Document:

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                                                                    Exhibit 10.3

                         AMGEN INC. AMENDED AND RESTATED
                        1999 EMPLOYEE STOCK PURCHASE PLAN

SECTION 1.   PURPOSE

     The purposes of the Amgen Inc. Amended and Restated 1999 Employee Stock
Purchase Plan (the "Plan") are (a) to assist employees of Immunex Corporation, a
Washington corporation ("Immunex"), and its designated subsidiaries in acquiring
a stock ownership interest in Amgen Inc., a Delaware corporation and parent
corporation of Immunex (the "Company"), pursuant to a plan that is intended to
qualify as an "employee stock purchase plan" under Section 423 of the Internal
Revenue Code of 1986, as amended, and (b) to encourage employees to remain in
the employ of Immunex and its subsidiaries. This Plan amends and restates in its
entirety the Immunex Corporation 1999 Employee Stock Purchase Plan, as amended
and restated.

SECTION 2.   DEFINITIONS

     For purposes of the Plan, the following terms shall be defined as set forth
below.

     "Board" means the Board of Directors of the Company.

     "Code" means the Internal Revenue Code of 1986, as amended.

     "Committee" means the Compensation Committee of the Board.

     "Common Stock" means the common stock, par value $0.0001 per share, of the
Company.

     "Company" has the meaning set forth in Section 1.

     "Designated Subsidiary" has the meaning set forth under the definition of
"Eligible Employee" in this Section 2.

     "Eligible Compensation" means all salary and wages including overtime.
Regular cash compensation does not include cash bonuses, commissions, severance
pay, hiring and relocation bonuses, pay in lieu of vacations, sick leave, gain
from stock option exercises or any other special payments.

     "Eligible Employee" means any employee of Immunex or any domestic
Subsidiary Corporation or any other Subsidiary Corporation designated by the
Board or the Committee (each a "Designated Subsidiary"), who is in the employ of
Immunex (or any Designated Subsidiary) on one or more Offering Dates and who
meets the following criteria:

             (a) the employee does not, immediately after the option is granted,
own stock (as defined by the Code) possessing 5% or more of the total combined
voting power or value of all classes of stock of Immunex or of a Parent
Corporation or Subsidiary Corporation of Immunex;

             (b) the employee's customary employment is for 20 hours or more per
week; provided, however, that the Plan Administrator may increase or decrease
this minimum requirement for any future Offering so long as the maximum number
of hours does not exceed 20 hours;

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             (c) if specified by the Plan Administrator for future Offerings,
minimum requirements for customary employment of a maximum of five months per
year;

             (d) the employee has been employed for at least three months as of
the Offering Date; provided, however, if specified by the Plan Administrator for
any future Offering, a minimum employment period that does not exceed two years;
and

             (e) the employee is not a highly compensated employee. For purposes
of the Plan, a "highly compensated employee" is any employee of Immunex or a
Designated Subsidiary who has a base salary in excess of $175,000 per year;
provided, however, that the Plan Administrator may increase or decrease this
amount for any future Offering within the limitations imposed by Code Section
423.

If the Company permits any employee of a Designated Subsidiary to participate in
the Plan, then all employees of that Designated Subsidiary who meet the
requirements of this paragraph shall also be considered Eligible Employees.

     "Enrollment Period" has the meaning set forth in Section 7.1.

     "ESPP Broker" has the meaning set forth in Section 10.

     "ESPP Conversion Ratio" has the meaning set forth in Section 6.3.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended.

     "Immunex" has the meaning set forth in Section 1.

     "Immunex Common Stock" means the common stock, par value $.01 per share, of
Immunex.

     "Merger Agreement" means the Amended and Restated Agreement and Plan of
Merger, by and between Amgen Inc., AMS Acquisition Inc. and Immunex Corporation,
dated as of December 16, 2001, as amended by that certain First Amendment to
Amended and Restated Agreement and Plan of Merger dated as of July 15, 2002.

     "Offering" has the meaning set forth in Section 5.1.

     "Offering Date" means the first day of an Offering.

     "Option" means an option granted under the Plan to an Eligible Employee to
purchase shares of Common Stock.

     "Parent Corporation" means any corporation, other than Immunex, in an
unbroken chain of corporations ending with Immunex, if, at the time of the
granting of the Option, each of the corporations, other than Immunex, 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.

     "Participant" means any Eligible Employee who has elected to participate in
an Offering in accordance with the procedures set forth in Section 7.1 and who
has not withdrawn from the Plan or whose participation in the Plan is not
terminated.

     "Plan" has the meaning set forth in Section 1.

     "Plan Administrator" has the meaning set forth in Section 3.1.

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     "Purchase Date" means the last day of each Purchase Period.

     "Purchase Period" has the meaning set forth in Section 5.2.

     "Purchase Price" has the meaning set forth in Section 6.

     "Subscription" has the meaning set forth in Section 7.1.

     "Subsidiary Corporation" means any corporation, other than Immunex, in an
unbroken chain of corporations beginning with Immunex, if, at the time of the
granting of the Option, each of the corporations, other than the last
corporation in the unbroken chain, 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.

SECTION 3.   ADMINISTRATION

     3.1     Plan Administrator

     The Plan shall be administered by the Board or the Committee or, if and to
the extent the Board or the Committee designates an executive officer of the
Company to administer the Plan, by such executive officer (each, the "Plan
Administrator"). Any decisions made by the Plan Administrator shall be
applicable equally to all Eligible Employees.

