Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Flynn James E
  2. Issuer Name and Ticker or Trading Symbol
Aclaris Therapeutics, Inc. [ACRS]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
780 THIRD AVENUE, 37TH FLOOR, 
3. Date of Earliest Transaction (Month/Day/Year)
12/28/2018
(Street)

NEW YORK, NY 10017
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock               4,481,788 I Through Deerfield Partners, L.P. (1) (2)
Common Stock               1,411,628 I Through Deerfield Special Situations Fund, L.P. (1) (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Cash-Settled Total Return Swap (3) $ 6.999 (4) 12/28/2018   J/K   1 (3)     (3) 01/19/2022 Common Stock 14,200 (3) 1 I Through Deerfield Partners, L.P. (1) (2)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Flynn James E
780 THIRD AVENUE, 37TH FLOOR
NEW YORK, NY 10017
    X    
Deerfield Mgmt L.P.
780 THIRD AVENUE
37TH FLOOR
NEW YORK, NY 10017
    X    
DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C)
780 THIRD AVENUE, 37TH FLOOR
NEW YORK, NY 10017
    X    
Deerfield Special Situations Fund, L.P.
780 3RD AVENUE
37TH FLOOR
NEW YORK, NY 10017
      Possible Member of a 10% Group
DEERFIELD PARTNERS, L.P.
780 THIRD AVENUE
37TH FLOOR
NEW YORK, NY 10017
    X    

Signatures

 /s/ Jonathan Isler, Attorney-in-Fact   01/02/2019
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of Deerfield Partners, L.P. ("Deerfield Partners") and Deerfield Special Situations Fund, L.P. (collectively with Deerfield Partners, the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.
(2) In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.
(3) On December 28, 2018, Deerfield Partners entered into a cash-settled total return swap agreement with an unaffiliated third party financial institution, which provides Deerfield Partners with economic exposure to an aggregate of 14,200 notional shares. The swap agreement provides Deerfield Partners with economic results that are comparable to the economic results of ownership of, based on the applicable reference prices, but does not provide Deerfield Partners with the power to vote or direct the voting of, or dispose of or direct the disposition of, the shares of common stock that are the subject of such swap agreement.
(4) The price reported in Column 2 represents a weighted average reference price associated with the swap agreement. The reference prices applicable to the 14,200 notional shares subject to the swap agreement reported herein range from $6.98 to $7.00, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of notional shares subject to each separate reference price within the range set forth in this footnote (4).
 
Remarks:
Jonathan Isler, Attorney-in-Fact: Power of Attorney, which is hereby incorporated by reference to Exhibit 24 to a Form 3 with regard to Proteon Therapeutics, Inc. filed with the Securities and Exchange Commission on August 4, 2017 by Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield Management Company, L.P., and James E. Flynn. See footnote (1)

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