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Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

¨

Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

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harmful micro-organisms;

•

cells containing foreign proteins known as antigens; and

•

disease-causing combinations of antigens and antibodies known as immune complexes.

•

cardiopulmonary bypass surgery;

•

acute myocardial infarction or heart attack;

•

unstable angina or painful chest pains associated with an insufficient blood supply to the heart;

•

angioplasty or procedures for opening up narrowed or blocked arteries that supply the heart; and

•

stroke and other peripheral vascular or blood circulatory diseases.

•

rheumatoid arthritis;

•

kidney diseases;

•

lupus;

•

inflammatory bowel diseases;

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inflammatory skin and muscle disorders;

•

multiple sclerosis; and

•

paroxysmal nocturnal hemoglobinuria, or PNH.

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(a)

dissolving clots that block heart vessels

(b)

percutaneous transluminal coronary angioplasty or PTCA, a procedure for opening up narrowed or blocked arteries that supply blood to the heart

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activation of white blood cells;

•

attraction of white blood cells;

•

production of injurious hormones including tumor necrosis factor-alpha;

•

activation of blood vessel-lining cells called endothelial cells, allowing leakage of white blood cells into tissue;

•

activation of blood-clotting cells called platelets; and

•

lysis of red blood cells that are deficient in complement inhibitors.

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preventing inflammation during cardiopulmonary bypass;

•

reducing heart tissue damage during myocardial infarction;

•

reducing brain damage in cerebral ischemia or reduced blood flow to brain tissue;

•

enhancing survival in a model of lupus;

•

preserving kidney function in nephritis or inflammation of kidney tissue; and

•

preventing lysis of red blood cells.

•

inflammation during cardiopulmonary bypass surgery;

•

heart tissue damage during cardiopulmonary bypass surgery;

•

new cognitive or mental faculty deficits after cardiopulmonary bypass surgery;

•

an objective measure of disease activity in rheumatoid arthritis patients; and

•

the incidence of proteinuria or abnormal loss of substantial amounts of protein in a patient’s urine in lupus patients.

•

closely tied to the production of activated complement byproducts;

•

characterized by clear development pathways;

•

inadequately treated by current therapies; and

•

associated with substantial health care costs.

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the incidence of death;

•

the incidence of heart tissue damage;

•

the incidence of stroke or brain tissue damage;

•

post-operative or after surgery complications;

•

the time spent by patients in the intensive care unit or ICU;

•

the scope of required treatments associated with CPB; and

•

perioperative bleeding resulting in the need for blood transfusions.

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reduced the swelling in joints;

•

prevented the onset of erosion of joints;

•

reduced the inflammatory white blood cell infiltration into the joints;

•

prevented the spread of disease to additional joints;

•

blocked the onset of clinical signs of rheumatoid arthritis; and

•

reduced established disease.

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hypertension;

•

strokes;

•

infections;

•

anemia;

•

heart, lung and joint inflammation;

•

coma; and

•

death.

•

abnormally low levels of protein in the blood;

•

abnormal lipid or fat elevations;

•

a propensity for abnormal blood clotting; and

•

substantial swelling in the abdomen, under the skin and in the legs.

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scarring of the kidney;

•

breakdown of kidney tissue into the urine;

•

clogging of the kidney filtering units; and

•

proteinuria.

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the hyperacute phase, which is very rapid, extending from minutes to hours; and

•

the acute phase, which is somewhat less rapid, extending from days to months.

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the objectives of the study;

•

the parameters to be used to monitor safety; and

•

the efficacy criteria to be evaluated.

•

evaluate preliminarily the efficacy of the drug for specific, targeted indications;

•

determine dosage tolerance and optimal dosage; and

•

identify possible adverse effects and safety risks.

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substantially greater financial and other resources;

•

larger research and development staffs;

•

lower labor costs; and/or

•

more extensive marketing and manufacturing organizations.

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*

These employees are officers for purposes of Section 16 of the Securities Exchange Act of 1934.

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excludes non-cash IPRD, Amortization of GW, and Cumulative effect of adoption of SAB 101

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the progress, timing and scope of our research and development programs;

•

the progress, timing and scope of our preclinical studies and clinical trials;

•

the time and cost necessary to obtain regulatory approvals;

•

the time and cost necessary to further develop manufacturing processes, arrange for contract manufacturing or build manufacturing facilities and obtain the necessary regulatory approvals for those facilities;

•

the time and cost necessary to develop sales, marketing and distribution capabilities;

•

changes in applicable governmental regulatory policies; and

•

any new collaborative, licensing and other commercial relationships that we may establish.

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(1)

Member of our Audit Committee of the Board of Directors.

(2)

Member of our Compensation Committee of the Board of Directors.

(3)

Member of our Nominating Committee of the Board of Directors.

(4)

Officer, for purposes of Section 16 of the Securities Exchange Act of 1934.

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*

Less than one percent.

(1)

Unless otherwise indicated, the address of all persons is 352 Knotter Drive, Cheshire, Connecticut 06410.

(2)

To our knowledge, except as set forth below, the persons named in the table have sole voting and investment power with respect to all shares of common stock shown as beneficially owned by them, subject to community property laws where applicable and the information contained in the footnotes in this table.

(3)

This figure is based upon information set forth in Schedule 13F dated June 30, 2002.

(4)

This figure is based upon information set forth in Schedule 13F dated June 30, 2002.

(5)

This figure is based upon information set forth in Schedule 13F dated June 30, 2002.

(6)

Includes 602,391 shares of common stock that may be acquired upon the exercise of options within 60 days of October 1, 2002 and 300 shares, in aggregate, held in the names of Dr. Bell’s three children.

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Excludes 97,464 shares obtainable through the exercise of options, granted to Dr. Bell, which are not exercisable within 60 days of October 1, 2002 and 90,000 shares held in trust for Dr. Bell’s children of which Dr. Bell disclaims beneficial ownership. Dr. Bell disclaims beneficial ownership of the shares held in the names of his children.

(7)

Includes 214,058 shares of common stock which may be acquired upon the exercise of options within 60 days of October 1, 2002 and 300 shares, in aggregate, held in the names of Mr. Keiser’s three children. Excludes 44,942 shares obtainable through the exercise of options, granted to Mr. Keiser, which are not exercisable within 60 days of October 1, 2002. Mr. Keiser disclaims beneficial ownership of the shares held in the names of his minor children.

(8)

Includes 200,078 shares of common stock which may be acquired upon the exercise of options within 60 days of October 1, 2002; 6,106 shares held in trust for the benefit of Dr. Squinto’s three minor children of which Dr. Squinto’s spouse is the trustee; and 9,012 shares held in a charitable remainder trust of which Dr. Squinto and his spouse are the trustees and income beneficiaries. Excludes 36,422 shares obtainable through the exercise of options, granted to Dr. Squinto, which are not exercisable within 60 days of October 1, 2002. Dr. Squinto disclaims beneficial ownership of the shares held in the names of his minor children and the foregoing trusts.

(9)

Includes 11,167 shares of common stock, which may be acquired upon the exercise of options that are exercisable within 60 days of October 1, 2002. Excludes 16,500 obtainable through the exercise of options granted to Dr. Fried, which are not exercisable within 60 days of October 1, 2002.

(10)

Includes 21,300 shares of common stock which may be acquired on the exercise of options that are exercisable within 60 days of October 1, 2002. Excludes 16,500 obtainable through the exercise of options granted to Dr. Madri, which are not exercisable within 60 days of October 1, 2002.

(11)

Includes 52,389 shares of common stock, which may be acquired upon the exercise of options within 60 days of October 1, 2002. Excludes 30,611 shares obtainable through the exercise of options granted to Dr. Mojcik, which are not exercisable within 60 days of October 1, 2002.

(12)

Includes 11,167 shares of common stock which may be acquired upon the exercise of options within 60 days of October 1, 2002. Excludes 16,500 shares obtainable through the exercise of options granted to Dr. Link, which are not exercisable within 60 days of October 1, 2002.

