-----BEGIN PRIVACY-ENHANCED MESSAGE----- Proc-Type: 2001,MIC-CLEAR Originator-Name: webmaster@www.sec.gov Originator-Key-Asymmetric: MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB MIC-Info: RSA-MD5,RSA, Pmjq+/cZt7bgttlKx2YHWqfY30rIwckhRHmbRfYh9Syap09LWZKuUZL8ULmzy+NT dv8Th3GMLBulaPcw+0FiUw== 0000912057-02-039039.txt : 20021018 0000912057-02-039039.hdr.sgml : 20021018 20021018153136 ACCESSION NUMBER: 0000912057-02-039039 CONFORMED SUBMISSION TYPE: SC 13D/A PUBLIC DOCUMENT COUNT: 3 FILED AS OF DATE: 20021018 GROUP MEMBERS: BIOTECHNOLOGY VALUE FUND II, L.P. GROUP MEMBERS: BVF INC. GROUP MEMBERS: BVF INVESTMENTS, L.L.C. GROUP MEMBERS: BVF PARTNERS L.P. SUBJECT COMPANY: COMPANY DATA: COMPANY CONFORMED NAME: ARENA PHARMACEUTICALS INC CENTRAL INDEX KEY: 0001080709 STANDARD INDUSTRIAL CLASSIFICATION: SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731] IRS NUMBER: 232908305 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: SC 13D/A SEC ACT: 1934 Act SEC FILE NUMBER: 005-59397 FILM NUMBER: 02792671 BUSINESS ADDRESS: STREET 1: 6166 NANCY RIDGE DR CITY: SAN DIEGO STATE: CA ZIP: 92121 BUSINESS PHONE: 8584537200 MAIL ADDRESS: STREET 1: 6166 NANCY RIDGE DR CITY: SAN DIEGO STATE: CA ZIP: 92121 FILED BY: COMPANY DATA: COMPANY CONFORMED NAME: BIOTECHNOLOGY VALUE FUND L P CENTRAL INDEX KEY: 0000918923 STANDARD INDUSTRIAL CLASSIFICATION: INVESTMENT ADVICE [6282] IRS NUMBER: 363924731 STATE OF INCORPORATION: DE FILING VALUES: FORM TYPE: SC 13D/A BUSINESS ADDRESS: STREET 1: 227 W MONROE STREET, SUITE 4800 STREET 2: 227 W MONROE STREET, SUITE 4800 CITY: CHICAGO STATE: IL ZIP: 60606 BUSINESS PHONE: 415-288-23 MAIL ADDRESS: STREET 1: 227 W MONROE STREET, SUITE 4800 STREET 2: 227 W MONROE STREET, SUITE 4800 CITY: CHICAGO STATE: IL ZIP: 60606 SC 13D/A 1 a2091405zsc13da.htm SCHEDULE 13D/A
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

SCHEDULE 13D
Under the Securities Exchange Act of 1934
(Amendment No. 1)⁽¹⁾

Arena Pharmaceuticals, Inc.
(Name of Issuer)

Common Stock
(Title of Class of Securities)

040047 10 2
(CUSIP Number)

Hope Flack
BVF Partners L.P.
227 West Monroe Street, Suite 4800
Chicago, Illinois 60606
(312) 263-7777
(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

October 11, 2002
(Date of Event Which Requires Filing of this Amendment)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ý

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 to whom copies are to be sent.

(Continued on following pages)
(Page 1 of 9 Pages)

(1): 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).

CUSIP No. 040047 10 2

13D

Page 2 of 9 Pages



1	NAME OF REPORTING PERSON: Biotechnology Value Fund, L.P. I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*	(a)	/x/
		(b)	/ /


3	SEC USE ONLY


4	SOURCE OF FUNDS* WC


5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)
			/ /


6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0


		8	SHARED VOTING POWER 2,263,745


		9	SOLE DISPOSITIVE POWER 0


		10	SHARED DISPOSITIVE POWER 2,263,745


11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,263,745


12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*
			/ /


13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 8.2%


14	TYPE OF REPORTING PERSON* PN


*SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 040047 10 2

13D

Page 3 of 9 Pages



1	NAME OF REPORTING PERSON: Biotechnology Value Fund II, L.P. I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*	(a)	/x/
		(b)	/ /


