Document:

EX-10.16

 Exhibit 10.16 

CONFIDENTIAL TREATMENT REQUESTED 

Execution Version 
 AMENDED AND RESTATED
LICENSE AGREEMENT 
 This Amended and Restated License Agreement (this “Agreement”), dated as of June 28, 2017 (the
“Effective Date”), is made by and between Northern Antibiotics Oy (Ltd.), a corporation organized under the laws of Finland (“Northern”), and Spero Potentiator, Inc., a Delaware corporation (“Spero”). Northern and Spero
are sometimes hereinafter referred to each as a “Party” and collectively as the “Parties.” 
 WHEREAS, the parties
previously entered into that certain License Agreement (the “Prior Agreement”), dated as of February 16, 2015 (the “Initial Effective Date”), pursuant to which Spero acquired exclusive rights under the Northern Patent Rights
(as defined) and Northern Know-How (as defined) in order to develop and commercialize Licensed Compounds (as defined) and Licensed Products (as defined); and 

WHEREAS, the Parties now desire to amend and restate the Prior Agreement in the form of this Agreement. 

NOW, THEREFORE, the Parties hereby agree as follows: 

Section 1. Definitions. 
 For the
purpose of this Agreement, the following words and phrases shall have the meanings set forth below: 
 1.1 “Affiliate” of an
entity means any other entity which (directly or indirectly) is controlled by, controls or is under common control with such entity. For the purposes of this definition, the term “control” (including, with correlative meanings, the terms
“controlled by” and “under common control with”) as used with respect to an entity means (i) in the case of a corporate entity, direct or indirect ownership of voting securities entitled to cast at least fifty percent
(50%) of the votes in the election of directors or (ii) in the case of a non-corporate entity, direct or indirect ownership of at least fifty percent 50%) of the equity interests with the power to direct the management and policies of such
entity, provided that if local law restricts foreign ownership, control shall be established by direct or indirect ownership of the maximum ownership percentage that may, under such local law, be owned by foreign interests. 

1.2 “Confidential Information” means all Technology, chemical or biological materials, marketing plans, strategies and
customer lists, and other information that are disclosed or provided by such Party or its Affiliates to the other Party or its Affiliates, regardless of whether any of the foregoing are marked “confidential” or “proprietary” or
communicated to the other by the disclosing Party or its Affiliates in oral, written, graphic, or electronic form. 
 1.3
“Confidentiality Agreement” means that certain Confidential Disclosure Agreement, dated [***], by and between Northern and Spero Therapeutics, Inc. 

1.4 “Controlled” or “Controls”, when used in reference to patent or other intellectual property rights or
Technology, means the legal authority or right of a person or entity to grant a license or sublicense of intellectual property rights to another person or entity, or to otherwise disclose or provide Technology to such other person or entity, without
breaching the terms of any agreement with a different person or entity. 

  
 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. 

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 1.5 “Improvements” means all Technology that amount to improvements to any
of the inventions related to the Licensed Compounds and claimed by the Northern Patent Rights or to the Northern Know-How related to the Licensed Compounds and made, developed, conceived, owned or otherwise Controlled by Northern or any of its
Affiliates after the date hereof, whether or not patentable or patented. 
 1.6 “Licensed Compound” means (a) the
compounds described in Exhibit A and (b) any [***] of any compounds covered by the foregoing clause (a) or this clause (b). 

1.7 “Licensed Product” means any pharmaceutical product containing a Licensed Compound (alone or with other active
ingredients), in all forms, presentations, formulations and dosage forms. 
 1.8 “Northern Know-How” means all Technology,
now existing or hereafter arising during the time the license grant set forth in Section 2.1 is in effect, owned or otherwise Controlled by Northern or any of its Affiliates, that is related to the Northern Patent Rights and that is reasonably
necessary or useful for the manufacture, use, sale, offer for sale, importation, research, development or commercialization or other exploitation of any Licensed Compounds or Licensed Products or Improvements. Exhibit B attached hereto lists
specific Northern Know-How. 
 1.9 “Northern Patent Rights” means the patents and patent applications that claim any
Licensed Compounds, listed in Exhibit C attached hereto, and (a) any foreign counterparts thereof, (b) all divisionals, continuations, continuations-in-part thereof or any other patent application claiming priority directly or
indirectly to (i) any of the patents or patent applications identified on Exhibit C or (ii) any patent or patent application from which the patents or patent applications identified on Exhibit C claim direct or indirect
priority, and (c) all patents issuing on any of the foregoing, and any foreign counterparts thereof, together with all registrations, reissues, reexaminations, renewals, supplemental protection certificates, or extensions of any of the
foregoing, and any foreign counterparts thereof, plus the Northern Improvement Patents. For avoidance of any doubt, Northern Patent Rights do also claim or cover other compounds than Licensed Compounds (hereafter called as “Other
Compounds”). Furthermore, Northern may in the future also have patent applications or patents that claim or cover Other Compounds only, i.e. no Licensed Compounds at all, such patent applications and patents being totally excluded from Northern
Patent Rights and consequently also from Exhibit C. 
 1.10 “Northern Improvement Patents” means all patents and
patent applications owned or otherwise Controlled by Northern during the term of this Agreement that claim any Improvements or their manufacture or use, which shall be listed in Exhibit C as contemplated by Section 5.1. 

1.11 “Technology” means know-how, trade secrets, chemical and biological materials, formulations, information, documents,
studies, results, data and regulatory approvals, filings and correspondence (including DMFs), including biological, chemical, pharmacological, toxicological, pre-clinical, clinical and assay data, manufacturing processes and data, specifications,
sourcing information, assays, and quality control and testing procedures, whether or not patented or patentable. 
  

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. 

  
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 1.12 “Third Party” means any person or entity other than Spero or Northern
or any of their Affiliates. 
 Section 2. License Grants by Northern. 

2.1 Exclusive License. Northern, for itself and on behalf of its Affiliates, hereby grants to Spero a non-transferable (except in
accordance with Section 9.1), exclusive (even as to Northern and its Affiliates), worldwide license, with the right to sublicense in accordance with Section 2.2, under the Northern Patent Rights and Northern Know-How, to make, have made,
use, sell, offer to sell, import, research, develop, commercialize and otherwise exploit Licensed Compounds and Licensed Products and Improvements. For avoidance of any doubt, it is understood and accepted that Northern Patent Rights and Northern
Know-How also claim, cover or relate to Other Compounds, and that this Exclusive License to Spero does not include any rights whatsoever to said Other Compounds. Nothing in this Agreement prevents Northern from granting to Third Parties, on an
exclusive and worldwide basis, Northern Patent Rights, Northern Know-How or Improvements claiming, covering or related to Other Compounds (but unequivocally excluding any rights whatsoever to any and all Licensed Compounds), without any obligations
whatsoever to Spero or its Affiliates. 
 2.2 Sublicenses. The licenses granted in Section 2.1 include the right to grant
sublicenses (through multiple tiers) to sublicensees (each, a “Sublicensee”); provided that Spero shall remain responsible for the performance of its Sublicensees hereunder. Spero shall provide Northern with a copy of the sublicense
agreement for its Sublicensees within [***] of execution, which copy shall be treated as Confidential Information of Spero hereunder. 
 2.3
Consideration. As remuneration for the exclusive license under Section 2.1: 
 (a) Spero will pay to Northern up to an aggregate
of $2,500,000 (the “Near Term Milestone Payment”) in one or more payments upon achievement of the “Near Term Milestone Events” as follows, regardless of whether the relevant Near Term Milestone Events listed below are achieved by
Spero, one of its Affiliates or a Sublicensee: 
  

					
	 	 	 Near Term Milestone Event
	  	Near Term Milestone
Payment Amount
	1	 	[***] if no more than one Near Term Milestone Event has previously been achieved but the aggregate Near Term Milestone Payment paid or payable at such time is $[***].	  	$[***]
			
	2	 	[***] if no more than one Near Term Milestone Event has previously been achieved but the aggregate Near Term Milestone Payment paid or payable at such time is $[***].	  	$[***]
			
	3	 	[***] and no other Near Term Milestone Event has previously been achieved.	  	$[***]

  

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. 

