REGISTRATION RIGHTS AGREEMENT DATED MAY 25, 2004



 Exhibit 4.6 
  

OSCIENT PHARMACEUTICALS CORPORATION 
 31⁄2% Senior Convertible Notes due 2011 
 REGISTRATION RIGHTS AGREEMENT 
 May 25, 2004 
  
 Smithfield Fiduciary LLC 
 c/o Highbridge Capital Management, LLC 

9 West 57th Street, 27th Floor 
 New York, NY 10019

  
 Ladies and Gentlemen: 
  
 Oscient Pharmaceuticals Corporation, a Massachusetts corporation (the
“Company”), proposes to issue and sell (such issuance and sale, the “Initial Placement”) to the Initial Purchaser (as defined below), upon the terms set forth in a purchase agreement, dated May 25, 2004 (the
“Purchase Agreement”), $6,000,000 aggregate principal amount, plus an option, subject to the terms and conditions of the Purchase Agreement, (the “Option”) to purchase up to an additional $3,000,000 aggregate
principal amount, of its 31⁄2% Senior Convertible Notes due 2011 (the “Securities”). The Securities will be convertible into shares of Common Stock (as defined herein), at the conversion price set forth in the Offering Memorandum
(as defined herein), as the same may be adjusted from time to time pursuant to the Indenture (as defined herein). As an inducement to you to enter into the Purchase Agreement and in satisfaction of a condition to your obligations thereunder, the
Company agrees with you, (i) for your benefit and (ii) for the benefit of the Holders (as defined herein) from time to time of the Securities and the shares of Common Stock issuable upon conversion of the Securities, as follows: 
  
 1. Definitions. Capitalized terms used herein without definition shall have the
respective meanings set forth in the Purchase Agreement. As used in this Agreement, the following capitalized terms shall have the following meanings: 
  
 “Affiliate” of any specified person means any other person directly or indirectly controlling or controlled by or under direct or
indirect common control with such specified person. For the purposes of this definition, “control” (including, with correlative meanings, the terms “controlling,” “controlled by” and “under common control
with”), as used with respect to any person, shall mean the possession, directly or indirectly, of the power to direct or cause the direction of the management or policies of such person whether through the ownership of voting securities or by
agreement or otherwise. 
  
 “Business Day” has
the meaning set forth in the Indenture. 
  
 “Closing
Date” means the date of the closing of the sale of the Firm Securities as contemplated by the Purchase Agreement. 
  
 “Common Stock” means the common stock, par value $0.10 per share, of the Company, as it exists on the date of this Agreement and any
other shares of capital stock or other securities of the Company into which such Common Stock may be reclassified or changed, together with 

  









 
any and all other securities which may from time to time be issuable upon conversion of Securities. 
  
 “Company” has the meaning set forth in the preamble hereto.

  
 “Exchange Act” means the Securities Exchange
Act of 1934, as amended, and the rules and regulations of the SEC promulgated thereunder. 
  
 “Holder” means a person who is a holder or beneficial owner of any Securities or shares of Common Stock issuable upon conversion of Securities; provided that, unless otherwise expressly stated
herein, only registered holders of Securities or Common Stock issued on conversion thereof shall be counted for purposes of calculating any proportion of holders entitled to take any action or give notice pursuant to this Agreement. 
  
 “Holder Information” with respect to any Holder means
information with respect to such Holder required to be included in any Shelf Registration Statement or the related Prospectus pursuant to the Securities Act and which information is included therein in reliance upon and in conformity with
information furnished to the Company in writing by such Holder for inclusion therein. 
  
 “Indenture” means the Indenture relating to the Securities, to be dated as of May 10, 2004, and to be entered into between the Company and U.S. Bank National Association, as Trustee, as the same may
be amended from time to time in accordance with the terms thereof. 
  
 “Initial Placement” has the meaning set forth in the preamble hereto. 
  
 “Initial Purchaser” means Smithfield Fiduciary LLC. 
  
 “Liquidated Damages” has the meaning set forth in Section 2(e) hereof. 
  
 “Liquidated Damages Payment Date” means each April 15 and
October 15. 
  
 “Losses” has the meaning set
forth in Section 5(d) hereof. 
  
 “Majority
Holders” means the Holders of a majority of the then outstanding aggregate principal amount of Securities being registered under a Shelf Registration Statement; provided that Holders of the shares of Common Stock issued upon
conversion of Securities shall be deemed to be Holders of the aggregate principal amount of Securities from which such Common Stock was converted; and provided further, that Securities or shares of Common Stock which have been sold or
otherwise transferred pursuant to the Shelf Registration Statement shall not be included in the calculation of Majority Holders. 
  
 “NASD” means the National Association of Securities Dealers, Inc. 
  
 “Notice and Questionnaire” means a Selling Securityholder Notice and Questionnaire substantially in the
form of Annex A to the Offering Memorandum. 
  

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 “Notice Holder” means any Holder of Transfer Restricted Securities that has delivered a
properly completed and signed Notice and Questionnaire to the Company in accordance with Section 2(b) hereof. 
  
 “Offering Memorandum” in the Purchase Agreement. 
  

“Option” has the meaning set forth in the preamble hereto. 
  
 “Person” has the meaning set forth in the Indenture. 
  
 “Prospectus” means the prospectus included in any Shelf
Registration Statement (including, without limitation, a prospectus that discloses information previously omitted from a prospectus filed as part of an effective registration statement in reliance upon Rule 430A under the Securities Act), as amended
or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Securities or shares of Common Stock issuable upon conversion thereof covered by such Shelf Registration Statement, and all amendments and
supplements to such prospectus, including all documents incorporated or deemed to be incorporated by reference in such prospectus. 
  
 “Purchase Agreement” has the meaning set forth in the preamble hereto. 
  
 “Questionnaire Deadline” has the meaning set forth in Section 2(b) hereof. 
  
 “Record Holder” means each person who is registered on the
books of the registrar as the holder of Securities at the close of business on April 1 and October 1 immediately preceding such Liquidated Damages Payment Date. 
  

“Registration Default” has the meaning set forth in Section 2(e) hereof. 
  
