Document:

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                                                                   Exhibit 10.14

                               IMMUNEX CORPORATION

                             1993 STOCK OPTION PLAN

                    As Amended and Restated on April 25, 2000

Section 1.  Purpose

         The purpose of the Amended and Restated 1993 Stock Option Plan (this
"Plan") is to provide a means whereby selected employees, directors and officers
of Immunex Corporation (the "Company"), or of any parent or subsidiary (as
defined in subsection 5.8 and referred to hereinafter as "related corporations")
thereof, may be granted incentive stock options and/or nonqualified stock
options to purchase the Common Stock (as defined in Section 3) of the Company,
in order to attract and retain the services or advice of such employees,
directors and officers and to provide added incentive to such persons by
encouraging stock ownership in the Company.

Section 2.  Administration

         This Plan shall be administered by a Stock Option Plan Administration
Committee (the "Committee" or "Plan Administrator") appointed by the Board of
Directors of the Company (the "Board") consisting of two or more members of the
Board. If and so long as the Common Stock is registered under Section 12(b) or
12(g) of the Securities Exchange Act of 1934, as amended from time to time (the
"Exchange Act"), the Board shall consider in selecting the Plan Administrator
and the membership of any committee acting as Plan Administrator of the Plan
with respect to any persons subject or likely to become subject to Section 16
under the Exchange Act the provisions regarding (a) "outside directors" as
contemplated by Section 162(m) of the Internal Revenue Code of 1986, as amended
(the "Code"), and (b) "nonemployee directors" as contemplated by Rule 16b-3
under the Exchange Act. The Board may delegate the responsibility for
administering the Plan with respect to designated classes of eligible
Participants to different committees, subject to such limitations as the Board
deems appropriate. Committee members shall serve for such term as the Board may
determine, subject to removal by the Board at any time. To the extent consistent
with applicable law, the Board may authorize one or more senior executive
officers of the Company to grant options to specified eligible persons, within
the limits specifically prescribed by the Board. All delegations of authority by
the Board pursuant to this Section 2 shall be subject to the procedural
requirements of Section 4.03 of the Amended and Restated Governance Agreement
among American Cyanamid Company, Lederle Oncology Corporation and Immunex
Corporation dated as of December 15, 1992.

         2.1      Procedures

         The Board shall designate one of the members of the Plan Administrator
as chairman. The Plan Administrator may hold meetings at such times and places
as it shall determine. The acts of a majority of the members of the Plan
Administrator present at meetings at which a quorum exists, or acts reduced to
or approved in writing by all Plan Administrator members, shall be valid acts of
the Plan Administrator.

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         2.2      Responsibilities

         Except for the terms and conditions explicitly set forth in this Plan,
the Plan Administrator shall have the authority, in its discretion, to determine
all matters relating to the options to be granted under this Plan, including
selection of the individuals to be granted options, the number of shares to be
subject to each option, the exercise price, and all other terms and conditions
of the options. Grants under this Plan need not be identical in any respect,
even when made simultaneously. The interpretation and construction by the Plan
Administrator of any terms or provisions of this Plan or any option issued
hereunder, or of any rule or regulation promulgated in connection herewith,
shall be conclusive and binding on all interested parties, so long as such
interpretation and construction with respect to incentive stock options
correspond to the requirements of Section 422 of the Code, the regulations
thereunder and any amendments thereto.

         2.3      Section 16(b) Compliance and Bifurcation of Plan

         Notwithstanding anything in this Plan to the contrary, the Board, in
its absolute discretion, may bifurcate this Plan so as to restrict, limit or
condition the use of any provision of this Plan to participants who are officers
and directors subject to Section 16 of the Exchange Act without so restricting,
limiting or conditioning this Plan with respect to other participants.

Section 3.  Stock Subject to This Plan

         The stock subject to this Plan shall be the Company's Common Stock, par
value $.01.01 per share (the "Common Stock"),presently authorized but unissued.
Subject to adjustment as provided in Section 7, the aggregate amount of Common
Stock to be delivered upon the exercise of all options granted under this Plan
shall not exceed 74,703,204/1/ shares. If any option granted under this Plan
shall expire or be surrendered, exchanged for another option, cancelled or
terminated for any reason without having been exercised in full, the unpurchased
shares subject thereto shall thereupon again be available for purposes of this
Plan, including for replacement options which may be granted in exchange for
such expired, surrendered, exchanged, cancelled or terminated options.