  
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	4	 	Within [***] days after the closing of an IPO by Spero (or an Affiliate of Spero or any successor to Spero or its Affiliate) if no other Near Term Milestone Event has previously been achieved.	  	2,500,000
			
	5	 	Within [***] days after the closing of an IPO by Spero (or an Affiliate of Spero or any successor to Spero or its Affiliate) if no more than one Near Term Milestone Event has previously been achieved but the aggregate Near Term
Milestone Payment paid or payable at such time is $1,250,000.	  	$1,250,000

 For clarity, each Near Term Milestone Payment is payable only once, regardless of the number of Combination Products that
achieve the relevant Near Term Milestone Event or the number of times a Combination Product achieves such Near Term Milestone Event, and in no event will aggregate Near Term Milestone Payments exceed $2,500,000. 

(b) Spero will, in addition to the Near Term Milestone Events, pay to Northern an aggregate of $4,500,000 (the “Marketing Milestone
Payment”) upon receipt of Marketing Approval for a Combination Product, regardless of whether the Marketing Approval is achieved by Spero, one of its Affiliates or a Sublicensee. 

(c) As used in this Section 2.3, the following terms shall have the following respective meanings: 

“Combination Product” means any product, process or service which incorporates one or more therapeutically active ingredients,
other than a Licensed Compound, in combination or co-formulation, regardless whether administered separately or together, with a Licensed Compound.  

“IPO” means either (i) the initial public offering by Spero Therapeutics, LLC (or any other Affiliate of Spero, or any
successor to Spero or its Affiliate) of its or its Affiliate’s securities (or their successor’s securities), or (ii) [***]. 

“Marketing Approval” means, with respect to a Combination Product, in a particular jurisdiction, the receipt of all approvals,
licenses, registrations or authorizations necessary for the sale and marketing of such Combination Product in such jurisdiction, including, with respect to the United States, approval of NDA for such Combination Product by the FDA. For clarity,
Marketing Approval does not include reimbursement authorization or pricing approval determinations. 
 “Phase II Clinical
Trial” means human clinical study or trial generally described in 21 CFR § 312.21(b), as amended (or its successor regulation or comparable laws in countries outside of the United States), that is intended to support a preliminary
determination as to whether a product is safe for its intended use, and to provide preliminary information about such product’s efficacy, in order to permit the design of further trials. 

“Phase III Clinical Trial” means human clinical study or trial generally described in 21 CFR § 312.21(c), as amended (or
its successor regulation or comparable laws in countries outside of the United States). 
 “Phase II/III Clinical Trial”
means a planned combined phase II/III human clinical study or trial (Tier B Pathway), or if such combined clinical trial is not performed as planned, any clinical trial generally described in 21 C.F.R. §312.21(b), as amended or succeeded, or,
with respect to a jurisdiction other than the United States, an equivalent clinical trial, that is intended to (i) serve as a primary basis for establishing that a product is safe and efficacious for its intended use, (ii) provide an adequate basis
to establish physician labeling, including, contraindications, warnings, precautions and adverse reactions and (iii) support marketing approval for such product. 
  

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. 

  
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 Section 3. Transfer of Northern Know-How. 

3.1 Documentation. During the [***] period following the Initial Effective Date, Northern shall provide to Spero one (1) electronic
copy of all documents, data or other information in Northern’s or its Affiliates’ possession or control as of the Initial Effective Date to the extent that such documents, data and information describe or contain Northern Know-How.
Northern shall provide and transfer to Spero in the same manner all additional Northern Know-How that may from time to time become available to Northern (and in any event at least semi-annually), including that concerning any Improvements. 

3.2 Technical Assistance. Northern shall reasonably collaborate with Spero in the further development of the Licensed Compounds. Such
collaboration shall include Northern providing Spero with reasonable access by teleconference or in-person at Northern’s facilities to Northern personnel who have been involved in the research and development of the Licensed Compounds to
provide Spero with a reasonable level of technical assistance and consultation in connection with the transfer of Northern Know-How. 
 Section 4.
Development and Commercialization; Joint Steering Committee. 
 4.1 Responsibilities and Costs. Spero shall have sole
responsibility for, and shall bear all its costs of conducting, all development and commercialization of Licensed Compounds and Licensed Products (including manufacturing all required materials and filing for and obtaining all required regulatory
approvals). Spero shall own the results of all such activities, and as between the Parties, all such regulatory approvals shall be obtained by and in the name of Spero (or its Affiliates or Sublicensees). 

4.2 Reporting. Spero shall provide to Northern a written report for each calendar quarter, which shall adequately describe the status of
the development and commercialization of the Licensed Compounds and Licensed Products (including for the avoidance of doubt any Combination Product), including at a minimum: results and data of any clinical or non-clinical studies and [***]. All
such reports and their contents shall constitute Confidential Information of Spero. 
 4.3 Joint Steering Committee. Promptly
following the Effective Date, the Parties shall establish a joint steering committee (the “JSC”) to provide for the exchange of information and ideas regarding the continued research and development of the Licensed Compounds, to plan and
monitor the conduct of such research and activities during the Term and to provide and receive updates regarding the invention or development of any Improvements. The JSC shall not have any decision-making authority and is not authorized to [***] or
to [***]. Each of the Parties shall designate in writing [***] representatives to the JSC. Each Party shall have the right at any time to substitute individuals, on a permanent or temporary basis, for any of its previously designated representatives
to the JSC by giving written notice to the other Party. The JSC shall establish a schedule of times for regular meetings to be conducted by teleconference or in person as it shall determine. The Parties shall each bear all expenses of their
respective JSC representatives related to their participation on the JSC and attendance at JSC meetings; provided that if Spero reimburses any of its, or its Affiliates, officers, directors or employees for such participation it shall so notify
Northern and it shall reimburse Northern for the participation of any of its, or its Affiliates, officers, directors or employees for such participation on the same terms. 
  

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. 

  
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 Section 5. Patent Prosecution, Infringement and Extensions. 

5.1 Appointment and Cooperation. With respect to all of the rights and activities of Spero set forth in this Section 5, Northern
hereby appoints Spero as its agent for such purposes with the authority to act on Northern’s behalf with respect to the Northern Patent Rights. Northern shall cooperate with Spero in the exercise of Spero’s authority granted herein, and
shall execute such documents and take such additional action as Spero may request in connection therewith. The Parties shall promptly update Exhibit C to list all Northern Patent Rights (including Northern Improvement Patents). 

5.2 Prosecution and Maintenance. 

(a) By Spero. Within [***] of the Effective Date, Northern shall mandate its patent attorneys ([***], and [***]) to provide Spero, at
Spero’s cost, with copies of the complete prosecution files for all patents and patent applications listed on Exhibit C. Spero shall be solely responsible for the preparation, prosecution (including any interferences, oppositions,
reissue proceedings and reexaminations) and maintenance of the Northern Patent Rights, and all filing, prosecution, and maintenance decisions with respect to the Northern Patent Rights shall be made by Spero, provided Northern shall retain the right
to give comments to Spero on material aspects of those activities. Spero shall be responsible for all its costs incurred for such preparation, prosecution and maintenance. Each Party shall provide to the other Party copies of any papers relating to
the filing, prosecution or maintenance of Northern Patent Rights promptly upon receipt. Northern shall not take any action with respect to the prosecution or maintenance of any Northern Patent Rights without the prior written consent of Spero,
except as contemplated by Section 5.2(b). In addition to the foregoing, promptly following the Effective Date, Spero and Northern shall use reasonable best efforts to work together to prepare and file, where permitted under applicable laws and
regulations, continuation applications, divisional applications or such other applications or filings related to the Northern Patent Rights that claim solely Other Compounds and their uses (such applications or filings and any patents issuing
therefrom are the “OC Patents”). Spero shall pay the first [***] dollars ($[***]) in out-of-pocket expenses incurred in connection with the preparation and filing of such patent applications and filings and thereafter the Parties shall
[***] such costs and expenses. The OC Patents shall not be included in the Northern Patent Rights for any other purposes under this Agreement. For avoidance of doubt, as between the Parties, Northern and its designees shall have sole authority to
pursue the further prosecution, maintenance and enforcement of the OC Patents. Furthermore, in an identical fashion, following the Effective Date, Spero and Northern shall use reasonable best efforts to work together, at Spero’s sole expense,
to prepare and file, where permitted under applicable laws and regulations, continuation applications, divisional applications or such other applications or filings related to the Northern Patent Rights that do not claim any Other Compounds or their
uses (such applications or filings and any patents issuing therefrom are the “SC Patents”. For avoidance of doubt, as between the Parties, Spero and its designees shall have sole authority to pursue the further prosecution, maintenance and
enforcement of the SC Patents. 
  
