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* Frazier Life Sciences X, L.P. (Last) (First) (Middle) 601 UNION STREET, SUITE 3200 (Street) SEATTLE WA 98101 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 09/12/2024	3. Issuer Name and Ticker or Trading Symbol MBX Biosciences, Inc. [ MBX ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 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 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
Series A Convertible Preferred Stock	(1)	(1)	Common Stock	1,574,005	(1)	D(2)
Series B Convertible Preferred Stock	(1)	(1)	Common Stock	2,353,769	(1)	D(2)

1. Name and Address of Reporting Person* Frazier Life Sciences X, L.P. (Last) (First) (Middle) 601 UNION STREET, SUITE 3200 (Street) SEATTLE WA 98101 (City) (State) (Zip)

1. Name and Address of Reporting Person* FHMLS X, L.P. (Last) (First) (Middle) 601 UNION STREET, SUITE 3200 (Street) SEATTLE WA 98101 (City) (State) (Zip)

1. Name and Address of Reporting Person* FHMLS X, L.L.C. (Last) (First) (Middle) 601 UNION STREET, SUITE 3200 (Street) SEATTLE WA 98101 (City) (State) (Zip)

1. Name and Address of Reporting Person* Topper James N (Last) (First) (Middle) 601 UNION STREET, SUITE 3200 (Street) SEATTLE WA 98101 (City) (State) (Zip)

Explanation of Responses:

1. Each share of Series A Convertible Preferred Stock, Series B Convertible Preferred Stock and Series C Convertible Preferred Stock (collectively, the "Preferred Stock") is convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and will automatically convert into the number of shares shown in Column 3 immediately prior to the closing of the Issuer's initial public offering. The Preferred Stock has no expiration date.

2. These securities are held of record by Frazier Life Sciences X, L.P. ("FLS X"). FHMLS X, L.P. is the general partner of FLS X, and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick Heron and James Topper, M.D., Ph.D., are the sole managing members of FHMLS X, L.L.C. and share voting and investment power of the securities held by FLS X, and as a result, may be deemed to have beneficial ownership over such securities. Mr. Heron and Dr. Topper disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein.

Remarks:

Exhibit 24 - Power of Attorney

	Frazier Life Sciences X, L.P., By: FHMLS X, L.P., its general partner, By: FHMLS X, L.L.C., its general partner, By: /s/ Steve R. Bailey, Chief Financial Officer	09/12/2024
	FHMLS X, L.P., By: FHMLS X, L.L.C., its general partner, By: /s/ Steve R. Bailey, Chief Financial Officer	09/12/2024
	FHMLS X, L.L.C., By: /s/ Steve R. Bailey, Chief Financial Officer	09/12/2024
	/s/ Steve R. Bailey, Attorney-in-Fact for James N. Topper	09/12/2024
	** Signature of Reporting Person	Date
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EXHIBIT 24

 

POWER OF ATTORNEY

 

KNOW ALL BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Steve R. Bailey with full power to act singly, his true and lawful attorney-in-fact, with full power of substitution, to: (i) sign any and all instruments, certificates and documents that may be necessary, desirable or appropriate to be executed on behalf of himself as an individual or in his capacity as a general partner of any partnership or limited liability company, pursuant to Section 13 or 16 of the Securities Exchange Act of 1934, as amended, and any and all regulations promulgated thereunder, (ii) file the same (including any amendments thereto), with all exhibits thereto, and any other documents in connection therewith, with the Securities and Exchange Commission, and any stock exchange or similar authority and (iii) take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this power of attorney shall be in such form and shall contain such terms and conditions as such attorney‑in‑fact may approve in such attorney‑in‑fact's discretion, granting unto said attorney-in-fact full power and authority to do and perform each and every act and thing necessary, desirable or appropriate.

 

Each of the undersigned hereby grant to the attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted.

 

This power of attorney shall remain in full force and effect until revoked by the undersigned in a signed writing delivered to the attorney-in-fact.

 

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 16th day of February, 2016.

 

 

	/s/ James Topper
James Topper

 

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