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                                                                  EXHIBIT 10.10

THIS AGREEMENT made in duplicate this 15th day of November, 1995,

BETWEEN:          NORDION INTERNATIONAL, INC.
                  a corporation incorporated under the laws of Canada
                  having a place of business at
                  447 March Road, Kanata, Ontario, Canada, K2K 1X8

                                                                    ("Nordion")

AND:              COULTER PHARMACEUTICAL, INC.
                  a corporation incorporated under the laws of Delaware
                  having a place of business at
                  550 California Avenue, Suite 200, Palo Alto,
                  California, U.S.A.

                                                                    ("Coulter").

WHEREAS:
I        Coulter is the owner of certain data, information and technology 
         related to labelling of pharmaceutical compounds;

II       Nordion has expertise in the development of pharmaceutical processes 
         and radiolabelling;

III      The parties desire to jointly carry out the development of 
         radiolabelling of B1 antibody with iodine-131 (I-131) radiochemical in 
         accordance with the terms and conditions set out herein;

IV       Coulter desires to have a clinical supply of I-131 labelled B1 antibody
         prepared to support Phase III clinical trials and for commercialization
         thereafter. Nordion desires to manufacture and distribute I-131 B1
         antibody both for the Phase III clinical trials and for commercial sale
         after regulatory approval.

NOW THEREFORE, in consideration of the mutual covenants and agreements herein 
contained, and subject to the terms and conditions hereinafter set out, the 
parties hereto agree as follows:

                                       1.
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1.       Scope and Object

         The scope and object of this Agreement is to carry out the joint
         development of a pharmaceutical process for I-131 B1 antibody (the
         "Project") in accordance with the development responsibilities and
         obligations attributed to each of the parties as set out in Schedule A,
         which shall serve as a guideline in carrying out this Agreement.

2.       Term

         The Project and this Agreement shall be deemed to have commenced on
         July 10, 1995, which Project may be terminated by either party at any
         time upon fifteen (15) days prior written notice.

         It is understood and acknowledged that the time for completion and
         sequence for carrying out the Project as set out in Schedule A shall
         serve only as a guide to achieving the milestones set out in said
         schedule.

3.       Development and Facility Phases

         The Project shall be divided into the following two phases, both of
         which are anticipated to be completed within fifteen (15) months 
         of the date of commencement of the Project:

         (i)      Development Phase: Items 2-22, as set out on Schedule A; and

         (ii)     Facility Phase:  Items 23-30, as set out on Schedule A.

         This Agreement shall only concern itself with the carrying out of the
         Development Phase of the Project. It is anticipated that the Facility
         Phase of the Project will cost approximately [*] United States
         dollars ($US [*] ), subject however, to any new information acquired
         during the Development Phase. The

*   Certain confidential information contained in this document, marked by
    brackets, has been omitted and filed with the Securities and Exchange
    Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

                                       2.
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         terms and conditions upon which the Facility Phase will be carried out
         will be agreed by the parties under separate contract, to be prepared
         and negotiated during the term of the Development Phase.

         Nordion shall have a single right of first negotiation for the right to
         carry out the Facility Phase and to provide commercial supply of
         radiolabelled I-131 B1 antibody. Such negotiations shall be initiated
         by Coulter in writing and shall be ongoing for a period of at least
         sixty (60) days. Coulter shall not, subsequent to successful or
         unsuccessful negotiations with Nordion, offer to any third party,
         rights to carry out the Facility Phase and to supply for clinical
         trials and/or commercial supply, on terms less favorable to Coulter
         than those offered by Nordion. Nordion's right of first negotiation and
         this paragraph shall survive termination or completion of this
         Agreement for a period of two (2) years.

         Clinical trial sites carrying out the radiolabelling of I-131 B1
         antibody for the limited purpose of their own in-house use during
         clinical trials shall not be a contravention of Nordion's right of
         first refusal. 