 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. 

  
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 (b) By Northern. Spero shall not knowingly permit any of the Northern Patent
Rights to be abandoned in any country or their scope to be unreasonably limited (for example, to exclude Other Compounds) without Northern first being given an opportunity to assume full responsibility for the continued prosecution and maintenance
of same. In the event that Spero decides not to continue the prosecution or maintenance of a patent application or patent within Northern Patent Rights in any country, Spero shall provide Northern with notice of this decision at least [***] prior to
any pending lapse or abandonment thereof. Northern shall have the right to assume control of the continued prosecution or maintenance of any such patent application or patent (excluding any SC Patents) provided that Northern shall, if so requested
by Spero, take such actions as may be reasonably requested by Spero to amend such patent applications or patents, to the extent feasible under applicable laws and regulations, to narrow the scope thereof so that such patent applications and patents
no longer claim Licensed Compounds if such amendment is feasible without excluding Other Compounds from being so claimed. In the event that Northern elects to assume responsibility for such prosecution and maintenance within [***] of Spero’s
notice, Section 5.2(a) shall thereafter apply to such patent application(s) and patent(s) except that the role of Spero and Northern shall be reversed thereunder, including that Northern shall be solely responsible for all costs arising from
those activities and hence it shall be also deemed that the exclusive, even as to Spero, rights to said patent(s) and patent application(s) return to the full discretion of Northern and Northern shall redeem all its rights back to its ownership with
the purchase price of one US dollar. 
 5.3 Enforcement and Defense. In the event that Northern or Spero becomes aware of a
suspected infringement of any Northern Patent Right, or any such Northern Patent Right is challenged in any action or proceeding (other than any interferences, oppositions, reissue proceedings or reexaminations, which are addressed above), such
Party shall notify the other Party promptly, and following such notification, the Parties shall confer. Except as otherwise provided below, Spero shall have the right, but shall not be obligated, to defend any such action or proceeding or bring an
infringement action with respect to such infringement at its own expense, in its own name and entirely under its own direction and control, or settle any such action or proceeding by sublicense; provided that, if there exists an issued SC Patent to
serve as the basis of the infringement action in connection with such Third Party activities, Spero will limit its enforcement action to such SC Patent if so doing does not materially decrease Spero’s likelihood of success. Prior to initiating
an enforcement action that uses a Northern Patent Right other than an SC Patent as the basis for the claim of infringement, Spero shall meet with Northern to discuss ways to manage the potential risk to such Northern Patent Right in connection with
such enforcement action, including limiting the number and scope of claims that are asserted in connection with such action. Spero shall use good faith efforts to employ any reasonable measures agreed to by the Parties to manage such potential risk.
Northern shall reasonably assist Spero in any action or proceeding being defended or prosecuted if so requested, and shall join such action or proceeding if reasonably requested by Spero or required by applicable law at Spero’s expense. After
Spero has recovered an amount equal to the cost it incurred in connection with any such action or proceeding, any remaining and received amounts of compensation and/or damages paid by a third party as awarded to Spero due to the above action or
proceeding shall be shared [***] percent ([***]%) to Spero and [***] percent ([***]%) to Northern. With respect to infringements arising out of the activities of a Third Party with a compound that is an Other Compound, Northern shall have the right,
but shall not be obligated, to defend any such action or proceeding or bring an infringement action with respect to 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. 

  
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infringement at its own expense, in its own name and entirely under its own direction and control, or settle any such action or proceeding by sublicense; provided that, if there exists an issued
OC Patent to serve as the basis of the infringement action in connection with such Third Party activities, Northern will limit its enforcement action to such OC Patent if so doing does not materially decrease Northern’s likelihood of success
and the roles of the Parties under this Section 5.3 shall be reversed, solely with respect to such action. Prior to initiating an enforcement action that uses a Northern Patent Right other than an OC Patent as the basis for the claim of
infringement, Northern shall meet with Spero to discuss ways to manage the potential risk to such Northern Patent Right in connection with such enforcement action, including limiting the number and scope of claims that are asserted in connection
with such action. Northern shall use good faith efforts to employ any reasonable measures agreed to by the Parties to manage such potential risk. 

5.4 Patent Extensions; Orange Book Listings; Patent Certifications. 

(a) Patent Term Extension. If elections with respect to obtaining patent term extension or supplemental protection certificates
or their equivalents in any country with respect to Northern Patent Rights or other patent rights covering Licensed Products or their manufacture or use are available, Spero shall have the sole right to make any such elections. In case Spero decides
not to make such election with respect to a Licensed Product, Northern has the right but no obligation to do so in its own name and at its own expense with respect to a product containing an Other Compound (but not with respect to a Licensed
Product). 
 (b) Data Exclusivity and Orange Book Listings. With respect to data exclusivity periods (such as those
periods listed in the FDA’s Orange Book (including any available pediatric extensions) or periods under national implementations of Article 10.1(a)(iii) of Directive 2001/EC/83, and all equivalents in any country), Spero shall have the sole
right to seek and maintain all such data exclusivity periods available for the Licensed Products. 
 (c) Notification of
Patent Certification. Northern shall notify and provide Spero with copies of any allegations of alleged patent invalidity, unenforceability or non-infringement of a Northern Patent Right pursuant to a Paragraph IV Patent Certification by a Third
Party filing an Abbreviated New Drug Application, an application under §505(b)(2) or any other similar patent certification by a Third Party, and any foreign equivalent thereof. Such notification and copies shall be provided to Spero within
[***] after Northern receives such certification, and shall be sent to the address set forth in Section 9.4. 
 Section 6. Confidential
Information and Publicity. 
 (a) Confidential Information. Except as expressly provided herein, each of the Parties agrees
that, for itself and its Affiliates, and for as long as this Agreement is in effect and for a period of [***] years thereafter, a Party and its Affiliates (the “Receiving Party”) receiving Confidential Information of the other Party or its
Affiliates (the “Disclosing Party”) shall (i) not disclose such Confidential Information to any Third Party without the prior written consent of the Disclosing Party, except for disclosures expressly permitted below, and (ii) not
use such Confidential Information for any purpose except those licensed or otherwise authorized or permitted by this Agreement. For clarity, all Confidential Information of Spero received by or disclosed to Northern hereunder shall be used by
Northern only for ensuring that Spero complies with its obligations hereunder and for no other purposes. 
  

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. 

