RETENTION AND CONVERSION
AGREEMENT
 
 This Agreement is entered into,
effective as of September 28, 2009,  by and between Northwest
Biotherapeutics (“NWBT” or “the Company”), a Delaware corporation with its
headquarters in Bethesda, Maryland, and Dr. Alton Boynton (“Dr. Boynton”), a
resident of Kingston, Washington.
 
 WHEREAS, Dr. Boynton was the scientific
founder of the Company and has been serving as President and Chief Executive
Officer of the Company since 2003;
 
 WHEREAS, the Company is raising a
series of financings, and plans to expand its operations and its management
team;
 
 WHEREAS, the Company desires to retain
the services of Dr. Boynton either as Chief Executive Officer (CEO) or as Chief
Scientific Officer (CSO), and Dr. Boynton is willing to provide such services,
for a period of one year, through September 30, 2010;
 
 WHEREAS, the Company also desires to
provide to Dr. Boynton, and Dr. Boynton desires to receive, an opportunity to
receive a certain portion of his salary in the form of stock as provided
herein;
 
 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.     RETENTION
PERIOD
 
 The
retention period covered by this agreement is from September 28, 2009, through
September 30, 2010 (the “Retention Period”).  All provisions of this
Agreement are conditional upon Dr. Boynton continuing his employment throughout
the Retention Period, and devoting his full time, good faith efforts to the
position of CEO or CSO as elected by the Company, provided, however, that the
provisions of this Agreement shall cease to be conditional upon Dr. Boynton
continuing his employment during the then remaining portion of the Retention
Period if (a) the Company terminates Dr. Boynton’s employment without cause, (b)
the Company makes Dr. Boynton’s continued employment as either Chief Executive
Officer (“CEO) or Chief Scientific Officer (“CSO”) effectively infeasible or
impracticable, or (c) Dr. Boynton becomes unable to work due to medical reasons,
and does not enter into any competing employment, consulting or other business
arrangement.
 
 2.    RETENTION
PERIOD ROLE
 
 Pursuant
to this Agreement, Dr. Boynton will serve as either the CEO or CSO of the
Company, at the Company’s election (as determined by the Chairperson) any time
during the Retention Period, in the Company’s sole discretion, notwithstanding
any prior or other employment agreement, arrangement or
understanding.
  
 
 3.    RETENTION
PERIOD COMPENSATION
 
 Upon
execution of this Agreement, the Company will pay to Dr. Boynton a bonus equal
to seventy-five thousand dollars ($75,000) (the “Retention
Bonus”).  Such Retention Bonus will be paid in the form of a
convertible note, attached hereto as Exhibit
A.  Dr. Boynton will elect, on or before November 1, 2009, one
of three alternative structures for the convertible note:  (a) payment
in cash;  (b) payment in common stock of the Company at the same price
per share as the New Funding now being received by the Company ($0.20 per
share), with the taxes being paid by Dr. Boynton and the amount of the common
stock being equal to the full gross amount of the retention bonus, or (c)
payment in common stock of the Company at $0.20 per share, with the taxes being
paid by the Company and the amount of the common stock being equal to the net
after-tax amount of the Retention Bonus.
 
 4.    SALARY
CONVERSION
 
 With
respect to any semi-monthly salary payments payable to Dr. Boynton during
October through December, 2009 (the “Conversion Period”), Dr. Boynton may elect,
by written notification to the Company, to receive up to the equivalent of four
(4) such salary payments (the “Maximum Conversion Amount”) in the form of common
stock of the Company instead of in cash.  Dr. Boynton may exercise
this conversion election with respect to all or any portion of each semi-monthly
salary amount during the Conversion Period up to the Maximum Conversion Amount.
The conversion price per share, for any such salary payments to be received in
stock, will be twenty cents ($0.20) per share.
 
 5.  EXTENSION OF
OPTIONS
 
 With
respect to all warrants and options beneficially owned, held or controlled by or
on behalf of Dr. Boynton (whether or not vested in whole or in part), the
exercise period currently applicable to each such warrant and option is hereby
amended so as to be extended by three (3) years from the date currently
specified for each exercise period, respectively, to expire.
 
 6.  REPRESENTATIONS
AND WARRANTIES
 
 6.1   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.
 
 6.2   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.
  
 
 7.   MISCELLANEOUS
 
 7.1    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.
 
 7.2    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.
 
 7.3     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.
 
 7.4        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.
 
 7.5        Successors and
Assigns.  This Agreement shall be binding upon and inure to the
benefit of the heirs, successors and assigns of the parties hereto.
 
 7.6        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.
 
 7.7        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:DR.
      ALTON BOYNTONBy:Name:Title: