<PAGE>
                                                                   EXHIBIT 10.28


                        RCPI Landmark Properties, L.L.C.
                      c/o Tishman Speyer Properties, L.P.
                              45 Rockefeller Plaza
                            New York, New York 10111

                                                        February 16, 2006

Antigenics, Inc.
630 Fifth Avenue
New York, New York 10011

Omrix Biopharmaceuticals Inc.
708 Third Avenue
New York, New York 10017

          RE:  CONSENT TO SUBLEASE

"Building":      630 Fifth Avenue, New York, New York 10011.

"Premises"       Space on the 21st and 22nd floors of the Building.

"Sublet Space":  A portion of the Premises located on the 22nd floor of the
                 Building.

"Landlord":      RCPI Landmark Properties, L.L.C.

"Sublandlord":   Antigenics, Inc., a Delaware Corporation.

"Subtenant":     Omrix Biopharmaceuticals Inc., a Delaware Corporation.

"Lease":         Lease dated December 6, 1995, between Landlord's
                 predecessor-in-interest, Rockefeller Center Properties, as
                 landlord, and Sublandlord's predecessor-in-interest, GHA
                 Management Corporation, as tenant, as same has been and may
                 hereafter be amended, modified, extended or restated from time
                 to time.

"Sublease":      Sublease dated February 2, 2006 between Sublandlord and
                 Subtenant, as attached hereto, as same may be amended,
                 modified, extended or restated from time to time, as may be
                 permitted hereunder.

Ladies/Gentlemen:

     You have requested Landlord's consent to the sublease of the Sublet Space.
Such consent is hereby granted on the terms and conditions, and in reliance upon
the representations and warranties, set forth in this letter (this "Agreement").

     1. Sublandlord represents and warrants to Landlord that (a) the Lease is in
full force and effect; (b) the Lease has not been assigned, encumbered,
modified, extended or supplemented; (c) Sublandlord knows of no defense or
counterclaim to the enforcement of the Lease; (d) Sublandlord is not entitled to
any reduction, offset or abatement of the rent payable


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under the Lease; (e) Sublandlord, to the best of its knowledge, is not in
default of any of its obligations or covenants, and has not breached any of its
representations or warranties, under the Lease; (f) Landlord has paid all
amounts and performed all work required to be paid or performed under the Lease
in connection with the initial occupancy of the Premises under the Lease; and
(g) Landlord, to the best of Sublandlord's knowledge, is not in default of any
of its obligations or covenants under the Lease.

     2. Sublandlord and Subtenant each represents and warrants to Landlord that
(a) the Sublease constitutes the complete agreement between Sublandlord and
Subtenant with respect to the subject matter thereof; (b) a true and complete
copy of the Sublease is attached hereto; and (c) no rent or other consideration
is being paid to Sublandlord by Subtenant for the Sublease or for the use, sale
or rental of Sublandlord's fixtures, leasehold improvements, equipment,
furniture or other personal property except as set forth in the Sublease.

     3. The Sublease shall be subject and subordinate to the Lease and this
Agreement. Neither Sublandlord nor Subtenant shall take, permit or suffer any
action which would violate the provisions of the Lease or this Agreement.

     4. Landlord's obligations to Sublandlord are governed only by the Lease and
this Agreement. Landlord's obligations to Subtenant are only as expressly
provided in this Agreement. Landlord shall not be bound or estopped by any
provision of the Sublease, including any provision purporting to impose any
obligations upon Landlord (except as provided in Paragraph 7 of this Agreement).
Nothing contained herein shall be construed as a consent to, approval of, or
ratification by Landlord of, any of the particular provisions of the Sublease or
any plan or drawing referred to or contained therein (except as may be expressly
approved herein). Landlord has not reviewed or approved any provision of the
Sublease. Notwithstanding anything to the contrary contained in the Sublease,
the term of the Sublease shall end no later than the day that is one day prior
to the expiration date of the Lease.

     5. If Sublandlord or Subtenant violates any of the terms of this Agreement,
or if any representation by Sublandlord or Subtenant in this Agreement is untrue
in any material respect, or if Subtenant takes any action which would constitute
a default under the Lease after the giving of notice and the expiration of any
grace period required under the Lease, then Landlord may declare the Lease to be
in default and avail itself of all remedies provided at law or equity or in the
Lease with respect to defaults.

     6. Subject to the provisions of Paragraph 7 of this Agreement, if the Lease
is terminated prior to the stated expiration date provided therein, the
Sublease, shall likewise terminate on the date of such termination. In
connection with such termination, Subtenant, at its sole expense, shall
surrender the Sublet Space to Landlord in the manner provided for in the Lease,
including the removal of all its personal property from the Sublet Space and
from any part of the Building to which it is not otherwise entitled to occupancy
and repair all resulting damage to the Sublet Space and the Building. Except as
otherwise provided in the Lease, Landlord shall have the right to retain any
property and personal effects which remain in the Sublet Space or the Building
on the date of termination of the Sublease, without any obligation or liability
to Subtenant, and to retain any net proceeds realized from the sale thereof,
without waiving Landlord's rights with respect to any default by Sublandlord
under the Lease or Subtenant under the foregoing provisions of this paragraph
and the provisions of the Lease and the Sublease. If Subtenant shall fail to
vacate and surrender the Sublet Space in accordance


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<PAGE>

with the provisions of this paragraph, Landlord shall be entitled to all of the
rights and remedies which are available to a landlord against a tenant holding
over after the expiration of a term, and any such holding over shall be deemed a
default under the Lease and a holding over by Sublandlord with respect to the
entire Premises under the Lease. In addition, Subtenant agrees that it will not
seek, and it expressly waives any right to seek, any stay of the prosecution of,
or the execution of any judgment awarded in, any action by Landlord to recover
possession of the Sublet Space. Subtenant may not vacate the Sublet Space on a
Saturday, Sunday or a holiday. If the Sublease terminates on a Saturday, Sunday
or a holiday, Subtenant must comply with this paragraph by the end of the
preceding Business Day. This paragraph shall survive the earlier termination of
the Lease and the Sublease.

     7. If the Lease is terminated before the stated expiration date of the
Sublease, and if Landlord or any other party then entitled to possession of the
Sublet Space so notifies Subtenant, Subtenant, at Landlord's option, shall
attorn to Landlord or any such party for the remainder of the stated term of the
Sublease for the Sublet Space under all the terms and conditions of the Lease,
except that the fixed rent and any additional rent payable by Subtenant to
Landlord pursuant to the Lease (collectively, the "Rent") shall be the greater
of (x) the fixed rent and additional rent payable by Subtenant as set forth in
the Sublease and (y) the Rent set forth in the Lease. The party to whom
Subtenant attorns shall, under such circumstances, agree not to disturb
Subtenant in its use and enjoyment of the Sublet Space, provided Subtenant
performs all of its obligations under the Lease (except as provided above). Such
party shall not be required to honor or credit Subtenant for (a) any payments of
rent made to Sublandlord for more than one month in advance or for any other
payment owing by, or on deposit with, Sublandlord for the credit of Subtenant,
other than payments actually made to and received by Landlord, (b) any
obligation to perform any work or make any payment to Subtenant pursuant to a
work letter, the Sublease or otherwise, (c) any security deposit not in
Landlord's actual possession, (d) any obligation of, or liability resulting from
any act or omission of, Sublandlord, (e) any amendment of the Sublease not
expressly consented to by Landlord, or (f) any defenses, abatements, reductions,
counterclaims or offsets assertable against Sublandlord. This provision is
self-operative upon demand for attornment, whether or not, as a matter of law,
the Sublease may terminate upon the expiration or termination of the term of the
Lease. Subtenant, however, agrees to give Landlord or such other party, on
request, an instrument acknowledging an attornment according to these terms. No
attornment pursuant to this paragraph shall be deemed a waiver or impairment of
Landlord's rights under the Lease to pursue any remedy not inconsistent with
such attornment. In the event of such election by Landlord or such other party,
Sublandlord shall deliver to Landlord or such other party any security deposit
which Sublandlord is then holding under the Sublease.

