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                                                                   Exhibit 10.76

                       FIRST AMENDMENT TO LEASE AGREEMENT

            This First Amendment to Lease Agreement (the "AMENDMENT") is made as
of this 15th day of January, 2002 between Gateway Boulevard Associates II, LLC,
a California limited liability company ("LANDLORD")and Coulter Pharmaceutical,
Inc., a Delaware corporation ("TENANT").

                                   WITNESSETH

            WHEREAS, Landlord (as successor in interest to HMS Gateway Office,
L.P., a Delaware limited partnership ("HMS")) and Tenant are parties to that
certain Lease Agreement dated May 19, 2000 (the "LEASE"); and

            WHEREAS, pursuant to the terms of Exhibit B to the Lease, Landlord
agreed to provide Tenant with a Tenant's Allowance (as defined in the Lease)
equal to $1,596,593.00 (based on $31.83 multiplied by the Premises Square
Footage (as defined in the Lease)) toward the Tenant Improvement Costs (as
defined in the Lease);

            WHEREAS, Tenant had determined not to complete certain tenant
improvements in the portion of the Premises identified on Exhibit A attached
hereto and made a part hereof which consists of 7,013 square feet (the
"IDENTIFIED PREMISES");

            WHEREAS, Landlord desires for the Identified Premises to be improved
and, subject to the terms and conditions of this Amendment, Landlord and Tenant
have agreed that certain improvements will be constructed within and installed
on the Identified Premises which improvements ("Additional Tenant Improvements")
are in addition to the Tenant Improvements (as that term is defined in the
Lease).

            WHEREAS, Fremont Investment & Loan, a California industrial loan
association ("Fremont") is the holder of a mortgage encumbering Landlord's
interest in the Premises;

            NOW, THEREFORE, for and in consideration of the foregoing recitals
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Landlord and Tenant agree as follows:

            1. Definitions. Capitalized terms used herein and not otherwise
defined shall have the meanings ascribed to such terms in the Lease.

                  (a) ADDITIONAL TENANT IMPROVEMENTS COST means the cost of
completion of the Additional Tenant Improvements and related design,
engineering, and permitting fees, (including, without limitation, the Identified
Premises Design Costs and the Identified Premises Working Drawings Costs) but
excluding the cost of any furniture, trade fixtures or equipment.

                  (b) ATTRIBUTED TENANT'S ALLOWANCE shall mean $223,224.00
(which equals the Tenant's Allowance attributable to the Identified Premises
($31.83 multiplied by 7,013)).

                  (c) CONTINGENCY ALLOWANCE shall mean $57,296.00 (based on
$8.17 multiplied by the square footage contained in the Identified Premises).

            2. Schedule. Tenant shall cause Tenant's Architect to furnish to
Landlord on or before January 31, 2002, space plans and specifications for the
Identified Premises (the "PRELIMINARY


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IDENTIFIED PREMISES PLANS"). Landlord has deposited, or caused to be deposited,
the Attributed Tenant's Allowance and the maximum amount of the Contingency
Allowance into an escrow account with Fremont pursuant to an Escrow and
Depository Agreement (Additional Tenant Improvements) of even date herewith
between Landlord, Fremont and HMS ("Escrow Agreement"). Landlord shall direct
Fremont to disburse and Fremont shall disburse to Tenant's Architect all costs
reasonably incurred in connection with the Preliminary Identified Premises Plans
(the "IDENTIFIED PREMISES DESIGN COSTS"), including any revisions required under
this Amendment out of the Tenant's Allowance or the Contingency Allowance upon
delivery to Landlord and Fremont of Tenant's authorization to pay and invoices,
receipts, and other documents reasonably required to substantiate such costs.

                  (a) The Preliminary Identified Premises Plans shall be subject
to Landlord's approval, which approval shall not be unreasonably withheld,
conditioned, or delayed and such approval or disapproval shall be given within
ten (10) business days after receipt of the Preliminary Identified Premises
Plans. If Landlord disapproves the Preliminary Identified Premises Plans, then
within ten (10) business days thereafter, Landlord shall meet with Tenant's
Architect and Tenant to discuss or shall submit to the Tenant's Architect and
Tenant in writing, the reasons for Landlord's disapproval. Within ten (10)
business days following such meeting or submission, Tenant shall cause the
Tenant's Architect to revise the same and to submit new Preliminary Identified
Premises Plans to Landlord. The same procedure set forth in this paragraph will
be repeated as set forth above until Landlord has approved the Preliminary
Identified Premises Plans.

                  (b) Following Landlord's approval of the Preliminary
Identified Premises Plans, Tenant shall cause Tenant's Architect to prepare
detailed construction drawings and specifications (the "IDENTIFIED PREMISES
WORKING DRAWINGS") for the Tenant Improvements based strictly upon the
Preliminary Identified Premises Plans, except as otherwise agreed in writing by
Landlord and Tenant. The Identified Premises Working Drawings shall be completed
within ten (10) business days after Landlord's approval of the Preliminary
Identified Premises Plans.