3	SEC USE ONLY


4	SOURCE OF FUNDS* WC


5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)
			/ /


6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0


		8	SHARED VOTING POWER 1,453,102


		9	SOLE DISPOSITIVE POWER 0


		10	SHARED DISPOSITIVE POWER 1,453,102


11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,453,102


12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*
			/ /


13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 5.3%


14	TYPE OF REPORTING PERSON* PN


*SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 040047 10 2

13D

Page 4 of 9 Pages



1	NAME OF REPORTING PERSON: BVF Investments, L.L.C. I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*	(a)	/x/
		(b)	/ /


3	SEC USE ONLY


4	SOURCE OF FUNDS* WC


5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)
			/ /


6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0


		8	SHARED VOTING POWER 3,714,365


		9	SOLE DISPOSITIVE POWER 0


		10	SHARED DISPOSITIVE POWER 3,714,365


11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 3,714,365


12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*
			/ /


13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.4%


14	TYPE OF REPORTING PERSON* OO


SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 040047 10 2

13D

Page 5 of 9 Pages



1	NAME OF REPORTING PERSON: BVF Partners L.P. I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*	(a)	/x/
		(b)	/ /


3	SEC USE ONLY


4	SOURCE OF FUNDS* OO


5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)
			/ /


6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0


		8	SHARED VOTING POWER 7,658,412


		9	SOLE DISPOSITIVE POWER 0


		10	SHARED DISPOSITIVE POWER 7,658,412


11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 7,658,412


12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*
			/ /


13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 27.7%


14	TYPE OF REPORTING PERSON* PN


*SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 040047 10 2

13D

Page 6 of 9 Pages



1	NAME OF REPORTING PERSON: BVF Inc. I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY):


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*	(a)	/x/
		(b)	/ /


3	SEC USE ONLY


4	SOURCE OF FUNDS* OO


5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)
			/ /


6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0


		8	SHARED VOTING POWER 7,658,412


		9	SOLE DISPOSITIVE POWER 0


		10	SHARED DISPOSITIVE POWER 7,658,412


11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 7,658,412


12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*
			/ /


13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 27.7%


14	TYPE OF REPORTING PERSON* IA, CO


*SEE INSTRUCTIONS BEFORE FILLING OUT!

Page 7 of 9 Pages

This Amendment No. 1 to the Statement on Schedule 13D (this "Amendment") is being filed with the Securities and Exchange Commission on behalf of the Biotechnology Value Fund, L.P., a Delaware limited partnership ("BVF"), Biotechnology Value Fund II, L.P., a Delaware limited partnership ("BVF2"), BVF Investments, L.L.C., a Delaware limited liability company ("Investments"), BVF Partners L.P., a Delaware limited partnership ("Partners") and BVF Inc., a Delaware corporation ("BVF Inc." and, together with BVF, BVF2, Investments, and Partners, the "Reporting Persons") with respect to the Common Stock, par value $0.0001 per share (the "Stock"), of Arena Pharmaceuticals, Inc., a Delaware corporation ("Arena"). The principal executive office of Arena is located at 6166 Nancy Ridge Road, San Diego, California 92121.

Item 3 is hereby amended to read in its entirety as follows:

ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

Since August 12, 2002, Partners, in its capacity as (i) general partner of BVF, has purchased on behalf of such limited partnership an aggregate number of 547,925 shares of the Stock for an aggregate consideration of $2,739,625.00, utilizing funds provided by BVF from its working capital pursuant to the terms of its limited partnership agreement with Partners; (ii) general partner of BVF2, has purchased on behalf of such limited partnership an aggregate number of 334,802 shares of the Stock for an aggregate consideration of $1,674,010.00, utilizing funds provided by BVF2 from its working capital pursuant to the terms of its limited partnership agreement with Partners; and (iii) manager of Investments, has purchased on behalf of such limited liability company an aggregate number of 1,161,565 shares of the Stock for an aggregate consideration of $5,807,825.00, utilizing funds provided by Investments from its working capital pursuant to the terms of its operating agreement.

Item 4 is hereby amended to read in its entirety as follows:

ITEM 4. PURPOSE OF TRANSACTIONS.