 “Rule 144” means Rule 144 under the Securities Act (or any similar provision then in force). 
  
 “Rule 144A” means Rule 144A under the Securities Act (or any
successor provision promulgated by the SEC). 
  
 “Rule
144(k)” means Rule 144(k) under the Securities Act (or any successor provision promulgated by the SEC). 
  
 “Rule 415” means Rule 415 under the Securities Act (or any successor provision promulgated by the SEC). 
  
 “SEC” means the Securities and Exchange Commission.

  
 “Securities” has the meaning set forth in the
preamble hereto. 
  
 “Securities Act” means the
Securities Act of 1933, as amended, and the rules and regulations of the SEC promulgated thereunder. 
  
 “Shelf Registration” means a registration effected pursuant to Section 2 hereof. 
  

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 “Shelf Registration Period” has the meaning set forth in Section 2(c) hereof.

  
 “Shelf Registration Statement” means any
“shelf” registration statement of the Company filed pursuant to the provisions of Section 2 hereof which covers the Transfer Restricted Securities on Form S-3 or on another appropriate form (as determined by the Company) for an offering to
be made on a delayed or continuous basis pursuant to Rule 415 and all amendments and supplements to such registration statement, including post-effective amendments, in each case including the Prospectus contained therein, all exhibits thereto and
all documents incorporated or deemed to be incorporated by reference therein. 
  
 “Suspension Period” has the meaning set forth in Section 2(d) hereof. 
  
 “Transfer Restricted Securities” means each Security and each share of Common Stock issuable upon conversion thereof (and any security
issued with respect thereto upon any stock dividend, split or similar event) until the earliest of the date on which such Security or share of Common Stock, or any security issued with respect thereto upon any stock dividend, split or similar event,
as the case may be: (i) has been transferred pursuant to a Shelf Registration Statement or another registration statement covering such Security or share of Common Stock which has been filed with the SEC pursuant to the Securities Act, in either
case after such registration statement has become effective and while such registration statement is effective under the Securities Act; (ii) has been transferred pursuant to Rule 144 (or any similar provision then in force); (iii) may be sold or
transferred pursuant to Rule 144(k) (or any successor provision promulgated by the SEC); or (iv) ceases to be outstanding. Notwithstanding the foregoing, each Security and each share of Common Stock issuable upon conversion thereof (and any security
issued with respect thereto upon any stock dividend, split or similar event) that has not previously ceased to be a Transfer Restricted Security pursuant to the previous sentence shall cease to be a Transfer Restricted Security on the date that is
two (2) years after the later of the Closing Date or the latest Option Closing Date (as defined in the Purchase Agreement). 
  
 “Trustee” means the trustee with respect to the Securities under the Indenture. 
  
 All references in this Agreement to financial statements and schedules and
other information which is “contained,” “included,” or “stated” in the Shelf Registration Statement, any preliminary Prospectus or Prospectus (and all other references of like import) shall be
deemed to mean and include all such financial statements and schedules and other information incorporated or deemed to be incorporated by reference in such Shelf Registration Statement, preliminary Prospectus or Prospectus, as the case may be; and
all references in this Agreement to amendments or supplements to the Shelf Registration Statement, any preliminary Prospectus or Prospectus shall be deemed to mean and include any document filed with the SEC under the Exchange Act, after the date of
such Shelf Registration Statement, preliminary Prospectus or Prospectus, as the case may be, which is incorporated or deemed to be incorporated by reference therein. 
  

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 2. Shelf Registration Statement. 
  
 (a) The Company shall, at its expense, prepare and file with the SEC within 90 days following the Closing Date a Shelf
Registration Statement with respect to resales of the Transfer Restricted Securities by the Holders from time to time on a delayed or continuous basis pursuant to Rule 415 and in accordance with the methods of distribution set forth in such Shelf
Registration Statement and thereafter shall use its reasonable best efforts to cause such Shelf Registration Statement to be declared effective under the Securities Act within 210 days after the Closing Date; provided that if any Securities
are issued upon exercise of the Option granted to the Initial Purchaser in the Purchase Agreement and the date on which such Securities are issued occurs after the Closing Date, the Company will take such steps, prior to the effective date of the
Shelf Registration Statement, to ensure that such Securities issued upon an exercise of the Option and the shares of Common Stock issuable upon conversion thereof are included in the Shelf Registration Statement on the same terms as the Securities
issued on the Closing Date. The Company shall supplement or amend the Shelf Registration Statement if required by the rules, regulations or instructions applicable to the registration form used by the Company for the Shelf Registration Statement, or
by the Securities Act, the Exchange Act or the SEC. 
  
 (b) (i)
The Company shall name each Holder that delivers a properly completed and signed Notice and Questionnaire to the Company as a selling security holder in the Shelf Registration Statement. A Holder of Transfer Restricted Securities may include such
securities in the Shelf Registration Statement only if the Holder sends by first-class registered mail or by courier with delivery confirmation, a properly completed Notice and Questionnaire to the Company. In order to be included in the Shelf
Registration Statement at the time of its effectiveness, the Notice and Questionnaire must be sent on or prior to the 20th Business Day after the date the Notice and Questionnaire is deemed to have been given in accordance with Section 7(c) hereof (or, in the case of a Holder that is a transferee of Transfer Restricted Securities, on or prior to the
earlier of (x) the 20th Business Day after the completion of the transfer of Transfer Restricted Securities to the
transferee and (y) 9:00 a.m., New York time, on the fifth Business Day prior to initial effectiveness of the Shelf Registration Statement) (in any case, the “Questionnaire Deadline”). The Company agrees and undertakes that it shall
distribute a Notice and Questionnaire (A) no later than 30 Business Days prior to the expected effectiveness of the Shelf Registration Statement to each Holder in accordance with Section 7(c) hereof, and (B) in the case of a Holder that is a
transferee of Transfer Restricted Securities, upon the request of such transferee Holder given in accordance with Section 7(c) hereof, to such Holder at the address set forth in such request. 
  
