Document:

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                                                        EXHIBIT 10.90 - ORIGINAL

                              EMPLOYMENT AGREEMENT

        AGREEMENT, dated as of February 1, 2002 by and between ImClone Systems
Incorporated, a Delaware corporation (the "Company") and Clifford R. Saffron
("Executive").

        IN CONSIDERATION of the premises and the mutual covenants set forth
below, the parties hereby agree as follows:

        1.      Employment. The Company hereby agrees to employ Executive as a
Vice-President and Special General Counsel ("SGC") and Executive
hereby accepts such employment, on the terms and conditions hereinafter set
forth.

        2.      Term. The period of employment of Executive by the Company under
this Agreement (the "Employment Period") shall commence on the date hereof (the
"Commencement Date") and shall continue through the first anniversary thereof.
The Employment Period may be sooner terminated by either party in accordance
with Section 6 of this Agreement.

        3.      Position and Duties. During the Employment Period, Executive
shall serve as SGC, and shall report to the Company's Chief Executive Officer.
Executive shall have those powers and duties normally associated with the
position of SGC and shall have such other powers and duties as are assigned to
him by the Company. Executive shall devote all of his working time, attention
and energies during normal business hours (other than absences due to illness or
vacation) to performing his duties for the Company.

        4.      Place of Performance. The principal place of employment of
Executive shall be at the Company's principal executive offices in New York, New
York; provided, that, he may be required to travel on Company business from time
to time.

        5.      Compensation and Related Matters.

                (a)     Base Salary and Bonus. During the Employment Period, the
Company shall pay Executive a base salary at the rate of $225,000 per year
("Base Salary"). Executive's Base Salary shall be paid in approximately equal
installments in accordance with the Company's customary payroll practices. In
addition to Base Salary, Executive shall be eligible to receive an annual target
bonus of $100,000 upon attaining performance goals established by the Company.

                (b)     Stock Options.

                        (i)     The Board of Directors of the Company has
approved a stock option grant to Executive to acquire 60,000 shares of the
Company's common stock (each, an "Option" and collectively the "Options") at a
price of $ 18.44 per share under such terms and conditions as provided for under
the Company's then existing stock option plans which are not inconsistent with
clause (ii) below.
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                        (ii)    The Options described in paragraph (i) above
shall be granted subject to the following terms and conditions: (A) except as
provided below, the Options shall be granted under and subject to the Company's
stock option plan; (B) the exercise price per share of each Option shall be $
18.44, which was the closing price of the Company's common stock on the NASDAQ
(or such other principal trading market for the Company's common stock) on
February 15, 2002, the date that this grant was approved by the Board; (C) the
Options shall be vested and exercisable as to 25% of the shares subject thereto
on the date of grant and as to an additional 25% of the shares subject thereto
on each of the first, second and third anniversaries of the date of grant;
provided, that, Executive is then employed; (D) each Option shall be exercisable
for the ten (10) year period following the date of grant; provided, that,
Executive is then employed; and (E) each Option shall be evidenced by, and
subject to, a stock option agreement whose terms and conditions are consistent
with the terms of employees of the Company who are at a vice president level.

                (c)     Expenses. The Company shall promptly reimburse Executive
for all reasonable business expenses upon the presentation of reasonably
itemized statements of such expenses in accordance with the Company's policies
and procedures now in force or as such policies and procedures may be modified
from time to time.

                (d)     Vacation. Executive shall be entitled to the number of
weeks of paid vacation per year as are customarily provided for an employee of
his position under the Company's vacation policy.

                (e)     Services Furnished. During the Employment Period, the
Company shall furnish Executive with office space, stenographic and secretarial
assistance and such other facilities and services as provided to other employees
of his position.

                (f)     Welfare, Pension and Incentive Benefit Plans and
Perquisites. During the Employment Period, Executive shall be entitled to
participate in such employee benefit plans and insurance programs offered by the
Company, or which it may adopt from time to time, for its employees, in
accordance with the eligibility requirements for participation therein.

                (g)     Signing Bonus. By no later than March 22, 2002, the
Company shall pay Executive a signing bonus of $25,000.