(13)

Includes 26,874 shares of common stock which may be acquired on the exercise of options that are exercisable within 60 days of October 1, 2002. Excludes 44,126 shares obtainable through the exercise of options granted to Mr. Dubin, which are not exercisable within 60 days of October 1, 2002.

(14)

Includes 18,000 shares of common stock which may be acquired on the exercise of options that are exercisable within 60 days of October 1, 2002. Excludes 16,500 shares obtainable through the exercise of options granted to Mr. Jackson, which are not exercisable within 60 days of October 1, 2002.

(15)

Includes 18,000 shares of common stock which may be acquired on the exercise of options that are exercisable within 60 days of October 1, 2002. Excludes 16,500 shares obtainable through the exercise of options granted to Mr. Norby, which are not exercisable within 60 days of October 1, 2002

(16)

Includes 16,900 shares of common stock which may be acquired on the exercise of options that are exercisable within 60 days of October 1, 2001. Excludes 16,500 shares obtainable through the exercise of options granted to Mr. Parven, which are not exercisable within 60 days of October 1, 2002.

(17)

Consists of shares beneficially owned by Drs. Bell, Fried, Link, Madri, Mojcik, and Squinto and Messrs. Dubin, Jackson, Keiser, Norby and Parven, and certain other officers. Includes 1,422,860 shares of common stock, which may be acquired upon the exercise of options within 60 days of October 1, 2002.

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(1)

Reflects aggregate options outstanding and available for issuance, if applicable, under our 1992 Stock Option Plan, 1992 Stock Option Plan for Outside Directors, and 2000 Stock Option Plan.

(2)

Does not include 38,585 shares of common stock to be issued upon exercise of options granted under Prolifaron Inc. 1999 Long Term Incentive and Stock Option Plan with a vested average exercise price of $45.24 per share. The stock options granted under this plan were converted into options to acquire shares of our common stock in connection with our acquisition of Prolifaron in September 2000. No subsequent grants of options will be made under this plan.

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*

Previously filed

(1)

Incorporated by reference to our report on Form 8-K, filed on October 3, 2000.

(2)

Incorporated by reference to our Registration Statement on Form S-1 (Reg. No. 333-00202).

(3)

Incorporated by reference to our Quarterly Report on Form 10-Q for the quarter ended April 30, 2000.

(4)

Incorporated by reference to our Annual Report on Form 10-K for the fiscal year ended July 31, 2000.

(5)

Incorporated by reference to our Annual Report on Form 10-K for the fiscal year ended July 31, 1997.

(6)

Incorporated by reference to our Registration Statement on Form S-3 (Reg. No. 333-36738) filed on May 10, 2000.

(7)

Incorporated by reference to our Registration Statement on Form S-8 (Reg. No. 333-71879) filed on February 5, 1999.

(8)

Incorporated by reference to our Registration Statement on Form S-8 (Reg. No. 333-69478) filed on September 14, 2001.

(9)

Incorporated by reference to our Registration Statement on Form S-8 (Reg. No. 333-71985) filed on February 8, 1999.

(10)

Incorporated by reference to our Annual Report on Form 10-K for the fiscal year ended July 31, 1996.

(11)

Incorporated by reference to our Annual Report on Form 10-K for the fiscal year ended July 31, 1999.

(12)

Incorporated by reference to our Quarterly report Form 10-Q for the quarter ended January 31, 2002.

†

Confidential treatment was granted for portions of such document.

††

A request for confidential treatment was filed for certain portions of the indicated document. Confidential portions have been omitted and filed separately with the Commission as required by Rule 24b-2.

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(a)

Includes the noncash charge for IPRD of $21,000 and Cumulative Effect of Adoption of SAB 101 of $9,118.

(b)

Includes the noncash charges for IPRD of $1.21 and Cumulative Effect of Adoption of SAB 101 of $0.52.

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                                                                   EXHIBIT 10.24

                                                          CONFIDENTIAL TREATMENT




                           MEMORANDUM OF UNDERSTANDING

                Revised P&GP / Alexion Pexelizumab Collaboration

This Memorandum represents a summary of the Parties' interests in renegotiating
their current Collaboration and it is binding as set forth in the final
paragraph hereof.

OVERVIEW AND MANAGEMENT OF THE COLLABORATION

     Scope: P&GP and Alexion propose to revise the Collaboration Agreement (the
     "Collaboration Agreement") dated January 25, 1999 in accordance with this
     Memorandum. P&GP and Alexion agree to negotiate in good faith to restate
     the Collaboration Agreement (the "Restatement") in accordance with this
     Memorandum.

     Collaboration Agreement. Except as specifically set forth herein, all terms
     of the Collaboration Agreement shall continue with full force and effect
     following the execution and delivery of this Memorandum.

     Definitions. Capitalized terms used but not defined herein have the
     meanings set forth in the Collaboration Agreement.

     Decisions - R&D, Health Registrations and Supply Issues: Alexion and P&GP
     will have equal decision-making authority for all R&D, Health Registration
     and Product Supply/Process Development issues. Such issues will be
     addressed and resolved through the R&D Steering Committee. Either party may
     refer an issue for further review and resolution to the President of
     Alexion and the President of Procter & Gamble Pharmaceuticals (the
     "Presidents"). Action will be delayed until such meeting or discussion
     between the Presidents. If the Presidents cannot resolve the issue within
     [*****] business days of such reference (or longer period mutually agreed
     by the Presidents), the matter will be submitted to a neutral arbitrator
     (the "Neutral") within [*****]

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                                                                   EXHIBIT 10.24

     business days thereafter. Both Parties agree to select a Neutral with
     experience in the U.S. pharmaceutical industry and to use their best
     efforts promptly to cooperate with any investigations and deliberations of
     the Neutral. The Parties will present to the Neutral their respective
     issues with proposed solutions for the Neutral to make a determination. The
     Neutral's determination will be limited to either Party's solution. The
     Neutral's determination will be final and binding on the Parties. The fees
     and costs of the Neutral will be shared equally between the Parties. The
     Parties agree to identify and engage a mutually acceptable Neutral promptly
     after execution of the Restatement, to avoid delay in the event the
     Neutral's determinations become necessary.

     Decisions - Commercialization Issues: The Parties shall form a
     Commercialization Steering Team (the "CST"), that will analyze, discuss and
     agree on all commercialization strategies, plans and budgets for
     commercialization of the product in the U.S. This team will have equal
     membership from both P&GP and Alexion. The CST will establish an annual
     commercialization plan, which shall be binding on the Parties. The CST will
     resolve all commercialization issues, including but not limited to
     Marketing, Promotion, Labeling, Phase IIIb/IV studies, Scientific Exchange
     and Education. Either party may refer a commercialization issue for further
     review and resolution to the Presidents. Action will be delayed until such
     meeting or discussion between the Presidents. If the Presidents cannot
     resolve the issue within [*****] business days of such meeting or
     discussion, the matter will be resolved by [*****].

     The development and execution of all commercialization strategies and plans
     in the ROW will remain the sole responsibility of P&GP.

     Executional Responsibilities:

     The executional responsibility of each Party for clinical programs is
     outlined on Schedule I which is attached and incorporated herein. While an
     individual Party has lead executional responsibility, the Parties agree
     there will be no unilateral decision-making by either Party on any aspect
     of the clinical program's execution. Both Parties will as soon as practical
     but in no event later than within [*****], share all significant
     information relating to the development of pexelizumab received from any
     Third Party related to the project, including but not limited to, FDA,
     CROs, clinical sites, or suppliers, about the programs. All other
     information relating to the development

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                                                                   EXHIBIT 10.24

     of pexelizumab will be shared at weekly updates. Prior to meeting with any
     such Third Party regarding the development of pexelizumab, each Party will
     give the other Party adequate advance notice and full ability to
     meaningfully participate. Unless otherwise agreed by the Parties, the
     executional teams, including the Clinical Strategy Team and Clinical
     Execution Team, will meet at a minimum of every week to discuss issues,
     including but not limited to, any executional changes to the protocol or
     plan, the status on any budgetary or spending changes, the status on
     recruitment rates, IRB approvals, etc. When a study is unblinded, each
     Party will participate equally in developing a consistent interpretation of
     the data. A senior management team consisting of Vice Presidents or
     Directors with senior authority for a function, will meet quarterly to
     review, resolve issues as necessary and comment on the status of the
     various clinical and product supply/ process development executional teams,
     including but not limited to, spending versus budget and progress against
     project milestones.

