RA Capital Healthcare Fund LP Form 3 Filed 2024-03-27

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, 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. Date of Event Requiring Statement (Month/Day/Year)

03/27/2024

3. Issuer Name and Ticker or Trading Symbol

Boundless Bio, Inc. [BOLD]

(Last)

(First)

(Middle)

200 BERKELEY STREET,

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 Original Filed (Month/Day/Year)

(Street)

BOSTON, MA 02116

(City)

(State)

(Zip)

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 of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Series B Preferred Stock	⁽¹⁾	⁽¹⁾	Common Stock	871,794	⁽¹⁾	I	See footnotes⁽²⁾⁽³⁾
Series B Preferred Stock	⁽¹⁾	⁽¹⁾	Common Stock	153,846	⁽¹⁾	I	See footnotes⁽³⁾⁽⁴⁾
Series C Preferred Stock	⁽¹⁾	⁽¹⁾	Common Stock	716,118	⁽¹⁾	I	See footnotes⁽²⁾⁽³⁾
Series C Preferred Stock	⁽¹⁾	⁽¹⁾	Common Stock	126,373	⁽¹⁾	I	See footnotes⁽³⁾⁽⁴⁾

Reporting Owners

Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET BOSTON, MA 02116		X
RA Capital Healthcare Fund LP 200 BERKELEY STREET BOSTON, MA 02116		X
RA Capital Nexus Fund II, L.P. 200 BERKELEY STREET BOSTON, MA 02116		X
Kolchinsky Peter C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET BOSTON, MA 02116		X
Shah Rajeev M. RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116		X

Explanation of Responses:

1.	Each share of Series B Preferred Stock and Series C Preferred Stock will automatically convert into shares of Common Stock on a 19.5-for-1 basis immediately prior to the closing of the Issuer's initial public offering and have no expiration date.
2.	Held directly by RA Capital Healthcare Fund, L.P. (the "Fund").
3.	RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund and RA Capital Nexus Fund II, L.P. (the "Nexus Fund II"). 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.
4.	Held directly by Nexus Fund II.

	Signatures
	/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.	03/27/2024
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.	03/27/2024
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC the General Partner of RA Capital Nexus Fund II, L.P.	03/27/2024
	/s/ Peter Kolchinsky, individually	03/27/2024
	/s/ Rajeev Shah, individually	03/27/2024
	** Signature of Reporting Person	Date
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