PDL BIOPHARMA, INC. STOCK OPTION AGREEMENT (INCENTIVE)

Exhibit 10.4

PDL BIOPHARMA, INC.

STOCK OPTION AGREEMENT (INCENTIVE)

PDL BioPharma, Inc. has granted to the individual (the “Optionee”) named in the Notice of Grant of Stock Option (the “Notice”) to which this Stock Option Agreement (Incentive) is attached an option (the “Option”) to purchase certain shares of Stock upon the terms and conditions set forth in this Option Agreement (the “Option Agreement”) and the Notice. The Option has been granted pursuant to the Company’s 1999 Stock Option Plan (the “Plan”). By signing the Notice, the Optionee represents that the Optionee is familiar with the terms and provisions of this Option Agreement and accepts the Option subject to all of the terms and provisions hereof. The Optionee agrees to accept as final and binding all decisions or interpretations of the Board upon any questions arising under this Option Agreement or the Plan.

1. DEFINITIONS AND CONSTRUCTION.

1.1 Definitions. Whenever used herein, capitalized terms shall have the meanings assigned in the Notice or as set forth below:

(a) “Board” means the Board of Directors of the Company.

(b) “Code” means the Internal Revenue Code of 1986, as amended, and any applicable regulations promulgated thereunder.

(c) “Company” means PDL BioPharma, Inc., a Delaware corporation, or any successor corporation thereto.

(d) “Consultant” means any Person, including an advisor, engaged by a Participating Company to render services other than as an Employee or a Director.

(e) “Director” means a member of the Board.

(f) “Disability” means the permanent and total disability of the Optionee within the meaning of Section 22(e)(3) of the Code.

(g) “Employee” means any Person treated as an employee (including an officer or a Director who is also treated as an employee) in the records of a Participating Company and who is an employee for purposes of Section 422 of the Code; provided, however, that neither service as a Director nor payment of a director’s fee shall be sufficient to constitute employment for this purpose.

1

(h) “Exchange Act” means the Securities Exchange Act of 1934, as amended.

(i) “Fair Market Value” means, as of any date, the value of a share of Stock or other property as determined by the Board, in its discretion, subject to the following:

(i) If, on such date, the Stock is listed on a national or regional securities exchange or market system, the Fair Market Value of a share of Stock shall be the closing sale price of a share of Stock (or the mean of the closing bid and asked prices of a share of Stock if the Stock is so quoted instead) as quoted on the Nasdaq National Market, The Nasdaq SmallCap Market or such other national or regional securities exchange or market system constituting the primary market for the Stock, as reported in the Wall Street Journal or such other source as the Board deems reliable. If the relevant date does not fall on a day on which the Stock has traded on such securities exchange or market system, the date on which the Fair Market Value shall be established shall be the last day on which the Stock was so traded prior to the relevant date, or such other appropriate day as shall be determined by the Board, in its discretion.

(ii) If, on such date, the Stock is not listed on a national or regional securities exchange or market system, the Fair Market Value of a share of Stock shall be as determined by the Board without regard to any restriction other than a restriction which, by its terms, will never lapse.

(j) “Parent Corporation” means any present or future “parent corporation” of the Company, as defined in Section 424(e) of the Code.

(k) “Participating Company” means the Company or any Parent Corporation or Subsidiary Corporation.

(l) “Participating Company Group” means, at any point in time, all corporations collectively which are then Participating Companies.

(m) “Person” means a natural person.

(n) “Securities Act” means the Securities Act of 1933, as amended.

(o) “Service” means the Optionee’s employment or service with the Participating Company Group, whether in the capacity of an Employee, a Director or a Consultant. Unless otherwise provided by the Board, the Optionee’s Service shall not be deemed to have terminated merely because of a change in the capacity in which the Optionee renders Service to the Participating Company Group or a change in the Participating Company for which the Optionee renders such Service, provided that there is no interruption or termination of the Optionee’s Service. Furthermore, the Optionee’s Service with the Participating Company Group shall not be deemed to have terminated if the Optionee takes any bona fide leave of absence approved by the Company; provided, however, that if any such leave exceeds ninety (90) days, on the one hundred eighty-first (181st) day following the commencement of such leave the

2

Option shall cease to be treated as an incentive stock option and instead shall be treated thereafter as a nonstatutory stock option unless the Optionee’s right to return to Service with the Participating Company Group is guaranteed by statute or contract. Notwithstanding the foregoing, unless otherwise required by law, the Company may provide that an approved leave of absence shall not be treated as Service for purposes of determining the Vested Shares under the Option Agreement. The Optionee’s Service shall be deemed to have terminated either upon an actual termination of Service or upon the corporation for which the Optionee performs Service ceasing to be a Participating Company. Subject to the foregoing, the Company, in its discretion, shall determine whether the Optionee’s Service has terminated and the effective date of such termination.