Section 4.  Eligibility

         An incentive stock option may be granted only to an individual who, at
the time the option is granted, is an employee of the Company or any related
corporation. A nonqualified stock option may be granted to any employee,
director or officer of the Company or any related corporation, whether an
individual or an entity. Any party to whom an option is granted under this Plan
shall be referred to hereinafter as an "Optionee."

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         /1/ The original number of Shares in this Plan was 6,225,267. This
number was adjusted to 74,703,204 as a result of a 2-for-1 stock split on March
25, 1999, a 2-for-1 stock split on August 26, 1999 and a 3-for-1 stock split on
March 20, 2000.

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Section 5.  Terms and Conditions of Options

         Options granted under this Plan shall be evidenced by written
agreements which shall contain such terms, conditions, limitations and
restrictions as the Plan Administrator shall deem advisable and which are not
inconsistent with this Plan. Notwithstanding the foregoing, options shall
include or incorporate by reference the following terms and conditions:

         5.1      Number of Shares and Price

         The maximum number of shares that may be purchased pursuant to the
exercise of each option and the price per share at which such option is
exercisable (the "exercise price") shall be as established by the Plan
Administrator; provided, however, that the maximum number of shares with respect
to which an option or options may be granted to any Optionee in any one fiscal
year of the Company shall not exceed 2,400,000/2/ shares (the "Maximum Annual
Optionee Grant"); however, the Company may make additional one-time grants of up
to 2,400,000/3/ shares to newly hired employees, provided further that the Plan
Administrator shall act in good faith to establish the exercise price which
shall be not less than the fair market value per share of the Common Stock at
the time the option is granted with respect to incentive stock options and not
less than the par value per share of the Common Stock at the time the option is
granted with respect to nonqualified stock options and also provided that, with
respect to incentive stock options granted to greater than 10% shareholders, the
exercise price shall be as required by subsection 6.1.

         5.2      Term and Maturity

         Subject to the restrictions contained in Section 6 with respect to
granting incentive stock options to greater than 10% shareholders, the term of
each incentive stock option shall be as established by the Plan Administrator
and, if not so established, shall be 10 years from the date it is granted but in
no event shall it exceed 10 years. The term of each nonqualified stock option
shall be as established by the Plan Administrator and, if not so established,
shall be 10 years. To ensure that the Company or related corporation will
achieve the purpose and receive the benefits contemplated in this Plan, any
option granted to any Optionee hereunder shall, unless the condition of this
sentence is waived or modified in the agreement evidencing the option or by
resolution adopted at any time by the Plan Administrator, be exercisable
according to the following schedule:

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         /2/ This number was originally 200,000, but was adjusted to 2,400,000
as a result of a 2-for-1 stock split on March 25, 1999, a 2-for-1 stock split on
August 26, 1999 and a 3-for-1 stock split on March 20, 2000.

         /3/ This number was originally 200,000, but was adjusted to 2,400,000
as a result of a 2-for-1 stock split on March 25, 1999, a 2-for-1 stock split on
August 26, 1999 and a 3-for-1 stock split on March 20, 2000.

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   Period of Optionee's Continuous                   Portion of Total Option
  Relationship With the Company or                    Which Is Exercisable
  Related Corporation From the Date             --------------------------------
       the Option Is Granted
----------------------------------------

             after one year                                    20%

             after two years                                   40%

            after three years                                  60%

            after four years                                   80%

            after five years                                  100%

         Notwithstanding the foregoing, for any option granted under the Plan,
the option shall become 100% vested and exercisable on the date of termination
of an Optionee's employment or service relationship with the Company or a
related corporation on account of the Optionee's death, provided that the
Optionee has been in the continuous employment of or service to the Company or a
related corporation for at least two years at the date of such Optionee's death.

         5.3      Exercise

         Subject to the vesting schedule described in subsection 5.2, each
option may be exercised in whole or in part at any time and from time to time;
provided, however, that no fewer than 20% of the shares purchasable under the
option (or the remaining shares then purchasable under the option, if less than
20%) may be purchased upon any exercise of option rights hereunder and that only
whole shares will be issued pursuant to the exercise of any option and that the
exercise price shall not be less than the par value per share of the Common
Stock at the time the option is exercised. During an Optionee's lifetime, any
options granted under this Plan are personal to him or her and are exercisable
solely by such Optionee. Options shall be exercised by delivery to the Company
of notice of the number of shares with respect to which the option is exercised,
together with payment of the exercise price.