 (ii) Following the effectiveness of the Shelf Registration
Statement, upon receipt of a completed Notice and Questionnaire from a Holder, the Company will, as promptly as practicable, but in any event within 10 Business Days after its receipt thereof, file any amendments to the Shelf Registration Statement
or supplements to the related Prospectus as are necessary to permit the Holder to deliver the Prospectus to purchasers of Transfer Restricted Securities (subject to the right of the Company to suspend the use of the Prospectus as described in
Section 2(d) hereof), provided, however, that (i) if a supplement to the related Prospectus is required to permit the Holder (or other Holders not included in the Shelf Registration Statement 

  

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upon effectiveness) to deliver the Prospectus to purchasers of Transfer Restricted Securities, the Company shall not be required to file more than one (1)
such supplement during any twenty (20) day period and (ii) if a post effective amendment to the Shelf Registration Statement is required to permit the Holder (or other Holders not included in the Shelf Registration Statement upon effectiveness) to
deliver the Prospectus to purchasers of Transfer Restricted Securities, the Company shall not be required to file more than one (1) post-effective amendment to the Shelf Registration Statement in any sixty (60) day period. The Company shall use its
reasonable best efforts to cause any such post-effective amendment to become effective under the Securities Act as promptly as is practicable; provided, that if a Notice and Questionnaire is delivered to the Company during a Suspension
Period, the Company shall not be obligated to amend the Shelf Registration Statement or supplement the Prospectus until the termination of such Suspension Period. 
  
 (iii) Each Holder as to which the Shelf Registration Statement is being effected agrees to furnish promptly
to the Company (x) such other information as the Company may reasonably request for use in connection with the Shelf Registration Statement or Prospectus or in any application to be filed with or under state securities laws and (y) all information
required to be disclosed in order to make the information previously furnished to the Company by such Holder not misleading. 
  
 (c) The Company shall use its reasonable best efforts to keep the Shelf Registration Statement continuously effective, supplemented and amended under the
Securities Act in order to permit the Prospectus forming a part thereof to be usable, subject to Section 2(d) hereof, by all Notice Holders until the earliest to occur of: (i) the last date on which in the opinion of counsel to the Company the
holding period applicable to sales of all Transfer Restricted Securities under Rule 144(k) has expired; (ii) the date as of which all Transfer Restricted Securities have been transferred under Rule 144; (iii) such date as of which all Transfer
Restricted Securities have been sold pursuant to the Shelf Registration Statement; and (iv) the date that is two (2) years after the later of the Closing Date or the latest Option Closing Date (as defined in the Purchase Agreement) (in any such
case, such period being called the “Shelf Registration Period”). The Company will, in order to fulfill its obligations and this Section 2(c): (x) subject to Section 2(d), prepare and file with the SEC such amendments and
post-effective amendments to the Shelf Registration Statement as may be necessary to keep the Shelf Registration Statement continuously effective for the Shelf Registration Period; (y) subject to Section 2(d), cause the related Prospectus to be
supplemented by any required supplement, and as so supplemented to be filed pursuant to Rule 424 (or any similar provisions then in force) under the Securities Act; and (z) comply in all material respects with the provisions of the Securities Act
with respect to the disposition of all Transfer Restricted Securities covered by the Shelf Registration Statement during the Shelf Registration Period. 
  
 (d) The Company may suspend the availability of any Shelf Registration Statement and the use of any Prospectus (the period during which the availability
of any Shelf Registration Statement and any Prospectus may be suspended herein referred to as the “Suspension Period”), without incurring any obligation to pay Liquidated Damages pursuant to Section 2(e), for a period not to exceed:
(i) 45 consecutive days at any one time; (ii) 45 days in the aggregate in any three-month period; or (iii) 120 days in the aggregate during any 12-month period, in each case only for valid business reasons, to be determined in good faith by the
Company in its sole 

  

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judgment (which shall not include the avoidance of the Company’s obligations hereunder), including, without limitation, the acquisition or divestiture
of assets, pending corporate developments, public filings with the SEC and similar events; provided that if the suspension of the Shelf Registration Statement relates to a previously undisclosed proposed or pending material business
transaction, the disclosure of which, in the sole judgment of the Company, would impede the Company’s ability to consummate such transaction, the Company may extend the Suspension Period set forth in (i) and (ii) above to 75 days;
provided further, that the Company promptly thereafter complies with the requirements of Section 3(j) hereof, if applicable. 
  
 (e) The Company and the Initial Purchaser agree that the Holders of Transfer Restricted Securities will suffer damages, and it would not be feasible to
ascertain the extent of such damages with precision, if the Company fails to fulfill its obligations under Section 2 hereof. Accordingly, if: (i) the Shelf Registration Statement is not filed with the SEC on or within 90 days after the Closing Date;
(ii) the Shelf Registration Statement has not been declared effective by the SEC within 210 days after the Closing Date; or (iii) the Shelf Registration Statement is filed and declared effective but shall thereafter cease to be effective (without
being succeeded immediately by a replacement Shelf Registration Statement filed and declared effective) or usable (including as a result of a Suspension Period) for the offer and sale of Transfer Restricted Securities for a period of time (including
any Suspension Period) which exceeds: (x) 45 consecutive days at any time; (y) 45 days in the aggregate in any three-month period; or (z) 120 days in the aggregate in any 12-month period (each such event referred to in clauses (i) through (iii), a
“Registration Default”), provided that any suspension of the Shelf Registration Statement as a result of the time required by the SEC to declare effective a post-effective amendment to the Shelf Registration Statement in
connection with the Company’s obligation to file such an amendment pursuant to Section 2(d)(ii) hereof shall not be included in the calculation of a Registration Default; the Company shall pay to each Notice Holder (who is also a Record Holder)
during any period in which a Registration Default has occurred or is continuing in an amount (the “Liquidated Damages”) equal to: (i) one-quarter of one percent (25 basis points) per annum per $1,000 principal amount of Securities
constituting Transfer Restricted Securities for the period up to and including the 90th day during which such Registration Default has occurred and is continuing; and (ii) one-half of one percent (50 basis points) per annum per $1,000 principal
amount of Securities constituting Transfer Restricted Securities for the period including and subsequent to the 91st day during which such Registration Default has occurred and is continuing, it being understood that all calculations pursuant to
this and the preceding sentence shall be carried out to five decimal places. Following the cure of all Registration Defaults, Liquidated Damages will cease to accrue with respect to such Registration Defaults. All accrued Liquidated Damages shall be
paid by the Company on each Liquidated Damages Payment Date in cash to the date of such cure and Liquidated Damages will be calculated on the basis of a 360-day year consisting of twelve 30-day months. The parties hereto agree that the Liquidated
Damages provided for in this Section 2(e) constitute a reasonable estimate of the damages that may be incurred by Holders by reason of a Registration Default and that such Liquidated Damages are the only monetary damages available to Holders in the
event of a Registration Default. Notwithstanding anything in the Agreement to the contrary, Liquidated Damages shall only be payable to Notice Holders. 
  