        6.      Termination. Executive's employment hereunder may be terminated
during the Employment Period under the following circumstances:

                (a)     Expiration. The expiration of the Employment Period.

                (b)     Death. The death of Executive.

                (c)     Disability. If, as a result of Executive's physical or
mental incapacity ("Disability"), Executive shall have been substantially unable
to perform his duties hereunder for a period of thirty (30) days in any one-year
period, the Company shall have the right to terminate Executive's employment for
Disability.

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                (d)     Cause. The Company terminates Executive for Cause. For
purposes of this Agreement, the Company shall have "Cause" to terminate
Executive's employment upon Executive's (i) conviction of, or plea of guilty or
nolo contendere to, a felony or any other crime involving moral turpitude; (ii)
breach of any term of this Agreement; (iii) misconduct that is injurious to the
Company; (iv) habitual drug or alcohol abuse; (v) failure to satisfactorily
perform his duties hereunder; or (vi) breach of any Company policy or code of
conduct.

                (e)     Without Cause. The Company terminates Executive's
employment hereunder without Cause by providing Executive with a Notice of
Termination.

                (f)     Resignation by Executive. Executive terminates this
Agreement and Executive's employment hereunder at any time upon thirty (30) days
prior written notice to the Company.

        7.      Termination Procedure.

                (a)     Notice of Termination. Any termination of Executive by
the Company or by Executive (other than termination pursuant to Section 6(a) or
(b) hereof) shall be communicated by written Notice of Termination to the other
party hereto in accordance with Section 12 of this Agreement. For purposes of
this Agreement, a "Notice of Termination" shall mean a notice which shall
indicate the specific termination provision in this Agreement relied upon and
shall set forth in reasonable detail the facts and circumstances claimed to
provide a basis for termination of Executive under the provisions so indicated.

                (b)     Date of Termination. "Date of Termination" shall mean
(i) if Executive's employment is terminated by the expiration of this Agreement,
the date of expiration, (ii) if Executive's employment is terminated by his
death, the date of his death, (iii) if Executive's employment is terminated
pursuant to Section 6(c) hereof, the date the Notice of Termination is given, or
(iv) if Executive's employment is terminated pursuant to any other Section, the
date specified in the Notice of Termination.

        8.      Compensation Upon Termination or During Disability. In the event
Executive is disabled or his employment terminates during the Employment Period,
the Company shall provide Executive with the payments set forth below. Executive
acknowledges and agrees that the payments set forth in this Section 8 constitute
liquidated damages for termination of his employment during the Employment
Period and that prior to receiving any such payments and as a material condition
thereof, Executive shall sign and agree to be bound by a general release of
claims against the Company and any entity in control of, controlled by or under
common control with the Company (an "Affiliate") in such form as is reasonably
satisfactory to the Company.

                (a)     If Executive is terminated pursuant to Sections 6(a),
6(b), 6(c) 6(d), or 6(f), the Company shall pay Executive his accrued, but
unpaid Base Salary and, to the extent permitted by the Company's vacation
policy, his accrued vacation pay, through the Date of Termination (the "Accrued
Benefits"), and the Company shall have no further obligations to Executive under
this Agreement; provided, that, Executive shall also be entitled to any other

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benefit or payment provided pursuant to any plan or policy of the Company in
accordance with such plan's or policy's terms.

                (b)     If Executive's employment is terminated pursuant to
Section 6(e), Executive shall be entitled to (i) payment of his Accrued Benefits
and (ii) the Company shall continue to pay Executive his Base Salary until the
remainder of the Employment Period as though the termination under Section 6(e)
had not occurred; provided, that, such period shall not be less than three (3)
months. The Company shall have no further obligations to Executive under this
Agreement; provided, that, Executive shall also be entitled to any other benefit
or payment provided pursuant to any plan or policy of the Company in accordance
with such plan's or policy's terms.

