Exhibit 10.5(k)**
                               February 9, 1998
Genelco S.A.
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▇▇▇▇ ▇▇▇▇▇▇▇▇
▇▇▇▇▇▇▇▇▇▇▇
     Re:  Amendment No. 4 to Trademark Agreement
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Gentlemen:
     This letter agreement shall serve as an amendment to the Trademark
Agreement dated January 20, 1993, as amended prior to the date hereof (the
"Trademark Agreement") between Cephalon, Inc. ("Cephalon") and Genelco S.A.
("Genelco"). All capitalized terms not otherwise defined herein shall be used as
defined in the Trademark Agreement.
1.   The term "Territory," for all purposes under the Trademark Agreement is
     hereby expanded to include the Republics of Italy and San Marino
     (collectively, "Italy").
2.   All trademark applications and registered trademarks related to Licensed
     Products and/or the Compound, including the ▇▇▇▇ "Provigil", that are or
     will be filed in the Territory are hereby licensed to Cephalon under the
     Trademark Agreement.
3.   For and in consideration of the expansion of the Territory to include Italy
     under this Amendment No. 4 (and in addition to any compensation payable
     under the Trademark Agreement with respect to other countries in the
     Territory), Cephalon will pay to Genelco, pursuant to Article III(1) of the
     Trademark Agreement, a royalty with respect to Net Sales of a Licensed
     Product in Italy that will be calculated at the rate of [*] of such Net
     Sales.
4.   Each of Cephalon and Genelco hereby restates its respective representations
     and warranties made in the Trademark Agreement, as amended pursuant to this
     letter agreement.
5.   Except as modified by this letter agreement, all provisions of the
     Trademark Agreement are confirmed to be and shall remain in full force and
     effect.
                                   *  THE CONFIDENTIAL MATERIAL CONTAINED HEREIN
                                      HAS BEEN OMITTED AND HAS BEEN FILED
                                      SEPARATELY WITH THE COMMISSION.
**   Certain portions of this exhibit have been omitted based upon a request for
     confidential treatment that has been filed with the Commission. The omitted
     portions have been filed separately with the Commission.
Genelco S.A.
Amendment No. 4
February 9, 1998
Page 2
     If the foregoing is acceptable, please indicate your agreement in the space
provided below.
                                       CEPHALON, INC.
                                       By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇▇
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                                           ▇▇▇▇▇ ▇▇▇▇▇▇▇, ▇▇., Ph.D.
                                           President and Chief Executive Officer
Accepted and agreed to this
23/rd/ day of February, 1998.
GENELCO S.A.
By: /s/ [SIGNATURE ILLEGIBLE]
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