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                                                                   EXHIBIT 10.10

                              EMPLOYMENT AGREEMENT

This Agreement is made by and between diaDexus (the Company), and Mohan Iyer
(Executive) as of December 1, 1999.

       1. Duties and Scope of Employment.

              (a) Positions; Promotion Commencement Date; Duties. Executive's
promotion with the Company pursuant to this Agreement shall commence on December
1, 1999 (the Promotion Commencement Date). As of the Promotion Commencement
Date, the Company shall employ the Executive as the Vice President of R&D
Operations and Business Development of the Company, reporting to the Chief
Operating Officer for Business Development responsibilities and to the Chief
Science Officer for R&D Operations. The period of Executive's employment
hereunder is referred to herein as the Employment Term. During the Employment
Term, Executive shall render such business and professional services in the
performance of his duties, consistent with Executive's position within the
Company, as shall reasonably be assigned to him by the Chief Operating Officer,
the Chief Science Officer and the Board of Directors (the "Board").

              (b) Obligations. During the Employment Term, Executive shall
devote his full business efforts and time to the Company. Executive agrees,
during the Employment Term, not to actively engage in any other employment,
occupation or consulting activity for any direct or indirect remuneration
without the prior approval of the Board; provided, however, that Executive may
serve in any capacity with any civic, educational or charitable organization, or
as a member of corporate Boards of Directors or committees thereof upon which
Executive currently serves, without the approval of the Board; provided, further
that Executive may devote a reasonable amount of time to managing his family
investments.

       2. Employee Benefits: Indemnification Agreement. During the Employment
Term, Executive shall be eligible to participate in the employee benefit plans
maintained by the Company that are applicable to other senior management to the
full extent provided for under those plans. Upon his Promotion Commencement
Date, Executive shall be offered an indemnification agreement comparable in form
and substance to indemnification agreements previously entered into by and
between the Company and its executive officers.

       3. At-Will Employment. Executive and the Company understand and
acknowledge that Executive's employment with the Company constitutes at-will
employment. Subject to the Company's obligation to provide severance benefits as
specified herein, Executive and the Company acknowledge that this employment
relationship may be terminated at any time, upon written notice to the other
party,



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with or without good cause or for any or no cause, at the option either of the
Company or Executive.

       4. Compensation.

              (a) Base Salary. While employed by the Company, the Company shall
pay the Executive as compensation for his services a base salary at the
annualized rate of $155,000 (the Base Salary). Such salary shall be paid
periodically in accordance with normal Company payroll practices and subject to
the usual, required withholding. Executive's Base Salary shall be reviewed
annually by the Chief Operating Officer and the Compensation Committee of the
Board for possible increases in light of Executive's performance and competitive
data.

              (b) Bonuses. Executive shall be eligible to earn a target bonus of
up to 25% of Base Salary (the Target Bonus). Executive's performance shall be
evaluated by the Chief Operating Officer and the Chief Science Officer based
upon agreed performance criteria. The payment of any bonus under this Section
4(b) shall be subject to Executive's employment with the Company through the end
of the relevant evaluation period. Executive's Target Bonus shall be reviewed
annually by the Chief Executive Officer and Compensation Committee of the Board
for possible increases in light of Executive's performance and competitive data.

              (c) Equity Compensation.

                     (i) Stock Options. As of the Promotion Commencement Date,
Executive shall be granted additional stock options (the Stock Options) to
purchase 70,000 shares of Company common stock subject to Board approval in
accordance with the Company's employee stock option plan.

              (d) Severance.

                     (i) Voluntary Termination for Good Reason; Involuntary
Termination Other Than for Cause. If Executive's employment with the Company is
voluntarily terminated by Executive for Good Reason (as defined below) or is
involuntarily terminated by the Company other than for Cause (as defined below),
then, subject to Executive executing and not revoking a standard form of mutual
release of claims with the Company (i) Executive shall receive continued
payments of one year's Base Salary, less applicable withholding, in accordance
with the Company's standard payroll practices, and (ii) the Company shall pay
the group health, dental and vision plan continuation coverage premiums for
Executive and, if relevant, his covered dependents under Title X of the
Consolidated Budget Reconciliation Act of 1985, as amended ("COBRA") for the
lesser of (A) twelve (12) months from the date of



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Executive's termination of employment, or (B) the date upon which Executive and
his covered dependents are covered by similar plans of Executive's new
employer.