        9.      Restrictive Covenants.

                (a)     Except (i) as required in order to perform his
obligations under this Agreement, or (ii) as may otherwise be required by law or
any legal process (in which case Executive shall use his reasonable best efforts
in cooperating with the Company in obtaining a protective order against
disclosure by a court of competent jurisdiction), Executive shall not, without
the express prior written consent of the Company, disclose or divulge to any
other person or entity, or use or modify for use, directly or indirectly, in any
way, for any person or entity any of the Company's or any Affiliate's
Confidential Information at any time (during or after Executive's employment).
For purposes of this Agreement, "Confidential Information" of the Company shall
mean any valuable, competitively sensitive data and information related to the
Company's or any Affiliate's business including, without limitation Trade
Secrets (as defined below) that are not generally known by or readily available
to the Company's or any Affiliate's competitors other than as a result of an
improper disclosure directly or indirectly by Executive. "Trade Secrets" shall
mean information or data of the Company or any Affiliate's including, but not
limited to, technical or non-technical data, financial information, programs,
devices, methods, techniques, drawings, processes, financial plans, product
plans, or lists of actual or potential customers or suppliers, that: (A) derive
economic value, actual or potential, from not being generally known to, and not
being readily ascertainable by proper means by, other persons who can obtain
economic value from their disclosure or use; and (B) are the subject of efforts
that are reasonable under the circumstances to maintain their secrecy

                (b)     All records, files, drawings, documents, models,
equipment, and the like containing Confidential Information or needed in the
Company's business which Executive has control over shall not be removed from
the Company's premises without its written consent, unless such removal is in
the furtherance of the Company's business or is in connection with Executive's
carrying out his duties under this Agreement and, if so removed, shall be
returned to the Company promptly after termination of Executive's employment
hereunder, or otherwise promptly after removal if such removal occurs following
termination of employment. The Company shall be the owner of all Trade Secrets
and other products relating to the Company's business developed by Executive
alone or in conjunction with others as part of his employment with the Company.

                (c)     In the scope of Executive's employment with the Company,
he may be requested, alone or with others, to create, invent, enhance, and
modify items which are or

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could be deemed to be Confidential Information. Executive acknowledges and
agrees that all of such information is intended to be, and will remain, the sole
and exclusive property of the Company. In addition, Executive agrees that any
and all intellectual property that Executive invents, discovers, originates,
makes, conceives, creates or authors either solely or jointly with others and
that is the result of or is substantially derived from Confidential Information
shall be the sole and exclusive property of the Company unless in the public
domain. If Executive's employment with the Company terminates for any reason, he
shall promptly and fully disclose all such property to the Company, shall
provide the Company with any information that it may reasonably request about
such property and shall execute such agreements, assignments or other
instruments as may be reasonably requested by the Company to reflect such
ownership by the Company and shall fully cooperate with the Company to protect
the business relationships of the Company and to insure that there will be no
unreasonable interference or disruption of such business relationships.

                (d)     Should Executive engage in or perform any of the acts
prohibited by this Section 9, it is agreed that the Company shall be entitled to
full injunctive relief, to be issued by any competent court of equity, enjoining
and restraining Executive and each and every other person, firm, organization,
association, or corporation concerned therein, from the continuance of such
violative acts. The foregoing remedy available to Company shall not be deemed to
limit or prevent the exercise by the Company of any or all further rights and
remedies which may be available to the Company hereunder or at law or in equity.

        10.     Arbitration. Except as provided for in Section 9 of this
Agreement, if any contest or dispute arises between the parties with respect to
this Agreement, such contest or dispute shall be submitted to binding
arbitration for resolution in New York, New York in accordance with the rules
and procedures of the Employment Dispute Resolution Rules of the American
Arbitration Association then in effect. The decision of the arbitrator shall be
final and binding on both parties, and any court of competent jurisdiction may
enter judgment upon the award. Each party shall pay its own expenses, including
legal fees, in such dispute and shall split the cost of the arbitrator and the
arbitration proceedings.

        11.     Successors; Binding Agreement. The rights and benefits of
Executive hereunder shall not be assignable, whether by voluntary or involuntary
assignment or transfer by Executive. This Agreement shall be binding upon, and
inure to the benefit of, the successors and assigns of the Company, and the
heirs, executors and administrators of the Executive, and shall be assignable by
the Company to any entity acquiring substantially all of the assets of the
Company, whether by merger, consolidation, sale of assets or similar
transactions.