 (f) All of the Company’s obligations (including, without limitation, the obligation to pay Liquidated Damages) set forth in the preceding paragraph
which are outstanding or exist 

  

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with respect to any Transfer Restricted Security at the time such security ceases to be a Transfer Restricted Security shall survive until such time as all
such obligations with respect to such security shall have been satisfied in full. Notwithstanding the foregoing, no Liquidated Damages shall accrue as to any Transfer Restricted Security from and after the earlier of: (i) the date such security is
no longer a Transfer Restricted Security; and (ii) the expiration of the Shelf Registration Period. 
  
 (g) Immediately upon the occurrence or the termination of a Registration Default, the Company shall give the Trustee, so long as the Securities remain
outstanding, notice of such commencement or termination of the obligation to pay Liquidated Damages with regard to the Securities, and the amount thereof and of the nature of the default giving rise to such commencement or the event giving rise to
such termination, as the case may be (such notice to be contained in an Officer’s Certificate (as such term is defined in the Indenture)), and prior to receipt of such Officer’s Certificate the Trustee and the transfer and paying agent
shall be entitled to assume that no such commencement or termination has occurred, as the case may be. 
  
 3. Registration Procedures. In connection with any Shelf Registration Statement, the following provisions shall apply: 
  
 (a) The Company shall: (i) furnish to the Initial Purchaser, within a reasonable period of time, but in any event within three Business Days, prior to the
filing thereof with the SEC to afford the Initial Purchaser and its counsel a reasonable opportunity for review, a copy of each Shelf Registration Statement, and each amendment thereof, and a copy of each Prospectus, and each amendment or supplement
thereto (excluding amendments caused by the filing of a report under the Exchange Act), and shall reflect in each such document, when so filed with the SEC, such comments as the Initial Purchaser may reasonably propose, except to the extent the
Company reasonably determines it to be inadvisable or inappropriate to reflect such comments therein; and (ii) include information regarding the Notice Holders and the methods of distribution they have elected for their Transfer Restricted
Securities provided to the Company in Notice and Questionnaires as necessary to permit such distribution by the methods specified therein. 
  
 (b) Subject to Section 2(d), the Company shall ensure that: (i) any Shelf Registration Statement and any amendment thereto and any Prospectus forming a
part thereof and any amendment or supplement thereto comply in all material respects with the Securities Act and the rules and regulations thereunder; (ii) any Shelf Registration Statement and any amendment thereto does not, when it becomes
effective, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; and (iii) any Prospectus forming a part of any Shelf Registration
Statement, and any amendment or supplement to such Prospectus, does not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in light of the circumstances under which they
were made, not misleading; provided that the Company makes no representation with respect to any Holder Information. 
  

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 (c) The Company, as promptly as reasonably practicable (but in any event within two Business Days), shall
notify the Initial Purchaser and each Notice Holder: 
  
 (i) when any Prospectus or any supplement thereto has been filed with the SEC and when the Shelf Registration Statement or any post-effective amendment thereto has become effective; 
  
 (ii) of the issuance by the SEC or any other federal or
state governmental authority of any stop order suspending the effectiveness of the Shelf Registration Statement or of any order preventing or suspending the use of any Prospectus or the initiation or threat of any proceedings for that purpose;

  
 (iii) of the receipt by the Company of any
notification with respect to the suspension of the qualification or exemption from qualification of the Transfer Restricted Securities included in any Shelf Registration Statement for sale in any jurisdiction or the initiation or threat of any
proceeding for that purpose; 
  
 (iv) of the
occurrence of, but not the nature of or details concerning, any event or the existence of any condition that requires the making of any changes in the Shelf Registration Statement or the Prospectus or any document incorporated by reference therein
so that, as of such date, the statements therein are not misleading and the Shelf Registration Statement or the Prospectus or any document incorporated by reference therein, as the case may be, does not include an untrue statement of a material fact
or omit to state a material fact required to be stated therein or necessary to make the statements therein (in the case of the Prospectus, in light of the circumstances under which they were made) not misleading; 
  
 (v) of the Company’s determination that a
post-effective amendment to the Shelf Registration Statement is necessary (other than a post-effective amendment pursuant to Section 2(b)(ii)); and 
  
 (vi) of the commencement (including as a result of any of the events or circumstances described in paragraph (ii) above) and termination
of any Suspension Period. 
  
 (d) The Company shall use its
reasonable best efforts to obtain: (i) the withdrawal of any order suspending the effectiveness of any Shelf Registration Statement and the use of any related Prospectus; and (ii) the lifting of any suspension of the qualification (or exemption from
qualification) of any of the Transfer Restricted Securities for offer or sale in any jurisdiction in which they have been qualified for sale, in each case at the earliest possible time, and shall provide notice to each Notice Holder and the Initial
Purchaser of the withdrawal of any such orders or suspensions. 
  
 (e) The Company shall promptly furnish to the Initial Purchaser (and, upon written request from any Notice Holder to such Notice Holder), without charge, at least one copy of any Shelf Registration Statement and any post-effective amendment
thereto, excluding all documents incorporated or deemed to be incorporated therein by reference and all exhibits thereto. 
  
