SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* RTW INVESTMENTS, LP (Last) (First) (Middle) 412 WEST 15TH STREET, FLOOR 9 (Street) NEW YORK NY 10011 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 05/08/2019	3. Issuer Name and Ticker or Trading Symbol Milestone Pharmaceuticals Inc. [ MIST ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of 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

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Class D-1 Preferred	(1)	(1)	Common Shares	2,651,247(2)	(1)	I	By RTW(3)
Class D-2 Preferred	(1)	(1)	Common Shares	203,942(4)	(1)	I	By RTW(3)

1. Name and Address of Reporting Person* RTW INVESTMENTS, LP (Last) (First) (Middle) 412 WEST 15TH STREET, FLOOR 9 (Street) NEW YORK NY 10011 (City) (State) (Zip)

1. Name and Address of Reporting Person* WONG RODERICK (Last) (First) (Middle) C/O RTW INVESTMENTS, LP 412 WEST 15TH STREET, FLOOR 9 (Street) NEW YORK NY 10011 (City) (State) (Zip)

Explanation of Responses:

1. Each share of Class D-1 Preferred and Class D-2 Preferred is convertible at any time, at the option of the holder, into Common Shares, on a one-for-one basis, has no expiration date and will convert into Common Shares upon the closing of the Issuer's initial public offering.

2. Consists of 2,301,909 shares held directly by RTW Master Fund, Ltd. and 349,338 shares held by RTW Innovation Master Fund, Ltd.

3. The securities reported herein may be deemed beneficially owned by each of: (i) RTW Investments, LP ("RTW"), which is deemed the beneficial owner of shares held by RTW Master Fund, Ltd. and RTW Innovation Master Fund, Ltd. (the "Funds"), which are investment funds managed by RTW, and (ii) Roderick Wong, M.D who serves as the Managing Partner and Chief Investment Officer of RTW. Dr. Wong exercises voting and dispositive control over the securities held by RTW and is therefore deemed to be a beneficial owner of securities owned or controlled by RTW. Each of RTW and Dr. Wong disclaim beneficial ownership of the reported securities held by the Funds, except to the extent of its or his pecuniary interest therein.

4. Consists of 177,070 shares held directly by RTW Master Fund, Ltd. and 26,872 shares held by RTW Innovation Master Fund, Ltd.

	RTW Investments, LP /s/ Roderick Wong, Managing Partner	05/08/2019
	Roderick Wong /s/ Roderick Wong	05/08/2019
	** Signature of Reporting Person	Date
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 5 (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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