        12.     Notice. For the purposes of this Agreement, notices, demands and
all other communications provided for in this Agreement shall be in writing and
shall be deemed to have been duly given when delivered either personally or by
United States certified or registered mail, return receipt requested, postage
prepaid, addressed as follows:

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                  If to Executive:

                  Clifford Saffron
                  120 Redwood Drive
                  Roslyn, New York 11576

                  If to the Company:

                  ImClone Systems Incorporated
                  180 Varick Street
                  New York, New York  10014
                  Attention:  Chief Financial Officer

or to such other address as any party may have furnished to the others in
writing in accordance herewith, except that notices of change of address shall
be effective only upon receipt.

        13.     Miscellaneous. No provisions of this Agreement may be amended,
modified, or waived unless such amendment or modification is agreed to in
writing signed by Executive and by a duly authorized officer of the Company, and
such waiver is set forth in writing and signed by the party to be charged. No
waiver by either party hereto at any time of any breach by the other party
hereto of any condition or provision of this Agreement to be performed by such
other party shall be deemed a waiver of similar or dissimilar provisions or
conditions at the same or at any prior or subsequent time. No agreements or
representations, oral or otherwise, express or implied, with respect to the
subject matter hereof have been made by either party which are not set forth
expressly in this Agreement. The respective rights and obligations of the
parties hereunder of this Agreement shall survive Executive's termination of
employment and the termination of this Agreement to the extent necessary for the
intended preservation of such rights and obligations. The validity,
interpretation, construction and performance of this Agreement shall be governed
by the laws of the State of New York without regard to its conflicts of law
principles. By signing this Agreement, Executive acknowledges that he will not
be an officer of the Company and that during the Employment Period he will not
hold himself out to the public or any other party as an officer of the Company.

        14.     Validity. The invalidity or unenforceability of any provision or
provisions of this Agreement shall not affect the validity or enforceability of
any other provision of this Agreement, which shall remain in full force and
effect.

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

        16.     Entire Agreement. Except as other provided herein, this
Agreement sets forth the entire agreement of the parties hereto in respect of
the subject matter contained herein and supersede all prior agreements,
promises, covenants, arrangements, communications, representations or
warranties, whether oral or written, by any officer, employee or representative
of any party hereto in respect of such subject matter. Except as other provided
herein, any prior

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agreement of the parties hereto in respect of the subject matter contained
herein is hereby terminated and cancelled.

        17.     Withholding. All payments hereunder shall be subject to any
required withholding of Federal, state and local taxes pursuant to any
applicable law or regulation.

        18.     Section Headings. The section headings in this Agreement are for
convenience of reference only, and they form no part of this Agreement and shall
not affect its interpretation.

        19.     Representation. Executive represents and warrants to the
Company, and Executive acknowledges that the Company has relied on such
representations and warranties in employing Executive, that neither Executive's
duties as an employee of the Company nor his performance of this Agreement will
breach any other agreement to which Executive is a party, including without
limitation, any agreement limiting the use or disclosure of any information
acquired by Executive prior to his employment by the Company. In addition,
Executive represents and warrants and acknowledges that the Company has relied
on such representations and warranties in employing Executive, that he has not
entered into, and will not enter into, any agreement, either oral or written, in
conflict herewith.

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                  IN WITNESS WHEREOF, the parties hereto have executed this
Agreement on the date first above written.

                          IMCLONE SYSTEMS INCORPORATED

                              /S/ Daniel S. Lynch
                          By:
                              ------------------------
                              Name:   Daniel S. Lynch
                              Title:  Senior Vice President - Finance
                                      & Chief Financial Officer

                          Executive:

                              /S/ Clifford R. Saffron
                              ------------------------
                              Name:   Clifford R. Saffron

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                                                       EXHIBIT 10.90 - AMENDMENT

                                             As of April 18, 2002

Clifford R. Saffron, Esq.
120 Redwood Drive
Roslyn, NY  11576

Dear Cliff:

         Reference is made to the Employment Agreement between the Company and
yourself dated as of February 1, 2002 (the "Agreement"). That Agreement provides
the terms of your employment by ImClone Systems Incorporated commencing February
1, 2002, and it is the intent of the Company and yourself through this letter
amendment (the "Amendment") to make certain changes to the Agreement, as
follows:

         In Section 1, "Employment", your title, reflected in the Agreement as
Vice President and Special General Counsel (SGC), shall be changed to "Senior
Vice President and Special General Counsel (SGC)".