     [*****] will have full responsibility for management of the preparation of
     the global marketing applications with input from [*****]. [*****] will
     lead interactions with FDA regarding the BLA preparation (e.g., pre-BLA
     meetings). [*****] will be responsible for supplying global modular
     documents with input from [*****] to use in completing the CMC section of
     the global marketing applications. [*****] will have full responsibility
     for preparation, content and maintenance of the Product's labeling, subject
     to [*****] prior review and opportunity to comment.

     Clinical Databases: Clinical databases for CABG and AMI will continue to
     use P&GP systems and specifications and remain under P&GP control and
     ownership, in accordance with the Collaboration Agreement. P&GP will give
     Alexion current access to all such databases. Both Parties must agree prior
     to granting access to any portion of the database to a Third Party. In the
     event P&GP exercises the Opt Out option and the Collaboration Agreement is
     terminated, P&GP will without further consideration promptly transfer
     ownership of such databases to Alexion, and will provide Alexion other
     access reasonably needed by Alexion, including but not limited to,
     introducing Alexion to database vendors that P&GP license from and
     providing Alexion licenses to P&GP owned software exclusively for use in
     connection with the CABG and AMI clinical database, so Alexion is able to
     assume control of and to exploit the databases to the same extent as P&GP
     had been capable of internally.

                                       3


                                                                   EXHIBIT 10.24

RESEARCH AND DEVELOPMENT PLAN

     U.S. R&D Funding: P&GP will continue to control AMI Phase II and fund all
     out-of-pocket costs and in-house FTE costs for work performed pursuant to
     the R&D Plan for the AMI Phase II program. Alexion and P&GP will each pay
     50% of all pre-agreed out-of-pocket costs to Third Parties for work
     performed pursuant to the R&D Plan for the AMI Phase III U.S. program and
     the CABG Phase III U.S. program, plus mutually agreed Alexion and P&GP FTE
     costs in connection therewith. Prior to commencement of a program an
     overall budget ("Budget") must be pre-agreed in writing by the Parties.
     This Budget will be updated no less than every 6 months and all changes
     must be agreed to in writing. Out-of-pocket costs include any mutually
     agreed-to payments to Third Parties. Studies conducted outside the United
     States that are used to support either Phase III U.S. program shall be
     considered U.S. program costs. Any expenses incurred by either Party that
     were not pre-agreed to in writing as part of the Budget process will be the
     sole responsibility of the Party that incurred the expense.

          CABG. Alexion agrees to pay the first 50% of the total pre-agreed
          estimated costs in respect of the CABG Phase III U.S. program (i.e.,
          $[*****]). For clarity, P&GP's previous expenditure for CABG Phase
          III, the amount of which will be agreed as set forth below, will not
          be counted as part of Alexion's first 50% of costs. Unless agreed
          otherwise by the Parties in writing as part of the establishment of
          the Budgets, Alexion will pay the first $[*****] of such costs, P&GP
          will pay the second $[*****] of such costs, and the Parties will
          simultaneously, evenly pay any additional mutually-agreed costs. Upon
          completion or jointly agreed termination of the CABG Phase III U.S.
          program, if either Party has paid more than the other Party in
          connection therewith, the Party having paid less will promptly make a
          reconciliation payment to the other Party, such that each party has
          paid 50% of the total of such mutually-agreed costs. Each Party
          acknowledges that the other has incurred costs directly related to the
          CABG Phase III program prior to execution of this Memorandum.
          Accordingly, each Party will be credited with having already spent
          such amounts in evening the total costs to be absorbed by the Parties.
          A full accounting will be completed upon signing this Memorandum to
          itemize the specific CABG Phase III costs incurred by the Parties as
          of that date.

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          AMI. Alexion and P&GP will determine a structure to result in their
          paying their respective 50% of AMI Phase III costs simultaneously.

          Clinical Supply Costs. All clinical supply costs incurred prior to
          initiation of the CABG Phase III program shall be expensed on
          initiation of the trial, and further such costs will be expensed when
          incurred.

     ROW R&D Funding: P&GP is free to re-use, outside the U.S., any data or
     information generated from any study performed for U.S. Health
     Registration, without incurring any additional expense. Alexion is free to
     use, within the U.S., any data or information generated by P&GP from any
     study performed solely for a ROW Health Registration, without incurring any
     additional expense. P&GP may elect to include ROW sites in U.S. led Phase
     IIIb and Phase IV studies. In the event ROW sites are included in such
     studies, P&GP will pay for the expenses specifically associated with
     patients enrolled solely for the ROW needs. If pre-agreed Phase IIIb and
     Phase IV studies are used in the U.S. and ROW for new marketing or labeling
     claims, P&GP will pay [*****] of the cost and Alexion will pay [*****]. All
     additional R&D expenses specifically and uniquely required for the Health
     Registration or commercialization of pexelizumab outside of the U.S. will
     be the responsibility of P&GP.

     P&GP OPT-OUT OPTION: P&GP may terminate ("Opt-Out") the Collaboration in
     its sole discretion by providing six months notice following [*****] and no
     later than the earlier of (i) 30 days after receipt of [*****] and (ii)
     [*****].

     In the event P&GP elects to exercise its Opt-Out option, P&GP has no
     responsibility for CABG Phase III expense other than (i) the mutually
     agreed expenses incurred prior to exercise of the Opt-Out that otherwise
     would be payable by P&GP pursuant to "CABG", above, and (ii) CABG Phase III
     amounts paid by P&GP prior to execution of this Memorandum. By way of
     example, if P&GP exercises the Opt-Out option and $[*****] has been
     expended on CABG Phase III, and it is determined that P&GP paid $[*****]
     prior to execution of this agreement in connection with CABG Phase III,
     Alexion would have paid $[*****] and P&GP [*****]. During the six month
     notice period, P&GP will continue to provide continuing executional support
     for AMI and CABG Phase

                                       5


                                                                   EXHIBIT 10.24

     III hereunder but will have no financial liability for any AMI or CABG
     Phase III expenses, other than in-house P&GP FTE costs, to be paid 100% by
     P&GP, provided such FTE costs and expenses are consistent with pre-agreed
     Budgets and provided the work will be transferred to Alexion as soon as
     practicable.

     In the event P&GP elects to exercise its Opt-Out option, Alexion agrees to
     purchase from P&GP all mutually pre-agreed pexelizumab related
     manufacturing assets at current book value and to reimburse P&GP for all
     [*****] including but not limited to, [*****]. Alexion will also agree to
     assume any mutually pre-agreed [*****] including, but not limited to,
     [*****]. All asset transfers, contract assignments, and payments must be
     complete prior to the end of the [*****] notice period. This paragraph
     shall apply only to [*****] of P&GP's assets, and commitments and fees, if
     within [*****] of P&GP's Opt-Out exercise Alexion certifies that it too
     [*****].