                  (c) The Identified Premises Working Drawings shall be subject
to Landlord's approval, which approval shall not be unreasonably withheld,
conditioned, or delayed and such approval or disapproval shall be given by
written notice from Landlord to Tenant within ten (10) business days after
receipt of the Identified Premises Working Drawings. If Landlord disapproves the
Identified Premises Working Drawings, then within ten (10) business days
thereafter, Landlord shall meet with Tenant's Architect and Tenant to discuss,
or shall submit to Tenant's Architect and Tenant in writing, the reasons for
Landlord's disapproval. Within ten (10) business days following such meeting or
submission, Tenant shall cause Tenant's Architect to revise the same and to
submit new Identified Premises Working Drawings to Landlord, and the same
procedure will be repeated as set forth above until Landlord has approved the
Identified Premises Working Drawings in writing (the "APPROVED IDENTIFIED
PREMISES PLANS"). Landlord shall direct Fremont Bank to disburse the reasonable
costs of preparing the Identified Premises Working Drawings, together with any
revisions thereto to Tenant's Architect from the Attributed Tenant's Allowance
and the Contingency Allowance upon delivery to Landlord and Fremont of Tenant's
authorization to pay, invoices, receipts and other documents reasonably required
to substantiate costs. Upon approval of the Identified Premises Working
Drawings, Landlord shall deliver to Tenant a list of Additional Tenant
Improvements to be removed by Tenant, at Tenant's cost and expense in accordance
with Paragraph 11 of the Lease, upon expiration of the Term or earlier
termination of the Lease. Notwithstanding the foregoing, during the preparation
of the Identified Premises Working Drawings, Landlord shall, upon Tenant's
request, advise Tenant of items that will be required to be removed pursuant to
the previous sentence.


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                  (d) Within ten (10) business days after Landlord's approval of
the Approved Identified Premises Plans, Tenant shall cause Contractor to furnish
to Landlord and Tenant a final cost quote for the Additional Tenant Improvements
within the Identified Premises based upon the Approved Identified Premises
Plans. If the Additional Tenant Improvements Cost (when added to any costs
payable by Landlord pursuant to 2(a)-(c) above) is greater than the sum of the
Contingency Allowance and the Attributable Tenant's Allowance, Tenant shall be
responsible for the excess (the "EXCESS COSTS"). Tenant shall enter into a
construction contract with Contractor for the Additional Tenant Improvements
("Contract"), subject to Landlord's approval of the Contract, which approval
shall not be unreasonably withheld or delayed.

                  (e) Tenant hereby agrees to complete construction of the
Additional Tenant Improvements within the Identified Premises on or before the
date that is 120 days after delivery to Tenant of Landlord's written approval of
the Approved Identified Premises Plans.

                  (f) Tenant hereby agrees that if requested by Landlord, HMS
Gateway Office, L.P. may attend any and all meetings with Tenant's Architect and
Tenant as described above.

            3. Payment of Construction Costs. Pursuant to the Contract,
Contractor shall bill Landlord and Tenant directly for progress payments pro
rata in accordance with their respective shares of the costs payable pursuant to
the Contract. Landlord's share of such costs ("Landlord's Share") shall be equal
to the sum of the Attributed Tenant Allowance plus the Contingency Allowance,
minus any sums paid or payable by Landlord to Tenant's Architect pursuant to
paragraph 2 and minus any other sums expended by Landlord at the request of
Tenant for Additional Tenant Improvement Costs. Tenant shall pay all sums
payable under the Contract in excess of Landlord's Share. Landlord shall direct
Fremont to disburse Landlord's pro rata share of progress payments directly to
Contractor upon receipt of (i) Tenant's authorization to pay, (ii) AIA document
G702, Application and Certification for Payment, (iii) invoices or other
supporting documentation reasonably requested by Landlord or Fremont and (iv) a
conditional lien waiver signed by Contractor or subcontractor as to the current
payment. Landlord shall be entitled to suspend or terminate construction of the
Additional Tenant Improvements within the Identified Premises and to declare
Tenant in default in accordance with the terms of the Lease, if payment by
Tenant of Tenant's pro rata share of any progress payment has not been received
by Contractor when due, as required hereunder. Moreover, Landlord shall not be
required to pay or cause Fremont to disburse its pro rata share of any progress
payment until such time as Landlord receives from Contractor an unconditional
lien waiver as to each progress payment that has previously been made and a
conditional lien waiver for the current progress payment. All lien waivers shall
comply with California law regarding materialmen and mechanic's liens. If the
Additional Tenant Improvements Cost is less than the sum of the Attributed
Tenant's Allowance and the Contingency Allowance, such excess shall be returned
to Landlord and HMS pursuant to the Escrow Agreement and Tenant shall have no
rights to such excess.

            4. Construction of Additional Tenant Improvements within the
Identified Premises. All Additional Tenant Improvements within the Identified
Premises shall be constructed and installed in accordance with all of the
provisions of the Lease. Tenant acknowledges that all references to the term
"Approved Plans" in Paragraph C, Paragraph D, and Paragraph E of Exhibit B and
elsewhere in the Lease and the other exhibits to the Lease shall mean and refer
to the Approved Plans and the Approved Identified Premises Plans.

            5. No Removal of Additional Tenant Improvements. Landlord agrees
that in no event shall Tenant be liable for removing the Additional Tenant
Improvements upon the expiration of the Term or earlier termination of the
Lease.


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            6. Landlord's Fees and Costs. Notwithstanding anything to the
contrary contained in the Lease, neither Landlord nor any agent or employee of
Landlord (including, without limitation, any property) shall be entitled to
receive any administration or other fee from Tenant in connection with the
design and construction of the Additional Tenant Improvements or the supervision
thereof and Landlord shall be solely responsible for all costs incurred by
Landlord in connection with such administration and supervision.

            7. Ratification and Confirmation. Landlord and Tenant hereby ratify
and confirm each and every term of the Lease as modified by paragraphs 1 through
6 above.

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

Landlord                                 GATEWAY BOULEVARD ASSOCIATES II, LLC,
                                         a California limited liability company


                                         By:  /s/ PHILLIP H. RAISER
                                         --------------------------------------
                                         Title:  Manager

Tenant:                                  COULTER PHARMACEUTICAL, INC.,
                                         a Delaware corporation

                                         By:  /s/ STEVEN GILLIS
                                         --------------------------------------
                                         Title:  President


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