Document:

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                                                                   Exhibit 10.62

                        CONFIDENTIAL TREATMENT REQUESTED

                           ASSIGNMENT OF PATENT RIGHTS

         WHEREAS, HYBRIDON, INC., a corporation organized and existing under the
laws of the State of Delaware having a principal place of business at 155
Fortune Blvd. Milford, Massachusetts 01757 (hereinafter called "Assignor") is
the owner of:

See Schedule A

 (hereinafter referred to collectively as "Patent Properties").

         WHEREAS, BOSTON BIOSYSTEMS, INC., a corporation organized under the
laws of the State of Delaware having a principal place of business at 78A
Wiggins Avenue, Bedford, Massachusetts, 01730, (hereinafter called "Assignee"),
is desirous of acquiring the entire right, title and interest for the United
States, its territories, dependencies and possessions and in all countries
foreign to the United States, including the full right to claim for any such
application all benefits and priority rights under an applicable convention, in
and to said patents and patent application (and/or patents that may be granted
therefrom), and any continuations, divisions, reissues or extensions of the
same.

         NOW, TO ALL WHOM IT MAY CONCERN: Be it known that for and in
consideration of the sum of One Dollar ($1.00) and for other good and valuable
consideration, the receipt of all of which is hereby acknowledged, the said
Assignor has sold, assigned, transferred and set over, and does hereby sell,
assign, transfer and set over, unto the said Assignee is successors and assigns,
the entire right, title and interest for the United States, its territories,
dependencies and possessions, in all countries foreign to the United States,
including the full right to claim for any possessions and in all countries
foreign to the United States, including the full right to claim for any such
application all benefits and priority rights under any applicable convention, in
and to said Patent Properties (and/or patents that may be granted therefrom),
and any divisions, continuations, reissues or extensions thereof; the same to be
held and enjoyed by said Assignee its successors and assigns, as fully and
entirely as the same would have been held and enjoyed by said Assignor had this
assignment and sale not been made, together with all claims for damages by
reason of past infringement of said Patent Properties with the right to sue for,
and collect the same for its own use and for the use of its successors, assigns
and other legal representatives.

         And I do hereby authorize and request the Commissioner of Patents and
Trademarks of the United States to issue any Letters Patent of the United
States, resulting from said Patent Properties when granted, to said Assignee.
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         The Assignor hereby further covenants and agrees that, at the request
and expense of the Assignee, its successors, legal representatives and assigns,
but without demanding further consideration therefor, the Assignor will (1)
assist in the prosecution of all applications for Letters Patent as herein
described and any other applications for Letters Patent that may be made; (2)
communicate any and all facts known to him respecting said patents and patent
applications; (3) testify in any legal proceeding involving said patents and
patent applications; (4) execute and acknowledge all lawful papers and legal
instruments; (5) execute all divisional, continuing, reissue and reexamination
applications; (6) make all rightful oaths; and (6) generally do any and every
lawful act deemed necessary to aid and cooperate with the Assignee, its
successors, legal representatives and assigns in perfecting and maintaining the
entire interest conveyed herein and in obtaining and enforcing proper patent or
industrial property protection for the subject matter of said patents and patent
applications in any country, particularly in cases of opposition, interference
and litigation;

         The Assignor also covenants and agrees that the rights and obligations
set forth in this instrument shall be binding upon, and inure to the benefit of,
the Assignor's heirs, legal representatives, successors and assigns;

         The Assignor hereby covenants that it has full right to convey the
interest herein assigned and that it has not executed and will not execute any
agreement in conflict herewith.

         The undersigned hereby grants the firm of McDermott, Will & Emery the
power to insert on this Assignment any further identification that may be
necessary or desirable in order to comply with the rules of the United States
Patent and Trademark Office for recordation of this document.

         The Parties hereby agree that this Assignment may be executed in two or
more counterparts each of which shall be deemed an original but all of which
together shall constitute one and the same instrument.

         In testimony whereof, the Assignor and Assignee hereunto sets their
hands and seals the day and year set opposite their signatures.

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BY ASSIGNOR:

                                                     /s/ Robert G. Andersen
                                                     --------------------------
Date: September 19, 2000                             HYBRIDON, INC.
                                                     155 Fortune Blvd.
                                                     Milford, MA 01757

WITNESSED BY:
/s/ Sean B. Leonard

Date: September 19, 2000

State of Massachusetts              )
                                    )    ss:
County of Suffolk                   )

          This 19th day of September 2000, before me personally came the
above-named Assignor to me personally known as the individual who executed the
foregoing assignment, who acknowledged to me that he executed the same of his
own free will for the purposes therein set forth.

                                        /s/ Shawna Hansen
                                        --------------------------------------
                                        My commission expires:

                                        Shawna J. Grimm Hansen, Notary Public
                                        Commonwealth of Massachusetts
                                        My Commission expires 7/23/2004

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BY ASSIGNEE:

Date:  September 21, 2000                            BOSTON BIOSYSTEMS, INC.
                                                     75A Wiggins Ave.
                                                     Bedford, MA 01730

                                            BY:      /s/ Gregory S. Kurey
                                                     --------------------------
                                            PRINTED: Gregory S. Kurey

WITNESSED BY:

Date:
      -----------------------------

Date:
      -----------------------------

State of Massachusetts     )
                           )    ss:
County of Suffolk          )

          This 21st day of September 2000, before me personally came the
above-named duly authorized representative of Assignee personally known to me as
the individual who executed the foregoing Assignment on behalf of the Assignee,
who acknowledged to me that he had the authority to execute same for the
purposes therein set forth.

                                            /s/
                                            -------------------------------
                                            My commission expires:

                                            August 25, 2006

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This Assignments should preferably be signed before: (1) a Notary Public if
within the U.S.A., (b) a U.S. Counsel if outside the U.S.A.. If neither, then it
should be signed before at least two witness. In all cases any formalities of
execution required by the by-laws of the Assignor Company and the state or
country having jurisdiction over the assignor, must be observed.

