Document:

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                                                                    EXHIBIT 10.9

                                 LOAN AGREEMENT

       THIS LOAN AGREEMENT (the "Agreement") is made as of April 24, 2001 by and
between Northwest Biotherapeutics, Inc., a Delaware corporation (the "Company"),
and Holmes Harbor Company, Inc., a Washington corporation (the "Investor").

       A. Investor loaned the Company $1,650,000 pursuant to that certain
promissory note dated July 11, 2000 ("Original Loan").

       B. Company and Investor desire to restructure the Original Loan upon the
terms and subject to the conditions set forth in this Agreement.

       1. The Restructure; Closing.

              1.1 The Restructure. On the Closing Date (as defined in Section
1.2 below) the Company agrees to fully repay the Original Loan by (i) making a
payment to Investor of cash in the amount of $825,000, plus all accrued and
unpaid interest on the Original Loan on or before May 15, 2001 ("Repayment
Date"); (ii) issuing to Investor, a convertible promissory note evidencing the
Company's remaining debt obligation in the amount of $825,000 substantially in
the form attached hereto as Exhibit A, (the "Note") on the Repayment Date; (iii)
delivering to Investor an executed security agreement in substantially the form
attached hereto as Exhibit B (the "Security Agreement"); and (iv) issuing to
Investor a warrant to purchase up to 50,000 shares of the Company's Series D
Preferred Stock in substantially the form attached hereto as Exhibit C (the
"Warrant").

              1.2 Place and Date of Closing. The closing of the transactions
provided for herein (the "Closing") will be held at the offices of Lane Powell
Spears Lubersky LLP, 1420 Fifth Avenue, Suite 4100, Seattle, Washington 98101 at
2:00 p.m. on April 24, 2001 or at such other time and place as the parties shall
mutually agree (the "Closing Date").

              1.3 Delivery. At the Closing, (a) the Company will deliver to Lane
Powell Spears Lubersky LPP ("Escrow Agent"), to hold as escrow agent the Note,
the Security Agreement and the Warrant, which Escrow Agent will deliver to
Investor on the Repayment Date, and (b) Investor will deliver to Escrow Agent,
for cancellation, the promissory note and security agreement related to the
Original Loan, which Escrow Agent will hold until Investor has received the
payment referred to in subsection 1.1(i) above at which time such promissory
note and security agreement shall terminate and be of no further force and
effect.

       2. Representations and Warranties of the Company. The Company hereby
represents and warrants to Investor as follows:

              2.1 Organization and Standing. The Company is a corporation duly
organized and validly existing under, and by virtue of, the laws of the State of
Delaware and is in good standing under such laws. The Company has the requisite
corporate power to own and operate

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its properties and assets, and to carry on its business as presently conducted
and as proposed to be conducted.

              2.2 Corporate Power. The Company will have at the Closing, all
requisite legal and corporate power to execute and deliver this Agreement, to
carry out and perform its obligations under the terms of this Agreement.

              2.3 Authorization. The execution, delivery and performance of this
Agreement by the Company has been duly authorized by all requisite corporate
action, and constitutes the valid and binding obligations of the Company
enforceable in accordance with their respective terms, subject as to enforcement
of remedies to applicable bankruptcy, insolvency, reorganization or similar laws
relating to or affecting the enforcement of creditors' rights.

       3. Representations and Warranties of the Investor and Restrictions on
Transfer Imposed by the Securities Act of 1933.

              3.1 Representations and Warranties of Investor. Investor
represents and warrants to the Company as of the Closing Date:

                     (a) All action on the part of Investor for the
authorization, execution, delivery and performance by Investor of this Agreement
has been taken, and this Agreement constitutes a valid and binding obligation of
Investor, enforceable in accordance with its terms, except as may be limited by
applicable bankruptcy, insolvency, reorganization, or similar laws relating to
or affecting the enforcement of creditors' rights.

                     (b) Investor is acquiring the Note, Warrant and any shares
of Maker's stock issued pursuant to the conversion of the Note or exercise of
the Warrant (collectively the "Securities") for investment for its own account
and not with a view to, or for resale in connection with, any distribution.
Investor understands that the Securities to be acquired have not been registered
under the Act by reason of a specific exemption from the registration provisions
of the Act which depends upon, among other things, the bona fide nature of the
investment intent as expressed herein.

                     (c) Investor acknowledges that the Securities must be held
indefinitely unless subsequently registered under the Act or unless an exemption
from such registration is available. Investor is aware of the provisions of Rule
144 promulgated under the Act, which permits limited resale of securities
purchased in a private placement subject to the satisfaction of certain
conditions, including, in case the Investor has held the securities for less
than two years or is an affiliate of the Company, among other things: the
availability of certain current public information about the Company, the resale
occurring not less than one year after a party has purchased and paid for the
securities to be sold, the sale being through a "broker's transaction" or in
transactions directly with a "market maker," and the number of shares being sold
during any three-month period not exceeding specified limitations.

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              3.2 Legends. Each certificate representing any (equity) Securities
shall be endorsed with a legend in substantially the following form (in addition
to any legend required under applicable state securities laws):

              THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED
              FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
              ACT OF 1933. SUCH SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE
              ABSENCE OF SUCH REGISTRATION UNLESS SUCH SALE OR TRANSFER IS
              EXEMPT FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENT
              OF SAID ACT.

The Company need not record a transfer of Securities, unless the conditions
specified in the foregoing legend are satisfied. The Company may also instruct
its transfer agent not to record the transfer of any of the Securities unless
the conditions specified in the foregoing legends are satisfied.

       4. Defaults and Remedies.

              4.1 Events of Default. The following events shall be considered
Events of Default with respect to the Note:

                     (a) The Company shall default in the payment of any part of
the principal or accrued interest on any Note for more than thirty (30) days
after the same shall become due and payable, whether at maturity or at a date
fixed for prepayment or by acceleration or otherwise;

                     (b) The Company shall make an assignment for the benefit of
creditors, or shall admit in writing its inability to pay its debts as they
become due, or shall file a voluntary petition for bankruptcy, or shall file any
petition or answer seeking for itself any reorganization, arrangement,
composition, readjustment, dissolution or similar relief under any present or
future statute, law or regulation, or shall file any answer admitting the
material allegations of a petition filed against the Company in any such
proceeding, or shall seek or consent to or acquiesce in the appointment of any
trustee, receiver or liquidator of the Company, or of all or any substantial
part of the properties of the Company, or the Company or its respective
directors or majority stockholders shall take any action looking to the
dissolution or liquidation of the Company; or

                     (c) Within thirty (30) days after the commencement of any
proceeding against the Company seeking any reorganization, arrangement,
composition, readjustment, liquidation, dissolution or similar relief under any
present or future statute, law or regulation, such proceeding shall not have
been dismissed or, within thirty (30) days after the appointment without the
consent or acquiescence of the Company of any trustee, receiver or liquidator of
the Company or of all or any substantial part of the properties of the Company,
such appointment shall not have been vacated.

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              4.2 Remedies. Upon the occurrence of an Event of Default under
Section 4.1 hereof, at the option and upon the declaration of the holder of the
Note, (i) the entire unpaid principal and accrued interest on the Note held by
such holder shall, without presentment, demand, protest, or notice of any kind,
all of which are hereby expressly waived, be forthwith due and payable, and such
holder may, immediately and without expiration of any period of grace, enforce
payment of all amounts due and owing under such Note and exercise any and all
other remedies granted to it at law, in equity, or otherwise.

       5. Miscellaneous. Neither this Agreement nor any provisions hereof may be
changed, waived, discharged or terminated orally, but only by a signed statement
in writing.

              5.1 Governing Law. This Agreement shall be governed in all
respects by the laws of the State of Washington as such laws are applied to
agreements between Washington residents entered into and to be performed
entirely within Washington.

              5.2 Survival. The representations, warranties, covenants and
agreements made herein shall survive for a period of three years following the
Closing Date.

              5.3 Successors and Assigns. Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors and administrators of the
parties hereto.

              5.4 Entire Agreement. This Agreement and the other documents
delivered pursuant hereto constitute the full and entire understanding and
agreement between the parties with regard to the subjects hereof and thereof.

              5.5 Severability of this Agreement. In case any provision of this
Agreement shall be deemed to be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

              5.6 Titles and Subtitles. The titles of the Sections and
Subsections of this Agreement are for convenience of reference only and are not
to be considered in construing this Agreement.

              5.7 Delays or Omissions. It is agreed that no delay or omission to
exercise any right, power or remedy accruing to the Investor, upon any breach or
default of the Company under this Agreement or the Notes, shall impair any such
right, power or remedy, nor shall it be construed to be a waiver of any such
breach or default, or any acquiescence therein, or of any similar breach or
default thereafter occurring; nor shall any waiver of any single breach or
default be deemed a waiver of any other breach or default theretofore or
thereafter occurring. It is further agreed that any waiver, permit, consent or
approval of any kind or character by the Investor of any breach or default under
this Agreement, or any waiver by the Investor of any provisions or conditions of
this Agreement must be in writing and shall be effective only to the

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extent specifically set forth in writing and that all remedies, either under
this Agreement, or by law or otherwise afforded to the Investor, shall be
cumulative and not alternative.

