<SEC-DOCUMENT>0000059478-20-000185.txt : 20201203
<SEC-HEADER>0000059478-20-000185.hdr.sgml : 20201203
<ACCEPTANCE-DATETIME>20201203210045
ACCESSION NUMBER:		0000059478-20-000185
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201203
FILED AS OF DATE:		20201203
DATE AS OF CHANGE:		20201203

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ELI LILLY & Co
		CENTRAL INDEX KEY:			0000059478
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		STATE OF INCORPORATION:			IN
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39746
		FILM NUMBER:		201368410

	BUSINESS ADDRESS:	
		STREET 1:		LILLY CORPORATE CTR
		STREET 2:		DROP CODE 1094
		CITY:			INDIANAPOLIS
		STATE:			IN
		ZIP:			46285
		BUSINESS PHONE:		3172762000

	MAIL ADDRESS:	
		STREET 1:		LILLY CORPORATE CENTER
		STREET 2:		DROP CODE 1094
		CITY:			INDIANAPOLIS
		STATE:			IN
		ZIP:			46285

	FORMER NAME:	
		FORMER CONFORMED NAME:	LILLY ELI & CO
		DATE OF NAME CHANGE:	19941024

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Sigilon Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001821323
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				474005543
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		100 BINNEY STREET
		STREET 2:		STE 600
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		617-336-7540

	MAIL ADDRESS:	
		STREET 1:		100 BINNEY STREET
		STREET 2:		STE 600
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_160704722837838.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2020-12-03</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001821323</issuerCik>
        <issuerName>Sigilon Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>SGTX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000059478</rptOwnerCik>
            <rptOwnerName>ELI LILLY &amp; Co</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>LILLY CORPORATE CENTER</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>INDIANAPOLIS</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46285</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series A-3 Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1555555.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series B Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>888888.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Series A-3 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the &quot;Preferred Stock&quot;) is convertible into the number of shares of the Registrant's common stock shown in column 3 and has no expiration date. The Preferred Stock will automatically convert into common stock upon the closing of the Registrant's initial public offering.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Erin Conway, Assistant Secretary</signatureName>
        <signatureDate>2020-12-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
