Sec Form 4 Filing - NeoMed Innovation V L.P. @ Arsanis, Inc. - 2017-11-20

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 NeoMed Innovation V L.P. 2. Issuer Name and Ticker or Trading Symbol Arsanis, Inc. [ ASNS] 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) 13 CASTLE STREET 3. Date of Earliest Transaction (MM/DD/YY) 11/20/2017 (Street) ST HELIER, Y9JE4 5UT 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 11/20/2017 C 246,682 A 246,682 D ( 4 ) Common Stock 11/20/2017 C 41,878 A 288,560 D ( 4 ) Common Stock 11/20/2017 C 279,079 A 567,639 D ( 4 ) Common Stock 11/20/2017 P 300,000 A $ 10 867,639 D ( 4 )

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 Series B Convertible Preferred Stock ( 1 ) 11/20/2017 C 552,487 ( 1 ) ( 1 ) Common Stock 246,682 $ 0 0 D ( 4 ) Series C Convertible Preferred Stock ( 2 ) 11/20/2017 C 84,040 ( 2 ) ( 2 ) Common Stock 41,878 $ 0 0 D ( 4 ) Series D Convertible Preferred Stock ( 3 ) 11/20/2017 C 952,497 ( 3 ) ( 3 ) Common Stock 279,079 $ 0 0 D ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other NeoMed Innovation V L.P. 13 CASTLE STREET ST HELIER, Y9JE4 5UT X NeoMed Management (Jersey) Ltd 13 CASTLE STREET ST HELIER, Y9 X NeoMed Innovation V Ltd 13 CASTLE STREET ST HELIER, Y9 X Signatures /s/ Mike Gray, as attorney-in-fact on behalf of NeoMed Innovation V L.P. 11/20/2017 Signature of Reporting Person Date /s/ Mike Gray, as attorney-in-fact on behalf of NeoMed Management (Jersey) Limited 11/20/2017 Signature of Reporting Person Date /s/ Mike Gray, as attorney-in-fact on behalf of NeoMed Innovation V Limited 11/20/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date. ( 2 )The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date. ( 3 )The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date. ( 4 )The reported securities are held of record by NeoMed Innovation V L.P. NeoMed Management (Jersey) Limited is the Investment Manager to NeoMed Innovation V L.P. NeoMed Innovation V Limited is the general partner of Neomed Innovation V L.P. By virtue of such relationships, NeoMed Management (Jersey) Limited and NeoMed Innovation V Limited may be deemed to have voting and investment power with respect to the shares held by NeoMed Innovation V L.P. Each of NeoMed Management (Jersey) Limited and NeoMed Innovation V Limited disclaims beneficial ownership of the shares held by NeoMed Innovation V L.P., except to the extent of its or his pecuniary interest therein, if any.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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