CONVERSION
AGREEMENT





This Agreement is entered into,
effective as of September 28, 2009 (the “Effective Date”), by and between
Northwest Biotherapeutics (“NWBT” or “the Company”), a Delaware corporation with
its headquarters in Bethesda, Maryland, Toucan Capital Fund II, a Delaware
limited liability company (“Toucan Capital”) with offices in Bethesda, Maryland,
and Toucan Partners (“Toucan Partners”), a Delaware limited liability company
with offices in Bethesda, Maryland.





WHEREAS, Toucan Partners provided a
loan of $1 million to the Company pursuant to that certain Note and Loan
Agreement dated as of August 19, 2008 (the “August 08 TP Loan”), with an annual
interest rate of twelve percent (12%), a default interest rate of fifteen
percent (15%) and a maturity of six (6) months;





WHEREAS, the August 08 TP Loan was due
to be repaid on February 19, 2009, but has not been repaid to date, due to
resource limitations at the Company;





WHEREAS, Toucan Partners provided a
loan of $500,000 pursuant to that certain Note and Loan Agreement dated as of
December 22, 2008 (the “December 08 TP Loan”), with an annual interest rate of
twelve percent (12%), a default interest rate of fifteen percent (15%), a
maturity of six (6) months, and certain warrant coverage;





WHEREAS, the December 08 TP Loan was
due to be repaid on May 22, 2009, but has not been repaid to date, due to
resource limitations at the Company;





WHEREAS, certain other investors
provided loans to the Company during late October and November 2008 (the
“November 08 Investor Loans”), with an annual interest rate of twelve percent
(12%), a default interest rate of fifteen percent (15%), a maturity of six (6)
months and warrant coverage of fifty percent (50%);





WHEREAS, the Company desires to have
the August 08 Loan and the December 08 Loan be converted into equity of the
Company instead of being repaid in cash, in order to conserve the Company’s
resources;





WHEREAS, Toucan Partners is willing to
convert the August 08 Loan and the December 08 Loan into equity of the Company,
instead of receiving repayment in cash, on the terms and conditions set forth in
this Agreement;





WHEREAS, both Toucan Capital and Toucan
Partners, and their affiliates, successors and assigns (all such parties of any
type, existing as of the date hereof or at any time hereafter, collectively, the
“Toucan Parties”) beneficially own, hold or control, directly or indirectly, a
large number of warrants exercisable for common stock of the Company, with
varying exercise prices and varying exercise periods (collectively, the “Toucan
Parties’ Warrants”);








NOW THEREFORE, in consideration of the
premises and covenants set forth herein, and good and valid consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereby
agree as follows:





1.    NOTE
CONVERSION





All
principal and interest (including default interest) pursuant to the August 08 TP
Loan and the December 08 TP Loan shall be converted into common stock of the
Company, at the price of $0.20 (twenty cents) per share, as of the Effective
Date of this Agreement.





2.  WARRANT
COVERAGE AND EXERCISE PERIODS





With
respect to all Toucan Parties’ Warrants, each specified or otherwise applicable
exercise period is hereby extended for three (3) years beyond the expiration
dates currently specified or otherwise applicable for the respective exercise
periods of all such Toucan Parties’ Warrants.  With respect to the
December 08 TP Loan, the warrant coverage is hereby conformed to the fifty
percent (50%) warrant coverage provided under the terms of the November 08
Investor Loans, and is specified to be fifty percent (50%) coverage for the
December 08 TP Loan, with the same forty-one cent ($0.41) exercise price as the
warrants relating to the November 08 Investor Loans.





3.  REPRESENTATIONS
AND WARRANTIES





3.1   Organization,
Authority.   The Company represents that it is a
corporation duly organized, validly existing and in good standing under the laws
of its jurisdiction of organization, with all necessary corporate power and
authority to enter into this Agreement, and to perform its obligations
hereunder.





3.2   Authorization, Binding
Agreement.   Each party represents that this Agreement has
been duly authorized by all necessary corporate or other action, this Agreement
has been duly executed and delivered by such party, and this Agreement
constitutes a legal, valid and binding obligation of such party, enforceable
against him, her or it in accordance with its terms.





4.   MISCELLANEOUS





4.1    Entire
Agreement.  This Agreement supersedes all prior agreements or
understandings, written or oral, between the parties or relating to the subject
matter hereof, and incorporates the entire understanding of the parties with
respect thereto.





4.2    Amendment,
Waiver.  This Agreement may be amended or supplemented only by
a written instrument signed by both parties.  The party benefited by
any condition or obligation may waive the same, but such waiver shall not be
enforceable by another party unless made by written instrument signed by the
waiving party.





4.3     Severability.  In
the event that any provision of this Agreement is determined to be invalid or
unenforceable in whole or in part, all other provisions of this Agreement shall
remain in full force and effect, and the parties will cooperate, in good faith,
and use best efforts to achieve as nearly as possible the same results as would
have been obtained under the provision that was determined to be invalid or
unenforceable.





4.4     
 Notices.  Any
notice under or relating to this Agreement shall be given in writing, and shall
be deemed sufficiently given and served for all purposes upon delivery, when
delivered personally, or by facsimile with confirmed transmission report, or by
nationally recognized courier service, or by United States registered or
certified mail.





4.5  
    Successors and
Assigns.  This Agreement shall be binding upon and inure to the
benefit of the heirs, successors and assigns of the parties hereto.





4.6  
    Counterparts.  This
Agreement may be executed in any number of counterparts. Each such executed
counterpart shall be deemed to be an original instrument, and all such executed
counterparts together shall constitute one and the same instrument.





4.7   
   Governing Law,
Jurisdiction.  This Agreement shall be construed in accordance
with, and governed by the laws of, the State of Delaware, excluding the
application of its choice of law rules.  The parties consent to the
exclusive jurisdiction of the state or Federal courts in Delaware, in connection
with any action arising out of or relating to this Agreement, and agree that
such venue is proper.





[signatures
on following page]







IN
WITNESS WHEREOF, the parties have executed this Asset Purchase Agreement as of
the date first set forth above.




NORTHWEST
      BIOTHERAPEUTICSBy:Name:Title:TOUCAN
      PARTNERSBy:Name:Title:TOUCAN
      CAPITALBy:Name:Title: