<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2022-02-03</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001786205</issuerCik>
        <issuerName>Arcellx, Inc.</issuerName>
        <issuerTradingSymbol>ACLX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001598542</rptOwnerCik>
            <rptOwnerName>Carroll Jill</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ARCELLX, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>25 WEST WATKINS MILL ROAD, SUITE A</rptOwnerStreet2>
            <rptOwnerCity>GAITHERSBURG</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20878</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series A 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>1550309</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series B-1 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>666651</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series B-2 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>533389</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series C 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>1082991</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">All shares of Series A Preferred Stock, par value $0.001 per share, Series B-1 Preferred Stock, par value $0.001 per share, Series B-2 Preferred Stock, par value $0.001 per share, and Series C Preferred Stock, par value $0.001 per share, of the Issuer will automatically be converted on a one-for-one basis to shares of the Issuer's common stock, par value $0.001 per share (&quot;Common Stock&quot;) prior to the closing of the Issuer's initial public offering of its Common Stock, and have no expiration date.</footnote>
        <footnote id="F2">Shares directly held by SR One Capital Fund I Aggregator, L.P. SR One Capital Partners I, LP serves as the general partner of SR One Capital Fund I Aggregator, LP and SR One Capital Management, LLC serves as the general partner of SR One Capital Partners I, LP. The Reporting Person, a member of the Issuer's board of directors, is a partner of SR One Capital Management, LP, an entity affiliated with SR One Capital Fund I Aggregator, L.P. and, therefore, may be deemed to have a pecuniary interest over these shares. The Reporting Person disclaims beneficial ownership of the shares held of record by SR One Capital Fund I Aggregator, L.P. except to the extent of her pecuniary interest therein.</footnote>
        <footnote id="F3">Consists of 649,795 shares held by SR One Capital Fund I Aggregator, L.P. and 433,196 shares held by SR One Co-Invest II, LLC. SR One Capital Partners I, LP serves as the general partner of SR One Capital Fund I Aggregator, LP and SR One Capital Management, LLC serves as the general partner of SR One Capital Partners I, LP. SR One Co-Invest Manager II, LLC serves as the manager of SR Co-Invest II, LLC, and SR One Capital Management, LLC serves as the managing member of SR Co-Invest Manager II, LLC. The Reporting Person, a member of the Issuer's board of directors, is a partner of SR One Capital Management, LP, an entity affiliated with SR One Capital Fund I Aggregator, L.P. and SR One Co-Invest II, LLC and, therefore, may be deemed to have a pecuniary interest over these shares. The Reporting person disclaims beneficial ownership of the shares held of record by SR One Capital Fund I Aggregator, L.P. and SR One Co-Invest II, LLC except to the extent of her pecuniary in</footnote>
    </footnotes>

    <remarks>Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Lance Thibault, as Attorney-in-Fact</signatureName>
        <signatureDate>2022-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
