**Exhibit 10.42**

March 21, 2006

Mr. Joseph L. Fischer61 Lake RoadFar Hills, NJ  07931

Dear Joe,

Thepurpose of this letter (the “*Letter Agreement*”)is to set forth our agreement with respect to your employment with ImClone Systems Incorporated (“*ImClone*”) as its Interim Chief Executive Officer,which position you assumed on January 24, 2006 (the “*EffectiveDate*”).
| Title/Location |   | You will serve as ImClone’s Interim Chief Executive  Officer. Your primary place of business will be ImClone’s Branchburg, NJ  office and is subject to business travel.                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|           |   | You  have also been previously elected to serve as a member of the Board, which  service you will perform at no additional compensation, other than  (x) the award of a stock option in respect of 20,000 shares of common  stock which you were previously granted on January 18, 2006 in respect  of your service on the Board and (y) a pro-rated portion of the annual  $20,000 fee payable to non-employee directors in respect of 2006 service  (with such pro-ration reflecting service on the Board through  January 23, 2006) and payments for Board committee meetings attended through  January 23, 2006. |
| Salary         |   | ImClone will pay you a  base salary at a rate of $40,000 per month, payable in accordance with  ImClone’s customary payroll practices.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Benefits       |   | You will be eligible to  participate in the employee benefit plans and arrangements of ImClone,  subject to their terms and procedures (including election procedures), as  they may be modified from time to time. You will be eligible for one hundred  sixty (160) hours of vacation per year, subject to the terms and conditions  of ImClone’s vacation policy.                                                                                                                                                                                                                                                                     |
| Annual Bonus   |   | The Compensation  Committee of the Board of Directors of ImClone (respectively, the “*Compensation Committee*” and the “*Board*”)  has approved a 2006 annual bonus opportunity for you, with a target of  $500,000 and a maximum opportunity of $1 million, payable under and subject  to the terms of ImClone’s Annual Incentive Plan. The criteria for your 2006  annual bonus will be established by the Compensation Committee at the time  annual bonus criteria for 2006 are established for other senior executives  under ImClone’s Annual Incentive Plan.                                             |

----

 

|                    |   | Any annual bonus  opportunities in respect of future years will be established by the  Compensation Committee in its discretion.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|--------------------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Employment  Term   |   | You will be an at-will employee of ImClone. Your employment may be terminated  at any time by ImClone. You may terminate your employment at any time,  provided that you give ImClone at least 60 days’ advance written notice of  your intent to terminate your employment.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Severance          |   | In the event your employment is terminated by  ImClone without “Cause” (as defined on Appendix A), or in the event  you terminate your employment with ImClone with “Good Reason” (as defined on Appendix  A) following a “Change in Control” (as defined on Appendix A), you  will be entitled to a lump sum cash severance payment of not less than  $500,000, payable no later than 10 days following your termination of  employment (subject to six months’ delay as and if required under  Section 409A of the Internal Revenue Code of 1968, as amended (the “*Code*”)).                                                                                                                                                                                            |
|               |   | In the event of your  termination of employment with ImClone for any other reason, you will not be  entitled to any severance or termination payments or benefits (other than  those vested accrued benefits to which you may be entitled under the ImClone  employee benefit plans in which you were participating at the time of your  termination of employment). As Interim Chief Executive Officer you will be  designated as a “limited duration” employee for purposes of ImClone’s Senior  Executive Severance Plan and will, therefore, not be covered under that plan.  You also will not be covered (by virtue of rank or otherwise) under ImClone’s  Change-In-Control Plan unless the Compensation Committee specifically  designates you in writing as a covered employee under that plan. |
| Release            |   | Your severance  entitlements, as described herein, will be subject to your execution and  non-revocation of a general release of all claims against ImClone and its  Subsidiaries, affiliates and related persons (other than claims for  indemnification, claims for vested accrued benefits under the employee  benefit plans in which you were participating at the time of your termination  of employment, and claims for the severance amounts described herein), in  such form as is required by ImClone.                                                                                                                                                                                                                                                                                                             |
| Gross-Up           |   | In the event that you  become subject to the excise tax imposed by Code Section 4999 (the  “Parachute Excise Tax”), then you will be entitled to gross-up payments from  ImClone on the terms, and subject to the conditions and limitations, set  forth in Appendix B.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Equity  Incentives |   | The Compensation Committee previously granted you, in respect of your  appointment as Interim Chief Executive Officer, a non-qualified stock option  under ImClone’s 2002 Stock Option Plan to purchase 100,000 shares of  ImClone’s common stock at an exercise price equal to the closing price of  ImClone’s common stock on the date of grant (i.e., February 28, 2006). This award is subject to the  terms and conditions of the applicable plan and award agreement.                                                                                                                                                                                                                                                                                                                              |