     8. Sublandlord and Subtenant each agrees that:

          (a) none of Landlord's shareholders, partners, members, managers,
     directors, officers, agents or employees, directly or indirectly, shall be
     liable for Landlord's performance under the Lease or this Agreement;

          (b) Landlord's liability under the Lease and this Agreement shall be
     limited to Landlord's interest in the Land (as defined in the Lease) and
     the Building (as defined in the Lease);


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          (c) it will not seek to satisfy any judgment against Landlord out of
     the assets of any person or entity other than Landlord (but only to the
     extent provided in clause (b) above); and

          (d) the obligations of Landlord under this Agreement and the Lease
     shall not be binding upon Landlord after the sale, conveyance, assignment
     or transfer by Landlord of its interest in the Land and the Building, and
     Sublandlord and Subtenant shall look solely to the transferee for the
     satisfaction of such obligations. Any such transferee shall be deemed to
     have assumed all of Landlord's obligations under this Agreement and the
     Lease.

     9. Sublandlord and Subtenant, jointly and severally, agree to indemnify
Landlord against, and hold Landlord harmless from, all costs, damages and
expenses, including reasonable attorneys' fees and disbursements, arising out of
any claims for brokerage commissions, finders fees or other compensation by
reason of any person or entity claiming to have dealt with Sublandlord or
Subtenant in connection with the Sublease or procuring possession of the Sublet
Space. Sublandlord and Subtenant, at their sole expense, may defend any such
claim with counsel reasonably acceptable to Landlord and settle any such claim
at their expense, but only Landlord may approve the text of any stipulation,
settlement agreement, consent order, judgment or decree entered into on its
behalf. The provisions of this Paragraph 9 shall survive the expiration or
sooner termination of the Lease or the Sublease.

     10. Sublandlord and Subtenant, jointly and severally, agree to indemnify
Landlord against, and hold it harmless from any and all losses, costs, expenses,
claims and liabilities including, but not limited to, reasonable counsel fees,
arising from any accident, injury or damage whatsoever caused to any person or
entity or to the property of any person or entity and occurring during the term
of the Sublease in or about the Sublet Space, except to the extent caused by the
gross negligence or willful misconduct of Landlord. If any proceeding is brought
against Landlord by reason of any such claim, Sublandlord and Subtenant, jointly
and severally, shall be responsible for Landlord's costs and expenses
(including, without limitation, reasonable attorneys' fees and expenses)
incurred in connection therewith. If any action or proceeding is brought against
Landlord by reason of any such claims, Sublandlord and/or Subtenant, upon
written notice from Landlord, shall, at Sublandlord's and Subtenant's sole cost
and expense, resist or defend such action or proceeding using counsel reasonably
approved by Landlord, but may not settle any such claim without Landlord's prior
written approval. The provisions of this Paragraph 10 shall survive the
expiration or earlier termination of the term of the Sublease or the Lease. The
indemnity and any right granted to Landlord pursuant to this paragraph shall be
in addition to, and not in limitation of, Landlord's rights under the Lease.
Subtenant shall name the Landlord as an additional insured on all liability
insurance policies.

     11. Landlord's consent to the Sublease does not include consent to any
modification, supplement or amendment of the Sublease, or to any assignment of
the Sublease or further subletting of the Sublet Space, each of which requires
Landlord's prior written consent. If Sublandlord or Subtenant desires Landlord's
consent to any such other action it must specifically and separately request
such consent, such consent in the case of Sublandlord shall be granted or denied
pursuant to the terms of the Lease. Sublandlord shall give Landlord prompt
written notice if the Sublease terminates prior to its stated term.

     12. Neither the execution and delivery of this Agreement or the Sublease,
nor any acceptance of rent or other consideration from Subtenant by Landlord or
Landlord's agent


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<PAGE>


shall operate to waive, modify, impair, release or in any manner affect
Sublandlord's liability or obligations under the Lease or Subtenant's liability
or obligations under the Sublease. Sublandlord and Subtenant each agrees that
any additional services requested and authorized by Subtenant are deemed to be
authorized by Sublandlord, and the charges for such additional services that are
assessed by Landlord constitute additional rent payable under the Lease.

     13. If there shall be any conflict or inconsistency between the terms,
covenants and conditions of this Agreement or the Lease and the Sublease, then
the terms, covenants and conditions of this Agreement or the Lease shall
prevail. If there shall be any conflict or inconsistency between this Agreement
and the Lease, then the terms, covenants and conditions of this Agreement shall
prevail.

     14. The Lease and this Agreement constitute the entire agreement of the
parties with respect to Landlord's consent to the Sublease. This Agreement may
not be changed except in writing signed by each party hereto.

     15. All statements, notices and other communications given pursuant to this
Agreement must be in writing and must be delivered as provided in the Lease,
addressed to Landlord and Sublandlord as provided in the Lease and to Subtenant
at its address set forth above or at such other address as any party may
designate upon not less than 10 days prior notice given in accordance with this
paragraph.

     16. Landlord's rights and remedies under this Agreement shall be in
addition to every other right or remedy available to it under the Lease, at law,
in equity or otherwise and Landlord shall be able to assert its rights and
remedies at the same time as, before, or after its assertion of any other right
or remedy to which it is entitled without in any way diminishing such other
rights or remedies. The invalidity or unenforceability of any provision of this
Agreement shall not impair the validity and enforceability of any other
provision of this Agreement.

     17. This Agreement shall bind and inure to the benefit of the parties and
their respective successors and assigns, except as provided in Paragraph 8(d)
above and except that it shall not inure to the benefit of any successor or
assign of Sublandlord or Subtenant whose status was acquired in violation of the
Lease or this Agreement.

     18. Each of Landlord, Sublandlord, and Subtenant represents that it is duly
authorized to execute and deliver this Agreement, and that each of Landlord,
Sublandlord and Subtenant has full power and authority to enter into this
Agreement.

     19. This Agreement will be construed and governed by New York law.
Sublandlord and Subtenant each consents to the personal and subject matter
jurisdiction of the courts of the State of New York.

     20. This Agreement may be executed in counterparts, each of which shall be
deemed an original, and all such counterparts shall together constitute one and
the same instrument.

     21. Sublandlord and Subtenant each agrees jointly and severally to pay,
upon demand, Landlord's reasonable out-of-pocket fees and disbursements incurred
in connection with and related to the preparation and execution of this
Agreement.


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     22. EACH OF THE PARTIES HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ITS
RIGHT TO A JURY TRIAL IN ANY CAUSE OF ACTION ARISING OUT OF, OR RELATING TO,
THIS AGREEMENT.


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     Please acknowledge your agreement to the terms and conditions of this
Agreement by signing the copy of this Agreement enclosed herewith and returning
it to the Landlord. You may consider Landlord's consent to be effective upon
your receipt of a fully executed copy of this Agreement.