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                                   SCHEDULE A

(1)      U.S. Patent No. 5,403,709 entitled METHOD OF SEQUENCING SYNTHETIC
         OLIGNONUCLEOTIDES CONTAINING NON-PHOSPHODIESTER INTERNUCLEOTIDE
         LINKAGES;

(2)      U.S. Patent No. 5,420,265 entitled SEPARATION OF PHOSPHORO-THIOATE
         OLIGONUCLEOTIDES BY CAPILLARY GEL ELECTROPHORESIS;

(3)      U.S. Patent No. 5,525,470 entitled METHOD OF SEQUENCING [SHORT]
         OLIGONUCLEOTIDES;

(4)      U.S. Patent No. 5,554,744 entitled METHOD FOR LOADING SOLID SUPPORTS
         FOR NUCLEIC ACID SYNTHESIS;

(5)      U.S. Patent No. 5,627,277 entitled METHOD FOR ANALYZING OLIGNUCLEOTIDE
         ANALOGS;

(6)      U.S. Patent No. 5,639,875 entitled IMPROVED METHOD FOR H PHOSPHONATE
         SYNTHESIS OF OLIGONUCLEOTIES USING TRIPHOSGENE;

(7)      U.S. Patent No. 5,643,717 entitled ANALYTICAL TECHNIQUE FOR
         OLIGONUCLEOTIDE ANALOGS;

(8)      U.S. Patent No. 5,652,103 entitled METHOD OF SEQUENCING SYNTHETIC
         OLIGONUCLEOTIDES CONTAINING PHOSPHODIESTER INTERNUCLEOTIDE LINKAGES;

(9)      U.S. Patent No. 5,668,268 entitled NOVEL POLYMER SUPPORT FOR NUCLEIC
         ACID SYNTHESIS;

(10)     U.S. Patent No. 5,705,629 entitled IMPROVED METHODS FOR H-PHOSPHONATE
         SYNTHESIS OF MONO- AND OLIGONUCLEOTIDES;

(11)     U.S. Patent No. 5,739,314 entitled NEW METHODS OF SYNTHESIZING 2'-O-
         SUBSTITUTED PYRIMIDINE RIBONUCLEOSIDES;

(12)     U.S. Patent No. 5,807,525 entitled APPARATUS AND PROCESS FOR
         MULTI-STAGE SOLID-PHASE SYNTHESIS OF LONG-CHAINED ORGANIC MOLECULES;

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(13)     U.S. Patent No. 5,808,042 entitled IMPROVED PROCEDURE FOR THE
         DETRITYLATION OF DMT-OLIGONUCLEOTIDES USING "DOWEX" ION EXCHANGE;

(14)     U.S. Patent No. 6,087,491 entitled EXTREMELY HIGH PURITY
         OLIGONUCLEOTIDES AND METHODS OF SYNTHESIZING THEM USING DIMER BLOCKS;

(15)     U.S. Patent No. 6,096,881 entitled NOVEL SULFUR TRANSFER REAGENTS FOR
         OLIGONUCLEOTIDE SYNTHESIS;

(16)     U.S. Patent Application Serial No. ***

(17)     U.S. Patent Application Serial No. ***

(18)     U.S. Patent Application Serial No. ***

(19)     U.S. Patent Application Serial No. ***

(20)     U.S. Patent Application Serial No. ***

(21)     U.S. Patent Application Serial No. ***

(22)     U.S. Patent Application Serial No. ***

(23)     U.S. Patent Application Serial No. ***

* To the extent not abandoned.

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                                                                   Exhibit 10.63

                                                CONFIDENTIAL TREATMENT REQUESTED

                                                                  EXECUTION COPY

                 PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT

                         dated as of September 20, 2000

                                 by and between

                                 HYBRIDON, INC.

                                       and

                             BOSTON BIOSYSTEMS, INC.
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                 PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT

            This PNT MONOMER PATENT LICENSE AND OPTION AGREEMENT (the
"Agreement"), dated as of September 20, 2000 (the "Effective Date"), is entered
into by and between Hybridon, Inc., a Delaware corporation (the "Licensor"),
having a principal place of business located at 155 Fortune Blvd., Milford,
Massachusetts 01757 (hereinafter referred to as "HYBRIDON") and Boston
Biosystems, Inc., a Delaware corporation (the "Licensee"), having a principal
place of business located at 75A Wiggins Avenue, Bedford, Massachusetts 01730
(hereinafter referred to as "BBI"). HYBRIDON and BBI are sometimes referred to
herein individually as a "Party" and collectively as the "Parties", and all
references to "HYBRIDON" and "BBI " shall include their respective Affiliates,
where appropriate under the terms of this Agreement.

                              W I T N E S S E T H:

            WHEREAS, HYBRIDON has entered into that certain Asset Purchase
Agreement dated ______ ("Purchase Agreement") to sell certain assets to BBI, and
HYBRIDON wishes to grant certain intellectual property rights as provided
herein;

            WHEREAS, HYBRIDON owns certain patents ("HYBRIDON Patent(s)") and
patent applications ("HYBRIDON Patent Application(s)") that cover PNT Monomer
technology;

            WHEREAS, BBI desires to obtain a royalty-free, non-exclusive license
under the HYBRIDON Patent Application(s), existing patents and any patents
arising from the HYBRIDON Patent Application(s) for non-commercial use; and an
option to enter into a royalty-bearing, non-exclusive license under existing
patents and any patents arising from the HYBRIDON Patent Application(s) for
commercial use;
 and

            NOW, THEREFORE, in consideration of the foregoing recitals and the
mutual covenants and agreements contained herein, the parties hereto, intending
to be legally bound, do hereby agree as follows:

                                    ARTICLE I

                                   DEFINITIONS

            SECTION 1.01. Definitions. The following terms, when capitalized,
shall have the following meanings (such meanings to be equally applicable to
both the singular and plural forms of the terms defined) as used in this
Agreement:

            "Affiliate(s)" means any person, corporation, partnership, firm,
joint venture or other entity now currently existing or which may be formed in
the future, which directly or indirectly, through one or more intermediaries,
controls, is controlled by, or is under common control with, HYBRIDON, BBI, or
AVECIA HOLDINGS PLC, as the case may be. As used in this definition, "control"
means direct or indirect ownership of an entity, whether through the ownership
of more than 50% of the outstanding voting securities or by contract or
otherwise.

