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                               VICAL INCORPORATED
                             9373 TOWNE CENTRE DRIVE               EXHIBIT 10.28
                                    SUITE 100
                               SAN DIEGO, CA 92121

                                February 5, 2002

Mr. Vijay B. Samant

RE:    AMENDMENT TO NOVEMBER 28, 2000 LETTER REGARDING EMPLOYMENT TERMS

Dear Vijay:

This Amendment (the "AMENDMENT") to your Letter Agreement with Vical
Incorporated (the "COMPANY") dated November 28, 2000 (the "AGREEMENT") will
amend the terms and conditions of the Agreement to the extent provided herein.
Except as specifically amended by this Amendment, the terms and conditions of
the Agreement shall remain in full force and effect.

Paragraph 6 of the Agreement is hereby deleted in its entirety and replaced with
the following:

       "6.   RELOCATION. To assist you in moving to the San Diego area, we are
             prepared to pay the reasonable and customary expenses of relocating
             you and your family, not to exceed $60,000 (the aggregate amount of
             relocation expenses for which you are entitled to reimbursement
             hereunder shall be referred to herein as the "Relocation Expense
             Amount"), and such Relocation Expense Amount shall be subject to
             offset as provided in this Section 6 below. In addition, in the
             event your residence in Pennsylvania is prepared and maintained
             (including customary insurance coverage) for sale in reasonable
             condition and listed for sale by September 1, 2002, the Company
             will reimburse you up to $100,000 of any loss you incur on its
             sale; PROVIDED THAT, in the event such a loss is anticipated,
             the Company or its designees may, at the Company's sole discretion,
             purchase that residence for an amount equal to its cost to you
             (estimated to be approximately $550,000). The Company will also
             loan to you an amount not to exceed $500,000 for the purpose of
             purchasing a residence in the San Diego area, such loan to be
             evidenced by a promissory note bearing interest at the lowest
             applicable federal rate necessary to avoid imputed interest income
             under the Internal Revenue Code and secured by a second deed of
             trust on the residence. The loan will be due and payable upon the
             earlier of (A) the sale of that residence, (B) 90 days following
             the termination of your employment for any reason or (C) January 1,
             2007. Once you and your family have relocated to the San Diego
             area, the Company will provide to you for a period not to exceed 24
             months, a monthly housing cost-of-living differential payment of up
             to $2,500 per month. Further, the Company will either pay the
             costs, not to exceed $3,500 per month, of temporary housing for you
             in San Diego or, at the Company's option, provide temporary housing
             to you until the earlier of your purchase of a San Diego residence
             or

                                       1.
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             December 31, 2002. You shall also receive the following: (i) a
             payment from the Company sufficient to pay the income, employment
             and any other taxes you incur arising from the actual monthly
             temporary housing payments received by you or, if the Company
             provides temporary housing to you, the amount of income imputed to
             you with respect thereto; and (ii) an additional payment from the
             Company sufficient to pay the income, employment and any other
             taxes arising from the payments made by the Company pursuant to
             Section 6(i) above and this Section 6(ii) so that you shall be
             fully reimbursed for any income, employment and any other taxes you
             incur associated with the payments to reimburse you for such
             income, employment and other taxes on such amounts (the aggregate
             amount paid to you under Sections 6(i) and 6(ii) herein shall be
             referred to herein as the "Gross-up Amount"). The Gross-up Amount
             shall be offset against and, thus, subtracted from the Relocation
             Expense Amount but, in no event, shall the Relocation Expense
             Amount be less than zero. The Company will also reimburse you for
             the reasonable costs of one trip per month in connection with your
             commuting to San Diego from your home in Pennsylvania, until the
             earlier of your purchase of a San Diego residence or December 31,
             2002. Except as specifically provided herein, you will be
             responsible for any personal taxes (income, employment or
             otherwise) arising from any of the payments described herein,
             except that the Company will reimburse you for personal taxes
             arising from the payment of any Relocation Expense Amount (to the
             extent not offset by the Gross-up Amount).

This Amendment shall be governed by and construed in accordance with the laws of
the State of California, without regard to conflicts of law principles.

Please sign and date this Amendment and return it to me at your earliest
convenience.