The sole purpose of the acquisitions of the shares of Stock reported herein was for investment. The Reporting Persons review their investments on an ongoing basis. Such continuing review may result in the Reporting Persons acquiring additional Stock, or selling all or a portion of their Stock, in the open market or in privately negotiated transactions with the Issuer or third parties or maintaining their holdings at current levels. The Reporting Persons are engaged in discussions with representatives of the Issuer regarding representation on the Issuer's Board of Directors. The Reporting Persons may provide constructive input regarding measures intended to maximize shareholder value and, consistent with the investment purpose, may engage in communications with one or more shareholders of the Issuer and/or one or more members of the board of directors, officers or representatives of the Issuer regarding the Issuer. The Reporting Persons' review of their investments and these activities may result in the Reporting Persons formulating plans or making proposals regarding actions set forth in Item 4 of Schedule 13D. The Reporting Persons' decision to acquire or dispose of Stock, hold Stock or take such other actions will depend on market, economic and other conditions, including an ongoing evaluation of the Issuer's financial condition, operations and prospects, the actions of the Issuer's management and the Board and other future developments, regulatory requirements and the relative attractiveness of alternative business and investment opportunities. Such transactions or actions, if any, would be made at such times and in such manner as the Reporting Persons, in their discretion, deem advisable.

The Reporting Persons reserve the right to formulate plans or make proposals, and take such action with respect to their investment in the Issuer, including any or all of the items set forth in paragraphs (a) through (j) of Item 4 of Schedule 13D and any other actions, as they may determine.

Page 8 of 9 Pages

Item 5 is hereby amended to read in its entirety as follows:

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER.

(a): BVF beneficially owns 2,263,745 shares of the Stock, BVF2 beneficially owns 1,453,102 shares of the Stock, Investments beneficially owns 3,714,365 shares of the Stock and each of Partners and BVF Inc. beneficially owns 7,658,412 shares of the Stock, representing approximately 8.2%, 5.3%, 13.4% and 27.7%, respectively, of the aggregate number of shares of common stock outstanding as of July 31, 2002.
(b): Each of BVF, BVF2 and Investments shares with Partners voting and dispositive power over the shares of the Stock each such entity beneficially owns. Partners and BVF Inc. share voting and dispositive power over the 7,658,412 shares of the Stock they beneficially own with, in addition to BVF, BVF2 and Investments, Investment 10, L.L.C., an Illinois limited liability company ("ILL10") and managed account on whose behalf Partners, as investment advisor, purchased such shares. ILL10 specializes in holding biotechnology stocks for investment purposes and its business address is 227 West Monroe Street, Suite 4800, Chicago, Illinois 60606.
(c): There have been no transactions by BVF, BVF2, Investments, Partners or BVF Inc. in securities of the Issuer during the past sixty days, other than those transactions described in Item 3 that are pursuant to the terms and conditions of the Stock Purchase Agreement, attached hereto as Exhibit 2.
(d): ILL10 is entitled to receive dividends and any sale proceeds with respect to shares of the Stock in proportion to its respective ownership interest therein.

Item 6 is hereby amended to read in its entirety as follows:

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF ISSUER.

Partners is the general partner of each of BVF and BVF2 pursuant to limited partnership agreements which authorize Partners, among other things, to invest the funds of BVF and BVF2 in shares of the Stock and to vote, exercise or convert and dispose of such shares. Pursuant to such limited partnership agreements, Partners is entitled to receive fees based on assets under management and allocations based on realized and unrealized gains on such assets. Pursuant to the operating agreement of Investments, Partners is authorized, among other things, to invest the funds of Ziff Asset Management, L.P., the majority member of Investments, in shares of the Stock and to vote, exercise or convert and dispose of such shares and is entitled to receive fees based on assets under management and allocations based on realized and unrealized gains on such assets. Pursuant to an investment management agreement with ILL10, Partners and BVF Inc. have authority, among other things, to invest funds of ILL10 in shares of the Stock and to vote, exercise or convert and dispose of such shares. Pursuant to such investment management agreement, Partners and BVF Inc. receive fees based on assets under management and realized and unrealized gains thereon. BVF Inc. is the general partner of Partners and may be deemed to own beneficially securities over which Partners exercises voting and dispositive power.

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

Exhibit 1—Agreement Regarding Joint Filing

Exhibit 2—Stock Purchase Agreement

Page 9 of 9 Pages

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

Dated:	October 18, 2002

	BIOTECHNOLOGY VALUE FUND, L.P.
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BIOTECHNOLOGY VALUE FUND II, L.P.
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF INVESTMENTS, L.L.C.
	By:	BVF Partners L.P., its manager
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF PARTNERS L.P.
	By:	BVF Inc., its general partner
		By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF INC.
	By:	/s/ MARK N. LAMPERT Mark N. Lampert President

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ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

ITEM 4. PURPOSE OF TRANSACTIONS.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF ISSUER.