         In addition to the Stock Option award set forth in Section 5(b) of the
Agreement, the Company awards you additional Stock Options as set forth below:

         The Board of Directors of the Company has approved a stock option grant
to Executive to acquire 10,000 shares of the Company's common stock (each, an
"Option" and collectively the "Options") at a price of $ 21.54 per share under
such terms and conditions as provided for under the Company's then existing
stock option plans which are not inconsistent with the following paragraph.

         The Options described in paragraph (i) above shall be granted subject
to the following terms and conditions: (A) except as provided below, the Options
shall be granted under and subject to the Company's stock option plan; (B) the
exercise price per share of each Option shall be $ 21.54, which was the closing
price of the Company's common stock on the NASDAQ (or such other principal
trading market for the Company's common stock) on April 18, 2002, the date that
this grant was approved by the Board; (C) the Options shall be vested and
exercisable as to 25% of the shares subject thereto on each of the first,
second, third and fourth anniversaries of the date of grant; provided, that,
Executive is then employed; (D) each Option shall be exercisable for the ten
(10) year period following the date of grant; provided, that, Executive is then
employed; and (E) each Option shall be evidenced by, and subject to, a stock
option
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agreement whose terms and conditions are consistent with the terms of
employees of the Company who are at a vice president level.

         "Section 5(c) of the Agreement is amended to add the following
additional language: "In addition, during the Employment Period, the Company
shall provide the Executive a reasonable automobile allowance as determined by
the CEO".

         In all other aspects the Agreement remains unchanged.

         Kindly enter into the Amendment by signing below.

                                          Very truly yours,

                                          /S/ Daniel S. Lynch

                                          Daniel S. Lynch
                                          Senior Vice President,
                                          Chief Financial Officer and Secretary

         Agreed to:

         /S/ Clifford R. Saffron
         ----------------------------
         Clifford R. Saffron<PAGE>
                                                                 EXHIBIT  10.91

                              SEPARATION AGREEMENT
                               (SAMUEL D. WAKSAL)

                  SEPARATION AGREEMENT, dated as of May 22, 2002 ("Agreement"),
between IMCLONE SYSTEMS INCORPORATED, a Delaware corporation (the "Company"),
and SAMUEL D. WAKSAL (the "Executive"). Capitalized terms used herein but not
defined herein shall have the meanings given to them in the Employment
Agreement, dated as of September 19, 2001 (the "Employment Agreement"), between
the Company and the Executive.

SECTION 1. RESIGNATION. In consideration of the Company's agreements hereunder,
the Executive hereby resigns from all directorships, offices and positions with
the Company and its subsidiaries, affiliates and employee benefit plans and
trusts, effective May 22, 2002 (the "Date of Termination"). The Executive and
the Company hereby agree that the Employment Period shall be terminated as of
the Date of Termination.

SECTION 2. SEPARATION COMPENSATION. Within five (5) days following the Date of
Termination, the Company shall pay to Executive $7,000,000 (seven million
dollars).

SECTION 3. OTHER BENEFITS.

                (a) The Company shall maintain in full force and effect, for the
        continued benefit of Executive, his spouse and his dependents for a
        period of three (3) years following the Date of Termination the medical,
        hospitalization, dental, and life insurance programs in which Executive,
        his spouse and his dependents were participating immediately prior to
        the Date of Termination at the level in effect and upon substantially
        the same terms and conditions (including without limitation
        contributions required by Executive for such benefits) as existed
        immediately prior to the Date of Termination; provided, that, if
        Executive, his spouse or his dependents cannot continue to participate
        in the Company programs providing such benefits, the Company shall
        arrange to provide Executive, his spouse and his dependents with the
        economic equivalent of such benefits which they otherwise would have
        been entitled to receive under such plans and programs ("Continued
        Benefits"), provided, that, such Continued Benefits shall terminate on
        the date or dates Executive receives equivalent coverage and benefits,
        without waiting period or pre-existing condition limitations, under the
        plans and programs of a subsequent employer (such coverage and benefits
        to be determined on a coverage-by-coverage or benefit-by-benefit,
        basis).

