<SEC-DOCUMENT>0001172661-25-002072.txt : 20250515
<SEC-HEADER>0001172661-25-002072.hdr.sgml : 20250515
<ACCEPTANCE-DATETIME>20250515104524
ACCESSION NUMBER:		0001172661-25-002072
CONFORMED SUBMISSION TYPE:	SCHEDULE 13G/A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20250515
DATE AS OF CHANGE:		20250515

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Aclaris Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001557746
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				460571712
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SCHEDULE 13G/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-89137
		FILM NUMBER:		25949880

	BUSINESS ADDRESS:	
		STREET 1:		701 LEE ROAD
		STREET 2:		SUITE 103
		CITY:			WAYNE
		STATE:			PA
		ZIP:			19087
		BUSINESS PHONE:		484-324-7933

	MAIL ADDRESS:	
		STREET 1:		701 LEE ROAD
		STREET 2:		SUITE 103
		CITY:			WAYNE
		STATE:			PA
		ZIP:			19087

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Rock Springs Capital Management LP
		CENTRAL INDEX KEY:			0001595725
		ORGANIZATION NAME:           	
		EIN:				800944416
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SCHEDULE 13G/A

	BUSINESS ADDRESS:	
		STREET 1:		650 SOUTH EXETER STREET
		STREET 2:		SUITE 1070
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202
		BUSINESS PHONE:		4102200129

	MAIL ADDRESS:	
		STREET 1:		650 SOUTH EXETER STREET
		STREET 2:		SUITE 1070
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202
</SEC-HEADER>
<DOCUMENT>
<TYPE>SCHEDULE 13G/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/schedule13g" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>SCHEDULE 13G/A</submissionType>
    <previousAccessionNumber>0001172661-24-005356</previousAccessionNumber>
    <filerInfo>
      <filer>
        <filerCredentials>
          <!-- Field: Pseudo-Tag; ID: Name; Data: Rock Springs Capital Management LP -->
          <cik>0001595725</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <coverPageHeader>
      <amendmentNo>1</amendmentNo>
      <securitiesClassTitle>Common Stock, $0.00001 par value</securitiesClassTitle>
      <eventDateRequiresFilingThisStatement>03/31/2025</eventDateRequiresFilingThisStatement>
      <issuerInfo>
        <issuerCik>0001557746</issuerCik>
        <issuerName>Aclaris Therapeutics, Inc.</issuerName>
        <issuerCusip>00461U105</issuerCusip>
        <issuerPrincipalExecutiveOfficeAddress>
          <com:street1>701 LEE ROAD, SUITE 103</com:street1>
          <com:city>WAYNE</com:city>
          <com:stateOrCountry>PA</com:stateOrCountry>
          <com:zipCode>19087</com:zipCode>
        </issuerPrincipalExecutiveOfficeAddress>
      </issuerInfo>
      <designateRulesPursuantThisScheduleFiled>
        <designateRulePursuantThisScheduleFiled>Rule 13d-1(c)</designateRulePursuantThisScheduleFiled>
      </designateRulesPursuantThisScheduleFiled>
    </coverPageHeader>
    <coverPageHeaderReportingPersonDetails>


      <reportingPersonName>Rock Springs Capital Management LP</reportingPersonName>
      <citizenshipOrOrganization>DE</citizenshipOrOrganization>
      <reportingPersonBeneficiallyOwnedNumberOfShares>
        <soleVotingPower>0.00</soleVotingPower>
        <sharedVotingPower>5046309.00</sharedVotingPower>
        <soleDispositivePower>0.00</soleDispositivePower>
        <sharedDispositivePower>5046309.00</sharedDispositivePower>
      </reportingPersonBeneficiallyOwnedNumberOfShares>
      <reportingPersonBeneficiallyOwnedAggregateNumberOfShares>5046309.00</reportingPersonBeneficiallyOwnedAggregateNumberOfShares>
      <aggregateAmountExcludesCertainSharesFlag>N</aggregateAmountExcludesCertainSharesFlag>
      <classPercent>4.7</classPercent>
      <typeOfReportingPerson>IA</typeOfReportingPerson>
    </coverPageHeaderReportingPersonDetails>
    <coverPageHeaderReportingPersonDetails>


      <reportingPersonName>Rock Springs Capital LLC</reportingPersonName>
      <citizenshipOrOrganization>DE</citizenshipOrOrganization>
      <reportingPersonBeneficiallyOwnedNumberOfShares>
        <soleVotingPower>0.00</soleVotingPower>
        <sharedVotingPower>5046309.00</sharedVotingPower>
        <soleDispositivePower>0.00</soleDispositivePower>
        <sharedDispositivePower>5046309.00</sharedDispositivePower>
      </reportingPersonBeneficiallyOwnedNumberOfShares>
      <reportingPersonBeneficiallyOwnedAggregateNumberOfShares>5046309.00</reportingPersonBeneficiallyOwnedAggregateNumberOfShares>
      <aggregateAmountExcludesCertainSharesFlag>N</aggregateAmountExcludesCertainSharesFlag>
      <classPercent>4.7</classPercent>
      <typeOfReportingPerson>HC</typeOfReportingPerson>
      <typeOfReportingPerson>OO</typeOfReportingPerson>
    </coverPageHeaderReportingPersonDetails>
    <coverPageHeaderReportingPersonDetails>