PRODUCT SUPPLY AND PROCESS DEVELOPMENT:

     PS/PDC. The Parties will form a Product Supply / Process Development
     Committee (PS/PDC) with equal representation from each Party. The PS/PDC
     will be sponsored by the R&D Steering Committee. The PS/PDC will analyze,
     discuss and agree on decisions related to process development, clinical and
     commercial product supply, including but not limited to, choice of
     supplier(s), capital expenditures and product development activities. The
     PS/PDC will be responsible for and have decision-making authority for
     process development and production of Product for the R&D Plan and for
     commercialization. If the PS/PDC cannot reach agreement on a product supply
     issue, either Party may refer the issue to the R&D Steering Committee. If
     the R&D Steering Committee does not reach agreement within five business
     days of the referral, the matter will be addressed through the R&D Steering
     Committee Dispute Resolution process established above. The PS/PDC will
     develop and agree in writing to a Process Development Plan ("PDP") and a
     Product Supply Sourcing Plan ("PSSP") for the U.S. P&GP and Alexion will
     jointly share project leadership for execution of the Product Supply
     Sourcing Plan, and P&GP will be the primary vendor contact to provide a
     single and focused point of contact to leverage existing relationships and
     corporate purchasing scale; Alexion will provide input on the vendor
     contacts on a co-equal basis. Alexion and P&GP will jointly share project
     leadership for process development. The process development execution will
     be conducted consistent with P&GP and Alexion

                                       6


                                                                   EXHIBIT 10.24

     requirements. Alexion will perform bulk drug development and
     characterization and P&GP will provide input on a co-equal basis. P&GP will
     take the lead on vialing and other supply chain activities and Alexion will
     provide input on a co-equal basis. All U.S. process development and product
     supply agreements will be mutually agreed. P&GP will be sole signatory on
     all process development and product supply agreements. Within [*****] of
     the PS/PDC agreeing upon a viable source of commercial supply for
     pexelizumab, the PS/PDC will agree to the Product Supply Sourcing Plan. The
     PSSP will include, among other items, detail on validation timing, launch
     readiness requirements and longer-term forecasted volumes.

     The Parties acknowledge that certain vendors may support supply for both
     the U.S. and ROW. In such cases, the PS/PDC will ensure that vendor costs
     for U.S. and ROW supply are equal on a unit basis.

     In the event that supplies are insufficient for worldwide demand forecasted
     as of launch, [*****] will be [*****]. P&GP will provide Alexion the ROW
     product sourcing plan for review and input. Following launch, if supply is
     insufficient to meet total demand, available supply will be allocated based
     on the past [*****] volume. In the event of a likely shortage of product in
     [*****], P&GP agrees not to [*****]. Unless otherwise agreed by the
     Parties, the PS/PDC will strive to meet these non-binding objectives of the
     PS/PDC that include but are not limited to: (i) the primary commercial
     source(s) of pexelizumab shall be validated in accordance with all relevant
     regulations [*****] before the currently anticipated first BLA filing date
     and (ii) [*****] of commercial supply shall be ready for sale before the
     currently anticipated United States launch date. Meeting these non-binding
     objectives will be balanced against technical and commercial feasibility
     and required investment.

     Capital. Capital expenditures will be [*****]. P&GP will purchase all
     capital as agreed to by the PS/PDC in the PSSP and all assets will be
     maintained on P&GP's ledgers. Until the first launch of pexelizumab,
     [*****] of the annual capital depreciation will be charged to Alexion.
     Following the first launch, depreciation will be charged to the [*****].
     Alexion will thereby be charged [*****]. Assets will be depreciated based
     on P&GP's corporate accounting policy, which includes a determination of
     useful life on an asset-by-asset basis. In the event that P&GP is required
     to write

                                       7


                                                                   EXHIBIT 10.24

     down pexelizumab assets due to project failure, etc. (not including assets
     related to [*****]), Alexion will reimburse P&GP for [*****] expense
     associated with the write down.

     Supplier Advances. Until the first launch of pexelizumab, all supplier
     advances that are required to be expensed due to cancellations (other than
     ROW cancellations), will be [*****] between the Parties. Following the
     first launch, all expensed supplier advances will be [*****].

     Expenses. All other outside expense pre-agreed in writing that is
     associated with process development and production, including but not
     limited to all validation and test run costs, will be [*****] insofar as
     the same are uniquely and specifically required to support production
     capacity for U.S. commercialization, including in-house FTE costs for
     process development and product supply work conducted under the R&D Plan. A
     process development and product supply Budget must be pre-agreed in writing
     by the Parties. This Budget must be established in conjunction with PS/PDC
     agreement to the Process Development Plan and Product Supply Sourcing Plan.
     This Budget will be updated no less than every 6 months and all changes
     must be agreed to in writing. Any expenses incurred by either Party that
     were not pre-agreed to in writing as part of the Budget process will be the
     sole responsibility of the Party that incurred the expense. Any expense
     that is uniquely and specifically required to support production capacity
     for ROW commercialization shall be borne by [*****] and not reimbursed by
     [*****], and if such expense supports both U.S. and ROW commercialization,
     P&GP will pay [*****] and Alexion will pay [*****] of the expense.

HEALTH REGISTRATIONS:

     Sponsorship. Within the U.S., Alexion will be the Sponsor of the IND for
     CABG and P&GP will be the Sponsor of the IND for AMI. Both Parties will
     jointly plan, prepare for, and participate in all FDA interactions. All
     meetings with FDA will be led by the Sponsor. The Parties agree to adhere
     to the protocol for involving each other as outlined in Schedule II, which
     is attached and hereby incorporated by reference. P&GP will sponsor the BLA
     and all subsequent sBLAs and be responsible for filing, prosecuting and all
     FDA interactions concerning the BLA or any subsequent sBLAs. In order for
     P&GP to prepare for filing the BLA, Alexion agrees to transfer the IND for
     CABG to P&GP no later than practically required before the expected filing
     of the BLA, but in no event later than the pre-BLA meeting. Outside of the
     U.S., P&GP will be the sponsor of all Health

                                       8


                                                                   EXHIBIT 10.24

     Registrations. In the event P&GP exercises the Opt Out option and the
     Collaboration is terminated, P&GP will without further consideration
     promptly transfer sponsorship of its INDs and BLAs throughout the world to
     Alexion or its nominated agent(s), and will provide Alexion access
     reasonably needed by Alexion to assume control of and to exploit such INDs
     and BLAs to the same extent as P&GP had been capable of internally.

     Funding. All mutually agreed out-of-pocket and in-house FTE costs
     associated with filing or maintaining the U.S. Health Registration will
     [*****]. All out of pocket and in-house FTE costs associated with filing or
     maintaining Health Registrations outside of the U.S. will be borne by P&GP.

MARKETING AND PROMOTION:

     Commercialization Costs. P&GP and Alexion agree to [*****] all mutually
     agreed out-of-pocket and FTE costs associated with the commercialization of
     the Product [*****]. [*****] shall be responsible for all such costs
     [*****]. The CST will establish an annual U.S. commercialization plan and
     Budget agreed to in writing on or before July 1 of each year. Any expenses
     incurred by either Party that were not pre-agreed to in writing as part of
     the Budget process will be the sole responsibility of the Party that
     incurred the expense. All mutually agreed out-of-pocket and internal
     Alexion and P&GP FTE U.S. costs shall include but are not limited to the
     following:

          1.   costs for marketing, market research, advertising, sampling, and
               promoting the Product, such as advertising agency fees,
               advertising development costs, sales materials, development
               costs, training materials and public communication costs, speaker
               programs and conferences and other scientific education and
               exchange program (SEEP) costs incurred prior to and following
               Product approval;
          2.   costs related to creating and distributing any communication
               notice mandated by a government authority (e.g. Dear Doctor
               letters);
          3.   costs associated with manufacturing, distributing and shipping
               the Product samples to Third Parties and the handling and
               disposing of return shipments;
          4.   costs associated with obtaining, maintaining or enforcing Product
               related trademarks and logos;

                                       9


                                                                   EXHIBIT 10.24

          5.   costs for Phase IIIb, Phase IV and grant studies mutually agreed
               by the parties;
          6.   epidemiological modeling and pharmacoeconomic study costs; and
          7.   costs associated with effecting any Product recall (i.e.,
               communication, shipping and reimbursement costs).

