UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 3)*

(Name of issuer)

(Title of class of securities)

(CUSIP number)

(Date of event which requires filing of this statement)

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

¨ Rule 13d-1(b)

x Rule 13d-1(c)

¨ Rule 13d-1(d)

The information required in 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).

SCHEDULE 13G

SCHEDULE 13G

SCHEDULE 13G

SCHEDULE 13G

SCHEDULE 13G

SCHEDULE 13G

This Amendment No. 3 (“Amendment No. 3”) amends and supplements the statement on Schedule 13G initially filed on June 10, 2009 (the “Original Filing”), as amended on February 16, 2010 (“Amendment No. 1”) and November 1, 2010 (“Amendment No. 2”). The Original Filing remains in effect except to the extent that it is amended, restated or superseded by information contained in Amendment No. 1, Amendment No. 2 or this Amendment No. 3. Capitalized terms used and not defined in this Amendment No. 3 have the meanings set forth in the Original Filing, Amendment No. 1 or Amendment No. 2.

Item 2(a) is hereby restated as follows:

This Schedule 13G is jointly filed by Boxer Capital, LLC (“Boxer Capital”), Boxer Asset Management Inc. (“Boxer Management”), MVA, Neil Reisman, Ivan Lieberburg and Joseph Lewis (together with Boxer Capital and Boxer Management, MVA, Neil Reisman and Ivan Lieberburg the “Reporting Persons”). Boxer Management is the managing member and majority owner of Boxer Capital. Joseph Lewis is the sole indirect owner and controls Boxer Management. Messrs. Reisman and Lieberburg are employed by Tavistock Life Sciences Company, which is a Delaware corporation and an affiliate of Boxer Capital. MVA is the independent, personal investment vehicle of certain employees of Boxer Capital and Tavistock Life Sciences Company. As such, MVA is not controlled by Boxer Capital, Boxer Management or Joseph Lewis.

Item 2(b) is hereby restated as follows:

The principal business address of the Boxer Capital, MVA, Neil Reisman and Ivan Lieberburg is 445 Marine View Avenue, Suite 100, Del Mar, CA 92014. The principal business address of both Boxer Management and Joseph Lewis is: c/o Cay House P.O. Box N-7776 E.P. Taylor Drive Lyford Cay, New Providence, Bahamas.

Item 2(c) is hereby restated as follows:

Boxer Capital is a limited liability company organized under the laws of Delaware. Boxer Management is organized under the laws of the Bahamas. Neil Reisman and Ivan Lieberburg are citizens of the United States. Joseph Lewis is a citizen of the United Kingdom. MVA is a limited liability company organized under the laws of Delaware.

Item 4 is hereby restated as follows:

Boxer Capital, Boxer Management and Joseph Lewis beneficially own 629,801* Common Shares, the sum 469,801 Common Shares and 160,000 Common Shares underlying currently exercisable warrants to purchase Common Shares (the “Warrants”). MVA beneficially owns 15,000* Common Shares, the sum of 10,000 Common Shares and 5,000 Common Shares underlying Warrants. Neil Reisman beneficially owns 4,000* Common Shares. Ivan Lieberburg beneficially owns 100* Common Shares.

The Common Shares beneficially owned by Boxer Capital, Boxer Management and Joseph Lewis represent 6.35% of the Issuer’s outstanding Common Shares. The Common Shares beneficially owned by MVA represent 0.15% of the Issuer’s outstanding Common Shares. The Common Shares beneficially owned by Neil Reisman represent 0.0% of the Issuer’s outstanding Common Shares. The Common Shares beneficially owned by Ivan Lieberburg represent 0.0% of the Issuer’s outstanding Common Shares.

MVA has the sole power to vote the 15,000* Common Shares it beneficially owns. Neil Reisman has the sole power to vote the 4,000* Common Shares he beneficially owns. Ivan Lieberburg has the sole power to vote the 100* Common Shares he beneficially owns. Boxer Capital, Boxer Management and Joseph Lewis do not have the sole power to dispose or direct the disposition of any Common Shares.

Boxer Capital, Boxer Management and Joseph Lewis have shared voting power with respect to the 629,801* Common Shares they beneficially own. MVA, Neil Reisman and Ivan Lieberburg do not have shared power to vote or direct the vote of any Common Shares.

MVA has the sole power to dispose of the 15,000* Common Shares it beneficially owns. Neil Reisman has the sole power to dispose of the 4,000* Common Shares he beneficially owns. Ivan Lieberburg has the sole power to dispose of the 100* Common Shares he beneficially owns. Boxer Capital, Boxer Management and Joseph Lewis do not have the sole power to dispose or direct the disposition of any Common Shares.

Boxer Capital, Boxer Management and Joseph Lewis have shared dispositive power with respect to the 629,801* Common Shares they beneficially own. MVA, Neil Reisman and Ivan Lieberburg do not have shared power to dispose of or direct the disposition of any Common Shares.

Not applicable.

Item 6 is restated as follows:

Only Boxer Capital has the right to receive dividends and the proceeds from sale of the Common Shares held by the Boxer Capital. Only MVA has the right to receive dividends and the proceeds from sale of the Common Shares held by the MVA. Messrs. Reisman and Lieberburg each have the sole right to receive dividends and proceeds from the sale of the Common Shares directly owned by them, which are held by each of them in their respective personal accounts. See Item 4 above.

(c) 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 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.

Exhibits

SIGNATURE

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.