         5.4      Payment of Exercise Price

         Payment of the option exercise price shall be made in full at the time
the notice of exercise of the option is delivered to the Company and shall be in
cash, bank certified or cashier's check or personal check (unless at the time of
exercise the Plan Administrator in a particular case determines not to accept a
personal check) for the Common Stock being purchased.

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         The Plan Administrator can determine at any time before exercise that
additional forms of payment will be permitted. To the extent permitted by
applicable laws and regulations (including, but not limited to, federal tax and
securities laws and regulations and state corporate law), and unless the Plan
Administrator determines otherwise, an option also may be exercised, either
singly or in combination with one or more of the alternative forms of payment
authorized by this Section 5.4 by:

          (a) tendering (either actually or by attestation) shares of stock of
the Company held by an Optionee having a fair market value equal to the exercise
price, such fair market value to be determined in good faith by the Plan
Administrator; provided, however, that payment in stock held by an Optionee
shall not be made unless the stock shall have been owned by the Optionee for a
period of at least six months (or any shorter period necessary to avoid a charge
to the Company's earnings for financial accounting purposes); or

          (b) delivery of a properly executed exercise notice, together with
irrevocable instructions to a broker, all in accordance with the regulations of
the Federal Reserve Board, to promptly deliver to the Company the amount of sale
or loan proceeds to pay the exercise price and any federal, state or local
withholding tax obligations that may arise in connection with the exercise.

          In addition, the exercise price for shares purchased under an option
may be paid, either singly or in combination with one or more of the alternative
forms of payment authorized by this Section 5.4, by (y) delivery of a
full-recourse promissory note executed by the Optionee; provided that (i) such
note delivered in connection with an incentive stock option shall, and such note
delivered in connection with a nonqualified stock option may, in the sole
discretion of the Plan Administrator, bear interest at a rate specified by the
Plan Administrator but in no case less than the rate required to avoid
imputation of interest (taking into account any exceptions to the imputed
interest rules) for federal income tax purposes, (ii) the Plan Administrator in
its sole discretion shall specify the term and other provisions of such note at
the time an incentive stock option is granted or at any time prior to exercise
of a nonqualified stock option, (iii) the Plan Administrator may require that
the Optionee pledge to the Company for the purpose of securing the payment of
such note the shares of Common Stock to be issued to the Optionee upon exercise
of the option and may require that the certificate representing such shares be
held in escrow in order to perfect the Company's security interest, and (iv) the
Plan Administrator in its sole discretion may at any time restrict or rescind
this right upon notification to the Optionee; or (z) such other consideration as
the Plan Administrator may permit.

         5.5      Withholding Tax Requirement

         The Company or any related corporation shall have the right to retain
and withhold from any payment of cash or Common Stock under this Plan the amount
of taxes required by any government to be withheld or otherwise deducted and
paid with respect to such payment. At its discretion, the Company may require an
Optionee receiving shares of Common Stock to reimburse the Company for any such
taxes required to be withheld by the Company and withhold any distribution in
whole or in part until the Company is so reimbursed. In lieu thereof, the
Company shall have the right to withhold from any other cash amounts due or to
become due from the Company to the Optionee an amount equal to such taxes. The
Company may also retain and withhold or the Optionee may elect, subject to
approval by the Company at its sole discretion, to have the Company retain and
withhold a number of shares having a market value not less than the amount of
such taxes required to be withheld by the Company to reimburse the Company for
any such taxes and cancel (in whole or in part) any such shares so withheld.

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         5.6      Holding Periods

                  5.6.1       Securities Exchange Act Section 16

         If an individual subject to Section 16 of the Exchange Act sells shares
of Common Stock obtained upon the exercise of a stock option within six months
after the date the option was granted, such sale may result in short-swing
profit recovery under Section 16(b) of the Exchange Act.

                  5.6.2       Taxation of Stock Options

         The Plan Administrator may require an Optionee to give the Company
prompt notice of any disposition of shares of Common Stock acquired by the
exercise of an incentive stock option prior to the expiration of two years after
the date of grant of the option and one year from the date of exercise.