  
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 (b) Exceptions. The obligations in Section 6.1(a) shall not apply with
respect to any portion of the Confidential Information that the Receiving Party can show by competent proof: 
 (i) is
publicly disclosed by the Disclosing Party, either before or after it is disclosed to the Receiving Party hereunder; 
 (ii)
was known to the Receiving Party or any of its Affiliates, without any obligation to keep it confidential or any restriction on its use, prior to disclosure by the Disclosing Party; 

(iii) is subsequently disclosed to the Receiving Party or any of its Affiliates by a Third Party lawfully in possession thereof
and without any obligation to keep it confidential or any restriction on its use; 
 (iv) is published by a Third Party or
otherwise becomes publicly available or enters the public domain, either before or after it is disclosed to the Receiving Party; or 

(v) has been independently developed by employees or contractors of the Receiving Party or any of its Affiliates without the
aid, application or use of Confidential Information of the Disclosing Party. 
 (c) Authorized Disclosures. The Receiving Party
may disclose Confidential Information belonging to the Disclosing Party to the extent (and only to the extent) such disclosure is reasonably necessary in the following instances: 

(i) subject to Section 6.2, by either Party in order to comply with applicable non-patent law (including any securities
law or regulation or the rules of a securities exchange) and with judicial process, if in the reasonable opinion of the Receiving Party’s counsel, such disclosure is necessary for such compliance; 

(ii) by either Party, in connection with prosecuting or defending litigation, making regulatory filings, and filing,
prosecuting and enforcing patent applications and patents; 
 (iii) by Spero, to its Affiliates, potential and future
collaborators (including Sublicensees), permitted acquirers or assignees under Section 9.1, research collaborators, subcontractors, investment bankers, investors, lenders, and their and each of Spero and its Affiliates’ respective
directors, employees, contractors and agents; and 
 (iv) by Northern to its Affiliates, permitted acquirers or assignees
under Section 9.1, investment bankers, investors, lenders, and their and Northern and its Affiliates’ respective directors, employees, contractors and agents, 
  

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. 

  
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 provided that (1) with respect to Section 6.1(c)(i) or 6.1(c)(ii), where reasonably possible, the
Receiving Party shall notify the Disclosing Party of the Receiving Party’s intent to make any disclosure pursuant thereto sufficiently prior to making such disclosure so as to allow the Disclosing Party adequate time to take whatever action it
may deem appropriate to protect the confidentiality of the information to be disclosed, and (2) with respect to Sections 6.1(c)(iii) and 6.1(c)(iv), each of those named people and entities must be bound prior to disclosure by confidentiality
and non-use restrictions at least as restrictive as those contained in this Section 6 (other than investment bankers, investors and lenders, who must be bound prior to disclosure by commercially reasonable obligations of confidentiality). In
addition to the foregoing, Spero and its Affiliates and Sublicensees may make such disclosures of Northern Know-How specifically concerning the Licensed Compound and its use as any of them may deem reasonably necessary for their business. 

6.2 Terms of this Agreement; Publicity. The Parties agree that the terms of this Agreement shall be treated as Confidential Information
of both Parties, and thus may be disclosed only as permitted by Section 6.1(c), with the exception, however, that, in order to comply with the stipulations in the Sections 5.2 through 5.4 of this Agreement, Northern shall be allowed to disclose
the terms of this Agreement to bone fide potential licensee of the Northern Patent Rights covering Other Compounds. Each Party agrees not to issue any press release or other public statement disclosing information relating to this Agreement or the
transactions contemplated hereby or the terms hereof without the prior written consent of the other Party or as permitted by Section 6.1(c). 

6.3 Relationship to the Confidentiality Agreement. This Agreement supersedes the Confidentiality Agreement, provided that all
“Confidential Information” disclosed or received by the Parties thereunder shall be deemed “Confidential Information” hereunder and shall be subject to the terms and conditions of this Agreement. 

Section 7. Warranties; Limitations of Liability; Indemnification 

(a) Northern Representations and Warranties. Northern covenants, represents and warrants to Spero that as of the Effective Date (unless
another date is set forth below): Northern is a corporation duly organized, validly existing and in good standing under the laws of state or jurisdiction in which it is incorporated, and it has full right and authority to enter into this Agreement
and to grant the licenses and other rights to Spero as herein described. 
 (b) This Agreement has been duly authorized by all requisite
corporate action, and when executed and delivered will become a valid and binding contract of Northern enforceable against Northern in accordance with its terms, subject to applicable bankruptcy, insolvency, reorganization, moratorium and other law
affecting creditors’ rights generally from time to time if effect, and to general principles of equity. 
 (c) The execution, delivery
and performance of this Agreement does not conflict with any other agreement, contract, instrument or understanding, oral or written, to which Northern is a party, or by which it is bound, nor will it violate any law applicable to Northern. 

 
 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. 

  
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 (d) All necessary consents, approvals and authorizations of all regulatory and governmental
authorities and other persons or entities required to be obtained by Northern in connection with the execution and delivery of this Agreement and the performance of its obligations hereunder have been obtained. 

(e) Attached hereto as Exhibit C is a complete and accurate list of all patents and patent applications owned (in whole or in part) or
otherwise Controlled by Northern or any of its Affiliates that the manufacture, use, sale, offer for sale or importation of any Licensed Compounds would infringe on the Initial Effective Date. To the knowledge of Northern on the Initial Effective
Date, the issued claims included in the Northern Patent Rights were valid and enforceable, and no written claim had been made (except by a patent examiner during prosecution of the patent application(s) that resulted in any such issued patent
claims), and no action or proceeding had been commenced or threatened, alleging to the contrary. Northern was on the Initial Effective Date and the Effective Date, the sole and exclusive owner of all right, title and interest in and to the Northern
Patent Rights. None of the Northern Patent Rights or Northern Know-How was on the Initial Effective Date or Effective Date, subject to any lien, security interest or other encumbrance created by Northern. To Northern’s knowledge on the Initial
Effective Date, the conception and reduction to practice of the Northern Patent Rights have not constituted or involved the misappropriation of trade secrets or other rights or property of any Third Party. There were on the Initial Effective Date,
no claims, judgments or settlements against or amounts with respect thereto owed by Northern or any of its Affiliates relating to the Northern Patent Rights. To Northern’s knowledge on the Initial Effective Date, there has been no infringement
by any Third Party of any Northern Patent Rights. Apart from the financial obligations listed in Exhibit D, the use or practice of the license grants contained in Section 2 shall not trigger any payment obligation by Northern or any of
its Affiliates to any Third Party. 
 (f) On the Initial Effective Date, there was no pending action or proceeding alleging, or, to
Northern’s knowledge on the Initial Effective Date, any written communication alleging, that the manufacture, use, sale, offer for sale or importation of any Licensed Compounds, the activities of Northern or any of its Affiliates or any of
their licensees with respect to any such Licensed Compounds, or the practice or use of the Northern Patent Rights or Northern Know-How, had or would infringe or misappropriate any patent or other intellectual property rights of any Third Party.
Northern had on the Initial Effective Date notified Spero of all such rights of any Third Party of which Northern was aware that are related to the foregoing activities. 

(g) On the Initial Effective Date, Northern did not have any knowledge of any scientific or clinical facts or circumstances that would
materially and adversely affect the safety, efficacy or market performance of any Licensed Compounds that had not been communicated to Spero. 

(h) Northern covenants that it will provide prompt written notice to Spero if Northern receives or sends any notice relating to an actual or
purported breach of that certain Intellectual Property Rights Purchase Agreement between [***] and Northern dated on or about [***], or if Northern becomes aware of any reasonable basis for such a claim. 

 
 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. 

  
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 7.2 Spero Representations and Warranties. Spero covenants, represents and warrants to
Northern that as of the Effective Date: 
 (a) Spero is a corporation duly organized, validly existing and in good standing under the laws of
state in which it is incorporated, and it has full right and authority to enter into this Agreement and to accept the rights and licenses granted as herein described. 

(b) This Agreement has been duly authorized by all requisite corporate action, and when executed and delivered will become a valid and binding
contract of Spero enforceable against Spero in accordance with its terms, subject to applicable bankruptcy, insolvency, reorganization, moratorium and other laws affecting creditors’ rights generally from time to time if effect, and to general
principles of equity. 
 (c) The execution, delivery and performance of this Agreement does not conflict with any other agreement, contract,
instrument or understanding, oral or written, to which Spero is a party, or by which it is bound, nor will it violate any law applicable to Spero. 

(d) All necessary consents, approvals and authorizations of all regulatory and governmental authorities and other persons or entities required
to be obtained by Spero in connection with the execution and delivery of this Agreement and the performance of its obligations hereunder have been obtained. 

(e) Spero covenants that it will [***] to make commercial use of the Northern Patent Rights and to prosecute, maintain and/or defend the
Northern Patent Rights in accordance with bona fide strategic reasons intended to support the development and commercialization of the Licensed Products and not otherwise for the benefit of any Third Parties. 

7.3 DISCLAIMER. EXCEPT AS PROVIDED IN SECTION 7.1, NORTHERN, TO THE FULLEST EXTENT PERMITTED BY LAW, EXPRESSLY DISCLAIMS ALL WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF THE MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, SAFETY, EFFICACY, APPROVABILITY BY REGULATORY AUTHORITIES, TIME AND COST OF DEVELOPMENT, PATENTABILITY AND/OR BREADTH OF
THE PATENT COVERAGE, AND INFRINGEMENT. EXCEPT AS PROVIDED IN SECTION 7.1, NORTHERN MAKES NO WARRANTY, EITHER EXPRESS OR IMPLIED, WITH RESPECT TO THE LICENSED COMPOUNDS OR LICENSED PRODUCTS. 

7.4 Indemnification. Except to the extent arising out of a breach of this Agreement by Northern or the gross negligence or intentional
misconduct of an Indemnitee, Spero shall indemnify, defend and hold harmless Northern and its directors, officers, employees, agents and the successors and assignees of any of the foregoing (collectively, the “Indemnitees”) from and
against any and all judgments, out of pocket losses, expenses, actual damages and/or liabilities (including, without limitation, any and all reasonable attorney’s fees), that an Indemnitee may incur from any and all Third Party claims, suits,
actions and/or proceedings arising out of, relating to, or incidental to the design, manufacture, distribution or use of Licensed Compounds or Licensed Products. This indemnification obligation shall be limited as and to the extent 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. 

  
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an Indemnitee failure to give prompt written notice of such a Third Party claim, suit, action and/or proceeding to Spero causes the loss of a defense that otherwise would have been available in
connection with such Third Party claim, suit, action and/or proceeding. Spero shall control the defense of any such Third Party claims, suits, actions and/or proceedings. 

Section 8. Term, Termination and Survival. 

8.1 Term. This Agreement shall commence as of the Effective Date and the license grants contained in Section 2 are perpetual,
irrevocable and fully paid up. 
 8.2 Survival. The following provisions shall survive expiration or termination of this Agreement for
any reason, as well as any other provision which by its terms or by the context thereof, is intended to survive such termination: Sections 6, 7, 8 and 9. Expiration or termination of this Agreement for any reason shall not relieve the Parties of any
liability or obligation which accrued hereunder prior to the effective date of such termination or expiration, nor preclude either Party from pursuing all rights and remedies it may have hereunder or at law or in equity, subject to Section 9.5,
with respect to any breach of this Agreement nor prejudice either Party’s right to obtain performance of any obligation. 
 Section 9. General
Provisions. 
 9.1 Assignment. Neither Party may assign this Agreement without the prior written consent of the other Party, which
consent shall not be unreasonably withheld; provided that either party may transfer or assign this Agreement, in whole or in part, to an Affiliate, or in connection with a merger, consolidation, or a sale or transfer of all or substantially all of
the assets to which this Agreement relates, provided that all obligations of such party are assumed by the assignee. Any assignment or transfer in violation of this Section 9.1 shall be void. This Agreement shall inure to the benefit of, and be
binding upon, the legal representatives, successors and permitted assigns of the Parties. In the event that [***], Spero or any of its Affiliates or successors, is acquired [***], the Parties agree that if, at the time of such acquisition, Spero, or
any of its Affiliates or successors, is continuing to research, develop or commercialize one or more Licensed Compounds or Licensed Products, then [***]. 

9.2 Severability. If any one or more of the provisions contained in this Agreement is held invalid, illegal or unenforceable in any
respect, the validity, legality and enforceability of the remaining provisions contained herein shall not in any way be affected or impaired thereby, unless the absence of the invalidated provision(s) adversely affects the substantive rights of the
Parties. The Parties shall in such an instance use their reasonable best efforts to replace the invalid, illegal or unenforceable provision(s) with valid, legal and enforceable provision(s) which, insofar as practical, implement the purposes of this
Agreement. 
 9.3 Amendment; Waiver. This Agreement may not be modified, amended or rescinded, in whole or part, except by a written
instrument signed by the Parties; provided that any unilateral undertaking or waiver made by one Party in favor of the other shall be enforceable if undertaken in a writing signed by the Party to be charged with the undertaking or waiver. No delay
or omission by either Party hereto in exercising any right or power occurring upon any noncompliance or default by the other Party with respect to any of the terms of this Agreement 

 
 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. 

  
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shall impair any such right or power or be construed to be a waiver thereof. A waiver by either of the Parties of any of the covenants, conditions or agreements to be performed by the other shall
not be construed to be a waiver of any succeeding breach thereof or of any other covenant, condition or agreement herein contained. 
 9.4
Notices. Except as otherwise provided herein, all notices under this Agreement shall be sent by certified mail or by overnight courier service, postage prepaid, to the following addresses of the respective Parties: 

 

			
	 If to Spero, to:
	  	Spero Potentiator, Inc.
		  	675 Massachusetts Avenue, 14th floor
		  	Cambridge, MA 02139
		  	Attention: Chief Executive Officer
		
	 With a required copy to:
	  	Mintz Levin
		  	One Financial Center, 40th Floor
		  	Boston, MA 02111
		  	Attention: Lewis Geffen, Esq.
		
	 If to Northern, to:
	  	Northern Antibiotics Oy (Ltd.)
		  	Tekniikantie 14 (Technopolis, Innopoli 2) A111
		  	FIN-02150 Espoo, Finland
		  	Attention: Martti Vaara
		
	 With a required copy to:
	  	Borenius Attorneys Ltd
		  	Eteläesplanadi 2
		  	FIN-00130 Helsinki Finland
		  	Attention: Ben Rapinoja

 or to such address as each Party may hereafter designate by notice to the other Party. A notice shall be deemed to have been
given on the date it is received by all required recipients for the noticed Party. 
 9.5 Dispute Resolution. Disputes arising under
or in connection with this Agreement shall be resolved pursuant to this Section 9.5; provided, however, that in the event a dispute cannot be resolved without an adjudication of the rights or obligations of a Third Party, the dispute procedures
set forth in this Section 9.5 shall be inapplicable as to such dispute. 
 (a) In the event of a dispute between the Parties, the
Parties shall first attempt in good faith to resolve such dispute by negotiation and consultation between themselves. In the event that such dispute is not resolved on an informal basis within [***], any Party may, by written notice to the other,
have such dispute referred to each of the Parties’ respective CEOs or his or her designee (who shall be a senior executive), who shall attempt in good faith to resolve such dispute by negotiation and consultation for a [***] period following
receipt of such written notice. 
  
 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. 

  
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 (b) In the event the Parties’ CEOs (or designees) are not able to resolve such dispute,
either Party may at any time after such [***] period submit such dispute to be finally settled by arbitration administered in accordance with the Commercial Arbitration Rules of the American Arbitration Association (“AAA”) in effect at the
time of submission. The arbitration shall be heard and determined by three (3) arbitrators. Spero and Northern shall each appoint one arbitrator and the third arbitrator shall be selected by the two Party-appointed arbitrators, or, failing
agreement within [***] following the date of receipt by the respondent of the claim, by the AAA. Such arbitration shall take place in Boston, MA. The arbitration award so given shall be a final and binding determination of the dispute, shall be
fully enforceable in any court of competent jurisdiction. 
 (c) Costs of arbitration are to be divided by the Parties in the following
manner: Spero shall pay for the arbitrator it chooses, Northern shall pay for the arbitrator it chooses, and the costs of the third arbitrator shall be divided equally between the Parties. Except in a proceeding to enforce the results of the
arbitration or as otherwise required by law, neither Party nor any arbitrator may disclose the existence, content or results of any arbitration hereunder without the prior written consent of both Parties. 