     3.2     Administration and Interpretation by the Plan Administrator

     Subject to the provisions of the Plan, the Plan Administrator shall have
the authority, in its sole discretion, to determine all matters relating to
Options granted under the Plan, including all terms, conditions, restrictions
and limitations of Options; provided, however, that all Participants granted
Options pursuant to the Plan shall have the same rights and privileges within
the meaning of Code Section 423. The Plan Administrator shall also have
exclusive authority to interpret the Plan and may from time to time adopt, and
change, rules and regulations of general application for the Plan's
administration. The Plan Administrator's interpretation of the Plan and its
rules and regulations, and all actions taken and determinations made by the Plan
Administrator pursuant to the Plan, unless reserved to the Board or the
Committee, shall be conclusive and binding on all parties involved or affected.
The Plan Administrator may delegate administrative duties to such of the
Company's other officers or employees as the Plan Administrator so determines.

SECTION 4.   STOCK SUBJECT TO PLAN

     Subject to adjustment from time to time as provided in Section 20, the
maximum number of shares of Common Stock which shall be available for issuance
under the Plan shall be 1,297,405/1/ shares. Shares issued under the Plan shall
be drawn from authorized and unissued shares or shares now held or subsequently
acquired by the Company.

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/1/ The original number of shares of Immunex Common Stock in the Plan was
500,000. This was adjusted to 3,000,000 as a result of a 2-for-1 stock split on
August 26, 1999 and a split March 20, 2000. This number was subsequently
adjusted to reflect the conversion of the shares of Immunex Common Stock that
remained available for issuance under the Plan as of the Effective Time (as
defined in the Merger Agreement) into shares of Common Stock in a manner
intended to comply with Section 424(a) of the Code.

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SECTION 5.  OFFERING DATES

      5.1   Offerings

      (a)       Except as otherwise set forth below, the Plan shall be
implemented by a series of Offerings (each, an "Offering"). Offerings shall
commence on May 1 and November 1 of each year and end on the next October 31 and
April 30, respectively, occurring thereafter (each, an "Offering").

      (b)       Notwithstanding the foregoing, the Plan Administrator may
establish (i) a different term for one or more Offerings and (ii) different
commencing and ending dates for such Offerings; provided, however, that an
Offering may not exceed five years; and provided, further, that if the Purchase
Price may be less than 85% of the fair market value of the Common Stock on the
Purchase Date, the Offering may not exceed one year.

      (c)       In the event the first or the last day of an Offering is not a
regular business day, then the first day of the Offering shall be deemed to be
the next regular business day and the last day of the Offering shall be deemed
to be the last preceding regular business day.

      5.2   Purchase Periods

            (a) Each Offering shall consist of one or more consecutive purchase
periods (each, a "Purchase Period"). The last day of each Purchase Period shall
be the Purchase Date for such Purchase Period. Each Purchase Period shall
commence on May 1 and November 1 of each year and end on the next October 31 and
April 30, respectively, occurring thereafter.

            (b) Notwithstanding the foregoing, the Board may establish (i) a
different term for one or more Purchase Periods and (ii) different commencing
and ending dates for any such Purchase Period.

            (c) In the event the first or last day of a Purchase Period is not a
regular business day, then the first day of the Purchase Period shall be deemed
to be the next regular business day and the last day of the Purchase Period
shall be deemed to be the last preceding regular business day.

      5.3   Governmental Approval; Stockholder Approval

     Notwithstanding any other provision of the Plan to the contrary, an Option
granted pursuant to the Plan shall be subject to (a) obtaining all necessary
governmental approvals and qualifications of the Plan and of the issuance of
Options and sale of Common Stock pursuant to the Plan and (b) obtaining
stockholder approval of the Plan.

SECTION 6.  PURCHASE PRICE

      6.1   General Rule

     Subject to Section 6.3, the purchase price at which Common Stock may be
acquired in an Offering pursuant to the exercise of all or any portion of an
Option granted under the Plan (the "Purchase Price") shall be 85% of the lesser
of (a) the fair market

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value of the Common Stock on the Offering Date of such Offering and (b) the fair
market value of the Common Stock on the Purchase Date.

      6.2   Fair Market Value

      The fair market value of the Common Stock on the Offering Date or on the
Purchase Date shall be the closing price for the Common Stock as reported for
such day by the Nasdaq Stock Market, the New York Stock Exchange or other
trading market on which the Company's Common Stock may then be traded (the
"Exchange"). If no sales of the Common Stock were made on the Exchange on such
day, fair market value shall mean the closing price for the Common Stock as
reported for the next preceding day on which sales of the Stock were made on the
Exchange. If the Common Stock is not listed on an Exchange, the Board shall
designate an alternative method of determining the fair market value of the
Common Stock.

      6.3   Purchase Period Ending on October 31, 2002

      Notwithstanding Section 6.1, the Purchase Price with respect to the
Purchase Period commencing on May 1, 2002 and ending on October 31, 2002 shall
be 85% of the lesser of (a) the quotient obtained by dividing (i) the closing
price on May 1, 2002 of a share of Immunex Common Stock as reported by the
Nasdaq Stock Market, by (ii) the ESPP Conversion Ratio (as defined below), and
(b) the fair market value of a share of Common Stock on the Purchase Date. For
purposes of the above calculation, "ESPP Conversion Ratio" shall mean the
quotient obtained by dividing (x) the average of the closing trading prices of a
share of Immunex Common Stock on the Nasdaq Stock Market for the twenty (20)
consecutive trading days ending at 4:00 p.m. New York time on the fifth business
day immediately preceding the Closing Date (as defined in the Merger Agreement)
by (y) the average of the closing trading prices of a share of Common Stock on
the Nasdaq Stock Market for the twenty (20) consecutive trading days ending at
4:00 p.m. New York time on the fifth business day immediately preceding the
Closing Date.

