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Exhibit 10.4

                 SIXTH AMENDMENT TO AMENDED AND RESTATED BINDING
                                   TERM SHEET

            This SIXTH AMENDMENT TO AMENDED AND RESTATED BINDING TERM SHEET
(this "AMENDMENT") is made effective as of July 26, 2005 by and between
NORTHWEST BIOTHERAPEUTICS, INC., a Delaware corporation (the "COMPANY"), and
TOUCAN CAPITAL FUND II, L.P., a Delaware limited partnership ("TOUCAN").

                                    RECITALS

      WHEREAS, the Company and Toucan are party to that certain Binding
Convertible Preferred Stock Term Sheet originally dated April 26, 2004 and
amended and restated on October 22, 2004 as further amended on December 27,
2004, January 26, 2005, April 12, 2005, May 13, 2005 and June 16, 2005 (the
"CONVERTIBLE PREFERRED STOCK TERM SHEET").

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      WHEREAS, concurrently herewith, the Company and its affiliates, if any,
and Toucan and its designees, are entering into Amendment No. 8 (the "EIGHTH
AMENDMENT") to that certain Amended and Restated Recapitalization Agreement by
and between the parties thereto; and

      WHEREAS, in connection with the Eighth Amendment, the Company and Toucan
desire to amend the Convertible Preferred Stock Term Sheet as provided herein.

                                    AGREEMENT

      NOW, THEREFORE, for and in consideration of good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Company and Toucan agree as follows:

      1. The paragraph of the Convertible Preferred Stock Term Sheet entitled
"Subsequent Closings:" is hereby amended by replacing the phrase "12 months
after the First Closing" with "December 31, 2006 (or such later date as is
mutually agreed by the parties hereto)" in the first sentence thereof.

      2. The paragraph of the Convertible Preferred Stock Term Sheet entitled
"Warrants:" is hereby amended and restated in its entirety as follows:

      "The Company shall issue $4.85 million in warrant coverage on the first
      $4.85 million Convertible Preferred Stock purchased for cash (the
      "Preferred Stock Warrants"). Preferred Stock Warrants shall not be issued
      upon conversion of notes, exercise of warrants, or other conversion or
      exercise. The number of warrants to be so issued shall be determined on
      the basis of $0.10 per share. If the total of $4.85 million is invested in
      Convertible Preferred Stock, the number of warrants issued shall be
      exercisable for 48.5 million shares of Convertible Preferred Stock. The
      exercise price of such Preferred Stock Warrants shall be $.04 per share
      (subject to adjustment for stock splits, stock dividends and the like).
      The exercise period shall commence upon issuance of the Preferred Stock
      Warrants, and shall continue for a period of seven (7) years after their
      respective issuance dates."

      3. Unless specifically modified or changed by the terms of this Amendment,
all terms and conditions of the Convertible Preferred Stock Term Sheet shall
remain in effect and shall apply fully as described and set forth in the
Convertible Preferred Stock Term Sheet.

      4. This Amendment may be executed in two or more counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

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      The Company and Toucan have executed this SIXTH AMENDMENT TO AMENDED AND
RESTATED BINDING TERM SHEET as of the day and year first written above.

      TOUCAN CAPITAL FUND II, L.P.              NORTHWEST BIOTHERAPEUTICS, INC.

      By: __________________________            By: ____________________________
      Name:                           Linda Powers
      Name:  Alton L. Boynton
      Title:                          Managing Director
      Title:  President

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