<SEC-DOCUMENT>0000899243-17-025133.txt : 20171101
<SEC-HEADER>0000899243-17-025133.hdr.sgml : 20171101
<ACCEPTANCE-DATETIME>20171101192451
ACCESSION NUMBER:		0000899243-17-025133
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20171101
FILED AS OF DATE:		20171101
DATE AS OF CHANGE:		20171101

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Deshpande Milind
		CENTRAL INDEX KEY:			0001378588

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38266
		FILM NUMBER:		171170313

	MAIL ADDRESS:	
		STREET 1:		ACHILLION PHARMACEUTICALS
		STREET 2:		300 GEORGE STREET
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06511

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Spero Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001701108
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		675 MASSACHUSETTS AVENUE
		STREET 2:		14TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		857-242-1600

	MAIL ADDRESS:	
		STREET 1:		675 MASSACHUSETTS AVENUE
		STREET 2:		14TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Spero Therapeutics, LLC
		DATE OF NAME CHANGE:	20170316
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc3.xml
<DESCRIPTION>FORM 3 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2017-11-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001701108</issuerCik>
        <issuerName>Spero Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>SPRO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001378588</rptOwnerCik>
            <rptOwnerName>Deshpande Milind</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SPERO THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>675 MASSACHUSETTS AVENUE, 14TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02139</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16454</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.90</value>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-07-05</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3290</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.90</value>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-07-05</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>45191</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The number of shares reported reflects a 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.</footnote>
        <footnote id="F2">The shares underlying this option vested as to 25% on August 24, 2016, with the remainder vesting in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service through the applicable vesting date.</footnote>
        <footnote id="F3">The number of underlying shares of common stock and the exercise price reported reflect a 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.</footnote>
        <footnote id="F4">The shares underlying this option vest as to 25% on July 6, 2018, with the remainder vesting in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service through the applicable vesting date.</footnote>
    </footnotes>

    <remarks>Exhibit 24.1 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Matthew Tikonoff, Attorney-in-Fact for Milind Deshpande</signatureName>
        <signatureDate>2017-11-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24.1
<SEQUENCE>2
<FILENAME>attachment1.htm
<DESCRIPTION>EX-24.1 DOCUMENT
<TEXT>
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<HEAD>
</HEAD>
<BODY>
<PRE>
                                  POWER OF ATTORNEY

     Know all by these present, that the undersigned hereby constitutes and
appoints each of Ankit Mahadevia, M.D., Chief Executive Officer and President
of Spero Therapeutics, Inc.(the "Company"), Joel Sendek, Chief Financial Officer
and Treasurer of the Company, Stephen Garbacz, Vice President of Finance and
Operations and Secretary of the Company, and Matthew J. Gardella, Matthew
W. Tikonoff, Leah J. Pollema, Brain J. Shea, Anne T. Leland, Brenda L. Meyette
and Jacquelyn Cannata of Mintz, Levin, Chon, Ferris, Glovsky and Popeo, P.C.,
singing singly, with full power of substitution, the undersigned's true and
lawful attorney-in-fact to:

     (1)    execute for and on behalf of the undersigned, forms and
            authentication documents for EDGAR Filing Access;

     (2)    do and perform any and all acts for and on behalf of the undersigned
            which may be necessary or desirable to complete and execute any such
            forms and authentication documents;

     (3)    execute for and on behalf of the undersigned, in the undersigned's
            capacity as an officer, director and/or 10% shareholder of the
            Company, Forms 3, 4 and 5 in accordance with Section 16(a) of the
            Securities Exchange Act of 1934 and the rules thereunder;

     (4)    do and perform any and all acts for and on behalf of the undersigned
            which may be necessary or desirable to complete and execute any such
            Form 3, 4 or 5 and timely file such form with the United States
            Securities and Exchange Commission and any stock exchange or similar
            authority; and

     (5)    take any other action of any type whatsoever in connection with the
            foregoing which, in the opinion of such attorney-in-fact, may be of
            benefit to, in the best interests of, or legally required by the
            undersigned, it being understood that the documents executed by such
            attorney-in-fact on behalf of the undersigned pursuant to this Power
            of Attorney shall be in such form and shall contain such terms and
            conditions as such attorney-in-fact may approve in such attorney-
            in-fact's discretion.

     The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934, as amended.

     This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed this 26th day of October, 2017

                                                /s/ Milind Deshpande
                                        -------------------------------------
                                                      Signature

                                                   Milind Deshpande
                                        -------------------------------------
                                                      Print Name








</PRE>
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</DOCUMENT>
</SEC-DOCUMENT>
