Document:

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                                                                   Exhibit 10.10

                      FIRST AMENDMENT TO AGREEMENT OF LEASE

         This FIRST AMENDMENT TO AGREEMENT OF LEASE ("First Amendment") is made
and entered into as of the 22nd day of June, 2000 at Boston, Suffolk County,
Commonwealth of Massachusetts, by and between Joseph Biotti, Jr. and Francis
Biotti, Trustees of One Nevada Realty Trust under Declaration of Trust dated
September 14, 1984 and filed for registration with Middlesex South Registry
District of the Land Court as Document No. 667834 and their heirs, executors,
successors and assigns where the context so admits ("Lessor") and Matritech,
Inc. a Delaware corporation and its successors, legal representatives and
assigns where the context so admits ("Lessee").

                         W I T N E S S E T H   T H A T

         Whereas, Lessor and Lessee entered into an Agreement of Lease (the "330
NEVADA STREET LEASE"), dated as of the 6th day of October, 1995, with respect to
approximately 22,500 square feet of space, more or less, on the second floor of
the building known as numbered as 330 Nevada Street, Newtonville, Massachusetts
02460 (the "330 NEVADA STREET BUILDING");

         Whereas, Lessee had no options under the 330 Nevada Street Lease to
extend its tenancy;

         Whereas, the Lessee desires to extend the 330 Nevada Street Lease for
one five (5) year period and the Lessor, in accordance with the terms of this
First Amendment is willing to do so and both Lessee and Lessor seek to
memorialize the terms of their agreement pertaining to such extension of the 330
NEVADA STREET LEASE, as set forth herein:

         Whereas, all other parties which had an interest to lease the Premises
after Lessee's current tenancy expires have waived their rights to lease the
Premises;

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         NOW, THEREFORE, Lessor and Lessee, for and in consideration of the
mutual covenants hereinafter contained, agree as follows, effective January 1,
2001:

         1.       Term: Article I, paragraph A is hereby modified by replacing
                  the last line thereof with the following:

                       "shall end on December 31, 2005."

         2.       Annual Rental: Article I, paragraph C is hereby deleted in its
                  entirety and the following is substituted therefor:

                       "The annual rental for each year of the Term shall be
                       four hundred five thousand dollars ($405,000.00) for the
                       demised premises ($33,750 per month)."

         3.       Monthly Rental Installment: That certain reference in Article
                  IV, paragraph A(1) of "$19,218.75" is hereby changed to
                  "$33,750.00".

         4.       Security Deposit: The principal amount of the security deposit
                  presently in place under the Agreement pursuant to Article I,
                  paragraph D is $57,656.25 (which is equal to three months'
                  rent at $19,218.75) (the "Existing Security Principal"). On or
                  before January 1, 2001, Lessee agrees to add $21,000.00 to the
                  Existing Security Principal at which point the total Principal
                  Security Deposit will be $78,656.25.

         5.       Notices: Article I, paragraph (E)(1), subpart (a.) is hereby
                  changed as follows:

                  a.       If to Lessor, to 320 Nevada Street, Newtonville,
                           Massachusetts 02460, with a copy to Loyd M. Starrett,
                           Esq., Mahoney, Hawkes & Goldings, LLP, 75 Park Plaza,
                           Boston, MA 02116.

         6.       Repairs and Maintenance: Without in any manner expanding
                  Lessor's maintenance and/or repair obligations under the 330
                  Nevada Street Lease, Lessor and Lessee agree that the
                  following improvements and additions shall be made: (a)
                  addition of limited additional air conditioning to the
                  Premises; (b) replacement of rugs in certain areas of the
                  Premises; and (c) painting of certain portions of the
                  Premises. Lessor shall not in

                                      -2-
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                           any event be responsible for more than Twenty Seven
                           Thousand Five Hundred Dollars ($27,500.00) of the
                           total cost of these three items with the balance to
                           be paid by Lessee. Lessee and Lessor will each obtain
                           quotes for each of the three items. Lessee and Lessor
                           then will agree on the vendor that is providing the
                           services in each instance.

                  7.       Assignment and or Subletting: Article V, paragraph
                           A.12 is hereby amended by deleting lines 25 through
                           36 and substituting the following:

                                 "letting of the Premises resulting in payments
                                 to Lessee in excess of $18.00 per square foot,
                                 Lessor and Lessee shall divide equally the
                                 amount by which such payments exceed the sum of
                                 $18.00 per square foot and expenses actually
                                 incurred by lessee for broker's commission,
                                 reasonable attorney's fees and renovations to
                                 effectuate such assignment or subletting."