      <reportingPersonName>Rock Springs Capital Master Fund LP</reportingPersonName>
      <citizenshipOrOrganization>E9</citizenshipOrOrganization>
      <reportingPersonBeneficiallyOwnedNumberOfShares>
        <soleVotingPower>0.00</soleVotingPower>
        <sharedVotingPower>0.00</sharedVotingPower>
        <soleDispositivePower>0.00</soleDispositivePower>
        <sharedDispositivePower>0.00</sharedDispositivePower>
      </reportingPersonBeneficiallyOwnedNumberOfShares>
      <reportingPersonBeneficiallyOwnedAggregateNumberOfShares>0.00</reportingPersonBeneficiallyOwnedAggregateNumberOfShares>
      <aggregateAmountExcludesCertainSharesFlag>N</aggregateAmountExcludesCertainSharesFlag>
      <classPercent>0</classPercent>
      <typeOfReportingPerson>PN</typeOfReportingPerson>
    </coverPageHeaderReportingPersonDetails>
    <coverPageHeaderReportingPersonDetails>

      <reportingPersonName>Mark Bussard</reportingPersonName>
      <citizenshipOrOrganization>X1</citizenshipOrOrganization>
      <reportingPersonBeneficiallyOwnedNumberOfShares>
        <soleVotingPower>0.00</soleVotingPower>
        <sharedVotingPower>5046309.00</sharedVotingPower>
        <soleDispositivePower>0.00</soleDispositivePower>
        <sharedDispositivePower>5046309.00</sharedDispositivePower>
      </reportingPersonBeneficiallyOwnedNumberOfShares>
      <reportingPersonBeneficiallyOwnedAggregateNumberOfShares>5046309.00</reportingPersonBeneficiallyOwnedAggregateNumberOfShares>
      <aggregateAmountExcludesCertainSharesFlag>N</aggregateAmountExcludesCertainSharesFlag>
      <classPercent>4.7</classPercent>
      <typeOfReportingPerson>HC</typeOfReportingPerson>
      <typeOfReportingPerson>IN</typeOfReportingPerson>
    </coverPageHeaderReportingPersonDetails>
    <coverPageHeaderReportingPersonDetails>

      <reportingPersonName>Kris Jenner</reportingPersonName>
      <citizenshipOrOrganization>X1</citizenshipOrOrganization>
      <reportingPersonBeneficiallyOwnedNumberOfShares>
        <soleVotingPower>0.00</soleVotingPower>
        <sharedVotingPower>5046309.00</sharedVotingPower>
        <soleDispositivePower>0.00</soleDispositivePower>
        <sharedDispositivePower>5046309.00</sharedDispositivePower>
      </reportingPersonBeneficiallyOwnedNumberOfShares>
      <reportingPersonBeneficiallyOwnedAggregateNumberOfShares>5046309.00</reportingPersonBeneficiallyOwnedAggregateNumberOfShares>
      <aggregateAmountExcludesCertainSharesFlag>N</aggregateAmountExcludesCertainSharesFlag>
      <classPercent>4.7</classPercent>
      <typeOfReportingPerson>HC</typeOfReportingPerson>
      <typeOfReportingPerson>IN</typeOfReportingPerson>
    </coverPageHeaderReportingPersonDetails>
    <items>
      <item1>
        <issuerName>Aclaris Therapeutics, Inc.</issuerName>
        <issuerPrincipalExecutiveOfficeAddress>701 LEE ROAD, SUITE 103, WAYNE, PA, 19087</issuerPrincipalExecutiveOfficeAddress>
      </item1>
      <item2>
        <filingPersonName>This Statement is filed on behalf of each of the following persons (collectively, the "Reporting Persons"):

i. Rock Springs Capital Management LP ("RSCM");
ii. Rock Springs Capital LLC ("RSC");
iii. Rock Springs Capital Master Fund LP ("Master Fund");
iv. Mark Bussard; and
v. Kris Jenner

This Statement relates to the shares of Common Stock (the "Shares") held directly by the Master Fund, which is a Cayman Island exempted limited partnership, and Four Pines Master Fund LP ("Four Pines"), which is a Cayman Islands exempted limited partnership, and indirectly held by RSCM, a Delaware limited partnership, and RSC, a Delaware limited liability company. RSCM serves as the investment manager to each of the Master Fund and Four Pines. RSC is the general partner of RSCM. Mark Bussard and Kris Jenner each own 50% of the management company.</filingPersonName>
        <principalBusinessOfficeOrResidenceAddress>Rock Springs Capital Management LP, Rock Springs Capital LLC, Rock Springs Capital Master Fund LP; Mark Bussard, and Kris Jenner:

650 South Exeter, Suite 1070
Baltimore, MD 21202</principalBusinessOfficeOrResidenceAddress>
        <citizenship>Rock Springs Capital Management LP - Delaware; Rock Springs Capital LLC - Delaware; Rock Springs Capital Master Fund LP - Cayman Islands; Mark Bussard - United States; Kris Jenner - United States</citizenship>
      </item2>
      <item3>
        <notApplicableFlag>Y</notApplicableFlag>
      </item3>
      <item4>
        <amountBeneficiallyOwned>5,046,309</amountBeneficiallyOwned>
        <classPercent>4.7</classPercent>
        <numberOfSharesPersonHas>
          <solePowerOrDirectToVote>0</solePowerOrDirectToVote>
          <sharedPowerOrDirectToVote>5,046,309</sharedPowerOrDirectToVote>
          <solePowerOrDirectToDispose>0</solePowerOrDirectToDispose>
          <sharedPowerOrDirectToDispose>5,046,309

The percent of class is determined by dividing the number of Shares beneficially owned by the Reporting Persons by 107,918,821, as reported on the Issuer's 10-K filed on February 27, 2025.</sharedPowerOrDirectToDispose>
        </numberOfSharesPersonHas>
      </item4>
      <item5>
        <notApplicableFlag>N</notApplicableFlag>
        <classOwnership5PercentOrLess>Y</classOwnership5PercentOrLess>
      </item5>
      <item6>
        <notApplicableFlag>N</notApplicableFlag>
        <ownershipMoreThan5PercentOnBehalfOfAnotherPerson>See disclosure in Items 2 and 4 hereof. Certain funds listed in Item 2(a) are known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares covered by this Statement that may be deemed to be beneficially owned by the Reporting Persons.</ownershipMoreThan5PercentOnBehalfOfAnotherPerson>
      </item6>
      <item7>
        <notApplicableFlag>N</notApplicableFlag>
        <subsidiaryIdentificationAndClassification>Please see response to Item 2.</subsidiaryIdentificationAndClassification>
      </item7>
      <item8>
        <notApplicableFlag>Y</notApplicableFlag>
      </item8>
      <item9>
        <notApplicableFlag>Y</notApplicableFlag>
      </item9>
      <item10>
        <notApplicableFlag>N</notApplicableFlag>
        <certifications>By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.</certifications>
      </item10>
    </items>
    <exhibitInfo>JOINT FILING AGREEMENT

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G/A is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G/A shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

Date: May 15, 2025

Rock Springs Capital Management LP

By: Rock Springs Capital LLC, General Partner

By:  Mark Bussard
Name: Mark Bussard
Title: Member

Rock Springs Capital LLC

By: Mark Bussard
Name: Mark Bussard
Title: Member

Rock Springs Capital Master Fund LP

By: Rock Springs Capital Management LP, Investment Manager
By: Rock Springs Capital LLC, General Partner

By: Mark Bussard
Name: Mark Bussard
Title: Member

Mark Bussard

By:  Mark Bussard
Name: Mark Bussard

Kris Jenner

By: Kris Jenner
Name: Kris Jenner</exhibitInfo>
    <signatureInformation>
      <reportingPersonName>Rock Springs Capital Management LP</reportingPersonName>
      <signatureDetails>
        <signature>/s/ Mark Bussard</signature>
        <title>Mark Bussard - Member</title>
        <date>05/15/2025</date>
      </signatureDetails>
    </signatureInformation>
    <signatureInformation>
      <reportingPersonName>Rock Springs Capital LLC</reportingPersonName>
      <signatureDetails>
        <signature>/s/ Mark Bussard</signature>
        <title>Mark Bussard - Member</title>
        <date>05/15/2025</date>
      </signatureDetails>
    </signatureInformation>
    <signatureInformation>
      <reportingPersonName>Rock Springs Capital Master Fund LP</reportingPersonName>
      <signatureDetails>
        <signature>/s/ Mark Bussard</signature>
        <title>Mark Bussard - Member</title>
        <date>05/15/2025</date>
      </signatureDetails>
    </signatureInformation>
    <signatureInformation>
      <reportingPersonName>Mark Bussard</reportingPersonName>
      <signatureDetails>
        <signature>/s/ Mark Bussard</signature>
        <title>Mark Bussard</title>
        <date>05/15/2025</date>
      </signatureDetails>
    </signatureInformation>
    <signatureInformation>
      <reportingPersonName>Kris Jenner</reportingPersonName>
      <signatureDetails>
        <signature>/s/ Kris Jenner</signature>
        <title>Kris Jenner</title>
        <date>05/15/2025</date>
      </signatureDetails>
    </signatureInformation>
  </formData>
</edgarSubmission>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
