Form SC 13G - Statement of Beneficial Ownership by Certain Investors

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

Schedule 13G

Under the Securities Exchange Act of 1934

(Amendment No. )*

Aclaris Therapeutics, Inc.

(Name of Issuer)

Common Stock, $0.00001 par value

(Title of Class of Securities)

00461U105

(CUSIP Number)

November 18, 2024

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

o Rule 13d-1(b)

x Rule 13d-1(c)

o Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 00461U105

Schedule 13G

Page 2 of 9 Pages


1	NAME OF REPORTING PERSONS Rock Springs Capital Management LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 6,761,861
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 6,761,861
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,761,861
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.32%
12	TYPE OF REPORTING PERSON IA

CUSIP No. 00461U105

Schedule 13G

Page 3 of 9 Pages


1	NAME OF REPORTING PERSONS Rock Springs Capital LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 6,761,861
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 6,761,861
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,761,861
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.32%
12	TYPE OF REPORTING PERSON OO; HC

CUSIP No. 00461U105

Schedule 13G

Page 4 of 9 Pages


1	NAME OF REPORTING PERSONS Rock Springs Capital Master Fund LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) o
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 5,697,000
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 5,697,000
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,697,000
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.32%
12	TYPE OF REPORTING PERSON PN

CUSIP No. 00461U105

Schedule 13G

Page 5 of 9 Pages

Item 1.

(a) Name of Issuer

Aclaris Therapeutics, Inc. (the “Issuer”)

(b) Address of Issuer’s Principal Executive Offices

701 Lee Road, Suite 103

Wayne, PA 19087

Item 2.

(a) Name of Person Filing

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”); and

iii. Rock Springs Capital Master Fund LP (“Master Fund”).

This Statement relates to Shares (as defined herein) 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.

(b) Address of Principal Business Office, or, if none, Residence

Rock Springs Capital Management LP and Rock Springs Capital LLC

650 South Exeter, Suite 1070

Baltimore, MD 21202

Rock Springs Capital Master Fund

c/o Walkers Corporate Limited

190 Elgin Avenue

George Town, Grand Cayman, KY1-9008, Cayman Islands

(c) Citizenship

Rock Springs Capital Management LP - Delaware

Rock Springs Capital LLC - Delaware

Rock Springs Capital Master Fund LP - Cayman Islands

(d) Title of Class of Securities

Common Stock, $0.00001 par value (the “Shares”)

(e) CUSIP No.:

00461U105

CUSIP No. 00461U105

Schedule 13G

Page 6 of 9 Pages


Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)	¨	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)	¨	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)	¨	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)	¨	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)	o	An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)	¨	An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)	o	A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)	¨	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)	¨	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)	¨	A non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J);

(k)	¨	A group, in accordance with §240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J), please specify the type of institution:

CUSIP No. 00461U105

Schedule 13G

Page 7 of 9 Pages

Item 4. Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

As of November 18, 2024, each of RSCM and RSC may be deemed to be the beneficial owners of 6,761,861 Shares, which amount includes 5,697,000 Shares directly beneficially owned by the Master Fund, and 1,064,861 Shares directly beneficially owned by Four Pines. The percent of class is determined by dividing the number of Shares beneficially owned by the Reporting Persons by 106,986,497 as reported on the Issuer’s Form 8-K filed on November 18, 2024.

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