Exhibit 1.1
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                             JOINT FILING AGREEMENT

The undersigned hereby agree that the Statement on this Schedule 13G/A, dated
October 4, 2001, (the "Schedule 13G/A"), with respect to the Common Stock, par
value $0.001 per share, of SangStat Medical Corporation is filed on behalf of
each of us pursuant to and in accordance with the provisions of Rule 13d-1(k)
under the Securities and Exchange Act of 1934, as amended, and that this
Agreement shall be included as an Exhibit to this Schedule 13G/A . Each of the
undersigned agrees to be responsible for the timely filing of the Schedule
13G/A, and for the completeness and accuracy of the information concerning
itself contained therein. This Agreement may be executed in any number of
counterparts, all of which taken together shall constitute one and the same
instrument.

        IN WITNESS WHEREOF, the undersigned have executed this Agreement as of
the 4th day of October, 2001.


                                                         OrbiMed Advisers Inc.

                                                  By: /s/ Samuel D. Isaly
                                                  ----------------------------
                                                  Name:  Samuel D. Isaly
                                                  Title: President

                                                            OrbiMed Advisors LLC

                                                  By: /s/ Samuel D. Isaly
                                                  ----------------------------
                                                  Name:  Samuel D. Isaly
                                                  Title: Managing Member