9.6 Applicable Law. This Agreement shall be governed by and construed in accordance with the laws of the State of New York, without
regard to its conflicts of law provisions. 
 9.7 Further Assurances. Each Party agrees to do and perform all such further acts and
things and shall execute and deliver such other agreements, certificates, instruments and documents necessary or that the other Party may deem advisable in order to carry out the intent and accomplish the purposes of this Agreement and to evidence,
perfect or otherwise confirm its rights hereunder. 
 9.8 Relationship of the Parties. Each Party is an independent contractor under
this Agreement. Nothing contained herein is intended or is to be construed so as to constitute Northern and Spero as partners, agents or joint venturers. Neither Party shall have any express or implied right or authority to assume or create any
obligations on behalf of or in the name of the other Party or to bind the other Party to any contract, agreement or undertaking with any Third Party. There are no express or implied third party beneficiaries hereunder. 

9.9 Entire Agreement. Save for the certain Exchange Agreement entered into between the Parties on June 28, 2017, this Agreement
(along with the Exhibits) contains the entire understanding of the Parties with respect to the subject matter hereof and supersedes and replaces any and all previous arrangements and understandings, including the Confidentiality Agreement, whether
oral or written, between the Parties with respect to the subject matter hereof. 
 9.10 Headings. The captions to the several Sections
hereof are not a part of this Agreement, but are merely guides or labels to assist in locating and reading the several Sections hereof. 

9.11 Waiver of Rule of Construction. Each Party has had the opportunity to consult with counsel in connection with the review, drafting
and negotiation of this Agreement. Accordingly, the rule of construction that any ambiguity in this Agreement shall be construed against the drafting party shall not apply. 
  

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. 

  
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 9.12 Interpretation. Whenever any provision of this Agreement uses the term
“including” (or “includes”), such term shall be deemed to mean “including without limitation” (or “includes without limitations”). “Herein,” “hereby,” “hereunder,”
“hereof” and other equivalent words refer to this Agreement as an entirety and not solely to the particular portion of this Agreement in which any such word is used. All definitions set forth herein shall be deemed applicable whether the
words defined are used herein in the singular or the plural. Unless otherwise provided, all references to Sections and Exhibits in this Agreement are to Sections and Exhibits of this Agreement. 

9.13 Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of
which together shall constitute one and the same instrument. 
 [Remainder of this Page Intentionally Left Blank] 

 
 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. 

  
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Execution Version 
  

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

			
	NORTHERN ANTIBIOTICS OY (LTD.)
		
	By:	 	 /s/ Martti Vaara

		 	(Signature)
	Name:	 	Martti Vaara
	Title:	 	CEO
	Date:	 	June 28, 2017
	
	SPERO POTENTIATOR, INC.
		
	By:	 	 /s/ Ankit Mahadevia

		 	(Signature)
	Name:	 	Ankit Mahadevia
	Title:	 	Chief Executive Officer
	Date:	 	June 28, 2017

 SIGNATURE PAGE TO 

LICENSE AGREEMENT 
  

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 

Execution Version 
  

 EXHIBIT A 

LICENSED COMPOUNDS 
 Any and all
compounds [***] and claimed or covered by Northern Patent Rights (listed in Exhibit C). For avoidance of any doubt, Licensed Compounds include e.g. [***] and exclude Other Compounds such as e.g. [***]. 

 
 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. 

  
 Exhibit A-1 

 CONFIDENTIAL TREATMENT REQUESTED 

Execution Version 
  

 EXHIBIT B 

SPECIFIC NORTHERN KNOW-HOW 
 The
know-how in the documents below covers both Licensed Compounds and Other Compounds; for the purposes of this Agreement, only the know-how covering Licensed Compounds shall be regarded as Northern Know-How. 

Publications: 
 [***]. 

[***]. 
 [***]. 

[***] 
 [***]. 

[***]. 
 [***]. 

[***]. 
 [***]. 

[***]. 
 [***]. 

[***]. 
 Poster: 

[***] 
 [***]. 

Specific documents: 
 [***] 

[***] 
 [***] 

[***] 
  

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. 

  
 Exhibit B-1 

 CONFIDENTIAL TREATMENT REQUESTED 

 

			
	CONFIDENTIAL EXECUTION COPY	  	LICENSE AGREEMENT

  

 [***] 
 [***]

 [***] 
 [***] 

[***] 
 [***] 

 

			
	 Email messages sent to Spero:
  
	  	
	[***]	  	[***]
	[***]	  	[***]
	[***]	  	[***]
	[***]	  	[***]
	[***]	  	[***]
	[***]	  	[***]
	[***]	  	
	[***]	  	
	[***]	  	
	[***]	  	
	[***]	  	
	[***]	  	
	[***]	  	

  
 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. 

  
 Exhibit B-2 

 CONFIDENTIAL TREATMENT REQUESTED 

Execution Version 
  

 EXHIBIT C 

NORTHERN PATENT RIGHTS 
 For
avoidance of any doubt, it is understood and accepted that Northern Patent Rights claim, cover or relate to both Licensed Compounds and Other Compounds, and that the Exclusive License to Spero granted above does not include any rights whatsoever to
said Other Compounds. 
 Any and all patent applications and patents derived from [***]; 

currently including the patent applications [***], 
 [***], 

[***]; and 
 issued patents [***], 

[***]. 
  

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. 

  
 Exhibit C-1 

 CONFIDENTIAL TREATMENT REQUESTED 

Execution Version 
  

 EXHIBIT D 

FINANCIAL OBLIGATIONS 

See attached. 
  

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. 

  
 Exhibit D-1 

 CONFIDENTIAL TREATMENT REQUESTED 

 

			
	CONFIDENTIAL EXECUTION COPY	  	LICENSE AGREEMENT

  

 Northern Antibiotics Ltd 

Proprietary and confidential 
 IPR-related financial
obligations on Northern Antibiotics * 
  

							
	 Agreement
	  	 Partner
	  	 Effective

date
	  	 Financial obligation

	1 [***]	  	[***]	  	[***]	  	[***]
	2a [***]	  	[***]	  	[***]	  	[***]
	2b [***]	  	[***]	  	[***]	  	[***]
	3 [***]	  	[***]	  	[***]	  	[***]

  

	*	This is a summary to be used as general guidance only, and the agreements referred to herein above dominate this summary 

  

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. 

  
 Exhibit D-2EX-10.17

 Exhibit 10.17 

Spero Therapeutics, Inc. 

Proprietary Information and Inventions Assignment Agreement 

In consideration and as a condition of my employment, consultancy or other provision of services (“Service”) to SPERO THERAPEUTICS, INC. (the
“Company”) or any Affiliate thereof (the term “Affiliate” referring to any company related to Spero Therapeutics., Inc. (and collectively, “Affiliates”)), I agree as set forth below. 

 

 1. Proprietary Information. I agree that all information, whether or not in writing, concerning
the Company’s or its Affiliates’ business, technology, business relationships or financial affairs which the Company or its Affiliates have not released to the general public (other than due to any breach of this agreement) (collectively,
“Proprietary Information”) is and will be the exclusive property of the Company or its Affiliates, as applicable. By way of illustration, Proprietary Information may include information or material which has not been made generally
available to the public, such as: (a) corporate information, including plans, strategies, methods, policies, resolutions, negotiations or litigation; (b) marketing information, including strategies, methods, customer
identities or other information about customers, prospect identities or other information about prospects, or market analyses or projections; (c) financial information, including cost and performance data, debt arrangements, equity
structure, investors and holdings, purchasing and sales data and price lists; (d) operational and technological information, including plans, specifications, manuals, forms, templates, software, designs, procedures, formulas,
discoveries, inventions, improvements, concepts and ideas; and (e) personnel information, including personnel lists, reporting or organizational structure, resumes, personnel data, compensation structure, performance evaluations and
termination arrangements or documents. Proprietary Information also includes information received in confidence by the Company or its Affiliates from customers, suppliers or other third parties. 