                (b) Subject to the Executive's insurability, the Company shall
        purchase for the benefit of Executive or his designated beneficiaries a
        term life insurance policy with a death benefit of $5,000,000 to be
        maintained for 6 years following the Date of Termination.

                (c) The Company shall reimburse Executive in the manner provided
        in Section 5 of the Employment Agreement for reasonable expenses
        incurred, but not paid prior to the Date of Termination.
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                (d) The Executive shall be entitled to any other rights,
        compensation and/or benefits as may be due to the Executive as of the
        Date of Termination in accordance with the terms and provisions of any
        agreements (other than the Employment Agreement), plans or programs of
        the Company.

                (e) With respect to equity awards granted or made on or after
        September 19, 2001, notwithstanding the terms or conditions of any stock
        option, stock appreciation right, restricted stock or similar agreements
        between the Company and Executive to the contrary, and for purposes
        thereof, such agreements shall be deemed to be amended in accordance
        with this Section 3(e) if need be as of the Date of Termination and
        neither the Company, the Board nor the Committee shall take or assert
        any position contrary to the foregoing, such that Executive shall vest,
        as of the Date of Termination, in all rights under such agreements
        (e.g., stock options that would otherwise vest after the Date of
        Termination) and in the case of stock options, stock appreciation rights
        or similar awards, thereafter shall be permitted to exercise any and all
        such rights until the end of the term of such awards (regardless of any
        termination of employment restrictions therein contained) and restricted
        stock held by Executive shall become immediately vested as of the Date
        of Termination.

                (f) The Executive shall have the right to receive in connection
        with this Agreement any payments to which the Executive would have been
        entitled pursuant to Section 8(e) of the Employment Agreement.

                (g) The Company shall pay fees of the Executive's crisis
        management consultant incurred during the six months following the Date
        of Termination; provided that such fees do not exceed $25,000 per month.

                (h) The Company shall pay to the applicable advisors of the
        Executive, the Executive's legal fees incurred in connection with the
        negotiation of this Agreement up to a maximum of $35,000.

SECTION 4. RESTRICTIVE COVENANTS.

                (a) CONFIDENTIALITY. The Executive shall not, without the prior
        written consent of the Company or as may otherwise be required by
        applicable law or legal process, or as is necessary in connection with
        any adversarial proceeding against the Company (in which cases Executive
        shall use his reasonable best efforts in cooperating with the Company in
        obtaining a protective order against disclosure by a court of competent
        jurisdiction) at any time use, divulge or convey any trade secrets or
        confidential information, knowledge or data relating to the Company or
        its affiliates and their respective businesses and investments
        (including information, knowledge or data of third parties as to which
        the Company or an affiliate is under an obligation of confidentiality),
        which is not generally available public knowledge (other than
        information that became public knowledge as a result of acts by
        Executive in violation of this Agreement).

                (b) NON-SOLICITATION. The Executive hereby agrees, in
        consideration of the payments to him hereunder, that from the Date of
        Termination through the first
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        anniversary of the Date of Termination, Executive shall not directly or
        indirectly induce any employee of the Company to terminate such
        employment or to become employed by any other biopharmaceutical company.

                (c) NON-COMPETITION. The Executive hereby agrees, in
        consideration of the payments to him hereunder, that from the Date of
        Termination through the first anniversary of the Date of Termination, he
        shall not be employed by or perform activities on behalf of, or have an
        ownership interest in, any person, firm, corporation or other entity, or
        in connection with any business enterprise, that is directly or
        indirectly engaged in any of the biopharmaceutical businesses in which
        the Company and its subsidiaries have significant involvement (other
        than by means of Executive's direct or beneficial ownership of up to one
        percent (1%) of any entity whether or not such entity is in the same or
        competing business); provided that nothing in this Section 4(c) shall
        restrict the Executive's current relationships with Scientia Health
        Group Inc., Antigenics, Cibus Genetics LLC, Berleley Heart Lab,
        Microbes, Prototek II, Inc., Tribeca Pharmaceutical Corporation and
        Valigen, N.V.

