AMENDMENT NO. 5 CONSULTING AGREEMENT This Amendment, effective as of January 1, 1998, is made by and between Seragen, Inc., a Delaware corporation having an address at 97 South Street, Hopkinton, Massachusetts ("Seragen") and John R. Murphy, Ph.D.,...

                       AMENDMENT NO. 5
                     CONSULTING AGREEMENT



       This Amendment, effective as of January 1, 1998, is made by and
       between Seragen, Inc., a Delaware corporation having an address at
       00 Xxxxx Xxxxxx, Xxxxxxxxx, Xxxxxxxxxxxxx ("Seragen") and Xxxx X.
       Xxxxxx, Ph.D., having an address at 000 Xxxxxxxx Xxxxxx, #0X,
       Xxxxxx, Xxxxxxxxxxxxx 00000 (the "Consultant").

       WHEREAS, the parties entered into a Consulting Agreement effective
       January 1, 1992, which was amended effective October 1, 1994,
       October 1, 1995, January 1, 1996, and January 1, 1997
       (collectively, the "Agreement"); and

       WHEREAS the parties now wish to extend the term of the Agreement;

       NOW, THEREFORE, Seragen and the Consultant agree to amend the
       Agreement as follows:

       1. The Agreement shall continue until December 31, 1998.

       2. This Amendment shall be made a part of the Agreement and
       attached to the agreement.  Except as provided in this Amendment,
       all other terms and conditions of the Agreement shall remain in
       force.

          IN WITNESS WHEREOF, the parties have cause this Amendment to
       be executed as of the date first written above.

       ACCEPTED AND AGREED:

       SERAGEN, INC.                              XXXX X. XXXXXX, PH.D.



      /s/Reed R. Prior                            /s/Xxxx X. Xxxxxx, Ph.D.
     --------------------                         -------------------------
      Reed R. Prior
      Chairman and Chief Executive Officer