SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13G

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2 (b)

(Amendment No. 3)*

Altus Pharmaceuticals Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

02216N105

(CUSIP Number)

December 31, 2009

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

o

Rule 13d-1(b)

o

Rule 13d-1(c)

x

Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(Continued on following pages)

Page 1 of 20 Pages

Exhibit Index Contained on Page 19

CUSIP NO. 02216N105

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Page 2 of 20

1	NAME OF REPORTING SS OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON U.S. Venture Partners VIII, L.P. (“USVP VIII”)
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 180,816 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that Presidio Management Group VIII, L.L.C. (“PMG VIII”), the general partner of USVP VIII, may be deemed to have sole power to vote such shares, and Timothy Connors (“Connors”), Irwin Federman (“Federman”), Winston Fu (“Fu”), Steven M. Krausz (“Krausz”), David Liddle (“Liddle”), Jonathan D. Root (“Root”), Christopher Rust (“Rust”) and Philip M. Young (“Young”), the managing members of PMG VIII, may be deemed to have shared power to vote such shares.
		6	SHARED VOTING POWER See response to row 5.
		7	SOLE DISPOSITIVE POWER 180,816 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP VIII, may be deemed to have the sole power to dispose of such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to dispose of such shares.
		8	SHARED DISPOSITIVE POWER See response to row 7.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 180,816
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* PN

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Page 3 of 20

1	NAME OF REPORTING SS OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON USVP VIII Affiliates Fund, L.P. (“USVP VIII AF”)
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 1,332 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP VIII AF, may be deemed to have sole power to vote such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to vote such shares.
		6	SHARED VOTING POWER See response to row 5.
		7	SOLE DISPOSITIVE POWER 1,332 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP VIII AF, may be deemed to have sole power to dispose of such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to dispose of such shares.
		8	SHARED DISPOSITIVE POWER See response to row 7.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,332
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON* PN

CUSIP NO. 02216N105

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Page 4 of 20

1	NAME OF REPORTING SS OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON USVP Entrepreneur Partners VIII-A, L.P. (“USVP EP VIII-A”)
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 1,694 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP EP VIII-A, may be deemed to have sole power to vote such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to vote such shares.
		6	SHARED VOTING POWER See response to row 5.
		7	SOLE DISPOSITIVE POWER 1,694 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP EP VIII-A, may be deemed to have sole power to dispose of such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to dispose of such shares.
		8	SHARED DISPOSITIVE POWER See response to row 7.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,694
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON* PN

CUSIP NO. 02216N105

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Page 5 of 20

1	NAME OF REPORTING SS OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON USVP Entrepreneur Partners VIII-B, L.P. (“USVP EP VIII-B”)
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 909 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP EP VIII-B, may be deemed to have sole power to vote such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to vote such shares.
		6	SHARED VOTING POWER See response to row 5.
		7	SOLE DISPOSITIVE POWER 909 shares issuable upon the conversion of warrants that are exercisable within 60 days; except that PMG VIII, the general partner of USVP EP VIII-B, may be deemed to have sole power to dispose of such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to dispose of such shares.
		8	SHARED DISPOSITIVE POWER See response to row 7.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 909
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON* PN

CUSIP NO. 02216N105

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Page 6 of 20

1	NAME OF REPORTING SS OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Presidio Management Group VIII, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII, the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B, may be deemed to have sole power to vote such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to vote such shares.
		6	SHARED VOTING POWER See response to row 5.
		7	SOLE DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII, the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B, may be deemed to have sole power to dispose of such shares, and Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young, the managing members of PMG VIII, may be deemed to have shared power to dispose of such shares.
		8	SHARED DISPOSITIVE POWER See response to row 7.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* OO

CUSIP NO. 02216N105

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Page 7 of 20

1	NAME OF REPORTING PERSON       Timothy Connors
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Connors, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Connors, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

