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                                                                    Exhibit 10.1

                       SECOND AMENDMENT TO LOAN AGREEMENT

         This SECOND AMENDMENT (this "Second Amendment") to the certain Loan
Agreement by and between COULTER PHARMACEUTICAL, INC. (the "Borrower"), a
Delaware corporation and a wholly owned subsidiary of CORIXA CORPORATION, a
Delaware corporation ("Corixa"), and SMITHKLINE BEECHAM CORPORATION, a
Pennsylvania corporation ("Lender") dated October 23, 1998 (the "Loan
Agreement"), as amended by the first amendment dated June 28, 2002 (the "First
Amendment" and together with the Loan Agreement, the "Amended Loan Agreement"),
is made on August 26, 2003. Except as otherwise defined in this Second
Amendment, capitalized terms used herein shall have the meaning ascribed to them
in the Amended Loan Agreement.

         WHEREAS, the Amended Loan Agreement provides that Borrower, at its
discretion, may repay the Loan in cash or shares of Corixa common stock;

         WHEREAS, the Amended Loan Agreement provides that, if Borrower elects
to repay the Loan in shares of Corixa common stock, such shares must be issued
pursuant to an effective registration statement under the Securities Act of
1933, as amended (the "Securities Act"); and

         WHEREAS, Borrower desires to provide Lender with certain registration
rights to facilitate the resale by Lender of shares of Corixa common stock
issued to Lender pursuant to the Amended Loan Agreement in a manner consistent
with the requirements of the Securities Act.

         NOW THEREFORE, in consideration of the mutual promises contained
herein, the receipt and sufficiency of which is hereby acknowledged, and
intending to be legally bound hereby, the parties hereto agree as follows:

         1. Section 2(b). Section 2(b) to the Amended Loan Agreement is hereby
deleted and the following shall be substituted therefor:

                  (b) PRINCIPAL PAYMENTS. (i) In the event that Borrower's
                  EBITDA for the twelve (12) month period ending September 30,
                  2001 exceeds U.S. $15,000,000, then on the date that is
                  thirty-six (36) months after the Effective Date, Borrower
                  shall make a principal payment of an amount equal to
                  thirty-three percent (33.0%) of then outstanding principal
                  balance of the Loans; (ii) in the event that Borrower's EBITDA
                  for the twelve (12) month period ending September 30, 2002
                  exceeds U.S. $15,000,000, then on the date that is forty-eight
                  (48) months after the Effective Date, Borrower shall make a
                  principal payment of an amount equal to fifty percent (50.0%)
                  of then outstanding principal balance of the Loans; and (iii)
                  Borrower shall repay the entire outstanding unpaid principal
                  balance of the Loans, together with all accrued unpaid
                  interest thereon, on the Maturity Date. At Borrower's option
                  under this Section 2(b), principal payments, together with all
                  accrued unpaid interest thereon, may be paid in cash or the
                  number of shares (the "Shares") of common stock, $0.001 par
                  value per share, of Corixa (the "Common Stock") determined by
                  dividing (i) the amount of principal and interest to be repaid
                  by (ii) the Share Price (as hereinafter defined). The "Share
                  Price" shall be the closing price of Common Stock on the
                  Nasdaq National Market, as
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                  reported by the Wall Street Journal, Western Edition (the
                  "Wall Street Journal"), on the last trading day preceding the
                  day on which Borrower elects to repay the Loan (the "Repayment
                  Date"). In the event the number of Shares so calculated would
                  include a fraction of a Share, the number of Shares shall be
                  decreased to the nearest whole number of Shares and the
                  balance of the amount to be repaid shall be paid in cash.

         2. Section 2(c). Section 2(c) to the Amended Loan Agreement is hereby
deleted and the following shall be substituted therefor:

                  (c) PREPAYMENTS. Borrower may prepay the Loan in (i) cash or
                  (ii) the number of Shares determined by dividing (y) the
                  amount of principal and interest to be repaid by (z) the Share
                  Price, at any time (including, without limitation, upon the
                  occurrence of an Event of Default) in full, or in part, in
                  minimum amounts of U.S. $100,000. In the event the number of
                  Shares so calculated would include a fraction of a Share, the
                  number of Shares shall be decreased to the nearest whole
                  number of Shares and the balance of the amount to be repaid
                  shall be paid in cash.

         3. Section 2(d). The following shall be added to the Amended Loan
Agreement as Section 2(d).

                  (d) REGISTRATION OF SHARES. If Borrower elects to repay the
                  Loan in Shares as permitted provided in the this Section 2,
                  then Corixa shall register the resale of the Shares by Lender
                  on the terms and conditions of the Registration Rights
                  Agreement dated as of August 26, 2003, by and among Corixa,
                  Borrower and Lender.

         4. Entire Agreement. This Second Amendment and the Amended Loan
Agreement constitute and contain the entire agreement and understanding of the
parties with respect to the subject matter hereof, and also supersede any and
all prior negotiations, correspondence, agreements or understandings with
respect to the subject matter hereof.

         5. Miscellaneous. All the terms, provisions and conditions of the Loan
Documents not amended by this Second Amendment shall be and remain the same and
in full force and effect.

                            [Signature page follows.]




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         IN WITNESS WHEREOF, the parties hereto have executed this Second
Amendment as of the date and year first above written.

                                       COULTER PHARMACEUTICAL, INC.

                                       By:  /s/ Michelle Burris
                                           -------------------------------------
                                       Name:    Michelle Burris
                                             -----------------------------------
                                       Title:  C.F.O.
                                              ----------------------------------



                                       CORIXA CORPORATION

                                       By:  /s/ Michelle Burris
                                           -------------------------------------
                                       Name:    Michelle Burris
                                             -----------------------------------
                                       Title:  Sr. V.P. & C.F.O.
                                              ----------------------------------



                                       SMITHKLINE BEECHAM CORPORATION

                                       By:  /s/ Donald F. Parman
                                           -------------------------------------
                                       Name:    Donald F. Parman
                                             -----------------------------------
                                       Title:  Vice President and Secretary
                                              ----------------------------------




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