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            "AVECIA HOLDINGS PLC" or "AVECIA HOLDINGS" is a company organized
under the laws of United Kingdom, and its registered office address is PO Box
42, Hexagon House, Blackley, Manchester, M9 8ZS, United Kingdom.

            "Change of Control" of a Party means the occurrence of any of the
following with respect to such Party at any time after the date hereof:

                       (a) any Third Party (other than the Affiliates on the
date hereof) shall have become the beneficial owner of securities representing
more than 50% of the aggregate voting power of the then outstanding voting
securities of such Party; or

                       (b) any sale by such Party of: (i) HYBRIDON; or (ii) all
or substantially all of such Party's pharmaceutical and/or healthcare assets; or
(iii) all or substantially all of such Party's assets other than its
pharmaceutical and/or healthcare assets.

            "Confidential Information" shall have the meaning set forth in
Article III.

            "Control" or "Controlled" shall refer to possession of the ability
to grant a license or sublicense of patent rights, know-how or other intangible
rights as provided for herein without violating the terms of any agreement or
other arrangement with any Third Party.

            "Effective Date" shall have the meaning set forth in the Recitals to
this Agreement.

            "Field" or "Field of Use" means the development, use, and
manufacture, of oligonucleotides and products containing oligonucleotides for
non-commercial purposes.

            "HYBRIDON Patent(s)" shall mean any patent set forth in Exhibit A,
as well as those Patents issuing from the HYBRIDON Patent Application(s)
including any foreign, international or domestic counterpart and issued patents
arising therefrom, as well as any divisional, continuation or
continuation-in-part thereof.

            "HYBRIDON Patent Application(s)" shall mean the Patent applications
set forth in Exhibit A, which are pending in the U. S. Patent and Trademark
Office as of the Effective Date, including any foreign, international or
domestic counterpart patent applications, as well as any divisional,
continuation or continuation-in-part thereof.

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            "Licensed Product(s)" means any oligonucleotides made using PNT
Monomers as described and claimed in the HYBRIDON Patents and the HYBRIDON
Patent Applications.

            "Patent" means United States and foreign patents, applications and
provisional applications for United States and foreign patents, and all
reexaminations, reissues, extensions, term restorations, divisionals,
continuations and continuations-in-part thereof.

            "PNT Monomer(s)" is an abbreviation for a monomer comprising a
pentenoyl group, which is a nucleoside base protective group. The HYBRIDON
Patents and HYBRIDON Patent Applications describing and claiming PNT Monomers
are listed in Exhibit A.

            "Product(s)" means Licensed Product(s).

            "Royalty Bearing Sales" means the amount invoiced by BBI, AVECIA
HOLDINGS' Affiliates for sales of Licensed Product to a Third Party less (i)
discounts, including cash discounts, rebates, chargebacks, and retroactive price
reductions or allowances actually allowed or granted from the billed amount, and
fees paid to distributors (other than a distributor that is an Affiliate of such
Party), (ii) credits or allowances actually granted upon claims, rejections or
returns of such sales of such Product, including recalls, regardless of the
Party requesting such recalls, (iii) freight, postage, shipping and insurance
charges paid for delivery of such Product, to the extent billed, (iv) taxes,
duties or other governmental charges levied on or measured by the billing amount
when included in billing, as adjusted for rebates, chargebacks and refunds, and
(v) provisions for uncollectible accounts determined in accordance with such
Party's normal accounting procedures consistently applied within and across its
pharmaceutical operating units.

            "Technical Information" means all know-how, trade secrets,
inventions, data, technology, and other information now owned or licensed by
HYBRIDON, or hereafter acquired or licensed by HYBRIDON during the term of this
Agreement, in connection with the Licensed Product, including, but not limited
to, (i) medical, chemical and other scientific data; (ii) processes and analytic
methodology used in the development, testing and analysis of the Licensed
Product; and (iii) packaging, manufacturing, advertising and marketing data.

            "Territory" means worldwide.

            "Third Party" or "Third Parties" means any entity other than
HYBRIDON, BBI or AVECIA HOLDINGS, and their respective Affiliates.

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                                   ARTICLE II

                              LICENSE AND ROYALTIES

            SECTION 2.01. Grant. Subject to the terms and conditions of this
Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
non-exclusive, paid up, royalty free, perpetual right and license during the
term of this Agreement to use the subject matter disclosed and claimed in the
HYBRIDON Patent Application(s) to make and have made the Licensed Product within
the Field of Use in the Territory.

            SECTION 2.02. Grant. Subject to the terms and conditions of this
Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
non-exclusive, royalty free, perpetual right and license during the term of this
Agreement to use the subject matter disclosed and claimed in the HYBRIDON
Patent(s) to make and have made the Licensed Product within the Field of Use in
the Territory.

            SECTION 2.03. Know-how License Grant. HYBRIDON grants BBI and AVECIA
HOLDINGS' Affiliates a paid-up, non-exclusive license in the Territory, with a
right to use HYBRIDON know-how solely for the purposes of manufacturing and
having manufactured, using, selling, offering for sale and importing the
Licensed Product in the Territory. BBI or AVECIA HOLDINGS' Affiliates will
reimburse HYBRIDON for all reasonable and customary expenses incurred at BBI's
or AVECIA HOLDINGS' Affiliates' request, including a reasonable consulting
hourly rate for time required of HYBRIDON personnel.