4.       Development Activities

         Nordion and Coulter shall respectively carry out their obligations
         described and attributed in Schedule A, it being understood that some
         development activities may be delayed to the extent that such activity
         is premised on the work or provision of data, information or technology
         by the other party.

        
                                       3.
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5.       Payments

         In consideration of Nordion performing the development services under
         the Project, Coulter shall pay Nordion in accordance with the rates set
         out in Schedule B, within thirty (30) days of receipt of an invoice
         from Nordion. Such invoice shall, unless otherwise agreed, be payable
         in United States currency.

         In addition to the rates charged to carry out the development services,
         Nordion shall invoice Coulter on a monthly basis, during the term of
         this Agreement, for all equipment purchased and materials consumed in
         carrying out the development activities, on the basis of invoice
         price plus 5% administration.
                                                                  
         Nordion shall keep proper records of the time spent, expenses incurred
         and materials consumed in performance of the Project. Subject to
         reasonable notice, such records shall be open to audit and inspection
         by Coulter. Nordion shall furnish to Coulter all additional information
         about such records as Coulter may reasonably require.

6.       License

         Coulter hereby provides to Nordion a non-exclusive, non-transferable,
         royalty-free license during the Project to use the data, information
         and technology, provided by Coulter related to B1 antibody labelling
         for the limited purpose of assisting Nordion in carrying out its
         obligations set out in this Agreement.

         Coulter represents, warrants and covenants that (i) it is the owner of
         such data, information and technology, (ii) the data, information and
         technology do not, to Coulter's best information and belief, infringe
         any patents, copyright or other industrial or intellectual property
         rights of third parties, (iii) it has the right to provide the license
         and right to permit Nordion to use the data, information and 


                                       4.
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         technology to carry out the Project as contemplated herein; and (iv)
         has not received any notice of adverse claim or infringement of any
         patent.

         Coulter shall indemnify and hold Nordion harmless, from and against,
         any allegations, claims, actions or damages arising from infringement
         of third party copyright, patents, technology, or other intellectual
         property rights, resulting from Nordion's use of any data, information
         or technology, as provided by Coulter hereunder. This indemnity shall
         survive termination or completion of this Agreement.

7.       Ownership of Work Performed

         a) For purposes of this section, "Background Technology" shall mean all
         Nordion proprietary technology, including patents, know-how,
         techniques, methods, processes and trade secrets which Nordion owns or
         uses in performing under this Agreement, or which is licensed to
         Nordion and which is in existence in the form of a writing, prototype
         or can otherwise be demonstrated to be the property of Nordion, prior
         to the effective date of this Agreement.

         b) Nordion agrees and Coulter acknowledges, that any and all ideas,
         improvements, inventions and works of authorship conceived, written
         created or first reduced to practice in the performance of the Project,
         except to the extent that it relates to or embodies the Background
         Technology or improvements to the Background Technology, shall be the
         sole and exclusive property of Coulter and Nordion hereby assigns to
         Coulter all right, title and interest in and to any and all such ideas,
         improvements, inventions and works of authorship.

         c) Nordion further agrees that, except for Nordion's rights in
         Background Technology which rights shall remain the sole property of
         Nordion, Coulter is and

                                       5.
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         shall be vested with all right, title and interest, including patent,
         copyright and trade secret rights in all of Nordion's work produced in
         carrying out the Project.

         d) Coulter hereby grants Nordion a transferable, world-wide,
royalty-free, perpetual license to exploit all ideas, improvements, inventions
and works of authorship assigned or vested to Coulter as described in section
7.b) and 7.c) for [*].

         This section shall survive the termination of this Agreement for any
         reason including expiration of term.

8.       Coulter Proprietary Information

         All data, information, or technology supplied to Nordion by Coulter to
         assist Nordion in carrying out its obligations hereunder, shall remain
         the property of Coulter and shall be returned by Nordion to Coulter
         upon completion or termination of the Project.