              5.8 Notices. All notices and other communications required or
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, or otherwise delivered by facsimile
transmission, overnight express delivery with a reputable express delivery
service, by hand or by messenger, addressed:

       (a) if to Investor, to:

             Holmes Harbor Company, Inc.
             4640 - 95th Avenue SE
             Bellevue, Washington  98004-1301
             Attn:  President
             Fax: (425) 450-0793

or at such other address as Investor shall have furnished to the Company, with a
copy to:

       (b) if to the Company, to:

             Northwest Biotherapeutics, Inc.
             21720 - 23rd Drive SE, Suite 100
             Bothell, WA  98021
             Attn:  President
             Fax: (425) 608-3146

Each such notice or other communication shall for all purposes of this Agreement
be treated as effective or having been given: when received, if delivered
personally; if sent by facsimile, the first business day after the date of
confirmation that the facsimile has been successfully transmitted to the
facsimile number for the party notified; if sent by express mail, the first
business day following delivery with such service; or, if sent by mail, at the
earlier of its receipt or 72 hours after the same has been deposited in a
regularly maintained receptacle for the deposit of the United States mail,
addressed and mailed as aforesaid.

              5.9 Counterparts. This Agreement may be executed by facsimile and
in any number of counterparts, each of which shall be deemed an original, and
all of which together shall constitute one instrument.

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       IN WITNESS WHEREOF, the parties have caused this Loan Agreement to be
duly executed and delivered as of the day and year first written above.

THE "COMPANY":                          NORTHWEST BIOTHERAPEUTICS, INC.

                                        By:
                                           -------------------------------------
                                           Daniel O. Wilds, President

THE "INVESTOR":                         HOLMES HARBOR COMPANY, INC.

                                        By:
                                           -------------------------------------
                                           Robert M. Trimble, President

                        SIGNATURE PAGE TO LOAN AGREEMENT

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                                    EXHIBIT A

                           CONVERTIBLE PROMISSORY NOTE

$825,000.00                                                  Bothell, Washington
                                                                 April ___, 2001

       FOR VALUE RECEIVED, NORTHWEST BIOTHERAPEUTICS, INC., a Delaware
corporation ("Maker"), promises to pay HOLMES HARBOR COMPANY, INC., a Washington
corporation ("HHC"), the principal sum of Eight Hundred Twenty-Five Thousand and
00/100ths Dollars ($825,000.00), with interest on the unpaid principal balance
from the date of this Note, until paid, at the rate of thirteen percent (13%)
per annum. Principal and interest shall be payable at such place as HHC may
designate from time to time in writing, in quarterly installments of $121,603.36
each, beginning on September 30, 2001, and payment in full shall be on June 30,
2003 ("Maturity Date"). Maker may prepay any portion of this Note at any time
without any penalty.

       In the event of any failure to pay any payment required hereunder when
due, or any default hereunder, the entire balance, principal and interest, shall
bear interest at the annual rate of eighteen percent (18%), and shall at once
become due and payable at the option of HHC. HHC may exercise this option to
accelerate during any default by Maker regardless of any prior forbearance. If
suit is brought to collect this Note, HHC shall be entitled to collect all
reasonable costs and expenses of suit, including, but not limited to, reasonable
attorneys' fees. Maker may prepay the principal amount outstanding in whole or
in part at any time without penalty.

       Notwithstanding any other provision of this Note to the contrary, all
obligations hereunder shall be accelerated and this Note shall be payable in
full in any of the following events:

       1. On the sale of all or substantially all of Maker's assets;

       2. On the sale of Maker's issued and outstanding securities which
represent more than fifty percent (50%) of the voting rights of all of Maker's
securities; or

       3. The initial public offering of Maker's shares of common stock pursuant
to a registration statement filed with the Securities and Exchange Commission.

At HHC's election, the then principal amount of and accrued interest on this
Note shall be converted into shares of the Company's Series D Preferred Stock.
The number of shares of stock to be issued upon such conversion shall be equal
to the quotient obtained by dividing (i) the then outstanding principal amount
of this Note plus accrued interest by (ii) $5.00, rounded to the nearest whole
share.

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No fractional shares of the Company's stock will be issued upon conversion of
this Note. In lieu of any fractional share to which HHC would otherwise be
entitled, the Maker will pay to HHC cash in the amount of the unconverted
principal and accrued interest of this Note that would otherwise be converted
into such fractional share. Upon conversion of this Note, HHC shall surrender
this Note, duly endorsed, at the principal offices of the Maker or any transfer
agent of the Maker. At its expense, the Maker will, as soon as practicable
thereafter, issue and deliver to HHC a certificate or certificates for the
number of shares to which HHC is entitled upon such conversion, together with
any other securities and property to which HHC is entitled upon such conversion
under the terms of this Note, including a check payable to HHC for any cash
amounts payable as described herein. Upon conversion of this Note, the Maker
will be forever released from all of its obligations and liabilities under this
Note with regard to that portion of the principal amount and accrued interest
being converted including without limitation the obligation to pay such portion
of the principal amount and accrued interest.

       Presentment, notice of dishonor, and protest are hereby waived.

       Any notice of Maker provided for in this Note shall be given by mailing
such notice by certified mail addressed to Maker at such address as Maker may
designate by notice to HHC. Any notice to HHC shall be given by mailing such
notice by certified mail, return receipt requested, to HHC at such address as
may have been designated by notice to Maker.

       The indebtedness evidenced by this Note is secured by a Security
Agreement of even date.

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                                        NORTHWEST BIOTHERAPEUTICS, INC.

                                        By
                                          --------------------------------------
                                          Daniel O. Wilds, President and CEO

                        SIGNATURE PAGE OF PROMISSORY NOTE

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                                    EXHIBIT B

                               SECURITY AGREEMENT

       This Security Agreement is entered into effective April 24, 2001, between
Northwest Biotherapeutics, Inc., a Delaware corporation ("Debtor") and Holmes
Harbor Company, Inc., a Washington corporation ("Secured Party").

       1. GRANT OF SECURITY INTEREST. Debtor hereby grants, assigns, transfers,
pledges and conveys to Secured Party and its successors and assigns, a first
priority security interest in all of Debtor's rights, title and interest in, to
and under all of Debtor's assets wherever located, including without limitation:
(a) all existing and future accounts, contracts and contract rights, including
all accounts receivable, bank accounts, partnership and joint venture interests
and rights to distributions in connection therewith, rights under all invoices
and purchase orders and other documents representing payments for goods sold and
services rendered, and moneys due or to become due or payable or to become
payable in connection with any such accounts, contracts, or contract rights; (b)
all general intangibles, all other trade names, customer lists, trademarks and
trademark applications, business names, fictitious business names, service
marks, logos, labels, other source of business identifiers, prints and labels on
which any of the foregoing have appeared, designs and general intangibles of
like nature, patents and patent applications, including: (i) USPO No. 5,788,963
issued 08/04/98 (Isolation &/or Preservation of Dendritic Cells for Prostate
Cancer Immunotherapy), (ii) USPO No. 5,990,294, issued 11/23/99 (Nucleotide &
Amino Acid Sequences of C4-2, a Tumor Suppressor Gene & Methods of Use Thereof),
(iii) USPO No. 5,874,290 issued 02/23/99 (Nucleotide & Amino Acid Sequences of a
D2-2 Gene Associated with Brain Tumors and Methods based thereon), (iv) USPO No.
60/190,361, filed 4/07/00 (Human PCA-1 Antigen and Nucleic Acids: Diagnostic and
Therapeutic Uses), and (v) USPO No. [pending] filed 5/12/00 (Bacillus Calmette
Guerin (BCG) for Loading Dendritic Cells for Soluble Antigen Presentation),
copyrights and intellectual property rights, tax refund and claims, all rights
in litigation for any cause or claim now pending or hereafter arising, all
claims of Debtor against Secured Party, all rights to purchase real property,
all rights as a licensor, licensee or distributor of any kind, all royalties,
licenses and proprietary information, all data, licenses, computer programs,
software and hardware; (c) all insurance policies and claims, and all other
rights, privileges and franchises of every kind; (d) all supplies, fixed assets,
merchandise, products, equipment and inventory; and (e) all other personal
property of Debtor, tangible or intangible, whether now or hereafter owned by
Debtor; together with all increases, substitutions, additions and accretions in
said property and all the property of a similar nature hereafter acquired by
Debtor in any of the categories herein described; and together with all cash and
non-cash proceeds thereof (collectively, the "Collateral"); provided, however,
the Collateral shall not include the following pending or issued patents or
patent applications: (a) U.S. Patent Application Serial No. 09/044,668, allowed
2/23/00 (Monoclonal Antibodies Specific for the Extracellular Domain of
Prostate-Specific Membrane Antigen), now

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issued as U.S. Patent No. 6,150,508, as well as all foreign counterparts thereof
and all continuations in whole or in part, divisionals, renewals, substitutions,
conversions, reissues, reexaminations, prolongations or extensions thereof; (b)
PCT Application No. PCT/US99/07431, filed 3/29/99 (Therapeutic & Diagnostic
Applications Based on CXCR4 Gene in Tumorigenesis), as well as all national
phase counterparts thereof, and all corresponding U.S. applications and patents,
including all continuations in whole or in part, divisionals, renewals,
substitutions, conversions, reissues, reexaminations, prolongations or
extensions thereof; and (c) PCT Application No. PCT/US99/08079, filed 4/13/99
(Methods for the Diagnosis and Treatment of Metastic Prostate Tumors), as well
as all national phase counterparts thereof, and all corresponding U.S.
applications and patents, including all continuations in whole or in part,
divisionals, renewals, substitutions, conversions, reissues, reexaminations,
prolongations or extensions thereof.

       Debtor will cooperate with Secured Party with respect to the preparation
and filing of all applicable instruments and documents, including necessary
UCC-1 Financing Statements, and will sign same and all amendments thereto, and
continuation statements.

       2. OBLIGATION. This Security Agreement is given to secure the performance
of the obligations of Debtor and Secured Party ("Obligations") under that
certain Promissory Note and the documents and instruments executed in connection
therewith, dated as of the same date hereof (collectively, the "Note"), the
terms of which are incorporated herein by this reference.

       3. OWNERSHIP AND LIENS. Debtor owns the Collateral and the same is free
and clear of all security interests and encumbrances of every nature whatsoever.
Debtor shall not create nor permit the existence of any lien or security
interest on the Collateral, or sell, transfer, pledge, assign or otherwise
convey the Collateral, or any rights or interest therein, without the prior
written consent of Secured Party, which written consent Secured Party may grant
or not grant in its sole and subjective discretion.

       4. TAXES. Debtor shall pay before delinquency all taxes or other
governmental charges that are or may become a lien or charge on the Collateral.

       5. INSURANCE. Debtor shall keep the Collateral continuously insured
against fire, theft and other hazards, in an amount equal to the full insurable
value thereof or to all sums secured hereby, with a loss-payable clause in favor
of Secured Party. In the event of loss, Secured Party shall have full power to
collect any and all insurance upon the Collateral and to apply the same at its
option to any obligation secured hereby, whether or not matured. Secured Party
shall have no liability whatsoever for any loss that may occur by reason of the
omission or lack of coverage of any such insurance.

       6. DEFAULT. Any of the following is an event of default under this
Agreement and Note:

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              (a) Any failure by Debtor to timely perform as required herein or
under the Note;

              (b) Falsity of any warranty or representation by Debtor herein or
in any financial or other statements, writings, reports or communications made
or delivered to Secured Party in connection with the transactions contemplated
in or by the Note;

              (c) Commencement of voluntary or involuntary bankruptcy,
receivership or insolvency proceedings by or against, or the insolvency or
business failure of, Debtor;

              (d) Failure by Debtor to pay its debts as they become due;

              (e) Levy on, seizure, or attachment of any of the Collateral, or
judgment against Debtor in an amount exceeding $100,000; or

              (f) The sale, assignment, transfer, pledge or conveyance of any
kind whatsoever of any of the Collateral without Secured Party's prior written
consent.

       7. REMEDIES: In the event of a default under this Security Agreement, all
sums and indemnity obligations (whether contingent or uncontingent, liquidated
or unliquidated) due or to become due under or by reason of the Note shall
become immediately due and payable at Secured Party's option without notice to
Debtor, and Secured Party may proceed to enforce payment of same and exercise
any and all rights and remedies granted to it herein and in the Note, and in any
other instrument or agreement securing, evidencing or relating thereto, and all
rights and remedies available under any applicable law, including the Washington
Uniform Commercial Code, RCW 62A in force as of the date hereof. Without
limiting the generality of the foregoing, Secured Party shall have any or all of
the following rights and remedies:

              (a) At Secured Party's request, Debtor shall assemble the
Collateral and make it available to Secured Party at a place Secured Party
designates which is reasonably convenient to both parties;

              (b) Debtor agrees to put Secured Party into immediate possession
of the Collateral upon demand;

              (c) All payments received by Debtor under or in connection with
any of the Collateral shall, at Secured Party's election, be deposited in a
segregated FDIC-insured bank account in trust for the sole benefit of Secured
Party, or immediately upon receipt by Debtor or Secured Party, turned over to
Secured Party, in the same form as received (duly endorsed in favor of Secured
Party if and as required in its discretion);

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              (d) Secured Party is authorized, without notice, demand or legal
proceedings, to enter any premises where the Collateral is situated and take
possession of, keep, store or remove any of the Collateral, and remain, or cause
a custodian of its choice to remain, on the premises in exclusive control
thereof without charge so long as Secured Party deems it reasonably necessary to
complete the enforcement of its rights hereunder or under the Note; provided
that should Secured Party seek to take possession of any of the Collateral by
court process, Debtor hereby irrevocably waives (i) any bond, surety or security
relating thereto required by any statute, court rule or otherwise as an incident
to such possession, (ii) any demand for possession prior to commencement of such
court process, and (iii) any requirement that Secured Party retain possession of
and not dispose of any such Collateral until after trial or final judgment;

              (e) Demand payment of, and collect, any accounts and general
intangibles comprising Collateral and, in connection therewith, Debtor
irrevocably authorizes Secured Party to endorse or sign Debtor's name, as
pertinent, on all collections, receipts, instruments and other documents as
required in its discretion, to take possession of and open mail addressed to
Debtor and remove therefrom payments made with respect to any item of the
Collateral or proceeds thereof, and, in Secured Party's sole discretion, to
grant extensions of time to pay, compromise claims and settle accounts and the
like for less than face value;

              (f) Demand and receive possession of any of Debtor's federal and
state taxes and the books and records utilized in the preparation thereof or
referring thereto; and

              (g) Debtor shall pay on demand all expenses actually incurred by
Secured Party in protecting, realizing upon, repossessing, and selling the
Collateral, or in interpreting or enforcing its rights hereunder, including
Secured Party's court costs and actual attorneys' fees incurred in both trial
and appellate courts (including all fees and costs incurred in any bankruptcy
court hearings of any kind whatsoever, including relief from stay proceedings,
disclosure statement and plan confirmation proceedings, nondischargeability
proceedings, claim objection proceedings, adversary proceedings, and
investigating, preparing and filing proofs of claims), or fees or costs incurred
without suit. The covenant to pay the sums as provided in this subparagraph 7(g)
shall be secured by this Security Agreement.

       8. APPOINTMENT AS ATTORNEY-IN-FACT. Debtor hereby irrevocably constitutes
and appoints Secured Party, and any officer or agent thereof, with full power
and substitution, as its true and lawful Attorney-in-Fact with full irrevocable
power and authority in their place and stead or in Secured Party's own name,
from time to time in Secured Party's discretion, for the purpose of carrying out
the terms of this Security Agreement and the Note and other instruments executed
in connection herewith, to take any and all appropriate actions and to execute
all documents and instruments which may be necessary or desirable in Secured
Party's opinion to accomplish the purposes of such documents and, without
limiting the generality of the foregoing, hereby give Secured Party the power
and right, on behalf of Debtor, without notice to or assent by it, upon a
default hereunder or under the Note, to: (i) ask, demand, collect, receive and
give

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acquittances and receipt for any and all monies due and to become due under any
Collateral, (ii) in the name of Debtor or in its own name, or otherwise, take
possession of and endorse and collect any checks, drafts, notes, acceptances or
other instruments for the payment of monies due under or by reason of any
Collateral, (iii) grant extensions of time to pay, compromise and settle claims,
accounts and general intangibles for less than face value and execute all
releases and other documents in connection therewith, (iv) file any claim or
commence and prosecute any action or proceeding in any court of law or equity or
take any other action deemed appropriate by Secured Party for the purpose of
collecting any and all such monies due in respect of any Collateral whenever
payable and to enforce any other right in respect thereof; (v) direct any party
liable for any payment in respect of any of the Collateral to make such payment
directly to Secured Party or as it shall direct; (vi) sign and endorse any
invoices, freight or express bills, bills of lading, storage or warehouse
receipts, assignments and notices in connection with accounts and other
documents relating to the Collateral; (vii) defend any suit, action or
proceeding brought against Debtor with respect to any Collateral; (viii)
generally to sell, transfer pledge, or otherwise deal with any of the Collateral
as fully as though Secured Party were the absolute owner thereof for all
purposes, and to do, at Secured Party's option and Debtor's expense, from time
to time all acts and things which Secured Party deems necessary to protect,
preserve or realize upon the Collateral and Secured Party's rights and interests
to, in and under the Collateral.

