<SEC-DOCUMENT>0001209191-20-063298.txt : 20201214
<SEC-HEADER>0001209191-20-063298.hdr.sgml : 20201214
<ACCEPTANCE-DATETIME>20201214175843
ACCESSION NUMBER:		0001209191-20-063298
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201210
FILED AS OF DATE:		20201214
DATE AS OF CHANGE:		20201214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			5AM Ventures V, L.P.
		CENTRAL INDEX KEY:			0001674324
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387457

	BUSINESS ADDRESS:	
		STREET 1:		2200 SAND HILL ROAD, SUITE 110
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025
		BUSINESS PHONE:		(650) 233-8600

	MAIL ADDRESS:	
		STREET 1:		2200 SAND HILL ROAD, SUITE 110
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			5AM Opportunities I (GP), LLC
		CENTRAL INDEX KEY:			0001790778
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387458

	BUSINESS ADDRESS:	
		STREET 1:		501 2ND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107
		BUSINESS PHONE:		(650) 233-86000

	MAIL ADDRESS:	
		STREET 1:		501 2ND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			5AM Opportunities I, L.P.
		CENTRAL INDEX KEY:			0001753000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387459

	BUSINESS ADDRESS:	
		STREET 1:		501 SECOND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107
		BUSINESS PHONE:		415-993-8570

	MAIL ADDRESS:	
		STREET 1:		501 SECOND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			5AM Partners V, LLC
		CENTRAL INDEX KEY:			0001791889
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387460

	BUSINESS ADDRESS:	
		STREET 1:		501 SECOND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107
		BUSINESS PHONE:		650-233-8600

	MAIL ADDRESS:	
		STREET 1:		501 SECOND STREET, SUITE 350
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PARMAR KUSH
		CENTRAL INDEX KEY:			0001664281

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387461

	MAIL ADDRESS:	
		STREET 1:		C/O AUDENTES THERAPEUTICS, INC.
		STREET 2:		101 MONTGOMERY ST., SUITE 2650
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROCKLAGE SCOTT M
		CENTRAL INDEX KEY:			0001219014

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387462

	MAIL ADDRESS:	
		STREET 1:		179 SANDY POND ROAD
		CITY:			LINCOLN
		STATE:			MA
		ZIP:			01773

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Schwab Andrew J.
		CENTRAL INDEX KEY:			0001598549

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39103
		FILM NUMBER:		201387463

	MAIL ADDRESS:	
		STREET 1:		C/O 5AM VENTURES, 2200 SAND HILL ROAD
		STREET 2:		SUITE 110
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Cabaletta Bio, Inc.
		CENTRAL INDEX KEY:			0001759138
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2929 ARCH STREET
		STREET 2:		SUITE 600
		CITY:			PHILADELPHIA
		STATE:			PA
		ZIP:			19104
		BUSINESS PHONE:		(267) 759-3100

	MAIL ADDRESS:	
		STREET 1:		2929 ARCH STREET
		STREET 2:		SUITE 600
		CITY:			PHILADELPHIA
		STATE:			PA
		ZIP:			19104
</SEC-HEADER>
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    <issuer>
        <issuerCik>0001759138</issuerCik>
        <issuerName>Cabaletta Bio, Inc.</issuerName>
        <issuerTradingSymbol>CABA</issuerTradingSymbol>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001674324</rptOwnerCik>
            <rptOwnerName>5AM Ventures V, L.P.</rptOwnerName>
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            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
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    <reportingOwner>
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            <rptOwnerCik>0001790778</rptOwnerCik>
            <rptOwnerName>5AM Opportunities I (GP), LLC</rptOwnerName>
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        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001753000</rptOwnerCik>
            <rptOwnerName>5AM Opportunities I, L.P.</rptOwnerName>
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        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001791889</rptOwnerCik>
            <rptOwnerName>5AM Partners V, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
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    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001664281</rptOwnerCik>
            <rptOwnerName>PARMAR KUSH</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001219014</rptOwnerCik>
            <rptOwnerName>ROCKLAGE SCOTT M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
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            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
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    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001598549</rptOwnerCik>
            <rptOwnerName>Schwab Andrew J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>501 2ND STREET, SUITE 350</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-12-10</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>261084</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2953634</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-12-10</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>36916</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>417629</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares are held directly by 5AM Ventures V, L.P. (&quot;5AM V&quot;).</footnote>
        <footnote id="F2">5AM Partners V, LLC (&quot;5AM Partners&quot;) is the sole general partner of 5AM V.  Dr. Kush Parmar, Andrew J. Schwab and Dr. Scott M. Rocklage are managing members of 5AM Partners and may be deemed to have shared voting and investment power over the shares beneficially owned by 5AM V.  Each of 5AM Partners, Dr. Parmar, Mr. Schwab and Dr. Rocklage disclaims beneficial ownership of the shares of Preferred Stock held directly by 5AM V, except to the extent of its or his pecuniary interest therein.</footnote>
        <footnote id="F3">Shares are held directly by 5AM Opportunities I, L.P. (&quot;Opportunities&quot;).</footnote>
        <footnote id="F4">5AM Opportunities I (GP), LLC (&quot;Opportunities GP&quot;) is the sole general partner of Opportunities.  Andrew J. Schwab and Dr. Kush Parmar are managing members of Opportunities GP and may be deemed to have shared voting and investment power over the shares beneficially owned by Opportunities.  Each of Opportunities GP, Mr. Schwab and Dr. Parmar disclaims beneficial ownership of the shares of Common Stock held directly by Opportunities, except to the extent of its or his pecuniary interest therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By: 5AM Partners V, LLC,
its General Partner
By: /s/ Scott M. Rocklage
Managing Member</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ Kush Parmar Managing Member</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: 5AM Opportunities I (GP), LLC, its General Partner By: /s/ Kush Parmar Managing Member</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ Scott M. Rocklage Managing Member</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Kush Parmar</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Rocklage</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Andrew J. Schwab</signatureName>
        <signatureDate>2020-12-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</DOCUMENT>
</SEC-DOCUMENT>