2. Recognition of Company’s Rights. I will not, at any time, without the Company’s prior written permission, either during or after my
Service to the Company, disclose any Proprietary Information to anyone outside of the Company, or use or permit to be used any Proprietary Information for any purpose other than the performance of my duties in Service of the Company, and will
cooperate with the Company and use my best efforts to prevent the unauthorized disclosure of all Proprietary Information. This obligation of confidentiality will terminate five years after termination of my Service to the Company (and will survive
indefinitely for Proprietary Information that is a trade secret). I will deliver to the Company all copies of Proprietary Information in my possession or control reasonably promptly upon the earlier of a request by the Company or termination of my
Service of the Company. 
 3. Rights of Others. I understand that the Company and its Affiliates are now and may hereafter be subject to
non-disclosure or confidentiality agreements with third persons which require the Company and/or its Affiliates to protect or refrain from use of Proprietary Information. I agree to be bound by the terms of such agreements in the event I have access
to such Proprietary Information. 

 4. Commitment to Company; Avoidance of Conflict of Interest. While providing Service to the
Company, I will not knowingly engage in any business activity that conflicts with my duties to the Company and/or its Affiliates, and I will use my best efforts to comply with the Company’s and its Affiliates’ published policies and codes
of conduct and applicable law. I will advise the Board of Directors of the Company or its nominee at such time as I become aware that any activity of either the Company or its Affiliates or another business presents me with a conflict of interest or
the appearance of a conflict of interest as an employee or other service provider of the Company or its Affiliates. I will take whatever action is reasonably requested of me by the Company to resolve any conflict or appearance of conflict which it
finds to exist.  
 5. Developments. I will make full and prompt disclosure in writing to the Company of all inventions, discoveries,
designs, developments, methods, modifications, improvements, processes, algorithms, apparatuses, databases, computer programs, formulae, techniques, trade secrets, know-how, graphics or images, audio or visual works, software, software code and
other works of authorship (collectively “Developments”), whether or not patentable or copyrightable, that are created, made, conceived or reduced to practice by me (alone or jointly with others) or under my direction during the period of
my Service. I acknowledge and agree that all work performed by me is on a “work made for hire” basis, and I hereby do irrevocably assign and transfer, and will irrevocably assign and transfer, to the Company and its successors and assigns
all my right, title and interest in all Developments that (a) relate to the business of the Company, its Affiliates, or any customer of or supplier to the Company or any of its Affiliates or any of the products or services being researched,
developed or sold by the Company or its Affiliates, or which may be used with such products or services; (b) result from tasks assigned to me by the Company; or (c) result from the use of premises or personal property (whether tangible or
intangible) owned, leased or contracted for by the Company or any of its Affiliates (“Company-Related Developments”), and all related (i) patents, patent applications, patent disclosures, (ii) trademarks, service marks, trade
dress, trade names, logos, corporate names, internet domain names, and registrations and applications for the registration thereof together with all of the goodwill associated therewith, (iii) copyrights and copyright applications,
(iv) unregistered and registered design rights, (v) database rights and all other intellectual property and proprietary rights in all countries and territories worldwide and under any international conventions (“Intellectual Property
Rights”). 

 

 To preclude any possible uncertainty, I have set forth on Exhibit A attached hereto a
complete list of Developments that I have, alone or jointly with others, conceived, developed or reduced to practice prior to the commencement of my Service of the Company that I consider to be my property or the property of third parties and that I
wish to have excluded from the scope of this Agreement (“Prior Inventions”). I have also listed on Exhibit A all patents and patent applications in which I am named as an inventor, other than those which have been assigned to the
Company (“Other Patent Rights”). If no such disclosure is attached, I represent that there are no Prior Inventions or Other Patent Rights. If, in the course of my Service for the Company, I incorporate a Prior Invention into a Company
product, process or machine or other work done for the Company or its Affiliates, I hereby grant to the Company and its Affiliates (and their respective successors and assigns) a nonexclusive, royalty-free, paid-up, irrevocable, perpetual,
unrestricted, worldwide license (with the full right to sublicense) to make, have made, modify, offer for sale and import, use and sell such Prior Invention. Notwithstanding the foregoing, I will not incorporate, or permit to be incorporated, Prior
Inventions in any Company-Related Development without the Company’s prior written consent. 
 This Agreement does not obligate me to
assign to the Company any Development which, (a) is developed on my own time, does not relate to the business of the Company and is not based on or does not include Proprietary Information of the Company, and does not result from the use of
premises or equipment owned or leased by the Company, or (b) which relates to the business of an Affiliate and which I am obligated to assign to such Affiliate. However, I will also promptly disclose to the Company any such Developments for the
purpose of determining whether they qualify for such exclusion. I understand that to the extent this Agreement is required to be construed in accordance with the laws of any state which precludes a requirement in an employee agreement to assign
certain classes of inventions made by an employee, this paragraph 5 will be interpreted not to apply to any invention which a court rules and/or the Company agrees falls within such classes. I also hereby waive all claims to any moral rights or
other special rights which I may have or may accrue in any Company-Related Developments. 
 6. Documents and Other Materials. Should I develop
any Proprietary Information or Company-Related Developments during my Service to the Company, I will keep and maintain records of such information in a manner consistent with the Company’s business practices as set forth in the Company’s
written policies, which records will remain the sole property of, the Company or its Affiliates, as applicable. 
 All files, letters,
notes, memoranda, reports, records, data, sketches, drawings, notebooks, layouts, charts, quotations and proposals, specification sheets, or other written, photographic or other tangible material containing Proprietary Information, whether created
by me or others, which come into my custody or possession, are the exclusive property of the Company or its Affiliates, as applicable, to be used by me only in the performance of my duties for the Company. As used herein, “premises and personal
property 

 
owned, leased or contracted for by the Company or any of its Affiliates” shall not refer to or include any personal residence or personal property of mine. Any property situated on the
Company’s (or its Affiliates’) premises and owned by the Company (or its Affiliates), including, without limitation, computers, disks and other storage media, filing cabinets or other work areas, is subject to inspection by the Company at
any time with or without notice. In the event of the termination of my Service to the Company for any reason, I will deliver to the Company all files, letters, notes, memoranda, reports, records, data, computers, disks or other storage media,
sketches, drawings, notebooks, layouts, charts, quotations and proposals, specification sheets, or other written, photographic or other tangible material containing Proprietary Information, and other materials of any nature pertaining to the
Proprietary Information of the Company or its Affiliates, as applicable, and to my work, and will not take or keep in my possession any of the foregoing or any copies. 

7. Enforcement of Intellectual Property Rights. I will cooperate fully with the Company and its successors and assigns, both during and after my
Service to the Company, with respect to the procurement, maintenance and enforcement of Intellectual Property Rights in Company-Related Developments. I will sign, both during and after the term of this Agreement, all papers, including, without
limitation, copyright applications, patent applications, declarations, oaths, assignments of priority rights, and powers of attorney, and provide the Company and its successors and assigns all reasonable assistance which the Company or its
successors or assigns may deem necessary or desirable in order to protect its rights and interests in any Company-Related Development. The Company will reimburse me, in accordance with the Company’s routine expense reimbursement policies, for
out-of-pocket expenses reasonably incurred by me in connection with such activities and, if requested to perform such actions after termination of my Services to the Company, will compensate me at a rate commensurate with my then-current rate of
compensation. If the Company or its successors or assigns is unable, after reasonable effort, to secure my signature on any such papers, I hereby irrevocably designate and appoint each officer of the Company as my agent and attorney-in-fact to
execute any such papers on my behalf, and to take any and all actions as the Company or its successors or assigns may deem necessary or desirable in order to protect its rights and interests in any Company-Related Development. 

