Exhibit 10.39  [NOTE:
CERTAIN PORTIONS OF THIS DOCUMENT HAVE BEEN MARKED TO INDICATE THAT
CONFIDENTIAL TREATMENT HAS BEEN REQUESTED FOR SUCH PORTIONS BY IMCLONE SYSTEMS
INCORPORATED.  THESE PORTIONS HAVE BEEN
MARKED WITH TWO ASTERISKS ENCLOSED IN BRACKETS (i.e., [**]).  THE CONFIDENTIAL PORTIONS HAVE BEEN OMITTED
AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.]  [IMCLONE LETTERHEAD]  October 12,
2007 Merck KGaA Dr. Wolfgang Wein Frankfurter Strasse 250 64293 Darmstadt Germany  RE:Amended and Restated Co-Development and
Co-Commercialization Agreement for Erbitux in Japan (the Japan Agreement)  Dear Dr. Wein:  This letter agreement (this Agreement)
is intended to clarify the rights and responsibilities of Merck KGaA, a German
corporation with general partners (Merck),Merck Serono Japan
Company, Limited, a Japanese
corporation (MJ), and ImClone Systems Incorporated, a Delaware
corporation (ImClone), under the Japan Agreement and under that
certain Development and License Agreement, dated December 14, 1998,
between Merck and ImClone (as such agreement has been amended, modified and
supplemented, the Existing Agreement) with respect to Japan in light
of their entry into the Japan Agreement. 
This Agreement shall become effective upon the signing of the Japan
Agreement by all of the parties thereto (the Effective Date).  Unless otherwise indicated, initially
capitalized terms shall have the meanings given to them in the Japan Agreement.  1.Royalties for Japan; Other Matters under Japan Agreement.  (a)Royalties.  Except as otherwise provided in Section 1(c) hereof,
following the Effective Date until the expiration of the Japan Agreement or the
termination of Merck or MJ under Article 14 of the Japan Agreement, in
lieu or the royalties required to be paid by Merck to ImClone under the
Existing Agreement in respect of sales in Japan, Merck shall pay, or cause MJ
to pay, to ImClone a royalty equal to 4.75% of Net Sales.  Such royalty shall be paid on a quarterly
basis and at the same time as Merck is required to pay royalties to ImClone under
the Existing Agreement.  Confidential treatment has been requested by ImClone Systems
Incorporated for certain portions of this document.


(b)Adjustments upon Termination of BMS/BMKK as a Party to
the Japan Agreement.  If BMS/BMKK is terminated as a party to the
Japan Agreement prior to termination of this Agreement, then (i) Section 1(a) hereof
will not apply following such termination of BMS/BMKK as a party to the Japan
Agreement, and (ii) ImClone, Merck and MJ shall give effect to the
following provisions (the Post-BMS Termination Adjustments) under the
Japan Agreement and not to any contrary provisions thereof following such
termination of BMS/BMKK:  (A)Profit Or Loss shall be shared as follows[**];  (B)Merck and MJ will provide all of the sales force detailing, marketing,
and promotional effort for Final Product in Japan, and will use Diligent
Efforts to provide such efforts and support as required by, and in accordance
with, those Approved Commercialization Plans then agreed upon as of such
termination date; provided, that Merck and MJ shall have a reasonable
time (not to exceed six months without good cause) in which to ramp up Sales
Force personnel and other internal FTE requirements following such termination
in order to perform the assumed Commercialization obligations of BMS/BMKK;  (C)Commercialization Costs shall be deemed to include the costs of time
spent by employees of ImClone, Merck and MJ on the Commercialization of Final
Product in Japan on an equal FTE Cost basis, and Development Costs shall be
deemed to include the costs of time spent by employees of ImClone, Merck and MJ
on the Development of Final Product in Japan on a basis comparable to such
treatment of Commercialization Costs;  (D)Merck, MJ and ImClone shall use the Long-Term Development Plan and the
Annual Development Plan and Budget and update them as appropriate to reflect
the termination of BMS/BMKK and other relevant circumstances, and will share
the Development effort and the Development Costs thereunder as follows [**]  (E)Merck/MJ and ImClone shall share all Losses arising under Section 13.2
of the Japan Agreement that otherwise would be allocated among the Parties
according to percentages set forth therein as follows[**]  (F)the SCJ will be eliminated and the Steering Committee (as defined in the
Existing Agreement) will serve as the SCJ under the Japan Agreement;  (G)each of the Subcommittees will consist of five members, with three
members designated by Merck and two designated by ImClone, the JJCC will act by
majority vote with each member having one vote and the other Subcommittees will
act by unanimous vote; provided, however, thatin the event that unanimity
cannot be achieved within 20 Business Days after a matter is first submitted to
the JJDC, then the representatives to the JJDC designated by Merck will decide
such matter; provided, further, that in the event that unanimity
cannot be achieved within 20 Business Days after a matter is first submitted to
the JJMC, the  Confidential treatment has been requested by ImClone Systems
Incorporated for certain portions of this document.  2