Sincerely,

VICAL INCORPORATED

By: /s/  MARTHA J. DEMSKI
   ----------------------
         Martha J. Demski
         Vice President & Chief Financial Officer

ACCEPTED AND AGREED:

/s/  VIJAY B. SAMANT
--------------------
     Vijay B. Samant

MARCH 8, 2002

Date

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Exhibit 10.33  

 
 

EXECUTIVE EMPLOYMENT AGREEMENT    
  

        THIS EXECUTIVE EMPLOYMENT AGREEMENT ("Agreement") is made and entered into as of the 26th day of October, 2001, by
and between SEATTLE GENETICS, INC., a Delaware corporation ("Company") and CLAY B. SIEGALL ("Executive"). 

 
 

RECITALS:    
  

        A.    The Company desires that Executive continue his services as the President and Chief Scientific Officer of the Company,
having been duly appointed to such position by the Board of Directors of the Company. 

        B.    Executive desires to continue in such engagement. 

        C.    This Agreement contains other provisions applicable to the employment of Executive by the Company. 

        In
consideration of the above Recitals and the provisions of this Agreement, the Company and Executive agree as follows: 

I. DUTIES  

        1.1    Title and Responsibilities.    Executive shall serve as President and Chief Scientific Officer of the Company.
Executive's responsibilities and duties shall include those inherent in Executive's position with the Company and shall further include such other managerial responsibilities and executive duties
consistent with such position as may be assigned to him from time to time by the Chairman of the Board or the Board of Directors of the Company. Executive shall devote his best efforts and full
business time to the business and interests of the Company. During the term of his employment with the Company, Executive may serve on the board of directors of other companies, manage personal
investments, and engage in civic and charitable activities, provided that such activities shall not represent a conflict of interest with the Company and do not materially detract from fulfilling
Executive's responsibilities and duties to the Company. 

        1.2    Board of Directors.    The Board of Directors of the Company shall take whatever steps are necessary to
continue to nominate Executive for election to the Board of Directors of the Company in every election of Executive's class of directors presented to stockholders following execution of this
Agreement. 

II. COMPENSATION  

        2.1    Base Salary.    Executive shall be paid a base salary ("Base
Salary") by the Company during the term of Executive's employment with the Company at the rate of Two Hundred Ten Thousand and 00/100 Dollars ($210,000.00) per year.
Executive's Base Salary shall be reviewed annually by the Board of Directors and evaluated based on performance and salary levels of other executives of comparable position within the industry and
geographic location of the Company. Based upon such evaluation and review, Executive's Base Salary may be increased from time to time as determined by the Board of Directors of the Company in its sole
discretion. 

        2.2    Bonus.    In addition to Base Salary, Executive may receive an annual bonus ("Bonus") based upon performance
criteria and financial and operational results of the Company as determined by the Board of Directors of the Company. 

        2.3    Stock Options.    Executive may be eligible to receive additional grants of stock options or purchase rights
from time to time in the future, on such terms and subject to such conditions as the Board of Directors shall determine as of the date of any such grant and pursuant to the existing stock plans of the
Company. 

 

        2.4    Other Benefits.    

          (i)  Executive
shall be entitled to such employee benefits generally available to the full-time salaried employees of the Company, including without limitation,
health insurance, paid vacation of not less than four (4) weeks per year, retirement plans and other similar benefits. 

        (ii)  The
Company shall pay or reimburse Executive for all travel and entertainment expenses incurred by Executive in connection with his duties on behalf of the Company,
subject to the reasonable approval of the Company. Executive shall only be entitled to reimbursement to the extent that Executive follows the reasonable procedures established by the Company for
reimbursement of such expenses which will include, but will not be limited to, providing satisfactory evidence of such expenditures. 

III. TERMINATION OF EMPLOYMENT  

        3.1    Termination of Employment and Severance Benefits.    

        (a)    Termination of Employment.    This Agreement may be terminated upon the occurrence of any of the following
events: 

          (i)  The
Company's determination in good faith that it is terminating Executive for Cause (as defined in Section 3.3 below) ("Termination for
Cause"); 

        (ii)  The
Company's determination that it is terminating Executive without Cause, which determination may be made by the Company at any time at the Company's sole discretion,
for any or no reason ("Termination Without Cause"); 

        (iii)  The
effective date of a written notice sent to the Company from Executive stating that Executive is electing to terminate his employment with the Company
("Voluntary Termination"); 

        (iv)  A
change in Executive's status such that a Constructive Termination (as defined in Section 3.2(d) below) has
occurred; or 

        (v)  Following
Executive's death or Disability (as defined in Section 3.4 below). 

