FOURTH AMENDMENT TO AGREEMENT
This Fourth Amendment to Agreement ("Fourth Amendment") is made and entered into by and between MDS
(Canada) Inc., MDS Nordion division ("Nordion") and IDEC Pharmaceuticals Corporation ("IDEC"), effective
as of June 10, 2003.
A. Nordion and IDEC are parties to that certain Agreement dated May 14, 1999 (the "Isotope Agreement").
B. The Isotope Agreement was subsequently amended by letter agreement between the parties dated January
25, 2000 ("First Amendment"), a letter agreement between the parties dated March 21, 2000 relating to Isotope
dose size ("Isotope Dose Size Letter"), a letter Agreement between the parties dated March 27, 2001 ("Second
Amendment"), and an agreement between the parties dated November 12, 2001 ("Third Amendment"). The
Isotope Agreement, as amended by the First Amendment, Isotope Dose Size Letter, Second Amendment and
Third Amendment are collectively referred to herein as the "Agreement."
C. Nordion and IDEC desire to further amend the Agreement as set forth in this Fourth Amendment.
D. Unless otherwise defined herein capitalized items as used herein shall have the meanings as given thereto in the
NOW THEREFORE in consideration of covenants and agreements herein contained, and subject to the terms
and conditions hereinafter set out the parties agree as follows:
1. Section 3.3 of the Third Amendment shall be amended and restated in its entirety as follows:
"In the event Nordion has not submitted an updated DMF for the KRMF Facility to the FDA on or before
January 12, 2004, IDEC's $55,000,000 US cumulative Commercial Phase minimum purchase commitment set
Section 3.1 above and the $55,000,000 US amount associated with the Cumulative Revenue Date shall each be
reduced by $5,000,000 US and shall continue to be reduced by $5,000,000 US on the 12th day each month
following January 12, 2004 until the updated DMF is submitted, provided, however, in no event shall such
reductions cause the cumulati