     [*****]

1.   P&GP will [*****]. P&GP will discuss all matters related to [*****] with
     Alexion and provide Alexion an opportunity to comment thereon; provided
     that the final decisions on all such matters shall be made by Procter &
     Gamble in its sole discretion. Alexion will be notified of and invited to
     all meetings [*****]. Each party will bear its own internal costs, and P&GP
     will bear all P&GP outside costs and expense [*****], in connection with
     [*****]. Alexion has the right [*****]. If [*****], P&GP and Alexion
     [*****]. [*****] agrees to grant [*****] a sublicense [*****] necessary to
     carry out the Agreement. [*****] shall reimburse [*****] all amounts
     [*****], except that (i) subject to Clause 2 below, [*****] shall be
     responsible for [*****] in respect of [*****] in the United States, [*****]
     and (ii) [*****] shall be responsible [*****] in respect of [*****] outside
     the United States. [*****] will not be entitled to amend or otherwise
     modify [*****] without the prior, written consent of [*****].


2.   Notwithstanding Clause 1 above, [*****] shall be responsible for [*****] of
     United States [*****] under the [*****] until the difference between the
     amount payable under this Clause 2 and the amount otherwise payable under
     Clause 1 above exceeds the lesser of (i) [*****] in respect of United
     States [*****] and (ii) [*****]. Thereafter, this Clause 2 shall no longer
     apply.

3.   The [*****] in the United States and outside the United States will be
     identical under [*****], and all [*****] shall be apportioned [*****]
     between [*****] in the United States and [*****] outside the United States,
     respectively.

4.   All other [*****] (other than as set forth in [*****] of the Collaboration
     Agreement) related to [*****] in the United States shall be handled
     pursuant to Section [*****] of the

                                       10


                                                                   EXHIBIT 10.24

     Collaboration Agreement (i.e., [*****] will [*****]). All other [*****]
     (other than as set forth in [*****]) related to [*****] Product outside the
     United States shall be handled pursuant to Section [*****] of the
     Collaboration Agreement (i.e., [*****] will [*****]).

5.   [*****]

6.   Example. Following is an example of the operation of this [*****]
     provision:

          Assuming:

               [*****]

               [*****]

               [*****]

               [*****]

               [*****]

          Then:

               [*****]

               [*****]

               [*****]

               [*****]

     Sales Efforts. It is expected that each Party [*****] selling efforts in
     the U.S., including but not limited to, the efforts of liaisons and
     hospital representatives as mutually agreed. The Parties will each pay
     their own sales force and liaison costs (salaries, benefits, autos, bonuses
     or other incentive program costs, etc.). In the event [*****] selling
     effort would not be possible, the Party assigned more than [*****] will be
     reimbursed for the extra costs borne by that Party.

     One year before launch of the Product, the Parties will enter into a
     Marketing Services Agreement (MSA). The MSA will describe but not be
     limited to, terms on budgeting, forecasting, co-promotion services
     (including requirements for accounting for requisite Details or other calls
     on target prescribers, coordination of sales effort, compliance with laws
     and applicable authorities,

                                       11


                                                                   EXHIBIT 10.24

     etc.), sales penalties, penalties for under performance, responsibilities
     and procedures for Product returns and recalls.

ROYALTIES AND MILESTONES:

     U.S. Contribution: Alexion shall receive [*****]% of U.S. Contribution
     (Contribution is defined as Net Sales minus COGS ) on sales of pexelizumab
     in the United States. Sections 8.2(a), 8.2(b) and 8.2(c) of the original
     Agreement are eliminated.

     ROW Return: Alexion will receive [*****]% of ROW Net Sales.

     Milestones: All milestones in the Collaboration Agreement are eliminated
     and replaced by the following non-refundable, non-creditable one-time
     milestone payments. Each of these milestones is contingent upon P&GP not
     having terminated the Collaboration prior to achievement of the milestone
     event.


  MILESTONE                                                                                       AMOUNT
  ---------                                                                                       ------
                                                                                             (U.S. $ Million)
                                                                                          
  PRE-HEALTH REGISTRATION EVENTS

  At initiation of dosing of CABG Phase III clinical trial program
  which the Research & Development Steering Committee agreed would
  constitute a pivotal trial for approval of a Product for a CABG
  Indication                                                                                      [*****]

  At initiation of dosing of AMI Phase III clinical trial program
  which the Research & Development Steering Committee agreed would
  constitute a pivotal trial for approval of a Product for an AMI
  Indication                                                                                      [*****]


                                       12


                                                                   EXHIBIT 10.24

                                                                                               
  U.S. HEALTH REGISTRATION EVENTS

  On FDA acceptance for filing of the first U.S. Health Registration of a Product for an
  AMI Indication                                                                                  [*****]

  On first U.S. Health Registration approval of a Product for a CABG Indication                   [*****]

  On first U.S. Health Registration approval of a Product for an AMI Indication                   [*****]

  FOREIGN HEALTH REGISTRATION EVENTS (European Union
  filing/approval means in any country of the European Union.)

  On first filing for European Union Health Registration of
  a Product for a CABG Indication                                                                 [*****]

  On first filing for European Union Health Registration of
  a Product for an AMI Indication                                                                 [*****]

  On first European Union Health Registration approval of a Product
  for a CABG Indication                                                                           [*****]

  On first European Union Health Registration approval of a Product
  for an AMI Indication                                                                           [*****]


MISCELLANEOUS

     FTE Funding. The cost of each internal FTE will be calculated at $[*****],
     multiplied by the percentage of such employee's time devoted to the
     Collaboration. The R&D Steering Committee will determine FTE effort of each
     Party in respect of R&D, Health Registration and Supply issues.

                                       13


                                                                   EXHIBIT 10.24

     The Parties will mutually agree on all other FTE efforts, and the
     categories of employee chargeable to the Collaboration.

     Term: The term of the Collaboration Agreement will continue in each country
     of the world until pexelizumab is no longer sold in such country.

     Termination by P&GP: In addition to both Parties rights to terminate under
     the original Agreement, as amended hereby, P&GP has the right to exercise
     the Opt-Out option.

     Publicity: The Parties will jointly prepare and agree upon the public
     announcement of execution of this Memorandum and the Restatement.
     Thereafter, each Party agrees to publish or otherwise disclose the
     material, non-public results of the R&D Plan or of development studies or
     of the commercialization plan (a "Disclosure") only upon prior written
     approval of the other Party, not to be unreasonably withheld or delayed. In
     the event either Party is aware of an upcoming Disclosure, the Party will
     strive to provide the other Party [*****] advance notice of the Disclosure
     and its content. If specific wording is not available at a minimum the
     Party proposing the Disclosure will provide the other Party information on
     the general content and key messages proposed. The Parties agree whenever
     possible to provide press releases containing any Disclosure [*****] prior
     to proposed release. Notwithstanding the foregoing, this restriction does
     not prohibit a party from making Disclosures required by, or highly
     advisable under, law or government regulation (as determined by opinion of
     counsel of the party proposing such Disclosure). If a Party decides, upon
     the advice of counsel that a Disclosure is required or highly advisable,
     the Party will, insofar as is reasonably practical, notify the other Party
     of the decision and provide the other Party an advance copy for review and
     comment.

     Indemnification: Section 12.1 (b), "Indemnification for Marketing", in the
     Collaboration Agreement remains in full force. Notwithstanding the above,
     P&GP will not indemnify and hold harmless Alexion from and against any
     losses to the extent due to Alexion's gross negligence or willful or
     intentional misconduct. In the event that the Collaboration is terminated,
     Alexion agrees to provide an indemnification to P&GP in respect of Product
     commercialized by Alexion after termination, consistent with
     "Indemnification for Marketing" Section 12.1(b) in the Collaboration
     Agreement.

                                       14


                                                                   EXHIBIT 10.24
CHANGE IN CONTROL

     1.   Change in Control. Except as set forth in this provision ("Change in
          Control"), neither Party's consent is necessary to a Change in Control
          of the other Party, and the Collaboration Agreement shall be binding
          upon and inure to the benefit of either Party's successors in interest
          following any such Change in Control transaction. Section 13.7(a), (b)
          13.9 (c) of the Collaboration Agreement are deleted.