        3.2    Severance Benefits.    Executive shall be entitled to receive severance benefits upon termination of employment
only as set forth in this Section 3.2: 

        (a)    Voluntary Termination.    If Executive's employment terminates by Voluntary Termination, then Executive shall
not be entitled to receive payment of any severance benefits. Executive will receive payment(s) for all salary and unpaid vacation accrued as of the date of Executive's termination of employment and
Executive's benefits will be continued under the Company's then existing benefit plans and policies in accordance with such plans and policies in effect on the date of termination and in accordance
with applicable law. 

        (b)    Involuntary Termination.    If Executive's employment is terminated under Section 3.1(a)(ii)
(Termination Without Cause) or 3.1(a)(iv) (Constructive Termination) above (such termination, an "Involuntary Termination"), Executive will be entitled
to receive payment of severance benefits equal to Executive's regular monthly salary for twelve (12) months (the "Severance Period"). Such
payments shall be made, at the Company's option, in a lump sum within thirty (30) days after the effective date of termination, or ratably over the Severance Period according to the Company's
standard payroll schedule. Executive will also be entitled to receive payment on the date of termination of any bonus which has been earned under Section 2.2, but not yet paid, and the pro rata
portion of any bonus based on achievement of the specific corporate and individual performance targets established for the fiscal year in which the termination occurs. 

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Health insurance benefits with the same coverage provided to Executive prior to the termination (e.g. medical, dental, optical, mental health) and in all other respects significantly comparable to
those in place immediately prior to the termination will be provided at the Company's cost over the Severance Period. In addition, the vesting of any unvested stock options or shares of restricted
stock held by Executive as of the date of Executive's termination of employment shall accelerate such that the options or restricted securities shall become vested as to an additional twelve
(12) months of vesting. 

        (c)    Termination for Cause.    If Executive's employment is terminated for Cause, then Executive shall not be
entitled to receive payment of any severance benefits. Executive will receive payment(s) for all salary and unpaid vacation accrued as of the date of Executive's termination of employment and
Executive's benefits will be continued under the Company's then existing benefit plans and policies in accordance with such plans and policies in effect on the date of termination and in accordance
with applicable law. 

        (d)    Constructive Termination. "Constructive Termination" shall be deemed to occur if (A)(1) there is a material
reduction or change in job duties, responsibilities and requirements inconsistent with Executive's position with the Company and prior duties, responsibilities and requirements, provided that neither
a mere change in title alone nor reassignment to a position that is substantially similar to the position held prior to the change in terms of job duties, responsibilities or requirements shall
constitute a material reduction in job responsibilities; or (2) there is a reduction in Executive's then-current base salary by at least 20%, provided that an
across-the-board reduction in the salary level of all other senior executives by the same percentage amount as part of a general salary level reduction shall not constitute
such a salary reduction; or (3) Executive refuses to relocate to a facility or location more than 50 miles from the Company's current location; and (B) within the 30-day
period immediately following such event Executive elects to terminate his employment voluntarily. 

        (e)    Termination by Reason of Death or Disability.    In the event that Executive's employment with the Company
terminates as a result of Executive's death or Disability (as defined in Section 3.4 below), Executive or Executive's estate or representative
will receive all salary and unpaid vacation accrued as of the date of Executive's death or Disability and any other benefits payable under the Company's then existing benefit plans and policies in
accordance with such plans and policies in effect on the date of death or Disability and in accordance with applicable law. In addition, Executive's estate or representative will receive the amount of
Executive's target bonus for the fiscal year in which the death or Disability occurs to the extent that the bonus has been earned as of the date of Executive's death or Disability, as determined by
the Board of Directors or its Compensation Committee based on the specific corporate and individual performance targets established for such fiscal year. 