CUSIP NO. 02216N105

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Page 8 of 20

1	NAME OF REPORTING PERSON       Irwin Federman
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Federman, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Federman, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

CUSIP NO. 02216N105

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Page 9 of 20

1	NAME OF REPORTING PERSON        Winston Fu
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Fu, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Fu, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

CUSIP NO. 02216N105

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Page 10 of 20

1	NAME OF REPORTING PERSON       Steven M. Krausz
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Krausz, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Krausz, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

CUSIP NO. 02216N105

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Page 11 of 20

1	NAME OF REPORTING PERSON       David Liddle
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Liddle, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Liddle, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

CUSIP NO. 02216N105

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Page 12 of 20

1	NAME OF REPORTING PERSON       Jonathan D. Root
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Root, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Root, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

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Page 13 of 20

1	NAME OF REPORTING PERSON       Christopher Rust
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Rust, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Rust, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

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1	NAME OF REPORTING PERSON       Philip M. Young
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION U.S. Citizen
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0 shares
		6	SHARED VOTING POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Young, a managing member of PMG VIII, may be deemed to have shared power to vote such shares.
		7	SOLE DISPOSITIVE POWER 0 shares
		8	SHARED DISPOSITIVE POWER 184,751 shares issuable upon the conversion of warrants that are exercisable within 60 days, of which 180,816 are directly owned by USVP VIII, 1,332 are directly owned by USVP VIII AF, 1,694 are directly owned by USVP EP VIII-A and 909 are directly owned by USVP EP VIII-B.  PMG VIII is the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Young, a managing member of PMG VIII, may be deemed to have shared power to dispose of such shares.
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 184,751
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.6%
12	TYPE OF REPORTING PERSON* IN

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This Amendment No. 3 amends and restates in its entirety the Schedule 13G previously filed by Presidio Management Group VIII, L.L.C., U.S. Venture Partners VIII, L.P., USVP VIII Affiliates Fund, L.P., USVP Entrepreneur Partners VIII-A, L.P., USVP Entrepreneur Partners VIII-B, L.P., Timothy Connors, Irwin Federman, Winston Fu, Steven M. Krausz, David Liddle, Jonathan D. Root, Christopher Rust and Philip M. Young (together with all prior and current amendments thereto, this “Schedule 13G”).  

ITEM 1(A).

NAME OF ISSUER

Altus Pharmaceuticals Inc.

ITEM 1(B).

ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES

610 Lincoln Street

Waltham, MA 02451

ITEM 2(A).

NAME OF PERSONS FILING

This Schedule 13G is filed by Presidio Management Group VIII, L.L.C., a Delaware limited liability company (“PMG VIII”), U.S. Venture Partners VIII, L.P., a Delaware limited partnership (“USVP VIII”), USVP VIII Affiliates Fund, L.P., a Delaware limited partnership (“USVP VIII AF”), USVP Entrepreneur Partners VIII-A, L.P., a Delaware limited partnership (“USVP EP VIII-A”), U.S. Entrepreneur Partners VIII-B, a Delaware limited partnership (“USVP EP VIII-B”), Timothy Connors (“Connors”), Irwin Federman (“Federman”), Winston Fu (“Fu”), Steven M. Krausz (“Krausz”), David Liddle (“Liddle”), Jonathan D. Root (“Root”) Christopher Rust (“Rust”) and Philip M. Young (“Young”).  The foregoing entities and individuals are collectively referred to as the “Reporting Persons.”

PMG VIII, the general partner of USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B, may be deemed to have sole power to vote and sole power to dispose of shares of the issuer directly owned by USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B. Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young are managing members of PMG VIII and may be deemed to have shared power to vote and shared power to dispose of shares of the issuer directly owned by USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B.  

ITEM 2(B).