            SECTION 2.04. Option Grant. Subject to the terms and conditions of
this Agreement, HYBRIDON hereby grants to BBI and AVECIA HOLDINGS' Affiliates a
*** option to negotiate a non-exclusive, royalty bearing, perpetual right and
license (the "Option License") during the term of this Agreement to use the
subject matter disclosed and claimed in the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) to make and have made, use, sell, offer for sale and
import any products deriving from the HYBRIDON Patent(s) and HYBRIDON Patent
Application(s) for any purposes within the Territory. Unless otherwise agreed,
the financial terms of the Option License shall include, without limitation, a
royalty amount that is no more than *** of the Royalty Bearing Sales ***

         SECTION 2.05.  ***.

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                                   ARTICLE III

                                 CONFIDENTIALITY

            SECTION 3.01. Confidentiality; Exceptions. Except to the extent
expressly authorized by this Agreement or otherwise agreed in writing, the
Parties agree that, for the term of this Agreement and for five (5) years
thereafter, they shall keep confidential the existence of this Agreement and
shall not publish or otherwise disclose or use for any purpose other than as
provided for in this Agreement any information and materials furnished to it by
the other Party pursuant to this Agreement, or any provisions of this Agreement
that are the subject of an Effective order of the Securities Exchange Commission
granting confidential treatment pursuant to the Securities Act of 1934, as
amended (collectively, "Confidential Information"), except to the extent that it
can be established by the receiving Party that such Confidential Information:

            (a) was already known to the receiving Party as shown by written
record, other than under an obligation of confidentiality, at the time of
disclosure by the other Party;

            (b) was generally available to the public or otherwise part of the
public domain at the time of its disclosure to the receiving Party as shown by
written record;

            (c) became generally available to the public or otherwise part of
the public domain after its disclosure and other than through any act or
omission of the receiving Party in breach of this Agreement; or

            (d) was disclosed to the receiving Party, other than under an
obligation of confidentiality, by a Third Party who had no obligation to the
disclosing Party not to disclose such information to others.

            SECTION 3.02. Authorized Disclosure. Each Party may disclose
Confidential Information hereunder to the extent such disclosure is reasonably
necessary in filing or prosecuting patent applications, prosecuting or defending
litigation, complying with applicable governmental regulations or conducting
pre-clinical or clinical trials, provided that if a Party is required by law or
regulation to make any such disclosures of the other Party's Confidential
Information it will, except where impracticable for necessary disclosures, for
example in the event of medical emergency, give reasonable advance notice to the
other Party of such disclosure requirement and, except to the extent
inappropriate in the case of patent applications, will use its reasonable
efforts to secure confidential treatment of such Confidential Information
required to be disclosed. In addition, and with prior written notice to the
other Party of each Third Party with whom a confidential disclosure agreement is
being entered into, each Party shall be entitled to disclose, under a binder of
confidentiality containing provisions as protective as those of this Article,
Confidential Information to any Third Party for the purpose of carrying out the
purposes of this Agreement. Nothing in this Article shall restrict any Party
from using for any purpose any Confidential Information independently developed
by it during the term

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of this Agreement. BBI and AVECIA HOLDINGS' Affiliates may disclose the
existence, but not the terms, of this Agreement to its customers or potential
customers for the purpose of assuring its customers or potential customers of
the existence of the rights conveyed herein.

            SECTION 3.03. Publicity Review. Subject to the further provisions of
this Section, no Party shall originate any written publicity, news release, or
other announcement or statement relating to this Agreement or to performance
hereunder or the existence of an arrangement between the Parties (collectively,
"Written Disclosure"), without the prior prompt review and written approval of
the other, which approval shall not be unreasonably withheld or delayed.
Notwithstanding the foregoing provisions of this Section, any Party may make any
public Written Disclosure it believes in good faith based upon the advice of
counsel is required by applicable law or any listing or trading agreement
concerning its publicly traded securities, provided that prior to making such
Written Disclosure, the disclosing Party shall provide the other Party with a
copy of the materials proposed to be disclosed and provide the receiving Party
with an opportunity to promptly review the proposed Written Disclosure. To the
extent that the receiving Party reasonably requests that any information in the
materials proposed to be disclosed be deleted, the disclosing Party shall
request confidential treatment of such information pursuant to Rule 406 of the
Securities Act of 1933 or Rule 26b-2 of the Securities Exchange Act of 1934, as
applicable (or any other applicable regulation relating to the confidential
treatment of information), so that there be omitted from the materials that are
publicly filed any information that the receiving Party reasonably requests to
be deleted. The terms of this Agreement may also be disclosed to (i) government
agencies where required by law, or (ii) Third Parties with the prior written
consent of the other Party, which consent shall not be unreasonably withheld or
delayed, so long as such disclosure is made under a binder of confidentiality
and so long as highly sensitive terms and conditions such as financial terms are
extracted from the Agreement or not disclosed upon the request of the other
Party. All Written Disclosures shall be factual and as brief as is reasonable
under the circumstances. Upon request by either Party, the Parties agree to
prepare a mutually agreed press release and question and answer document with
respect to this Agreement. Each Party agrees that all Written Disclosures and
oral statements relating hereto shall be consistent with the answers specified
in such question and answer document.

            SECTION 3.04. Survival. This Article shall survive the termination
or expiration of this Agreement for a period of five (5) years.

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                                   ARTICLE IV

                     INTELLECTUAL PROPERTY AND PATENT RIGHTS

            SECTION 4.01. Notice. Each of the parties shall promptly notify the
other in writing if it: (i) receives any notice or becomes aware of any
information that in any way affects the other party's rights under this
Agreement; or (ii) becomes aware of any actual or suspected infringement,
misappropriation or misuse by a Third Party of the HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) in the Territory and within the Field of Use.