2

----

 

| Covenants       |   | The confidentiality, non-competition  and non-solicitation provisions set forth in Appendix C (and other  applicable Company policies) will apply to you in all events and regardless  of the reason for your termination of employment.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Indemnification |   | You will be entitled to be indemnified, in  accordance with, and subject to the terms and conditions of, ImClone’s  by-laws, for actions and omissions as an officer of ImClone.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Notice          |   | Communications relating  to this Letter Agreement will be in writing and will be deemed to have been duly  given when delivered either personally or by United States certified mail,  return receipt requested, addressed as follows:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|            |   | If to you:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|            |   | at the address listed in  ImClone’s personnel records                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|            |   | If to ImClone:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|            |   | ImClone Systems  Incorporated                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|            |   | 180 Varick Street                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|            |   | New York, New York 10014                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|            |   | Attention: General Counsel                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Miscellaneous   |   | This Letter Agreement  (which includes the Appendices hereto) represents the entire agreement  between the parties with respect to the subject matters herein. Any rights and  obligations you may have as a result of this Letter Agreement may not be  transferred, except that any amounts constituting earned but unpaid base  salary as of the time of your death may be paid to your estate. This Letter  Agreement will be governed by the laws of the State of New York without  regard to its conflicts of law principles. This Letter Agreement may be  executed in one or more counterparts, each of which will be deemed to be an  original but all of which together will constitute one and the same instrument.  This Letter Agreement may be amended only by a written instrument signed by  the parties hereto. |

 

Kindly acknowledge the terms above by signing belowand returning this form to me.

Sincerely,

ImCloneSystems Incorporated
| /s/ LISA M. CAMMY                              |   |
|------------------------------------------------|--------|
| Lisa M. Cammy, Vice President, Human Resources |   |

 

ACCEPTEDAND ACKNOWLEDGED
| /s/ JOSEPH  L. FISCHER |   |
|------------------------|--------|
| Joseph L. Fischer      |   |

 

3

----

***Appendix A - Definitions***

1)               “*Cause”*will mean the occurrence of any of the following:

(a)          an indictment for, aconviction of, or a plea of guilty or nolo contendere to, a felony or amisdemeanor involving fraud, embezzlement, or moral turpitude;

(b)         willful misconduct orgross negligence by you resulting, in either case, in harm to ImClone or any Subsidiary(reputational or economic);

(c)          failure by you to attemptin good faith to (x) perform your duties to ImClone or (y) carry outthe directions of the Board, in either case after written notice to you of suchfailure; or

(d)         fraud, embezzlement,theft or dishonesty by you against ImClone or any Subsidiary or a materialviolation by you of a policy or procedure of ImClone, resulting, in any case,in harm to ImClone or any Subsidiary (reputational or economic).

2)               *“Change in Control”* will mean theoccurrence of one of the following events during your employment with ImCloneunder this Letter Agreement:

(a)          individuals who, on the EffectiveDate, constitute the Board (the “*Incumbent Directors*”)cease for any reason to constitute at least a majority of the Board, providedthat any person becoming a director subsequent to the Effective Date whoseelection or nomination for election was approved by a vote of at leasttwo-thirds of the Incumbent Directors then on the Board (either by a specificvote or by approval of the proxy statement of ImClone in which such person isnamed as a nominee for director, without objection to such nomination) will bean Incumbent Director; provided, however, that no individual initially electedor nominated as a director of ImClone as a result of an actual or threatenedelection contest with respect to directors or as a result of any other actualor threatened solicitation of proxies by or on behalf of any person other thanthe Board will be an Incumbent Director;

