Sec Form 4 Filing - RA CAPITAL MANAGEMENT, L.P. @ Satsuma Pharmaceuticals, Inc. - 2023-06-08

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 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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1. Name and Address of Reporting Person RA CAPITAL MANAGEMENT, L.P. 2. Issuer Name and Ticker or Trading Symbol Satsuma Pharmaceuticals, Inc. [ STSA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner _____ Officer (give title below) X __ Other (specify below) Former 10% Owner (Last) (First) (Middle) 200 BERKELEY STREET 18TH FLOOR, 3. Date of Earliest Transaction (MM/DD/YY) 06/08/2023 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 06/08/2023 U 5,914,252 D 0 I See Footnotes ( 1 ) ( 2 ) ( 3 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Stock Option (Right to Buy) $ 26.99 06/08/2023 D 10,000 ( 4 ) ( 4 ) Common Stock 10,000 $ 0 ( 5 ) 0 I See Footnotes ( 2 ) ( 6 ) Stock Option (Right to Buy) $ 4.6 06/08/2023 D 20,000 ( 4 ) ( 4 ) Common Stock 20,000 $ 0 ( 5 ) 0 I See Footnotes ( 2 ) ( 6 ) Stock Option (Right to Buy) $ 3.46 06/08/2023 D 30,000 ( 4 ) ( 4 ) Common Stock 30,000 $ 0 ( 5 ) 0 I See Footnotes ( 2 ) ( 6 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 Former 10% Owner RA Capital Healthcare Fund LP C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 Former 10% Owner Kolchinsky Peter C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 Former 10% Owner Signatures /s/ Peter Kolchinsky, Manager of RA Capital Management, L.P. 06/12/2023 Signature of Reporting Person Date /s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC, the General Partner of RA Capital Healthcare Fund, L.P. 06/12/2023 Signature of Reporting Person Date /s/ Peter Kolchinsky, individually 06/12/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Disposed of to SNBL23 Merger Sub, Inc. ("Merger Sub"), which, pursuant to the Agreement and Plan of Merger, dated April 16, 2023, by and between the Issuer, Shin Nippon Biomedical Laboratories, Ltd., a Japanese corporation ("Parent"), and Merger Sub (the "Merger Agreement"), commenced a tender offer to acquire any and all of the outstanding shares of the Issuer's common stock at a purchase price of $0.91 per share and one non-transferable contractual contingent value right (the "Offer Price"). ( 2 )RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein. ( 3 )Held directly by the Fund. ( 4 )Pursuant to the Merger Agreement, each vested option to purchase shares of common stock, par value $0.0001 per share (the "Shares") of the Issuer with an exercise price that is less than $0.91 that is outstanding immediately prior to the date and time at which the Merger became effective (the "Effective Time") will terminate and be cancelled immediately prior to the Effective Time and converted into the right to receive (a) one non-transferable contractual contingent value right and (b) a lump sum cash payment equal in amount to (i) the number of vested Shares underlying such vested option as of immediately prior to the Effective Time, multiplied by (ii) the excess, if any, of $0.91 over the exercise price per Share underlying such vested option, less any required withholding taxes. ( 5 )Pursuant to the Merger Agreement, each option that was not a vested option to purchase Shares of the Issuer with an exercise price that is less than $0.91 and was outstanding immediately prior to the Effective Time was terminated and canceled immediately prior to the Effective Time for no consideration. ( 6 )Under Mr. Shah's arrangement with the Adviser, Mr. Shah holds the options for the benefit of the Fund. Mr. Shah is obligated to turn over to the Adviser any net cash or stock received upon sale of the common stock underlying the option and restricted stock units, which will offset advisory fees owed by the Fund to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and respective underlying common stock except to the extent of their pecuniary interest.

Remarks: Mr. Shah, a Managing Partner of the Adviser, serves on the Issuer's board of directors.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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