                             Very truly yours,



                                  RCPI LANDMARK PROPERTIES, L.L.C., Landlord
                                  By: Tishman Speyer Properties, L.P., its Agent


                                       By: /s/ Burton Lehman
                                           ---------------------------
                                           Name:    BURTON LEHMAN
                                           Title:   VICE PRESIDENT


Agreed and Consented to by:


ANTIGENICS, INC., Sublandlord


By: /s/ P. Thornton
    --------------------------
    Name: P THORNTON
    Title: CFO


OMRIX BIOPHARMACEUTICALS INC., Subtenant


By: /s/ Michael Burshtine
    --------------------------
    Name: MICHAEL BURSHTINE
    Title: CFO


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<PAGE>
                                     EXHIBIT

                                    Sublease

                                  See Attached



<PAGE>


                                    SUBLEASE

      This SUBLEASE is made as of February 2nd, 2006, by and between Antigenics,
Inc., a Delaware corporation having an address at 630 Fifth Avenue, New York,
New York 10111 ("Sublessor") and Omrix Biopharmaceuticals Inc., a Delaware
corporation having an address at 708 Third Avenue, New York, New York 10017
("Sublessee").

                                   WITNESSETH:

      WHEREAS, pursuant to that Lease dated as of December 6, 1995, as amended
by a First Amendment to Lease dated as of October 23, 1996, a Second Amendment
to Lease dated as of February 25, 2000 and a Third Amendment to Lease dated as
of March 23, 2001 by and between RCPI Trust (as successor in interest to
Rockefeller Center Properties), as landlord ("Prime Lessor") and Sublessor (as
successor in interest to GHA Management Corporation as assigned by GHA
Management Corporation to Sublessor pursuant to that certain Assignment of Lease
dated as of January 3, 2000), as tenant (such lease, as so amended, and all
renewals, modifications and extensions thereof are hereinafter collectively
referred to as the "Prime Lease"), a true and complete copy (less certain
redacted information) of which is attached hereto as EXHIBIT A, whereby
Sublessor leases space on floor(s) 21 and 22 located in the building known as
and numbered 630 Fifth Avenue, New York, New York (the "Building") (all as more
particularly described in the Prime Lease the "Premises"); and

      WHEREAS, Sublessee desires to sublease a portion of the Premises from
Sublessor and Sublessor is willing to sublease the same, all on the terms and
conditions hereinafter set forth;

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

      1. Sublease of Subleased Premises. For the rent and upon the terms and
conditions herein, Sublessor hereby subleases to Sublessee, and Sublessee hereby
subleases from Sublessor approximately 2,658 square feet of rentable space
located on the 22nd floor as shown on EXHIBIT B attached hereto (the "Subleased
Premises"). During the term hereof, Sublessee shall have access to the Subleased
Premises twenty-four (24) hours a day, 7 days a week, subject to the terms of
this Sublease. Sublessor also grants Sublessee the right to use, without
additional charge during the term of this Sublease, those items of personal
property located in the Subleased Premises on the date hereof (the "Furniture"),
together with the existing network wiring/equipment (including handsets),
voicemail systems, internet access, security system (including door cards) (the
"Systems") and fixtures in the Subleased Premises as of the Commencement Date.
Sublessor hereby represents and warrants that the Systems are in good working
order. Sublessor agrees to maintain the Systems in working order during the Term
of the Sublease. Sublessor will provide Sublessee with the direct contact
information of a technician or equivalent person who is available during regular
business hours to service the Systems and a contact for after-hours Systems
services. Sublessee's sole remedy in


<PAGE>


the event of a violation of such representation and warranty is for Sublessee to
receive from Sublessor the same level of service to Sublessee as Sublessor
provides itself. Notwithstanding the foregoing, Sublessee shall in no event be
responsible for maintaining or repairing the Systems. Other than as set forth
herein, Sublessee accepts possession of the Furniture, the Systems and fixtures
"as is, where is" and in their current condition, Sublessor having made no
representation or warranty of any kind, express or implied (including, but not
limited to, any warranty of fitness for any particular use or purpose or
security with respect to the voicemail or internet access connections) with
respect to any of the same. Sublessor shall provide Sublessee with open
connections for internet service and computer connections and the use of the
existing security system and telephone system in the Subleased Premises.
Sublessee acknowledges and agrees that it is responsible for securing the
telephone and internet connections and for the security of the Subleased
Premises and any persons therein or thereon. For the avoidance of doubt it is
clarified that Sublessee emails and internet activity will not be recorded or
otherwise accessible by Sublessor. Sublessee releases and indemnifies Sublessor
and its directors, officers, agents and employees from any liability with
respect to the use/security of the telephone and internet connections and the
security of the Subleased Premises and any persons therein or thereon. Sublessor
agrees to allow Sublessee to use, without additional charge, Sublessor's
receptionist services on the 21st floor of the Building. Upon the date on which
this Sublease has been fully executed by Sublessor and Sublessee and the Prime
Lessor has delivered the "Consent" as hereinafter defined, Sublessee shall have
the right to enter the Subleased Premises for the purposes of inspecting the
Subleased Premises, taking measurements and preparing for the move into the
Subleased Premises. Sublessor shall have the right to have a representative
present any time such early entry right is exercised. If Sublessee enters the
Subleased Premises prior to the Commencement Date, Sublessee shall be
responsible for complying with all of the terms of this Sublease and the Prime
Lease to the extent incorporated herein by reference, other than the payment of
Rent.

      2. Term. The Term of this Sublease shall commence upon the later of: (i)
February 15, 2006 and (ii) the date on which this Sublease has been fully
executed by Sublessor and Sublessee and the Prime Lessor has delivered the
"Consent" as hereinafter defined and (iii) the date the "Rent" as hereinafter
defined, is received by Sublessor (the "Commencement Date"), and shall expire at
11:59 p.m. on December 27 2006 (the "Expiration Date") or such earlier date upon
which said term may expire, be canceled or be terminated pursuant to any of the
terms or provisions of the Prime Lease this Sublease or applicable law.
Following the Commencement Date, Sublessor will prepare and execute a written
confirmation indicating the exact date of the Commencement Date. In the event
that the "Consent" is not delivered to the Sublessor by March 1st, 2006 this
agreement may be terminated by either party with no liability to the Sublease or
the Sublessor.

      3. Appurtenant Rights. Sublessee shall have, as appurtenant to the
Subleased Premises, rights to use in common with Sublessor and others entitled
thereto Sublessor's rights in driveways, walkways, hallways, stairways and
passenger elevator convenient for access to the Subleased Premises and the
lavatories nearest thereto as shown on EXHIBIT B attached hereto.


<PAGE>


      4. Rent. Upon receipt of Prime Lessor's consent to the Sublease, and prior
to Sublessee taking possession of the Subleased Premises, provided that Prime
Lessor's consent will be received by Sublessor by February 15th, 2006,
Sublessee shall pay to Sublessor $160,363.64 as rent (the "Rent") for this
Sublease. In the event that Prime Lessor's consent is received after Feb 15th
2006, the Rent will be reduced by $763.64 per business day from February 15th
2006 until the Prime Lessor's consent is received by Sublessor. Sublessor shall
forward such Rent to the Prime Lessor together with any additional rental
amounts owed solely by Sublessor for the Subleased Premises under the Prime
Lease. Sublessor shall provide Sublessee with a copy of the monthly statement
from Prime Lessor in respect of the Subleased Premises. Such statement shall
confirm receipt of such payment in respect of the Subleased Premises. Rent is
intended to be gross rent and includes taxes, operating expenses, ordinary
cleaning services, utilities, and heating and air conditioning (during normal
business hours as set forth in the Prime Lease) due under the Prime Lease. At
all other times, Sublessee may request of Sublessor, and Sublessor shall request
of Prime Lessor, that Sublessee be furnished heat, ventilation and air
conditioning to the Subleased Premises. Sublessee shall pay any charges that
Prime Lessor charges to Sublessor in connection with such service but Sublessor
will not charge any mark-up or fee above any amounts charged by Prime Lessor
pursuant to the Prime Lease for the foregoing after-hours services.