 (f) The Company shall, during the Shelf Registration Period, promptly deliver to the Initial Purchaser and each Notice Holder, without charge, as many
copies of the Prospectus (including each preliminary Prospectus) included in any Shelf Registration Statement, and any amendment or supplement thereto, as such person may reasonably request and except as provided in Sections 2(d) and 3(p) hereof;
and the Company hereby consents to the use of the 

  

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Prospectus and any amendment or supplement thereto by each of the selling Holders in connection with the offering and sale of the Transfer Restricted
Securities covered by the Prospectus or any amendment or supplement thereto. 
  
 (g) Prior to any offering of Transfer Restricted Securities pursuant to any Shelf Registration Statement, the Company shall register or qualify or cooperate with the Notice Holders and their respective counsel in
connection with the registration or qualification (or exemption from such registration or qualification) of such Transfer Restricted Securities for offer and sale, under the securities or blue sky laws of such jurisdictions within the United States
as any such Notice Holders reasonably request and shall maintain such qualification in effect so long as required and do any and all other acts or things necessary or advisable to enable the offer and sale in such jurisdictions of the Transfer
Restricted Securities covered by such Shelf Registration Statement; provided, however, that the Company will not be required to: (i) qualify generally to do business as a foreign corporation or as a dealer in securities in any
jurisdiction where it is not then so qualified or; (ii) take any action which would subject it to service of process or taxation in excess of a nominal dollar amount in any such jurisdiction where it is not then so subject. 
  
 (h) If the Transfer Restricted Securities are in certificated form, the
Company shall cooperate with the Holders to facilitate the timely preparation and delivery of certificates representing Transfer Restricted Securities sold pursuant to any Shelf Registration Statement free of any restrictive legends and, with
respect of any Securities, in such denominations permitted by the Indenture and registered in such names as Holders may request at least two Business Days prior to settlement of sales of Transfer Restricted Securities pursuant to such Shelf
Registration Statement. 
  
 (i) Subject to the exceptions
contained in (i) and (ii) of Section 3(g) above, the Company shall use its reasonable best efforts to cause the Transfer Restricted Securities covered by the applicable Shelf Registration Statement to be registered with or approved by such other
federal, state and local governmental agencies or authorities, and self-regulatory organizations in the United States as may be necessary to enable the Holders to consummate the disposition of such Transfer Restricted Securities as contemplated by
the Shelf Registration Statement; without limitation to the foregoing, the Company shall provide all such information as may be required by the NASD in connection with the offering under the Shelf Registration Statement of the Transfer Restricted
Securities (including, without limitation, such as may be required by NASD Rule 2710 or 2720), and shall cooperate with each Holder in connection with any filings required to be made with the NASD by such Holder in that regard. 
  
 (j) Upon the occurrence of any event described in Section 3(c)(iv) or 3(c)(v)
hereof, the Company shall promptly prepare and file with the SEC a post-effective amendment to any Shelf Registration Statement, or an amendment or supplement to the related Prospectus, or any document incorporated therein by reference, or file a
document which is incorporated or deemed to be incorporated by reference in such Shelf Registration Statement or Prospectus, as the case may be, so that, as thereafter delivered to purchasers of the Transfer Restricted Securities included therein,
the Shelf Registration Statement and the Prospectus, in each case as then amended or supplemented, will not include an untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make
the statements 

  

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therein (in the case of the Prospectus, in light of the circumstances under which they were made) not misleading and, in the case of a post-effective
amendment, use its reasonable best efforts to cause it to become effective as promptly as practicable; provided that the Company’s obligations under this paragraph (j) shall be suspended if the Company has suspended the use of the
Prospectus in accordance with Section 2(d) hereof and given notice of such suspension to Notice Holders, it being understood that the Company’s obligations under this Section 3(j) shall be automatically reinstated at the end of such Suspension
Period. 
  
 (k) The Company shall provide, prior to the effective
date of any Shelf Registration Statement hereunder a CUSIP number for the Transfer Restricted Securities registered under such Shelf Registration Statement. 
  
 (l) The Company shall use its reasonable best efforts to comply with all applicable rules and regulations of the SEC and shall make generally available to
its security holders an earnings statement satisfying the provisions of Section 11(a) of the Securities Act and Rule 158 promulgated by the SEC thereunder (or any similar rule promulgated under the Securities Act) for a 12-month period commencing on
the first day of the first fiscal quarter of the Company commencing after the effective date of any Shelf Registration Statement or each post-effective amendment to any Shelf Registration Statement, which such statements shall be made available no
later than 45 days after the end of the 12-month period or 90 days after the end of the 12-month period, if the 12-month period coincides with the fiscal year of the Company. 
  
 (m) The Company shall use its reasonable best efforts to cause the Indenture to be qualified under the TIA (as defined in
the Indenture) not later than the effective date of the first Shelf Registration Statement. 
  
 (n) The Company shall cause all shares of Common Stock issuable upon conversion of the Securities to be reserved for listing on each securities exchange or quotation system on which the Common Stock is then listed no
later than the date the applicable Shelf Registration Statement is declared effective and, shall cause all Common Stock to be so listed when issued, and, in connection therewith, to make such filings as may be required under the Exchange Act and to
have such filings declared effective as and when required thereunder. 
  
 (o) If reasonably requested in writing in connection with any disposition of Transfer Restricted Securities pursuant to a Shelf Registration Statement, make reasonably available for inspection during normal business hours by a
representative for the Notice Holders of such Transfer Restricted Securities and any broker-dealers, attorneys and accountants retained by such Notice Holders, all relevant financial and other records, pertinent corporate documents and properties of
the Company and its subsidiaries, and cause the appropriate executive officers, directors and designated employees of the Company and its subsidiaries to make reasonably available for inspection during normal business hours all relevant information
reasonably requested by such representative for the Notice Holders or any such broker-dealers, attorneys or accountants in connection with such disposition, in each case as is customary for similar “due diligence” examinations;
provided, however, that any information that is designated by the Company, in good faith, as confidential at the time of delivery of such information shall be kept confidential by such persons, unless disclosure thereof is made in
connection with a court, administrative or regulatory proceeding or required by law, or such information has become 

  

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available to the public generally through the Company or through a third party without an accompanying obligation of confidentiality. 
  