       This power of attorney is a power coupled with an interest and shall be
irrevocable. The powers conferred upon Secured Party hereunder are solely to
protect its rights and interests in, to and under the Collateral and shall not
impose any duty upon it to exercise any such powers. Secured Party shall be
accountable only for amounts that are actually received as a result of the
exercise of such powers, and neither it nor any of its officers, directors,
shareholders, employees, or agents shall be responsible to Debtor for any act or
omission whatsoever.

       Debtor hereby authorizes Secured Party, from time to time, (i) to
communicate directly in its own name with any party who is obligated to Debtor
with regard to the assignment and collection of such obligation and other
matters relating thereto, and (ii) to execute any endorsements, assignments or
other instruments of conveyance or transfer with respect to the Collateral in
connection with any sale or other conveyance or transfer thereof pursuant to
section 7 above.

       9. TAX INDEMNIFICATION. Debtor agrees to pay, and to defend, save and
hold Secured Party harmless from and against any and all liabilities with
respect to, or resulting from any delay in paying any excise, sales or other
taxes which may be payable or determined to be payable with respect to any of
the Collateral or in connection with any of the transactions contemplated by
this Security Agreement.

                                      B-5
<PAGE>   15

       10. NOTICE. Any notice given pursuant to this Security Agreement shall be
effective when mailed, postage prepaid, by certified or registered mail (return
receipt requested), or by personal service, at the following addresses:

       Notice to Debtor:            Northwest Biotherapeutics, Inc.
                                    2203 Airport Way South, Suite 200
                                    Seattle, WA  98134
                                    Attn:  Daniel O. Wilds, President

       Notice to Secured Party:     Holmes Harbor Company, Inc.
                                    4640 95th Avenue NE
                                    Bellevue, WA  98004-1301
                                    Attn:  Bob Trimble, President

       11. MISCELLANEOUS.

              (a) Waiver. This Security Agreement shall not be qualified or
supplemented by course of dealing. No waiver or modification by Secured Party of
any of the terms or conditions hereof shall be effective unless in writing
signed by Secured Party. No waiver nor indulgence by Secured Party as to any
required performance by Debtor shall constitute a waiver as to any subsequent
required performance or other obligations of Debtor hereunder.

              (b) Benefit. This Agreement shall be binding upon, and inure to
the benefit of, the respective legal representatives, successors and assigns of
the parties hereto.

              (c) Construction. This Agreement is being executed and delivered
and is intended to be performed in the State of Washington, and shall be
construed and enforced in accordance with the laws of that state.

              (d) Venue. The parties agree the venue of any suit or action
between the parties-will be in the Superior Court for King County, Seattle,
Washington.

              (e) Severability. Should any provision of this Agreement be held
by any court of competent jurisdiction to be void or unenforceable, such defect
shall not affect the remainder of this Agreement, which shall continue in full
force and effect.

              (f) Counterparts, Facsimile Copies. This Agreement may be executed
in one or more counterparts, each of which shall be deemed an original, but all
of which together shall constitute one and the same instrument. Facsimile copies
hereof may be executed as counterpart originals.

                                      B-6
<PAGE>   16

              (g) Termination of Security Interest. When all sums owed Secured
Party have been paid and all Obligations of Debtor fulfilled under this
Agreement and the Note, Secured Party will prepare, sign and file appropriate
UCC-3 Termination Statements.

                  [Remainder of page left intentionally blank]

                                      B-7
<PAGE>   17

       SIGNED effective as of the date first above written.

DEBTOR:                                 SECURED PARTY:

NORTHWEST BIOTHERAPEUTICS, INC.         HOLMES HARBOR COMPANY, INC.

By                                      By
  ---------------------------------       --------------------------------------
  Daniel O. Wilds, President & CEO        Bob Trimble, President

                      SIGNATURE PAGE OF SECURITY AGREEMENT

                                      B-8
<PAGE>   18

                                    EXHIBIT C

       THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AND HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT
WITH A VIEW TO, OR IN CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF. NO SUCH
SALE OR DISTRIBUTION MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT
RELATED THERETO OR AN OPINION OF COUNSEL IN A FORM SATISFACTORY TO THE COMPANY
THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES ACT OF 1933.

PDW-13                                         Date of Issuance:  April 24, 2001
                                                Expiration Date:  April 23, 2011

                         NORTHWEST BIOTHERAPEUTICS, INC.

                                     WARRANT

       Northwest Biotherapeutics, Inc. (the "Company"), for value received,
hereby certifies that HOLMES HARBOR COMPANY, INC. or its registered assigns (the
"Registered Holder"), is entitled, subject to the terms set forth below, to
purchase from the Company, at any time after the date hereof and on or before
the Expiration Date (as defined in Section 5 below), up to 50,000 shares of
Series D Preferred Stock of the Company ("Equity Securities"), at a purchase
price of $5.00 per share. The Equity Securities purchasable upon exercise of
this Warrant, and the purchase price per share, as adjusted from time to time
pursuant to the provisions of this Warrant, are hereinafter referred to as the
"Warrant Stock" and the "Purchase Price," respectively.

       1. Exercise.

              (a) Manner of Exercise. This Warrant may be exercised by the
Registered Holder for the portion of shares of Warrant Stock that have vested
pursuant to the following schedule, by surrendering this Warrant, with the
purchase/exercise form appended hereto as Attachment A duty executed by the
Registered Holder at the principal office of the Company, or at such other
office or agency as the Company may designate, accompanied by payment in full of
the Purchase Price payable in respect of the number of shares of Warrant Stock
purchased upon such exercise. The vesting schedule shall be as follows:

       -      10,000 shares of Warrant Stock if the loan evidenced by that
              certain promissory note in the amount of $825,000 of even date
              herewith (the "Loan") is fully paid by the Company on or before
              June 30, 2001;

       -      33,000 shares of Warrant Stock if the Loan is fully paid by the
              Company on or before June 30, 2002; and

                                      C-1
<PAGE>   19

       -      50,000 shares of Warrant Stock if the Loan is fully paid by the
              Company after June 30, 2002.

The Purchase Price may be paid by cash, check, wire transfer, or by the
surrender of promissory notes or other instruments representing indebtedness of
the Company to the Registered Holder.

              (b) Effective Time of Exercise. Each exercise of this Warrant
shall be deemed to have been effected immediately prior to the close of business
on the day on which this Warrant shall have been surrendered to the Company as
provided in Section 1(a) above. At such time, the person or persons in whose
name or names any certificates for Warrant Stock shall be issuable upon such
exercise as provided in Section 1(d) below shall be deemed to have become the
holder or holders of record of the Warrant Stock represented by such
certificates.

              (c) Net Issue Exercise.

                     (i) In lieu of exercising this Warrant in the manner
       provided above in Section 1(a), the Registered Holder may elect to
       receive shares of Warrant Stock equal to the value of this Warrant (or
       the portion thereof being canceled) by surrender of this Warrant at the
       principal office of the Company together with notice of such election on
       the purchase/exercise form appended hereto as Attachment A duly executed
       by such Registered Holder or such Registered Holder's duly authorized
       attorney, in which event the Company shall issue to such Registered
       Holder a number of shares of Warrant Stock computed using the following
       formula:

                                  X = Y (A - B)
                                      ---------
                                          A

       Where   X =  The number of shares of Warrant Stock to be issued to the
                    Registered Holder.

               Y =  The number of shares of Warrant Stock purchasable under this
                    Warrant (at the date of such calculation).

               A =  The fair market value of one share of Warrant Stock (at the
                    date of such calculation).

               B =  The Purchase Price (as adjusted to the date of such
                    calculation).

                     (ii) For purposes of this Section 1(c), the fair market
       value of Warrant Stock on the date of calculation shall mean with respect
       to each share of Warrant Stock:

                                      C-2
<PAGE>   20

                            (A) if the exercise is in connection with the
              Company's IPO, and if the Company's Registration Statement
              relating to such IPO has been declared effective by the Securities
              and Exchange Commission, then the fair market value per share
              shall be the product of (x) the initial "Price to Public"
              specified in the final prospectus with respect to the IPO and (y)
              the number of shares of Common Stock into which each share of
              Warrant Stock is convertible at the date of calculation;

                            (B) if (A) is not applicable, the fair market value
              of Warrant Stock shall be at the highest price per share which the
              Company could obtain on the date of calculation from a willing
              buyer (not a current employee or director) for shares of Warrant
              Stock sold by the Company, from authorized but unissued shares, as
              determined in good faith by the Board of Directors, unless the
              Company is at such time subject to an acquisition as described in
              Section 5(b) below, in which case the fair market value of Warrant
              Stock shall be deemed to be the value received by the holders of
              such stock pursuant to such acquisition.