9.       Patent Applications

         a) Nordion shall execute all papers, including patent applications,
         invention assignments and copyright assignments, and otherwise shall
         assist Coulter as reasonably required to perfect in Coulter the rights,
         title and other interests in Nordion's work product expressly granted
         to Coulter under this Agreement. Costs related to such assistance, if
         required, shall be paid by Coulter.

         b) Notwithstanding any other provision of this Agreement, in the event
         that Nordion requests in writing that Coulter file, maintain and
         prosecute a patent application pertaining to rights granted to Nordion
         pursuant to Section 7. d) hereof, then Coulter shall have thirty
         (30) days to inform Nordion whether or not such



* Certain confidential information contained in this document, marked by
  brackets, has been omitted and filed with the Securities and Exchange
  Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

                                       6.
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         application will be made. In the event that Coulter fails to inform
         Nordion of its intent to proceed with the requested patent application
         within such thirty (30) day period, then Nordion shall have the sole
         right to proceed with the filing, prosecution and maintenance of such
         patent application, at its sole expense. Any patent resulting therefrom
         shall be the sole property of Nordion, subject only to Coulter's
         non-exclusive, royalty-free and world-wide right to use and sublicense
         the use of such patent in connection with products based on the B-1
         antibody radiolabelled with 1-131. Coulter shall execute all papers,
         including patent applications and invention assignments, and otherwise
         shall assist Nordion as reasonably required to perfect in Nordion the
         patent rights described in this section 9.b).

         c) This section 9 shall survive the termination of this Agreement for
         any reason, including expiration of term.

10.      Disclosure of Technology

         It is agreed that disclosure of data, information or technology by
         Nordion or Coulter, to the other, during the Project shall not, except
         to the extent granted herein, constitute any grant, option or license
         under any patent, technology or other rights, held by Nordion or
         Coulter.


                                       7.
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11.      Progress Reports

         Nordion will provide written reports to Coulter, on a monthly basis
         (prior to the 21st day of the following month), setting out the
         progress against milestones as set out in Schedule A.

12.      Project Completion Costs

         Any expense related to labor or materials which exceed the proposed
         estimated project costs of $US375,000 will be subject to the prior 
         written approval of Coulter.

13.      Confidentiality

         Except as regards rights in work product obtained by Coulter in Section
         7(b) and 7(c) during the term of this Agreement and for a period of ten
         (10) years thereafter, each party hereto shall maintain in confidence
         all technology including Background Technology, know-how, data,
         processes, methods, techniques, formulas, test data and other
         information ("Confidential Information") disclosed to such party by the
         other party which, if written, is marked as "Confidential" by the
         disclosing party or, if verbal, is reduced to writing and marked
         "Confidential" by the disclosing party, within fifteen (15) days of
         verbal disclosure. This obligation of confidentiality shall not apply
         to the extent that it can be established by the party in receipt of
         such information, that the information:

         i)  was already known to the receiving party at the time of disclosure;

         ii) was generally available to the public or otherwise part of the
             public domain at the time of its disclosure;


                                       8.
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         iii) became generally available to the public or otherwise part of the
              public domain after its disclosure to the receiving party through
              no act or omission of the receiving party;

         iv)  was disclosed to the receiving party by a third party who had no
              obligation to restrict disclosure of such information; or

         v)   was independently developed by the receiving party without any use
              of Confidential Information of the disclosing party.

              This section shall survive termination or completion of this 
              Agreement in accordance with its terms.

14.      Indemnity

         Nordion and Coulter, as the case may be, shall indemnify and hold
         harmless the other from and against any and all costs, claims,
         judgments or other expenses, including reasonable attorney fees,
         arising as a result of damages claimed by third parties, in tort,
         contract or other legal theory, occasioned by Nordion's or Coulter's
         negligence or that of their respective employees or agents, in carrying
         out their obligations hereunder. This section shall survive termination
         or completion of this Agreement.