         5.7      Nontransferability of Options

         Options granted under this Plan and the rights and privileges conferred
hereby may not be transferred, assigned, pledged or hypothecated in any manner
(whether by operation of law or otherwise, other than by will or by the
applicable laws of descent and distribution and shall not be subject to
execution, attachment or similar process. Any attempt to transfer, assign,
pledge, hypothecate or otherwise dispose of any option under this Plan or of any
right or privilege conferred hereby, contrary to the Code or to the provisions
of this Plan, or the sale or levy or any attachment or similar process upon the
rights and privileges conferred hereby shall be null and void. Notwithstanding
the foregoing, if the Company permits, an Optionee may, during the Optionee's
lifetime, designate a person who may exercise the option after the Optionee's
death by giving written notice of such designation to the Plan Administrator.
Such designation may be changed from time to time by the Optionee by giving
written notice to the Plan Administrator revoking any earlier designation and
making a new designation.

         5.8      Termination of Relationship

         If the Optionee's relationship with the Company or any related
corporation ceases for any reason other than termination for cause, death or
total disability, and unless by its terms the option sooner terminates or
expires, then the portion of the option which is not exercisable at the time of
such cessation shall terminate immediately upon such cessation, unless the Plan
Administrator determines otherwise, and the Optionee may exercise, for a
three-month period, that portion of the option which is exercisable at the time
of such cessation, and shall terminate at the end of such period following such
cessation as to all shares for which it has not theretofore been exercised,
unless the Plan Administrator determines otherwise. The Plan Administrator shall
have sole discretion in a particular circumstance to extend the exercise period
following such cessation to any date up to the termination or expiration of the
option. If, however, in the case of an incentive stock option, the Optionee does
not exercise the Optionee's option within three months after cessation of
employment, the option will no longer qualify as an incentive stock option under
the Code.

         If an Optionee is terminated for cause, any option granted hereunder
shall automatically terminate as of the first discovery by the Company of any
reason for termination for cause, and such Optionee shall thereupon have no
right to purchase any shares pursuant to such option. "Termination for cause"
shall mean dismissal for dishonesty, conviction or confession of a crime
punishable by law (except minor violations), fraud, misconduct or disclosure of
confidential information.

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         If an Optionee's relationship with the Company or any related
corporation is suspended pending an investigation of whether or not the Optionee
shall be terminated for cause, all the Optionee's rights under any option
granted hereunder likewise shall be suspended during the period of
investigation.

         If an Optionee's relationship with the Company or any related
corporation ceases because of a total disability, the portion of the Optionee's
option that is exercisable at the time of such cessation shall not terminate or,
in the case of an incentive stock option, cease to be treated as an incentive
stock option until the end of the 12-month period following such cessation
(unless by its terms it sooner terminates and expires). As used in this Plan,
the term "total disability" refers to a mental or physical impairment of the
Optionee which is expected to result in death or which has lasted or is expected
to last for a continuous period of 12 months or more and which causes the
Optionee to be unable, in the opinion of the Company and two independent
physicians, to perform his or her duties for the Company and to be engaged in
any substantial gainful activity. Total disability shall be deemed to have
occurred on the first day after the Company and the two independent physicians
have furnished their opinion of total disability to the Plan Administrator.

         Options granted under this Plan shall not be affected by any change of
relationship with the Company so long as the Optionee continues to be an
employee, director, officer, agent, consultant, advisor or independent
contractor of the Company or of a related corporation. The Plan Administrator,
in its absolute discretion, may determine all questions of whether particular
leaves of absence constitute a termination of services; provided, however, that
with respect to incentive stock options, such determination shall be subject to
any requirements contained in the Code. The foregoing notwithstanding, with
respect to incentive stock options, employment shall not be deemed to continue
beyond the first 90 days of such leave, unless the Optionee's reemployment
rights are guaranteed by statute or by contract.