              (d) Delivery to Registered Holder. As soon as practicable after
the exercise of this Warrant in whole or in part, and in any event within ten
(10) days thereafter, the Company at its expense will cause to be issued in the
name of, and delivered to, the Registered Holder, or as such Registered Holder
(upon payment by such Registered Holder of any applicable transfer taxes) may
direct:

                     (i) a certificate or certificates for the number of shares
       of Warrant Stock to which such Registered Holder shall be entitled, and

                     (ii) in case such exercise is in part only, a new Warrant
       or Warrants (dated the date hereof) of like tenor, calling in the
       aggregate on the face or faces thereof for the number of shares of
       Warrant Stock equal (without giving effect to any adjustment therein) to
       the number of such shares called for on the face of this Warrant minus
       the number of such shares purchased by the Registered Holder upon such
       exercise as provided in Section 1(a) or 1(c) above.

       2. Adjustments.

              (a) Redemption or Conversion of Capital Stock. If the Company's
capital stock is redeemed or converted into other equity securities of the
Company ("Conversion Shares"), then this Warrant shall automatically become
exercisable for that number of Conversion Shares equal to the number of
Conversion Shares that would have been received if this Warrant had been
exercised in full and the shares of Equity Securities received thereupon had
been simultaneously converted into Conversion Shares immediately prior to such
event, and the Exercise Price shall be automatically adjusted to equal the
number obtained by dividing (i) the aggregate Purchase Price of the shares of
Warrant Stock for which this Warrant was

                                      C-3
<PAGE>   21

exercisable immediately prior to such redemption or conversion, by (ii) the
number of Conversion Shares for which this Warrant is exercisable immediately
after such redemption or conversion.

              (b) Stock Splits and Dividends. If outstanding shares of the
Company's capital stock shall be subdivided into a greater number of shares or a
dividend in capital stock shall be paid in respect of Warrant Stock, the
Purchase Price in effect immediately prior to such subdivision or at the record
date of such dividend shall simultaneously with the effectiveness of such
subdivision or immediately after the record date of such dividend be
proportionately reduced. If outstanding shares of capital stock shall be
combined into a smaller number of shares, the Purchase Price in effect
immediately prior to such combination shall, simultaneously with the
effectiveness of such combination, be proportionately increased. When any
adjustment is required to be made in the Purchase Price, the number of shares of
Warrant Stock purchasable upon the exercise of this Warrant shall be changed to
the number determined by dividing (i) an amount equal to the number of shares
issuable upon the exercise of this Warrant immediately prior to such adjustment,
multiplied by the Purchase Price in effect immediately prior to such adjustment,
by (ii) the Purchase Price in effect immediately after such adjustment.

              (c) Reclassification, Etc. In case there occurs any
reclassification or change of the outstanding securities of the Company or of
any reorganization of the Company (or any other corporation the stock or
securities of which are at the time receivable upon the exercise of this
Warrant) or any similar corporate reorganization on or after the date hereof,
then and in each such case the Registered Holder, upon the exercise hereof at
any time after the consummation of such reclassification, change, or
reorganization shall, be entitled to receive, in lieu of the stock or other
securities and property receivable upon the exercise hereof prior to such
consummation, the stock or other securities or property to which such Registered
Holder would have been entitled upon such consummation if such Registered Holder
had exercised this Warrant immediately prior thereto, all subject to further
adjustment pursuant to the provisions of this Section 2.

              (d) Adjustment Certificate. When any adjustment is required to be
made in the Warrant Stock or the Purchase Price pursuant to this Section 2, the
Company shall promptly mail to the Registered Holder a certificate setting forth
(i) a brief statement of the facts requiring such adjustment, (ii) the Purchase
Price after such adjustment, and (iii) the kind and amount of stock or other
securities or property into which this Warrant shall be exercisable after such
adjustment.

              (e) Acknowledgment. In order to avoid doubt, it is acknowledged
that the Registered Holder of this Warrant shall be entitled to the benefit of
all adjustments in the number of shares of Common Stock of the Company issuable
upon conversion of the Warrant Stock (if applicable) which occur prior to the
exercise of this Warrant, including without limitation, any increase in the
number of shares of Common Stock issuable upon conversion as a result of a
dilutive issuance of capital stock (if applicable).

                                      C-4
<PAGE>   22

       3. Transfers.

              (a) Unregistered Security. Each Registered Holder of this Warrant
acknowledges that this Warrant, the Warrant Stock and the Common Stock of the
Company have not been registered under the Securities Act of 1933, as amended
(the "Securities Act"), and agrees not to sell, pledge, distribute, offer for
sale, transfer or otherwise dispose of this Warrant, any Warrant Stock issued
upon its exercise or any Common Stock issued upon conversion of the Warrant
Stock in the absence of (i) an effective registration statement under the Act as
to this Warrant, such Warrant Stock or such Common Stock and registration or
qualification of this Warrant, such Warrant Stock or such Common Stock under any
applicable U.S. federal or state securities law then in effect, or (ii) an
opinion of counsel, satisfactory to the Company, that such registration and
qualification are not required. Each certificate or other instrument for Warrant
Stock issued upon the exercise of this Warrant shall bear a legend substantially
to the foregoing effect.

              (b) Transferability. Subject to the provisions of Section 3(a)
hereof, this Warrant and all rights hereunder are transferable, in whole or in
part, upon surrender of the Warrant with a properly executed assignment (in the
form of Attachment B hereto) at the principal office of the Company provided,
however, that this Warrant may not be transferred unless the transferee acquires
the right to purchase all shares of Warrant Stock hereunder.

              (c) Warrant Register. The Company will maintain a register
containing the names and addresses of the Registered Holder of this Warrant.
Until any transfer of this Warrant is made in the warrant register, the Company
may treat the Registered Holder of this Warrant as the absolute owner hereof for
all purposes; provided, however, that if this Warrant is properly assigned in
blank, the Company may (but shall not be required to) treat the bearer hereof as
the absolute owner hereof for all purposes, notwithstanding any notice to the
contrary. Any Registered Holder may change such Registered Holder's address as
shown on the warrant register by written notice to the Company requesting such
change.

              (d) Market Standoff Agreement. In connection with the Company's
IPO and upon request of the Company or the underwriters managing such offering
of the Company's securities, Registered Holder agrees not to sell, make any
short sale of, loan, grant any option for the purchase of, or otherwise dispose
of any securities of the Company (other than those included in the registration)
without the prior written consent of the Company or such underwriters, as the
case may be, for such period of time (not to exceed 180 days) from the effective
date of such registration as may be requested by the Company or such managing
underwriters and to execute an agreement reflecting the foregoing as may be
requested by the underwriters at the time of the Company's IPO.

       4. No Impairment. The Company will not, by amendment of its charter or
through reorganization, consolidation, merger, dissolution, sale of assets or
any other voluntary action, avoid or seek to avoid the observance or performance
of any of the terms of this Warrant, but

                                      C-5
<PAGE>   23

will (subject to Section 13 below) at all times in good faith assist in the
carrying out of all such terms and in the taking of all such action as may be
necessary or appropriate in order to protect the rights of the Registered Holder
of this Warrant against impairment.

       5. Termination. This Warrant (and the right to purchase securities upon
exercise hereof) shall terminate upon the earliest to occur of the following
(the "Expiration Date"): (a) April 23, 2011, (b) the sale, conveyance or
disposal of all or substantially all of the Company's property or business or
the Company's merger into or consolidation with any other corporation (other
than a wholly-owned subsidiary of the Company) or any other transaction or
series of related transactions in which more than fifty percent (50%) of the
voting power of the Company is disposed of, provided that this Section 5(b)
shall not apply to a merger effected exclusively for the purpose of changing the
domicile of the Company, or (c) the closing of a firm commitment underwritten
public offering pursuant to a registration statement.

       6. Notices of Certain Transactions. In case:

              (a) the Company shall take a record of the holders of its capital
stock for the purpose of entitling or enabling them to receive any dividend or
other distribution, or to receive any right to subscribe for or purchase any
shares of stock of any class or any other securities, or to receive any other
right, to subscribe for or purchase any shares of stock of any class or any
other securities, or to receive any other right, or

              (b) of any capital reorganization of the Company, any
reclassification of the capital stock of the Company, any consolidation or
merger of the Company, any consolidation or merger of the Company with or into
another corporation (other than a consolidation or merger in which the Company
is the surviving entity), or any transfer of all or substantially all of the
assets of the Company, or

              (c) of the voluntary or involuntary dissolution, liquidation or
winding-up of the Company, or

              (d) of any redemption of the Preferred Stock or mandatory
conversion of the Preferred Stock into Common Stock of the Company,

then, and in each such case, the Company will mail or cause to be mailed to the
Registered Holder of this Warrant a notice specifying, as the case may be, (i)
the date on which a record is to be taken for the purpose of such dividend,
distribution or right, and stating the amount and character of such dividend,
distribution or right, or (ii) the effective date on which such reorganization,
reclassification, consolidation, merger, transfer, dissolution, liquidation,
winding-up, redemption or conversion is to take place, and the time, if any is
to be fixed, as of which the holders of record of the Company's capital stock
are to be determined. Such notice shall be mailed at least ten (10) days prior
to the record date or effective date for the event specified in such notice.