                  8.       Option: Lessee shall have one (1) option to extend
                           the 330 Nevada Street Lease with respect to the
                           Premises for one (1) five (5) year period (the
                           "Option"), commencing on January 1, 2006, provided
                           the Lessee is not then in uncured default, which
                           Option may be exercised only for all of Lessee's
                           space, and no subportion thereof, and only by giving
                           written notice thereof to Lessor not later than
                           January 1, 2005. All other terms and conditions of
                           the 330 Nevada Street Lease, unless otherwise agreed
                           in writing, shall apply to the Option Term. The
                           parties will execute a mutually agreeable amendment
                           to the 330 Nevada Street Lease in the event the
                           Option is exercised.

                  9.       Annual Rent During Option Period: The annual rent
                           during the Option Term shall be an amount equal to
                           the fair market rental value of the Premises as of
                           January 1, 2006. Such fair market rental value shall
                           be determined by mutual agreement or as provided in
                           this paragraph. In no event shall the fair market
                           rental value be less than $18.00

                                      -3-
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                           per square foot; if the parties are not able to agree
                           to the amount of fair market rental value and
                           appraisal pursuant to this paragraph yields an amount
                           less than $18.00 per square foot, then the parties
                           agree that the fair market rental value shall be
                           $18.00 per square foot. Upon Lessee's notification to
                           lessor that it desires to exercise its Option, Lessor
                           and Lessee shall promptly confer and attempt to agree
                           upon the fair market rental for the Option Term. If
                           Lessor and Lessee fail to agree on such amounts by
                           March 1, 2005, the fair market rental value shall be
                           appraised by a competent and experienced
                           disinterested person selected by Lessor and
                           reasonably satisfactory to Lessee. All costs
                           associated with such appraisal shall be borne by
                           Lessor. Lessor shall notify Lessee of the fair market
                           rental value according to that appraisal no later
                           than May 1, 2005. Said appraised rental value shall
                           be deemed to be the fair market rental value for the
                           Option Term unless Lessee notifies Lessor of its
                           disagreement with such value in writing within ten
                           (10) days after receipt of the appraisal, and Lessee
                           furnishes to Lessor an appraisal rental value by a
                           competent and experienced disinterested person
                           selected by Lessee and reasonably satisfactory to
                           Lessor no later than July 1, 2005. All costs
                           associated with such appraisal shall be borne by
                           Lessee. If the difference between the higher
                           appraisal and the lower appraisal does not exceed ten
                           percent (10%) of the lower appraisal, the average of
                           the two appraisals shall be deemed to be the fair
                           market rental value. If the difference between the
                           higher appraisal and the lower appraisal does exceed
                           ten percent (10%) of the lower appraisal, then a
                           competent and experienced disinterested person shall
                           be appointed as a third appraiser by mutual agreement
                           of the Lessor and Lessee no later than September 1,
                           2005. The third appraiser shall make his or her
                           appraisal of rental value

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                           of the Premises by November 1, 2005, and the average
                           of the two closest appraisals shall then be deemed to
                           be the fair market rental for the Option Term. All
                           costs associated with such third appraisal shall be
                           shared equally by Lessor and Lessee.

                  10.      Broker: Lessor and Lessee each warrant to the other
                           that it has had no dealings with any broker or agent
                           in connection with this First Amendment, and agree to
                           hold harmless and indemnify the other party from and
                           against any and all costs (including, without
                           limitation, attorney's fees for defense of an
                           action), expenses or liability for any compensation,
                           commissions or charges claimed by such a broker or
                           agent.

                  11.      Expansion Notices: Lessor has no obligation to notify
                           Lessee of any space that becomes available in the
                           Building and Article III, paragraph D is deleted in
                           its entirety.

                  12.      Waiver: Lessee hereby waives any and all claims and
                           releases Lessor from any and all liability with
                           respect to any cause of action Lessee has or may have
                           as detailed in that certain letter from Lessee to
                           Lessor dated January 7, 2000, or otherwise.

                  13.      No Other Rights: Lessor represents and warrants to
                           Lessee that all parties which have or had an interest
                           or right to lease the Premises after Lessee's current
                           tenancy expires have waived their rights to lease the
                           Premises.

                  14.      330 Nevada Street Lease: All terms and conditions of
                           the 330 NEVADA STREET LEASE not specifically changed
                           by this First Amendment to the Lease shall remain in
                           full force and effect.

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IN WITNESS WHEREOF, the said parties hereunto set their hands and seals as of
the date first set forth above.