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

EX-1 3 a2091405zex-1.htm EXHIBIT 1
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EXHIBIT 1

AGREEMENT REGARDING JOINT FILING

The undersigned, Biotechnology Value Fund, L.P., a Delaware limited partnership, Biotechnology Value Fund II, L.P., a Delaware limited partnership, BVF Investments, L.L.C., a Delaware limited liability company, BVF Partners L.P., a Delaware limited partnership, and BVF Inc., a Delaware corporation, hereby agree and acknowledge that the information required by Schedule 13D, to which this Agreement is attached as an exhibit, is filed on behalf of each of them. The undersigned further agree that any amendments or supplements thereto shall also be filed on behalf of each of them.

Dated:	October 18, 2002

	BIOTECHNOLOGY VALUE FUND, L.P.
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BIOTECHNOLOGY VALUE FUND II, L.P.
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF INVESTMENTS, L.L.C.
	By:	BVF Partners L.P., its manager
		By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF PARTNERS L.P.
	By:	BVF Inc., its general partner
			By:	/s/ MARK N. LAMPERT Mark N. Lampert President
	BVF INC.
	By:	/s/ MARK N. LAMPERT Mark N. Lampert President

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EXHIBIT 1

AGREEMENT REGARDING JOINT FILING
EX-2 4 a2091405zex-2.htm EXHIBIT 2
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EXHIBIT 2

STOCK PURCHASE AGREEMENT

This STOCK PURCHASE AGREEMENT (the "Agreement") is entered into as of October 11, 2002 by and between BB BioVentures LP, a Delaware limited partnership (the "BioVentures Fund"), MPM BioVentures Parallel Fund, L.P., a Delaware limited partnership (the "Parallel Fund"), and MPM Asset Management Investors 1999 LLC, a Delaware limited liability company (the "Co-Investment Fund" and, collectively with the BioVentures Fund and the Parallel Fund, the "Sellers") ("Seller"), and BIOTECHNOLOGY VALUE FUND, L.P., a Delaware limited partnership ("BVF"), BIOTECHNOLOGY VALUE FUND II, L.P., a Delaware limited partnership ("BVF II"), BVF INVESTMENTS L.L.C., a Delaware limited liability company ("BVF Investments") and ZIFF ASSET MANAGEMENT, L.P., a Delaware limited partnership ("Ziff") and collectively with BVF, BVF II and BVF Investments, "BUYER").

WHEREAS, each of the Sellers owns of record and beneficially the number of shares of common stock, par value $.01 per share ("Common Stock"), of Arena Pharmaceuticals, Inc., a Delaware corporation (the "Company") set forth opposite its name on Schedule A attached hereto (collectively, the "Shares");

WHEREAS, each Seller desires to sell the Shares set forth opposite its name on Schedule A to Buyer, and Buyer desires to buy such Shares from Seller, at a price of $5.00 per share and otherwise upon the terms and conditions contained herein.

NOW, THEREFORE, in order to consummate said purchase and sale and in consideration of the mutual agreements set forth herein, and other good and valuable consideration the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree as follows:

SECTION 1. Sale of Shares and Purchase Price.

1.1. Sale of Shares. At the Closing (as defined in Section 1.3 below), each Seller hereby agrees to sell to Buyer, and Buyer hereby agrees to purchase from such Seller, the Shares set forth opposite such Seller's name on Schedule A. At the Closing, subject to the terms and conditions hereof, the Sellers shall deliver, or cause the transfer agent and registrar of the Company to deliver, to Buyer a certificate or certificates representing the Shares set forth opposite such Seller's name on Schedule A, with such signature guarantees and such other documents as may be reasonably required by Buyer to effect a valid transfer of the Shares by the Sellers.