         As used herein, the term "related corporation," when referring to a
subsidiary corporation, shall mean any corporation (other than the Company) in,
at the time of the granting of the option, an unbroken chain of corporations
ending with the Company, if stock possessing 50% or more of the total combined
voting power of all classes of stock of each of the corporations other than the
Company is owned by one of the other corporations in such chain. When referring
to a parent corporation, the term "related corporation" shall mean any
corporation in an unbroken chain of corporations ending with the Company if, at
the time of the granting of the option, each of the corporations other than the
Company owns stock possessing 50% or more of the total combined voting power of
all classes of stock in one of the other corporations in such chain.

         5.9      Death of Optionee

         If an Optionee dies while he or she has a relationship with the Company
or any related corporation or within the three-month period (or 12-month period
in the case of totally disabled Optionees) following cessation of such
relationship, any option held by such Optionee to the extent that the Optionee
would have been entitled to exercise such option, may be exercised within one
year after his or her death by the personal representative of his or her estate
or by the person or persons to whom the Optionee's rights under the option shall
pass by will or by the applicable laws of descent and distribution.

         5.10     No Status As Shareholder

         Neither the Optionee nor any party to which the Optionee's rights and
privileges under the option may pass shall be, or have any of the rights or
privileges of, a shareholder of the Company with respect to any of the shares
issuable upon the exercise of any option granted under this Plan unless and
until such option has been exercised.

<PAGE>

         5.11     Continuation of Relationship

         Nothing in this Plan or in any option granted pursuant to this Plan
shall confer upon any Optionee any right to continue in the employ or other
relationship of the Company or of a related corporation, or to interfere in any
way with the right of the Company or of any such related corporation to
terminate his or her employment or other relationship with the Company at any
time.

         5.12     Modification and Amendment of Option

         Subject to the requirements of Section 422 of the Code with respect to
incentive stock options and to the terms and conditions and within the
limitations of this Plan, the Plan Administrator may modify or amend outstanding
options granted under this Plan. The modification or amendment of an outstanding
option shall not, without the consent of the Optionee, impair or diminish any of
his or her rights or any of the obligations of the Company under such option.
Except as otherwise provided in this Plan, no outstanding option shall be
terminated without the consent of the Optionee. Unless the Optionee agrees
otherwise, any changes or adjustments made to outstanding incentive stock
options granted under this Plan shall be made in such a manner so as not to
constitute a "modification" as defined in Section 424(h) of the Code and so as
not to cause any incentive stock option issued hereunder to fail to continue to
qualify as an incentive stock option as defined in Section 422(b) of the Code.

         5.13     Limitation on Value for Incentive Stock Options

         As to all incentive stock options granted under the terms of this Plan,
to the extent that the aggregate fair market value of the stock (determined at
the time the incentive stock option is granted) with respect to which incentive
stock options are exercisable for the first time by the Optionee during any
calendar year (under this Plan and all other incentive stock option plans of the
Company, a related corporation or a predecessor corporation) exceeds $100,000,
such options shall be treated as nonqualified stock options. The previous
sentence shall not apply if the Internal Revenue Service issues a statutory
change, public rule, issues a private ruling to the Company, any Optionee or any
legatee, personal representative or distributee of an Optionee or issues
regulations changing or eliminating such annual limit.

Section 6.  Greater Than 10% Shareholders

         6.1      Exercise Price and Term of Incentive Stock Options

         If incentive stock options are granted under this Plan to employees who
own more than 10% of the total combined voting power of all classes of stock of
the Company or any related corporation, the term of such incentive stock options
shall not exceed five years and the exercise price shall be not less than 110%
of the fair market value of the Common Stock at the time the incentive stock
option is granted. This provision shall control notwithstanding any contrary
terms contained in an option agreement or any other document.

<PAGE>

         6.2      Attribution Rule

         For purposes of subsection 6.1, in determining stock ownership, an
employee shall be deemed to own the stock owned, directly or indirectly, by or
for his or her brothers, sisters, spouse, ancestors and lineal descendants.
Stock owned, directly or indirectly, by or for a corporation, partnership,
estate or trust shall be deemed to be owned proportionately by or for its
shareholders, partners or beneficiaries. If an employee or a person related to
the employee owns an unexercised option or warrant to purchase stock of the
Company, the stock subject to that portion of the option or warrant which is
unexercised shall not be counted in determining stock ownership. For purposes of
this Section 6, stock owned by an employee shall include all stock actually
issued and outstanding immediately before the grant of the incentive stock
option to the employee.

