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                                                                    EXHIBIT 4.04



                              STANDSTILL AGREEMENT


        This Standstill Agreement (the "Agreement") is made as of April 8, 1999
by and between Corixa Corporation, a Delaware corporation, with a principal
office located at 1124 Columbia Street, Suite 200, Seattle, Washington 98104
(the "Company") and Castle Gate, L.L.C., a Washington limited liability company,
with a principal office located at 2365 Carillon Point, Kirkland, Washington
98033 ("Investor").

                                    RECITALS

        The Company and Investor are parties to that certain Equity Line of
Credit and Securities Purchase Agreement dated as of an even date herewith (the
"Purchase Agreement") pursuant to which Investor has committed to provide to the
Company a two-year line of credit in the aggregate amount of $50,000,000 and the
Company will issue and sell up to 50,000 shares of Series A Preferred Stock of
the Company and certain warrants to purchase shares of common stock of the
Company to Investor. In connection with the execution of the Purchase Agreement,
Investor desires to make certain covenants to the Company, and the Company
desires that Investor make such covenants, so as to provide limits on Investor's
ownership of capital stock of the Company other than pursuant to the Purchase
Agreement.

        In consideration of the foregoing and the mutual promises contained in
this Agreement, the parties agree as follows:

                                    AGREEMENT

        1.     DEFINITIONS.

        For the purposes of this Agreement, the following words and phrases
shall have the following meanings:

               (a) "Affiliate" of an entity means, for so long as one of the
following relationships is maintained, any individual, corporation or other
business entity owned, owning or under common ownership with a party to this
Agreement to the extent of at least fifty percent (50%) of the equity having the
power to vote on or direct the affairs of the entity and any person, firm,
partnership, corporation or other entity actually controlled by, controlling or
under common control with a party to this Agreement.

               (b) "Investor Group" means Investor and its Affiliates.

               (c) "13D Group" means any group of persons formed for the purpose
of acquiring, holding, voting or disposing of Voting Securities which would be
required under the Securities Exchange Act of 1934, as amended (the "Exchange
Act") and the rules and regulations promulgated thereunder, to file a statement
on Schedule 13D with the Securities and Exchange Commission as a "person" within
the meaning of Section 13(d)(3) of the Exchange Act if such group beneficially
owned sufficient securities to require such a filing under the Exchange Act.
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               (d) "Purchase Agreement Securities" means all the Securities (as
such term in defined in the Purchase Agreement) to be issued and sold to
Investor by the Company pursuant to the Purchase Agreement including capital
stock of the Company that may be issued with respect to such Securities pursuant
to the terms and conditions of the Certificate of Designation (as defined in the
Purchase Agreement).

               (e) "Voting Security" means, as of the date of determination, the
Common Stock of the Company, any other security generally entitled to vote for
the election of directors and any outstanding convertible securities, options,
warrants or other rights which are convertible into or exchangeable or
exercisable for securities entitled to vote for the election of directors.

        2.     STANDSTILL OBLIGATIONS.

               (a) LIMITATION. At any time following the date of this Agreement,
except with the prior written consent of the Company's Board of Directors
(excluding the vote of any director representing, employed by or otherwise
affiliated with any member of the Investor Group), no member of the Investor
Group shall, directly or indirectly, acquire any Voting Securities which are not
also Purchase Agreement Securities, except by way of (i) stock splits, stock
dividends or other distributions or offerings made available to holders of
Voting Securities generally, or (ii) stock options, warrants, or other rights to
purchase Voting Securities approved by the Board of Directors of the Company
(excluding the vote of any director representing, employed by or otherwise
affiliated with any member of the Investor Group).

               (b) PARTICIPATION. Except with the prior written consent of the
Company's Board of Directors, the Investor Group will not (i) solicit proxies in
respect of any Voting Securities, (ii) become a "participant" or "participant in
a solicitation", as those terms are defined in Rule 14a-11 under the Exchange
Act, in opposition to a solicitation by the Company, (iii) form or join any
group for the purpose of voting, purchasing or disposing of Voting Securities,
or (iv) deposit any Voting Securities in a voting trust or subject them to a
voting agreement or other arrangement of similar effect, except as contemplated
by this Agreement; provided, however, that the Investor Group shall not be
deemed to be a "participant" or to have become engaged in a solicitation
hereunder solely by reason of (I) the membership of an individual representing,
employed by or otherwise affiliated with any member of the Investor Group on the
Board of Directors, (II) the voting of the Investor Group's Voting Securities in
any election of such representative of the Investor Group to the Board of
Directors, or (III) the Company's solicitation of proxies in connection with any
annual meeting of the stockholders of the Company.

