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                                                                     EXHIBIT 4.4







                      AMENDMENT NO. 1 TO RIGHTS AGREEMENT


         AMENDMENT (this "Amendment"), dated as of February 7, 2003, to the
Rights Agreement (the "Rights Agreement"), dated as of December 3, 1998, between
CELL PATHWAYS, INC., a Delaware corporation (the "Company"), and REGISTRAR AND
TRANSFER COMPANY, a New Jersey corporation (the "Rights Agent"). Capitalized
terms used but not defined herein, unless the context otherwise requires, have
the meanings ascribed to such terms in the Rights Agreement.

         WHEREAS, the Company and the Rights Agent have heretofore executed and
entered into the Rights Agreement;

         WHEREAS, pursuant to Section 27 of the Rights Agreement, the Company
and the Rights Agent shall, if the Company so directs, supplement or amend any
provision of the Rights Agreement in accordance with the provisions of Section
27 thereof;

         WHEREAS, it is proposed that the Company enter into an Agreement and
Plan of Merger (as it may be amended or supplemented from time to time, (the
"OSI Merger Agreement")), among OSI Pharmaceuticals, Inc., a Delaware
corporation ("OSI"), CP Merger Corporation, a Delaware corporation and a
wholly-owned subsidiary of OSI ("Merger Sub") and the Company, which provides
for, among other things, the merger of Merger Sub with and into the Company (the
"OSI Merger");

         WHEREAS, the OSI Merger Agreement contemplates that the Company will
amend the Rights Agreement to the extent necessary to provide that the execution
and delivery of the OSI Merger Agreement will not cause (i) the Rights to become
exercisable under the Rights Agreement, (ii) OSI or Merger Sub or any of their
affiliates to be deemed an Acquiring Person or (ii) the occurrence of the
Distribution Date or the Stock Acquisition Date; and

         WHEREAS, the Board of Directors has determined that it is in the best
interests of the Company and its stockholders to amend the Rights Agreement to
exempt the OSI Merger Agreement and the transactions contemplated by such
agreement from the application of the Rights Agreement.

         NOW, THEREFORE, the Company and the Rights Agent hereby amend the
Rights Agreement as follows:
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          1. The definition of "Acquiring Person" in Section 1(a) of the Rights
Agreement is hereby modified and amended by adding the following sentence at
the end thereof:

                    "Notwithstanding anything in this Agreement to the contrary,
                    none of OSI, a Delaware corporation ("OSI"), Merger Sub (as
                    defined in the OSI Merger Agreement (as defined below)), or
                    any of their Affiliates or Associates, shall be deemed to be
                    an Acquiring Person by virtue of the execution or delivery
                    of the Agreement and Plan of Merger, dated as of February 7,
                    2003 (as the same may be amended from time to time, the "OSI
                    Merger Agreement"), among OSI, CP Merger Corporation, a
                    Delaware corporation and a wholly-owned subsidiary of OSI
                    ("Merger Sub") and the Company, or the consummation of the
                    transactions contemplated by such agreement, including,
                    without limitation, the merger of Merger Sub with and into
                    the Company (the "OSI Merger") or the announcement of the
                    foregoing transactions."

          2. The definition of "Stock Acquisition Date" in Section 1(ee) of the
Rights Agreement is hereby modified and amended by adding the following sentence
at the end thereof:

                    "Notwithstanding anything in this Agreement to the contrary,
                    a Stock Acquisition Date shall not be deemed to have
                    occurred as a result of the execution of the OSI Merger
                    Agreement or the consummation of the transactions
                    contemplated by such agreement, including without
                    limitation, the OSI Merger or the announcement of the
                    foregoing transactions."

          3. Section 3(a) of the Rights Agreement is amended by adding the
following sentence at the end thereof:

                    "Notwithstanding anything in this Agreement to the contrary,
                    a Distribution Date shall not be deemed to have occurred as
                    the result of the execution of the OSI Merger Agreement or
                    the consummation of the transactions contemplated by such
                    agreement, including, without limitation, the OSI Merger or
                    the announcement of the foregoing transactions."

          4. Section 7(a) of the Rights Agreement is hereby modified and
amended to change the reference to "December 14, 2008, or such later date as may
be established by the Board of Directors prior to the expiration of the Rights
(such date, as it may be extended by the Board, the ("Final Expiration Date")"
to "the earlier of (A) December 14, 2008, or such later date as may be
established by the Board of Directors prior to the expiration of the Rights or
(B) immediately prior to the consummation of the


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OSI Merger as contemplated by the OSI Merger Agreement, (the earlier of (i)(A)
and (i)(B) being herein referred to as the "Final Expiration Date")".

          5. Section 30 of the Rights Agreement is amended to add the following
sentence at the end thereof:

                    "Nothing in this Agreement shall be construed to give any
                    holder of Rights or any other Person any legal or equitable
                    rights, remedies or claims under this Agreement by virtue of
                    the execution of the OSI Merger Agreement or by virtue of
                    any of the transactions contemplated by such agreement."

          6. The Rights Agreement is hereby further modified and amended by
adding a new Section 35 immediately after the end or Section 34 thereof to read
in its entirety as follows:

                    "Section 35. Merger Agreement with OSI and Related
                    Transactions. Notwithstanding any other provision of this
                    Rights Agreement, as amended by this Amendment, neither the
                    approval, execution or delivery of the OSI Merger Agreement
                    nor the performance, consummation or announcement of the
                    transactions contemplated by such agreement, is or shall be
                    deemed to be an event described in Section 11(a) (ii) or
                    Section 13 hereof, nor will such performance, consummation
                    or announcement result in the occurrence of a Stock
                    Acquisition Date, a Distribution Date or any other
                    separation of the Rights from the underlying Common Stock,
                    nor entitle or permit the holders of the Rights to exercise
                    the Rights or otherwise affect the rights of the holders of
                    Rights, including giving the holders of the Rights the right
                    to acquire securities of any party to the OSI Merger
                    Agreement."

          7. This Amendment shall become effective as of the date of the OSI
Merger Agreement. If the OSI Merger Agreement is terminated without the
Effective Time (as defined in the OSI Merger Agreement) having occurred, this
Amendment shall be null and void.

          8. This Amendment shall be deemed to be a contract made under the
laws of the State of Delaware and for all purposes shall be governed by and
construed in accordance with the laws of such State applicable to contracts to
be made and performed entirely within such State.

          9. This Amendment may be executed in any number of counterparts, each
of such counterparts shall for all purposes be deemed to be an original, and all
such counterparts shall together constitute but one and the same instrument.

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          10. In all respects not inconsistent with the terms and provisions of
this Amendment, the Rights Agreement is hereby ratified, adopted, approved and
confirmed. In executing and delivering this Amendment, the Rights Agent shall be
entitled to all of the privileges and immunities afforded to the Right Agent
under the terms and conditions of the Rights Agreement.


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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 1
to be duly executed and attested, all as of the date and year first above
written.


CELL PATHWAYS, INC.

By: /s/ Robert J. Towarnicki
    -------------------------------
Name:     Robert J. Towarnicki
Title:    Chief Executive Officer




REGISTRAR AND TRANSFER COMPANY

By: /s/ William P. Tatler
    -------------------------------
Name: William P. Tatler
Title: Vice President