            SECTION 4.02. Assistance. At HYBRIDON's request and HYBRIDON's
expense, BBI and AVECIA HOLDINGS' Affiliates shall take all reasonable steps and
shall provide such materials, cooperation and assistance as may be reasonably
required to assist HYBRIDON in maintaining and enforcing HYBRIDON's right in and
to the Intellectual Property.

            SECTION 4.03. Maintenance Fees. Should HYBRIDON decline to pay any
or all of the required maintenance fees on the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) or otherwise to prosecute or maintain the HYBRIDON
Patent(s) and HYBRIDON Patent Application(s), it shall give BBI or AVECIA
HOLDINGS' Affiliates thirty (30) days notice of its decision, and BBI and AVECIA
HOLDINGS' Affiliates shall have the right (but not the obligation) to pay such
maintenance fees or to prosecute or maintain such HYBRIDON Patent(s) and
HYBRIDON Patent Application(s). If BBI and AVECIA HOLDINGS' Affiliates elects to
pay such maintenance fees, HYBRIDON agrees to assign all right, title and
interest in and to the HYBRIDON Patent(s) and HYBRIDON Patent Application(s) to
BBI and AVECIA HOLDINGS' Affiliates without further consideration.

            SECTION 4.04. Infringement.

            (a) HYBRIDON's Rights to Enforce. HYBRIDON shall have the right (but
not the obligation), in its sole discretion, to take action at its own expense
against actual or suspected infringers of the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) in the Field of Use in the Territory, and any and all
recoveries resulting from such actions by HYBRIDON shall be retained by
HYBRIDON. At HYBRIDON's request, and at HYBRIDON's expense, BBI and AVECIA
HOLDINGS' Affiliates shall take all reasonable steps and shall provide any
materials, cooperation and assistance as may be reasonably required to assist
HYBRIDON in taking action against actual or suspected infringers in the Field of
Use in the Territory. BBI and AVECIA HOLDINGS' Affiliates shall join any such
action as a necessary and indispensable party if so required.

            SECTION 4.05.  Defense and Settlement of Third Party Claims.

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            (a) Defense in the Territory. If a Third Party asserts that a
patent, trademark or other intangible right owned by it is infringed by any
Licensed Product in the Territory, BBI and AVECIA HOLDINGS' Affiliates will be
solely responsible for defending against any such assertions at its cost and
expense.

            (b) Settlement with a Third Party. If BBI and AVECIA HOLDINGS'
Affiliates must defend a Third Party claim with respect to a Licensed Product,
then BBI and AVECIA HOLDINGS' Affiliates shall also have the right to control
settlement of such claim.

                                    ARTICLE V

                    INDEMNIFICATION; LIMITATION OF LIABILITY

            SECTION 5.01. Indemnification by HYBRIDON. HYBRIDON shall defend,
indemnify and hold BBI and its subsidiaries and AVECIA HOLDINGS' Affiliates, and
its and their officers, directors, shareholders, employees and agents harmless
and shall pay all losses, damages, fees, expenses or costs (including reasonable
attorneys' fees) incurred by them based upon any claim or action alleging
HYBRIDON's breach of its obligations, representations, warranties or covenants
hereunder unless BBI's or AVECIA HOLDINGS' Affiliatess negligence caused the
losses, damages, fees, expenses or costs.

            SECTION 5.02. Indemnification by BBI and AVECIA HOLDINGS'
Affiliates. BBI and AVECIA HOLDINGS' Affiliates shall defend, indemnify and hold
HYBRIDON and its officers, directors, shareholders, employees and agents
harmless and shall pay all losses, damages, fees, expenses or costs (including
reasonable attorney's fees) incurred by them based upon any claim or action
alleging BBI's and AVECIA HOLDINGS' Affiliates' breach of its obligations,
representations, warranties or covenants hereunder unless HYBRIDON's negligence
caused the losses, damages, fees, expenses or costs.

            SECTION 5.03 Limitation of Liability. EXCEPT AS SET FORTH IN SECTION
7.03 HEREIN, NEITHER PARTY SHALL BE LIABLE TO THE OTHER PARTY OR ANY THIRD PARTY
FOR ANY SPECIAL, CONSEQUENTIAL, EXEMPLARY OR INCIDENTAL DAMAGES (INCLUDING LOST
OR ANTICIPATED REVENUES OR PROFITS RELATING TO THE SAME), ARISING FROM ANY CLAIM
RELATING TO THIS AGREEMENT, THE HYBRIDON PATENT(S) AND HYBRIDON PATENT
APPLICATION(S) OR ANY IMPROVEMENT, WHETHER SUCH CLAIM IS BASED ON WARRANTY,
CONTRACT, TORT (INCLUDING NEGLIGENCE OR STRICT LIABILITY) OR OTHERWISE, EVEN IF
AN AUTHORIZED REPRESENTATIVE OF SUCH PARTY IS ADVISED OF THE POSSIBILITY OR
LIKELIHOOD OF SAME.

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                                   ARTICLE VI

                               DISPUTE RESOLUTION.

            SECTION 6.01. Disputes. The Parties recognize that disputes as to
certain matters may from time to time arise during the term of this Agreement
which relate to either Party's rights and/or obligations hereunder or
thereunder. It is the intent of the Parties to establish procedures to
facilitate the resolution of disputes arising under this Agreement in an
expedient manner by mutual cooperation and without resort to litigation. To
accomplish this objective, the Parties agree to follow the procedures set forth
in this Article if and when a dispute arises under this Agreement.

            SECTION 6.02. Good Faith. The parties shall negotiate in good faith
to resolve the dispute.