       For the purposes of this Agreement, Cause means (i) a material act of
dishonesty made by Executive in connection with Executive's responsibilities as
an employee, (ii) Executive's conviction of, or plea of nolo contendere to, a
felony, (iii) Executive's gross misconduct in connection with the performance of
his duties hereunder, (iv) Executive's death or permanent disability or (v)
Executive's material breach of his obligations under this Agreement; provided,
however, that with respect to clauses (iii) and (v), such actions shall not
constitute Cause if they are cured by Executive within thirty (30) days
following delivery to Executive of a written explanation specifying the basis
for the Company's beliefs with respect to such clauses.

       For the purposes of this Agreement, Good Reason means (i) a reduction in
Executive's Base Salary, (ii) a reduction in Executive's title (whether or not
material) or a material reduction in Executive's authority or duties including
due to a Change in Control (as defined below), (iii) the requirement that
Executive relocate from him current place of residence or that the company
headquarters relocate more than 15 miles from Santa Clara, or (iv) the Company's
material breach of its obligations under this Agreement; provided, however, that
with respect to clause (iv), such material breach shall not constitute Cause if
it is cured by the Company within thirty (30) days following delivery to the
Company of a written explanation specifying the basis for the Executive's
beliefs with respect to such clause.

       The Executive shall not be required to mitigate the value of any
severance benefits contemplated by Section 4 of this Agreement, nor shall any
such benefits be reduced by any earnings or benefits that the Executive may
receive from any other source.

       For the purposes of this Agreement, Change of Control is defined as:

                     (a) Any person (as such term is used in Sections 13(d) and
14(d) of the Securities Exchange Act of 1934, as amended) becomes the beneficial
owner (as defined in Rule 13d-3 under said Act), directly or indirectly, of
securities of the Company representing fifty percent (50%) or more of the total
voting power represented by the Company's then outstanding voting securities; or

                     (b) A change in the composition of the Board occurring
within a two-year period, as a result of which fewer than a majority of the
directors are Incumbent Directors. Incumbent Directors shall mean directors who
either (A) are directors of the Company as of the date hereof, or (B) are
elected, or nominated for election, to the Board with the affirmative votes of
at least a majority of the Incumbent Directors at the time of such election or
nomination (but shall not include an individual



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whose election or nomination is in connection with an actual or threatened proxy
contest relating to the election of directors to the Company); or

                     (c) The consummation of a merger or consolidation of the
Company with any other corporation, other than a merger or consolidation which
would result in the voting securities of the Company outstanding immediately
prior thereto continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity) at least fifty
percent (50%) of the total voting power represented by the voting securities of
the Company or such surviving entity outstanding immediately after such merger
or consolidation; or

                     (d) The consummation of the sale or disposition by the
Company of all or substantially all of the Company's assets.

       5. Total Disability of Executive. Upon Executive's becoming permanently
and totally disabled (as defined in accordance with Internal Revenue Code
Section 22(e)(3) or its successor provision) during the term of this Agreement,
employment hereunder shall automatically terminate, all payments of compensation
by the Company to Executive hereunder shall immediately terminate (except as to
amounts already earned) and all vesting of the Executive's Stock Options and
Restricted Stock shall immediately cease.

       6. Death of Executive. If Executive dies while employed by the Company
pursuant to this Agreement, all payments of compensation by the Company to
Executive hereunder shall immediately terminate (except as to amounts already
earned, which shall be paid to his estate) and all vesting of the Executive's
Stock Options and Restricted Stock shall immediately cease.