(b)         any “person” (as suchterm is defined in Section 3(a)(9) of the Securities Exchange Act of1934 (the “*Exchange Act*”) and as used in Sections13(d)(3) and 14(d)(2) of the Exchange Act) is or becomes, after theEffective Date, a “beneficial owner” (as defined in Rule 13d-3 underthe Exchange Act), directly or indirectly, of securities of ImClonerepresenting 40% or more of the combined voting power of ImClone’s thenoutstanding securities eligible to vote for the election of the Board (the “*Company Voting Securities*”); provided, however, that anevent described in this paragraph (b) will not be deemed to be a Change inControl if any of following becomes such a beneficial owner:

(i)             ImClone or anymajority-owned Subsidiary (provided, that this exclusion applies solely to theownership levels of ImClone or the majority-owned Subsidiary);

(ii)         any tax-qualified,broad-based employee benefit plan sponsored or maintained by ImClone or anymajority-owned Subsidiary;

(iii)     any underwriter temporarilyholding securities pursuant to an offering of such securities; or

(iv)       any person pursuant to aNon-Qualifying Transaction (as defined below);

(c)          the consummation of amerger, consolidation, statutory share exchange or similar form of corporatetransaction involving ImClone or any of its Subsidiaries that requires theapproval of ImClone’s stockholders, whether for such transaction or theissuance of securities in the transaction (a “*BusinessCombination*”), unless immediately following such BusinessCombination:

(i)             50% or more of thetotal voting power of:

4

----

(A)       the corporation resultingfrom such Business Combination (the “*Surviving Corporation*”),or

(B)        if applicable, theultimate parent corporation that directly or indirectly has beneficialownership of 100% of the voting securities eligible to elect directors of theSurviving Corporation (the “*Parent Corporation*”),

is represented byCompany Voting Securities that were outstanding immediately prior to suchBusiness Combination (or, if applicable, is represented by shares into whichsuch Company Voting Securities were converted pursuant to such BusinessCombination), and such voting power among the holders thereof is insubstantially the same proportion as the voting power of such Company VotingSecurities among the holders thereof immediately prior to the BusinessCombination;

(ii)         no person (other than anyemployee benefit plan (or related trust) sponsored or maintained by theSurviving Corporation or the Parent Corporation), is or becomes the beneficialowner, directly or indirectly, of 40% or more of the total voting power of theoutstanding voting securities eligible to elect directors of the ParentCorporation (or, if there is no Parent Corporation, the Surviving Corporation);and

(iii)     at least a majority of themembers of the board of directors of the Parent Corporation (or if there is noParent Corporation, the Surviving Corporation) following the consummation ofthe Business Combination were Incumbent Directors at the time of the Board’sapproval of the execution of the initial agreement providing for such BusinessCombination;

(any BusinessCombination which satisfies all of the criteria specified in (i), (ii) and(iii) above will be deemed to be a “*Non-Qualifying Transaction*”);or

(d)         stockholder approval of aliquidation or dissolution of ImClone, unless the voting common equityinterests of an ongoing entity (other than a liquidating trust) arebeneficially owned, directly or indirectly, by ImClone’s shareholders in substantiallythe same proportions as such shareholders owned ImClone’s outstanding votingcommon equity interests immediately prior to such liquidation and such ongoingentity assumes all existing obligations of ImClone under this Letter Agreement.

Notwithstanding theforegoing, a Change in Control of ImClone will not be deemed to occur solelybecause any person acquires beneficial ownership of more than 40% of ImCloneVoting Securities as a result of the acquisition of Company Voting Securitiesby ImClone which reduces the number of Company Voting Securities outstanding;provided, that, if after such acquisition by ImClone such person becomes thebeneficial owner of Company Voting Securities that increases the percentage ofoutstanding Company Voting Securities beneficially owned by such person, aChange in Control of ImClone will then occur.