     2.   Notice. At any time during the Term, either P&GP or Alexion (the
          "Acquired Party") may notify (the "Notice") the other Party (the
          "Continuing Party") that it is contemplating a Change of Control
          transaction with a Third Party Company. All information provided in
          the Notice and otherwise provided in connection with the proposed
          Change of Control shall be maintained by the Continuing Party in the
          strictest confidence, including the fact that a Change of Control has
          been discussed and the name of the relevant Third Party Company, and
          the Continuing Party will restrict knowledge of such matters only to
          those of its employees who have a need to know the same.

     3.   Valuation Election. Within [*****] following receipt of the Notice,
          the Continuing Party may elect in writing (the "Election") delivered
          to the Acquired Party to cause a valuation to be made of the Acquired
          Company's entire interest in the Collaboration Agreement (the
          "Acquired Company's Agreement Interest") and the Continuing Company's
          entire interest in the Collaboration (the "Continuing Company's
          Agreement Interest", and together with the Acquired Company's
          Agreement Interest, the "Agreement Interest(s)"). Failure of the
          Continuing Party to provide such notice shall constitute waiver of its
          rights under this provision ("Change in Control"), and consent for the
          Change in Control to occur.

     4.   Valuation Process. Within [*****] of receipt of the Election, the
          Acquired Party and the Continuing Party shall each retain an
          internationally recognized investment banking firm to determine the
          value of the Agreement Interests (the "Prices"). If either Party fails
          to deliver notice to the other Party of its selection of an investment
          banking firm within such period, the Price determinations shall be
          rendered by the single investment banking firm so selected. If the

                                       15


                                                                   EXHIBIT 10.24

          Continuing Party has elected to cause the valuation to be made, it
          shall pay all fees and expenses of the investment bank(s). The
          investment banking firms selected in accordance with the foregoing
          procedure shall each determine the values of the Agreement Interests
          and submit their determinations of such values to the Parties within
          seven days following their selection. The values of Alexion's
          Agreement Interest and P&GP's Agreement Interest will be determined as
          set forth in Clause 9 below. The Price of each Party's Agreement
          Interest shall be the sum of the relevant values determined by each
          firm therefor, divided by two; provided, however, that if there is
          more than a [*****] percent ([*****]%) difference between the two such
          values for either or both such Agreement Interests, then within
          [*****] of when they have determined such values, the first two firms
          shall select a third internationally recognized investment banking
          firm to determine the Price of the Agreement Interest(s) that diverged
          more than [*****] (which shall be determined by such firm [*****] of
          selection, and in no event be outside the range determined by the
          first two investment banking firms).

     5.   Put/Call Election. Within [*****] ([*****]) [*****] following
          determination of the Price, the Continuing Party will irrevocably
          elect to (i) allow the Change in Control to occur, (ii) require the
          Third Party Company to purchase the Continuing Party's Agreement
          Interest at the relevant price, (iii) purchase the Acquired Party's
          Agreement Interest at the relevant price.

     6.   Purchase Consummation. Any purchase and sale of an Agreement Interest
          effected pursuant to this provision ("Change in Control") shall be
          consummated at a closing at the offices of the Continuing Party on a
          business day within [*****] following the determination of the
          relevant Price upon at least [*****] notice by the Third Party Company
          to the other parties to the transaction; or the earliest time
          thereafter following receipt of necessary governmental or regulatory
          approvals with respect to such transaction and the Change in Control
          transaction contemplated by Clause 2 above. At such closing, the Third
          Party Company (or its designee) or the Continuing Party (or its
          designee), as the case may be, shall pay the relevant Price by
          certified check or wire transfer of funds. In no event will such
          purchase and sale of an Agreement Interest occur unless and until the
          Third Party Company identified under Clause 2 above consummates the
          Change in Control transaction with the Acquired Company contemplated
          by the Notice.

                                       16


                                                                   EXHIBIT 10.24

     7.   Purchase Documentation. Upon the closing of the transactions
          contemplated by Clause 6 above, the Parties and the Third Party
          Company shall execute such customary instruments of transfer, licenses
          and other agreements as are necessary to transfer all of the relevant
          Agreement Interest to assure that the party acquiring such interest
          shall be able to enjoy the benefits thereof. The Party whose Agreement
          Interest is acquired shall license or sublicense all of its
          intellectual property necessary for the manufacture, use or sale of
          Products in the Field, and the party acquiring such Agreement Interest
          shall assume all obligations, including payment obligations, to any
          Third Party from whom the party whose Agreement Interest is acquired
          licenses such intellectual property. All other necessary agreements
          (e.g., supply) will also be transferred; or if not transferable, the
          benefits thereof will otherwise be provided.

     8.   Third Party Company. "Third Party Company" shall mean, in the case of
          P&GP, the five companies listed by it on Schedule III (together with
          their majority owned, direct or indirect subsidiaries), and in the
          case of Alexion, the five companies listed by it on Schedule III
          (together with their majority owned, direct or indirect subsidiaries).
          Each Party shall supply its initial list to the other following
          execution and delivery of this Memorandum. Either Party may revise its
          list by written notice to the other delivered within [*****] on or
          after [*****] and [*****] during the Term. Within [*****] on or after
          [*****] and [*****] during the Term, Alexion agrees to provide P&GP a
          written reminder of P&GP's rights under this Section. Neither Party
          shall have the right to amend its list of 5 companies after the
          Acquired Party publicly announces, or confidentially notifies the
          Continuing Party, that it proposes a Change of Control transaction
          with a company that is not on the list.

     9.   Agreement Interests. The retained investment banks shall be instructed
          to value P&GP's Agreement Interest at the amount that, on the basis of
          market and other conditions prevailing at such time could reasonably
          be expected to be paid by a third party in an arm's-length transaction
          for [*****]. The retained investment banks shall be instructed to
          value Alexion's Agreement Interest at the amount that, on the basis of
          market and other conditions prevailing at such time is the difference
          between what could reasonably be expected to be paid by a third party
          in (i) an arm's-length transaction for [*****].

                                       17


                                                                   EXHIBIT 10.24

     10.  Closing Condition. Consummation of any Change In Control transaction
          will require that the Third Party Company agree to be bound by the
          terms of this provision ("Change in Control").

SUBSTANTIAL STOCK ACCUMULATION: Section 13.8 of the Collaboration Agreement
          applies only to accumulation in the equity of one Party hereto by a
          Third Party Company listed by the other Party hereto. Further, Section
          13.8 has no force or effect in regard to a Third Party following a
          Change of Control involving such Third Party.

EXECUTIONOF THIS MEMORANDUM OF UNDERSTANDING: Upon execution, the terms of this
          Memorandum will be in full force and effect. The Parties agree to
          diligently negotiate the terms of the Restatement. Prior to the
          Restatement being executed, in the event an issue is not addressed in
          this Memorandum but is in the Collaboration Agreement, the Parties
          will operate under the Collaboration Agreement on the issue. Prior to
          the Restatement being executed, the Parties agree Section 13.2 of the
          Collaboration Agreement, "Termination", remains in full force;
          provided, however, Section 13.2(a) of the Collaboration Agreement is
          deleted, and replaced by the following:"Procter & Gamble may terminate
          the Agreement upon six (6) months prior written notice to Alexion."

                                       18


                                                                   EXHIBIT 10.24

IN WITNESS WHEREOF, the Parties have signed this Memorandum as of
December 11, 2001.

ALEXION PHARMACEUTICALS, INC.

By: /s/ David W. Keiser
    ------------------------------------
   Name:
   Title:


PROCTER & GAMBLE PHARMACEUTICALS, INC.