                                      C-6
<PAGE>   24

       7. Reservation of Stock. The Company will at all times reserve and keep
available, solely for the issuance and delivery upon the exercise of this
Warrant, such shares of Warrant Stock and other stock, securities and property,
as from time to time shall be issuable upon the exercise of this Warrant.

       8. Exchange of Warrants. Upon the surrender by the Registered Holder of
any Warrant or Warrants, properly endorsed, to the Company at the principal
office of the Company, the Company will, subject to the provisions of Section 3
hereof, issue and deliver to or upon the order of such Registered Holder, at the
Company's expense, a new Warrant or Warrants of like tenor, in the name of such
Registered Holder or as such Registered Holder (upon payment by such Registered
Holder of any applicable transfer taxes) may direct, calling in the aggregate on
the face or faces thereof for the number of shares of Warrant Stock called for
on the face or faces of the Warrant or Warrants so surrendered.

       9. Replacement of Warrants. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and (in the case of loss, theft or destruction) upon delivery of an
indemnity agreement (with surety if reasonably required) in an amount reasonably
satisfactory to the Company, or (in the case of mutilation) upon surrender and
cancellation of this Warrant, the Company will issue, in lieu thereof, a new
Warrant of like tenor.

       10. Mailing of Notices. Any notice required or permitted pursuant to this
Warrant shall be in writing and shall be deemed sufficient upon receipt, when
delivered personally or sent 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, addressed (a) if to the Registered Holder, to the address of the
Registered Holder most recently furnished in writing to the Company and (b) if
to the Company, to the address set forth below or subsequently modified by
written notice to the Registered Holder.

       11. No Rights as Stockholder. Until the exercise of this Warrant, the
Registered Holder of this Warrant shall not have or exercise any rights by
virtue hereof as a stockholder of the Company.

       12. No Fractional Shares. No fractional shares of Warrant Stock will be
issued in connection with any exercise hereunder. In lieu of any fractional
shares which would otherwise be issuable, the Company shall pay cash equal to
the product of such fraction multiplied by the fair market value of one share of
Warrant Stock on the date of exercise, as determined in good faith by the
Company's Board of Directors.

       13. Amendment or Waiver. Any term of this Warrant may be amended or
waived upon written consent of the Company and the holders of at least 50% of
the Warrant Stock issuable upon exercise of outstanding warrants purchased
pursuant to the Purchase Agreement.

                                      C-7
<PAGE>   25

By acceptance hereof, the Registered Holder acknowledges that in the event the
required consent is obtained, any term of this Warrant may be amended or waived
with or without the consent of the Registered Holder; provided, however, that
any amendment hereof that would materially adversely affect the Registered
Holder in a manner different from the holders of the remaining Warrants issued
pursuant to the Purchase Agreement shall also require the consent of Registered
Holder.

       14. Headings. The headings in this Warrant are for purposes of reference
only and shall not limit or otherwise affect the meaning of any provision of
this Warrant.

       15. Governing Law. This Warrant 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.

                                        NORTHWEST BIOTHERAPEUTICS, INC.

                                        By:
                                           -------------------------------------
                                           Daniel O. Wilds, President & C.E.O.
                                           21720 -- 23rd Drive SE, Suite 100
                                           Bothell, Washington  98021
                                           Facsimile Number:  (425) 608-3026

                                      C-8
<PAGE>   26

                                  ATTACHMENT A

                             PURCHASE/EXERCISE FORM

To:    Northwest Biotherapeutics, Inc.

       The undersigned, pursuant to the provisions set forth in the attached
Warrant No. PDW-____ hereby irrevocably elects to (a) purchase _________ shares
of the Warrant Stock covered by such Warrant and herewith makes payment of
$__________, representing the full purchase price for such shares at the price
per share provided for in such Warrant, or (b) exercise such Warrant for
____________ shares purchasable under the Warrant pursuant to the Net Issue
Exercise provisions of Section 1(c) of such Warrant.

       The undersigned acknowledges that it has reviewed the representations and
warranties contained in Section 2 of the Purchase Agreement (as defined in the
Warrant) and by its signature below hereby makes such representations and
warranties to the Company. Defined terms contained in such representations and
warranties shall have the meanings assigned to them in the Purchase Agreement,
provided that the term "Purchaser" shall refer to the undersigned and the term
"Securities" shall refer to the Warrant Stock.

Dated:                                  HOLMES HARBOR COMPANY, INC.
      ------------------------------

                                        By:
                                           -------------------------------------
                                        Its:
                                            ------------------------------------

                                      C-9
<PAGE>   27

                                  ATTACHMENT B

                                 ASSIGNMENT FORM

       FOR VALUE RECEIVED, Holmes Harbor Company, Inc. hereby sells, assigns and
transfers all of the rights of the undersigned under the attached Warrant with
respect to the number of shares of 50,000 covered thereby set forth below, unto:

NAME OF ASSIGNEE            ADDRESS/FACSIMILE NUMBER               NO. OF SHARES

Dated:                                  HOLMES HARBOR COMPANY, INC.
      -------------------------------

                                        By:
                                           -------------------------------------
                                        Its:
                                            ------------------------------------

                                        Witness:
                                                --------------------------------

                                      C-10
<PAGE>   28
                             COLLATERAL DESCRIPTION

(a) All existing and future accounts, contracts and contract rights, including
all accounts receivable, bank accounts, partnership and joint venture interests
and rights to distributions in connection therewith, rights under all invoices
and purchase orders and other documents representing payments for goods sold and
services rendered, and moneys due or to become due or payable or to become
payable in connection with any such accounts, contracts or contract rights; (b)
all general intangibles, all other trade names, customer lists, trademarks and
trademark applications, business names, fictitious business names, service
marks, logos, labels, other source of business identifiers, prints and labels on
which any of the foregoing have appeared, designs and general intangibles of
like nature, patents and patent applications, copyrights, and intellectual
property rights, tax refunds and claims, all rights in litigation for any cause
or claim now pending or hereafter arising, all judgments now or hereafter
arising, all claims of Debtor against Secured Party, all rights to purchase real
property, all rights its a licensor, licensee or distributor of any kind, all
royalties, licenses and proprietary information, all data, licenses, computer
programs, software and hardware; (c) all insurance policies and claims, and all
other rights, privileges and franchises of every kind; (d) all supplies, fixed
assets, merchandise, products, equipment and inventory; (e) all other personal
property of Debtor, tangible or intangible, whether now or hereafter owned by
Debtor; together with all increases, substitutions, additions and accretions in
said property and all the property of a similar nature hereafter acquired by
Debtor in any of the categories herein described; and together with all cash and
non-cash proceeds thereof (collectively, the "Collateral").
<PAGE>   29
                               SECURITY AGREEMENT

        This Security Agreement is entered into effective July 1, 1997, between
Northwest Biotherapeutics LLC, a Washington limited liability company ("Debtor")
and Northwest Hospital, a Washington nonprofit corporation ("Secured Party").

        1. GRANT OF SECURITY INTEREST. Debtor hereby grants, assigns, transfers,
pledges and conveys to Secured Party and his successors and assigns, a first
priority security interest in all of Debtor's rights, title and interest in, to
and under all of Debtor's assets wherever located, including without limitation:
(a) al existing and future accounts, contracts and contract rights, including
all accounts receivable, bank accounts, partnership and joint venture interests
and rights to distributions in connection therewith, rights under all invoices
and purchase orders and other documents representing payments for goods sold and
services rendered, and moneys due or to become due or payable or to become
payable in connection with any such accounts, contracts or contract rights; (b)
all general intangibles, all other trade names, customer lists, trademarks and
trademark applications, business names, fictitious business names, service
marks, logos, labels, other source of business identifiers, prints and labels on
which any of the foregoing have appeared, designs and general intangibles of
like nature, patents and patent applications, copyrights, and intellectual
property rights, tax refunds and claims, all rights in litigation for any cause
or claim now pending or hereafter arising, all judgments now or hereafter
arising, all claims of Debtor against Secured Party, all rights to purchase real
property, all rights as a licensor, licensee or distributor of any kind, all
royalties, licenses and proprietary information, all data, licenses, computer
programs, software and hardware; (c) all insurance policies and claims, and all
other rights, privileges and franchises of every kind; (d) all supplies, fixed
assets, merchandise, products, equipment and inventory; (e) all other personal
property of Debtor, tangible or intangible, whether now or hereafter owned by
Debtor; together with all increases, substitutions, additions and accretions in
said property and all the property of a similar nature hereafter acquired by
Debtor in any of the categories herein described; and together with all cash and
non-cash proceeds thereof (collectively, the "Collateral").

        Debtor will cooperate with Secured Party with respect to the preparation
and filing of all applicable instruments and documents, including necessary
UCC-1 Financing Statements, and will sign same and all amendments thereto, and
continuation statements.