            SECTION 6.03. Personal Meeting. If the dispute remains unresolved,
executives from the interested business units or division of the parties shall
meet in person, at a mutually agreed upon time and place, to negotiate in good
faith to resolve the dispute. If the dispute continues to remain unresolved for
more than sixty (60) days from the date the parties met to negotiate pursuant to
this Section, then either party may pursue other dispute resolution procedures,
including the institution of arbitration as more fully set forth herein.

            SECTION 6.04. Alternative Dispute Resolution. Any dispute
controversy or claim arising out of or relating to the validity, construction,
enforceability or performance of this Agreement, including disputes relating to
an alleged breach or to termination of this Agreement, but excluding (i) any
dispute, controversy or claim arising out of or relating to the validity,
enforceability, or infringement of any HYBRIDON Patent(s) or any BBI and AVECIA
HOLDINGS' Affiliates Patent(s) and (ii) other than disputes which are expressly
prohibited herein from being resolved by this mechanism, shall be settled by
binding Alternative Dispute Resolution ("ADR") in the manner described below:

            (a) If a Party intends to begin an ADR to resolve a dispute, such
Party shall provide written notice (the "ADR Request") to counsel for the other
Party informing such other Party of such intention and the issues to be
resolved. From the date of the ADR Request and until such time as any matter has
been finally settled by ADR, the running of the time periods contained in
SECTION 6.05 as to which a Party must cure a breach of this Agreement shall be
suspended as to the subject matter of the dispute.

            (b) Within fifteen (15) business days after receipt of the ADR
Request, the other Party may, by written notice to counsel for the Party
initiating ADR, add additional issues to be resolved.

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            SECTION 6.05. Arbitration Procedures. An ADR initiated under this
Agreement will proceed in accordance with the Commercial Arbitration Rules of
the American Arbitration Association then in effect, insofar as such rules are
not inconsistent with the provisions expressly set forth in this Agreement,
unless the Parties mutually agree otherwise, and pursuant to the following
procedures:

            (a) Notice of the demand for arbitration will be filed in writing
with the other Party and with the American Arbitration Association. The
arbitration panel shall consist of one (1) arbitrator mutually agreed to by the
Parties and the decision shall be final and binding on the Parties and their
legal successors.

            (b) The arbitrator may, at his discretion, provide for discovery by
the Parties, not to exceed four (4) months from the date of filing of the Notice
of Arbitration.

            (c) Any arbitration hearing shall be conducted in Wilmington,
Delaware. The governing law will be as specified herein. The arbitrator will
have authority to award both legal and equitable relief but not to award
punitive damages.

            (d) All costs and fees of the arbitration, other than each Party's
legal fees and expenses, will be allocated by the arbitrators. Subject to
subsection (c), each Party shall bear its own legal fees and expenses.

            (e) A final written decision by the arbitrator will be rendered not
later than thirty (30) days following the completion of the hearing.

            (f) The ADR proceeding shall be confidential and the arbitrator
shall issue appropriate protective orders to safeguard each Party's confidential
information. Except as required by law, no Party shall make (or instruct the
arbitrator to make) any public announcement with respect to the proceedings or
decision of the arbitrator without prior written consent of each other Party.
The existence of any dispute submitted to ADR, and the award, shall be kept in
confidence by the Parties and the arbitrator, except as required in connection
with the enforcement of such award or as otherwise required by applicable law.

            SECTION 6.06. Survivability. Any duty to arbitrate under this
Agreement shall remain in effect and enforceable after termination of this
Agreement for any reason.

            SECTION 6.07. Jurisdiction. For the purposes of this Article, each
Party agrees to abide by the award rendered in any arbitration, and the Parties
agree to accept the jurisdiction of any court having jurisdiction over the
Parties for the purposes of enforcing awards entered pursuant to this Article
and for enforcing the agreements reflected in this Article.

            SECTION 6.08. Equitable Remedies. Nothing in this Section shall
prevent either party from pursuing a temporary restraining order, injunctive
relief or other

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equitable relief against the other party at any time if the allegedly aggrieved
party believes that a breach or a threatened breach of this Agreement would
cause it irreparable harm provided that the other party is given thirty (30)
days written notice prior to equitable relief being sought.

                                   ARTICLE VII

                         REPRESENTATIONS AND WARRANTIES

            SECTION 7.01. HYBRIDON represents, warrants and covenants that:

            (a) HYBRIDON is a corporation duly organized, existing and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers and authorities herein granted.

            (b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which HYBRIDON is a
party, or HYBRIDON's articles of incorporation or bylaws.

            (c) The issued HYBRIDON Patent(s) and any that may issue from the
HYBRIDON Patent Application(s) are valid and enforceable

            (d) This Agreement has been duly executed and delivered by HYBRIDON
and is a legal, valid, and binding obligation enforceable against HYBRIDON in
accordance with its terms.

            (e) HYBRIDON knows of no fact which does or could materially
adversely affect the rights granted to BBI and AVECIA HOLDINGS' Affiliates
hereunder, except as disclosed herein.

            (f) Right of BBI and AVECIA HOLDINGS' Affiliates to Monitor HYBRIDON
Patent Application(s). HYBRIDON covenants that during the term of this
Agreement, HYBRIDON shall provide BBI and AVECIA HOLDINGS' Affiliates with
copies of all substantive communications to and from patent offices regarding
HYBRIDON Patent(s) and HYBRIDON Patent Application(s) promptly after the receipt
thereof.

            SECTION 7.02. BBI  represents, warrants and covenants that:

            (a) BBI is a corporation duly organized, existing, and in good
standing under the laws of the State of Delaware, with full right, power and
authority to enter into and perform this Agreement and to grant all of the
rights, powers, and authorities herein granted.

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            (b) The execution, delivery, and performance of this Agreement do
not conflict with, violate, or breach any agreement to which BBI is a party, or
BBI's certificate of incorporation or bylaws.