By: /s/ Mark A. Collar
    ------------------------------------
   Name:
   Title:

                                       19


                                                                   EXHIBIT 10.24

                                   SCHEDULE 1

Executional Responsibilities:  Clinical Programs


- -------------------------------------------------------------------------------------------------------------
                                           CABG Phase III Program               AMI Phase III Program
                                           ----------------------               ---------------------
                                           ------------------------------------------------------------------
                Task                       R                    I                R                I
                                           -
- -------------------------------------------------------------------------------------------------------------
                                                                                  
           Project Leadership*               Shared           Shared           Shared           Shared
- -------------------------------------------------------------------------------------------------------------
Program Physician-Global/NA                [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
           Program Physician-              [*****]          [*****]         [*****]           [*****]
               Europe/ROW
- -------------------------------------------------------------------------------------------------------------
  CRO/Vendor Contracts, Bids and Scope     [*****]          [*****]         [*****]           [*****]
                 Changes
- -------------------------------------------------------------------------------------------------------------
       Site Contracts and Budgets          [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
Statistics and Biometrics including DSMB   [*****]          [*****]         [*****]           [*****]
                data flow
- -------------------------------------------------------------------------------------------------------------
               Clinops-NA                  [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
           CRO Interaction-NA              [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
  Vendor (e.g., Core Labs) Interaction     [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------

- -------------------------------------------------------------------------------------------------------------
           Site Interaction-NA             [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
           Clinops-Europe/ROW              [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
   CRO/Vendor Interaction- Europe/ROW      [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
      Site Interaction- Europe/ROW         [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
            Clinical Supplies              [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
               Clinical QA                 [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------

- -------------------------------------------------------------------------------------------------------------
        Pharmacovigilance NA ***           [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------


                                       20


                                                                   EXHIBIT 10.24

                                                                                  
- ------------------------------------------------------------------------------------------------------------
          Pharmacovigilance EU             [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
                PK and PD                  [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
            Pharmacoeconomics              [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
             Regulatory U.S.               [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
               Regulatory                  [*****]          [*****]         [*****]           [*****]
                   ROW
- -------------------------------------------------------------------------------------------------------------
        Clinical Data Management           [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
             Medical Writing               [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------
 Global Marketing Application Prep/Mgmt    [*****]          [*****]         [*****]           [*****]
- -------------------------------------------------------------------------------------------------------------


Abbreviations:  R = Responsibility; I = Input; P = P&GP: A = Alexion
*     Each company will appoint a project leader.
**    [*****] to have ability to set up initial site budget and contract in
      select cases
***   [*****] will have global responsibility for collecting and analyzing
      adverse events and will own the database. Sponsor will be responsible for
      filing the information with all regulatory authorities.

                                       21


                                                                   EXHIBIT 10.24

                                   SCHEDULE II

                                     [*****]

This document provides some expectations for involvement of the partner company
in FDA interactions (Alexion for BB IND 8651 [AMI] and P&GP for BB IND 6592
[CPB]). These expectations apply to all aspects of the project, including CMC.

The primary expectation is that the partner should be involved in all FDA
interactions where strategic and executional issues are discussed, unless both
partners have agreed in advance that it is not necessary.

Both partners should be involved in all scheduled FDA interactions, unless there
is an agreement in advance. When possible, the Regulatory Affairs Managers in
both companies should discuss and anticipate FDA interactions and reach
agreements about the need for involvement in advance of the FDA interaction. In
the event of an unscheduled FDA interaction, both partners agree to use best
efforts to involve the other partner. Unscheduled FDA interactions with a
Sponsor company should be communicated immediately to the non-Sponsor company.
Strategic decisions should not be made with FDA unless both companies are
present in the conversation, or an agreement to make such decisions has been
made by both companies in advance.

Partner involvement is not expected for administrative FDA interactions which
include discussions about scheduling of interactions, response to FDA requests
for additional copies of IND submissions, response to FDA requests for updates
on status of DSMB review, etc.

Nearly all FDA interactions should be easily managed in one of these ways. It is
recognized that in rare instances an "informal" interaction may occur where
FDA's willingness to share perspective could be hampered by a delay or by the
presence of additional participants in the interaction. In those rare instances
it is expected that the partner company will be contacted immediately following
the interaction and fully informed in writing as to the content of the
discussion. Strategic decisions should not be made with FDA unless both
companies are present in the conversation or an agreement to make such decisions
has been made by both companies in advance. It is also expected that every
effort will be made to keep

                                       22


                                                                   EXHIBIT 10.24

those advantageous informal discussions separate from the formal interactions
where partner presence is desired.

Each Party maintains the right to directly contact FDA, other regulatory
agencies, or other clinically responsible third parties (e.g., investigators,
IRBs, ) on any urgent safety or other medically significant concerns; provided,
however, that a non-Sponsor Party must first provide the Sponsor all information
regarding such concern and allow the Sponsor to be the Party that contacts the
FDA or such other agencies or third parties. If the Sponsor does not address the
non-Sponsor's concerns, and the non-Sponsor deems there is a regulatory or legal
requirement for reporting, the non-Sponsor reserves the right to directly
contact FDA, other regulatory agencies or other clinically responsible third
parties on the urgent safety or other medically significant concern. Prior to
making any third party contact the non-Sponsor will inform the Sponsor of its
decision.

                                       23


                                                                   EXHIBIT 10.24

                                  SCHEDULE III

                    CHANGE IN CONTROL - THIRD PARTY COMPANIES

- -------------------------------------------------------------------------------
Companies selected by Alexion:                Companies selected by P&GP:
- -------------------------------------------------------------------------------
1.[*****]                                     1. [*****]
- -------------------------------------------------------------------------------
2.[*****]                                     2. [*****]
- -------------------------------------------------------------------------------
3.[*****]                                     3. [*****]
- -------------------------------------------------------------------------------
4.[*****]                                     4. [*****]
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5.[*****]                                     5. [*****]
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[Each party to provide the other its list following execution and delivery of
this Memorandum]

                                       24

                                                                    Exhibit 21.1

                  SUBSIDIARIES OF ALEXION PHARMACEUTICALS, INC.


Columbus Farming Corporation (New York)
100% owned by Registrant


Alexion Antibody Technologies, Inc. (California)
100% owned by Registrant

                                                                    EXHIBIT 23.1

Consent of Independent Accountants

We hereby consent to the incorporation by reference in the Registration
Statements File numbers 333-19905, 333-24863, 333-29617, 333-36738, 333-41397,
333-47594, 333-47645, 333-52856, 333-52886, 333-59702, 333-69478, 333-71879 and
333-71985 of our report dated October 18, 2002 relating to the consolidated
financial statements of Alexion Pharmaceuticals, Inc., which appear in this Form
10-K.

/s/ PricewaterhouseCoopers LLP

Hartford, Connecticut
October 24, 2002

                                                                    EXHIBIT 99.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002



         In connection with the Annual Report of Alexion Pharmaceuticals, Inc.
(the "Company") on Form 10-K for the year ended July 31, 2002 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Leonard
Bell, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C.
section 1350, as adopted pursuant to section 906 of the Sarbanes-Oxley Act of
2002, that:

          (i) the Report fully complies with the requirements of section 13(a)
         or 15(d) of the Securities Exchange Act of 1934 and (ii) the
         information contained in the Report fairly presents, in all material
         respects, the financial condition and results of operations of the
         Company.

                                                     /s/ Leonard Bell
                                                     --------------------------
                                                     Leonard Bell, M.D.
                                                     Chief Executive Officer
                                                     October 24, 2002





                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002



         In connection with the Annual Report of Alexion Pharmaceuticals, Inc.
(the "Company") on Form 10-K for the year ended July 31, 2002 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, David
W. Keiser, President and Chief Operating Officer of the Company, certify,
pursuant to 18 U.S.C. section 1350, as adopted pursuant to section 906 of the
Sarbanes-Oxley Act of 2002, that:

          (i) the Report fully complies with the requirements of section 13(a)
         or 15(d) of the Securities Exchange Act of 1934 and (ii) the
         information contained in the Report fairly presents, in all material
         respects, the financial condition and results of operations of the
         Company.