      5. (Intentionally omitted)

      6. Permitted Uses. Sublessee shall use the Subleased Premises only for
general office uses and the uses permitted under the Prime Lease. Sublessee
shall not do, suffer or permit anything to be done in or upon the Subleased
Premises except in accordance with and as permitted by the Prime Lease and
applicable law. Sublessee shall comply with the certificate of occupancy
relating to the Subleased Premises and with all laws, statutes, ordinances,
orders, rules, regulations and requirements of all federal, state and municipal
governments and the appropriate agencies, officers, departments, boards and
commissions thereof, and the board of fire underwriters and/or the fire
insurance rating organization or similar organization performing the same or
similar functions, whether now or hereafter in force, applicable to the
Subleased Premises.

      7. Condition of Subleased Premises. Sublessee represents that it has made
or caused to be made a thorough examination and inspection of the Subleased
Premises and is familiar with the condition of every part thereof. Sublessee
agrees that, except as expressly provided herein, (i) it enters into this
Sublease without relying upon any representations, warranties or promises by
Sublessor, its agents, representatives, employees, servants or any other person
in respect of the Building or the Subleased Premises, (ii) no rights, easements
or licenses are acquired by Sublessee by implication or otherwise except as
expressly set forth herein, (iii) Sublessor shall have no obligation to do any
work in order to make the Subleased Premises suitable and ready for occupancy
and use by Sublessee and (iv) the Subleased Premises are in satisfactory
condition.

<PAGE>


      Sublessee shall make no alterations, installations, removals, additions or
improvements in or to the Subleased Premises or any other portion of the
Building.

      Sublessee shall keep and maintain the Subleased Premises, the Furniture,
the Systems and the fixtures and equipment therein clean and in good order,
repair and condition, except for reasonable wear and tear and damage by fire or
other casualty or condemnation.

      Sublessee acknowledges and agrees that Sublessor shall have the right to
repair and restore the direct access between the 21st and 22nd floors of the
Premises upon reasonable notice to the Sublessee and at commercially reasonable
times following the Commencement Date.

      8. Insurance. Sublessee shall maintain throughout the term of this
Sublease such insurance in respect of the Subleased Premises and the conduct and
operation of business therein, with Sublessor and Prime Lessor listed as
additional insureds as is required of "Tenant" pursuant to the terms of the
Prime Lease (including, without limitation, Section 6.1(k) as hereinafter
incorporated by reference) with no penalty to Sublessor or Prime Lessor
resulting from deductibles or self-insured retentions effected in Sublessee's
insurance coverage, and with such other endorsements and provisions as Sublessor
or Prime Lessor may reasonably request. If Sublessee fails to procure or
maintain such insurance and to pay all premiums and charges therefor within ten
(10) days after notice from Sublessor, Sublessor may (but shall not be obligated
to) do so, whereupon Sublessee shall reimburse Sublessor upon demand. All such
insurance policies shall, to the extent obtainable, contain endorsements
providing that (i) such policies may not be canceled except upon thirty (30)
days' prior notice to Sublessor and Prime Lessor, (ii) no act or omission of
Sublessee shall affect or limit the obligations of the insurer with respect to
any other named or additional insured and (iii) Sublessee shall be solely
responsible for the payment of all premiums under such policies and Sublessor,
notwithstanding that it is or may be a named insured, shall have no obligation
for the payment thereof. Such insurance shall otherwise be reasonably acceptable
to Sublessor in both form and substance. On or before the Commencement Date,
Sublessee shall deliver to Sublessor and Prime Lessor a certificate evidencing
the foregoing coverages. Any endorsements to such certificates shall also be
delivered to Sublessor and Prime Lessor upon issuance thereof. Sublessee shall
procure and pay for renewals of such insurance from time to time before the
expiration thereof, and Sublessee shall deliver to Sublessor and Prime Lessor
such renewal certificates at least thirty (30) days before the expiration of any
existing policy. In the event Sublessee fails so to deliver any such renewal
certificate at least thirty (30) days before the expiration of any existing
policy, Sublessor shall have the right, but not the obligation, to obtain the
same if Sublessee does not provide evidence of the same within fifteen (15) days
of request by Sublessor, where upon Sublessee shall reimburse Sublessor upon
demand. Notwithstanding anything to the contrary contained herein, Sublessee
shall be permitted to maintain insurance with respect to the Subleased Premises
pursuant to an umbrella insurance policy, provided that such umbrella insurance
policy meets the insurance requirements of the Prime Lease.


<PAGE>


      Sublessee shall include in all such insurance policies any clauses or
endorsements in favor of Prime Lessor including, but not limited to, waivers of
the right of subrogation, which Sublessor is required to provide pursuant to the
provisions of the Prime Lease. Sublessee releases and waives all claims against
Sublessor for loss or damage to Sublessee's personal property and its
alterations in the Subleased Premises, except to the extent arising from any
negligence or willful misconduct of Sublessor or any of Sublessor's employees,
agents contractors or invitees.

      9. Indemnification Sublessee agrees to protect, defend (with counsel
reasonably approved by Sublessor), indemnify and hold Sublessor and Prime Lessor
and their respective directors, officers, agents and employees harmless from and
against any and all liability, claims, suits, demands, judgments, costs, losses,
interest and expenses (except to the extent arising from any negligence or
willful misconduct of Prime Lessor or Sublessor or their contractors, invitees,
agents or employees), arising: (i) from the conduct or management of or from any
work or thing whatsoever done in the Subleased Premises during the term hereof;
(ii) from any condition arising, and any injury to or death of persons, damage
to property or other event occurring or resulting from an occurrence in the
Subleased Premises during the term hereof; and (iii) from any breach or default
on the part of Sublessee in the performance of any covenant or agreement on the
part of Sublessee to be performed pursuant to the terms of this Sublease or from
any willful misconduct or negligence on the part of Sublessee or any of its
agents, employees, licensees, invitees or assignees or any person claiming
through or under Sublessee. Sublessee further agrees to indemnify Sublessor and
Prime Lessor and their respective officers, agents and employees from and
against any and all liability, claims, suits, demands, judgments, costs, losses,
interest and expenses (including, without being limited to, reasonable
attorneys' fees and expenses), incurred in connection with any such indemnified
claim or any action or proceeding brought in connection therewith. The
provisions of this Paragraph are intended to supplement any other
indemnification provisions contained in this Sublease and in the Prime Lease to
the extent incorporated by reference herein. Any non-liability, indemnity or
hold harmless provisions in the Prime Lease for the benefit of Prime Lessor that
are incorporated herein by reference shall be deemed to inure to the benefit of
Sublessor and Prime Lessor. The indemnity shall survive the expiration or
earlier termination of this Sublease.