Section 7.  Adjustments Upon Changes in Capitalization

         The aggregate number and class of shares for which options may be
granted under this Plan, the number and class of shares covered by each
outstanding option and the exercise price per share thereof (but not the total
price), shall all be proportionately adjusted for any increase or decrease in
the number of issued shares of Common Stock resulting from a split-up or
consolidation of shares or any like capital adjustment, or the payment of any
stock dividend.

         7.1      Effect of Liquidation or Reorganization

                  7.1.1      Cash, Stock or Other Property for Stock

         Except as provided in subsection 7.1.2, upon a merger (other than a
merger of the Company in which the holders of Common Stock immediately prior to
the merger have the same proportionate ownership of Common Stock in the
surviving corporation immediately after the merger), consolidation, acquisition
of property or stock, separation, reorganization (other than a mere
reincorporation or the creation of a holding company) or liquidation of the
Company, as a result of which the shareholders of the Company receive cash,
stock or other property in exchange for or in connection with their shares of
Common Stock, any option granted hereunder shall terminate, but the Optionee
shall have the right immediately prior to any such merger, consolidation,
acquisition of property or stock, liquidation or reorganization to exercise such
Optionee's option in whole or in part whether or not the vesting requirements
set forth in the option agreement have been satisfied.

                  7.1.2      Conversion of Options on Stock for Stock Exchange

         If the shareholders of the Company receive capital stock of another
corporation ("Exchange Stock") in exchange for their shares of Common Stock in
any transaction involving a merger (other than a merger of the Company in which
the holders of Common Stock immediately prior to the merger have the same
proportionate ownership of Common Stock in the surviving corporation immediately
after the merger), consolidation, acquisition of property or stock, liquidation
or reorganization (other than a mere reincorporation or the creation of a
holding company), the Company and the corporation issuing the Exchange Stock, in
their sole discretion, may determine that all options granted hereunder shall be
converted into options to purchase shares of Exchange Stock instead of
terminating in accordance with the provisions of subsection 7.1.1. The amount
and price of converted options shall be determined by adjusting the amount and
price of the options granted hereunder in the same proportion as used for
determining the number of shares of Exchange Stock the holders of the Common
Stock receive in such merger, consolidation, acquisition of property or stock,
liquidation or reorganization. Unless accelerated by the Board, the vesting
schedule set forth in the option agreement shall continue to apply to the
options granted for the Exchange Stock.

<PAGE>

         7.2      Fractional Shares

         In the event of any adjustment in the number of shares covered by any
option, any fractional shares resulting from such adjustment shall be
disregarded and each such option shall cover only the number of full shares
resulting from such adjustment.

         7.3      Determination of Board to Be Final

         All Section 7 adjustments shall be made by the Plan Administrator, and
its determination as to what adjustments shall be made, and the extent thereof,
shall be final, binding and conclusive. Unless an Optionee agrees otherwise, any
change or adjustment to an incentive stock option shall be made in such a manner
so as not to constitute a "modification" as defined in Section 424(h) of the
Code and so as not to cause his or her incentive stock option issued hereunder
to fail to continue to qualify as an incentive stock option as defined in
Section 422(b) of the Code.

Section 8.  Securities Regulation

         Shares shall not be issued with respect to an option granted under this
Plan unless the exercise of such option and the issuance and delivery of such
shares pursuant thereto shall comply with all relevant provisions of law,
including, without limitation, any applicable state securities laws, the
Securities Act of 1933, as amended, the Exchange Act, the rules and regulations
promulgated thereunder, and the requirements of any stock exchange upon which
the shares may then be listed, and shall be further subject to the approval of
counsel for the Company with respect to such compliance, including the
availability, if applicable of an exemption from registration for the issuance
and sale of any shares hereunder.

Section 9.  Amendment and Termination

         9.1      Board Action

         The Board may at any time suspend, amend or terminate this Plan,
provided that except as set forth in Section 7, and to the extent required for
compliance with Section 422 of the Code or Section 162(m) of the Code or by any
applicable law or requirement, the Company's shareholders must approve within 12
months of the adoption by the Board any amendment which will:

                  (a)   increase the total number of shares that may be issued
                        under this Plan;

                  (b)   modify the class of participants eligible for
                        participation in this Plan; or

                  (c)   otherwise require stockholder approval under any
                        applicable law or regulation.