SECTION 7.  PARTICIPATION IN THE PLAN

      7.1   Initial Participation

      An Eligible Employee shall become a Participant on the first Offering Date
after satisfying the eligibility requirements and delivering to the Plan
Administrator during the enrollment period established by the Plan Administrator
(the "Enrollment Period") a subscription (the "Subscription"):

            (a) indicating the Eligible Employee's election to participate in
the Plan;

            (b) authorizing payroll deductions and stating the amount to be
deducted regularly from the Participant's pay; and

            (c) authorizing the purchase of Common Stock for the Participant in
each Purchase Period.

      An Eligible Employee who does not deliver a Subscription as provided above
during the Enrollment Period shall not participate in the Plan for that
Offering, and shall

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not participate in the Plan for any subsequent Offering unless such Eligible
Employee subsequently enrolls in the Plan by delivering a Subscription to the
Plan Administrator during the Enrollment Period for such subsequent Offering.
The Plan Administrator may, from time to time, change the Enrollment Period for
any future Offering as it deems advisable in its sole discretion for the proper
administration of the Plan.

     Except as provided in Section 7.2, an employee who becomes eligible to
participate in the Plan after an Offering has commenced shall not be eligible to
participate in such Offering but may participate in any subsequent Offering,
provided that such employee is still an Eligible Employee as of the commencement
of any such subsequent Offering. Eligible Employees may not participate in more
than one Offering at a time.

     7.2  Alternative Initial Participation

     Notwithstanding any other provisions of the Plan, the Board or the
Committee may provide for any future Offering that any employee of Immunex or
any Designated Subsidiary who first meets the requirements of subparagraphs (a)
through (c) of the paragraph "Eligible Employee" in Section 2 during the course
of an Offering shall, on a date or dates specified in the Offering which
coincides with the day on which such person first meets such requirements or
occurs on a specified date thereafter, receive an Option under that Offering
which Option shall thereafter be deemed to be a part of that Offering. Such
Option shall have the same characteristics as any Options originally granted
under that Offering, except that:

     (i)  the date on which such Option is granted shall be the "Offering Date"
          of such Option for all purposes, including determining the Purchase
          Price of such Option; provided, however, that if the fair market value
          of the Common Stock on the date on which such Option is granted is
          less than the fair market value of Common Stock on the first day of
          the Offering, then, solely for the purpose of determining the Purchase
          Price of such Option, the first day of the Offering shall be the
          "Offering Date" for such Option;

     (ii) the Purchase Period(s) for such Option shall begin on its Offering
          Date and end coincident with the remaining Purchase Date(s) for such
          Offering; and

     (c)  the Board or the Committee may provide that if such person first meets
          such requirements within a specified period of time before the end of
          a Purchase Period for such Offering, he or she will not receive any
          Option for that Purchase Period.

     7.3  Continued Participation

     A Participant shall automatically participate in the next Offering until
such time as such Participant withdraws from the Plan pursuant to Section 11.1
or 11.2 or terminates employment as provided in Section 12.

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SECTION 8. LIMITATIONS ON RIGHT TO PURCHASE SHARES

     8.1  Number of Shares Purchased

     Subject to Section 8.3, the maximum number of shares of stock that may be
offered to a Participant on any Offering Date shall be equal to $15,000 divided
by the fair market value of one share of Common Stock on the applicable Offering
Date. Further, no Participant shall be entitled to purchase Common Stock under
the Plan (or any other employee stock purchase plan that is intended to meet the
requirements of Code Section 423 sponsored by the Company, Immunex, a Parent
Corporation or a Subsidiary Corporation) with a fair market value exceeding
$15,000, determined as of the Offering Date for each Offering (or such other
limit as may be imposed by the Code), in any calendar year in which a
Participant participates in the Plan (or other employee stock purchase plan
described in this Section 8.1). For any future Offering, the Board or the
Committee may specify a maximum number of shares which may be purchased by any
Participant as well as a maximum aggregate number of shares which may be
purchased by all Participants pursuant to such Offering. In addition, for any
future Offering with more than one Purchase Date, the Board or the Committee may
specify a maximum aggregate number of shares which may be purchased by all
Participants on any given Purchase Date under the Offering.

     8.2  Pro Rata Allocation

     In the event the number of shares of Common Stock that might be purchased
by all Participants in the Plan exceeds the number of shares of Common Stock
available in the Plan, the Plan Administrator shall make a pro rata allocation
of the remaining shares of Common Stock in as uniform a manner as shall be
practicable and as the Plan Administrator shall determine to be equitable.
Fractional shares may not be issued under the Plan unless the Plan Administrator
determines otherwise for any future Offering.

     8.3  Purchase Period Ending on October 31, 2002

     Notwithstanding the first sentence of Section 8.1, the maximum number of
shares of Common Stock that may be offered to any Participant with respect to
the Purchase Period commencing on May 1, 2002 and ending on October 31, 2002
shall be equal to $15,000, divided by the following quotient: (a) the closing
price on May 1, 2002 of a share of Immunex Common Stock as reported by the
Nasdaq Stock Market, divided by (b) the ESPP Conversion Ratio.

SECTION 9. PAYMENT OF PURCHASE PRICE

     9.1  General Rules

     Subject to Section 9.12, Common Stock that is acquired pursuant to the
exercise of all or any portion of an Option may be paid for only by means of
payroll deductions from the Participant's Eligible Compensation. Except as set
forth in this Section 9, the amount of compensation to be withheld from a
Participant's Eligible Compensation during each pay period shall be determined
by the Participant's Subscription.

     9.2  Changes in Withholding

     Unless otherwise determined by the Plan Administrator for any future
Offering, a Participant may not elect to increase or decrease the amount to be
withheld from his or

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her Eligible Compensation for an Offering; provided, however, that if such
elections are permitted for any future Offering, notice of such elections must
be delivered to the Plan Administrator in such form and in accordance with such
terms as the Plan Administrator may establish for the Offering.