      10. No Assignment or Subletting. Sublessee shall not assign, sell,
mortgage pledge or in any manner transfer this Sublease or any interest herein,
or the term or estate granted hereby or the rentals hereunder, or sublet the
Subleased Premises or any part thereof, or grant any concession or license or
otherwise permit occupancy of all or any part of the Subleased Premises by any
person, without the prior written consent of Sublessor and Prime Lessor. Neither
the consent of Sublessor or Prime Lessor to an assignment, subletting,
concession, or license, nor the references in this Subcase to assignees,
subtenants, concessionaires or licensees, shall in any way be construed to
relieve Sublessee of the requirement of obtaining the consent of Sublessor and
Prime Lessor to any further assignment or subletting or to the making of any
assignment, subletting, concession or license for all or any part of the
Subleased Premises. Notwithstanding any assignment or subletting, including,
without limitation, any assignment or subletting permitted or consented to, the
original Sublessee named herein


<PAGE>


and any other person(s) who at any time was or were Sublessee shall remain fully
liable under this Sublease. If this Sublease is assigned, or if the Subleased
Premises or any part thereof is underlet or occupied by any person or entity
other than Sublessee, Sublessor may, after default by Sublessee, following
notice and the expiration of any cure period, collect rent from the assignee,
undertenant or occupant, and apply the net amount collected to the rents payable
by Sublessee hereunder, but no assignment, underletting, occupancy or collection
shall be deemed a waiver of the provisions hereof, the acceptance of the
assignee, undertenant or occupant as tenant, or a release of Sublessee from the
further performance by Sublessee of the covenants hereunder to be performed on
the part of Sublessee. Any attempted assignment or subletting without the prior
written consent of the Sublessor and the Prime Lessor shall be void.

      11. Primacy and Incorporation of Prime Lease.

      (a) This Sublease is and shall be subject and subordinate to the Prime
Lease and to all matters to which the Prime Lease is or shall be subject and
subordinate, and to all amendments, modifications, renewals and extensions of or
to the Prime Lease and Sublessor purports hereby to convey, and Sublessee takes
hereby, no greater rights then those accorded to or taken by Sublessor as
"Tenant" under the terms of the Prime Lease. To the extent incorporated herein,
Sublessee covenants and agrees that it will perform and observe all of the
provisions contained in the Prime Lease to be performed and observed by the
"Tenant" thereunder as applicable to the Premises, other than the payment of
rent. Notwithstanding the foregoing, Sublessee shall have no obligation to (i)
cure any default of Sublessor under the Prime Lease unless directly and actually
caused by Sublessee's default under this Sublease, (ii) perform any obligation
of Sublessor under the Prime Lease which arose prior to the Commencement Date
and Sublessor failed to perform, (iii) repair any damage to the Premises caused
by Sublessor, (iv) remove any alterations or additions installed within the
Premises prior to the Commencement Date, (v) indemnify Sublessor or Prime Lessor
with respect to any negligence or willful misconduct of Sublessor, its agents,
employees or contractors, or (vi) discharge any liens on the Premises or the
Building which arise out of any work performed, or claimed to be performed, by
or at the direction of Sublessor. Except to the extent inconsistent with the
context hereof, capitalized terms used and not otherwise defined herein shall
have the meanings ascribed to them in the Prime Lease. Further, except as set
forth below, the terms, covenants and conditions of the following specified
provisions of the Prime Lease are incorporated herein by reference as if such
terms, covenants and conditions were stated herein to be the terms, covenants
and conditions of this Sublease, so that except to the extent that they are
inconsistent with or modified by the provisions of this Sublease, for the
purpose of incorporation by reference each and every referenced term, covenant
and condition of the Prime Lease binding upon or inuring to the benefit of the
"Landlord" thereunder shall, in respect of this Sublease and the Subleased
Premises, be binding upon or inure to the benefit of Sublessor, and each and
every referenced term, covenant and condition of the Prime Lease binding upon or
inuring to the benefit of the "Tenant" thereunder shall, in respect of this
Sublease, be binding upon or inure to the benefit of Sublessee, with the same
force and effect as if such terms, covenants and conditions were completely set
forth in this Sublease: Articles/Sections: 1.3, 1.6 (excluding the last
sentence), 1.7 (wherever "Tenant" is


                                       6
<PAGE>


referenced replace with "Sublessor"), 3,4,6,8,11,12,14,15,16,17,18,19,21,23,25
(excluding 25.7 and 25.13), 29, 30 (excluding 30.5), and Exhibit A; Paragraph 3
of the First Amendment to Lease; Paragraph 3 and Exhibit B of the Second
Amendment to Lease; and the second grammatical paragraph of Paragraph 3(a),
Paragraph 3(b) and Exhibit A of the Third Amendment to Lease. Notwithstanding
the foregoing, for purposes of this Sublease, as to such incorporated terms,
covenants and conditions:

      (i)   references in the Prime Lease to the "Premises" shall be deemed to
            refer to the "Subleased Premises" hereunder;

      (ii)  references in the Prime Lease to "Landlord" and to "Tenant" shall be
            deemed to refer to "Sublessor" and "Sublessee" hereunder,
            respectively, except that where the terms "Landlord" is used in the
            context of ownership or management of the entire Building, such term
            shall be deemed to mean "Prime Lessor";

      (iii) references in the Prime Lease to "this Lease" shall be deemed to
            refer to "this Sublease" (except when such reference in the Prime
            Lease is, by its terms (unless modified by this Sublease), a
            reference to any other section of the Prime Lease, in which event
            such reference shall be deemed to refer to the particular section of
            the Prime Lease);

      (iv)  references in the Prime Lease to the "term commencement date" shall
            be deemed to refer to the "Commencement Date" hereunder;

      (v)   references in the Prime Lease to the "fixed rent", "additional rent"
            and "Rent" shall be deemed to refer to the "Rent" as defined
            hereunder

      (vi)  references in the Prime Lease to the "term" shall be deemed to refer
            to the "Term" of this Sublease.

      Notwithstanding the foregoing, the following provisions of the Prime
Lease, Exhibits and Schedules annexed thereto are not incorporated herein by
reference and shall not, except as to definitions set forth therein, have any
applicability to this Sublease: Articles/Sections: 1.1, 1.2, 1.4, 1.5, the last
sentence of 1.6, 2, 5, 7, 9, 10, 13, 20, 22, 24, 25.7, 25.13,26, 27, 28, 30.5,
31,32; the First Amendment to Lease (excluding Paragraph 3); the Second
Amendment to Lease (excluding Paragraph 3 and Exhibit B); and the Third
Amendment to Lease (excluding the second grammatical paragraph of Paragraph
3(a), Paragraph 3(b) and Exhibit A).


<PAGE>


      Where reference is made in the following Sections to "Landlord", the same
shall be deemed to refer only to "Prime Lessor": Articles/Sections: 5, 8.2, 9,
10, 12 and 20.

      Where reference is made in the following Sections to "Landlord", the same
shall be deemed to refer to "Prime Lessor" and "Sublessor": Articles/Sections:
6.1(b), 6.1(c) 6.1(e), 6.1(g), 6.1(j), 8.1, 19, 23 and 25.2.

      (b) Notwithstanding such incorporation by reference, Sublessee
acknowledges that pursuant to the Prime Lease, certain services, repairs,
restorations, equipment and access to and for the Premises and insurance
coverage of the Building are in fact to be provided by Prime Lessor and
Sublessor shall have no obligation during the Term of this Sublease to provide
any such services, repairs, restorations, equipment, access or insurance
coverage. Sublessee agrees to look solely to Prime Lessor for the furnishing of
such services, repairs, restorations, equipment, access and insurance coverage.
Sublessor shall cooperate reasonably with Sublessee in obtaining for Sublessee's
benefit the performance by Prime Lessor of its obligations under the Prime
Lease, but Sublessor shall in no event be liable to Sublessee, nor, except as
otherwise expressly set forth in the casualty or condemnation provisions of the
Prime Lease, shall the obligations of Sublessee hereunder be impaired or the
performance thereof excused because of any failure or delay on Prime Lessor's
part in furnishing such services, repairs, restorations, equipment, access or
insurance coverage.

