sections 4.4(a) or 7.1 will
constitute the Confidential Information of Spero, except to the extent that they contain information relating to the Licensed Know-How or other Vertex Confidential Information. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 18 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 ARTICLE 8. 

TERM 
 8.1. Term.
This Agreement will commence on the Effective Date and will continue in effect until expiration of all payment obligations under Article 4 (the “Term”). 

8.2. License Termination for Cease in Development. If Spero provides Vertex with notification of its intent to cease all Development
hereunder or if no material Development or Commercialization occurs for a period of 12 consecutive calendar months, Vertex may terminate the license granted pursuant to Section 2.3 upon written notice to Spero, and Spero will immediately cease
all use of the Licensed-Know How following its receipt of such notice. 
 8.3. Surviving Provisions. The following Articles and
Sections will survive expiration of this Agreement: Article 1, Article 4 (to the extent any amounts are due and payable at the time of expiration), Article 6, this Article 8, Article 9, Article 10, Article 11, Article 12, Article 13, Sections 2.1,
2.5, 5.2, 5.4 and 7.2. 
 ARTICLE 9. 

CONFIDENTIALITY 
 9.1.
Confidential Information. Each of Spero and Vertex will (and will cause their respective Affiliates and Licensees to): (a) keep all Confidential Information received from the Disclosing Party confidential with the same degree of care it
maintains the confidentiality of its own Confidential Information; (b) not publish, or allow to be published, and will not otherwise disclose, or permit the disclosure of the Disclosing Party’s Confidential Information in any manner not
expressly authorized pursuant to the terms of this Agreement; and (c) not use, or permit to be used, the Disclosing Party’s Confidential Information for any purpose other than as expressly authorized pursuant to the terms of this
Agreement. No disclosure of the Disclosing Party’s Confidential Information will be made by the Receiving Party to its employees, directors, officers, agents and other Persons unless and until such employees, directors, officers, agents,
contractors and other Persons have agreed in writing to comply with confidentiality and non-use obligations substantially similar to those described herein. Upon termination of this Agreement, the Receiving
Party will return or destroy, at the Disclosing Party’s request, all documents, tapes or other media containing Confidential Information of the Disclosing Party that remain in the Receiving Party’s, its agents’ or contractors’
possession, except that the Receiving Party may keep one copy of the Confidential Information in the legal department files of the Receiving Party, solely for archival purposes and neither the Receiving Party, nor any of its agents, contractors or
other representatives will be required to delete or destroy any electronic back-up tapes or other electronic back-up files that have been created solely by the automatic
or routine archiving and back-up procedures of the Receiving Party or its representatives, to the extent created and retained in a manner consistent with its or their standard archiving and back-up procedures. Such archival copies will be deemed to be the property of the Disclosing Party, and will continue to be subject to the provisions of this Article 9 notwithstanding any expiration of this
Agreement or otherwise. Each Party will be liable for breach of this Article 9 by any of its agents, Related Parties, subcontractors, or its Affiliates’ sublicensees and subcontractors. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 19 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 9.2. Permitted Disclosure and Use. Notwithstanding Section 9.1, a Party may
disclose Confidential Information belonging to the other Party only to the extent such disclosure is reasonably necessary: (a) to obtain Marketing Approval of the Product or any other necessary permissions, approvals and other documents issued
by governmental authorities; provided that all such disclosures pursuant to this subsection 9.2(a) are covered by terms of confidentiality and non-use substantially similar to those set forth
herein; (b) to perform or exercise such Party’s rights under this Agreement; provided that (i) Confidential Information disclosed to such Party’s Affiliates, licensors, licensees or sublicensees, directors,
officers, employees, consultants, representatives or agents, or other Third Parties (including existing or potential acquirers, acquisition targets, collaborators, investment bankers, accountants, attorneys, investors, merger candidates, partners,
venture capital firms or other financial institutions or investors) is, in each case, on a need-to-know basis and solely for business purposes relevant to and permitted
by this Agreement, (ii) each individual and entity to whom such Confidential Information is disclosed is bound in writing to non-use and non-disclosure obligations
no less than substantially as restrictive as those set forth in this Agreement and (iii) the Party making such disclosure shall be liable for such Third Parties’ compliance with such obligations; or (c) to comply with any applicable
law or regulation (including the rules and regulations promulgated by the United States Securities and Exchange Commission or any equivalent governmental agency in any country in the Territory); provided that the Party making such disclosure
will reasonably consider the comments of the other Party regarding confidential treatment sought for any disclosure. If a Party deems it necessary to disclose Confidential Information of the other Party pursuant to this Section 9.2, such Party
will give reasonable advance notice of such intended disclosure to the other Party to permit such other Party sufficient opportunity to object to such disclosure or to take measures to ensure confidential treatment of such information. The Receiving
Party will cooperate reasonably with the Disclosing Party’s efforts to protect the confidentiality of the information. Notwithstanding Section 9.1, Vertex may disclose Spero’s Confidential Information to a Revenue Buyer or a bona fide
potential Revenue Buyer as reasonably necessary in connection with a Monetization Transaction or proposed Monetization Transaction, including a copy of this Agreement and information related to the royalties payable by Spero to Vertex such as
financial reports indicating the amounts that are the subject of the Monetization Transaction, audit reports related to such amounts, if any, and notices and other correspondence; provided that such Confidential Information under or
relating to the subject matter of this Agreement is relevant to the Monetization Transaction; provided further that each recipient of such Confidential Information shall be under an obligation of confidentiality no less protective than the terms of
this Agreement. 
 9.3. Public Announcements. Except as set forth in this Section 9.3 and as required by applicable laws, neither
Party will make any public announcement of any information regarding this Agreement, the Assigned Compounds, Additional Compounds, or any activities under this Agreement without the prior written approval of the other Party (the “Approving
Party”). Notwithstanding the foregoing, within 20 days after the Effective Date, Spero will issue a press release announcing the execution of this Agreement in a form mutually agreed upon by the Parties. Once any statement is approved for
disclosure by the Approving Party or information is otherwise made public in accordance with the preceding sentence, the disclosing Party may make a subsequent public disclosure of the contents of such statement without further approval by the
Approving Party. Notwithstanding the foregoing, Spero will give Vertex the opportunity to review and comment on any proposed public announcement five days prior to 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 20 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 
such public announcement (unless otherwise required by applicable law) and Spero will use good faith efforts to incorporate any suggested changes to any public announcement requested by Vertex
that are for the purpose of protecting the Vertex Confidential Information. 
 9.4. Survival. The obligations and prohibitions
contained in this Article 9 will survive the expiration of this Agreement for a period of [***] years, except with respect to Confidential Information which constitutes a trade secret under applicable law, which will survive for such additional
period of time during which such Confidential Information constitutes the Disclosing Party’s trade secret under applicable law. 

