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  <p style="border:none;margin:0in 0in .0001pt;padding:0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
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  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">SECURITIES AND EXCHANGE COMMISSION</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">WASHINGTON, DC 20549</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <div align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><hr size="1" width="25%" noshade color="black" align="center"></div>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">FORM&nbsp;8-K</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">CURRENT
  REPORT<br>
  PURSUANT TO SECTION&nbsp;13 OR 15(D)&nbsp;OF THE<br>
  SECURITIES EXCHANGE ACT OF 1934</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="font-size:10.0pt;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman"><font style="font-size:10.0pt;">Date of Report (Date of earliest event reported): <b>April&nbsp;</b></font><b>23</b></font><b>,
  2008</b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">CUBIST PHARMACEUTICALS, INC.</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Exact Name of Registrant as Specified in Charter)</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
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    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Delaware</font></b></p>
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    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">0-21379</font></b></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">22-3192085</font></b></p>
    </td>
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    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(State or Other Jurisdiction</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Commission</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(IRS Employer</font></p>
    </td>
   </tr>
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    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">of Incorporation)</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">File Number)</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Identification No.)</font></p>
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  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">65 Hayden Avenue, Lexington, Massachusetts&#160; 02421</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Address of Principal Executive Offices) (Zip Code)</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Registrant&#146;s telephone number, including area code:&#160;&#160;&#160; <b>(781) 860-8660</b></font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check the appropriate box below if the Form&nbsp;8-K
  filing is intended to simultaneously satisfy the filing obligation of the
  registrant under any of the following provisions:</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" face="Times New Roman" style="font-size:10.0pt;">
  Written communications pursuant to Rule&nbsp;425 under the Securities Act (17
  CFR 230.425)</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" face="Times New Roman" style="font-size:10.0pt;">
  Soliciting material pursuant to Rule&nbsp;14a-12(b)&nbsp;under the Exchange Act
  (17 CFR 240.14a-12(b))</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" face="Times New Roman" style="font-size:10.0pt;">
  Pre-commencement communications pursuant to Rule&nbsp;14d-2(b)&nbsp;under the
  Exchange Act (17 CFR 240.14d-2(b))</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font><font size="2" face="Times New Roman" style="font-size:10.0pt;">
  Pre-commencement communications pursuant to Rule&nbsp;13e-4(c)&nbsp;under the
  Exchange Act (17 CFR 240.13e-4(c))</font></p>
  
  <div style="border:none;border-bottom:double windowtext 6.0pt;padding:0in 0in 0in 0in;">
  
  <p style="border:none;margin:0in 0in .0001pt;padding:0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  </div>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <div style="margin:0in 0in .0001pt;text-autospace:none;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
  
  </div>
  <!-- SEQ.=1,FOLIO='',FILE='C:\jms\sethu\08-12839-1\task2901254\12839-1-ba.htm',USER='105167',CD='Apr 29 13:00 2008' -->
  