(p) “Stock” means the common stock of the Company, as adjusted from time to time in accordance with Section 9.

(q) “Subsidiary Corporation” means any present or future “subsidiary corporation” of the Company, as defined in Section 424(f) of the Code.

1.2 Construction. Captions and titles contained herein are for convenience only and shall not affect the meaning or interpretation of any provision of this Option Agreement. Except when otherwise indicated by the context, the singular shall include the plural and the plural shall include the singular. Use of the term “or” is not intended to be exclusive, unless the context clearly requires otherwise.

2. TAX STATUS OF OPTION.

2.1 Tax Status of Option. This Option is intended to be an incentive stock option within the meaning of Section 422(b) of the Code, but the Company does not represent or warrant that this Option qualifies as such. The Optionee should consult with the Optionee’s own tax advisor regarding the tax effects of this Option and the requirements necessary to obtain favorable income tax treatment under Section 422 of the Code, including, but not limited to, holding period requirements. (NOTE TO OPTIONEE: If the Option is exercised more than three (3) months after the date on which you cease to be an Employee (other than by reason of your death or permanent and total disability as defined in Section 22(e)(3) of the Code), the Option will be treated as a nonstatutory stock option and not as an incentive stock option to the extent required by Section 422 of the Code.)

2.2 Fair Market Value Limitation. To the extent that the Option (together with all incentive stock options granted to the Optionee under all stock option plans of the Participating Company Group, including the Plan) becomes exercisable for the first time during any calendar year for shares having a Fair Market Value greater than One Hundred Thousand Dollars ($100,000), the portion of such options which exceeds such amount will be treated as nonstatutory stock options. For purposes of this Section 2.2, options designated as incentive stock options are taken into account in the order in which they were granted, and the Fair Market Value of stock is determined as of the time the option with respect to such stock is granted. If the Code is amended to provide for a different limitation from that set forth in this Section 2.2, such

3

different limitation shall be deemed incorporated herein effective as of the date required or permitted by such amendment to the Code. If the Option is treated as an incentive stock option in part and as a nonstatutory stock option in part by reason of the limitation set forth in this Section 2.2, the Optionee may designate which portion of such Option the Optionee is exercising. In the absence of such designation, the Optionee shall be deemed to have exercised the incentive stock option portion of the Option first. Separate certificates representing each such portion shall be issued upon the exercise of the Option. (NOTE TO OPTIONEE: If the aggregate Exercise Price of the Option (that is, the Exercise Price multiplied by the Number of Option Shares) plus the aggregate exercise price of any other incentive stock options you hold (whether granted pursuant to the Plan or any other stock option plan of the Participating Company Group) is greater than $100,000, you should contact the Chief Financial Officer or Controller of the Company to ascertain whether the entire Option qualifies as an incentive stock option.)

3. ADMINISTRATION.

All questions of interpretation concerning this Option Agreement shall be determined by the Board. All determinations by the Board shall be final and binding upon all Persons having an interest in the Option. The Chief Executive Officer shall have the authority to act on behalf of the Company with respect to any matter, right, obligation, or election which is the responsibility of or which is allocated to the Company herein.

4. EXERCISE OF THE OPTION.

4.1 Right to Exercise. Except as otherwise provided herein, the Option shall be exercisable prior to the termination of the Option (as provided in Section 6) in an amount not to exceed that portion of the Number of Option Shares which have become Vested Shares less the number of shares previously acquired upon exercise of the Option.