       7. Assignment. This Agreement shall be binding upon and inure to the
benefit of (a) the heirs, beneficiaries, executors and legal representatives of
Executive upon Executive's death and (b) any successor of the Company. Any such
successor of the Company shall be deemed substituted for the Company under the
terms of this Agreement for all purposes. As used herein, successor shall
include any person, firm, corporation or other business entity which at any
time, whether by purchase, merger or otherwise, directly or indirectly acquires
all or substantially all of the assets or business of the Company. None of the
rights of Executive to receive any form of compensation payable pursuant to this
Agreement shall be assignable or transferable except through a testamentary
disposition or by the laws of descent and distribution upon the death of
Executive. Any attempted assignment, transfer, conveyance or other disposition
(other than as aforesaid) of any interest in the rights of Executive to receive
any form of compensation hereunder shall be null and void; provided, however,
that Executive shall be allowed to transfer vested Stock Options and Restricted
Stock



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consistently with the rules under Form S-8 for estate planning and wealth
management purposes.

       8. Notices. A11 notices, requests, demands and other communications
called for hereunder shall be in writing and shall be deemed given if (i)
delivered personally or by facsimile, (ii) one (1) day after being sent by
Federal Express or a similar commercial overnight service, or (iii) three (3)
days after being mailed by registered or certified mail, return receipt
requested, prepaid and addressed to the parties or their successors in interest
at the following addresses, or at such other addresses as the parties may
designate by written notice in the manner aforesaid:

                              If to the Company: .
                              Attn: Chief Operating Officer
                              diaDexus, LLC
                              3303 Octavius Drive
                              Santa Clara, CA 95054

       If to Executive:

                              Mohan Iyer
                              308 Hedge Road
                              Menlo Park, California 94025

                              Or at the last residential address known by the
Company.

       9. Severability. In the event that any provision hereof becomes or is
declared by a court of competent jurisdiction to be illegal, unenforceable or
void, this Agreement shall continue in full force and effect without said
provision.

       10. Proprietary Information Agreement. Executive acknowledges the
Company's standard Employee Proprietary Information Agreement (the Proprietary
Information Agreement) entered into on his initial hire into the Company is
still operative.

       11. Entire Agreement. This Agreement, the Stock Plan, the Option
Agreements, the Restricted Stock Purchase Agreement, the indemnification
agreement and employee benefit plans referred to in Section 2 and the
Proprietary Information Agreement represent the entire agreement and
understanding between the Company and Executive concerning Executive's
employment relationship with the Company, and



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supersede and replace any and all prior agreements and understandings concerning
Executive's employment relationship with the Company.

       12. Non-Binding Mediation, Arbitration and Equitable Relief.

              (a) The parties agree to make a good faith attempt to resolve any
dispute or claim arising out of or related to this Agreement through
negotiation. In the event that any dispute or claim arising out of or related to
this Agreement is not settled by the parties hereto, the parties will attempt in
good faith to resolve such dispute or claim by non-binding mediation in Santa
Clara County, California to be conducted by one mediator belonging to the
American Arbitration Association. The mediation shall be held within thirty (30)
days of the request therefor. The costs of the mediation shall be borne equally
by the parties to the mediation.

              (b) Except as provided in Section 13(e) below, Executive and the
Company agree that, to the extent permitted by law, any dispute or controversy
arising out of, relating to, or in connection with this Agreement, or the
interpretation, validity, construction, performance, breach, or termination
thereof which has not been resolved by negotiation or mediation as set forth in
Section 13(a) shall be finally settled by binding arbitration to be held in
Santa Clara County, California, in accordance with the National Rules for the
Resolution of Employment Disputes then in effect of the American Arbitration
Association (the Rules). The arbitrator may grant injunctions or other relief in
such dispute or controversy. The decision of the arbitrator shall be
confidential, final, conclusive and binding on the parties to the arbitration.
Judgment may be entered under a protective order on the arbitrator's decision in
any court having jurisdiction.

              (c) The arbitrator shall apply California law to the merits of any
dispute or claim, without reference to rules of conflict of law. The arbitration
proceedings shall be governed by federal arbitration law and by the Rules,
without reference to state arbitration law. Executive hereby expressly consents
to the personal jurisdiction of the state and federal courts located in
California for any action or proceeding arising from or relating to this
Agreement and/or relating to any arbitration in which the parties are
participants.