     9.3   Percent Withheld

     The amount of payroll withholding for each Participant for purchases
pursuant to the Plan during any pay period shall be at least 1% but shall not
exceed 15% of the Participant's Eligible Compensation for such pay period, but
in no event shall exceed $15,000 per calendar year. Amounts shall be withheld in
whole percentages only.

     9.4   Payroll Deductions

     Payroll deductions shall commence on the first payday following the
Offering Date and shall continue through the last payday of the Offering unless
sooner altered or terminated as provided in the Plan.

     9.5   Memorandum Accounts

     Individual accounts shall be maintained for each Participant for memorandum
purposes only. All payroll deductions from a Participant's compensation shall be
credited to such account but shall be deposited with the general funds of the
Company. All payroll deductions received or held by Immunex or the Company may
be used by Immunex or the Company for any corporate purpose.

     9.6   No Interest

     No interest shall be paid on payroll deductions received or held by Immunex
or the Company.

     9.7   Acquisition of Common Stock

     On each Purchase Date of an Offering, each Participant shall automatically
acquire, pursuant to the exercise of the Participant's Option, the number of
shares of Common Stock arrived at by dividing the total amount of the
Participant's accumulated payroll deductions for the Purchase Period by the
Purchase Price; provided, however, that the number of shares of Common Stock
purchased by the Participant shall not exceed the number of whole shares of
Common Stock so determined, unless the Plan Administrator has determined for any
future Offering that fractional shares may be issued under the Plan; and
provided, further, that the number of shares of Common Stock purchased by the
Participant shall not exceed the number of shares for which Options have been
granted to the Participant pursuant to Section 8.1.

     9.8   Refund of Excess Amounts

     Any cash balance remaining in the Participant's account at the termination
of each Purchase Period shall be refunded to the Participant as soon as
practical after the Purchase Date without the payment of any interest; provided,
however, that if the Participant participates in the next Purchase Period, any
cash balance remaining in the Participant's account shall be applied to the
purchase of Common Stock in the new Purchase Period, provided such purchase
complies with Section 8.1.

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     9.9    Withholding Obligations

     At the time the Option is exercised, in whole or in part, or at the time
some or all of the Common Stock is disposed of, the Participant shall make
adequate provision for federal and state withholding obligations of Immunex or
the Company, if any, that arise upon exercise of the Option or upon disposition
of the Common Stock. Immunex or the Company may withhold from the Participant's
compensation the amount necessary to meet such withholding obligations.

     9.10   Termination of Participation

     No Common Stock shall be purchased on behalf of a Participant on a Purchase
Date if his or her participation in the Offering or the Plan has terminated on
or before such Purchase Date.

     9.11   Procedural Matters

     The Company may, from time to time, establish (a) limitations on the
frequency and/or number of any permitted changes in the amount withheld during
an Offering, as set forth in Section 9.2, (b) an exchange ratio applicable to
amounts withheld in a currency other than U.S. dollars, (c) payroll withholding
in excess of the amount designated by a Participant in order to adjust for
delays or mistakes in the Company's processing of properly completed withholding
elections and (d) such other limitations or procedures as deemed advisable by
the Company in the Company's sole discretion that are consistent with the Plan
and in accordance with the requirements of Code Section 423.

     9.12   Leaves of Absence

     During leaves of absence approved by the Company (or by Immunex previous to
the Closing Date (as defined in the Merger Agreement)) and meeting the
requirements of the applicable Treasury Regulations promulgated under the Code,
a Participant may elect to continue participation in the Plan by delivering cash
payments to the Plan Administrator on the Participant's normal paydays equal to
the amount of his or her payroll deduction under the Plan had the Participant
not taken a leave of absence. Currently, the Treasury Regulations provide that a
Participant may continue participation in the Plan only during the first 90 days
of a leave of absence unless the Participant's reemployment rights are
guaranteed by statute or contract.

SECTION 10. COMMON STOCK PURCHASED UNDER THE PLAN

     10.1   ESPP Broker

     If the Plan Administrator designates or approves a stock brokerage or other
financial services firm (the "ESPP Broker") to hold shares purchased under the
Plan for the accounts of Participants, the following procedures shall apply.
Promptly following each Purchase Date, the number of shares of Common Stock
purchased by each Participant shall be deposited into an account established in
the Participant's name with the ESPP Broker. Each Participant shall be the
beneficial owner of the Common Stock purchased under the Plan and shall have all
rights of beneficial ownership in such Common Stock. A Participant shall be free
to undertake a disposition of the shares of Common Stock in his or her account
at any time, but, in the absence of such a

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disposition, the shares of Common Stock must remain in the Participant's account
at the ESPP Broker until the holding period set forth in Code Section 423 has
been satisfied. With respect to shares of Common Stock for which the holding
period set forth above has been satisfied, the Participant may move those shares
of Common Stock to another brokerage account of the Participant's choosing or
request that a stock certificate be issued and delivered to him or her.
Dividends paid in the form of shares of Common Stock with respect to Common
Stock in a Participant's account shall be credited to such account. A
Participant who is not subject to payment of U.S. income taxes may move his or
her shares of Common Stock to another brokerage account of his or her choosing
or request that a stock certificate be delivered to him or her at any time,
without regard to the Code Section 423 holding period.

         10.2  Notice of Disposition

         By entering the Plan, each Participant agrees to promptly give the
Company notice of any Common Stock disposed of within the later of one year from
the Purchase Date and two years from the Offering Date for such Common Stock,
showing the number of such shares disposed of and the Purchase Date and Offering
Date for such Common Stock. This notice shall not be required if and so long as
the Company has a designated ESPP Broker.