ARTICLE 10. 
 ADDITIONAL
INTELLECTUAL PROPERTY MATTERS 
 10.1. Spero will be solely responsible for filing, prosecution, and maintenance of all of the Assigned
Patents, as well as all internal and external costs and expenses associated therewith. Vertex will have no responsibility or liability for, or relating to, the Assigned Patents. For the avoidance of doubt, Vertex will retain sole ownership of and
all intellectual property rights in and to the Licensed Know-How and does not grant Spero any interest in such Licensed Know-How except as expressly set forth in
Section 2.3 of this Agreement. 
 ARTICLE 11. 

INDEMNIFICATION 
 11.1.
Indemnification by Spero. Spero will defend, indemnify and hold harmless Vertex and its Affiliates and each of their respective officers, directors, shareholders, employees, agents, successors and assigns (“Vertex
Indemnitees”) from and against all charges, complaints, actions, suits, proceedings, hearings, investigations, claims and demands (“Claims”) of Third Parties, and all associated damages and losses resulting therefrom
(including attorneys’ fees), to the extent arising out of (a) any material breach by Spero of its representations, warranties or obligations under this Agreement, or (b) the Research, Development, Manufacturing, Commercialization,
use, licensing, handling, storage, marketing, sale, offer for sale, importation, exportation, distribution or other disposition of, any Assigned Compound, Additional Compound, or Product, including any product Covered by the Assigned Patents or
incorporating the Assigned Know-How, by Spero, its Affiliates, agents, or Licensees. Notwithstanding the foregoing, Spero will have no obligation under this Agreement to indemnify, defend or hold harmless any
Vertex Indemnitees with respect to any such Claims to the extent that they result from the negligence or willful misconduct of Vertex or a Vertex Indemnitee or Vertex’s breach of its obligations under this Agreement. 