1.2. Purchase Price and Payment. In consideration of the sale by each Seller to Buyer of the Shares set forth opposite such Seller's name on Schedule A and subject to the terms and conditions hereof, Buyer agrees that at the Closing it will deliver to counsel for Sellers, as escrow agent for Sellers (the "Sellers Escrow Agent") $10,221,460 (the "Purchase Price") by wire transfer of immediately available funds. Sellers Escrow Agent shall hold such funds in its trust account on behalf of Sellers, and shall release to each Seller the portion of the Purchase Price set forth opposite such Seller's name on Schedule A by wire transfer of immediately available funds upon Buyer's receipt of certificate(s) representing the Shares sold by such Seller free of any restrictive legends and duly endorsed for transfer to Buyer. Sellers Escrow Agent shall release such funds to the following accounts in the amounts as indicated below:

Boston Private Bank & Trust
Ten Post Office Square
Boston, MA 02109

ABA #011 002 343

Page 1 of 5

Account Name: BB BioVentures LP
Account # 404-5364
Amount: $8,848,170

Account Name: MPM BioVentures Parallel Fund LP
Account # 404-5445
Amount: $1,266,950

Account Name: MPM Asset Management Investors 1999 LLC
Account # 404-5178
Amount: $106,340

1.3. Time and Place of Closing. The closing of the purchase and sale provided for in this Agreement (the "Closing") shall take place at 9:00 a.m. on October 15, 2002, at the offices of Goodwin Procter LLP, Exchange Place, Boston, Massachusetts 02109 or at such other time or place as Buyer and the Sellers may mutually agree.

SECTION 2. Representations and Warranties of the Sellers. As a material inducement to Buyer to enter into this Agreement and consummate the transactions contemplated hereby, each Seller severally, but not jointly, hereby makes to Buyer each of the representations and warranties set forth in this Section 2.

2.1. Authority. Such Seller has full right, authority, power and capacity, corporate or otherwise, to enter into this Agreement and each agreement, document and instrument to be executed and delivered by such Seller pursuant to this Agreement and to carry out the transactions contemplated hereby and thereby. This Agreement and each agreement, document and instrument executed and delivered by such Seller pursuant to this Agreement constitutes a valid and binding obligation of such Seller, enforceable in accordance with their respective terms. Such Seller has full power and authority to transfer, sell and deliver the Shares to Buyer pursuant to this Agreement. Such Seller is not subject to any law, rule or regulation or a party to, subject to or bound by any agreement or judgment, order, writ, prohibition, injunction or decree of any court or other governmental authority which would prevent or restrict the transfer, sale and delivery to Buyer of the Shares pursuant to the terms of this Agreement.

2.2. Title to Shares. Each Seller is the sole legal and beneficial owner and holder of the number of Shares indicated in the preamble to this Agreement and has good title thereto, free and clear of any liens, security interests, claims, charges or other encumbrances. Each Seller has not, directly or indirectly, pledged, encumbered, assigned, transferred, conveyed, disposed of or terminated, in whole or in part, any of its right, title and interest in and to the Shares.

2.3 No Required Consents. No filing with, notice to, or consent or approval of, or other action by, any federal, state or other governmental agency, authority, administrative or regulatory body, arbitrator, court or other tribunal, foreign or domestic, is required in connection with execution, delivery and performance of this Agreement by such Seller.

2.4 Status of Shares. Each Seller has held the Shares set forth opposite such Seller's name on Schedule A for at least the period provided in Rule 144(k) under the Securities Act of 1933, as amended ("Rule 144"), and no Seller is, nor has been for the past 90 days, an "affiliate" of the Company, within the meaning of Rule 144.

2.5 Nonpublic Information. The Sellers have implemented and maintained policies and procedures as described in Rule 10b5-1(c)(2) of the Securities Exchange Act of 1934, as amended, and no person who made the investment decision to sell the Shares for each Seller was aware of adverse material non-public information with respect to the Company.

Page 2 of 5

2.6. Finder's Fee. Such Seller has not incurred or become liable for any broker's commission or finder's fee relating to or in connection with the transactions contemplated by this Agreement.

SECTION 3. Representations and Warranties of Buyer.

As a material inducement to the Sellers to enter into this Agreement and consummate the transactions contemplated hereby, Buyer hereby makes to the Sellers each of the representations and warranties set forth in this Section 3.

3.1. Authority. Buyer has full right, authority, power and capacity, corporate or otherwise, to enter into this Agreement and each agreement, document and instrument to be executed and delivered by Buyer pursuant to this Agreement and to carry out the transactions contemplated hereby and thereby. This Agreement and each agreement, document and instrument executed and delivered by Buyer pursuant to this Agreement constitutes a valid and binding obligation of Buyer, enforceable in accordance with their respective terms. Buyer is not subject to any law, rule or regulation or a party to, subject to or bound by any agreement or judgment, order, writ, prohibition, injunction or decree of any court or other governmental authority which would prevent the transfer, sale and delivery to Buyer of the Shares pursuant to the terms of this Agreement.