3)               *“Good Reason”* will mean the occurrence ofany of the following events after a Change in Control, provided you notifyImClone in writing at least 60 days after such event of your intent toterminate your employment as a result thereof and ImClone does not cure suchevent within 30 days after such notice:

(a)          a material adversediminution of your titles, authority, duties or responsibilities, or theassignment to you of titles, authority, duties or responsibilities that arematerially inconsistent with your titles, authority, duties and/orresponsibilities in a manner materially adverse to you; or

(b)         a reduction in your basesalary, or a reduction in your target bonus opportunity in respect of 2006 asdescribed in the Letter Agreement, without your prior written consent; or

5

----

(c)          an actual change in yourprincipal work location by more than 75 miles and more than 75 miles from your principalplace of abode as of the date of such change in job location without your priorwritten consent; or

(d)         a failure of ImClone toobtain the assumption in writing of its obligation under this Letter Agreement byany successor to all or substantially all of the assets of ImClone within 45days after a merger, consolidation, sale or similar transaction that qualifiesas a Change in Control.

4)               *“Subsidiary”* will mean a corporation ofwhich ImClone directly or indirectly owns more than 50 percent of the “votingstock” (meaning the capital stock of any class or classes having general votingpower under ordinary circumstances, in the absence of contingencies, to electthe directors of a corporation) or any other business entity in which ImClone directlyor indirectly has an ownership interest of more than 50 percent.

6

----

 

***Appendix B—Tax Provisions***

**1)**   Withholding Taxes.****   ImClonewill be entitled to withhold from any and all payments made to you under thisLetter Agreement all federal, state, local and/or other taxes or imposts which ImClonedetermines are required to be so withheld from such payments.

**2)**   Golden Parachute Taxes.****   Inthe event that you become subject to the excise tax imposed by Code Section 4999(the “*Parachute Excise Tax*”), then you and ImClonewill carry out the following:

(a)    If theaggregate “parachute payment” (as such term is used under Code Section 280G)exceeds 299.99% of the “base amount” (as such term is used under Code Section 280G)(the “*Safe Harbor Amount*”) by less than 10% ofthe Safe Harbor Amount, then the parachute payment will be reduced to the SafeHarbor Amount, with you determining in your sole discretion which portion ofthe aggregate parachute payment will be so reduced; or

(b)   If theaggregate parachute payment exceeds the Safe Harbor Amount by 10% or more ofthe Safe Harbor Amount, then ImClone will pay you a tax gross-up payment sothat after payment by you of all federal, state, and local excise, income,employment, Medicare and any other taxes (including any related penalties andinterest) resulting from the payment of the parachute payments and the taxgross-up payments to you by ImClone, you retain on an after-tax basis an amountequal to the amount that you would have retained had you not been subject tothe Parachute Excise Tax.

**3)**   Section 409A.****   ImCloneintends that all payments under this Letter Agreement be made on a basis thatcomplies with Section 409A of the Code. Accordingly, in the event that youare considered a “Specified Employee” as defined in Section 409A of theCode or the guidance issued thereunder (“*Section 409A*”),and any payments to you under this Letter Agreement are considered “deferredcompensation” under Section 409A of a type requiring payment six monthsafter the date of your separation from service (within the meaning of Section 409A),then to the extent required by Section 409A, such payment will be delayeduntil six (6) months after the date of your separation from service.

**4)**   No Representations.****   ImClonemakes no representation, commitment or guarantee with respect to the taxtreatment of any payments hereunder, including, but not limited to, federal,state and local income, estate and gift tax treatment, and ImClone will not beresponsible in any event with regard to non-compliance with Code Section 409A.

7

----

***Appendix C—Covenants***

**1)****   Noncompetition.****  **During your employment with ImClone andfor a period of 12 months following your termination of employment for anyreason (the “*Noncompetition/Nonsolicitation Period*”)you will not at any time, directly or indirectly, engage in “CompetitiveActivity.”  For purposes of this LetterAgreement, “*Competitive Activity*”will mean your engaging in an activity, whether as an employee, consultant, principal,member, agent, officer, director, partner or shareholder (except as a less than1% shareholder of a publicly traded company) that is competitive with anybusiness of ImClone or any Subsidiary conducted by ImClone or such Subsidiaryat any time during the Noncompetition/Nonsolicitation Period;*provided, however*, that you may beemployed by or otherwise associated with (a) a business of which a Subsidiary,division, segment or unit is in competition with ImClone or any Subsidiary butas to which such Subsidiary, division, segment or unit you have absolutely nodirect or indirect responsibilities or involvement, or (b) a company wherethe Competitive Activity is (i) from the perspective of such company,*de minimis* with respect to the businessof such company and its affiliates, and (ii) from the perspective ofImClone or any Subsidiary, not in material competition with ImClone or any Subsidiary.