11.2. Indemnification by Vertex. Vertex will defend, indemnify and hold harmless Spero and its Affiliates and each of their officers,
directors, shareholders, employees, agents, successors and assigns (“Spero Indemnitees”) from and against all Claims of Third Parties, and all associated damages and losses resulting therefrom, to the extent arising out of any
material breach by Vertex of its obligations under this Agreement. Notwithstanding the foregoing, Vertex will have no obligation under this Agreement to indemnify, defend or hold harmless any Spero Indemnitees with respect to any such Claims and
Losses to the extent that Spero is obligated to indemnify Vertex for such Claim pursuant to Section 11.1. Notwithstanding anything to the contrary in this Agreement, the indemnification provided in this Section 11.2 will be Spero’s
sole and exclusive remedy, and Vertex’s entire liability for, any and all claims, Third Party or otherwise, arising out of or relating to this Agreement or any of the rights granted herein. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 21 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 11.3. Conditions to Indemnification. The obligations of the indemnifying Party under
this Article 11 are conditioned upon the delivery of written notice to the indemnifying Party of any Claim promptly after the indemnified Party becomes aware of such Claim; provided that failure of the indemnified Party to promptly notify the
indemnifying Party of a Claim will not constitute a waiver of, or result in the loss of, the indemnified Party’s right to indemnification under Sections 11.1 or 11.2, as applicable, except to the extent that the indemnifying Party’s
ability to defend against such Claim is materially prejudiced by such failure to notify. The indemnifying Party will have the right to assume control of the defense and/or settlement of any such Claim; provided that the indemnifying Party
will keep the indemnified Party reasonably informed of all material developments in such defense. Notwithstanding the foregoing, the indemnified Party may participate in the defense of any Claim at its sole cost and expense. 

11.4. Settlements. Except for settlements that would solely impose a monetary obligation on the indemnifying Party and for which the
indemnifying Party will by fully responsible, the indemnifying Party will not settle or resolve a Claim or action with respect to such a Claim without the prior written consent of the indemnified Party, such consent not be unreasonably withheld. Any
payment made by a Party to settle any such Claim or action will be at its own cost and expense. 
 ARTICLE 12. 

LIMITATION OF LIABILITY 

12.1. EXCEPT FOR (A) A BREACH BY EITHER PARTY OF Article 9 (CONFIDENTIALITY), (B) SPERO’S INDEMNIFICATION OBLIGATIONS HEREUNDER OR
(C) EITHER PARTY’S FRAUD OR WILFUL MISCONDUCT, NEITHER PARTY WILL BE LIABLE TO THE OTHER WITH RESPECT TO ANY SUBJECT MATTER OF THIS AGREEMENT FOR ANY INDIRECT OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, LOSS OF GOODWILL, PUNITIVE OR
INCIDENTAL DAMAGES. VERTEX’S ENTIRE LIABILITY ARISING OUT OF OR RELATING TO THIS AGREEMENT AND ANY SUBJECT MATTER REFERENCED HEREIN UNDER ANY LEGAL OR EQUITABLE THEORY, INCLUDING CONTRACT, NEGLIGENCE, STRICT LIABILITY, OR OTHERWISE WILL NOT
EXCEED $[***] USD. 
 ARTICLE 13. 

MISCELLANEOUS 
 13.1.
Insurance. During the Term of this Agreement and for a period of [***] after the expiration of this Agreement, Spero will obtain and maintain at its sole cost and expense, liability insurance (including without limitation product liability
insurance) in amounts which are reasonable and customary in the Territory for companies who are Developing, Marketing and Commercializing products and services similar to Products. Such liability insurance will insure against all liability,
including without limitation personal injury, physical injury, or property damage arising out of the Manufacture, sale, distribution, or marketing of the Product. Spero will provide written proof of the existence of such insurance to Vertex upon
reasonable request. 
  
 Portions of this Exhibit, indicated by the
mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as
amended. 

  
 22 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 13.2. Assignment. This Agreement may not be assigned by either Party without the prior
written consent of the other Party; provided, however, that either Party may assign this Agreement, in whole or in part, to any of its Affiliates if such Party guarantees the performance of this Agreement by such Affiliate; and
provided further that either Party may assign this Agreement to a successor to all or substantially all of the assets of such Party pertaining to this Agreement pursuant to a Change of Control. This Agreement will be binding
upon, and subject to the terms of the foregoing sentence, inure to the benefit of the Parties hereto, and their permitted successors, legal representatives and assigns. 

13.3. Notices. All demands, notices, consents, approvals, reports, requests and other communications hereunder must be in writing and will be
deemed to have been duly given only if delivered personally, by mail (first class, postage prepaid, certified), or by overnight delivery using a globally recognized carrier, to the Parties at the addresses set forth below or to such other address as
the addressee will have last furnished in writing in accord with this provision to the addressor. All notices will be deemed effective: (a) when delivered if personally delivered on a Business Day (or if delivered or sent on a non-business day, then on the next Business Day); or (b) on receipt if sent by mail or overnight courier. 

