Sec Form 4 Filing - Title 19 Promis @ ProMIS Neurosciences Inc. - 2025-07-25

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 Title 19 Promis 2. Issuer Name and Ticker or Trading Symbol ProMIS Neurosciences Inc. [ PMN] 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) C/O TROVE,, 40 BROAD STREET, 8TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 07/25/2025 (Street) BOSTON, MA02109 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 Shares, no par value 07/25/2025 X( 1 ) 119,800 A 2,195,429 D Common Shares, no par value 07/25/2025 X( 2 ) 119,800 A 2,315,229 D Common Shares, no par value 07/25/2025 X( 3 ) 119,800 A 2,435,029 D

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 Tranche A Common Share Purchase Warrants ( 1 ) 07/25/2025 X 119,800 ( 1 ) ( 1 ) Common Shares 119,800 $ 0 345,316 D Tranche B Common Share Purchase Warrants ( 2 ) 07/25/2025 X 119,800 ( 2 ) ( 2 ) Common Shares 119,800 $ 0 345,316 D Tranche C Common Share Purchase Warrants ( 3 ) 07/25/2025 X 119,800 ( 3 ) ( 3 ) Common Shares 119,800 $ 0 345,316 D Warrants to Purchase Common Shares ( 4 ) 07/29/2025 P 539,100 ( 4 ) ( 4 ) Common Shares 539,100 ( 4 ) 539,100 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Title 19 Promis C/O TROVE, 40 BROAD STREET, 8TH FLOOR BOSTON, MA02109 X Signatures Title 19 Promis By: /s/ Michael S. Gordon, Manager 07/29/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On July 25, 2025, Title 19 Promis exercised 119,800 Tranche A purchase warrants, each exercisable to purchase one Common Share. These warrants were exercisable at an exercise price of $2.02 per warrant share; however, following an offer by Title 19 Promis and an acceptance by the Issuer, were exercised at an exercise price of $0.83158 per share. The remainder of these warrants are currently exercisable and expire on the earlier of (i) 18 months of the issue date and (ii) within 60 days of the public announcement via press release or the filing of a Current Report on Form 8-K of 6-month data from the cohorts treated with single ascending doses of PMN310. ( 2 )On July 25, 2025, Title 19 Promis exercised 119,800 Tranche B purchase warrants, each exercisable to purchase one Common Share. These warrants were exercisable at an exercise price of $2.02 per warrant share; however, following an offer by Title 19 Promis and an acceptance by the Issuer, were exercised at an exercise price of $0.83158 per share. The remainder of these warrants are currently exercisable and expire on the earlier of (i) 30 months of the issue date and (ii) within 60 days of the public announcement via press release or the filing of a Current Report on Form 8-K of 12-month data from the cohorts treated with single ascending doses of PMN310. ( 3 )On July 25, 2025, Title 19 Promis exercised 119,800 Tranche C purchase warrants, each exercisable to purchase one Common Share. These warrants were exercisable at an exercise price of $2.50 per warrant share; however, following an offer by Title 19 Promis and an acceptance by the Issuer, were exercised at an exercise price of $0.83158 per share. The remainder of these warrants are currently exercisable and expire on July 31, 2029. ( 4 )On July 29, 2025, Title 19 Promis acquired 539,100 warrants, each exercisable to purchase one Common Share, at an exercise price of $1.25 per share. The purchase price for each warrant was $0.1875 per share. The warrants are currently exercisable and expire five years after the date of issuance.

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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