ADDRESS OF PRINCIPAL OFFICE

The address for each of the Reporting Persons is:

U.S. Venture Partners

2735 Sand Hill Road

Menlo Park, California  94025

ITEM 2(C)

CITIZENSHIP

USVP VIII, USVP VIII AF, USVP EP VIII-A and USVP EP VIII-B are Delaware limited partnerships.  PMG VIII is a Delaware limited liability company.  Connors, Federman, Fu, Krausz, Liddle, Root, Rust and Young are United States citizens.  

ITEM 2(D) AND (E).

TITLE OF CLASS OF SECURITIES AND CUSIP NUMBER

Warrants exercisable for shares of Common Stock

CUSIP  # 02216N105

ITEM 3.

Not Applicable.

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ITEM 4.

OWNERSHIP

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.  

(a)

Amount beneficially owned:

See Row 9 of cover page for each Reporting Person.

(b)

Percent of Class:

See Row 11 of cover page for each Reporting Person.

(c)

Number of shares as to which such person has:

(i)

Sole power to vote or to direct the vote:

See Row 5 of cover page for each Reporting Person.

(ii)

Shared power to vote or to direct the vote:

See Row 6 of cover page for each Reporting Person.

(iii)

Sole power to dispose or to direct the disposition of:

See Row 7 of cover page for each Reporting Person.

(iv)

Shared power to dispose or to direct the disposition of:

See Row 8 of cover page for each Reporting Person.

ITEM 5.

OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following:  x  Yes

ITEM 6.

OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

Please see Item 5.

ITEM 7.

IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY

Not applicable.

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ITEM 8.

IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

Not applicable.

ITEM 9.

NOTICE OF DISSOLUTION OF GROUP.

Not applicable.

ITEM 10.

CERTIFICATION.

Not applicable.

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SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated:  February 9, 2010

PRESIDIO MANAGEMENT GROUP VIII, L.L.C. U.S. VENTURE PARTNERS VIII, L.P. By Presidio Management Group VIII, L.L.C. Its General Partner USVP VIII AFFILIATES FUND, L.P. By Presidio Management Group VIII, L.L.C. Its General Partner USVP ENTREPRENEUR PARTNERS VIII-A, L.P., By Presidio Management Group VIII, L.L.C. Its General Partner USVP ENTREPRENEUR PARTNERS VIII-B, L.P., By Presidio Management Group VIII, L.L.C. Its General Partner

TIMOTHY CONNORS IRWIN FEDERMAN WINSTON FU STEVEN M. KRAUSZ DAVID LIDDLE JONATHAN D. ROOT CHRISTOPHER RUST PHILIP M. YOUNG

By: /s/ Michael Maher                                                     Michael Maher, Chief Financial Officer/Attorney-In- Fact for the above-listed entities*

By: /s/ Michael Maher                                                       Michael Maher, Attorney-In-Fact for the above-listed individuals*

*Signed pursuant to a Power of Attorney already on file with the appropriate agencies.

The original statement shall be signed by each person on whose behalf the statement is filed or his authorized representative. If the statement is signed on behalf of a person by his authorized representative other than an executive officer or general partner of the filing person, evidence of the representative’s authority to sign on behalf of such person shall be filed with the statement, provided, however, that a power of attorney for this purpose which is already on file with the Commission may be incorporated by reference. The name and any title of each person who signs the statement shall be typed or printed beneath his signature.

NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for

other parties for whom copies are to be sent.

Attention: Intentional misstatements or omissions of fact constitute Federal criminal violations (See 18 U.S.C. 1001)

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EXHIBIT INDEX

	Found on Sequentially
Exhibit	Numbered Page
Exhibit A:  Agreement of Joint Filing	20

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EXHIBIT A

Agreement of Joint Filing

The Reporting Persons hereby agree that a single Schedule 13G (or any amendment thereto) relating to the Common Stock of Altus Pharmaceuticals Inc. shall be filed on behalf of each of the Reporting Persons.  Note that copies of the applicable Agreement of Joint Filing are already on file with the appropriate agencies.