      (c) Notwithstanding anything to the contrary contained in the Prime Lease,
the time limits (the "Notice Periods") contained in the Prime Lease for the
giving of notices, making of demands or performing of any act, condition or
covenant on the part of the "Tenant" (including any grace periods set forth in
Article 15 of the Prime Lease), thereunder, or for the exercise by the "Tenant",
thereunder of any right, remedy or option, are changed for the purposes of
incorporation herein by reference by shortening the same in each instance by
five (5) days (or by three (3) days if the notice period is ten (10) days or
less), so that in each instance Sublessee shall have five (5) (or three (3), as
applicable) fewer days to observe or perform hereunder than Sublessor has as the
"Tenant" under the Prime Lease; provided, however, that if the Prime Lease
allows a Notice Period of five (5) days or less, then Sublessee shall
nevertheless be allowed the number of days equal to one-half of the number of
days in each Notice Period to give any such notices, make any such demands,
perform any such acts, conditions or covenants or exercise any such rights,
remedies or options; provided, further, that if one half of the number of days
in the Notice Period is not a whole number, Sublessee shall be allowed the
number of days equal to one-half of the number of days in the Notice Period
rounded up to the next whole number.

      (d) Notwithstanding anything to the contrary contained in this Sublease
(including, without limitation, the provisions of the Prime Lease incorporated
herein by reference), Sublessor makes no representations or warranties
whatsoever with respect to the Subleased Premises, this Sublease, the Prime
Lease or any other matter, either express or implied, except as expressly set
forth herein, and except that Sublessor represents and warrants, as of the date
of execution hereof, (i) that it is the holder of the interest of the "Tenant"
under the Prime Lease and said interest is not the subject of any


<PAGE>


lien, assignment, conflicting sublease, or other hypothecation or pledge; (ii)
that the Prime Lease is in full force and effect, unmodified and constitutes the
entire agreement between the Prime Lessor and Sublessor in respect of the
Subleased Premises; (iii) that no notices of default have been served on
Sublessor under the Prime Lease which have not been cured; and (iv) to the best
of Sublessor's knowledge, neither Sublessor nor Prime Lessor is in default under
the Prime Lease.

      12. Certain Services and Rights. Except to the extent otherwise expressly
provided herein, the only services or rights to which the Sublessee is entitled
hereunder, including without limitation rights relating to the repair,
maintenance and restoration of the Subleased Premises, are those services and
rights to which Sublessor is entitled under the Prime Lease. Sublessee
acknowledges and agrees that Sublessor shall have no obligation to furnish any
services whatsoever to Sublessee, any such obligation being that of the Prime
Lessor under the Prime Lease, and that, as set forth in Paragraph 11(b) hereof,
the sole obligation of Sublessor hereunder with respect to such services is to
cooperate reasonably with Sublessee to obtain Prime Lessor's performance.

      13. Compliance with Prime Lease. Sublessee acknowledges that it has been
furnished with a copy of and has reviewed the Prime Lease. Sublessee shall
neither do nor knowingly permit anything to be done which would cause the Prime
Lease to be terminated or forfeited by reason of any right of termination or
forfeiture reserved or vested in Prime Lessor under the Prime Lease, and
Sublessee shall defend, indemnify and hold Sublessor harmless from and against
any and all liability, claims, suits, demands, judgments, costs, losses,
interest and expenses (including, without being limited to, reasonable
attorneys' fees and expenses) of any kind whatsoever by reason of any breach or
default on the part of Sublessee by reason of which the Prime Lease may be
terminated or forfeited. Sublessee covenants and agrees that Sublessee will not
do anything which would constitute a default under the provisions of the Prime
Lease or omit to do anything which Sublessee is obligated to do under the terms
of this Sublease: that would constitute a default under the Prime Lease.

      14. Default. In the event that Sublessee shall default in any of its
obligations hereunder beyond applicable cure periods, including any default of
the nature described in the Prime Lease beyond applicable cure periods,
Sublessor shall have available to it all of the rights and remedies available to
Prime Lessor under the Prime Lease, including without limitation Article 15
thereof as and to the extent incorporated herein by reference, as though
Sublessor were the "Landlord" thereunder and Sublessee the "Tenant" thereunder.
Sublessee further agrees to reimburse Sublessor for all costs and expenses,
including reasonable attorneys' fees, incurred by Sublessor in asserting or
enforcing its rights hereunder against Sublessee or any other party.

      15. Brokerage. Sublessee and Sublessor represent that they have not dealt
with any broker in connection with this Sublease. Each party agrees to indemnify
and hold harmless the other from and against any and liability, claims, suits,
demands, judgments, costs, losses, interest and expenses (including, without
being limited to, reasonable attorneys' fees and expenses) which the indemnified
party may be subject to or suffer by reason of any claim made by any person,
firm or corporation for any
<PAGE>
commission, expense or other compensation as a result of the execution and
delivery of this Sublease, which is based on alleged conversations or
negotiations by said person, firm or corporation with the indemnifying party.

      16. (Intentionally omitted)

      17. Notices. All notices, consents, approvals, demands, bills, statements
and requests which are required or desired to be given by either party to the
other hereunder shall be in writing and shall be governed by Article 14 of the
Prime Lease as incorporated herein by reference, except that the mailing
addresses for Sublessor and Sublessee shall initially be those first set forth
above, and after the Commencement Date, to Sublessee at the Subleased Premises,
with a copy of all default and termination notices to Skadden, Arps, Slate,
Meagher & Flom LLP, 4 Times Square, New York, New York 10036, Attention: Marco
Caffuzzi. Sublessee shall mail a copy of all notices to Sublessor at 3 Forbes
Road, Lexington, MA 02421, attention: general counsel. Communications and
payments to the Prime Lessor shall be given in accordance with, and subject to,
Article 14 of the Prime Lease.

      18. Interpretation. This Sublease shall be construed without regard to any
presumption or other rule requiring construction against the party causing this
Sublease to be drafted. Each covenant, agreement, obligation or other provision
of this Sublease shall be deemed and construed as a separate and independent
covenant of the party bound by, undertaking or making the same, which covenant,
agreement, obligation or other provision shall be construed and interpreted in
the context of the Sublease as a whole. All terms and words used in this
Sublease, regardless of the number or gender in which they are used, shall be
deemed to include any other number and any other gender as the context may
require. The word "person" as used in this Sublease shall mean a natural person
or persons, a partnership, a corporation or any other form of business or legal
association or entity. Terms used herein and not defined shall have the meaning
set forth in the Prime Lease.

      19. Fire or Casualty; Eminent Domain. In the event the Subleased Premises
(or access thereto or systems serving the same) are subjected to a fire or other
casualty or to a taking by eminent domain that interferes with the use and
enjoyment by Sublessee of a material portion of the Subleased Premises,
Sublessee shall be entitled to an equitable adjustment of Rent until tenantable
occupancy is restored. At any time that such interference has not been remedied
and tenantable occupancy restored after ninety (90) days from the date such
interference was first experienced, Sublessee may, by notice to Sublessor,
terminate this Sublease. In the event of any taking of the Subleasee Premises,
Sublessee assigns to Prime Lessor any right Sublessee may have to any damages or
award. Sublessee shall not make claims against Sublessor, Prime Lessor or the
condemning authority for damages.