SECTION 11.    VOLUNTARY WITHDRAWAL

         11.1  Withdrawal From an Offering

         A Participant may withdraw from an Offering by signing and delivering
to the Plan Administrator a written notice of withdrawal on a form provided by
the Plan Administrator for such purpose. Such withdrawal must be elected at
least 10 days prior to the end of the Purchase Period for which such withdrawal
is to be effective or by any other date specified by the Plan Administrator for
any future Offering. If a Participant withdraws after the Purchase Date for a
Purchase Period of an Offering, the withdrawal shall not affect Common Stock
acquired by the Participant in any earlier Purchase Periods. Unless otherwise
indicated, withdrawal from an Offering shall not result in a withdrawal from the
Plan or any succeeding Offering therein. A Participant is prohibited from again
participating in the same Offering at any time upon withdrawal from such
Offering. The Company may, from time to time, impose a requirement that the
notice of withdrawal be on file with the Plan Administrator for a reasonable
period prior to the effectiveness of the Participant's withdrawal.

         11.2  Withdrawal From the Plan

         A Participant may withdraw from the Plan by signing a written notice of
withdrawal on a form provided by the Plan Administrator for such purpose and
delivering such notice to the Plan Administrator. Such notice must be delivered
at least 10 days prior to the end of the Purchase Period for which such
withdrawal is to be effective or by any other date specified by the Plan
Administrator for any future Offering. In the event a Participant voluntarily
elects to withdraw from the Plan, the Participant may not resume participation
in the Plan during the same Offering, but may participate in any subsequent
Offering under the Plan by again satisfying the definition of Eligible Employee.
The Company may impose, from time to time, a requirement that the notice of
withdrawal be

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on file with the Plan Administrator for a reasonable period prior to the
effectiveness of the Participant's withdrawal.

         11.3  Return of Payroll Deductions

         Upon withdrawal from an Offering pursuant to Section 11.1 or from the
Plan pursuant to Section 11.2, the withdrawing Participant's accumulated payroll
deductions that have not been applied to the purchase of Common Stock shall be
returned as soon as practical after the withdrawal, without the payment of any
interest, to the Participant and the Participant's interest in the Offering
shall terminate. Such accumulated payroll deductions may not be applied to any
other Offering under the Plan.

SECTION 12.    TERMINATION OF EMPLOYMENT

         Termination of a Participant's employment with Immunex or a Designated
Subsidiary or the Company for any reason, including retirement, death or any
other failure of a Participant to remain an employee of Immunex or a Designated
Subsidiary or the Company, shall immediately terminate the Participant's
participation in the Plan. The payroll deductions credited to the Participant's
account since the last Purchase Date shall, as soon as practical, be returned to
the Participant or, in the case of a Participant's death, to the Participant's
legal representative or designated beneficiary as provided in Section 13.2, and
all of the Participant's rights under the Plan shall terminate. Interest shall
not be paid on sums returned to a Participant pursuant to this Section 12.

SECTION 13.    RESTRICTIONS ON ASSIGNMENT

         13.1  Transferability

         An Option granted under the Plan shall not be transferable and such
Option shall be exercisable during the Participant's lifetime only by the
Participant. The Company will not recognize, and shall be under no duty to
recognize, any assignment or purported assignment by a Participant of the
Participant's interest in the Plan, of his or her Option or of any rights under
his or her Option.

         13.2  Beneficiary Designation

         The Plan Administrator may permit a Participant to designate a
beneficiary who is to receive any shares and cash, if any, from the
Participant's account under the Plan in the event the Participant dies after the
Purchase Date for an Offering but prior to delivery to such Participant of such
shares and cash. In addition, the Plan Administrator may permit a Participant to
designate a beneficiary who is to receive any cash from the Participant's
account under the Plan in the event that the Participant dies before the
Purchase Date for an Offering. Such designation may be changed by the
Participant at any time by written notice to the Plan Administrator.

SECTION 14.    NO RIGHTS AS STOCKHOLDER UNTIL SHARES ISSUED

         With respect to shares of Common Stock subject to an Option, a
Participant shall not be deemed to be a stockholder of the Company, and he or
she shall not have any of the rights or privileges of a stockholder. A
Participant shall have the rights and privileges of a stockholder of the Company
when, but not until, a certificate or its equivalent has been issued to the
Participant for the shares following exercise of the Participant's Option.

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SECTION 15. LIMITATIONS ON SALE OF COMMON STOCK PURCHASED UNDER THE PLAN

         The Plan is intended to provide Common Stock for investment and not for
resale. The Company does not, however, intend to restrict or influence any
Participant in the conduct of his or her own affairs. A Participant, therefore,
may sell Common Stock purchased under the Plan at any time he or she chooses,
subject to compliance with any applicable federal and state securities laws. A
Participant assumes the risk of any market fluctuations in the price of the
Common Stock.

SECTION 16. AMENDMENT OF THE PLAN

         The Board may amend the Plan in such respects as it shall deem
advisable; provided, however, that, to the extent required for compliance with
Code Section 423 or any applicable law or regulation, stockholder approval will
be required for any amendment that will (a) increase the total number of shares
as to which Options may be granted under the Plan, (b) modify the class of
employees eligible to receive Options, or (c) otherwise require stockholder
approval under any applicable law or regulation.

SECTION 17. TERMINATION OF THE PLAN

         The Plan shall have no fixed termination date. Notwithstanding the
foregoing, the Board may suspend or terminate the Plan at any time. During any
period of suspension or upon termination of the Plan, no Options shall be
granted; provided, however, that suspension or termination of the Plan shall
have no effect on Options granted prior thereto.