representatives of the
Party that is responsible for the applicable manufacturing activities will
decide such matter; and  (H)the Alliance Managers will mean the Alliance Managers designated by
Merck/MJ and ImClone.  2.Termination; Effect of Termination.  (a)Termination.  This Agreement shall continue until (i) the
Japan Agreement expires as provided in Section 14.1(a) thereof; (ii) any
of Merck, MJ or ImClone is terminated as a party to the Japan Agreement
pursuant to Section 14.2(b), 14.3, 14.4 or 14.5 thereof; (iii) BMS/BMKK
is terminated as a party to the Japan Agreement and Merck and ImClone
have entered into a New Agreement (as defined below).  (b)Survival.  Sections 2 and 3 hereof shall survive any
termination of this Agreement.  The
rights that have accrued to the benefit of any party hereto prior to any
termination of this Agreement, including, without limitation, the rights of
ImClone to payments from Merck under Section 1(a) hereof with respect
to the period prior to such termination, shall survive any termination of this
Agreement.  (c)Effect of Termination.  Upon termination of this Agreement pursuant
to Sections 2(a)(i) or (ii) hereof, the rights and obligations of
Merck and ImClone to one another with respect to Japan following such
termination shall be governed by the terms and conditions of the Existing Agreement,
except for the rights and obligations under this Agreement that survive such
termination or the Japan Agreement that survive the events that provided the
basis for such termination.  Upon
termination of this Agreement pursuant to Section 2(a)(iii) hereof,
the rights and obligations of Merck and ImClone to one another with respect to
Japan following such termination shall be governed by the terms and conditions
of the New Agreement, except for the rights and obligations under this
Agreement that survive such termination.  (d)New Agreement.  If BMS/BMKK is terminated as a party to the
Japan Agreement, then Merck and ImClone shall promptly begin good faith
negotiations (with a view to finalizing within six months thereafter) to enter
into a new agreement with respect to Japan that will replace and supersede the
Japan Agreement and this Agreement (New Agreement), with the
understanding that the framework for such New Agreement will be the Japan
Agreement as in effect following the termination of BMS/BMKK, except as required
to give effect to the Post-BMS Termination Adjustments.  3.Miscellaneous.  (a)Relationship of Parties.  Nothing in this Agreement is intended or
shall be deemed to constitute a partnership, agency, employer employee or joint
venture relationship among the parties hereto.  Confidential treatment has been requested by ImClone Systems
Incorporated for certain portions of this document.  3


(b)Assignment.  The ability
of each of the parties hereto to assign its rights and obligations under this
Agreement shall be governed by the terms of the Japan Agreement.  Merck and MJ hereby consent to any assignment
by ImClone of the Japan Agreement and this Agreement to an entity that is an
Affiliate of ImClone, it being understood that (a) ImClone will remain
responsible (jointly and severally) with such Affiliate for the performance of
such assigned obligations, and (b) ImClone will cause such assignment and
delegation to terminate if such entity ceases to be an Affiliate of
ImClone.  All of the terms and provisions
of this Agreement shall be binding upon, inure to the benefit of and be
enforceable by the parties hereto and their respective permitted successors and
assigns  (c)Notices.  Any notice or
request required or permitted to be given under or in connection with this
Agreement shall be provided in the manner specified in the Existing Agreement (except
that notices to MJ may be provided to Merck as agent for MJ) and the
effectiveness of such notices shall be governed by the terms thereof.  (d)Amendment
and Waiver.  No amendment, modification or supplement of
any provisions of this Agreement shall be valid or effective unless made in
writing and signed by a duly authorized officer of each of the parties
hereto.  No waiver of any term or
condition of this Agreement shall be valid or effective unless in writing and
signed by the party hereto against which such waiver is sought to be
enforced.  A waiver by any of the parties
hereto of any of the terms and conditions of this Agreement in any instance
shall not be deemed or construed to be a waiver of such term or condition for
the future, or of any subsequent breach hereof.  (e)Severability.  When
possible, each provision of this Agreement will be interpreted in such manner
as to be effective and valid under applicable law, but if any provision of this
Agreement is held to be prohibited by or invalid under applicable law, such
provision will be ineffective only to the extent of such prohibition or invalidity,
without invalidating the remainder of this Agreement.  (f)Governing
Law.  This Agreement shall be governed by and
interpreted in accordance with the laws of the United States and the State of
New York without regard to conflict of law principles.  (g)Disputes.  Except as
otherwise provided in this Agreement, any disputes under this Agreement shall
be addressed in the manner set forth in the Existing Agreement.  (h)Entire
Agreement.  This Agreement, together with the Japan
Agreement and the Existing Agreement, and all exhibits, schedules or amendments
attached thereto, set forth the entire agreement and understanding between the
parties hereto as to the subject matter hereof and merges all prior discussions
and negotiations among them.  This Agreement
is intended to supplement and modify the Existing Agreement with respect to
Japan only, and this Agreement is not intended to and shall not in any way
change or amend any other provisions of the Existing Agreement applicable to
other countries.  Confidential treatment has been requested by ImClone Systems
Incorporated for certain portions of this document.  4


(i)Headings.  The descriptive headings of this Agreement
are for convenience only, and shall be of no force or effect in construing or
interpreting any of the provisions of this Agreement.  (j)Counterparts.  This Agreement may be executed in any number
of identical counterparts, any one of which need not contain the signature of
more than one party hereto, but all such counterparts taken together shall
constitute one and the same agreement.  ***  Please sign in the space provided below to
indicate your agreement to the foregoing. Upon signing of this Agreement by all
of the parties hereto, each of such parties shall be legally bound.  IMCLONE SYSTEMS INCORPORATEDBy:Name:Title:ACKNOWLEDGED AND AGREEDAS OF OCTOBER 12, 2007 BY:MERCK KGAABy:Name:Title:MERCK SERONO JAPAN COMPANY, LIMITEDBy:Name:Title:  Confidential treatment has
been requested by ImClone Systems Incorporated for certain portions of this
document.  5