      20. Signage. Subject to the consent of Prime Lessor as required under the
Prime Lease, if any, Sublessee has the right, at its sale cost and expense, to
install signage consistent with Sublessor's signage and that of any other
subtenants on the Building lobby directory and on the entrance to the Subleased
Premises.

                                       10
<PAGE>
      21. Right to Cure Sublessee's Defaults. If Sublessee shall at any time
fail to make any payment or perform any other obligation of Sublessee hereunder,
then Sublessor shall have the right, but not the obligation, after notice to
Sublessee, or without notice to Sublessee in the case of any emergency, and
without waiving or releasing Sublessee from any obligations of Sublessee
hereunder, to make such payment or perform such other obligation of Sublessee in
such manner and to such extent as Sublessor shall deem necessary, and in
exercising any such right, to pay any incidental costs and expenses, employ
attorneys, and incur and pay reasonable attorneys' fees. Sublessee shall pay to
Sublessor upon demand as additional rent all sums so paid by Sublessor and all
incidental costs and expenses of Sublessor in connection therewith, together
with interest thereon at an annual rate equal to the rate two percent (2%) above
the base rate or prime rate then announced as such by the Wall Street Journal,
or the maximum rate permitted by law. Such interest shall be payable with
respect to the period commencing on the date such expenditures are made by
Sublessor and ending on the date such amounts are repaid by Sublessee. The
provisions of this Paragraph shall survive the Expiration Date or the sooner
termination of this Sublease.

      22. Termination of Prime Lease. If for any reason the term of the Prime
Lease shall terminate prior to the Expiration Date, this Sublease shall
thereupon automatically terminate as to the premises demised under the Prime
Lease and Sublessor shall not be liable to Sublessee by reason thereof;
provided, however, that Sublessor agrees that so long as Sublessee is not in
default hereunder, Sublessor shall not voluntarily surrender the Prime Lease,
except in accordance with rights expressly reserved to Sublessor as "Tenant"
under the Prime Lease, including, without limitation, such rights as are
available under Articles 9 and 10 of the Prime Lease in the event of a taking or
casualty. Notwithstanding the foregoing, if the Prime Lease gives Sublessor any
right to terminate the Prime Lease in the event of the partial or total damage,
destruction, or condemnation of the Subleased Premises or the Building, the
exercise of such right by Sublessor shall not constitute a default or breach
hereunder. Nothing herein shall prevent an assignment of the Prime Lease or the
subleasing of additional space covered by the Prime Lease to any third parties
and in no event shall Sublessor have any liability to Sublessee for any defaults
or termination of the Prime Lease by such other subtenants or defaults under
such other subleases.

Upon the expiration or termination of this Sublease, whether by forfeiture,
lapse of time or otherwise, or upon the termination of Sublessee's right of
possession, Sublessee shall (i) remove and restore any and all signage it may
have installed and such alterations, installations, additions and improvements
as Sublessor may have specified at the time Sublessor consented to the same and
(ii) at once surrender and deliver the Subleased Premises, the Furniture and the
Systems in the condition and repair required by, and in accordance with the
provisions of, this Sublease and the Prime Lease, including without limitation
Section 6.1(h) of the Prime Lease as incorporated herein by reference, including
the Furniture and the Systems which shall be in the same condition as at the
date hereof, reasonable wear and tear excepted. If Sublessee shall fail to
remove any of Sublessee's property from the Subleased Premises, such property
shall be deemed abandoned, and Sublessor is hereby authorized, without liability
to Sublessee for loss or damage thereto, at the sole risk of Sublessee, to (a)
remove and store such property at

                                       11
<PAGE>
Sublessee's expense; (b) retain such property, in which case all right, title
and interest therein shall accrue to Sublessor; or, (c) sell such property and
retain the proceeds from such sale, or otherwise dispose or destroy such
property.

      23. Consents and Approvals. All references in this Sublease to the consent
or approval of Prime Lessor and/or Sublessor shall be deemed to mean the written
consent or approval of Prime Lessor and/or Sublessor, as the case may be, and no
such consent or approval of Prime Lessor and/or Sublessor, as the case may be,
shall be effective for any purpose unless such consent or approval is set forth
in a written instrument executed by Prime Lessor and/or Sublessor, as the case
may be. In all provisions requiring the approval or consent of Sublessor
(whether pursuant to the express terms of this Sublease or the terms of the
Prime Lease incorporated herein), Sublessee shall be required to obtain the
approval or consent of Prime Lessor and then to obtain like approval or consent
of Sublessor. If Sublessor is required or has determined to give its consent or
approval to a matter as to which consent or approval has been requested by
Sublessee, Sublessor shall cooperate reasonably with Sublessee endeavoring to
obtain any required Prime Lessor's consent or approval upon and subject to the
following terms and conditions: (i) Sublessee shall reimburse Sublessor for any
reasonable out-of-pocket costs incurred by Sublessor in connection with seeking
such consent or approval, (ii) Sublessor shall not be required to make any
payments to Prime Lessor or to enter into any agreements or to modify the Prime
Lease, or this Sublease in order to obtain any such consent or approval, (iii)
if Sublessee agrees or is otherwise obligated to make any payments to Sublessor,
or Prime Lessor in connection with such request for such consent or approval,
Sublessee shall have made arrangements satisfactory to Sublessor for such
payments and (iv) Sublessee shall indemnify and hold, Sublessor harmless from
and against all liability, claims, suits, demands, judgments, costs, losses,
interest and expenses (including, without being limited to, reasonable
attorneys' fees and expenses) Sublessor shall suffer or incur in connection with
seeking such consent or approval. Nothing contained in this Article shall be
deemed to require Sublessor to give any consent or approval simply because Prime
Lessor has given such consent or approval and, unless provision to the contrary
is expressly made herein, Sublessor's consent may be withheld at its sole
election. Notwithstanding anything to the contrary contained in this Sublease,
Sublessee shall not be required to reimburse Sublessor or Prime Lessor for any
costs incurred by either of them in connection with seeking the Consent.

      24. No Privity of Estate. Nothing contained in this Sublease shall be
construed to create privity of estate or of contract between Sublessee and Prime
Lessor and Prime Lessor is not obligated to recognize or to provide for the
non-disturbance of the rights of Sublessee hereunder.

      25. No Waiver. The failure of Sublessor to insist in any one or more cases
upon the strict performance or observance of any obligation of Sublessee
hereunder or to exercise any right or option contained herein shall not be
construed as a waiver or relinquishment for the future of any such obligation of
Sublessee or any right or option of Sublessor. Sublessor's receipt and
acceptance of Rent or Sublessor's acceptance of performance of any other
obligation by Sublessee, with knowledge of Sublessee's

                                       12
<PAGE>
breach of any provision of this Sublease, shall not be deemed a waiver of such
breach. No waiver by Sublessor of any term, covenant or condition of this
Sublease shall be deemed to have been made unless expressed in writing and
signed by Sublessor.

      26. Complete Agreement. This Sublease constitutes the entire agreement
between the parties and there are no representations, agreements, arrangements
or understandings, oral or written, between the parties relating to the subject
matter of this Sublease which are not fully expressed in this Sublease. This
Sublease cannot be changed or terminated orally or in any manner other than by a
written agreement executed by both parties. This Sublease shall not be binding
upon either party unless and until it is signed and delivered by and to both
parties. This Sublease may be executed in several counterparts, each of which
shall be deemed an original, and all of such counterparts together shall
constitute one and the same instrument.