4.2 Method of Exercise. Exercise of the Option shall be by written notice to the Company which must state the election to exercise the Option, the number of whole shares of Stock for which the Option is being exercised and such other representations and agreements as to the Optionee’s investment intent with respect to such shares as may be required pursuant to the provisions of this Option Agreement. The written notice must be signed by the Optionee and must be delivered to the Chief Financial Officer, Controller or Stock Administrator of the Company, or other authorized representative of the Participating Company Group, prior to the termination of the Option as set forth in Section 6, accompanied by full payment of the aggregate Exercise Price for the number of shares of Stock being purchased and the tax withholding obligations, if any, as provided in Section 4.4. The Option shall be deemed to be exercised upon receipt by the Company of such written notice, the aggregate Exercise Price, and tax withholding obligations, if any.

4.3 Payment of Exercise Price.

(a) Forms of Consideration Authorized. Except as otherwise provided below, payment of the aggregate Exercise Price for the number of shares of Stock for

4

which the Option is being exercised shall be made (i) in cash or cash equivalent, (ii) by tender to the Company, or attestation to the ownership, of whole shares of Stock owned by the Optionee having a Fair Market Value (as determined by the Board without regard to any restrictions on transferability applicable to such stock by reason of federal or state securities laws or agreements with an underwriter for the Company) not less than the aggregate Exercise Price, (iii) by means of a Cashless Exercise, as defined in Section 4.3(b)(ii), or (iv) by any combination of the foregoing.

(b) Limitations on Forms of Consideration.

(i) Tender of Stock. Notwithstanding the foregoing, the Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock to the extent such tender or attestation would constitute a violation of the provisions of any law, regulation or agreement restricting the redemption of the shares of Stock. The Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock unless such shares either have been owned by the Optionee for more than six (6) months or were not acquired, directly or indirectly, from the Company.

(ii) Cashless Exercise. A “Cashless Exercise” means the assignment in a form acceptable to the Company of the proceeds of a sale or loan with respect to some or all of the shares of Stock acquired upon the exercise of the Option pursuant to a program or procedure approved by the Company (including, without limitation, through an exercise complying with the provisions of Regulation T as promulgated from time to time by the Board of Governors of the Federal Reserve System). The Company reserves, at any and all times, the right, in the Company’s sole and absolute discretion, to decline to approve or terminate any such program or procedure.

4.4 Tax Withholding. At the time the Option is exercised, in whole or in part, or at any time thereafter as requested by the Company, the Optionee hereby authorizes withholding from payroll and any other amounts payable to the Optionee, and otherwise agrees to make adequate provision for (including by means of a Cashless Exercise to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Participating Company Group, if any, which arise in connection with the Option, including, without limitation, obligations arising upon (i) the exercise, in whole or in part, of the Option, (ii) the transfer, in whole or in part, of any shares of Stock acquired upon exercise of the Option, (iii) the operation of any law or regulation providing for the imputation of interest, or (iv) the lapsing of any restriction with respect to any shares of Stock acquired upon exercise of the Option. THE OPTIONEE IS CAUTIONED THAT THE OPTION IS NOT EXERCISABLE UNLESS THE TAX WITHHOLDING OBLIGATIONS OF THE PARTICIPATING COMPANY GROUP ARE SATISFIED. ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED EVEN THOUGH THE OPTION IS VESTED, AND THE COMPANY SHALL HAVE NO OBLIGATION TO ISSUE A CERTIFICATE FOR SUCH SHARES OF STOCK.

5

4.5 Certificate Registration. Except in the event the Exercise Price is paid by means of a Cashless Exercise, the certificate for the shares of Stock as to which the Option is exercised shall be registered in the name of the Optionee, or, if applicable, in the names of the heirs of the Optionee.

