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Exhibit 10.10(k)

LEASE AMENDMENT "6"

        THIS AMENDMENT is attached to and hereby forms a part of that certain
LEASE ("Lease") made the 1st day of December, 1994, by and between Green, Praver
Et Al ("Landlord") and Anesta Corp., a Delaware Corporation.

        WHEREAS, Anesta Corp. has merged with and is now a wholly owned
subsidiary of Cephalon, Inc. ("Tenant").

        WHEREAS, Tenant and Landlord desire to memorialize their understanding
and to amend the Lease consistent therewith,

        NOW, THEREFORE, in consideration of the mutual covenants and conditions
contained herein and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, Tenant and Landlord agree as
follows:

        1.    LEASE TERM EXTENSION    

        Tenant and Landlord agree to extend the term of Tenant's Lease of Suite
600 of Wiley Post Plaza consisting of 52,199 square feet for an additional
period of three (3) years and three (3) months. The extended term will commence
April 1, 2003 and will end June 30, 2006.

        2.    RENTAL RATES    

        Beginning April 1, 2003, the annual base rent shall be increased for the
first year of the extended term and each year thereafter, effective on each
anniversary date by a percentage equal to the percentage increase in the United
States Department of Labor Statistics New Consumer Price Index for all Urban
Consumers (CPI-U, National Index, 1982-1984 = 100) as published by the United
States Department of Labor, Bureau of Labor Statistics, using as a base the
index for the two months immediately preceding the commencement of the extended
lease term compared to the index for the two months immediately preceding the
anniversary date of the year for which the lease adjustment is being made. The
foregoing notwithstanding, the annual base rent shall not be increased by more
than three percent in any one year.

        3.    ADDITIONAL RENT    

        Tenant shall pay, as additional rent for Suite #600, Tenant's
proportionate share of "Basic Costs Increases" as defined in Section 2.3 of the
Lease. "Tenant's Proportionate Share" shall mean 27.38 percent, which is
determined by dividing the 52,199 square feet being rented by Tenant by 190,628
square feet, the total rentable space in the Project. The additional rent rate
shall be adjusted annually or at such time as there is a significant change in
the costs of any item of additional rent to be paid by Tenant as per Section 2.3
of the Lease.

        4.    VALID AGREEMENTS    

        Tenant and Landlord acknowledge that the Lease (including Amendments 1
through 5) is a valid and enforceable agreement and that the Tenant holds no
claims against Landlord or its agents which might serve as the basis of any
set-off against accruing rent and other charges or any other remedy in law or in
equity. Except as is herein specifically modified and amended or as is necessary
to give meaning and effectuate the terms hereof, the Lease shall remain in full
force and effect, it being understood and agreed that this Amendment, upon
execution, becomes a part of the total Lease.

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        5.    BROKERS    

        Except as herein set out. Tenant represents, and warrants that there are
no claims for brokerage commissions or finder's fees in connection with this
Lease and agrees to indemnify Landlord against and hold it harmless from all
liabilities arising from such claim, including any attorney's fees connected
therewith. Landlord shall pay the brokerage fees and/or commissions payable in
connection with this Lease to Asset Management Services. Inc., who represents
Landlord, pursuant to the applicable listing and/or brokerage agreement between
Landlord and said party.

        6.    AUTHORITY OF SIGNATORIES    

        The persons executing this Lease Amendment "6" on behalf of Landlord and
Tenant, each represent and warrant that he or she has the authority to execute
this Agreement and to bind the respective party. By signing this document on
behalf of Landlord, the, Property Manager (Gregory W. Strong) executing this
Amendment on Landlord's does not, by signing this Amendment in that capacity,
agree to assume any personal liability or to perform any of the obligations
under this Amendment. Such Property Manager is, however, authorized to execute
this Amendment on Landlord's behalf and has the authority to bind Landlord to
perform the terms of this Amendment.

        IN WITNESS WHEREOF, the parties have duly executed this Amendment this
20th day of July, 2001.

LANDLORD: GREEN PRAVER ET AL   TENANT: CEPHALON, INC.

By:
 
/s/  GREGORY W. STRONG      

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By:
 
/s/  J. KEVIN BUCHI      

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Its:
 
Project Manager

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Its:
 
SR. V.P. & CFO

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LEASE AMENDMENT "6"