        3.     EXCEPTION FOR CERTAIN THIRD-PARTY ACQUISITIONS.

               (a) EXCEPTION TO STANDSTILL OBLIGATION. Notwithstanding Section
2(a) but subject to Section 4, the Investor Group may acquire Voting Securities
without regard to the limitations set forth above if any of the following events
shall occur:

                      (i) TENDER OR EXCHANGE OFFER. If a bona fide tender or
exchange offer is made by any person or 13D Group (other than an Affiliate of,
or any person acting in concert with, any member of the Investor Group) to
acquire Voting Securities which, if added to



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the Voting Securities (if any) already owned by such person or 13D Group, would
represent ownership of Voting Securities greater than the total number of shares
of Purchase Agreement Securities; or

                      (ii) NONPUBLIC TRANSACTIONS. If it is publicly disclosed
or Investor otherwise learns that Voting Securities representing more than the
total number of shares of Purchase Agreement Securities have been acquired in a
nonpublic transaction or that a bona fide offer has been made to acquire such
securities in a nonpublic transaction by any person or 13D Group (other than an
Affiliate of, or any person acting in concert with, any member of the Investor
Group).

               (b) COMPETING OFFERS. If any event identified in Section 3(a)
occurs, the Investor Group shall be permitted to take such action and make such
offers as may be considered to be of the same nature and type of action or offer
and directed to the same person or persons and for the same resulting number of
shares as that which is being taken by such person or 13D Group; provided that
the Investor Group may only acquire that number of shares which when added to
the number of shares already owned by the Investor Group shall not exceed the
number of shares acquired or to be acquired (assuming any offers to purchase
have been consummated) by such person or 13D Group. In proceeding with any
action or offer permitted under this Section 3(b), the Investor Group shall be
permitted to offer more favorable terms such as price, cash versus securities or
other such terms as may be consistent with an offer of the same nature and type
of consideration as that which is being proposed by such person or 13D Group.

               For example (but without limitation):

                      (i) TENDER OFFER. If a person or 13D Group makes a bona
fide public tender offer for all of the Company's outstanding shares, the
Investor Group may similarly tender for all of the outstanding shares of the
Company.

                      (ii) NONPUBLIC TRANSACTION. If any person or 13D Group
holding less than the total number of shares of Purchase Agreement Securities
proposes to the Board of Directors of the Company to acquire directly from the
Company shares equal to a specified number of Voting Securities in excess of the
total number of shares of Purchase Agreement Securities, the Investor Group may
make a similar proposal to acquire directly from the Company an additional
number of shares that would, if accepted, increase its ownership of Voting
Securities to be equal to the specified number of Voting Securities.

        4.     RESTRICTIONS.

               (a) HART-SCOTT-RODINO. Prior to any acquisition of any Voting
Securities pursuant to Section 3, the Company and the Investor shall consult
with each other pursuant to the terms of Section 5(d) of the Purchase Agreement
as to whether any applications and/or documents may be required to be executed
and filed under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as
amended ("HSR") in connection with such acquisition of Voting Securities and
shall mutually agree on an appropriate cause of action with respect to the
foregoing. In the event the Company and the Investor mutually agree that the
filing of



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applications and/or documents are required under HSR, then no acquisition of
Voting Securities pursuant to Section 3 shall take place until the expiration or
early termination of any notice periods required under HSR with respect to the
filing of such applications and/or documents.

               (b) NASDAQ RULE 4460(i). So long as the Company's Common Stock is
listed for trading on the Nasdaq National Market or an exchange or quotation
system with a rule substantially similar to Rule 4460(i) of the Rules and
Regulations of the National Association of Securities Dealers, Inc., then any
acquisition of Voting Securities pursuant to Section 3 shall be subject to the
conditions set forth in Section 5(l) of the Purchase Agreement.

        5.     MISCELLANEOUS.

               (a) EQUITABLE RELIEF. The Parties acknowledge and agree that
irreparable damage would occur in the event any of the provisions of this
Agreement were not performed in accordance with their specific terms or were
otherwise breached. Accordingly, it is agreed that the parties shall be entitled
to an injunction or injunctions to prevent or cure breaches of the provisions of
this Agreement and to enforce specifically the terms and provisions of this
Agreement in any court of the United States or any state thereof having
jurisdiction, in addition to any other remedy to which they may be entitled in
law or in equity.

