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        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001761918</identifier>
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        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
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    <dei:DocumentType contextRef="P01_01_2025To12_31_2025" id="hidden163886675">DEF 14A</dei:DocumentType>
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    <dei:EntityCentralIndexKey contextRef="P01_01_2025To12_31_2025" id="ixv-4239">0001761918</dei:EntityCentralIndexKey>
    <dei:EntityRegistrantName contextRef="P01_01_2025To12_31_2025" id="ixv-4249">Erasca, Inc.</dei:EntityRegistrantName>
    <ecd:InsiderTrdPoliciesProcAdoptedFlag contextRef="P01_01_2025To12_31_2025" id="ixv-4253">true</ecd:InsiderTrdPoliciesProcAdoptedFlag>
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    <ecd:AwardTmgMethodTextBlock contextRef="P01_01_2025To12_31_2025" id="ixv-2109">We have had no program, plan or practice pertaining to the timing of stock option grants to NEOs coinciding with the release of material &lt;div style="white-space: nowrap; letter-spacing: 0px; top: 0px;display:inline;"&gt;non-public&lt;/div&gt; information. Annual grants of stock options to employees are typically approved by the Compensation Committee or our Chief Executive Officer pursuant to a delegation of authority from the Compensation Committee in the first quarter of each year as part of our annual compensation cycle.</ecd:AwardTmgMethodTextBlock>
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    <ecd:MnpiDiscTimedForCompValFlag contextRef="P01_01_2025To12_31_2025" id="ixv-4257">false</ecd:MnpiDiscTimedForCompValFlag>
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