SECTION 18. NO RIGHTS AS AN EMPLOYEE

         Nothing in the Plan shall be construed to give any person (including
any Eligible Employee or Participant) the right to remain in the employ of
Immunex or any of its affiliates or to affect the right of Immunex or any of its
affiliates to terminate the employment of any person (including any Eligible
Employee or Participant) at any time with or without cause.

SECTION 19. EFFECT UPON OTHER PLANS

         The adoption of the Plan shall not affect any other compensation or
incentive plans in effect for Immunex or any of its affiliates. Nothing in this
Plan shall be construed to limit the right of Immunex or any of its affiliates
to (a) establish any other forms of incentives or compensation for employees of
Immunex or any of its affiliates or (b) grant or assume options otherwise than
under this Plan in connection with any proper corporate purpose, including, but
not by way of limitation, the grant or assumption of options in connection with
the acquisition, by purchase, lease, merger, consolidation or otherwise, of the
business, stock or assets of any corporation, firm or association.

SECTION 20. ADJUSTMENTS

         20.1 Adjustment of Shares

         In the event that, at any time or from time to time, a stock dividend,
stock split (but not including the stock dividend approved by the board of
directors of Immunex on February 23, 1999), spin-off, combination or exchange of
shares, recapitalization,

                                       12

<PAGE>

merger, consolidation, distribution to stockholders other than a normal cash
dividend, or other change in the Company's corporate or capital structure
results in (a) the outstanding shares, or any securities exchanged therefor or
received in their place, being exchanged for a different number or kind of
securities of the Company or of any other corporation or (b) new, different or
additional securities of the Company or of any other corporation being received
by the holders of shares of Common Stock, then (subject to any required action
by the Company's stockholders), the Board or the Committee, in its sole
discretion, shall make such equitable adjustments as it shall deem appropriate
in the circumstances in (i) the maximum number and kind of shares of Common
Stock subject to the Plan as set forth in Section 4 and (ii) the number and kind
of securities that are subject to any outstanding Option and the per share price
of such securities. The determination by the Board or the Committee as to the
terms of any of the foregoing adjustments shall be conclusive and binding.
Notwithstanding the foregoing, a dissolution, liquidation, merger or asset sale
of the Company shall not be governed by this Section 20.1 but shall be governed
by Sections 20.2 and 20.3, respectively.

         20.2 Merger or Asset Sale of Immunex or the Company

         In the event of a proposed sale of all or substantially all of the
assets of Immunex or the Company, or the merger of Immunex or the Company with
or into another corporation (but not including any internal corporate
restructuring or reorganization involving Immunex and the Company), each
outstanding Option shall be assumed or an equivalent option substituted by the
successor corporation or a parent or subsidiary corporation of the successor
corporation. In the event that the successor corporation refuses to assume or
substitute for the Option, the Offering then in progress shall be shortened by
setting a new Purchase Date. The new Purchase Date shall be a specified date
before the date of the proposed sale or merger of Immunex or the Company. The
Board shall notify each Participant in writing, at least 10 business days prior
to the new Purchase Date, that the Purchase Date for the Participant's Option
has been changed to the new Purchase Date and that the Participant's Option
shall be exercised automatically on the new Purchase Date, unless prior to such
date the Participant has withdrawn from the Offering or the Plan as provided in
Section 11 hereof.

         20.3 Dissolution or Liquidation of Immunex or the Company

         In the event of the proposed dissolution or liquidation of Immunex or
the Company (but not including any internal corporate restructuring or
reorganization involving Immunex and the Company), the Offering then in progress
shall be shortened by setting a new Purchase Date and shall terminate
immediately prior to the consummation of such proposed dissolution or
liquidation, unless provided otherwise by the Board. The new Purchase Date shall
be a specified date before the date of the proposed dissolution or liquidation
of Immunex or the Company. The Board shall notify each Participant in writing,
at least 10 business days prior to the new Purchase Date, that the Purchase Date
for the Participant's Option has been changed to the new Purchase Date and that
the Participant's Option shall be exercised automatically on the new Purchase
Date, unless prior to such date the Participant has withdrawn from the Offering
or the Plan as provided in Section 11 hereof.

                                       13

<PAGE>

         20.4 Limitations

         The grant of Options will in no way affect the Company's right to
adjust, reclassify, reorganize or otherwise change its capital or business
structure or to merge, consolidate, dissolve, liquidate or sell or transfer all
or any part of its business or assets.

SECTION 21. REGISTRATION; CERTIFICATES FOR SHARES

         The Company shall be under no obligation to any Participant to register
for offering or resale under the Securities Act of 1933, as amended, or register
or qualify under state securities laws, any shares of Common Stock. The Company
may issue certificates for shares with such legends and subject to such
restrictions on transfer and stop-transfer instructions as counsel for the
Company deems necessary or desirable for compliance by the Company with federal
and state securities laws.

SECTION 22. EFFECTIVE DATE

         The Plan's effective date is the date on which it was approved by
Immunex's shareholders, which was April 29, 1999. The Plan was amended and
restated by the board of directors of Immunex on April 25, 2000 and was amended
and restated by the Board on July 15, 2002.

                                       14<PAGE>

                                                                    EXHIBIT 10.4

                               IMMUNEX CORPORATION
                   STOCK OPTION PLAN FOR NONEMPLOYEE DIRECTORS
                     Amended and Restated on April 18, 2000

SECTION 1.  PURPOSES

     The purposes of the Immunex Corporation Stock Option Plan for Nonemployee
Directors (this "Plan") are to attract and retain the services of experienced
and knowledgeable nonemployee directors of Immunex Corporation (the "Company")
and to provide an incentive for such directors by providing an opportunity for
stock ownership in the Company.