 (p) Each Notice Holder agrees that, upon receipt of notice of the happening
of an event described in Sections 3(c)(ii) through and including 3(c)(vi), it shall forthwith discontinue (and shall cause its agents and representatives to discontinue) disposition of Transfer Restricted Securities and will not resume disposition
of Transfer Restricted Securities until such Holder has received copies of an amended or supplemented Prospectus contemplated by Section 3(j) hereof, or until such Notice Holder is advised in writing by the Company that the use of the Prospectus may
be resumed or that the relevant Suspension Period has been terminated, as the case may be, provided that the foregoing shall not prevent the sale, transfer or other disposition of Transfer Restricted Securities by a Holder in a transaction
which is exempt from, or not subject to, the registration requirements of the Securities Act, so long as such Holder does not and is not required to deliver the applicable Prospectus or Shelf Registration Statement in connection with such sale,
transfer or other disposition, as the case may be; and provided, further, that the provisions of this Section 3(p) shall not prevent the occurrence of a Registration Default or otherwise limit the obligation of the Company to pay
Liquidated Damages. 
  
 (q) The Company shall use its reasonable
best efforts to take all other steps necessary to effect the registration of the Securities covered by the Shelf Registration Statement contemplated hereby. 
  
 4. Registration Expenses. The Company shall bear all fees and expenses incurred in connection with the performance of its obligations under Sections 2 and 3 hereof
and shall reimburse the Holders for the reasonable fees and disbursements of one firm or counsel designated by the Company (and reasonably acceptable to the Initial Purchaser acting on behalf of the Holders) to act as counsel for the Holders in
connection therewith. Such fees and expenses shall include, without limitation: (i) all registration and filing fees and expenses (including filings made with the NASD); (ii) all fees and expenses of compliance with federal securities and state Blue
Sky or securities laws; (iii) all expenses of printing (including printing of Prospectuses and certificates for the Common Stock to be issued upon conversion of the Securities) and the Company’s expenses for messenger and delivery services and
telephone; (iv) all fees and disbursements of counsel to the Company; (v) all application and filing fees in connection with listing (or authorizing for quotation) the Common Stock on a national securities exchange or automated quotation system
pursuant to the requirements hereof; and (vi) all fees and disbursements of independent certified public accountants of the Company. The Company shall bear its internal expenses (including, without limitation, all salaries and expenses of their
officers and employees performing legal, accounting or other duties), the expenses of any annual audit and the fees and expenses of any Person, including special experts, retained by the Company. Notwithstanding the provisions of this Section 4,
each Holder shall bear the expense of any broker’s commission, agency fee and underwriter’s discount or commission (including, without limitation, the expenses related to the engagement of a “qualified independent underwriter”),
if any, relating to the sale or disposition of such Holder’s Transfer Restricted Securities pursuant to a Shelf Registration Statement. 
  

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 5. Indemnification and Contribution. 
  
 (a) The Company agrees to indemnify and hold harmless each Holder of Transfer Restricted Securities covered by any Shelf
Registration Statement (including, without limitation, each Initial Purchaser), its directors, officers, and employees and each person, if any, who controls any such Holder within the meaning of either the Securities Act or the Exchange Act
(collectively referred to for purposes of this Section 5 as a “Holder”) against any losses, claims, damages or liabilities, joint or several, or actions in respect thereof, to which any of them may become subject, under the
Securities Act or otherwise, insofar as such losses, claims, damages, liabilities or actions arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Shelf Registration Statement, or in any
Prospectus, or any amendment thereof or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact necessary to make the statements therein, in the light of the circumstances under which
they were made, not misleading, and will reimburse each such party for any legal or other expenses reasonably incurred by such party in connection with investigating or defending any such action or claim as such expenses are incurred;
provided, however, that: (i) the Company shall not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon Holder Information; and (ii) with respect to any untrue statement
or omission of material fact made in any Shelf Registration Statement, or in any Prospectus, the indemnity agreement contained in this Section 5(a) shall not inure to the benefit of the Holder or any person who controls the Holder within the meaning
of either the Securities Act or the Exchange Act from whom the person asserting any such loss, claim, damage or liability purchased the securities concerned, to the extent that any such loss, claim, damage or liability of the Holders occurs under
the circumstance where it shall have been established that: (w) the Company had previously furnished copies of the Prospectus, and any amendments and supplements thereto, to the Holder; (x) delivery of the Prospectus, and any amendment or
supplements thereto, was required by the Securities Act to be made to such person; (y) the untrue statement or omission of a material fact contained in the Prospectus was corrected in amendments or supplements thereto; and (z) there was not sent or
given to such person, at or prior to the written confirmation of the sale of such securities to such person, a copy of such amendments or supplements to the Prospectus. This indemnity agreement will be in addition to any liability that the Company
may otherwise have. This indemnity agreement will not apply to any loss, damage, expense, liability or claim arising from an offer or sale, occurring during a Suspension Period, of Transfer Restricted Securities by a Notice Holder who has previously
received notice from the Company of the commencement of the Suspension Period pursuant to Section 3(c)(vi). 
  
 (b) Each Holder, severally and not jointly, agrees to indemnify and hold harmless the Company, each of its directors and officers and each person, if any,
who controls the Company within the meaning of either the Securities Act or the Exchange Act, to the same extent as the foregoing indemnity from the Company to the Holders and agrees to reimburse each such indemnified party, as incurred, for any
legal or other expenses reasonably incurred by them in connection with investigating or defending any loss, claim, damage, liability or action, but only with reference to Holder Information supplied by such Holder. In no event shall any Holder, its
directors, officers or any person, if any, who controls such Holder be liable or responsible for any amount in excess of the amount by which the total amount received by such Holder with respect to its sale of Transfer Restricted Securities pursuant
to a Shelf Registration Statement 

  

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exceeds: (i) the amount paid by such Holder for such Transfer Restricted Securities; plus (ii) the amount of any damages that such Holder, its directors,
officers or any person who controls such Holder has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. This indemnity agreement will be in addition to any liability that such Holder
may otherwise have. 
  
