<SEC-DOCUMENT>0001104659-25-043510.txt : 20250501
<SEC-HEADER>0001104659-25-043510.hdr.sgml : 20250501
<ACCEPTANCE-DATETIME>20250501160154
ACCESSION NUMBER:		0001104659-25-043510
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250429
FILED AS OF DATE:		20250501
DATE AS OF CHANGE:		20250501

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SHALLCROSS STEVEN A
		CENTRAL INDEX KEY:			0001263501
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12584
		FILM NUMBER:		25902865

	BUSINESS ADDRESS:	
		STREET 1:		C/O ELYS GAME TECHNOLOGY CORP.
		STREET 2:		130 ADELAIDE STREET WEST, SUITE 701
		CITY:			TORONTO
		STATE:			A6
		ZIP:			M5H2K4
		BUSINESS PHONE:		301 944 6600

	MAIL ADDRESS:	
		STREET 1:		C/O ELYS GAME TECHNOLOGY CORP.
		STREET 2:		130 ADELAIDE STREET WEST, SUITE 701
		CITY:			TORONTO
		STATE:			A6
		ZIP:			M5H2K4

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Theriva Biologics, Inc.
		CENTRAL INDEX KEY:			0000894158
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				133808303
		STATE OF INCORPORATION:			NV
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		9605 MEDICAL CENTER DRIVE
		STREET 2:		SUITE 270
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850
		BUSINESS PHONE:		(734) 332-7800

	MAIL ADDRESS:	
		STREET 1:		9605 MEDICAL CENTER DRIVE
		STREET 2:		SUITE 270
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Synthetic Biologics, Inc.
		DATE OF NAME CHANGE:	20120305

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ADEONA PHARMACEUTICALS, INC.
		DATE OF NAME CHANGE:	20081027

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PIPEX PHARMACEUTICALS, INC.
		DATE OF NAME CHANGE:	20061214
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>tm2513725-3_4seq1.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-04-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000894158</issuerCik>
        <issuerName>Theriva Biologics, Inc.</issuerName>
        <issuerTradingSymbol>TOVX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001263501</rptOwnerCik>
            <rptOwnerName>SHALLCROSS STEVEN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THERIVA BIOLOGICS, INC.,</rptOwnerStreet1>
            <rptOwnerStreet2>9605, MEDICAL CENTER DRIVE, SUITE 270</rptOwnerStreet2>
            <rptOwnerCity>ROCKVILLE</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20850</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.4144</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-04-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>190000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-05-01</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2032-04-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>190000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>190000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These stock options vest pro rata on a monthly basis over 36 months.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Steven A. Shallcross</signatureName>
        <signatureDate>2025-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