                (d) BLUE PENCIL. The parties hereby acknowledge that the
        restrictions in this Section 4 have been specifically negotiated and
        agreed to by the parties hereto and are limited only to those
        restrictions necessary to protect the Company and its subsidiaries from
        the misuse of confidential information and unfair competition. The
        parties hereby agree that if the scope or enforceability of any
        provision, paragraph or subparagraph of this Section 4 is in any way
        disputed at any time, and should a court find that such restrictions are
        overly broad, the court may modify and enforce the covenant to the
        extent that it believes it to be reasonable under the circumstances.
        Each provision, paragraph and subparagraph of this Section 4 is
        separable from every other provision, paragraph, and subparagraph and
        constitutes a separate and distinct covenant. Executive acknowledges
        that the Company's business is not limited by geographical scope, is
        operating throughout the world and that the effect of Section 4(c) may
        be to prevent him from working in a competitive business after his
        termination of employment hereunder.

SECTION 5. SPECIFIC PERFORMANCE. The Executive acknowledges and agrees that the
Company's remedies at law for a breach or threatened breach of any of the
provisions of Section 4 would be inadequate and the Company would suffer
irreparable damages as a result of such breach or threatened breach. In
recognition of this fact, the Executive agrees that, in the event of such a
breach or threatened breach, in addition to any remedies at law, the Company,
without posting any bond, shall, notwithstanding Section 17 of this Agreement,
be entitled to bring an action in any court of competent jurisdiction for the
purpose of obtaining equitable relief in the form of specific performance,
temporary restraining order, temporary or permanent injunction or any other
equitable remedy which may then be available.

SECTION 6. COOPERATION. The Executive shall provide reasonable cooperation in
connection with any action, investigation or proceeding which relates to the
Company or any of its affiliates, including without limitation in connection
with any litigation and disputes arising out of actions or inactions of the
Company or any affiliate of which the Executive has knowledge or information;
provided that such cooperation does not unreasonably interfere with the
Executive's other pursuits or undertakings. The Executive further agrees to
cooperate with the Company in supplying data, information, and expertise within
the Executive's special knowledge or competence and otherwise assist the Company
in the protection of the interests of the Company
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                                                                               4

and its affiliates; provided that such cooperation does not unreasonably
interfere with the Executive's other pursuits or undertakings. The Company shall
reimburse the Executive for reasonable out-of-pocket expenses incurred by the
Executive in connection with such cooperation following its receipt of the
Executive's appropriately itemized request.

SECTION 7. INDEMNITY. The existing rights of the Executive and obligations of
the Company with regard to indemnification of the Executive that are not
dependent upon Executive's continued employment or holding an office or
directorship with the Company or an affiliate, and the indemnification rights
under the Company's current certificate of incorporation and by-laws, shall
continue.

SECTION 8. NON-DISPARAGEMENT. The Company and its affiliates shall refrain from
making any statements or comments of a defamatory or disparaging nature to any
third party regarding the Executive, and the Executive shall refrain from making
any statements or comments of a defamatory or disparaging nature to any third
party regarding the Company, any of its affiliates, or any of their directors,
officers, personnel, policies or product; provided, however, that it shall not
be a violation of this Section 8 for either party to make truthful statements
when required to do so by a court of law, by any governmental agency having
supervisory authority over the party, or by any administrative or legislative
body with apparent jurisdiction to order the party to divulge, disclose or make
accessible such information or as may otherwise be required to defend any
allegations or statements made by the other party.

SECTION 9. SEVERABILITY. In the event that any one or more of the provisions of
this Agreement shall be or become invalid, illegal or unenforceable in any
respect, the validity, legality and enforceability of the remaining provisions
of this Agreement shall not be affected thereby.

SECTION 10. ASSIGNMENT. This Agreement, and all of Executive's rights and duties
hereunder, shall not be assignable or delegable by Executive. Any purported
assignment or delegation by Executive in violation of the foregoing shall be
null and void ab initio and of no force and effect. This Agreement may be
assigned by the Company to a person or entity which is a successor in interest
to substantially all of the business operations of the Company. Upon such
assignment, the rights and obligations of the Company hereunder shall become the
rights and obligations of such successor person or entity.