              (d) Executive understands that nothing in Section 13 modifies
Executive's at-will status. Either the Company or Executive can terminate the
employment relationship at any time, with or without cause.

              (e) EXECUTIVE HAS READ AND UNDERSTANDS SECTION 13, WHICH DISCUSSES
ARBITRATION. EXECUTIVE UNDERSTANDS THAT BY SIGNING THIS AGREEMENT, EXECUTIVE
AGREES, TO THE EXTENT PERMITTED BY LAW, TO SUBMIT ANY FUTURE CLAIMS ARISING OUT
OF,



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RELATING TO, OR IN CONNECTION WITH THIS AGREEMENT, OR THE INTERPRETATION,
VALIDITY, CONSTRUCTION, PERFORMANCE, BREACH, OR TERMINATION THEREOF TO BINDING
ARBITRATION, AND THAT THIS ARBITRATION CLAUSE CONSTITUTES A WAIVER OF
EXECUTIVE'S RIGHT TO A JURY TRIAL AND RELATES TO THE RESOLUTION OF ALL DISPUTES
RELATING TO ALL ASPECTS OF THE EMPLOYER/EXECUTIVE RELATIONSHIP, INCLUDING BUT
NOT LIMITED TO, THE FOLLOWING CLAIMS:

                     (i) ANY AND ALL CLAIMS FOR WRONGFUL DISCHARGE OF
EMPLOYMENT; BREACH OF CONTRACT, BOTH EXPRESS AND IMPLIED; BREACH OF THE COVENANT
OF GOOD FAITH AND FAIR DEALING, BOTH EXPRESS AND IMPLIED; NEGLIGENT OR
INTENTIONAL INFLICTION OF EMOTIONAL DISTRESS; NEGLIGENT OR INTENTIONAL
MISREPRESENTATION; NEGLIGENT OR INTENTIONAL INTERFERENCE WITH CONTRACT OR
PROSPECTIVE ECONOMIC ADVANTAGE; AND DEFAMATION.

                     (ii) ANY AND ALL CLAIMS FOR VIOLATION OF ANY FEDERAL, STATE
OR MUNICIPAL STATUTE, INCLUDING, BUT NOT LIMITED TO, TITLE VII OF THE CIVIL
RIGHTS ACT OF 1964, THE CIVIL RIGHTS ACT OF 1991, THE AGE DISCRIMINATION IN
EMPLOYMENT ACT OF 1967, THE AMERICANS WITH DISABILITIES ACT OF 1990, THE FAIR
LABOR STANDARDS ACT, THE CALIFORNIA FAIR EMPLOYMENT AND HOUSING ACT, AND LABOR
CODE SECTION 201, et seq;

                     (iii) ANY AND ALL CLAIMS ARISING OUT OF ANY OTHER LAWS AND
REGULATIONS RELATING TO EMPLOYMENT OR EMPLOYMENT DISCRIMINATION.

       16. No Oral Modification, Cancellation or Discharge. This Agreement may
only be amended, canceled or discharged in writing signed by Executive and the
Chief Executive Officer.

       17. Withholding. The Company shall be entitled to withhold, or cause to
be withheld, from payment any amount of withholding taxes, required by law with
respect to payments made to Executive in connection with him employment
hereunder.

       18. Governing Law. This Agreement shall be governed by the laws of the
State of California.

       19. Effective Date. This Agreement is effective upon the Promotion
Commencement Date.



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       20. Acknowledgment. Executive acknowledges that he has had the
opportunity to discuss this matter with and obtain advice from him private
attorney, has had sufficient time to, and has carefully read and fully
understands all the provisions of this Agreement, and is knowingly and
voluntarily entering into this Agreement.

       IN WITNESS WHEREOF, the undersigned have executed this Agreement:

/s/ P. PLEWMAN                          12/1/99
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(Name)                                  Date
diaDexus

/s/ MOHAN S. IYER                       12/1/99
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Mohan Iyer                              Date
Executive



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