MILLENNIUM PHARMACEUTICALS INC
EXHIBIT 10.12(B)
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<BR></FONT><FONT SIZE=2><B>Exhibit&nbsp;10.12(b)    <BR>    </B></FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><B>Confidential Materials omitted and filed separately with the<BR>
Securities and Exchange Commission. Asterisks denote omissions.  </B></FONT></P>

<P><FONT SIZE=2>Millennium
Pharmaceuticals,&nbsp;Inc.<BR>
40 Landsdowne Street<BR>
Cambridge<BR>
Massachusetts<BR>
USA </FONT></P>

<P><FONT SIZE=2>Date:
28-02-2005 </FONT></P>

<P><FONT SIZE=2>Dear
Sirs </FONT></P>

<P><FONT SIZE=2>We
refer to the License, Development and Commercialisation Agreement between us dated 22 June, 2004 ("the Agreement") and in particular to Clause&nbsp;8.1 (b)&nbsp;(i) of the Agreement. The
capitalized terms used in this Letter, which are defined in the Agreement, will have the meanings given to them in the Agreement. </FONT></P>

<P><FONT SIZE=2>Notwithstanding
the fact that the Transition Activities and Processes have not yet been completed by Millennium, the parties have agreed that GSK will pay to Millennium the milestone payment of
nineteen million nine hundred thousand dollars (USD $19,900,000) referred to in Clause&nbsp;8.1 (b)&nbsp;(i), given the fact that: </FONT></P>

<UL>
<DL compact>
<DT style='margin-bottom:-11pt;'><FONT SIZE=2>(i)</FONT></DT><DD><FONT SIZE=2>the
Agreement is in full force and effect on and after January&nbsp;1<SUP>st</SUP>, 2005;
<BR><BR></FONT></DD><DT style='margin-bottom:-11pt;'><FONT SIZE=2>(ii)</FONT></DT><DD><FONT SIZE=2>the
CMA has transferred to GSK; and
<BR><BR></FONT></DD><DT style='margin-bottom:-11pt;'><FONT SIZE=2>(iii)</FONT></DT><DD><FONT SIZE=2>GSK
has achieved [**] dollars of gross sales of the Licensed Product in the Territory. </FONT></DD></DL>
</UL>

<P><FONT SIZE=2>Such
payment will be made by GSK within thirty (30)&nbsp;days of receipt by GSK of an invoice for the said amount from Millennium. </FONT></P>

<P><FONT SIZE=2>Millennium
specifically hereby agrees to continue to ensure that the Transition Activities and Processes will be completed in accordance with the terms of the Agreement to the extent that they have
not been completed at the date of signing this letter and that payment of the sum nineteen million nine hundred thousand dollars (USD $19,900,000) in accordance with the above shall not relieve it of
any of its obligations in this respect. </FONT></P>

<P><FONT SIZE=2>Please
confirm your consent to the above by signing and returning the enclosed duplicate copy of this letter initially by fax to Mary Kerr (Fax number +44 (0)&nbsp;208 047 6958) and Lawrence DeGraaf
(Fax number 919 5499074) and thereafter in hard copy form to Lawrence DeGraaf at GlaxoSmithKline, 5 Moore Drive, PO Box 13398, Research Triangle Park, North Carolina 27709-3398. </FONT></P>


<P><FONT SIZE=2>Yours
faithfully </FONT></P>

<P><FONT SIZE=2>For<BR>
GLAXO GROUP LIMITED </FONT></P>

<P><FONT SIZE=2>/s/
Mary Kerr&nbsp;&nbsp;&nbsp;&nbsp;28/2/05 </FONT></P>

<P><FONT SIZE=2>Mary
Kerr<BR>
VP Critical Care Business Unit, Pharma Europe, GlaxoSmithKline </FONT></P>

<P><FONT SIZE=2>Agreed
and accepted<BR>
/s/ Arthur J. Hiller 4/3/05<BR>
Arthur J. Hiller, SVP<BR>
For MILLENNIUM PHARMACEUTICALS, INC </FONT></P>

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