 (c) Promptly after receipt by an
indemnified party under this Section 5 of notice of any claim or the commencement of any action or proceeding (including any governmental investigation), such indemnified party will, if a claim for indemnification in respect thereof is to be made
against the indemnifying party under Section 5(a) or 5(b) hereof, notify the indemnifying party in writing of the commencement thereof; but the omission so to notify the indemnifying party will not relieve it from any liability which it may have to
any indemnified party to the extent it is not materially prejudiced as a result thereof and in any event shall not relieve it from any liability which it may have otherwise than on account of this indemnity agreement. In case any such action or
proceeding is brought against any indemnified party, and it notifies the indemnifying party of the commencement thereof, the indemnifying party will be entitled to participate therein (jointly with any other indemnifying party similarly notified),
and to the extent that it may elect, by written notice, delivered to such indemnified party promptly after receiving the aforesaid notice from such indemnified party, to assume the defense thereof, with counsel reasonably satisfactory to such
indemnified party; provided, however, that if the defendants (including any impleaded parties) in any such action include both the indemnified party and the indemnifying party and the indemnified party shall have reasonably concluded
that there may be legal defenses available to it and/or other indemnified parties which are different from or additional to those available to the indemnifying party, the indemnified party or parties shall have the right to select separate counsel
to defend such action on behalf of such indemnified party or parties. Upon receipt of notice from the indemnifying party to such indemnified party of its election so to appoint counsel to defend such action and approval by the indemnified party of
such counsel, the indemnifying party will not be liable to such indemnified party under this Section 5 for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof unless: (i) the indemnified
party shall have employed separate counsel in accordance with the proviso to the preceding sentence (it being understood, however, that the indemnifying party shall not be liable for the expense of more than one separate counsel (in addition to any
local counsel), approved by the Holders in the case of paragraph (a) of this Section 5, representing the indemnified parties under such paragraph (a) who are parties to such action); (ii) the indemnifying party shall not have employed counsel
reasonably satisfactory to the indemnified party to represent the indemnified party within a reasonable time after notice or commencement of the action; (iii) the indemnifying party has authorized the employment of counsel for the indemnified party
at the expense of the indemnifying party; or (iv) the use of counsel chosen by the indemnifying party to represent the indemnified party would present such counsel with a conflict of interest. An indemnifying party will not, without the prior
written consent of the indemnified parties, settle or compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought
hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless such settlement, compromise or consent includes an unconditional release of each indemnified party from all liability arising out of
such claim, action, suit or proceeding. Subject to the provisions of the immediately following sentence, no indemnifying party shall be liable for 

  

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any settlement, compromise or the consent to the entry of judgment in connection with any such action effected without its written consent, but if settled
with its written consent or if there be a final judgment for the plaintiff in any such action other than a judgment entered with the consent of such indemnified party, the indemnifying party agrees to indemnify and hold harmless any indemnified
party from and against any loss or liability by reason of such settlement or judgment. If at any time an indemnified party shall have requested that an indemnifying party reimburse the indemnified party for reasonable fees and expenses of counsel as
contemplated by this Section 5(c) and to which it would be entitled under Section 5(a) or 5(b) hereof, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if: (x) such
settlement is entered into more than 45 days after receipt by such indemnifying party of such request for reimbursement, (y) such indemnifying party shall have received notice of the terms of such settlement at least 30 days prior to such settlement
being entered into and (z) such indemnifying party shall not have reimbursed such indemnified party in accordance with such request prior to the date of such settlement. 
  
 (d) In the event that the indemnity provided in paragraph (a) or (b) of this Section 5 is unavailable to or insufficient to
hold harmless an indemnified party for any reason, each indemnifying party agrees to contribute to the aggregate losses, claims, damages and liabilities (including legal or other expenses reasonably incurred in connection with investigating or
defending same) (collectively, “Losses”) to which the indemnified party may be subject in such proportion as is appropriate to reflect the relative benefits received by the Company from the Initial Placement, on the one hand, and a
Holder with respect to the sale by such Holder of Securities or Common Stock, on the other hand; provided, however, that in no case shall an indemnifying party that is a Holder be responsible for any amount in excess of the total price
at which the Transfer Restricted Securities are sold by such Holder to a purchaser. If the allocation provided by the immediately preceding sentence is unavailable for any reason, the Company and such Holder shall contribute in such proportion as is
appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and of such Holder on the other in connection with the statements or omissions which resulted in such Losses, as well as any other
relevant equitable considerations. The relative benefits received by the Company on the one hand and such Holder on the other shall be deemed to be in the same respective proportions as the total net proceeds from the Initial Placement (before
deducting expenses) received by or on behalf of the Company as set forth in the Offering Memorandum, on the one hand, and the total proceeds received by such Holder with respect to its sale of Transfer Restricted Securities under the Shelf
Registration Statement, on the other hand, bear to the total gross proceeds from the Initial Placement. Relative fault shall be determined by reference to, among other things, whether any untrue or any alleged untrue statement of a material fact or
the omission or alleged omission to state a material fact relates to information provided by the Company on the one hand or relates to Holder Information supplied by such Holder, on the other, the intent of the parties and their relative knowledge,
information and opportunity to correct or prevent such untrue statement or omission. The parties agree that it would not be just and equitable if contribution pursuant to this paragraph (d) were determined by pro rata allocation or any other method
of allocation that does not take account of the equitable considerations referred to above. Notwithstanding the provisions of this paragraph (d), no person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities
Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 5(d), each person who controls such Holder 

  

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within the meaning of either the Securities Act or the Exchange Act shall have the same rights to contribution as such Holder, and each person who controls
the Company within the meaning of either the Securities Act or the Exchange Act and each officer and director of the Company shall have the same rights to contribution as the Company, subject in each case to the applicable terms and conditions of
this paragraph (d). 
  
 (e) The provisions of this Section 5 will
remain in full force and effect, regardless of any investigation made by or on behalf of any Holder, any underwriter or the Company or any of the officers, directors or controlling persons referred to in Section 5 hereof, and will survive the sale
by a Holder of Transfer Restricted Securities covered by a Shelf Registration Statement. 
  
