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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-05-07</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000318306</issuerCik>
        <issuerName>ABEONA THERAPEUTICS INC.</issuerName>
        <issuerTradingSymbol>ABEO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001535978</rptOwnerCik>
            <rptOwnerName>Adage Capital Management, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CLARENDON STREET, 52ND FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403404</rptOwnerCik>
            <rptOwnerName>Atchinson Robert</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CLARENDON STREET</rptOwnerStreet1>
            <rptOwnerStreet2>52ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403413</rptOwnerCik>
            <rptOwnerName>Gross Phillip</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CLARENDON STREET</rptOwnerStreet1>
            <rptOwnerStreet2>52ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Pre-funded Warrant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2024-05-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2948475</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.0699</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2948475</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2948475</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Initial exercise price is $0.0001, subject to adjustments as set forth in the Pre-funded Warrant.</footnote>
        <footnote id="F2">Subject to the terms and conditions set forth in the Pre-funded Warrant, the holder thereof may, at any time and from time to time on or after May 7, 2024, exercise the Pre-funded Warrant until it has been exercised in full. The Pre-funded Warrants contain an issuance limitation prohibiting the holder of such Pre-funded Warrants from exercising the Pre-funded Warrants until such time as the holder, together with certain related parties, would not beneficially own after any such exercise more than 9.99% of the then issued and outstanding common stock (the &quot;Blocker&quot;). Due to the Blocker, the Pre-funded Warrants held by ACP (as defined below) are not presently exercisable in full.</footnote>
        <footnote id="F3">The securities to which this filing relates are held directly by Adage Capital Partners, L.P., a Delaware limited partnership (&quot;ACP&quot;). Adage Capital Management, L.P., a Delaware limited partnership (&quot;ACM&quot;), serves as the investment manager of ACP and as such has discretion over the portfolio securities held by ACP. Robert Atchinson and Phillip Gross are the managing members of (i) Adage Capital Advisors, L.L.C., a Delaware limited liability company, managing member of Adage Capital Partners GP, L.L.C., a Delaware limited liability company, general partner of ACP and (ii) Adage Capital Partners LLC, a Delaware limited liability company, general partner of ACM.</footnote>
        <footnote id="F4">Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Section 16 of the Securities and Exchange Act of 1934, as amended, except as to such extent of such Reporting Person's pecuniary interest in the securities, if any.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Adage Capital Management, L.P.; By: its general partner Adage Capital Partners LLC; By its managing member Robert Atchinson</signatureName>
        <signatureDate>2024-05-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Robert Atchinson</signatureName>
        <signatureDate>2024-05-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Phillip Gross</signatureName>
        <signatureDate>2024-05-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