        3.3    Definition of Cause.    For purposes of this Agreement, "Cause"
for Executive's termination will exist at any time after the happening of one or more of the following events: 

        (a)  An
action or omission of the Executive which constitutes a willful and intentional material breach of this Agreement or the Confidentiality Agreement (defined below),
including without limitation, Executive's theft or other misappropriation of the Company's proprietary information; 

        (b)  Executive's
commitment of fraud, embezzlement, misappropriation of funds or breach of trust in connection with his employment; or 

        (c)  Executive's
conviction of any crime which involves dishonesty or a breach of trust, or gross negligence in connection with the performance of the Executive's duties. 

3

 

        3.4.    Definition of Disability.    For purposes of this Agreement and subject to the requirements of the Americans
With Disabilities Act and analogous state law, "Disability" shall mean that Executive has been unable to perform his duties hereunder as the result of
his incapacity due to physical or mental illness, and such inability, which continues for at least 120 consecutive calendar days or 150 calendar days during any consecutive twelve-month period, if
shorter, after its commencement, is determined to be total and permanent by a physician selected by the Company and its insurers and acceptable to Executive or to Executive's legal representative
(with such agreement on acceptability not to be unreasonably withheld). 

IV. CHANGE OF CONTROL  

        4.1    Accelerated Vesting.    In the event of a Change of Control (as defined below), the vesting of all of
Executive's stock options or shares of restricted stock then held by Executive at the time of such Change in Control shall be accelerated completely so that one hundred percent (100%) of the shares of
Common Stock covered by the stock options or shares of restricted stock are fully vested and exercisable. 

        For
purposes of this Agreement, "Change of Control" shall mean the occurrence of any of the following events: (i) an acquisition of
the Company by another entity by means of any transaction or series of related transactions (including, without limitation, any reorganization, merger or consolidation but excluding any merger
effected exclusively for the purpose of changing the domicile of the Company), or (ii) a sale of all or substantially all of the assets of the Company (collectively, a
"Merger"), so long as in either case the Company's stockholders of record immediately prior to such Merger will, immediately after such Merger, hold
less than 50% of the voting power of the surviving or acquiring entity. 

V. RESTRICTIVE COVENANTS  

        5.1    Confidentiality Agreement.    Executive shall sign, or has signed the Company's form of Proprietary Information
and Inventions Agreement (the "Confidentiality Agreement") substantially in the form
attached hereto as Exhibit A. Executive hereby represents and warrants to the Company that he has complied with all obligations under the
Confidentiality Agreement and agrees to continue to abide by the terms of the Confidentiality Agreement and further agrees that the provisions of the Confidentiality Agreement shall survive any
termination of this Agreement or of Executive's employment relationship with the Company, including the noncompetition provisions of the Confidentiality Agreement in Sections 11 and 12 thereof. 

VI. OTHER PROVISIONS  

        6.1    Limitation on Stock Option Acceleration Benefits.    In the event that any stock option acceleration benefits
provided for in this Agreement to Executive (i) constitute "parachute payments" within the meaning of Section 280G of the Internal Revenue Code of 1986, as amended (the
"Code") and (ii) but for this Section 6.1, would be subject to the excise tax imposed by Section 4999 of the Code, then Executive's
acceleration benefits under Section 3.2(b) shall be payable either: 

        (a)  in
full, or 

        (b)  as
to such lesser amount which would result in no portion of such benefits being subject to excise tax under Section 4999 of the Code, 

whichever
of the foregoing amounts, taking into account the applicable federal, state and local income taxes and the excise tax imposed by Section 4999, results in the receipt by Executive on
an after-tax basis, of the greatest amount of benefits under Section 3.2(b) notwithstanding that all or some portion of such benefits may be taxable under Section 4999 of the
Code. Unless the Company or Executive 

4

 

otherwise agree in writing, any determination required under this Section 6.1 shall be made in writing by independent public accountants appointed by Employee and reasonably acceptable to the
Company (the "Accountants"), whose determination shall be conclusive and binding upon Executive and the Company for all purposes. For purposes of making
the calculations required by this Section 6.1, the Accountants may make reasonable assumptions and approximations concerning applicable taxes and may rely on reasonable, good faith
interpretations concerning the application of Sections 280G and 4999 of the Code. The Company and Executive shall furnish to the Accountants such information and documents as the Accountants
may reasonably request in order to make a determination under this Section 6.1. The Company shall bear all costs the Accountants may reasonably incur in connection with any calculations
contemplated by this Section 6.1. 