LESSEE                                        LESSOR
MATRITECH, INC.                               ONE NEVADA REALTY TRUST

/s/  Stephen D. Chubb                         /s/  Joseph Biotti, Jr.
----------------------------------            ---------------------------------
Stephen D. Chubb, CEO and Chairman            Joseph Biotti, Jr., Trustee
Thereunto Duly Authorized                     Thereunto Duly Authorized

/s/  David L. Corbet                          /s/  Francis L. Biotti
----------------------------------            ---------------------------------
David L. Corbet, President and COO            Francis L. Biotti, Trustee
Thereunto Duly Authorized                     Thereunto Duly Authorized

                                      -6-<PAGE>   1

                                  Exhibit 10.17

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     For the Sparkasse [Savings Bank]               Sparkasse               1/99
                                                    Freiburg - Northern Breisgau
Loan with initial fixed interest                    P.O. Box 11 70
to legal entities or for commercial or independent  79011 Freiburg
professional purposes already exercised             FKA/035/ADL/BR
                                                    -Sparkasse-
                                                    Account no.       6000316396
                                                    Date   Freiburg, May 7, 1999
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ADL Vertriebs GmbH Gesellschaft fur
Allergie, Diaknostika und Laborkonzepte
Jechtinger Strasse 9
79111 Freiburg
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- hereinafter called the Borrower - receive(s) from the Sparkasse under the
following terms a

          loan for the nominal amount of 380,000.00 DM
2

Account to be credited:   1 002 038 6         Account to be debited: 1 002 038 6

1  COSTS OF LOAN, REPAYMENT
1.1 INTEREST: The loan is subject to interest at 5.200 percent per year. This
interest rate is unchanging until May 30, 2004. No earlier than six weeks, no
later than two weeks before the end of the fixed interest period either party
can request that the terms for granting of the loan (interest rate, disagio,
etc.) be renegotiated. If no new loan conditions are agreed to before the end of
the fixed interest period, the loan will continue under terms subject to change.
The interest rate set by the Sparkasse for loans of this type shall apply. If
market conditions change, the Sparkasse has the right to lower or raise the
interest effective immediately by declaration to the Borrower.

1.2 The Sparkasse will impose a disagio of        percent and a one-time
processing commission of       percent of the loan amount. The two amounts will
be charged by the Sparkasse upon the first payout. In the event of early
repayment of the loan, the processing commission will not be refunded - not even
in part. The disagio will be charged as follows:

1.3 OTHER COSTS: All costs which arise as a result of the conclusion and
execution of this contract, including the furnishing of collateral, shall be
borne by the Borrower.

1.4 PROVISION, NON-ACCEPTANCE: The Borrower is obligated to prepare the
conditions for payout and to receive the loan. Starting on November 1, 1999 the
Sparkasse has the right to charge provision interest of 3.00 percent per year
for the amount of the loan not used. If the payout ultimately does not come
about for a reason for which the Sparkasse is not responsible, it retains all of
its contractual and legal rights. Even in this case the provision commission
will be charged. This also applies even if the Sparkasse make use of its rights
in accordance with No. 9.3.

1.5 REPAYMENT AND PAYMENT DEADLINES: All amounts due for payment well be debited
from the debit account designated above. INTEREST is due for the first time on
the payment date following the first payout, PRINCIPAL PAYMENTS for the first
time on June 30, 1999.
Redemption loans: Repayment 17.55 percent per year of the face value of the loan
plus the interest saved by the repayment.

The annual payment (interest plus principal) is at present 86,471.28 DM. It is
to be paid in installments of (1) 7,205.94 DM on/at the end of the month. Until
the beginning of repayment, only the interest is to be paid on these dates. If
there is a change in the interest rate (No. 1.1), the Sparkasse can also adjust
the payment amount.

Installment loans:  Annual repayment(1)    in installments of(1)           on/at
                 .  The interest is to be paid in installments on/at           .

Fixed loans:        The loan is to be repaid on/at      . The interest is to be
                    paid in installments on/at                                 .

1.6 If the borrower does not make a payment when it is due, the Sparkasse can
charge for its damages from the delay without jeopardizing additional claims.

2  SPECIAL PROVISIONS

The costs of the loan statement in the amount of DM 20.00 per year shall be
borne by the borrower. Also applicable are the conditions named in Appendices 1,
2 and 3, which are a material part of this loan agreement.