         Any amendment made to this Plan since its original adoption which would
constitute a "modification" to incentive stock options outstanding on the date
of such amendment, shall not be applicable to such outstanding incentive stock
options, but shall have prospective effect only, unless the Optionee agrees
otherwise.

<PAGE>

         9.2      Automatic Termination

         Unless sooner terminated by the Board, this Plan shall terminate ten
years from the earlier of (a) the date on which this Plan is adopted by the
Board or (b) the date on which this Plan is approved by the shareholders of the
Company. No option may be granted after such termination or during any
suspension of this Plan. The amendment or termination of this Plan shall not,
without the consent of the Optionee, impair or diminish any rights or
obligations under any option theretofore granted under this Plan.

Section 10. Effectiveness of This Plan This

         This Plan shall become effective upon adoption by the Board so long as
it is approved by a majority of stock represented by shareholders voting either
in person or by proxy at a duly held shareholders' meeting any time within 12
months before or after the adoption of this Plan.

Plan adopted by the Board of Directors on March 11, 1993 and approved by the
sole stockholder on March 11, 1993. Ratified by Board of Directors on June 1,
1993. Amended on July 14, 1993. Amendment and Restatement to increase number of
shares issuable approved by the Board of Directors on February 2, 1995 and by
stockholders on April 26, 1995. Amended and Restated by Board of Directors on
February 13, 1997. Amended and Restated by Board of Directors on April 25, 2000.<PAGE>

                                                                   Exhibit 10.15

                                    ADDENDUM
                                     TO THE
                               IMMUNEX CORPORATION
                             1993 STOCK OPTION PLAN

                   (As Amended and Restated on April 25, 2000)

               WHEREAS, Immunex Corporation (hereinafter referred to as the
"Company") maintains the Immunex Corporation 1993 Stock Option Plan (hereinafter
referred to as the "Plan"); and

               WHEREAS, the Company desires to adjoin an addendum (this
"Addendum") to the Plan to address the effects of the transactions contemplated
by the Agreement and Plan of Merger by and between Amgen Inc., AMS Acquisition
Inc. and the Company dated as of December 16, 2001 (the "Merger Agreement");

               NOW, THEREFORE, notwithstanding anything in the Plan to the
contrary, this Addendum is hereby adopted, effective as of the Effective Time
(as defined in the Merger Agreement):

         Section 1. At the Effective Time, each
option granted pursuant the Plan shall be treated in accordance with the
applicable terms of the Merger Agreement.

         Section 2. In the event that an optionee's employment with the Company
or Amgen Inc. is terminated by the optionee for Good Reason or by the Company or
Amgen Inc. without Cause during the fifteen (15) months following the Effective
Time, each option held by such optionee for common stock of Amgen Inc. that was
granted pursuant to the Merger Agreement with respect to (a) a Cancelled Company
Option (as defined in the Merger Agreement) or (b) an option for common stock of
the Company that was granted after December 16, 2001, shall immediately vest in
full and shall remain exercisable until the earlier of (x) the first anniversary
of the optionee's termination of employment or (y) the end of the term of such
option.

         Section 3. For purposes of this Addendum only, "Good Reason" shall mean
the occurrence on or after the Effective Date and without the optionee's consent
of, (a) a reduction in the optionee's annual base salary or wages, other than as
part of a general reduction applicable to substantially all employees of the
Company employed in the United States or (ii) the relocation of the optionee's
principal place of employment to a location more than fifty (50) miles from the
optionee's principal place of employment prior to the Effective Date.

         Section 4. For purposes of this Addendum only, "Cause" shall mean (a)
the willful and continued failure by the optionee to substantially perform the
optionee's duties with the Company (other than such failure resulting form the
optionee's incapacity due to physical or mental illness) or (b) the willful
engaging by the optionee in conduct which is demonstratably and materially
injurious to the Company, monetarily or otherwise. For purposes of this
definition, no act, or failure to act, on the optionee's part shall be deemed
willful unless done, or omitted to be done, by the optionee not in good faith or
without reasonable belief that the optionee's act, or failure to act, was in the
best interest of the Company.

         Section 5. This Addendum shall be effective only upon the Effective
Time. In the event that the Merger Agreement terminates according to its terms,
this Addendum shall be of no force or effect.

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