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    <periodOfReport>2019-02-15</periodOfReport>

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    <issuer>
        <issuerCik>0001581720</issuerCik>
        <issuerName>Loxo Oncology, Inc.</issuerName>
        <issuerTradingSymbol>LOXO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001250195</rptOwnerCik>
            <rptOwnerName>ELMS STEVE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>888 SEVENTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>30TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10106</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
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            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
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            <transactionAmounts>
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                    <value>2038920</value>
                </transactionShares>
                <transactionPricePerShare>
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                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <ownershipNature>
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                    <value>I</value>
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                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
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            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
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            <expirationDate>
                <value>2026-06-09</value>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                <value>Employee Stock Option (Right to Buy)</value>
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                <value>2019-02-15</value>
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                <transactionShares>
                    <value>11000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>235.00</value>
                    <footnoteId id="F3"/>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <exerciseDate>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2027-06-21</value>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                <underlyingSecurityShares>
                    <value>11000</value>
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                    <value>D</value>
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        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
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                <value>180.98</value>
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                <value>2019-02-15</value>
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                <transactionPricePerShare>
                    <value>235.00</value>
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                    <value>D</value>
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                <footnoteId id="F3"/>
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                <value>2028-06-12</value>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                    <value>8750</value>
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                    <value>0</value>
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    <footnotes>
        <footnote id="F1">Pursuant to the Agreement and Plan of Merger (the &quot;Merger Agreement&quot;) dated January 5, 2019, between Eli Lilly and Company, an Indiana corporation (&quot;Lilly&quot;), Bowfin Acquisition Corporation, Inc., a Delaware corporation and a wholly owned subsidiary of Lilly (&quot;Merger Sub&quot;), and Loxo Oncology, Inc., a Delaware corporation (&quot;Loxo Oncology&quot;), Merger Sub will merge with and into Loxo Oncology, with Loxo Oncology surviving as a wholly owned subsidiary of Lilly (the &quot;Merger&quot;). Pursuant to the Merger Agreement each issued and outstanding shares (the &quot;Shares&quot;) of Loxo common stock, par value $0.0001 per share, was purchased at a price of $235.00 per share (the &quot;Offer Price&quot;), net to the seller in cash, without interest, and subject to withholding taxes.</footnote>
        <footnote id="F2">The securities are directly held by Aisling Capital III, LP (&quot;Aisling&quot;), and indirectly held by Aisling Capital Partners III, LP (&quot;Aisling GP&quot;), as general partner of Aisling, Aisling Capital Partners III LLC (&quot;Aisling Partners&quot;), as general partner of Aisling GP, and each of the individual managing members and partners (collectively, the &quot;Managers&quot;) of Aisling GP and Aisling Partners. The Managers of Aisling Partners are Dennis Purcell, Dr. Andrew Schiff and Steve Elms. Mr. Elms is a member of the Issuer's Board of Directors. Dr. Joshua Bilenker, the Issuer's President and Chief Executive Officer, is a member of the Issuer's Board of Directors and an Operating Partner of Aisling GP. Mr. Elms is a member of the investment committee (the &quot;Investment Committee&quot;) of Aisling GP. The Investment Committee has voting and dispositive power over the shares held by Aisling.</footnote>
        <footnote id="F3">Pursuant to the Merger Agreement, as of immediately prior to the Effective Time, each Loxo Oncology stock option that is then-outstanding and unvested shall become immediately vested and exercisable in full. At the Effective Time, each Loxo Oncology stock option that is outstanding under the Loxo Oncology Equity Incentive Plans (including any unvested Loxo stock options for which the vesting was accelerated immediately prior to the Effective Time as described above) will be cancelled and converted into the right to receive an amount in cash equal to the product of (x) the number of Shares issuable under such option multiplied by (y) the excess, if any, of (A) the Offer Price over (B) the per share exercise price of such option. Any outstanding option with an exercise price equal to or greater than the Offer Price will be cancelled for no consideration at the Effective Time.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Jennifer Burstein, by power of attorney</signatureName>
        <signatureDate>2019-02-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