If to Vertex: 
 Vertex
Pharmaceuticals Incorporated 
 Attn: Business Development 

50 Northern Avenue 
 Boston,
Massachusetts 02210 
 With a copy to: 

Vertex Pharmaceuticals Incorporated 

Attn: Corporate Legal 
 50
Northern Avenue 
 Boston, Massachusetts 02210 

If to Spero: 
 Spero Therapeutics,
Inc. 
 675 Massachusetts Avenue, 14th Floor 

Cambridge, Massachusetts 02139 

13.4. Severability. In the event of the invalidity of any provisions of this Agreement, the Parties agree that such invalidity will not
affect the validity of the remaining provisions of this Agreement. The Parties will replace an invalid provision with valid provisions which most closely approximate the purpose and economic effect of the invalid provision. Nothing in this Agreement
will be interpreted so as to require either Party to violate any applicable laws, rules or regulations. 
  

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and
Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 23 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 13.5. Headings. The headings used in this Agreement have been inserted for convenience
of reference only and do not define or limit the provisions hereof. 
 13.6. Waiver. Any term or condition of this Agreement may be
waived at any time by the Party that is entitled to the benefit thereof, but no such waiver will be effective unless expressly set forth in a written instrument duly executed by or on behalf of the Party waiving such term or condition. No provision
of this Agreement will be waived by any act, omission or knowledge of a Party or its agents or employees except as expressly set forth in this preceding sentence. No waiver by any Party of any term or condition of this Agreement, in any one or more
instances, will be deemed to be or construed as a waiver of the same or any other term or condition of this Agreement on any future occasion. Except as expressly set forth in this Agreement, all rights and remedies available to a Party, whether
under this Agreement or afforded by law or otherwise, will be cumulative and not in the alternative to any other rights or remedies that may be available to such Party. 

13.7. Entire Agreement. This Agreement (including the exhibits and schedules hereto) constitutes the entire agreement between the
Parties hereto with respect to the subject matter described herein and supersedes all previous agreements and understandings between the Parties, whether written or oral, including the Mutual Confidentiality Agreement between the Parties dated
January 5, 2015. This Agreement may be altered, amended or changed only by a writing making specific reference to this Agreement and signed by duly authorized representatives of Vertex and Spero. 

13.8. No License. Nothing in this Agreement will be deemed to constitute the grant of any license or other right in either Party, to or
in respect of the Product, Assigned Compound, Additional Compounds, Patent, trademark, Confidential Information, trade secret or other data or any other intellectual property of the other Party, except as expressly set forth herein. 

13.9. Third Party Beneficiaries. None of the provisions of this Agreement will be for the benefit of or enforceable by any Third Party,
including without limitation any creditor of either Party hereto. No such Third Party will obtain any right under any provision of this Agreement or will by reasons of any such provision make any Claim in respect of any debt, liability or obligation
(or otherwise) against either Party hereto. 
 13.10. Counterparts. This Agreement may be executed in any two counterparts, each of
which, when executed, will be deemed to be an original and both of which together will constitute one and the same document. 
 13.11.
Language. This Agreement is written and executed in the English language. Any translation into any other language will not be an official version of this Agreement. In the event of any conflict in interpretation between the English language
version of this Agreement and any other instrument or document related to this Agreement or the business relationship between the Parties contemplated hereby, the English language version of this Agreement will prevail. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 24 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 13.12. Section 365(n) of the Bankruptcy Code. All rights and licenses granted under or
pursuant to any section of this Agreement are, and will otherwise be deemed to be, for purposes of Section 365(n) of the U.S. Bankruptcy Code, licenses of rights to “intellectual property” as defined under Section 101(35A) of the
Bankruptcy Code. Each Party will retain and may fully exercise all of its rights and elections under the Bankruptcy Code or equivalent legislation in any other jurisdiction. Upon the bankruptcy of either Party, the other Party will further be
entitled to a complete duplicate of (or complete access to, as appropriate) any such intellectual property for which a license has been granted to such Party hereunder, and such intellectual property, if not already in its possession, will be
promptly delivered to such other Party, unless the Party in bankruptcy elects to continue, and continues, to perform all of its obligations under this Agreement. 

13.13. Governing Law. This Agreement will be governed by and construed in accordance with the laws of The Commonwealth of Massachusetts,
excluding any conflicts or choice of law rule or principle that might otherwise refer construction or interpretation of this Agreement to the substantive law of another jurisdiction. 

