<SEC-DOCUMENT>0001562180-21-006828.txt : 20211104
<SEC-HEADER>0001562180-21-006828.hdr.sgml : 20211104
<ACCEPTANCE-DATETIME>20211104160305
ACCESSION NUMBER:		0001562180-21-006828
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20211022
FILED AS OF DATE:		20211104
DATE AS OF CHANGE:		20211104

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Nolte Alexander
		CENTRAL INDEX KEY:			0001891979

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37708
		FILM NUMBER:		211379835

	MAIL ADDRESS:	
		STREET 1:		35 GATEHOUSE DRIVE
		STREET 2:		BUILDING D, FLOOR 3
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Syndax Pharmaceuticals Inc
		CENTRAL INDEX KEY:			0001395937
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				320162505
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		35 GATEHOUSE DRIVE
		STREET 2:		BUILDING D, FLOOR 3
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		781-419-1400

	MAIL ADDRESS:	
		STREET 1:		35 GATEHOUSE DRIVE
		STREET 2:		BUILDING D, FLOOR 3
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2021-10-22</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001395937</issuerCik>
        <issuerName>Syndax Pharmaceuticals Inc</issuerName>
        <issuerTradingSymbol>SNDX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001891979</rptOwnerCik>
            <rptOwnerName>Nolte Alexander</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SYNDAX PHARMACEUTICALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>35 GATEHOUSE DRIVE, BUILDING D, FLOOR 3</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02451</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Chief Accounting Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>21.36</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-02-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>62000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.36</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-09-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>35000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>18.03</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2030-05-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.63</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-02-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.47</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2030-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>16000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.24</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-05-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>11667.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-07-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.38</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-02-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>18000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning February 28, 2021, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F2">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning September 30, 2021, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F3">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning May 31, 2020, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F4">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning February 28, 2018, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F5">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning February 29, 2020, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F6">Twenty-five percent (25%) of the total number of shares underlying the option vested on May 1, 2018, and one forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F7">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning July 31, 2019, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
        <footnote id="F8">One forty-eighth (1/48th) of the total number of shares underlying the option vest monthly thereafter on the last day of each month, beginning February 28, 2019, subject to the reporting person's continuous service on the relevant vesting dates.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Michael A. Metzger, as Attorney-in-Fact</signatureName>
        <signatureDate>2021-11-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>noltepoa.htm
<DESCRIPTION>NOLTE POA
<TEXT>
<center><b>POWER OF ATTORNEY</b></center <br><br>

The undersigned, an officer of Syndax
Pharmaceuticals, Inc., a Delaware corporation (the <u>"Company"</u>), hereby
constitutes and appoints Michael Metzger and Luke Albrecht, for so
long as each such person is an employee of the Company, and Laura Berezin,
for so long as she is a partner of a law firm representing the Company, the
undersigned's true and lawful attorney-in-fact, each with the power to act
alone for the undersigned and in the undersigned's name, place and stead, to:
<br><br>

1. Prepare, complete and execute Forms 3, 4 and 5 under the Securities
Exchange Act of 1934, as amended (the <u>"Exchange Act"</u>), and other forms
and all amendments thereto on the undersigned's behalf as such
attorney-in-fact shall in his or her discretion determine to be required or
advisable pursuant to Section 16 of the Exchange Act and the rules and
regulations promulgated thereunder, or any successor laws and regulations,
as a consequence of the undersigned's beneficial ownership of securities of
the Company or changes in such beneficial ownership; and <br><br>

2. Do all acts necessary in order to file such forms and amendments with the
 Securities and Exchange Commission, any securities exchange or national
association, the Company and such other persons or agencies as the
attorney-in-fact shall deem appropriate. <br><br>

The undersigned hereby ratifies and confirms all that said attorneys-in-fact
and agents shall do or cause to be done by virtue hereof. 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
or liability under Section 16 of the Exchange Act or any rules and
regulations promulgated thereunder or any successor laws and regulations.
<br><br>

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

The undersigned has executed this Power of Attorney as of October 25, 2021.
<br><br>


<u>/s/ Alexander Nolte</u><br>
Alexander Nolte
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