            (c) This Agreement has been duly executed and delivered by BBI, and
is a legal, valid, and binding obligation enforceable against BBI and AVECIA
HOLDINGS' Affiliates in accordance with its terms.

            SECTION 7.03. Effect of Representations, Warranties and Covenants.
The Parties agree that if the representations and warranties made by HYBRIDON
under this Article are not true and accurate, or if the covenants made by
HYBRIDON under this Article are not upheld and complied with, and BBI or AVECIA
HOLDINGS' Affiliates incurs reasonably foreseeable damages, liabilities, costs
or other expenses as a result of such falsity or non- compliance, then HYBRIDON
shall indemnify and hold BBI and AVECIA HOLDINGS' Affiliates harmless from and
against any such reasonably foreseeable damages, liabilities, costs or other
expenses incurred as a result of such falsity or such non-compliance.

                                  ARTICLE VIII

                              TERM AND TERMINATION

            SECTION 8.01. Term. This Agreement shall commence as of the
Effective Date and shall remain in force, unless terminated as provided herein.

            (a) Loss of Patent Rights. The provisions of this Agreement shall
continue in effect until the date on which the last to expire, lapse or be
declared invalid or unenforceable HYBRIDON Patent(s) expires, lapses or is
declared invalid or unenforceable by a court of last resort.

            (b) Insolvency. This Agreement will terminate should such BBI and
AVECIA HOLDINGS' Affiliates file a petition of any type as to its bankruptcy, be
declared bankrupt, become insolvent, make an assignment for the benefit of
creditors, go into liquidation or receivership, or otherwise lose legal control
of its business.

            (c) Breach. Either party may terminate this Agreement by giving
notice in writing to the other party in the event such other party is in
material breach of this Agreement and subject to use of Dispute Resolution
procedure of Article VI such other party has failed to cure such breach within
sixty (30) calendar days of receipt of written notice thereof from such party.

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            (d) Survivability. Termination, relinquishment or expiration of the
Agreement for any reason shall be without prejudice to any rights which shall
have accrued to the benefit of either Party prior to such termination,
relinquishment or expiration, including damages arising from any breach
hereunder. Such termination, relinquishment or expiration shall not relieve
either Party from obligations which are expressly indicated to survive
termination or expiration of the Agreement.

                                   ARTICLE IX

                                   BANKRUPTCY

            SECTION 9.01. HYBRIDON shall maintain all HYBRIDON Patent(s) and
HYBRIDON Patent Application(s) licensed hereunder in accordance with the
provisions of SECTION 4.03. All rights and licenses granted under or pursuant to
this Agreement by HYBRIDON to BBI and AVECIA HOLDINGS' Affiliates are, and shall
otherwise be deemed to be, for purposes of Section 365(n) of the Bankruptcy
Code, licenses of rights to "intellectual property" as defined under Section
101(56) of the Bankruptcy Code. The parties agree that BBI and AVECIA HOLDINGS'
Affiliates, as a licensee of such rights and licenses, shall retain and may
fully exercise all of its rights and elections under the Bankruptcy Code. The
parties further agree that, in the event that any proceeding shall be instituted
by or against HYBRIDON seeking to adjudicate it a bankrupt or insolvent, or
seeking liquidation, winding up, reorganization, arrangement, adjustment,
protection, relief or composition of it or its debts under any law relating to
bankruptcy, insolvency or reorganization or relief of debtors, or seeking an
entry of an order for relief or the appointment of a receiver, trustee or other
similar official for it or any substantial part of its property or it shall take
any action to authorize any of the foregoing actions (each a "Proceeding"), BBI
and AVECIA HOLDINGS' Affiliates shall have the right to retain and enforce its
rights under this Agreement, including but not limited to the following rights:

            (a) the right to continue to use the HYBRIDON Patent(s), HYBRIDON
Patent Application(s), and the Licensed Product and all versions and derivatives
thereof, and all documentation and other supporting material related thereto, in
accordance with the terms and conditions of this Agreement;

            (b) the right to a complete duplicate of (or complete access to, as
appropriate) all HYBRIDON Patent(s) and HYBRIDON Patent Application(s) and all
embodiments of such, and the same, if not already in BBI's or AVECIA HOLDINGS'
Affiliates' possession, shall be promptly delivered to BBI or AVECIA HOLDINGS'
Affiliates (i) upon any such commencement of a Proceeding upon written request
therefor by BBI or AVECIA HOLDINGS' Affiliates, unless HYBRIDON elects to
continue to perform all of its obligations under this Agreement; or (ii) if not
delivered under (i) above, upon the rejection of this Agreement by or on behalf
of HYBRIDON upon written request therefor by BBI and AVECIA HOLDINGS'
Affiliates; and

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            (c) the right to obtain from HYBRIDON all documentation and other
supporting materials related to the HYBRIDON Patent(s), HYBRIDON Patent
Application(s), and the Licensed Product and all versions and derivatives
thereof.

                                    ARTICLE X

                                  MISCELLANEOUS

            SECTION 10.01.  Assignment.

            (a) Either Party may assign any of its rights or obligations under
this Agreement in any country to any of the Affiliates and may delegate its
obligations under this Agreement in any country to any of the Affiliates;

            (b) Neither Party may assign its rights or obligations under this
Agreement to non-Affiliates without the prior written consent of the other
Party, except in connection with a merger or similar reorganization or the sale
of all or substantially all of its assets relating to HYBRIDON Patent(s) and
HYBRIDON Patent Application(s).

            (c) This Agreement shall be binding upon and inure to the benefit of
the successors and permitted assigns of the Parties.

            SECTION 10.02. Retained Rights. Nothing in this Agreement shall
limit in any respect the right of either Party to conduct research and
development and to market products using the HYBRIDON Patent(s) and HYBRIDON
Patent Application(s) other than as herein expressly provided.