 6. Rules 144 and 144A. The Company covenants that it shall use its reasonable best efforts to file the reports required to be filed by it under the Securities Act and the Exchange Act in a timely manner so long
as the Transfer Restricted Securities remain outstanding. If at any time the Company is not required to file such reports, it will, upon request of any Holder or beneficial owner of Transfer Restricted Securities, make available such information
necessary to permit sales pursuant to Rule 144A. The Company further covenants that, for as long as any Transfer Restricted Securities remain outstanding, it will take such further action as any Holder of Transfer Restricted Securities may
reasonably request, all to the extent required from time to time to enable such Holder to sell Transfer Restricted Securities without registration under the Securities Act within the limitation of the exemptions provided by Rule 144 and Rule 144A.
Upon the written request of any Holder of Transfer Restricted Securities, the Company shall deliver to such Holder a written statement as to whether it has complied with such requirements. 
  

	7.	Miscellaneous. 

  
 (a) No Inconsistent Agreements. The Company has not, as of the date hereof, entered into nor shall it, on or after the date hereof, enter into, any
agreement with respect to its securities that is inconsistent with the rights granted to the Holders herein or otherwise conflicts with the provisions hereof. In addition, the Company shall not grant to any of its securityholders (other than the
Holders of Transfer Restricted Securities in such capacity) the right to include any of its securities in the Shelf Registration Statement provided for in this Agreement other than the Transfer Restricted Securities. 
  
 (b) Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, qualified, modified or supplemented, and waivers or consents to departures from the provisions hereof may not be given, unless the Company consents in writing and the Company has
obtained the written consent of at least the majority of the Holders of the then outstanding Transfer Restricted Securities; provided that with respect to any matter that directly or indirectly affects the rights of the Initial Purchaser
hereunder, the Company shall obtain the written consent of the Initial Purchaser against which such amendment, qualification, supplement, waiver or consent is to be effective. Notwithstanding the foregoing (except the foregoing proviso), a waiver or
consent to departure from the provisions hereof with respect to a matter that relates exclusively to the rights of Holders whose Transfer Restricted Securities are being sold pursuant to a Shelf Registration Statement and that does not directly or
indirectly affect the rights of other Holders may be given by the Majority Holders. 
  

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 (c) Notices. All notices and other communications provided for or permitted hereunder shall be
made in writing by hand-delivery, first-class mail, telecopier, or air courier guaranteeing overnight delivery: 
  
 (i) if to the Initial Purchaser, initially at its address set forth in the Purchase Agreement; 
  
 (ii) if to any other Holder, at the most current address of
such Holder maintained by the Registrar under the Indenture or the registrar of the Common Stock (provided that while the Securities or the Common Stock are in book-entry form, notice to the Trustee shall serve as notice to the Holders), or,
in the case of the Notice Holder, the address set forth in its Notice and Questionnaire; and 
  
 (iii) if to the Company, to: 
  
 Oscient Pharmaceuticals Corporation 
 100
Beaver Street 
 Waltham, MA 02453 
 Facsimile: (781) 893-9535 
 Attn: Chief Financial Officer 
  
 With a copy to: 
  
 Ropes & Gray LLP 
 One International
Place 
 Boston, MA 02110-2624 
 Facsimile: (617) 951-7050 
 Attn: Patrick O’Brien, Esq. 
  
 All such notices and communications shall be deemed to have been duly given when received, if delivered by hand or air courier, and when
sent, if sent by first-class mail or telecopier. 
  
 The Initial
Purchaser or the Company by notice to the other may designate additional or different addresses for subsequent notices or communications. 
  
 (d) Successors and Assigns. This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties,
including, without the need for an express assignment or any consent by the Company thereto, subsequent Holders. The Company hereby agrees to extend the benefits of this Agreement to any Holder and underwriter and any such Holder and underwriter may
specifically enforce the provisions of this Agreement as if an original party hereto. In the event that any other person shall succeed to the Company under the Indenture, then such successor shall enter into an agreement, in form and substance
reasonably satisfactory to the Initial Purchaser, whereby such successor shall assume all of the Company’s obligations under this Agreement. 
  
 (e) Counterparts. This Agreement may be executed in any number of counterparts and by the parties hereto in separate counterparts, each of which
when so executed shall be 

  

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deemed to be an original and all of which taken together shall constitute one and the same agreement. 
  
 (f) Headings. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof. 
  
 (g) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS MADE AND TO BE PERFORMED IN SAID STATE. 
  
 (h) Severability. In the event that any one of more of the provisions
contained herein, or the application thereof in any circumstances, is held invalid, illegal or unenforceable in any respect for any reason, the validity, legality and enforceability of any such provision in every other respect and of the remaining
provisions hereof shall not be in any way impaired or affected thereby, it being intended that all of the rights and privileges of the parties shall be enforceable to the fullest extent permitted by law. 
  
 (i) Securities Held by the Company, Etc. Whenever the consent or
approval of Holders of a specified percentage of principal amount of Securities or the shares of Common Stock issuable upon conversion thereof is required hereunder, Securities or the shares of Common Stock issued upon conversion thereof held by the
Company or its Affiliates (other than subsequent Holders of Securities or the Common Stock issued upon conversion thereof if such subsequent Holders are deemed to be Affiliates solely by reason of their holdings of such Securities) shall not be
counted in determining whether such consent or approval was given by the Holders of such required percentage. 
  
 (j) Termination. This Agreement and the obligations of the parties hereunder shall terminate upon the end of the Shelf Registration Period, except
for any liabilities or obligations under Section 2(e), 4 or 5 to the extent arising prior to the end of the Shelf Registration Period. 
  

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 Please confirm that the foregoing correctly sets forth the agreement between the Company and you.

  
 Very truly yours, 
  

			
	OSCIENT PHARMACEUTICALS CORPORATION
		
	By:	 	/s/    STEPHEN COHEN
	 Name:
	 	Stephen Cohen
	 Title:
	 	Senior Vice President and CFO

  
 The foregoing Agreement is hereby
confirmed and accepted as of the date first above written. 
  

			
	SMITHFIELD FIDUCIARY LLC
		
	By:	 	/s/    ADAM J. CHILL
	 Name:
	 	Adam J. Chill
	 Title:
	 	Authorized Signatory

  

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