13.14. Independent Parties/Entities. The relationship of Vertex and Spero is that of independent parties and not as agents of each
other, partners, or participants in a joint venture. Vertex and Spero will each maintain sole and exclusive control over their respective personnel and operations. 

13.15. Parent. Parent will cause Spero to perform its obligations under, and to comply with the terms and conditions of, this Agreement.
If Spero fails to perform any of its obligations under this Agreement, Parent shall indemnify Vertex from and against any and all losses, damages, expenses, liabilities, claims, costs or proceedings which Vertex may suffer of incur by reason of such
failure. If Parent undergoes any reorganization, as part of such reorganization, it will provide Vertex with the guarantee set forth in this Section 13.15 from its successor. 

 
 Portions of this Exhibit, indicated by the mark “[***],”
were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of 1933, as amended. 

  
 25 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be executed by their
authorized representatives as of the Effective Date. 
  

			
	 SPERO TRINEM, INC.
	  	 VERTEX PHARMACEUTICALS INCORPORATED

		
	 By: /s/ Ankit
Mahadevia                                    

Name: Ankit Mahadevia

Title:   Director
	  	 By: /s/ David
Altshuler                                        
    
 Name: David Altshuler

Title:   Executive Vice President and Chief

    Scientific Officer

		
	 SPERO THERAPEUTICS, INC.
	  	
		
	 By: /s/ Ankit
Mahadevia                                    

Name: Ankit Mahadevia

Title:   CEO and Director
	  	

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  
 26 

 CONFIDENTIAL TREATMENT REQUESTED 

 

 EXHIBIT A 

Assigned Patents 
 [***]: covers
[***] 
 [***]: covers [***] 
 [***]: [***] 

[***]: covers [***] 
 [***]: covers [***] 

[***]: covers [***] 
 [***]: [***]. 

 

																													
	 Docket

Number
	  	Country	 	 	Status	 	 	Application
Serial No	 	 	Filing
Date	 	 	Patent
Number	 	 	Patent
Issue
Date	 	 	Case
Title	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

																													
	 Docket

Number
	  	Country	 	 	Status	 	 	Application
Serial No	 	 	Filing
Date	 	 	Patent
Number	 	 	Patent
Issue
Date	 	 	Case
Title	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

																													
	 Docket

Number
	  	Country	 	 	Status	 	 	Application
Serial No	 	 	Filing
Date	 	 	Patent
Number	 	 	Patent
Issue
Date	 	 	Case
Title	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

																													
	 Docket

Number
	  	Country	 	 	Status	 	 	Application
Serial No	 	 	Filing
Date	 	 	Patent
Number	 	 	Patent
Issue
Date	 	 	Case
Title	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

																													
	 Docket

Number
	  	Country	 	 	Status	 	 	Application
Serial No	 	 	Filing
Date	 	 	Patent
Number	 	 	Patent
Issue
Date	 	 	Case
Title	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  				 				 				 				 				 				 			
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 
	 [***]
	  	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 	 	[***]	 	 				 				 	 	[***]	 

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

															
	 Docket

Number
	  	Country	 	Status	 	Application
Serial No	 	Filing
Date	 	Patent
Number	  	Patent
Issue
Date	  	Case
Title
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 		  		  	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 		  		  	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 		  		  	[***]

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

 EXHIBIT B 

Assigned Know-How 

The following Assigned Know-How is located [***]: 

 

											
	 	  	Total
Files	 	Files
in
Folder	 	Size	 	Last
Modified
Date	 	Added
on
Date
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

											
	 	  	Total
Files	 	Files
in
Folder	 	Size	 	Last
Modified
Date	 	Added
on
Date
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  		 		 	[***]	 	[***]	 	[***]
	 [***]
	  		 		 	[***]	 	[***]	 	[***]
	 [***]
	  		 		 	[***]	 	[***]	 	[***]
	 [***]
	  		 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

											
	 	  	Total
Files	 	Files
in
Folder	 	Size	 	Last
Modified
Date	 	Added
on
Date
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 	[***]	 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]
	 [***]
	  	[***]	 		 	[***]	 	[***]	 	[***]

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended. 

  

 CONFIDENTIAL TREATMENT REQUESTED 

 

 EXHIBIT C 

Materials 
  

			
	 Third Party Storage Facility
	  	Materials
	 [***]
	  	[***]
	 [***]
	  	[***]

  
 Portions of this Exhibit, indicated
by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 406 of the Securities Act of
1933, as amended.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00275-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00275-of-00352.parquet"}]]