        2. OBLIGATION. This Security Agreement is given to secure the
performance of the obligations of Debtor and Secured Party ("Obligations") under
that certain Master Note for Line of Credit, and the documents and instruments
executed in connection therewith, dated as of the same date hereof
(collectively, the "Note"), the terms of which are incorporated herein by this
reference.

        3. OWNERSHIP AND LIENS. Debtor owns the Collateral and the same is free
and clear of all security interests and encumbrances of every nature whatsoever.
Debtor shall not create nor permit the existence of any lien or security
interest on the Collateral, or sell, transfer, pledge, assign or otherwise
convey the Collateral, or any rights or interest therein, without the prior
<PAGE>   30
written consent of Secured Party, which written consent Secured Party may grant
or not grant in its sole and subjective discretion.

        4. TAXES. Debtor shall pay before delinquency all taxes or other
governmental charges that are or may become a lien or charge on the Collateral.

        5. INSURANCE. Debtor shall keep the Collateral continuously insured
against fire, theft and other hazards, in an amount equal to the full insurable
value thereof or to all sums secured hereby, with a loss-payable clause in favor
of Secured Party. In the event of loss, Secured Party shall have full power to
collect any and all insurance upon the Collateral and to apply the same at its
option to any obligation secured hereby, whether or not matured. Secured Party
shall have no liability whatsoever for any loss that may occur by reason of the
omission or lack of coverage of any such insurance.

        6. DEFAULT. Any of the following is an event of default under this
Agreement and Note:

           (a) Any failure by Debtor to timely perform as required herein or
under the Note;

           (b) Falsity of any warranty or representation by Debtor herein or in
any financial or other statements, writings, reports or communications made or
delivered to Secured Party in connection with the transactions contemplated in
or by the Note;

           (c) Commencement of voluntary or involuntary bankruptcy, receivership
or insolvency proceedings by or against, or the insolvency or business failure
of, Debtor;

           (d) Failure by Debtor to pay its debts as they become due;

           (e) Levy on, seizure, or attachment of any of the Collateral, or
judgment against Debtor in an amount exceeding $100,000; or

           (f) The sale, assignment, transfer, pledge or conveyance of any kind
whatsoever of any of the Collateral without Secured Party's prior written
consent.

        7. REMEDIES. In the event of a default under this Security Agreement,
all sums and indemnity obligations (whether contingent or uncontingent,
liquidated or unliquidated) due or to become due under or by reason of the Note
shall become immediately due and payable at Secured Party's option without
notice to Debtor, and Secured Party may proceed to enforce payment of same and
exercise any and all rights and remedies granted to it herein and in the Note,
and in any other instrument or agreement securing, evidencing or relating
thereto, and all rights and remedies available under any applicable law,
including the Washington Uniform Commercial Code, RCW 62A in force as of the
date hereof without limiting the generality of the foregoing, Secured Party
shall have any or all of the following rights and remedies:

                                       2
<PAGE>   31
            (a) At Secured Party's request, Debtor shall assemble the Collateral
and make it available to Secured Party at a place Secured Party designates which
is reasonably convenient to both parties;

            (b) Debtor agrees to put Secured Party into immediate possession of
the Collateral upon demand;

            (e) All payments received by Debtor under or in connection with any
of the Collateral shall, at Secured Party's election, be deposited in a
segregated FDIC-insured bank account in trust for the sole benefit of Secured
Party, or immediately upon receipt by Debtor or Secured Party, turned over to
Secured Party, in the same form as received (duly endorsed in favor of Secured
Party if and as required in its discretion);

            (d) Secured Party is authorized, without notice, demand or legal
proceedings, to enter any premises where the Collateral is situated and take
possession of, keep, store or remove any of the Collateral, and remain, or cause
a custodian of its choice to remain, on the premises in exclusive control
thereof without charge so long as Secured Party deems it reasonably necessary to
complete the enforcement of its rights hereunder or under the Note; provided
that should Secured Party seek to take possession of any of the Collateral by
court process, Debtor hereby irrevocably waives (i) any bond, surety or security
relating thereto required by any statute, court rule or otherwise is an incident
to such possession, (ii) any demand for possession prior to commencement of such
court process, and (iii) any requirement that Secured Party retain possession of
and not dispose of any such Collateral until after trial or final judgment;

            (e) Demand payment of, and collect, any accounts and general
intangibles comprising Collateral and, in connection therewith, Debtor
irrevocably authorizes Secured Party to endorse or sign Debtor's name, as
pertinent, on all collections, receipts, instruments and other documents as
required in its discretion, to take possession of and open mail addressed to
Debtor and remove therefrom payments made with respect to any item of the
Collateral or proceeds thereof, and, in Secured Party's sole discretion, to
grant extensions of time to pay, compromise claims and settle accounts and the
like for less than face value;

            (f) Demand and receive possession of any of Debtor's federal and
state taxes and the books and records utilized in the preparation thereof or
referring thereto; and

            (g) Debtor shall pay on demand all expenses actually incurred by
Secured Party in protecting, realizing upon, repossessing, and selling the
Collateral, or in interpreting or enforcing its rights hereunder, including
Secured Party's court costs and actual attorneys' fees incurred in both trial
and appellate courts (including all fees and costs incurred in any bankruptcy
court hearings of any kind whatsoever, including relief from stay proceedings,
disclosure statement and plan confirmation proceedings, nondischargeability
proceedings, claim objection proceedings, adversary proceedings, and
investigating, preparing and filing proofs of claims), or fees or costs incurred
without suit. The covenant to pay the sums as provided in this subparagraph 7(g)
shall be secured by this Security Agreement.

                                       3
<PAGE>   32
        8. APPOINTMENT AS ATTORNEY-IN-FACT. Debtor hereby irrevocably
constitutes and appoints Secured Party, and any officer or agent thereof, with
full power and substitution, as its true and lawful Attorney-in-Fact with full
irrevocable power and authority in their place and stead or in Secured Party's
own name, from time to time in Secured Party's discretion, for the purpose of
carrying out the terms of this Security Agreement and the Note and other
instruments executed in connection herewith, to take any and all appropriate
actions and to execute all documents and instruments which may be necessary or
desirable in Secured Party's opinion to accomplish the purposes of such
documents and, without limiting the generality of the foregoing, hereby give
Secured Party the power and right, on behalf of Debtor, without notice to or
assent by it, upon a default hereunder or under the Note, to: (i) ask, demand,
collect, receive and give acquittances and receipt for any and all monies due
and to become due under any Collateral, (ii) in the name of Debtor or in its own
name, or otherwise, take possession of and endorse and collect any checks,
drafts, notes, acceptances or other instruments for the payment of monies due
under or by reason of any Collateral, (iii) grant extensions of time to pay,
compromise and settle claims, accounts and general intangibles for less than
face value and execute all releases and other documents in connection therewith,
(iv) file any claim or commence and prosecute any action or proceeding in any
court of law or equity or take any other action deemed appropriate by Secured
Party for the purpose of collecting any and all such monies due in respect of
any Collateral whenever payable and to enforce any other right in respect
thereof; (v) direct any party liable for any payment in respect of any of the,
Collateral to make such payment directly to Secured Party or as it shall direct;
(vi) sign and endorse any invoices, freight or express bills, bills of lading,
storage or warehouse receipts, assignments and notices in connection with
accounts and other documents relating to the Collateral; (vii) defend any suit,
action or proceeding brought against Debtor with respect to any Collateral;
(viii) generally to sell, transfer pledge, or otherwise deal with any of the
Collateral as fully as though Secured Party were the absolute owner thereof for
all purposes, and to do, at Secured Party's option and Debtor's expense, from
time to time all acts and things which Secured Party deems necessary to protect,
preserve or realize upon the Collateral and Secured Party's rights and interests
to, in and under the Collateral.

        This power of attorney is a power coupled with an interest and shall be
irrevocable. The powers conferred upon Secured Party hereunder are solely to
protect its rights and interests in, to and under the Collateral and shall not
impose any duty upon it to exercise any such powers. Secured Party shall be
accountable only for amounts that are actually received as a result of the
exercise of such powers, and neither it nor any of its officers, directors,
shareholders, employees, or, agents shall be responsible to Debtor for any act
or omission whatsoever.

        Debtor hereby authorizes Secured Party, from time to time, (i) to
communicate directly in its own name with any party who is obligated to Debtor
with regard to the assignment and collection of such obligation and other
matters relating thereto, and (ii) to execute any endorsements, assignments or
other instruments of conveyance or transfer with respect to the Collateral in
connection with any sale or other conveyance or transfer thereof pursuant to
section 7 above.

        9. TAX INDEMNIFICATION. Debtor agrees to pay, and to defend, save and
hold Secured Party harmless from and against any and all liabilities with
respect to, or resulting from any

                                       4
<PAGE>   33
delay in paying any excise, sales or other taxes which may be payable or
determined to be payable with respect to any of the Collateral or in connection
with any of the transactions contemplated by this Security Agreement.