  
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  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 1.01&#160;
  Entry Into a Material Definitive Agreement.</font></b></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">On April&nbsp;23,
  2008, the registrant, Cubist Pharmaceuticals,&nbsp;Inc., a Delaware corporation
  (&#147;Cubist&#148;), and Dyax Corp., a Delaware corporation (&#147;Dyax&#148;), entered into a
  License and Collaboration Agreement (the &#147;License Agreement&#148;), pursuant to
  which Cubist obtained an exclusive license for the development and
  commercialization of the intravenous formulation of DX-88 for the prevention of
  blood loss during surgery in North America and Europe.</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to
  the terms of the License Agreement, Cubist will pay to Dyax a $15 million
  upfront payment, an additional $2.5 million milestone payment in 2008 and up to
  an additional $214 million in clinical, regulatory and sales-based milestone
  payments. &#160;Cubist also is obligated to
  pay Dyax tiered, double-digit royalties based on sales of DX-88 by Cubist. &#160;The License Agreement provides an option for
  Dyax to retain certain US co-promotion rights. &#160;Cubist will be responsible for costs
  associated with the ongoing DX-88 on-pump cardiothoracic surgery Phase 2 trial,
  known as Kalahari 1, as well as all further development costs associated with
  DX-88 in the licensed indications for the Cubist territory.&#160; Dyax retains exclusive rights to DX-88 in all
  other indications, including its hereditary angioedema program, currently in
  its second Phase 3 trial, as well as for the manufacturing of DX-88.&#160; Except under certain circumstances, Dyax will
  supply Cubist with DX-88 for development and commercialization.&#160; The License Agreement may be terminated by
  Cubist without cause on prior notice to Dyax and by either party in the event
  of a breach of specified provisions of the License Agreement by the other
  party.</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The
  foregoing description of the License Agreement contained in this Item 1.01 does
  not purport to be complete and is qualified in its entirety by reference to the
  complete text of the License Agreement, which will be filed, with confidential
  terms redacted, with the SEC as an exhibit to Cubist&#146;s Quarterly Report on Form&nbsp;10-Q
  for the period ending on June&nbsp;30, 2008.</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The full
  text of a April&nbsp;24, 2008 press release announcing Cubist and Dyax entering
  into the License Agreement is attached hereto as Exhibit&nbsp;99.1.</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Item 9.01 Financial Statements and
  Exhibits.</font></b></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;">(d)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Exhibits.</font></i></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><b><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;font-weight:bold;">&nbsp;</font></i></b></p>
  
  <table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
   <tr>
    <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.34%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.4%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">99.1</font></p>
    </td>
    <td width="87%" valign="top" style="padding:0in 0in 0in 0in;width:87.26%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Press Release dated April&nbsp;24, 2008</font></p>
    </td>
   </tr>
  </table>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">SIGNATURES</font></b></p>
  
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the Securities Exchange Act
  of 1934, the registrant has duly caused this report to be signed on its behalf
  by the undersigned hereunto duly authorized.</font></p>
  
  <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
   <tr>
    <td width="44%" valign="top" style="padding:0in .7pt 0in .7pt;width:44.46%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="55%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:55.54%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">CUBIST PHARMACEUTICALS, INC.</font></p>
    </td>
   </tr>
   <tr>
    <td width="44%" valign="top" style="padding:0in .7pt 0in .7pt;width:44.46%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="6%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:6.64%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="48%" valign="top" style="padding:0in .7pt 0in .7pt;width:48.9%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="44%" valign="top" style="padding:0in .7pt 0in .7pt;width:44.46%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="6%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:6.64%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="48%" valign="top" style="padding:0in .7pt 0in .7pt;width:48.9%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="44%" valign="top" style="padding:0in .7pt 0in .7pt;width:44.46%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="3%" valign="top" style="padding:0in .7pt 0in .7pt;width:3.22%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>
    </td>
    <td width="52%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:52.32%;">
    <p style="margin:0in 0in .0001pt 30.0pt;text-autospace:none;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ David W. J. McGirr</font></p>
    </td>
   </tr>
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    <td width="44%" valign="top" style="padding:0in .7pt 0in .7pt;width:44.46%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="6%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:6.64%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="48%" valign="top" style="padding:0in .7pt 0in .7pt;width:48.9%;">
    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">David W. J. McGirr</font></p>
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    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior Vice President and</font></p>
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    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
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    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
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    <p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Chief Financial Officer</font></p>
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  <p align="left" style="margin:0in 0in .0001pt;text-align:left;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Dated: April&nbsp;29, 2008</font></p>
  
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  <p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>
  