      27. Successors and Assigns. The provisions of this Sublease, except as
herein otherwise specifically provided, shall extend to bind and inure to the
benefit of the parties hereto and their respective personal representatives,
heirs, successors and permitted assigns.

      28. Waiver of Jury Trial and Right to Counterclaim. The parties hereto
hereby waive any rights which they may have to trial by jury in any summary
action or other action, proceeding or counterclaim arising out of or in any way
connected with this Sublease, the relationship of Sublessor and Sublessee, the
Subleased Premises and the use and occupancy thereof, and any claim for injury
or damages. Sublessee also hereby waives all right to assert or interpose a
counterclaim in any summary proceeding or other action or proceeding to recover
or obtain possession of the Subleased Premises. The parties hereto hereby waive
any rights which they may have to trial by jury in any summary action or other
action, proceeding or counterclaim arising out of or in any way connected with
this Sublease, the relationship of Sublessor and Sublessee, the Subleased
Premises and the use and occupancy thereof, and any claim for injury or damages.
Sublessee also hereby waives all right to assert or interpose a counterclaim
(other than mandatory or compulsory counterclaims) in any summary proceeding or
other action or proceeding to recover or obtain possession of the Subleased
Premises.

      29. Estoppel Certificates. Sublessee shall, within ten (10) days after
each and every request by Sublessor (but in no event shall Sublessor make such
request more than once per month), execute, acknowledge and deliver to Sublessor
or any party reasonably designated by Sublessor, without cost or expense to
Sublessor, a statement in writing (a) certifying that this Sublease is
unmodified and, to the best knowledge of Sublessee, is in full force and effect
(or if there have been modifications, that the same is in full force and effect
as modified, and stating such modifications); (b) specifying the dates to which
Rent has been paid; (c) stating whether or not, to the best knowledge of
Sublessee, Sublessor is in default in the performance or observance of its
obligations under this Sublease and, if so, specifying each such default; (d)
stating whether or not, to the best knowledge of Sublessee, any event has
occurred which, with the giving of notice or passage of time, or both, would
constitute a default by Sublessor under this Sublease, and, if so, specifying
each such default; (e) stating whether or not, to the best

                                       13
<PAGE>
knowledge of Sublessee, any event has occurred which, with the giving of notice
or passage of time, or both, would constitute a default by Prime Lessor under
the Prime Lease with respect to the Subleased Premises, and, if so, specifying
such event; (f) describing all notices of default submitted by Sublessee to
Sublessor and Prime Lessor with respect to this Sublease, or the Prime Lease
from and after the date hereof; and (g) containing such other information with
respect to the Subleased Premises or this Sublease as Sublessor shall reasonably
request. Sublessee hereby acknowledges and agrees that any such statement
delivered pursuant to this Paragraph may be relied upon by any prospective
assignee, transferee or mortgagee of the leasehold estate of Sublessor under the
Prime Lease. Notwithstanding the foregoing, Sublessee acknowledges and agrees to
deliver the aforementioned statement whenever requested by Prime Lessor.

      30. Consent of Prime Lessor. This Sublease is subject to the approval and
consent of Prime Lessor, which Sublessor agrees to use diligent efforts to
obtain. This Sublease shall not become effective unless and until a written
approval and consent (the "Consent") is executed and delivered by the Prime
Lessor, which Consent shall consent to this Sublease. After the Sublessor
receives the Consent from the Prime Lessor, Sublessor agrees to promptly deliver
a fully-executed original of the Consent to Sublessee. The effectiveness of this
Sublease is subject to and conditional upon the receipt by Sublessor and
Sublessee of the Consent. To the extent that Sublessor has not already done so,
upon execution of this Sublease by Sublessee, Sublessor will promptly apply to
the Prime Lessor for the Consent and Sublessor will promptly inform Sublessee as
to receipt of the Consent (if and when it is received) and deliver to Sublessee
a copy of the same.

      31. Limitation of Liability. No director, officer, shareholder, employee,
adviser or agent of Sublessor shall be personally liable in any manner or to any
extent under or in connection with this Sublease. In no event shall Sublessor or
any of its directors, officers, shareholders, employees, advisers or agents be
responsible for any consequential, indirect or special damages or interruption
or loss of business, income or profits, or claims for constructive eviction, nor
shall Sublessor be liable for loss of or damage to artwork, securities or other
valuables, or for other property not in the nature of ordinary fixtures,
furnishings and equipment used in general administrative office activities.

      32. Holdover. If Sublessee shall fail to surrender and deliver the
Subleased Premises as and when required hereunder, Sublessee shall become a
tenant at sufferance only, subject to all of the terms, covenants and conditions
herein specified, including but not limited to the hold-over rental set forth in
the Prime Lease. Sublessee agrees to protect, defend (with counsel reasonably
approved by Sublessor), indemnify and hold harmless Sublessor and its officers,
directors, agents and employees from and against any and all liability, claims,
suits, demands, judgments, costs, losses, interest and expenses (including,
without being limited to, reasonable attorneys' fees and expenses) that
Sublessor may suffer by reason of any holdover by Sublessee hereunder. The terms
and provisions of this Paragraph 32 shall survive the expiration or earlier
termination of this Sublease.

                                       14
<PAGE>
      33. Recording. Sublessor and Sublessee agree that neither party may record
this Sublease.

      34. Attorney's Fees. If either Sublessor or Sublessee shall bring any
action or legal proceeding for an alleged breach of any provision of this
Sublease, to recover Rent, to terminate this Sublease or otherwise to enforce,
protect or establish any term or covenant of this Sublease, the prevailing party
shall be entitled to recover as a part of such action or proceeding, or in a
separate action brought for that purpose, reasonable, actual and documented
attorneys' fees, court costs, and expert fees as may be fixed by the court.

      35. Confidentiality. Each party hereto agrees that this Sublease,
including a terms and provisions hereof, is confidential, provided each party
may disclose terms on a confidential basis (i) to its agents, attorneys, and
consultants; (ii) to Prime Lessor; (iii) to the extent required by law; and (iv)
in connection with any legal action to enforce the terms of this Sublease.

      36. Governing Law. This Sublease is made under, and shall be construed in
accordance with, the laws of the State of New York.

                            [SIGNATURE PAGE FOLLOWS]




                                       15
<PAGE>
      IN WITNESS WHEREOF, Sublessor and Sublessee have executed this Sublease
as a sealed instrument as of the date first written above.

                                   Antigenics, Inc.,
                                        (Sublessor)


                                   By: /s/ P. Thornton
                                      ---------------------------
                                      Name:  P. Thornton
                                      Title: SVP & CFO


                                   Omrix Biopharmaceuticals Inc.,
                                        (Sublessee)

                                   By: /s/ Michael Burshtine
                                      ---------------------------
                                      Name:  Michael Burshtine
                                      Title: SVP & CFO


Sublease between Antigenics Inc and Omrix - 020206F

                                       16
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                                    EXHIBIT A

                                  PRIME LEASE

                                 [SEE ATTACHED]




                                       17
<PAGE>
                                    EXHIBIT B

                        PLAN SHOWING SUBLEASED PREMISES

                                 [SEE ATTACHED]




                                       18
<PAGE>
                                  (FLOOR PLAN)