3  COLLATERAL
The loan cannot be drawn upon until all of the prerequisites are fulfilled so
that the agreed-upon collateral is available to the Sparkasse, and the Sparkasse
has verification thereof, if appropriate. The following collateral is provided
to the Sparkasse in special documents, irrespective of the liability of any
already existing or future collateral in conjunction with the collateral purpose
thereof:

-    Security assignment of merchandise stock; provider of collateral: ADL
     Vertriebs GmbH
-    Assignment of accounts receivable, blanket assignment from A to Z; provider
     of collateral: ADL Vertriebs GmbH
-    Assignment of the rights and claims of a term life insurance policy for
     DM 300,000.00; insured: Franz Maier
-    Indemnity bond of the Burgschaftsbank Baden-Wurttemberg GmbH for
     DM 266,000.00
-    Absolute guaranty from Mr. Franz Maier for DM 350,000.00
-    Absolute guaranty from Mr. Joachim Helver for DM 120,000.00
-    Absolute guaranty from Ms. Eva Heidt for DM 120,000.00
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                                  Exhibit 10.17
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4 SPECIAL TERMS OF PAYOUT FOR CONSTRUCTION FINANCING
4.1 The loan will be disbursed if the audit of the documents which are still to
be submitted to the Sparkasse so permit. To test the condition for disbursement
of the loan, the Sparkasse has the right to have an inspection and appraisal of
the mortgaged property performed at the Borrower's expense.
4.2 At the option of the Sparkasse, depending on the progress of the
construction work partial payments can be made, as long as the conditions for
disbursement are satisfied. Care must be taken to ensure that the construction
project can be completed with the funds still available. As a rule the Sparkasse
will make partial payments only after all outside and inside funds have been
used and after the shell construction is complete.

5 LIMITATION OF ASSIGNMENT
The claim for disbursement of the loan can only be assigned or pledged with the
consent of the Sparkasse.

6 MULTIPLE BORROWERS, RETRANSFER OF COLLATERAL
In the case of multiple borrowers, each is entitled separately to receive the
loan. Multiple borrowers are liable as co-debtors, including liability for any
overdraft of the giro account of one of the borrowers due to debiting of the
installment charges.
If the Sparkasse is satisfied by one of the borrowers, it does not test whether
the latter is entitled to items of collateral which it no longer requires. In
principle it will return such collateral to the provider of the collateral, if
the borrower who makes the payment does not prove that the provider of the
collateral has approved having it turned over to him.

7 FULFILLMENT
All payments are to be paid or remitted - at no cost to the Sparkasse - in the
business premises of the Sparkasse or at a place to be designated by it. The
Sparkasse has the right to apply the payments to the amounts owed at its own
discretion, and if there are multiple debt relationships, can determine to which
debt relationship, and to which amounts owed, payments are to be applied.

8 DUTY OF DISCLOSURE AND NOTIFICATION
The Borrower must grant the Sparkasse, a fiduciary designated by it, or a
responsible auditing agency access at all times to examine the Borrower's
business circumstances, must in particular submit its books, balance sheets,
financial statements and business papers or must allow these procedures to be
examined and audited, must give all desired information and allow its operations
to be observed. The Sparkasse is required by law to have the business
circumstances of the Borrower disclosed to it.
AFTER CONSULTATION WITH THE BORROWER, THE SPARKASSE CAN REQUEST THE NECESSARY
DOCUMENTS AND INFORMATION DIRECTLY FROM THE BORROWER'S ACCOUNTING AND TAX
ADVISORS.
If the specified documents and information are stored on data media, the
Borrower is obligated to make them readable within a reasonable time.
THE SPARKASSE HAS THE RIGHT TO EXAMINE THE PUBLIC REGISTERS AND THE REAL ESTATE
REGISTER AND FILES AT ANY TIME AND TO REQUEST SIMPLE OR CERTIFIED COPIES AND
EXTRACTS AT THE BORROWER'S EXPENSE, AND TO OBTAIN INFORMATION FROM INSURANCE
COMPANIES, GOVERNMENT AGENCIES AND OTHER SOURCES WHICH IT MAY CONSIDER NECESSARY
FOR EVALUATING THE LOAN RELATIONSHIP.

9 CANCELLATION, ACCOUNT DUE IMMEDIATELY
9.1 The loan can be terminated in whole or in part by either side with one
month's notice, effective at the expiration of the first or a subsequent fixed
interest agreement in accordance with No. 1.1. If the loan is continued at a
variable interest rate after the expiration of the first or a subsequent fixed
interest agreement, it can be terminated at any time with three months' notice
to the other contracting party.

The cancellation is to be in writing. Termination by the Borrower will be
treated as null and void, if the Borrower does not pay back the amount owed
within two weeks after the effective date of the termination.

