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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* SVLSF VI, LLC (Last) (First) (Middle) 28 STATE STREET, SUITE 980 (Street) BOSTON MA 02109 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 10/08/2026	3. Issuer Name and Ticker or Trading Symbol TRex Bio, Inc. [ TRXB ]
		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)
Common Stock	4,282	I	By SV Life Sciences Fund VI Strategic Partners, L.P.(1)
Common Stock	125,086	I	By SV Life Sciences Fund VI, L.P.(2)

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 Preferred Stock	(3)	(3)	Common Stock	1,574,074	(3)	I	By SV Life Sciences Fund VI, L.P.(2)
Series B Preferred Stock	(3)	(3)	Common Stock	475,411	(3)	I	By SV Life Sciences Fund VI, L.P.(2)
Series A Preferred Stock	(3)	(3)	Common Stock	53,892	(3)	I	By SV Life Sciences Fund VI Strategic Partners, L.P.(1)
Series B Preferred Stock	(3)	(3)	Common Stock	16,277	(3)	I	By SV Life Sciences Fund VI Strategic Partners, L.P.(1)
Series B Preferred Stock	(3)	(3)	Common Stock	669,939	(3)	I	By SV Trex Coinvestment, L.P.(4)

1. Name and Address of Reporting Person* SVLSF VI, LLC (Last) (First) (Middle) 28 STATE STREET, SUITE 980 (Street) BOSTON MA 02109 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* SV Life Sciences Fund VI (GP), L.P. (Last) (First) (Middle) 28 STATE STREET, SUITE 980 (Street) BOSTON MA 02109 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* SV Life Sciences Fund VI, L.P. (Last) (First) (Middle) 28 STATE STREET, SUITE 980 (Street) BOSTON MA 02109 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. The shares are held directly by SV Life Sciences Fund VI Strategic Partners, L.P. ("SV Strategic Partners VI"). SV Life Sciences Fund VI (GP), L.P. (the "GP LP") is the general partner of SV Strategic Partners VI, and SVLSF VI, LLC ("SVLSF") is the general partner of GP LP. Investment and voting decisions of SV Strategic Partners VI are made by the investment committee of SVLSF. Each of GP LP and SVLSF disclaims beneficial ownership except to the extent of its pecuniary interest, and this report is not an admission of beneficial ownership for any other purpose.

2. The shares are held directly by SV Life Sciences Fund VI, L.P. ("SV Fund VI"). GP LP is the general partner of SV Fund VI, and SVLSF is the general partner of GP LP. Investment and voting decisions of SV Fund VI are made by the investment committee of SVLSF. Each of GP LP and SVLSF disclaims beneficial ownership except to the extent of its pecuniary interest, and this report is not an admission of beneficial ownership for any other purpose.

3. 3.8649 shares of preferred stock will automatically convert into 1 share of common stock upon the closing of the issuer's initial public offering, for no additional consideration. The preferred stock has no expiration date.

4. The shares are held directly by SV Trex Coinvestment, L.P. ("SV Coinvestment"). GP LP is the general partner of SV Coinvestment, and SVLSF is the general partner of GP LP. Investment and voting decisions of SV Coinvestment are made by the investment committee of SVLSF. Each of GP LP and SVLSF disclaims beneficial ownership and this report is not an admission of beneficial ownership for any other purpose.

	SVLSF VI, LLC By: Brent M. Faduski, Officer /s/ Brent M. Faduski	10/08/2026
	SV Life Sciences Fund VI (GP), L.P. By: SVLSF VI, LLC, its General Partner By: Brent M. Faduski, Officer /s/ Brent M. Faduski	10/08/2026
	SV Life Sciences Fund VI, L.P. By: SV Life Sciences Fund VI (GP), L.P., its General Partner By: SVLSF VI, LLC, its General Partner By: Brent M. Faduski, Officer /s/ Brent M. Faduski	10/08/2026
	** 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).
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