               (b) WAIVER. The failure of either party to assert a right
hereunder or to insist upon compliance with any term or condition of this
Agreement shall not constitute a waiver of that right or excuse a similar
subsequent failure to perform any such term or condition by the other party.
None of the terms, covenants and conditions of this Agreement can be waived
except by the written consent of the party waiving compliance.

               (c) AMENDMENTS AND WAIVERS. Any term of this Agreement may be
amended or waived only with the written consent of the parties or their
respective successors and assigns. Any amendment or waiver effected in
accordance with this Section 5(c) shall be binding upon the parties and their
respective successors and assigns.

               (d) ASSIGNMENT. This Agreement may not be assigned by either
party without the prior written consent of the other, except that the Company
may assign this Agreement to a party which acquires all or substantially all of
the Company's assets, whether by merger, sale of assets or otherwise. A merger
or consolidation shall be deemed to constitute an assignment. Subject to the
foregoing, the terms and conditions of this Agreement shall inure to the benefit
of and be binding upon the respective successors and assigns of the parties.
Nothing in this Agreement, express or implied, is intended to confer upon any
party other than the parties hereto or their respective successors and assigns
any rights, remedies, obligations, or liabilities under or by reason of this
Agreement, except as expressly provided in this Agreement.

               (e) GOVERNING LAW; JURISDICTION. This Agreement and all acts and
transactions pursuant hereto and the rights and obligations of the parties
hereto shall be governed, construed and interpreted in accordance with the laws
of the State of Washington, without giving effect to principles of conflicts of
law. Each of the parties to this Agreement



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consents to the exclusive jurisdiction and venue of the courts of the state and
federal courts of King County, Washington.

               (f) COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall constitute one instrument.

               (g) TITLES AND SUBTITLES. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

               (h) NOTICES. Any notice required or permitted by this Agreement
shall be in writing and shall be deemed sufficient upon receipt, when delivered
personally or by courier, overnight delivery service or confirmed facsimile, or
forty-eight (48) hours after being deposited in the regular mail as certified or
registered mail (airmail if sent internationally) with postage prepaid, if such
notice is addressed to the party to be notified at such party's address or
facsimile number as set forth below, or as subsequently modified by written
notice, and if to Company, to William W. Ericson, Venture Law Group, 4750
Carillon Point, Kirkland, Washington 98033, and if to the Investor, to Mark
Beatty, Preston Gates & Ellis, 701 Fifth Avenue, #5000, Seattle, Washington
98104.

               (i) SEVERABILITY. If one or more provisions of this Agreement are
held to be unenforceable under applicable law, the parties agree to renegotiate
such provision in good faith, in order to maintain the economic position enjoyed
by each party as close as possible to that under the provision rendered
unenforceable. In the event that the parties cannot reach a mutually agreeable
and enforceable replacement for such provision, then (i) such provision shall be
excluded from this Agreement, (ii) the balance of the Agreement shall be
interpreted as if such provision were so excluded and (iii) the balance of the
Agreement shall be enforceable in accordance with its terms.

               (j) ATTORNEY'S FEES. If any action at law or in equity is
necessary to enforce or interpret the terms of this Agreement, the prevailing
party shall be entitled to reasonable attorney's fees, costs and necessary
disbursements in addition to any other relief to which such party may be
entitled.

               (k) ENTIRE AGREEMENT. This Agreement is the product of both of
the parties hereto, and constitutes the entire agreement between such parties
pertaining to the subject matter hereof, and merges all prior negotiations and
drafts of the parties with regard to the transactions contemplated herein. Any
and all other written or oral agreements existing between the parties hereto
regarding such transactions are expressly canceled.



                            [Signature Page Follows]



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        The parties have caused this Standstill Agreement to be duly executed
and delivered by their proper and duly authorized officers as of the day and
year first written above.

                                        COMPANY:

                                        CORIXA CORPORATION


                                        By: /s/ Steven Gillis
                                            ------------------------------------
                                            Steven Gillis, Chief Executive
                                            Officer

                                        Address: 1124 Columbia Street, Suite 200
                                                 Seattle, Washington 98104

                                        Facsimile Number: (206) 754-5762


                                        INVESTOR:

                                        CASTLE GATE, L.L.C.


                                        By:    /s/ Michael Larson
                                            ------------------------------------

                                        Name:  Michael Larson
                                              ----------------------------------

                                        Title:   Business Manager
                                               ---------------------------------

                                        Address:    2365 Carillon Point
                                                --------------------------------
                                                    Kirkland, WA 98033
                                        ----------------------------------------

                                        Facsimile Number:   (425) 889-0288



                     SIGNATURE PAGE TO STANDSTILL AGREEMENT