SECTION 2.  SHARES SUBJECT TO THE PLAN

     Subject to adjustment in accordance with Section 6 hereof, the total number
of shares of the Company's common stock (the "Common Stock") for which options
may be granted under this Plan is 1,200,000/1/ (the "Shares"). The Shares shall
be shares currently authorized but unissued or subsequently acquired by the
Company and shall include shares representing the unexercised portion of any
option granted under this Plan which expires or terminates without being
exercised in full.

SECTION 3.  ADMINISTRATION OF THE PLAN

     The administrator of this Plan (the "Plan Administrator") shall be the
Board of Directors of the Company (the "Board"). Subject to the terms of this
Plan, the Plan Administrator shall have the power to construe the provisions of
this Plan, to determine all questions arising hereunder and to adopt and amend
such rules and regulations for the administration of this Plan as it may deem
desirable.

SECTION 4.  PARTICIPATION IN THE PLAN

     4.1    Eligible Directors

     Each member of the Board elected or appointed who is not otherwise an
employee of the Company, any parent or subsidiary corporation, or a director
appointed by American Cyanamid Company or American Home Products Corporation
pursuant to the Amended and Restated Governance Agreement dated as of December
15, 1992 (an "Eligible Director") shall be eligible to participate in this Plan.

____________
     /1/ The original number of Shares in this Plan was 100,000. This number was
adjusted to 1,200,000 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.

                                                                          Page 1

<PAGE>

     4.2   Initial Grants

     Each Eligible Director who is elected or appointed for the first time after
the date of adoption of this Plan shall automatically receive the grant of an
option to purchase 10,000 Shares on the day such Eligible Director is initially
elected or appointed.

     4.3   Annual Grants

     Each Eligible Director continuing service as an Eligible Director
immediately following an Annual Meeting of Shareholders shall automatically
receive an option to purchase 5,000 Shares immediately following each year's
Annual Meeting of Shareholders as an annual grant; provided, however, that an
Eligible Director who has received an initial grant of an option to purchase
10,000 Shares on such date shall not receive an annual grant until the next
Annual Meeting.

SECTION 5. OPTION TERMS

     Each option granted to an Eligible Director under this Plan and the
issuance of Shares hereunder shall be subject to the following terms:

     5.1   Option Agreement

     Each option granted under this Plan shall be evidenced by an option
agreement (an "Agreement") duly executed on behalf of the Company. Each
Agreement shall comply with and be subject to the terms and conditions of this
Plan. Any Agreement may contain such other terms, provisions and conditions not
inconsistent with this Plan as may be determined by the Plan Administrator.

     5.2   Option Exercise Price

     The option exercise price for an option granted under this Plan shall be
the closing price, or if there is no closing price, the mean between the high
and the low sale price of the Shares covered by the option on the day the option
is granted on the Nasdaq Stock Market or, if no Common Stock was traded on such
date, on the immediately preceding date on which Common Stock was so traded.

     5.3   Vesting and Exercisability

     Each option granted to an Eligible Director shall vest and become
exercisable in accordance with the following schedule:

 Period of Eligible Directors' Continuous
Service as a Director With the Company From     Portion of Total Option Which Is
   the Date the Option is Granted                         Exercisable
---------------------------------------------  ---------------------------------

      Less than twelve months                                 0%

                                                                          Page 2

<PAGE>

            Twelve months                              20%

          Twenty-four months                           40%

          Thirty-six months                            60%

          Forty-eight months                           80%

       Sixty months or greater                        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
Eligible Director's service as a member of the Board on account of the Eligible
Director's death, provided that the Eligible Director has served as a member of
the Board for at least two years at the date of such Eligible Director's death.

     5.4 Time and Manner of Exercise of Option

     Each option may be exercised in whole or in part at any time and from time
to time; provided, however, that no fewer than 100 Shares (or the remaining
Shares then purchasable under the option, if less than 100 Shares) may be
purchased upon any exercise of any option hereunder and that only whole Shares
will be issued pursuant to the exercise of any option.

     Any option may be exercised by giving written notice, signed by the person
exercising the option, to the Company stating the number of Shares with respect
to which the option is being exercised, accompanied by payment in full for such
Shares, which payment may be in whole or in part (a) in cash or by check, (b) in
shares of Common Stock already owned for at least six months by the person
exercising the option, valued at fair market value at the time of such exercise,
or (c) by delivery of a properly executed exercise notice, together with
irrevocable instructions to a broker, to properly deliver to the Company the
amount of sale or loan proceeds to pay the exercise price, all in accordance
with the regulations of the Federal Reserve Board.

     5.5 Term of Options

    Each option shall expire ten years from the date of the granting thereof,
but shall be subject to earlier termination as follows:

          (a)   In the event that an optionee ceases to be a director of the
     Company for any reason other than the death of the optionee the unvested
     portion of the options granted to such optionee shall terminate immediately
     and the vested portion of the options granted to such optionee may be
     exercised by him or her only within three months after the date such
     optionee ceases to be a director of the Company.

          (b)   In the event of the death of an optionee, whether during the
     optionee's service as a director or during the three month period referred
     to in Section 5.5(a), the unvested portion of the options granted to such
     optionee shall terminate immediately and the vested portion of the options
     granted to such optionee shall be exercisable, and such

                                                                          Page 3

<PAGE>

     options shall expire unless exercised within twelve months after the date
     of the optionee's death, by the legal representatives or the estate of such
     optionee, by any person or persons whom the optionee shall have designated
     in writing on forms prescribed by and filed with the Company or, if no such
     designation has been made, by the person or persons to whom the optionee's
     rights have passed by will or the laws of descent and distribution.