SECTION 11. NO MITIGATION. Executive shall not be required to mitigate the
amount of any payment provided for pursuant to this Agreement by seeking other
employment, and, except as may be required pursuant to Section 3(a) of this
Agreement, the Executive shall not be required to pay the Company any amounts
the Executive may receive from such alternative employment. Additionally,
amounts owed to the Executive under this Agreement shall not be offset by any
claims the Company may have against the Executive.

SECTION 12. SUCCESSORS; BINDING AGREEMENT. This Agreement shall inure to the
benefit of and be binding upon personal or legal representatives, executors,
administrators, successors, heirs, distributees, devisees and legatees.

SECTION 13. NOTICE. For purposes of this Agreement, notices and all other
communications provided for in this Agreement shall be in writing and shall be
deemed to have been duly given when delivered by hand or overnight courier or
three days after it has been mailed by United States registered mail, return
receipt requested, postage prepaid, addressed to the respective
<PAGE>
                                                                               5

addresses set forth below in this Agreement, or to such other address as either
party may have furnished to the other in writing in accordance herewith, except
that notice of change of address shall be effective only upon receipt.

                  Notice to the Company shall be addressed to:

                           ImClone Systems Incorporated
                           180 Varick Street
                           New York, New York 10014
                           Attn:  Chief Financial Officer

                  Notice to the Executive shall be addressed to:

                           Dr. Samuel D. Waksal
                           150 Thompson Street, Apt. 5C
                           New York, NY 10012

SECTION 14. WITHHOLDING TAXES. The Company may withhold from any amounts payable
under this Agreement such Federal, state and local taxes as may be required to
be withheld pursuant to any applicable law or regulation.

SECTION 15. ENTIRE AGREEMENT/AMENDMENTS. This Agreement contains the entire
understanding of the parties with respect to the subject matter hereof and
supersedes the Employment Agreement, which shall terminate as of the date
hereof. For the avoidance of doubt, the Discovery and Non-Disclosure Agreement,
dated as of July 15, 1986, between the Company and the Executive shall survive.
This Agreement may not be amended except by written instrument signed by the
parties hereto.

SECTION 16. NO WAIVER. The failure of a party to insist upon strict adherence to
any term of this Agreement on any occasion shall not be considered a waiver of
such party's rights or deprive such party of the right thereafter to insist upon
strict adherence to that term or any other term of this Agreement.

SECTION 17. ARBITRATION. Except as set forth in Section 5 of this Agreement, any
dispute, controversy or claim arising out of or relating to this Agreement shall
be settled exclusively by binding arbitration for resolution in New York, New
York in accordance with the rules and procedures of the Employment Dispute
Resolution Rules of the American Arbitration Association. The decision of the
arbitrator shall be final and binding on both parties, and any court of
competent jurisdiction may enter judgment upon the award. The Company shall pay
all expenses relating to such arbitration, including but not limited to, the
Executive's legal fees and expenses, regardless of outcome, unless the
arbitrator determines that the Executive has acted in bad faith.

SECTION 18. GOVERNING LAW; VENUE. This Agreement shall be governed by and
construed in accordance with the laws of the State of New York, without regard
to conflicts of laws principles thereof. Except as provided in Section 17 of
this Agreement, the Executive irrevocably submits to the non-exclusive
jurisdiction of the courts of the State of New York and the courts of the United
States located in the State of New York for the purpose of any action or
proceeding
<PAGE>
                                                                               6

arising out of or relating to this Agreement, and acknowledges that the
designated fora have a reasonable relation to this Agreement and the parties'
relationship to one another.

SECTION 19. COUNTERPARTS. This Agreement may be signed in counterparts, each of
which shall be an original, with the same effect as if the signatures thereto
and hereto were upon the same instrument.

                   IN WITNESS WHEREOF, the parties hereto have executed this
Agreement as of the day and year first written above.

                                                 IMCLONE SYSTEMS INCORPORATED

                                                 /S/ Daniel S. Lynch
                                                 ------------------------------
                                                 BY:  DANIEL S. LYNCH
                                                 TITLE: CFO

                                                 /S/ Samuel D. Waksal, Ph.D.
                                                 ------------------------------
                                                 SAMUEL D. WAKSAL, PH.D.

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