UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 Epix Pharmaceuticals, Inc. (Name of Issuer) Common Stock, par value $0.01 per share (Title of Class of Securities) 26881Q309 (CUSIP Number) May 7, 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: [ ] Rule 13d-1(b) [X] Rule 13d-1(c) [ ] 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 the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for 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). Page 1 of 11 Pages CUSIP No. 26881Q309 13G Page 2 of 11 Pages ------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS Highbridge International LLC ------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) [X] (b) [ ] ------------------------------------------------------------------------------- (3) SEC USE ONLY ------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands, British West Indies ------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ---------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 4,664,461 shares of Common Stock OWNED BY ---------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ---------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) [ ] ------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.24% ------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (see instructions) OO ------------------------------------------------------------------------------- CUSIP No. 26881Q309 13G Page 3 of 11 Pages ------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS Highbridge Capital Management, LLC ------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) [X] (b) [ ] ------------------------------------------------------------------------------- (3) SEC USE ONLY ------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware ------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ---------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 4,664,461 shares of Common Stock OWNED BY ---------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ---------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) [ ] ------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.24% ------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (see instructions) OO ------------------------------------------------------------------------------- CUSIP No. 26881Q309 13G Page 4 of 11 Pages ------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS Glenn Dubin ------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) [X] (b) [ ] ------------------------------------------------------------------------------- (3) SEC USE ONLY ------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States ------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ---------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 4,664,461 shares of Common Stock OWNED BY ---------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ---------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) [ ] ------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.24% ------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (see instructions) IN ------------------------------------------------------------------------------- CUSIP No. 26881Q309 13G Page 5 of 11 Pages ------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS Henry Swieca ------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see instructions) (a) [X] (b) [ ] ------------------------------------------------------------------------------- (3) SEC USE ONLY ------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States ------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 0 SHARES ---------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 4,664,461 shares of Common Stock OWNED BY ---------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 0 REPORTING ---------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,664,461 shares of Common Stock ------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions) [ ] ------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.24% ------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (see instructions) IN ------------------------------------------------------------------------------- CUSIP No. 26881Q309 13G Page 6 of 11 Pages Item 1. (a) Name of Issuer Epix Pharmaceuticals, Inc. (the "Company") (b) Address of Issuer's Principal Executive Offices 4 Maguire Road Lexington, Massachusetts 02421 Item 2(a). Name of Person Filing Item 2(b). Address of Principal Business Office Item 2(c). Citizenship HIGHBRIDGE INTERNATIONAL LLC c/o Harmonic Fund Services The Cayman Corporate Centre, 4th Floor 27 Hospital Road Grand Cayman, Cayman Islands, British West Indies Citizenship: Cayman Islands, British West Indies HIGHBRIDGE CAPITAL MANAGEMENT, LLC 9 West 57th Street, 27th Floor New York, New York 10019 Citizenship: State of Delaware GLENN DUBIN c/o Highbridge Capital Management, LLC 9 West 57th Street, 27th Floor New York, New York 10019 Citizenship: United States HENRY SWIECA c/o Highbridge Capital Management, LLC 9 West 57th Street, 27th Floor New York, New York 10019 Citizenship: United States Item 2(d) Title of Class of Securities Common Stock, $0.01 par value ("Common Stock") Item 2(e) CUSIP Number 26881Q309 Item 3. If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a: (a) [ ] Broker or dealer registered under Section 15 of the Act (15 U.S.C. 78o). (b) [ ] Bank as defined in Section 3(a)(6) of the Act (15 U.S.C. 78c). (c) [ ] Insurance company as defined in Section 3(a)(19) of the Act (15 U.S.C. 78c). CUSIP No. 26881Q309 13G Page 7 of 11 Pages (d) [ ] Investment company registered under Section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8). (e) [ ] An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E); (f) [ ] An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F); (g) [ ] A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G); (h) [ ] A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813); (i) [ ] A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3); (j) [ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(J). If this statement is filed pursuant to Rule 13d-1(c), check this box. [X] 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: As of the date of this filing, (i) Highbridge International LLC beneficially owns 4,664,461 shares of Common Stock and (ii) each of Highbridge Capital Management, LLC, Glenn Dubin and Henry Swieca may be deemed the beneficial owner of the 4,664,461 shares of Common Stock beneficially owned by Highbridge International LLC. Highbridge Capital Management, LLC is the trading manager of Highbridge International LLC. Glenn Dubin is the Chief Executive Officer of Highbridge Capital Management, LLC. Henry Swieca is the Chief Investment Officer of Highbridge Capital Management, LLC. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of shares of Common Stock owned by another Reporting Person. In addition, each of Highbridge Capital Management, LLC, Glenn Dubin and Henry Swieca disclaims beneficial ownership of shares of Common Stock held by Highbridge International LLC. (b) Percent of class: The Company's current report on Form 8-K filed on May 7, 2009, indicates that as of May 7, 2009, after giving effect to the issuance of the 32,828,421 shares of common stock in connection with the Company's exchange offer of Common Stock, cash and contingent value rights in exchange for the Company's existing 3% Convertible Senior Notes due 2024, there were 74,775,862 shares of Common Stock issued and outstanding. Therefore, based on the Company's outstanding shares of Common Stock (i) Highbridge International LLC may be deemed to beneficially own 6.24% of the outstanding shares of Common Stock of the Company and (ii) each of Highbridge Capital Management, LLC, Glenn Dubin and Henry Swieca may be deemed to beneficially own 6.24% of the outstanding shares of Common Stock of the Company. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of shares of Common Stock owned by another Reporting Person. CUSIP No. 26881Q309 13G Page 8 of 11 Pages (c) Number of shares as to which such person has: (i) Sole power to vote or to direct the vote 0 (ii) Shared power to vote or to direct the vote See Item 4(a) (iii) Sole power to dispose or to direct the disposition of 0 (iv) Shared power to dispose or to direct the disposition of See Item 4(a) Item 5. Ownership of Five Percent or Less of a Class Not applicable. Item 6. Ownership of More than Five Percent on Behalf of Another Person Not applicable. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person Not applicable. Item 8. Identification and Classification of Members of the Group See Exhibit I. Item 9. Notice of Dissolution of Group Not applicable. Item 10. Certification By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and CUSIP No. 26881Q309 13G Page 9 of 11 Pages 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. Exhibits: Exhibit I: Joint Filing Agreement, dated as of May 12, 2009, by and among Highbridge International LLC, Highbridge Capital Management, LLC, Glenn Dubin and Henry Swieca. CUSIP No. 26881Q309 13G Page 10 of 11 Pages SIGNATURES After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information with respect to it set forth in this statement is true, complete, and correct. Dated: May 12, 2009 HIGHBRIDGE CAPITAL MANAGEMENT, LLC HIGHBRIDGE INTERNATIONAL LLC By: Highbridge Capital Management, LLC its Trading Manager By: /s/ John Oliva ---------------------------- Name: John Oliva By: /s/ John Oliva Title: Managing Director ------------------------------- Name: John Oliva Title: Managing Director /s/ Henry Swieca /s/ Glenn Dubin ----------------------------- --------------------------- HENRY SWIECA GLENN DUBIN CUSIP No. 26881Q309 13G Page 11 of 11 Pages EXHIBIT I JOINT FILING AGREEMENT This will confirm the agreement by and among the undersigned that the Schedule 13G filed with the Securities and Exchange Commission on or about the date hereof with respect to the beneficial ownership by the undersigned of the shares of Common Stock, $0.01 par value, of Epix Pharmaceuticals, Inc., is being filed, and all amendments thereto will be filed, on behalf of each of the persons and entities named below in accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. Dated as of May 12, 2009 HIGHBRIDGE CAPITAL MANAGEMENT, LLC HIGHBRIDGE INTERNATIONAL LLC By: Highbridge Capital Management, LLC its Trading Manager By: /s/ John Oliva ----------------------------- By: /s/ John Oliva Name: John Oliva -------------------------------- Title: Managing Director Name: John Oliva Title: Managing Director /s/ Henry Swieca /s/ Glenn Dubin -------------------------------- ----------------------------- HENRY SWIECA GLENN DUBIN