9.2 Irrespective of its right to cancel without advance notice for other
significant cause (No. 26 AGB), the Sparkasse can declare the principal due and
payable immediately,
-    if the provider of the collateral violates the special duties imposed upon
     it in the separate collateral agreement or land charge initiation
     documents;
-    if the Borrower violates the duties imposed upon it in No. 8;
-    if the Borrower falls more than 14 days behind with payments due, and also
     does not pay after an additional follow-up deadline of at least 14 days has
     been set by the Sparkasse;
-    if forced sale or forced administration is initiated with respect to the
     encumbered collateral property or parts thereof; the case of forced sale
     because of conflict between co-owners or co-holders of hereditary building
     rights is excluded;
-    if accessory items, rents or lease charges are attached, or if they are
     disposed of without the consent of the Sparkasse, unless the disposal of
     the accessory items takes place within the bounds of proper business;
-    if the pledged property is sold in whole or in part, or is otherwise
     disposed of, without the consent of the Sparkasse, or if, in the case of a
     hereditary building right, the owner of the land makes use of its right of
     reversion;
-    if the legal validity or the priority of the land charge is disputed, or
     the agreed-upon priority is not procured within two months.

9.3 THE SPARKASSE HAS THE RIGHT TO REFUSE TO DISBURSE THE LOAN, OR TO DECLARE
AMOUNTS WHICH HAVE ALREADY BEEN PAID OUT IMMEDIATELY DUE AND PAYABLE, IF
-    the information contained in the loan documents turns out to be incorrect
     or if significant changes occur in the personal and business circumstances
     of the Borrower or the provider of collateral, in particular if the overall
     financing of the building project is no longer assured or completion
     appears threatened for other reasons,
-    the right to disbursement of the loan is attached.
If there are multiple borrowers or providers of collateral, the provisions
stated above under 9.1 to 9.3 apply even if the conditions for cancellation
recall of the loan reside in the person of only one borrower or provider of
collateral.

10 PLACE OF JURISDICTION
If the place of jurisdiction is not determined by the encumbered parcel of land,
and the authority of the general place of jurisdiction is not already evident
from ss. 10 ZPO (Code of Civil Procedure), the Sparkasse can pursue its claims
at its general place of jurisdiction, if the contracting partner to be sued is a
Kaufmann [specially defined entrepreneur under German law - Transl.] or a legal
entity in the meaning of No. 6 AGB [General Business Terms and Conditions], or
has no general place of jurisdiction in Germany at the time of entering into the
contract, or later relocates his residence or usual whereabouts outside of the
Federal Republic of Germany, or if his place of residence or usual whereabouts
are not known at the time the action is brought.

11 CONSENT TO DISCLOSURE OF INFORMATION IN CONJUNCTION WITH REFINANCING
The Borrower consents to the Sparkasse conveying to a central bank or a
refinancing bank (refinancing institute) the necessary information (such as
amount of loan, due date, name and address of the Borrower), if the Sparkasse
assigns or pledges the loan receivable to a refinancing institute or uses it for
refinancing on the basis of some other legal instrument.

12 GENERAL BUSINESS TERMS AND CONDITIONS
The Sparkasse specifically points out that in addition, its General Business
Terms and Conditions (AGB) are part of the contract. The AGB are available for
review in the counter hall of the Sparkasse.

The contract and the copy/copies are to be signed by all of the borrowers named
on the front!
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Note: if a jointly liable borrower is a consumer in the meaning of ss.1
VerbrKrG, form 191 050.000 is also required.

City, date                                            (if different from Page 1)
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Freiburg, May 31, 1999
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Verification of identity
--------------------------------------------------------------------------------
Person 2 known & already verified under account_____________
Identified by   __Personal Identity Card   __Passport
No._______________________________________ issued by

--------------------------------------------------------------------------------
Person 2 known & already verified under account_____________
Identified by   __Personal Identity Card   __Passport
No._______________________________________ issued by

--------------------------------------------------------------------------------
Identity checked              Signature of the preparer (with ID no.)
and for the
correctness of the
signature(s):
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Company name and signature(s) of Borrower(s)
--------------------------------------------------------------------------------
The borrower(s) is/are acting on own account:
__ Yes   __ No

                                   Franz Maier

ADL Vertriebs GmbH Gesellschaft fur Allergie, Diaknostika und Laborkonzepte

For the Sparkasse:
--------------------------------------------------------------------------------
Sparkasse
Freiburg - Northern Breisgau
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(1)  Each party to the contract will receive a copy of the AGB, if there is no
     prior business relationship and the contract is concluded outside of the
     Sparkasse.

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