Filing Details

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY EACH
REPORTING
PERSON
WITH

SOLE VOTING POWER
2,375,000 shares, except that Foresite Capital Management III, LLC (“FCM III”), the general partner of FCF III, may be deemed to have sole power to vote these shares, and James Tananbaum (“Tananbaum”), the managing member of FCM III, may be deemed to have sole power to vote these shares.

SOLE DISPOSITIVE POWER

2,375,000 shares, except that FCM III, the general partner of FCF III, may be deemed to have sole power to dispose of these shares, and Tananbaum, the managing member of FCM III, may be deemed to have sole power to dispose of these shares.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY EACH
REPORTING
PERSON
WITH

SOLE VOTING POWER
2,375,000 shares, all of which are directly owned by Foresite Capital Fund III, L.P. (“FCF III”).  FCM III, the general partner of FCF III, may be deemed to have sole power to vote these shares, and James Tananbaum (“Tananbaum”), the managing member of FCM III, may be deemed to have sole power to vote these shares.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY EACH
REPORTING
PERSON
WITH

SOLE VOTING POWER
2,375,000 shares, all of which are directly owned by Foresite Capital Fund III, L.P. (“FCF III”).  Tananbaum is the managing member of Foresite Capital Management III, LLC (“FCM III”), which is the general partner of FCF III.  Tananbaum may be deemed to have sole power to vote these shares.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES

1 Tower Place, Suite 300
South San Francisco, California, 94080

NAME OF PERSONS FILING

This Schedule is filed by Foresite Capital Fund III, L.P., a Delaware limited partnership, Foresite Capital Management III, LLC, a Delaware limited liability company, and James Tananbaum. The foregoing entities and individuals are collectively referred to as the “Reporting Persons.”

CITIZENSHIP

See Row 4 of cover page for each Reporting Person.

TITLE OF CLASS OF SECURITIES

Common Stock

CUSIP NUMBER

004449104

If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Amount beneficially owned:

See Row 9 of cover page for each Reporting Person.

Percent of Class:

See Row 11 of cover page for each Reporting Person.

Sole power to vote or to direct the vote:

See Row 5 of cover page for each Reporting Person.

Shared power to dispose or to direct the disposition of:

See Row 8 of cover page for each Reporting Person.

OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS

Not applicable.

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

Under certain circumstances set forth in the limited partnership agreement of FCF III and the limited liability company agreement of FCM III the partners or members, as the case may be, of each of such entities may be deemed to have the right to receive dividends from, or the proceeds from the sale of, shares of the Issuer directly or indirectly owned by each such entity of which they are a partner or member.

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

Not applicable.

IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

Not applicable

NOTICE OF DISSOLUTION OF GROUP.

Not applicable

CERTIFICATION.

By signing below, I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.