4.6 Restrictions on Grant of the Option and Issuance of Shares. The grant of the Option and the issuance of shares of Stock upon exercise of the Option shall be subject to compliance with all applicable requirements of federal, state or foreign law with respect to such securities. The Option may not be exercised if the issuance of shares of Stock upon exercise would constitute a violation of any applicable federal, state or foreign securities laws or other law or regulations or the requirements of any stock exchange or market system upon which the Stock may then be listed. In addition, the Option may not be exercised unless (i) a registration statement under the Securities Act shall at the time of exercise of the Option be in effect with respect to the shares issuable upon exercise of the Option or (ii) in the opinion of legal counsel to the Company, the shares of Stock issuable upon exercise of the Option may be issued in accordance with the terms of an applicable exemption from the registration requirements of the Securities Act. THE OPTIONEE IS CAUTIONED THAT THE OPTION MAY NOT BE EXERCISED UNLESS THE FOREGOING CONDITIONS ARE SATISFIED. ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED EVEN THOUGH THE OPTION IS VESTED. Questions concerning this restriction should be directed to the Legal Department of the Company. The inability of the Company to obtain from any regulatory body having jurisdiction the authority, if any, deemed by the Company’s legal counsel to be necessary to the lawful issuance and sale of any shares of Stock subject to the Option shall relieve the Company of any liability in respect of the failure to issue or sell such shares as to which such requisite authority shall not have been obtained. As a condition to the exercise of the Option, the Company may require the Optionee to satisfy any qualifications that may be necessary or appropriate, to evidence compliance with any applicable law or regulation and to make any representation or warranty with respect thereto as may be requested by the Company.

4.7 Fractional Shares. The Company shall not be required to issue fractional shares of Stock upon the exercise of the Option.

5. NONTRANSFERABILITY OF THE OPTION.

The Option may be exercised during the lifetime of the Optionee only by the Optionee or the Optionee’s guardian or legal representative and may not be assigned or transferred in any manner except by will or by the laws of descent and distribution. Following the death of the Optionee, the Option, to the extent provided in Section 7, may be exercised by the Optionee’s legal representative or by any Person empowered to do so under the deceased Optionee’s will or under the then applicable laws of descent and distribution.

6

6. TERMINATION OF THE OPTION.

The Option shall terminate and may no longer be exercised on the first to occur of (a) the Option Expiration Date, (b) the last date for exercising the Option following termination of the Optionee’s Service as described in Section 7, or (c) a Change in Control to the extent provided in Section 8.

7. EFFECT OF TERMINATION OF SERVICE.

7.1 Option Exercisability.

(a) Disability. If the Optionee’s Service with the Participating Company Group is terminated because of the Disability of the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s guardian or legal representative) at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date.

(b) Death. If the Optionee’s Service with the Participating Company Group is terminated because of the death of the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee’s legal representative or other Person who acquired the right to exercise the Option by reason of the Optionee’s death at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date. The Optionee’s Service shall be deemed to have terminated on account of death if the Optionee dies within three (3) months after the Optionee’s termination of Service.

(c) Termination After a Change In Control. If the Optionee’s Service with the Participating Company Group ceases as a result of Termination After a Change in Control (as defined below), then (i) the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s guardian or legal representative) at any time prior to the expiration of six (6) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date, and (ii) the number of Vested Shares shall be increased by an amount equal to twenty-five percent (25%) of the Number of Option Shares (but in no event to a number in excess of 100% of the Number of Option Shares) effective as of the date on which the Optionee’s Service terminated; provided, however, that if the Optionee is an Employee serving on a part-time basis, such percentage increase in the number of Vested Shares shall be prorated on the basis of the relationship which the Optionee’s part-time Service bears to full-time Service in the same capacity. Notwithstanding the foregoing, if it is determined that the provisions or operation of this Section 7.1(c) would preclude treatment of a Change in Control as a “pooling-of-interests” for accounting purposes and provided further that in the absence of the preceding sentence such Change in Control would be treated as a “pooling-of-interests” for accounting purposes, then this Section 7.1(c) shall be void ab initio, and the vesting and exercisability of the Option shall be determined under any other applicable provision of the Option Agreement.

7

(d) Other Termination of Service. If the Optionee’s Service with the Participating Company Group terminates for any reason, except Disability, death or Termination After a Change in Control, the Option, to the extent unexercised and exercisable by the Optionee on the date on which the Optionee’s Service terminated, may be exercised by the Optionee within three (3) months (or such longer period of time as determined by the Board, in its discretion) after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date.

7.2 Extension if Exercise Prevented by Law. Notwithstanding the foregoing, if the exercise of the Option within the applicable time periods set forth in Section 7.1 is prevented by the provisions of Section 4.6, the Option shall remain exercisable until ninety (90) days after the date the Optionee is notified by the Company that the Option is exercisable, but in any event no later than the Option Expiration Date.