        6.2    Indemnification.    The Company hereby agrees to indemnify and hold the Executive harmless, to the fullest
extent permitted by law and as set forth in the Amended and Restated Certificate of Incorporation of the Company, from and against any expenses, including legal fees, and all judgments, fines and
amounts paid in settlement and reasonably incurred in connection with legal, administrative or investigative proceedings to which the Executive is made, or threatened to be made, a party by reason of
the fact the Executive is or was a director or officer of the Company. 

        6.3    Entire Agreement.    This Agreement contains the entire agreement and understanding of the parties with respect
to Executive's employment by the Company and compensation payable to Executive by the Company and supersedes all prior understandings, agreements and discussions. This Agreement may only be amended or
modified by a written instrument executed by Executive and the Chairman of the Board of the Company pursuant to authorization by the Board of Directors. 

        6.4    Notices.    Any and all notices permitted or required to be given under this Agreement must be in writing.
Notices will be deemed given (i) on the first business day after having been sent by commercial overnight courier with written verification of receipt, or (ii) on the third business day after having
been sent by registered or certified mail from a location on the United States mainland, return receipt requested, postage prepaid, whichever occurs first, at the address set forth below or at any new
address, notice of which will have been given in accordance with this Section 6.4: 

	If to the Company	 	Seattle Genetics, Inc.

c/o OVP Venture Partners

2420 Carillon Point

Kirkland, WA 98033

Attn: Charles Waite, Chairman, Board of Directors
	

with a copy to:	
 	

Venture Law Group

4750 Carillon Point

Kirkland, WA 98033

Attn: Sonya Erickson
	

If to Executive:	
 	

Clay B. Siegall

c/o Seattle Genetics, Inc.

21823 30th Dr. SE

Bothell, WA 98021

        6.5    Non-Waiver.    Failure to enforce at any time any of the provisions of this Agreement shall not be
interpreted to be a waiver of such provisions or to affect either the validity of this Agreement or the right of either party thereafter to enforce each and every provision of this Agreement. 

        6.6    Separability.    If one or more provisions of this Agreement is finally determined to be invalid or
unenforceable, such provision will not affect or impair the other provisions of this Agreement, all of which will continue to be in effect and will be enforceable, provided, however, that any such
invalid 

5

 

provisions shall, to the extent possible, be reformed so as to implement insofar as practicable the intentions of the parties. 

        6.7    Term.    The employment of Executive under this Agreement shall be for an unspecified term. The Company and
Executive acknowledge and agree that Executive's employment is and shall continue to be at-will, as defined under applicable law, and that Executive's employment with the Company may be
terminated by either party at any time for any or no reason, and with or without notice. If Executive's employment terminates for any reason, Executive shall not be entitled to any payments, benefits,
damages award or compensation other than as provided in this Agreement. 

        6.8    Law.    This Agreement shall be interpreted in accordance with the laws of the State of Washington. 

        6.9    No Duty to Mitigate.    Executive shall not be required to mitigate the amount of any payment contemplated by
this Agreement (whether by seeking new employment or in any other manner), nor, except as otherwise provided in this Agreement, shall any such payment be reduced by any earnings that Executive may
receive from any other source. 

        6.10    Legal Fees.    In the event either party breaches this Agreement, the nonbreaching party shall be en entitled
to recover from the breaching party any and all damages, costs and expenses, including without limitation, attorneys' fees and court costs, incurred by the nonbreaching party as a result of the
breach. 

        6.11    Counterparts.    This Agreement may be executed in counterparts which when taken together will constitute one
instrument. Any copy of this Agreement with the original signatures of all parties appended will constitute an original. 

6

 

        IN
WITNESS WHEREOF, the parties have executed this Agreement as of the day and year first above written. 

	 	 	SEATTLE GENETICS, INC.
	

 	
 	

By:	

/s/  CHARLES P. WAITE      

	 	 	Title:	Chairman of the Board
	

 	
 	
EXECUTIVE
	

 	
 	

/s/  CLAY B. SIEGALL      
CLAY B. SIEGALL

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