**2)****   Nonsolicitation.**   Duringthe Noncompetition/Nonsolicitation Period, you will not at any time, directlyor indirectly, solicit (x) any customer or client of ImClone or any Subsidiarywith respect to a Competitive Activity or (y) any employee of ImClone orany Subsidiary for the purpose of causing such employee to terminate his or heremployment with ImClone or such Subsidiary.

**3)****   Enforcement.****  **You acknowledge and agree that if youviolate or threaten to violate Section 1 or Section 2 of thisAppendix C, ImClone will not have an adequate remedy at law. Accordingly, youand ImClone agree that ImClone will be entitled to such equitable andinjunctive relief as may be available to restrain you and any business, firm,partnership, individual, corporation or entity participating in the breach orthreatened breach from the violation of the provisions of Section 1 or Section 2of this Appendix C.  Nothing in thisLetter Agreement will be construed as prohibiting ImClone from pursuing anyother remedies available at law or in equity for breach or threatened breach ofSection 1 or Section 2 of this Appendix C, including the recovery ofdamages.

**4)****   Confidentiality.**   Atall times prior to and after the termination of your service with ImClone forany reason, you will not disclose to anyone or make use of any trade secret orproprietary or confidential information of ImClone, including such trade secretor proprietary or confidential information of any customer or other entity towhich ImClone owes an obligation not to disclose such information, which you acquireduring your service with ImClone, including but not limited to records kept inthe ordinary course of business, except: (i) as such disclosure or use maybe required or appropriate in connection with your service as an employee of ImClone;(ii) when required to do so by a court of law, by any governmental agencyhaving supervisory authority over the business of ImClone or by anyadministrative or legislative body (including a committee thereof) withapparent jurisdiction to order you to divulge, disclose or make accessible suchinformation; (iii) as to such confidential information that becomesgenerally known to the public or trade without your violation of this Section 4of this Appendix C; or (iv) to your spouse and/or your personal tax andfinancial advisors as reasonably necessary or appropriate to advance your tax,financial and other personal planning (each an “*ExemptPerson*”),*provided, however*,that any disclosure or use of any trade secret or proprietary or confidentialinformation of ImClone by an Exempt Person will be deemed to be a breach ofthis Section 4 of this Appendix C by you.

**5)**   Return of Company Property.****   Immediatelyfollowing your termination of employment with ImClone for any reason, you willimmediately return all Company property in your possession, including but notlimited to all computer equipment (hardware and software), telephones,facsimile machines, palm pilots and other communication devices, credit cards,office keys, security access cards, badges, 

8

----

identification cards andall copies (including drafts) of any documentation or information (howeverstored) relating to the business of ImClone, its customers and clients or itsprospective customers and clients.

**6)****   Cooperation.**   Followingyour termination of employment with the Company for any reason, you will give yourassistance and cooperation willingly, upon reasonable advance notice with dueconsideration for your other business or personal commitments, in any matterrelating to your position with ImClone, or your expertise or experience as ImClonemay reasonably request, including your attendance and truthful testimony wheredeemed appropriate by ImClone, with respect to any investigation or ImClone’sdefense or prosecution of any existing or future claims or litigations or otherproceeding relating to matters in which you were involved or potentially hadknowledge by virtue of your service with ImClone. In no event will your cooperationmaterially interfere with your services for a subsequent employer or othersimilar service recipient. ImClone agrees that (i) it will promptlyreimburse you for your reasonable and documented expenses in connection with yourrendering assistance and/or cooperation under this Section 6 of thisAppendix C, upon your presentation of documentation for such expenses and (ii) youwill be reasonably compensated for any continued material services as requiredunder this Section 6 of this Appendix C.

9

----