        10. NOTICE. Any notice given pursuant to this Security Agreement shall
be effective when mailed, postage prepaid, by certified or registered mail
(return receipt requested), or by personal service, at the following addresses:

            Notice to Debtor:          Northwest Biotherapeutics LLC
                                       Attn: Chair of the Board of Managers
                                       120 Northgate Plaza, Suite 205
                                       Seattle, WA 98125

            Notice to Secured Party:   Northwest Hospital
                                       Attn: Chief Executive Officer
                                       1550 North 115th Street
                                       Seattle, WA 98133

        11. MISCELLANEOUS.

            (a) Waiver. This Security Agreement shall not be qualified or
supplemented by course of dealing. No waiver or modification by Secured Party of
any of the terms or conditions hereof shall be effective unless in writing
signed by Secured Party. No waiver nor indulgence by Secured Party as to any
required performance by Debtor shall constitute a waiver as to any subsequent
required performance or other obligations of Debtor hereunder.

            (b) Benefit. This Agreement shall be binding upon, and inure to
the benefit of, the respective legal representatives, successors and assigns of
the parties hereto.

            (c) Construction. This Agreement is being executed and delivered
and is intended to be performed in the State of Washington, and shall be
construed and enforced in accordance with the laws of that state.

            (d) Venue. The parties agree the venue of any suit or action
between the parties will be in the Superior Court for King County, Seattle,
Washington.

            (e) Severability. Should any provision of this Agreement be held
by any court of competent jurisdiction to be void or unenforceable, such defect
shall not affect the remainder of this Agreement, which shall continue in full
force and effect.

            (f) Counterparts: Facsimile Copies. This Agreement may be executed
in one or more counterparts, each of which shall be deemed an original, but all
of which together shall constitute one and the same instrument. Facsimile copies
hereof may be executed as counterpart originals.

                                       5
<PAGE>   34
            (g) Termination of Security Interest. When all sums owed Secured
Party have been paid and all Obligations of Debtor fulfilled under this
Agreement and the Note, Security Party will prepare, sign and file appropriate
UCC-3 Termination Statements.

        SIGNED effective July 1, 1997.

DEBTOR:                                     SECURED PARTY:

NORTHWEST BIOTHERAPEUTICS LLC               NORTHWEST HOSPITAL

By                                          By
    ------------------------------------       ---------------------------------

    Its                                       Its
        --------------------------------          ------------------------------

                                       6<PAGE>   1
                                                                   EXHIBIT 10.10

                         MASTER NOTE FOR LINE OF CREDIT

$2,900,000.00                                                       July 1, 1997
                                                             Seattle, Washington

        This Note is given to evidence the obligation of Northwest
Biotherapeutics LLC ("Borrowee") to repay all sums that Northwest Hospital
("Lendee") may from time to time advance to Borrower ("Advances") under a line
of credit up to a total amount of $2,900,000 (the "Credit Line").

        FOR VALUE RECEIVED, Borrower promises to pay to the order of Lender the
total unpaid principal balance of all Advances ("'Principal Balance"), together
with interest on all such Advances at the rate specified below ("Note Rate"),
together with all other sums due under this Note.

        1. INTEREST. The Note Rate shall at all times be equal to 1.0% above the
large business prime lending rate of Bank of America NW, N.A., doing business as
Seafirst Bank (the "Prime Rate"), as amended from time to time. The Note Rate
shall be adjusted automatically on the same day as any change in the Prime Rate.
All interest will be calculated at the per annum rate based on a 360-day year
and applied to the actual number of days elapsed.

        2. PAYMENTS. This Note shall be repaid in full upon the receipt by
Borrower of the proceeds of any equity financing, including any private
placement or other securities offering, which financing efforts Borrower shall
diligently pursue using its best efforts. No installment payments shall be
required, provided that Borrower may prepay all or any portion of the sums due
under this Note at any time without penalty. At the option of Lender, payments
will be applied first to interest, then to principal, and last to any late or
collection charges, including attorneys' fees and costs.

        The Principal Balance, all unpaid accrued interest, any unpaid fees, and
any other amounts owing hereunder shall be due and payable in full on June 30,
2000.

        3. SECURITY. This Note shall be secured by a security interest in
certain assets of Borrower ("Collateral") as more particularly set forth in the
Security Agreement and UCC-1 Financing Statement executed concurrently herewith
by Borrower.

        4. ADVANCES. Advances under this Note must be requested by Borrower in
writing and shall be subject to the following terms and conditions:

               4.1 LENDER DISCRETION. All Advances requested by Borrower shall
be subject to the approval of Lender which may be granted or withheld in
Lender's sole discretion or made subject to such additional terms and conditions
as Lender may determine in its sole discretion.

               4.2 AUTHORIZED PARTIES. Only Gerald P. Murphy, M.D., on behalf of
Borrower, shall be authorized to request Advances under this Note. This
authority to request
<PAGE>   2

Advances shall continue until the Lender receives notice in writing of the
revocation or cancellation of authority.

               4.3 REQUIREMENTS FOR REQUEST. Each request for an Advance shall
be made at least thirty (30) full business days prior to the time Borrower
expects Lender to make such Advance. The written request must include, at a
minimum, the following information in a format and substance acceptable to
Lender: (1) a detailed description of the proposed uses of the proceeds of the
Advance, (2) a revised budget for Borrower, updated as of the date of the
request, and (3) a detailed statement of the status of Borrower's equity
financing efforts.

               4.4 PROCEDURE FOR ADVANCES. All Advances shall be made at
Lender's election, by the issuance of Lender's check to Borrower or by
electronic funds transfer to Borrower's account as designated by Borrower to
Lender.

               4.5 MINIMUM SECURITY. Lender shall have no obligation to make any
Advance hereunder unless the value of the Collateral under the Security
Agreement and UCC-1 Financing Statement at the time of the Advance equals or
exceeds the value of the Collateral as of the date of this Note.

               4.6 LIMITS. The amount each Advance shall constitute a portion of
the Principal Balance and the sum of all Advances, whether repaid or not prior
to future Advances, shall not exceed $2.9 million dollars. This is not a
revolving line of credit.

        5. USE OF ADVANCES. Borrower represents and warrants that all Advances
will be used primarily for business, commercial, or investment purposes, as
defined in RCW 19.52.080 (exemption from usury), and in furtherance of
Borrower's business purposes as detailed in Borrower's written request for such
Advance.

        6. EVIDENCE OF AMOUNTS OWING. Borrower agrees that the Principal
Balance, the interest due thereon, and any applicable fees shall be evidenced by
Lender's records, which records shall be the sole criteria for computation of
principal, interest, and fee balances owed Lender by Borrower.

        7. DEFAULT. The occurrence of any of the following shall constitute an
"Event of Default" hereunder: (a) Borrower's failure to make any payment of
principal, interest, or fees when due hereunder, (b) a material adverse change
in the financial condition of Borrower; (c) any untrue statement made by
Borrower in connection with any request for an Advance, or (d) Borrower's
insolvency or a bankruptcy filing by Borrower.

        8. ACCELERATION. Upon the occurrence of any Event of Default, Lender
shall have no further obligation to make any Advances hereunder and the
Principal Balance and all unpaid interest and any fees may be declared
immediately due and payable, without notice, at the option of Lender.

        9. COLLECTION COSTS. Borrower and every other person or entity at any
time liable for the payment of the indebtedness evidenced by this Note shall
also be liable for all

                                       2
<PAGE>   3

costs, expenses, and fees incurred by Lender in collecting any amounts owing
hereunder, including reasonable attorney's fees. Any judgment obtained by Lender
shall bear interest at a rate of 18% per annum or 2% per annum above the Note
Rate, whichever is greater.

        10. WAIVERS. For value received, each party signing or endorsing this
Note waives presentment, demand, protest, and notice of nonpayment and agrees to
be bound as a principal and not as a surety and promises to pay all costs oil
collection, including reasonable attorneys' fees, whether or not suit is
commenced.

        11. CHOICE OF FORUM/APPLICABLE LAW. In case of suit to enforce the terms
of this Note, Borrower consents to the personal jurisdiction of the Washington
courts and the federal courts located in the State of Washington. At the option
of the holder of this Note, venue may be in King County, Washington. This Note
and the Security Agreement shall be construed and enforced in accordance with
the laws of the state of Washington, without regard to that state's choice of
law rules.

        ORAL AGREEMENTS OR ORAL COMMITMENTS TO LOAN MONEY, EXTEND CREDIT, OR TO
FORBEAR FROM ENFORCING REPAYMENT OF A DEBT ARE NOT ENFORCEABLE UNDER WASHINGTON
LAW.

                                          NORTHWEST BIOTHERAPEUTICS LLC

                                          By     /s/ George P. Hutchinson
                                             -----------------------------------
                                             Its
                                                 -------------------------------

                                       3

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