            SECTION 10.03. Research and Development Entities. Either Party may
assign its rights and obligations under this Agreement to an entity or entities
(e.g., partnership or corporation) that are specifically formed for financial
purposes and that finance research and development performed by such Party.

            SECTION 10.04. Consents Not Unreasonably Withheld or Delayed.
Whenever provision is made in this Agreement for either Party to secure the
consent or approval of the other, that consent or approval shall not
unreasonably be withheld or delayed.

            SECTION 10.05. Force Majeure. Neither Party shall lose any rights
hereunder or be liable to the other Party for damages or losses on account of
failure of performance by the defaulting Party if the failure is occasioned by
government action, war, fire, explosion, flood, strike, lockout, embargo, act of
God, or any other cause beyond the control of the defaulting Party, provided
that the Party claiming force majeure has extended all reasonable efforts to
avoid or remedy such force majeure and has given the other Party prompt notice
describing such event, the effect thereof and the actions being

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taken to avoid or remedy such force majeure; provided, however, that in no event
shall a Party be required to settle any labor dispute or disturbance.

            SECTION 10.06. Notices. All notices hereunder shall be in writing
and shall be deemed given if delivered personally or by facsimile transmission
(receipt verified), telexed, mailed by registered or certified mail (return
receipt requested), postage prepaid, or sent by express courier service, to the
Parties at the following addresses (or at such other address for a Party as
shall be specified by like notice; provided that notices of a change of address
shall be Effective only upon receipt thereof).

                       (a)  If to HYBRIDON:

                       President
                       HYBRIDON, INC.
                       155 Fortune Blvd.
                       Milford, MA 01757

                       (b)  If to BBI:

                       BOSTON BIOSYSTEMS, INC.
                       75A Wiggins Ave.
                       Bedford, MA 01730

            SECTION 10.07. Waiver. Except as specifically provided for herein,
the waiver from time to time by either of the Parties of any of their rights or
their failure to exercise any remedy shall not operate or be construed as a
continuing waiver of same or any other of such Party's rights or remedies
provided in this Agreement.

            SECTION 10.08. Severability. If any term, covenant or condition of
this Agreement or the application thereof to any Party or circumstances shall,
to any extent or in any country, be held to be invalid or unenforceable, then
(i) the remainder of this Agreement shall not be affected thereby and each term,
covenant or condition of this Agreement shall be valid and be enforced to the
fullest extent permitted by law; and (ii) the Parties hereto covenant and agree
to renegotiate any such term, covenant or application thereof in good faith.

            SECTION 10.09. No Strict Construction; Ambiguities. The language
used in this Agreement shall be deemed to be the language chosen by the parties
hereto to express their mutual intent and no rule of strict construction against
either party shall apply to any term or condition of this Agreement.
Ambiguities, if any, in this Agreement shall not be construed against any Party,
irrespective of which Party may be deemed to have authored the ambiguous
provision.

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            SECTION 10.10. Headings. The Sections and paragraph headings
contained herein are for the purposes of convenience only and are not intended
to define or limit the contents of said Sections or paragraphs.

            SECTION 10.11. Governing Law. This Agreement shall be governed by
and interpreted under the laws of the State of Delaware as applied to contracts
entered into and performed entirely in Delaware by Delaware residents.

            SECTION 10.12. Further Assurances. Each of the parties agrees to
execute and deliver such other documents, including but not limited to, updating
the list of HYBRIDON Patent(s) and HYBRIDON Patent Application(s) set forth in
Exhibit A, and to take all such actions as the other party, its successors,
assigns or other legal representatives may reasonably request to effect the
terms of this Agreement.

            SECTION 10.13. Counterparts. This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

            SECTION 10.14. Entire Agreement; Amendments. This Agreement,
including all Exhibits attached hereto and thereto, and all documents delivered
concurrently herewith and therewith, set forth all the covenants, promises,
agreements, warranties, representations, conditions and understandings between
the Parties hereto and supersede and terminate all prior agreements and
understandings between the Parties. Both Parties acknowledge that in deciding to
enter into the Agreement and to consummate the transaction contemplated thereby
neither has relied upon any statement or representations, written or oral, other
than those explicitly set forth therein.

            SECTION 10.15. Independent Contractors. The status of the Parties
under this Agreement shall be that of independent contractors. Neither Party
shall have the right to enter into any agreements on behalf of the other Party,
nor shall it represent to any person that it has any such right or authority.
Nothing in this Agreement shall be construed as establishing a partnership or
joint venture relationship between the Parties.

            SECTION 10.16. Successors. This Agreement will be binding upon and
inure to the benefit of the parties and their respective successors and assigns
in whole or in part.

            SECTION 10.17. Authority of Signatories. Each person executing this
Agreement individually and personally represents and warrants that he is duly
authorized to execute and deliver the same on behalf of the corporation for
which he is signing and that this Agreement is binding upon the corporation in
accordance with its terms.

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            IN WITNESS WHEREOF, HYBRIDON and BBI have caused this Agreement to
be executed as of the date first written above by their respective officers
thereunto duly authorized.

                           [SIGNATURE PAGES TO FOLLOW]

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                                        HYBRIDON, INC..

                                        By:    /s/ Robert G. Andersen
                                           ------------------------------------

                                        Name:   Robert G. Andersen

                                        Title: Chief Financial Officer

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                                        BOSTON BIOSYSTEMS,  INC.

                                        By:     /s/ Gregory S. Kurey
                                           -----------------------------

                                           Name:  Gregory S. Kurey

                                           Title:  General Counsel

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                                    EXHIBIT A

            HYBRIDON PNT MONOMER PATENT(S) AND PATENT APPLICATION(S)

U.S. Patent(s)
         5,614,622
         5,955,599
         5,962,674

U.S. Patent Application(s)
***

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