7.3 Extension if Optionee Subject to Section 16(b). Notwithstanding the foregoing, if a sale within the applicable time periods set forth in Section 7.1 of shares acquired upon the exercise of the Option would subject the Optionee to suit under Section 16(b) of the Exchange Act, the Option shall remain exercisable until the earliest to occur of (i) the thirtieth (30th) day following the date on which a sale of such shares by the Optionee would no longer be subject to such suit, (ii) the two hundred tenth (210th) day after the Optionee’s termination of Service, or (iii) the Option Expiration Date.

7.4 Certain Definitions.

(a) “Termination After a Change in Control” shall mean either of the following events occurring within twelve (12) months after a Change in Control:

(i) termination by the Participating Company Group of the Optionee’s Service with the Participating Company Group for any reason other than for Cause (as defined below); or

(ii) the Optionee’s resignation from all capacities in which the Optionee is then rendering Service to the Participating Company Group within a reasonable period of time following the event constituting a Constructive Termination (as defined below).

Notwithstanding any provision herein to the contrary, Termination After a Change in Control shall not include any termination of the Optionee’s Service with the Participating Company Group which (1) is for Cause (as defined below); (2) is a result of the Optionee’s death or disability; (3) is a result of the Optionee’s voluntary termination of Service other than upon a Constructive Termination; or (4) occurs prior to the effectiveness of a Change in Control.

(b) “Cause” shall mean any of the following: (i) the Optionee’s theft, dishonesty, or falsification of any Participating Company documents or records; (ii) the Optionee’s improper use or disclosure of a Participating Company’s confidential or proprietary information; (iii) any action by the Optionee which has a detrimental effect on a Participating

8

Company’s reputation or business; (iv) the Optionee’s failure or inability to perform any reasonable assigned duties after written notice from the Participating Company Group of, and a reasonable opportunity to cure, such failure or inability; (v) any material breach by the Optionee of any employment agreement between the Optionee and the Participating Company Group, which breach is not cured pursuant to the terms of such agreement; or (vi) the Optionee’s conviction (including any plea of guilty or nolo contendere) of any criminal act which impairs the Optionee’s ability to perform his or her duties with the Participating Company Group.

(c) “Constructive Termination” shall mean any one or more of the following:

(i) without the Optionee’s express written consent, the assignment to the Optionee of any duties, or any limitation of the Optionee’s responsibilities, substantially inconsistent with the Optionee’s positions, duties, responsibilities and status with a Participating Company immediately prior to the date of the Change in Control;

(ii) without the Optionee’s express written consent, the relocation of the principal place of the Optionee’s Service to a location that is more than fifty (50) miles from the Optionee’s principal place of Service immediately prior to the date of the Change in Control, or the imposition of travel requirements substantially more demanding of the Optionee than such travel requirements existing immediately prior to the date of the Change in Control;

(iii) any failure by a Participating Company to pay, or any material reduction by a Participating Company of, (1) the Optionee’s base salary in effect immediately prior to the date of the Change in Control, or (2) the Optionee’s bonus compensation, if any, in effect immediately prior to the date of the Change in Control (subject to applicable performance requirements with respect to the actual amount of bonus compensation earned by the Optionee); or

(iv) any failure by a Participating Company to (1) continue to provide the Optionee with the opportunity to participate, on terms no less favorable than those in effect for the benefit of any employee group which customarily includes a Person holding the employment position or a comparable position with the Participating Company then held by the Optionee, in any benefit or compensation plans and programs, including, but not limited to, the Participating Company’s life, disability, health, dental, medical, savings, profit sharing, stock purchase and retirement plans, if any, in which the Optionee was participating immediately prior to the date of the Change in Control, or their equivalent, or (2) provide the Optionee with all other fringe benefits (or their equivalent) from time to time in effect for the benefit of any employee group which customarily includes a Person holding the employment position or a comparable position with the Participating Company then held by the Optionee.

9

8. CHANGE IN CONTROL.

8.1 Definitions.

(a) An “Ownership Change Event” shall be deemed to have occurred if any of the following occurs with respect to the Company: (i) the direct or indirect sale or exchange in a single or series of related transactions by the stockholders of the Company of more than fifty percent (50%) of the voting stock of the Company; (ii) a merger or consolidation in which the Company is a party; (iii) the sale, exchange, or transfer of all or substantially all of the assets of the Company; or (iv) a liquidation or dissolution of the Company.