3.2. Finder's Fee. Buyer has not incurred or become liable for any broker's commission or finder's fee relating to or in connection with the transactions contemplated by this Agreement.

3.3. Status of Buyer. The Buyer is a sophisticated investor with respect to the Shares, has adequate information concerning the business and financial condition of the Company to make an informed decision regarding the purchase of the Shares. Buyer acknowledges that Michael Steinmetz, a Partner and employee of MPM Asset Management LLC, is a director of the Company and may possess material nonpublic information regarding the Company not known to Buyer or any person who made the investment decision to sell the Shares for each Seller (the "Excluded Information"), including, without limitation, information received from the Company on a confidential basis, information received by him in his capacity as a director of the Company, and information received on a privileged basis from third parties, attorneys, financial advisors or other agents representing the Company or third parties. Buyer has independently and without reliance upon the Sellers made its own analysis and decision to enter into this Agreement, except that Buyer has relied upon the representations, warranties, covenants and agreements of the Sellers expressly set forth in this Agreement. The Buyer acknowledges that the Sellers have not made and does not make any representation or warranty, whether express or implied, of any kind or character except as expressly set forth in this Agreement. Buyer acknowledges that the purchase of the Shares by Buyer from the Sellers is irrevocable, and that Buyer shall have no recourse to the Sellers except with respect to remedies resulting from breaches of this Agreement or as otherwise expressly set forth herein or as provided by law.

3.4. Excluded Information.

(a): Buyer hereby:

(i) agrees that Mr. Steinmetz, in his individual capacity or in his capacity as director of the Company or an affiliate of the Sellers, nor the Sellers, nor their respective directors, officers, trustees, employees, beneficiaries, attorneys, agents or representatives shall have any liability to Buyer or its affiliates with respect to the existence, possession or non-disclosure of any Excluded Information, whether arising directly or indirectly, primarily or secondarily, including as a matter of contribution, indemnification, set-off, rescission, or reimbursement;

(ii) waives any right, claim or cause of action, at law or in equity, arising from or relating to, directly or indirectly, the existence, possession or non-disclosure of any Excluded Information, including without limitation pursuant to Sections 10(b) and 20A of the Securities Exchange Act of 1934, as amended (the "Act"), or the rules and regulations promulgated by the Securities and

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Exchange Commission under the Act, and relinquishes all rights and remedies accorded by applicable law to a buyer of securities with respect to the Shares to the maximum extent permitted by law, as well as all rights to participate in any claim, action or remedy others may now or hereafter have with respect to the foregoing; and

(iii) with respect to the purchase and sale of the Shares, releases and discharges Mr. Steinmetz, the Sellers, and their respective directors, officers, trustees, employees, beneficiaries, attorneys, agents, representatives, successors and assigns (each a "Released Party") of and from any and all suits, demands, obligations, liabilities, claims and causes of action, contingent or otherwise, of every kind and nature, at law and in equity, which Buyer and/or its affiliates, successors or assigns may have against any Released Party, to the maximum extent permitted by law and to the extent arising from or in connection with the existence, possession or non-disclosure of any Excluded Information, whether asserted, unasserted, absolute, contingent, known or unknown.

(b) Buyer hereby represents to each Released Party that (i) it has not assigned any claim or possible claim against the Released Parties, (ii) it fully intends to release all claims against the Released Parties as set forth above, and (iii) it has been advised by, and has consulted with, counsel with respect to the execution and delivery of this Agreement and has been fully apprised of the consequences of the waivers and releases set forth in this Section 3.4.

SECTION 4. Conditions

4.1. Conditions to the Obligations of Buyer. Buyer's obligation to purchase the Shares at the Closing is subject to the satisfaction, at or prior to the Closing, of the following conditions precedent:

(a) Representations and Warranties. Each of the representations and warranties of the Sellers contained in Section 2 of this Agreement shall be true and correct as of the date of this Agreement and as of the Closing.

(b) Title; Stock Certificates. On the date of the Closing, each Seller shall have transferred to Buyer good title to the Shares set forth opposite its name on Schedule A, free and clear of any liens, security interests, claims, charges or other encumbrances and shall have delivered to Buyer one or more stock certificates (which shall be free of any restrictive legends) in such name(s) as Buyer may direct representing the Shares, either directly or through the facilities of The Depository Trust Company, as requested by Buyer.