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metadata_filer: {"company-data": {"conformed-name": "CUBIST PHARMACEUTICALS INC", "cik": "0000912183", "assigned-sic": "2834", "irs-number": "223192085", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-21379", "film-number": "08785164"}, "business-address": {"street1": "65 HAYDEN AVENUE", "city": "LEXINGTON", "state": "MA", "zip": "02421", "phone": "781-860-8660"}, "mail-address": {"street1": "24 EMILY ST", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}}
text: SECURITIES AND EXCHANGE COMMISSION
  WASHINGTON, DC 20549
  FORM 8-K
  CURRENT
  REPORT
  PURSUANT TO SECTION 13 OR 15(D) OF THE
  SECURITIES EXCHANGE ACT OF 1934
  Date of Report (Date of earliest event reported):
  April
  23
  ,
  2008
  CUBIST PHARMACEUTICALS, INC.
  (Exact Name of Registrant as Specified in Charter)
  Delaware
  0-21379
  22-3192085
  (State or Other Jurisdiction
  (Commission
  (IRS Employer
  of Incorporation)
  File Number)
  Identification No.)
  65 Hayden Avenue, Lexington, Massachusetts  02421
  (Address of Principal Executive Offices) (Zip Code)
  Registrant's telephone number, including area code:
  (781) 860-8660
  Check the appropriate box below if the Form 8-K
  filing is intended to simultaneously satisfy the filing obligation of the
  registrant under any of the following provisions:
  o
  Written communications pursuant to Rule 425 under the Securities Act (17
  CFR 230.425)
  o
  Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act
  (17 CFR 240.14a-12(b))
  o
  Pre-commencement communications pursuant to Rule 14d-2(b) under the
  Exchange Act (17 CFR 240.14d-2(b))
  o
  Pre-commencement communications pursuant to Rule 13e-4(c) under the
  Exchange Act (17 CFR 240.13e-4(c))
  Item 1.01 
  Entry Into a Material Definitive Agreement.
  On April 23,
  2008, the registrant, Cubist Pharmaceuticals, Inc., a Delaware corporation
  ("Cubist"), and Dyax Corp., a Delaware corporation ("Dyax"), entered into a
  License and Collaboration Agreement (the "License Agreement"), pursuant to
  which Cubist obtained an exclusive license for the development and
  commercialization of the intravenous formulation of DX-88 for the prevention of
  blood loss during surgery in North America and Europe.
  Pursuant to
  the terms of the License Agreement, Cubist will pay to Dyax a $15 million
  upfront payment, an additional $2.5 million milestone payment in 2008 and up to
  an additional $214 million in clinical, regulatory and sales-based milestone
  payments.  Cubist also is obligated to
  pay Dyax tiered, double-digit royalties based on sales of DX-88 by Cubist.  The License Agreement provides an option for
  Dyax to retain certain US co-promotion rights.  Cubist will be responsible for costs
  associated with the ongoing DX-88 on-pump cardiothoracic surgery Phase 2 trial,
  known as Kalahari 1, as well as all further development costs associated with
  DX-88 in the licensed indications for the Cubist territory.  Dyax retains exclusive rights to DX-88 in all
  other indications, including its hereditary angioedema program, currently in
  its second Phase 3 trial, as well as for the manufacturing of DX-88.  Except under certain circumstances, Dyax will
  supply Cubist with DX-88 for development and commercialization.  The License Agreement may be terminated by
  Cubist without cause on prior notice to Dyax and by either party in the event
  of a breach of specified provisions of the License Agreement by the other
  party.
  The
  foregoing description of the License Agreement contained in this Item 1.01 does
  not purport to be complete and is qualified in its entirety by reference to the
  complete text of the License Agreement, which will be filed, with confidential
  terms redacted, with the SEC as an exhibit to Cubist's Quarterly Report on Form 10-Q
  for the period ending on June 30, 2008.
  The full
  text of a April 24, 2008 press release announcing Cubist and Dyax entering
  into the License Agreement is attached hereto as Exhibit 99.1.
  Item 9.01 Financial Statements and
  Exhibits.
  (d)          Exhibits.
  99.1
  Press Release dated April 24, 2008
  SIGNATURES
  Pursuant to the requirements of the Securities Exchange Act
  of 1934, the registrant has duly caused this report to be signed on its behalf
  by the undersigned hereunto duly authorized.
  CUBIST PHARMACEUTICALS, INC.
  By:
  /s/ David W. J. McGirr
  David W. J. McGirr
  Senior Vice President and
  Chief Financial Officer
  Dated: April 29, 2008
  2