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                    <ccc>XXXXXXXX</ccc>
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            <liveTestFlag>LIVE</liveTestFlag>



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            <issuerCik>0001560241</issuerCik>
            <issuerName>G1 THERAPEUTICS, INC.</issuerName>
            <secFileNumber>001-38096</secFileNumber>
            <issuerAddress>
                <ns2:street1>700 Park Offices Drive, Suite 200</ns2:street1>
                <ns2:city>Research Triangle Park</ns2:city>
                <ns2:stateOrCountry>NC</ns2:stateOrCountry>
                <ns2:zipCode>27709</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>(919) 213-9835</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>MARK VELLECA</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Director</relationshipToIssuer>
            </relationshipsToIssuer>
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        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>38th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>60000</noOfUnitsSold>
            <aggregateMarketValue>119974.08</aggregateMarketValue>
            <noOfUnitsOutstanding>51745578</noOfUnitsOutstanding>
            <approxSaleDate>08/08/2023</approxSaleDate>
            <securitiesExchangeName>NASD</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>08/08/2023</acquiredDate>
            <natureOfAcquisitionTransaction>Stock Option Exercise</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>60000</amountOfSecuritiesAcquired>
            <paymentDate>08/08/2023</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <noticeSignature>
            <noticeDate>08/08/2023</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>05/05/2023</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ Mark Albert Velleca</signature>
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144
0001706847
XXXXXXXX
LIVE
0001560241
G1 THERAPEUTICS, INC.
001-38096
700 Park Offices Drive, Suite 200
Research Triangle Park
NC
27709
(919) 213-9835
MARK VELLECA
Director
Common
Morgan Stanley Smith Barney LLC
1 New York Plaza
38th Floor
New York
NY
10004
60000
119974.08
51745578
08/08/2023
NASD
Common
08/08/2023
Stock Option Exercise
Issuer
N
60000
08/08/2023
Cash
Y
08/08/2023
05/05/2023
/s/ Mark Albert Velleca