4.2. Conditions to the Obligations of Seller. Each Seller's obligation to sell the Shares set forth opposite its name on Schedule A at the Closing is subject to the satisfaction, at or prior to the Closing, of the following conditions precedent:

(a) Representations and Warranties. Each of the representations and warranties of Buyer contained in Section 3 of this Agreement shall be true and correct as of the date of this Agreement and as of the Closing.

(b) Payment for Shares. Such Seller shall have received from Buyer payment in full of the portion of the Purchase Price set forth opposite such Seller's name on Schedule A.

SECTION 5. Miscellaneous.

5.1. Governing Law. This Agreement shall be construed under and governed by the internal laws of the State of Delaware without regard to its conflict of laws provisions.

5.2. Entire Agreement. This Agreement is complete, reflects the entire agreement of the parties with respect to its subject matter, and supersedes all previous written or oral negotiations, commitments and writings. No promises, representations, understandings, warranties or agreements have been made

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by any of the parties hereto and all inducements to the making of this Agreement relied upon by either party hereto have been expressed herein.

5.3. Assignability; Binding Effect. This Agreement may not be assigned by either party without the prior written consent of the other. This Agreement shall be binding upon and enforceable by, and shall inure to the benefit of, the parties hereto and their respective successors and assigns.

5.4. Headings. The headings in this Agreement are for convenience only and shall not affect the construction or interpretation of any term or provision hereof.

5.5. Counterparts. For convenience of the parties and to facilitate execution, this Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same document.

5.6. Amendment; Waiver. This Agreement may not be amended or modified, nor may compliance with any condition set forth herein be waived, except by a writing duly and validly executed by each party hereto, or in the case of a waiver, the party waiving compliance.

5.7. Fees and Expenses. Each of the parties will bear its own expenses in connection with the negotiation of, and the consummation of the transactions contemplated by, this Agreement.

5.10. Consent to Jurisdiction. Each of the parties hereby consents to personal jurisdiction, service of process and venue in the federal or state courts of the State of Delaware for any claim, suit or proceeding arising under this Agreement.

5.11. Severability. If any provision of this Agreement shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not be affected or impaired thereby.

5.12. Third Party Beneficiaries. With respect to Section 3.4 hereof, it is the intent of Seller and Buyer that each Released Party be a third party beneficiary of this Agreement.

[SIGNATURE PAGE FOLLOWS]

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IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date set forth above.

		BB BIOVENTURES LP
		By:	BAB BioVentures LP, its General Partner
		By:	BAB BioVentures NV, its General Partner
		By:	/s/ LUKE EVNIN Name: Luke Evnin
		MPM BIOVENTURES PARALLEL FUND, L.P.
		By:	MPM BioVentures I LP, its General Partner
		By:	MPM BioVentures I LLC, its General Partner
		By:	/s/ LUKE EVNIN Name: Luke Evnin Title: Manager
		MPM ASSET MANAGEMENT INVESTORS 1999 LLC
		By:	/s/ LUKE EVNIN Name: Luke Evnin Title: Manager
		BIOTECHNOLOGY VALUE FUND, L.P.
		By:	BVF Partners LP, its general partner
		By:	BVF Inc., its general partner
		By:	/s/ MARK LAMPERT Name: Mark Lampert Title: President

		BIOTECHNOLOGY VALUE FUND II, L.P.
		By:	BVF Partners LP, its general partner
		By:	BVF Inc., its general partner
		By:	/s/ MARK LAMPERT Name: Mark Lampert Title: President
		BVF INVESTMENTS L.L.C.
		By:	BVF Partners LP, its member
		By:	BVF Inc., its general partner
		By:	/s/ MARK LAMPERT Name: Mark Lampert Title: President
		ZIFF ASSET MANAGEMENT, L.P.
		By:	BVF Inc., its attorney-in-fact
		By:	/s/ MARK LAMPERT Name: Mark Lampert Title: President

SCHEDULE A

Seller	Number of Shares Owned and Being Sold	Purchase Price
BB BioVentures LP	1,769,634	$	8,848,170
MPM Asset Management Investors 1999 LLC	253,390	$	1,266,950
MPM BioVentures Parallel Fund, L.P.	21,268	$	106,340
TOTAL	2,044,292	$	10,221,460

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EXHIBIT 2

STOCK PURCHASE AGREEMENT
SCHEDULE A
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