                                       9.
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15.      Termination

         Upon termination of this Agreement, Nordion shall forthwith discontinue
         its development activities under the Project and shall cancel all
         commitments pertaining thereto in an orderly and economic manner. If
         this Agreement is so terminated, Coulter shall be liable to pay to
         Nordion for development services rendered, equipment purchased (or
         committed to be purchased) and materials consumed, prior to the
         effective date of termination. In the event of such termination neither
         Nordion nor Coulter shall have any other right of action on account of
         such termination.

16.      Notice

         Any notice to be sent to a party hereunder shall be forwarded to:


         Nordion at:        447 March Road

                            Kanata, Ontario, Canada

                            K2K 1X8

         Attention:         Vice-President

                            Technology and Business Development

         Coulter at:        550 California Avenue, Suite 200, Palo Alto

                            California, U.S.A.

         Attention:         Vice President, Business Development

         Any notice required or authorized to be given by a party to the other
         in accordance with the provisions of this Agreement shall, unless
         otherwise specifically stipulated, be in writing and delivered
         personally, by telegram or electronic facsimile and confirmed by
         registered mail.

                                      10.
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17.      Assignment

         Neither Nordion nor Coulter shall assign any portion of this Agreement
         without the written approval of the other party, which approval shall
         not be unreasonably withheld. Nordion shall be entitled to subcontract
         to third parties any of its obligations set out in this Agreement in
         order to carry out the Project; provided, however, that Nordion may not
         subcontract any portion of this Agreement unless such subcontractor
         shall agree to be bound by the provisions hereof pertaining to
         ownership of work performed and confidentiality.

18.      Compliance

         The Project shall be carried out in compliance with all applicable 
         laws, by-laws, rules, regulations and orders of federal, provincial or
         municipal governments or manifestations thereof.

19.      Non-Waiver

         Failure by either party to enforce at any time any of the provisions of
         this Agreement shall not be construed as a waiver of its rights
         hereunder. Any waiver of a breach of any provision hereof shall not
         affect either party's rights in the event of any additional breach.

20.      Force Majeure

         Neither party hereto shall incur any liability to the other in the
         event that it is delayed in the performance of its obligations
         hereunder solely by force majeure. For the purpose of this Agreement,
         "force majeure" shall mean any cause of delay beyond the reasonable
         control of the party liable to perform unless conclusive evidence to
         the contrary is provided and shall include, but not by way of
         limitation, strikes, lockouts, dots, sabotage, acts of war or piracy,
         destruction of essential 

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         equipment by fire, explosion, storm, flood, earthquake, or delay caused
         by failure of power supplies or transport facilities.

21.      Applicable Law

         This Agreement shall be governed and construed in accordance with the
         laws of the Province of Ontario, Canada, without reference to its
         conflicts of laws. The venue for any legal proceeding arising out of
         this Agreement shall be in the Province of Ontario, Canada.

IN WITNESS WHEREOF the parties hereto have executed this Agreement on the date 
first hereinabove written.

                                     NORDION INTERNATIONAL INC.

                                     By:   /s/  David Evans
                                         --------------------------------------
                                           David Evans, Vice President,
                                           Business Development and Technology

                                     COULTER PHARMACEUTICAL, INC.

                                     By:   /s/  Bobbie F. Wallace
                                         --------------------------------------
                                           Bobbie F. Wallace
                                           Vice President, Operations

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                                   SCHEDULE A

                                      [*]

* Certain confidential information contained in this document, marked by
  brackets, has been omitted and filed with the Securities and Exchange
  Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.


                                       i
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                                   SCHEDULE A

                                      [*]

* Certain confidential information contained in this document, marked by
  brackets, has been omitted and filed with the Securities and Exchange
  Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.


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                                   SCHEDULE B

                                      RATES

Management and documentation              $US [*] per hour
                                     


Engineering design and laboratory work    $US [*] per hour
                                         

* Certain confidential information contained in this document, marked by
  brackets, has been omitted and filed with the Securities and Exchange
  Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.


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