SEC FORM 3

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^*

GILLIS STEVEN

(Last)

(First)

(Middle)

ARCH VENTURE PARTNERS,

1000 2ND AVE., SUITE 3700

(Street)

SEATTLE

98104

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/17/2006

3. Issuer Name and Ticker or Trading Symbol
Trubion Pharmaceuticals, Inc [ TRBN ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)	X	Other (specify below)
			Ind. gen. partner of 10% owner

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	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)
Common Stock	23,920	I	See footnotes⁽¹⁾⁽⁴⁾

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)
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	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
Stock Option (right to buy)	⁽⁵⁾	03/08/2016	Common Stock	19,135	$6.5218	D
Series A Preferred Stock	10/17/2006	⁽⁷⁾	Common Stock	1,047,724	⁽⁶⁾	I	See footnotes⁽²⁾⁽⁴⁾
Series B Preferred Stock	10/17/2006	⁽⁷⁾	Common Stock	1,240,762	⁽⁶⁾	I	See footnotes⁽³⁾⁽⁴⁾

Explanation of Responses:

1. Represents (a) 23,762 shares of common stock held by ARCH Venture Fund V, L.P. (b) 158 shares of common stock held by ARCH V Entrepreneurs Fund, L.P.

2. Represents (a) 979,880 shares of common stock held by ARCH Venture Fund V, L.P.; (b) 6,511 shares of common stock held by ARCH V Entrepreneurs Fund, L.P.; and (c) 61,333 shares of common stock held by Healthcare Focus Fund, L.P.

3. Represents (a) 1,161,459 shares of common stock held by ARCH Venture Fund V, L.P.; (b) 7,834 shares of common stock held by ARCH V Entrepreneurs Fund, L.P.; and (c) 71,469 shares of common stock held by Healthcare Focus Fund, L.P.

4. Reporting person is a director of Trubion Pharmaceuticals, Inc. and holds the title of limited partner of ARCH Ventures Fund V, L.P. Dr. Gillis disclaims beneficial ownership of shares owned by these entities.

5. 30,000 shares vest on 1/25/06 and 1/48 monthly thereafter of remaining balance

6. 1-for-1

7. No expiration date

	/s/ Lauree Seko	10/17/2006
	** 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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