     5.6  Transferability

     During an optionee's lifetime, an option may be exercised only by the
optionee. Options granted under this Plan and the rights and privileges
conferred thereby shall not be subject to execution, attachment or similar
process and 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. In addition, the Plan Administrator
may permit a recipient of an option to designate in writing during the
optionee's lifetime a beneficiary to receive and exercise options in the event
of the optionee's death (as provided in Section 5.5(b)). Any attempt to
transfer, assign, pledge, hypothecate or otherwise dispose of any option under
this Plan or of any right or privilege conferred thereby, contrary 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.

     5.7  Holding Period

     If an individual subject to Section 16 of the Exchange Act of 1934, as
amended (the "Exchange Act") sells shares of Common Stock obtained upon the
exercise of any option granted under this Plan 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.

     5.8  Participant's or Successor's Rights as Shareholder

     Neither an optionee nor the optionee's successor(s) in interest shall have
any rights as a shareholder of the Company with respect to any Shares subject to
an option granted to the optionee until such person becomes a holder of record
of such Shares.

     5.9  Limitation as to Directorship

     Neither this Plan, nor the granting of an option, nor any other action
taken pursuant to this Plan shall constitute or be evidence of any agreement or
understanding, express or implied, that an optionee has a right to continue as a
director for any period of time or at any particular rate of compensation.

     5.10 Regulatory Approval and Compliance

     The Company shall not be required to issue any certificate or certificates
for Shares upon the exercise of an option granted under this Plan, or record as
a holder of record of Shares the name of the individual exercising an option
under this Plan, without obtaining to the complete satisfaction of the Plan
Administrator the approval of all regulatory bodies deemed necessary by

                                                                          Page 4

<PAGE>

the Plan Administrator, and without complying, to the Plan Administrator's
complete satisfaction, with all rules and regulations under federal, state or
local law deemed applicable by the Plan Administrator.

SECTION 6. CAPITAL ADJUSTMENTS

     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 stock dividends, stock splits,
recapitalizations, combinations or exchanges of shares, split-ups, split-offs,
spinoffs, or other similar changes in capitalization. Notwithstanding the
foregoing, if an automatic grant occurs within ninety days following any such
change in capitalization, the aggregate number and class of Shares subject to
such automatic grant shall be proportionately adjusted to be the same number and
class of Shares that would be subject to the automatic grant had it been
outstanding immediately prior to the date of such change in capitalization. Upon
the effective date of a dissolution or liquidation of the Company, or of a
reorganization, merger or consolidation of the Company with one or more
corporations that results in more than 70% of the outstanding voting shares of
the Company being owned by one or more affiliated corporations or other
affiliated entities, or of a transfer of all or substantially all the assets or
more than 70% of the then outstanding shares of the Company to another
corporation or other entity, this Plan and all options granted hereunder shall
terminate. In the event of such dissolution, liquidation, reorganization,
merger, consolidation, transfer of assets or transfer of stock, each optionee
shall be entitled, for a period of twenty days prior to the effective date of
such transaction, to purchase the full number of shares under his or her option
which he or she otherwise would have been entitled to purchase during the
remaining term of such option.

     Adjustments under this Section 6 shall be made by the Plan Administrator,
whose determination shall be final. 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.

SECTION 7. EXPENSES OF THE PLAN

     All costs and expenses of the adoption and administration of this Plan
shall be borne by the Company; none of such expenses shall be charged to any
optionee.

SECTION 8. COMPLIANCE WITH RULE 16b-3

     It is the intention of the Company that this Plan comply in all respects
with the requirements for a "formula plan" within the meaning attributed to that
term for purposes of Rule 16b-3 promulgated under Section 16(b) of the Exchange
Act. Therefore, if any Plan provision is later found not to be in compliance
with such requirements, that provision shall be deemed null and void, and in all
events this Plan shall be construed in favor of its meeting such requirements.

                                                                          Page 5

<PAGE>

SECTION 9.   TERMINATION AND AMENDMENT OF THE PLAN

     The Board may amend, terminate or suspend this Plan at any time, in its
sole and absolute discretion; provided, however, that if required to qualify
this Plan as a formula plan for purposes of Rule 16b-3 under Section 16(b) of
the Exchange Act, no amendment may be made more than once every six months that
would change the amount, price, timing or vesting of the options, other than to
comply with changes in the Internal Revenue Code of 1986, as amended, or the
rules and regulations thereunder; provided further that no amendment that would
(a) increase the number of Shares that may be issued under this Plan, or (b)
otherwise require shareholder approval under any applicable law or regulation
shall be made without the approval of the Company's shareholders.

SECTION 10.  DURATION

     This Plan shall continue in effect until December 13, 2003 unless it is
sooner terminated by action of the Board or the Company's shareholders, but such
termination shall not affect the terms of any then-outstanding options. Adopted
by the Company's Board of Directors on December 13, 1993 and approved by the
Company's shareholders on April 27, 1994. Amended and restated by the Board on
February 13, 1997. Amended and restated by the Board on February 23, 1999.
Amended and restated by the Board on April 18, 2000.

                                                                          Page 6

<PAGE>

                                    ADDENDUM
                                     TO THE
                               IMMUNEX CORPORATION
                   STOCK OPTION PLAN FOR NONEMPLOYEE DIRECTORS

     WHEREAS, Immunex Corporation (the "Company") maintains the Stock Option
Plan for Nonemployee Directors (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 ceases to be a director of the
Company or Amgen Inc. for any reason immediately prior to, at, or during the
fifteen (15) months following the Effective Time, each option held by such
optionee for common stock of Amgen Inc. shall immediately vest in full and shall
remain exercisable until the earlier of (x) the first anniversary of the date
such optionee ceases to be a director of the Company or Amgen Inc. or (y) the
end of the term of such option.

     Section 3. 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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