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                                                                 Exhibit 10.29



                            THIRD AMENDMENT TO LEASE
                          --------------------------

         THIS THIRD AMENDMENT TO LEASE ("Amendment") is made effective as of the
24th day of February, 2000, between The Metcalf Family Living Trust Dated June
11, 1993 (as "Landlord") and Onyx Pharmaceuticals, Inc., a Delaware corporation
(as "Tenant"), with reference to the following facts.

                                    RECITALS

         A. Landlord (through its predecessor-in-interest) and Tenant are
parties to that certain "Lease" dated as of September 9, 1992 (the "Original
Lease"), as amended by that certain "First Amendment to Lease", dated April
21, 1993 (the "First Amendment"), and that certain "Second Amendment to
Lease", dated April 23, 1996 (the "Second Amendment"). (The Original Lease,
together with the First Amendment and the Second Amendment are referred to
herein as, collectively, the "Existing Lease". From and after the date
hereof, all references to "the Lease" shall mean the Existing Lease, as
amended by this Amendment.)

         B. The Existing Lease provides for two (2) options to extend, each for
a period of five (5) years. Tenant has exercised the first option to extend
("First Option") and desires to perform certain improvements in the Premises and
to the Building.

         C. Landlord and Tenant now desire to memorialize the terms and
conditions of the First Option and applicable to the proposed improvements.

NOW, THEREFORE, in consideration of the mutual covenants and obligations
contained herein, Landlord and Tenant agrees as follows:

                                    AGREEMENT

1.       RECITALS. The above Recitals are true and correct and are incorporated
herein by this reference.

2.       TERM. The term of the Lease shall be deemed extended for the period of
five (5) years, which constitutes the First Option period. The First Option
period shall commence on May 1, 2000 and shall expire on April 30, 2005.

3.       MINIMUM RENTAL. Minimum Rental for the First Option period shall be as
follows:

<TABLE>

<S>                                 <C>
         5/1/00 - 4/30/01           $52,836/month

         5/1/01 - 4/30/02           $54,421/month

         5/1/02 - 4/30/03           $56,054/month

         5/1/03 - 4/30/04           $57,735/month


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         5/1/04 - 4/30/05           $59,467/month

</TABLE>

4.       TENANT IMPOVEMENTS. Tenant shall be permitted to construct certain
improvements in and on the Premises in accordance with this Lease, including
but not limited to expanded laboratory facilities. Following execution of
this Amendment, Tenant shall prepare and present to Landlord for Landlord's
review and approval (not to be unreasonably withheld or delayed), plans and
specifications for the contemplated improvements (the "Improvements"). Within
ten (10) days after delivery of such plans by Tenant, Landlord shall either
reasonably approve or disapprove such plans by written notice to Tenant, and
if Landlord shall reasonably disapprove such plans, Landlord shall specify
with particularity the reasons therefor. Landlord and its architect and/or
engineer shall reasonably cooperate with Tenant in Tenant's preparation of
plans and specifications for the Improvements. Following approval of plans
and specifications by Landlord, Tenant shall promptly and diligently
undertake and complete, subject to delays for causes beyond its reasonable
control, the Improvements in accordance with the approved plans and
specifications. Such work shall be performed in a neat and workmanlike manner,
shall conform to all applicable governmental codes, laws and regulations in
force at the time such work is complete, shall be performed in a manner that
does not disturb other tenants at the Property and that complies with
Landlord's reasonable rules and regulations, shall be performed by a licensed
contractor satisfactory to Landlord, and shall comply with all other
conditions of Section 7.1 of the Original Lease applicable to alterations or
improvements by Tenant. Tenant shall be responsible for obtaining all
required permits and governmental approvals for its work. For and applicable
only to the actual Improvements constructed, Landlord shall pay the
Construction Allowance, as described in Section 5, hereinbelow.

5.       CONSTRUCTION ALLOWANCE. Landlord shall pay for actual construction of
the Improvements, a sum not to exceed Five Hundred Sixty-eight Thousand One
Hundred Twenty-eight Dollars ($568,128) ("Construction Allowance"), as
follows:

         (a) Prior to any request for payment, Tenant shall have approved the
status of construction of the Improvements and satisfied itself that the work
is complete to that point, provided however, Landlord shall have the right to
inspect and approve any and all roof construction/installation, such approval
not to be unreasonably withheld or delayed;

         (b) Tenant shall forward to Landlord the contractor's request for
payment along with Tenant's approval of the work. Payment by Landlord (which may
include payments to subcontractors) shall be made directly to the contractor
(or subcontractor, as the case may be) within twenty (20) days after receipt by
Landlord of the documentation required by this Amendment (and, in the case of
any roof work, completion of Landlord's inspection).

         (c) Requests for such payment shall not be submitted more often than
once every two (2) weeks.

         (d) Requests for payment shall be accompanied (i) for the first
payment, by conditional lien releases applicable to the work for which
payment is being requested; (ii)


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for all future payments, by conditional lien releases applicable to the work
for which payment is being requested and unconditional lien releases for all
work for which payment has previously been made. Tenant shall be responsible
for obtaining unconditional lien releases upon Landlord's final payment and
shall record a Notice of Completion with a conformed copy to be forwarded to
Landlord. Failure to do so within thirty (30) days after final payment and
notice to Tenant requesting such Notice of Completion shall constitute a
breach of the Lease.

         (e) In the event that the cost of completion of the Improvements
exceeds the Construction Allowance, the Improvements shall nevertheless be
completed and any excess shall be payable by Tenant.

6.       LEASE REMAINS IN EFFECT. Except as modified by this Amendment, the
Existing Lease remains unchanged and in full force and effect, and specifically,
nothing contained in Section 5 above shall be construed to alter Section 8.1
("Landlord's Work") or Section 8.2 ("Tenant's Obligation for Maintenance") in
the Original Lease.

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Amendment as
of the date first above written.

LANDLORD:                                    TENANT:

THE METCALF FAMILY LIVING                    ONYX PHARMACEUTICALS, INC.,
TRUST DATED JUNE 11, 1993                    a Delaware corporation

By: /s/ David Metcalf                        By: /s/ Judith I. Blakemore
    ------------------------------               ------------------------------
        David Metcalf, Trustee                       Judith I. Blakemore
                                                 ------------------------------
                                            Its:   Chief Operating Officer
                                                 ------------------------------


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