8. Non-Competition and Non-Solicitation. 
 In
order to protect the Company’s Proprietary Information and good will, during the term of my Service to the Company or its Affiliates and for the period of time described below following the termination of my Service to the Company or its
Affiliates (the “Restricted Period”), I will not directly or indirectly, whether as owner, partner, shareholder, director, manager, consultant, agent, employee, co-venturer or otherwise, engage, participate or invest in any business
activity with or through any other company anywhere in the United States, the European Union, Switzerland or Japan that conducts or initiates any program to develop, manufacture or market products that are intended to modulate the same target or
operate via the same pathway as any program conducted or 

 

  
 2 

 
actively planned to be conducted by the Company or its Affiliates, including but not limited to a program to develop, manufacture or market a compound that is an MvfR inhibitor, during my Service
to the Company; provided that this shall not prohibit any possible investment in publicly traded stock of a company representing less than one percent of the stock of such company. The “Restricted Period” shall equal the length of my
Service period with the Company or 18 months, whichever is shorter. In addition, during the Restricted Period, I will not, directly or indirectly, in any manner, other than for the benefit of the Company, (a) call upon, solicit, divert, take
away, accept or conduct any business from or with any of the customers or prospective customers of the Company or its Affiliates or any of their suppliers to the extent in competition with, or to the detriment of, the Company, and/or
(b) solicit, entice, attempt to persuade any other employee or consultant of the Company or its Affiliates to leave the Company (or such Affiliate) for any reason or otherwise participate in or facilitate the hire, directly or through another
entity, of any person who is employed or engaged by the Company or its Affiliates or who was employed or engaged by the Company or its Affiliates within six months of any attempt to hire such person. Notwithstanding the foregoing provisions of this
paragraph 8, (i) the Restricted Period shall terminate if my Service to the Company is terminated by the Company without “cause” or if I terminate my Service to the Company as a result of a material uncured diminution of or any other
material and adverse change to my Service to the Company, or if I am required by the Company to relocate my principal place of business by more than 30 miles (acknowledging that requiring frequent travel to the Company’s principal place of
business in the Boston metropolitan area does not constitute “relocation” for purposes of the foregoing) (a “Good Reason Termination”) and (ii) the foregoing does not restrict me from hiring any person who contacts me for
that purpose on an unsolicited basis. I agree that with respect to this provision, any conflicting definition of a for cause termination or Good Reason termination in an agreement between the Company or an Affiliate and me, which is in effect at the
time of such termination, shall supersede the definition contained in this provision. 
 9. Government Contracts. I acknowledge that
the Company and its Affiliates may have from time to time agreements with other persons or with the United States Government or its agencies which impose obligations or restrictions on the Company or its Affiliates regarding inventions made during
the course of work under such agreements or regarding the confidential nature of such work. I agree to comply with any such obligations or restrictions upon the direction of the Company. In addition to the rights assigned under Section 5, I
also assign to the Company or its Affiliate, (or any of its nominees) all rights which I have or acquired in any Developments, full title to which is required to be in the United States under any contract between the Company or its Affiliate and the
United States or any of its agencies. 
 10. Prior Agreements. I hereby represent that [, except with respect to
            ,] I am not bound by the terms of any agreement with any previous employer or other party to 

 
refrain from using or disclosing any trade secret or confidential or proprietary information in the course of my Service to the Company or to refrain from competing, directly or indirectly, with
the business of such previous employer or any other party. I further represent that my performance of all the terms of this Agreement does not, to my knowledge, breach any agreement to keep in confidence proprietary information, knowledge or data
acquired by me in confidence or in trust prior to my Service to the Company. I will not disclose to the Company or its Affiliates or induce the Company or its Affiliates to use any confidential or proprietary information or material belonging to any
previous employer or others. 
 11. Remedies Upon Breach. I understand that the restrictions contained in this Agreement are necessary
for the protection of the business and goodwill of the Company and I consider them to be reasonable for such purpose. Any breach of this Agreement is likely to cause the Company substantial and irrevocable damage and therefore, in the event of such
breach, the Company, in addition to such other remedies which may be available, will be entitled to specific performance and other injunctive relief. 

12. Use of Voice, Image and Likeness. During the period of my Service of the Company, I give the Company and its Affiliates permission to use my
voice, image or likeness, with or without using my name, for the purposes of advertising and promoting the Company or its Affiliates, or for other purposes deemed appropriate by the Company in its reasonable discretion, except to the extent
expressly prohibited by law. 
 13. Publications and Public Statements. I will obtain the Company’s written approval before publishing or
submitting for publication any material that relates to my work at the Company or any of its Affiliates and/or incorporates any Proprietary Information. To ensure that the Company and its Affiliates deliver a consistent message about their
respective products, services and operations to the public, and further in recognition that even positive statements may have a detrimental effect on the Company or its Affiliates in certain securities transactions and other contexts, any statement
about the Company or its Affiliates which I create, publish or post during the term of Service for the Company and for six (6) months thereafter, on any media accessible by the public, including but not limited to social media and networking
services and sites, electronic bulletin boards and Internet-based chat rooms, must first be reviewed and approved by an officer of the Company before it is released in the public domain. After termination of my Services to the Company, neither the
Company nor I will make any disparaging or critical remarks about the other, whether orally, in writing, by social or other electronic media or otherwise, except as may be required by law or an order of a court or governmental entity having
appropriate jurisdiction. 
 14. No Service Obligation. I understand that this Agreement does not create an obligation on the Company or any
other person to continue my Service to the Company. I acknowledge that, unless otherwise agreed in a written agreement signed on behalf of the Company by an authorized 

 

  
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officer, my Service to the Company is at will and therefore may be terminated by the Company or me at any time and for any reason without any obligation or liability to the other except as
expressly set forth in this Agreement. 
 15. Survival and Assignment by the Company. I understand that my obligations under this
Agreement will continue in accordance with its express terms regardless of any changes in my title, position, duties, salary, compensation or benefits or other terms and conditions of my Service for the Company and regardless of the manner of such
termination. The Company will have the right to assign this Agreement to its affiliates, successors and assigns. I expressly consent to be bound by the provisions of this Agreement for the benefit of the Company or any parent, subsidiary or
affiliate to whose Service I may be transferred without the necessity that this Agreement be re-signed at the time of such transfer. 
 16.
Severability. In case any provisions (or portions thereof) contained in this Agreement shall, for any reason, be held invalid, illegal or unenforceable in any respect, such invalidity, illegality or unenforceability shall not
affect the other provisions of this Agreement, and this Agreement shall be construed as if such invalid, illegal or unenforceable 

 
provision had never been contained herein. If, moreover, any one or more of the provisions contained in this Agreement shall for any reason be held to be excessively broad as to duration,
geographical scope, activity or subject, it shall be construed by limiting and reducing it, so as to be enforceable to the extent compatible with the applicable law as it shall then appear. 

17. Interpretation. This Agreement will be deemed to be made and entered into in the Commonwealth of Massachusetts, and will in all
respects be interpreted, enforced and governed under the laws of the Commonwealth of Massachusetts. I hereby agree to consent to personal jurisdiction of the state and federal courts situated within Suffolk County, Massachusetts for purposes of
enforcing this Agreement, and waive any objection that I might have to personal jurisdiction or venue in those courts. 

 

  
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 I UNDERSTAND THAT THIS AGREEMENT AFFECTS IMPORTANT RIGHTS. BY SIGNING BELOW, I CERTIFY THAT I
HAVE READ IT CAREFULLY AND AM SATISFIED THAT I UNDERSTAND IT COMPLETELY. 
 IN WITNESS WHEREOF, the undersigned has executed this
agreement as a sealed instrument as of the date set forth below. 
  

					
	Signed:                                     
                                         
                                         
       	  	 	Date:                                 	 
	
                   
     (full name)
	  			
		
	Type or print name:
                                         
                                         
                       	  			

 EXHIBIT A 
  

			
	To:	  	SPERO THERAPEUTICS, INC.
		
	From:	  	                                     
   
		
	Date:	  	                                     
   
		
	SUBJECT:	  	        Prior Inventions

 The following is a complete list of all inventions or improvements relevant to the subject matter of my
Service of the Company that have been made or conceived or first reduced to practice by me alone or jointly with others prior to my engagement by the Company: 

 

					
	☐    	  	No inventions or improvements	  	
			
	☐    	  	See below:	  	
			
		  	  
	  	
		  	  
	  	
		  	  
	  	
			
	☐	  	Additional sheets attached	  	

 The following is a list of all patents and patent
applications in which I have been named as an inventor: 
  

					
	☐    	  	None	  	
			
	☐    	  	See below:

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