(b) A “Change in Control” shall mean an Ownership Change Event or a series of related Ownership Change Events (collectively, the “Transaction”) wherein the stockholders of the Company immediately before the Transaction do not retain immediately after the Transaction, in substantially the same proportions as their ownership of shares of the Company’s voting stock immediately before the Transaction, direct or indirect beneficial ownership of more than fifty percent (50%) of the total combined voting power of the outstanding voting stock of the Company or the corporation or corporations to which the assets of the Company were transferred (the “Transferee Corporation(s)”), as the case may be. For purposes of the preceding sentence, indirect beneficial ownership shall include, without limitation, an interest resulting from ownership of the voting stock of one or more corporations which, as a result of the Transaction, own the Company or the Transferee Corporation(s), as the case may be, either directly or through one or more subsidiary corporations. The Board shall have the right to determine whether multiple sales or exchanges of the voting stock of the Company or multiple Ownership Change Events are related, and its determination shall be final and binding.

8.2 Effect of Change in Control on Option. In the event of a Change in Control, the surviving, continuing, successor, or purchasing corporation or parent corporation thereof, as the case may be (the “Acquiring Corporation”), shall either assume the Company’s rights and obligations under the Option or substitute for the Option a substantially equivalent option for the Acquiring Corporation’s stock. In the event the Acquiring Corporation elects not to assume the Company’s rights and obligations under the Option or substitute for the Option in connection with the Change in Control, and provided that the Optionee’s Service has not terminated prior to such date, the number of Vested Shares shall be increased by an amount equal to twenty-five percent (25%) (or, if the Optionee is an Employee serving on a part-time basis, such percentage shall be prorated on the basis of the relationship which the Optionee’s part-time Service bears to full-time Service in the same capacity) of the Number of Option Shares (but in no event to a number in excess of 100% of the Number of Option Shares) effective as of the date ten (10) days prior to the date of the Change in Control. Any exercise of the Option that was permissible solely by reason of this Section 8.2 shall be conditioned upon the consummation of the Change in Control. The Option shall terminate and cease to be outstanding effective as of the date of the Change in Control to the extent that the Option is neither assumed or substituted for by the Acquiring Corporation in connection with the Change in Control nor exercised as of the date of the Change in Control. Notwithstanding the foregoing, if the corporation the stock of

10

which is subject to the Option immediately prior to an Ownership Change Event described in Section 8.1(a)(i) constituting a Change in Control is the surviving or continuing corporation and immediately after such Ownership Change Event less than fifty percent (50%) of the total combined voting power of its voting stock is held by another corporation or by other corporations that are members of an affiliated group within the meaning of Section 1504(a) of the Code without regard to the provisions of Section 1504(b) of the Code, the Option shall not terminate unless the Board otherwise provides in its sole discretion.

8.3 Fair Market Value Limitation. Should the exercisability of this Option be accelerated in connection with a Change in Control in accordance with Section 7.1(d) or 8.2, then to the extent that the aggregate Fair Market Value of the shares of Stock with respect to which the Optionee may exercise the Option for the first time during the calendar year of such acceleration, when added to the aggregate Fair Market Value of the shares of Stock subject to any other options designated as incentive stock options granted to the Optionee under all stock option plans of the Participating Company Group prior to the Date of Option Grant with respect to which such options are exercisable for the first time during the same calendar year, exceeds One Hundred Thousand Dollars ($100,000) (or such other limit, if any, imposed by Section 422 of the Code), the portion of the Option which exceeds such amount shall be treated as a nonstatutory stock option. For purposes of the preceding sentence, options designated as incentive stock options shall be taken into account in the order in which they were granted, and the Fair Market Value of shares of stock shall be determined as of the time the option with respect to such shares is granted.

9. ADJUSTMENTS FOR CHANGES IN CAPITAL STRUCTURE.

In the event of any stock dividend, stock split, reverse stock split, recapitalization, combination, reclassification, or similar change in the capital structure of the Company, appropriate adjustments shall be made in the number, Exercise Price and class of shares of stock subject to the Option. If a majority of the shares which are of the same class as the shares that are subject to the Option are exchanged for, converted into, or otherwise become (whether or not pursuant to an Ownership Change Event) shares of another corporation (the “New Shares”), the Board may unilaterally amend the Option to provide that the Option is exercisable for New Shares. In the event of any such amendment, the Number of Option Shares and the Exercise Price shall be adjusted in a fair and equitable manner, as determined by the Board, in its sole discretion. Notwithstanding the foregoing, any fractional share resulting from an adjustment pursuant to this Section 9 shall be rounded down to the nearest whole number, as determined by the Board, and in no event may the Exercise Price be decreased to an amount less than the par value, if any, of the stock subject to the Option. The adjustments determined by the Board pursuant to this Section 9 shall be final and binding.

10. RIGHTS AS A STOCKHOLDER, EMPLOYEE OR CONSULTANT.

The Optionee shall have no rights as a stockholder with respect to any shares of Stock covered by the Option until the date of the issuance of a certificate for the shares of Stock for which the Option has been exercised (as evidenced by the appropriate entry on the books of

11

the Company or of a duly authorized transfer agent of the Company). No adjustment shall be made for dividends, distributions or other rights for which the record date is prior to the date such certificate is issued, except as provided in Section 9. If the Optionee is an Employee, the Optionee understands and acknowledges that, except as otherwise provided in a separate, written employment agreement between a Participating Company and the Optionee, the Optionee’s employment is “at will” and is for no specified term. Nothing in this Option Agreement shall confer upon the Optionee, whether an Employee, Director or Consultant, any right to continue in the Service of a Participating Company or interfere in any way with any right of the Participating Company Group to terminate the Optionee’s Service as an Employee, Director or Consultant, as the case may be, at any time.

11. NOTICE OF SALES UPON DISQUALIFYING DISPOSITION.

The Optionee shall dispose of the shares acquired pursuant to the Option only in accordance with the provisions of this Option Agreement. In addition, the Optionee shall promptly notify the Chief Financial Officer or Controller of the Company if the Optionee disposes of any of the shares acquired pursuant to the Option within one (1) year after the date of the Optionee exercises all or part of the Option or within two (2) years after the Date of Option Grant. Until such time as the Optionee disposes of such shares in a manner consistent with the provisions of this Option Agreement, unless otherwise expressly authorized by the Company, the Optionee shall hold all shares acquired pursuant to the Option in the Optionee’s name (and not in the name of any nominee) for the one-year period immediately after the exercise of the Option and the two-year period immediately after Date of Option Grant. At any time during the one-year or two-year periods set forth above, the Company may place a legend on any certificate representing shares acquired pursuant to the Option requesting the transfer agent for the Company’s stock to notify the Company of any such transfers. The obligation of the Optionee to notify the Company of any such transfer shall continue notwithstanding that a legend has been placed on the certificate pursuant to the preceding sentence.

12. LEGENDS.

The Company may at any time place legends referencing any applicable federal, state or foreign securities law restrictions on all certificates representing shares of Stock subject to the provisions of this Option Agreement. The Optionee shall, at the request of the Company, promptly present to the Company any and all certificates representing shares of Stock acquired pursuant to the Option in the possession of the Optionee in order to carry out the provisions of this Section 12.

13. ARBITRATION.

In the event a dispute between the parties to this Option Agreement arises out of, in connection with, or with respect to this Option Agreement, or any breach of this Option Agreement, such dispute will, on the written request of one (1) party delivered to the other party, be submitted and settled by arbitration in Fremont, California in accordance with the rules of the American Arbitration Association then in effect and will comply with the California Arbitration

12

Act, except as otherwise specifically stated in this Section 13. Judgment upon the award rendered by the arbitrators may be entered in any court having jurisdiction. The parties submit to the in personam jurisdiction of the Supreme Court of the State of California for the purpose of confirming any such award and entering judgment upon the award. Notwithstanding anything to the contrary that may now or in the future be contained in the rules of the American Arbitration Association, the parties agree as follows:

13.1 Each party will appoint one individual approved by the American Arbitration Association to hear and determine the dispute within twenty (20) days after receipt of notice of arbitration from the noticing party. The two (2) individuals so chosen will select a third impartial arbitrator. The majority decision of the arbitrators will be final and binding upon the parties to the arbitration. If either party fails to designate its arbitrator within twenty (20) days after delivery of the notice provided for in this Section 13.1, then the arbitrator designated by the one (1) party will act as the sole arbitrator and will be considered the single, mutually approved arbitrator to resolve the controversy. In the event the parties are unable to agree upon a rate of compensation for the arbitrators, they will be compensated for their services at a rate to be determined by the American Arbitration Association.

13.2 The parties will enjoy, but are not limited to, the same rights to discovery as they would have in the United States District Court for the Northern District of California.

13.3 The arbitrators will, upon the request of either party, issue a written opinion of their findings of fact and conclusions of law.

13.4 Upon receipt by the requesting party of said written opinion, said party will have the right within ten (10) days to file with the arbitrators a motion to reconsider, and upon receipt of a timely request the arbitrators will reconsider the issues raised by said motion and either confirm or change their majority decision which will then be final and binding upon the parties to the arbitration.

13.5 The arbitrators will award to the prevailing party in any such arbitration reasonable expenses, including attorneys’ fees and costs, incurred in connection with the dispute.

14. MISCELLANEOUS PROVISIONS.

14.1 Binding Effect. Subject to the restrictions on transfer set forth herein, this Option Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective heirs, executors, administrators, successors and assigns.

14.2 Termination or Amendment. The Board may terminate or amend the Plan or the Option at any time; provided, however, that except as provided in Section 8.2 in connection with a Change in Control, no such termination or amendment may adversely affect the Option or any unexercised portion hereof without the consent of the Optionee unless such termination or amendment is necessary to comply with any applicable law or government regulation or is required to enable the Option to qualify as an incentive stock option. No amendment or addition to this Option Agreement shall be effective unless in writing.

13

14.3 Notices. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given (except to the extent that this Option Agreement provides for effectiveness only upon actual receipt of such notice) upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail, with postage and fees prepaid, addressed to the other party at the address of such party as set forth in the Notice or at such other address as such party may designate in writing from time to time to the other party.

14.4 Integrated Agreement. This Option Agreement and the Notice constitute the entire understanding and agreement of the Optionee and the Participating Company Group with respect to the subject matter contained herein and therein, and there are no agreements, understandings, restrictions, representations, or warranties among the Optionee and the Participating Company Group with respect to such subject matter other than those as set forth or provided for herein or therein. To the extent contemplated herein, the provisions of this Option Agreement shall survive any exercise of the Option and shall remain in full force and effect.

14.5 Applicable Law. This Option Agreement shall be governed by the laws of the State of California as such laws are applied to agreements between California residents entered into and to be performed entirely within the State of California.

14

PDL BIOPHARMA, INC.

STOCK OPTION (INCENTIVE)

EXERCISE NOTICE

PDL BioPharma, Inc.

Attention: Stock Administrator

34801 Campus Drive

Fremont, CA 94555

Ladies and Gentlemen:

1. Option. I was granted an incentive stock option (“Option”) to purchase shares of the common stock (“Shares”) of PDL BioPharma, Inc. (“Company”) pursuant to the Company’s 1999 Stock Option Plan (the “Plan”) as follows:

2. Exercise of Option. I hereby elect to exercise the Option to purchase the following number of shares, all of which have vested in accordance with my Option Agreement:

3. Payment. I enclose payment in full of the total exercise price for the Shares in the following form(s), as authorized by my Option Agreement:

1

4. Tax Withholding. I authorize payroll withholding and otherwise will make adequate provision for federal, state, local and foreign tax withholding obligations of the Company, if any, in connection with my exercise of the Option and my subsequent disposition of the Shares.

5. Notice of Disqualifying Disposition. I agree that I will promptly notify the Chief Financial Officer or Controller of the Company if I transfer any of the Shares within one (1) year from the date I exercise all or part of the Option or within two (2) years of the Date of Option Grant.

6. Optionee Information.

I understand that I am purchasing the Shares pursuant to the terms of the Plan and my Option Agreement, a copy of which I have received and have carefully read and understand.

Receipt of the above is hereby acknowledged:

2