                                           /s/ David W. Keiser
                                           ---------------------------
                                           David W. Keiser
                                           President and Chief Operating Officer
                                           October 24, 2002



45241228.1

                                                                    Exhibit 99.2


                                  RISK FACTORS

         The following risk factors should be carefully considered in evaluating
our Company and our business because these risk factors have a significant
impact on our business, operating results, financial condition, and cash flows.
If any of these risks actually occurs, our business, financial condition,
operating results and/or cash flows could be harmed.

If we continue to incur operating losses, we may be unable to continue our
operations.

         We have incurred losses since we started our company in January 1992.
As of July 31, 2002, we had an accumulated deficit of approximately $180.8
million. If we continue to incur operating losses and fail to become a
profitable company, we may be unable to continue our operations. Since we began
our business, we have focused on research and development of product candidates.
We have no products that are available for sale and do not know when we will
have products available for sale, if ever. We expect to continue to operate at a
net loss for at least the next several years as we continue our research and
development efforts, continue to conduct clinical trials and develop
manufacturing, sales, marketing and distribution capabilities. Our future
profitability depends on our receiving regulatory approval of our product
candidates and our ability to successfully manufacture and market approved
drugs. The extent and the timing of our future losses and our profitability, if
we are ever profitable, are highly uncertain.

If we do not obtain regulatory approval for our drug products, we will not be
able to sell our drug products.

         We cannot sell or market our drugs without regulatory approval. If we
do not obtain regulatory approval for our products, the value of our company and
our results of operations will be harmed. In the United States, we must obtain
approval from the U.S. Food and Drug Administration, or FDA, for each drug that
we intend to sell. Obtaining FDA approval is typically a lengthy and expensive
process, and approval is highly uncertain. Foreign governments also regulate
drugs distributed outside the United States, whose approval can also be lengthy,
expensive and highly uncertain. None of our product candidates has received
regulatory approval to be marketed and sold in the United States or any other
country. We may not receive regulatory approval of any of our product
candidates, if ever, for at least the next several years.

If our drug trials are delayed or achieve unfavorable results, we will have to
delay or may be unable to obtain regulatory approval for our products.

         We must conduct extensive testing of our product candidates before we
can obtain regulatory approval for our products. We need to conduct both
preclinical animal testing and clinical trials. These tests and trials may not
achieve favorable results. We would need to reevaluate any drug that did not
test favorably and either alter the study, the drug or the dose and perform
additional or repeat tests, or abandon the drug development project. In those
circumstances, we would not be able to obtain regulatory approval on a timely
basis, if ever. Even if approval is granted, the approval may require
limitations on the indicated uses for which the drug may be marketed.

         We have announced the completion of a Phase IIb trial of pexelizumab,
one of our two lead antibody product candidates, for the treatment of
complications in patients after cardiopulmonary bypass surgery, including the
reduction of the frequency and severity of myocardial infarctions, or heart
attacks and frequency of death. The primary therapeutic exploratory pre-set goal
of the trial, referred to as the primary endpoint, was not achieved. However, in
the pre-specified population that included approximately 90% of the patient
population, the 800 patients who had coronary artery bypass graft surgery
without valve surgery, those that received pexelizumab at the highest dose level
experienced a significant reduction in larger post-surgical heart attacks. Based
on these results, in January 2002, we commenced enrollment of a pivotal Phase
III clinical trial of pexelizumab in approximately 3,000 patients undergoing
coronary artery bypass graft surgery with cardiopulmonary bypass operations. The
Phase III trial will assess the safety and efficacy of pexelizumab in reducing
the combined incidence of death or myocardial infarction in this patient
population. We cannot assure you that this trial will be successful or that any
of the endpoints of the trial will be achieved.




                                       1


                                                                    Exhibit 99.2

         We have also announced the completion of a Phase II trial of
eculizumab, our other lead antibody product candidate, for the treatment of
rheumatoid arthritis. The primary endpoint, or therapeutic pre-set goal, for
this trial was met by the group of patients who received the mid-level dosing
regimen of eculizumab. Patients who received higher or lower doses of eculizumab
in the clinical trial did not achieve the primary endpoint.

          Completion of these and other trials does not guarantee that we will
initiate additional trials for our product candidates, that if the trials are
initiated what the scope and phase of the trial will be or that they will be
completed, or that if the trials are completed, the results will provide a
sufficient basis to proceed with further trials or to apply for or receive
regulatory approvals or to commercialize products. Results of trials could be
inconclusive, requiring additional or repeat trials.

         There are many reasons why drug testing could be delayed or terminated.
For human trials, patients must be recruited and each product candidate must be
tested at various doses and formulations for each clinical indication. Also, to
ensure safety and effectiveness, the effect of drugs often must be studied over
a long period of time, especially for the chronic diseases that we are studying.
Unfavorable results or insufficient patient enrollment in our clinical trials
could delay or cause us to abandon a product development program.

         Additional factors that can cause delay or termination of our clinical
trials include:

         . slow patient enrollment;

         . long treatment time required to demonstrate effectiveness;

         . lack of sufficient supplies of the product candidate;

         . adverse medical events or side effects in treated patients;

         . lack of effectiveness of the product candidate being tested; and

         . lack of sufficient funds.

We may expand our business through new acquisitions that could disrupt our
business and harm our financial condition.

         Our business strategy includes expanding our products and capabilities,
and we may seek acquisitions to do so. Acquisitions involve numerous risks,
including:

         . substantial cash expenditures;

         . potentially dilutive issuance of equity securities;

         . incurrence of debt and contingent liabilities, some of which may be
           difficult or impossible to identify at the time of acquisition;

         . difficulties in assimilating the operations of the acquired
           companies;

         . diverting our management's attention away from other business
           concerns;

         . risks of entering markets in which we have limited or no direct
           experience; and

         . the potential loss of our key employees or key employees of the
           acquired companies.

         We cannot assure you that any acquisition will result in long-term
benefits to us. We may incorrectly judge the value or worth of an acquired
company or business. In addition, our future success would depend in part on our
ability to manage the rapid growth associated with some of these acquisitions.
We cannot assure you that we will be able to make the combination of our
business with that of acquired businesses or companies work or be successful.
Furthermore, the development or expansion of our business or any acquired
business or companies may require a substantial capital investment by us. We may
not have these necessary funds nor may they be readily available to us on
acceptable terms or at all. We may also seek to raise funds by selling shares of
our stock, which could dilute your ownership interest in our company.




                                       2


                                                                    Exhibit 99.2

         On September 22, 2000, we purchased all of the capital stock and other
outstanding securities of Prolifaron, Inc., a privately held biopharmaceutical
company that is developing therapeutic antibodies addressing multiple diseases,
including cancer, for approximately 400,000 shares of our outstanding capital
stock. The business of Prolifaron, now our wholly-owned subsidiary, Alexion
Antibody Technologies, Inc., or AAT, is subject to many of the same risks that
our business is subject to. We cannot assure you that AAT will successfully
develop any products or that we will realize any benefits from the acquisition
of Prolifaron

If we fail to obtain the capital necessary to fund our operations, we will be
unable to continue or complete our product development.

         We believe we have sufficient capital to fund our operations and
product development for at least twenty-four months. We may need to raise
additional capital after that time to complete the development and
commercialization of our product candidates. Additional financing could take the
form of public or private debt or equity offerings, equity line facilities, bank
loans collaborative research and development arrangements with corporate
partners and/or the sale or licensing of some of our property. The amount of
capital we may need depends on many factors, including:

         . the existence, terms and status of collaborative arrangements and
           strategic partnerships, such as our collaboration with Procter &
           Gamble;

         . the progress, timing and scope of our research and development
           programs;

         . the progress, timing and scope of our preclinical studies and
           clinical trials;

         . the time and cost necessary to obtain regulatory approvals;

         . the time and cost necessary to further develop manufacturing
           processes, arrange for contract manufacturing or build manufacturing
           facilities and obtain the necessary regulatory approvals for those
           facilities;

         . the time and cost necessary to develop sales, marketing and
           distribution capabilities;

         . the cost necessary to sell, market and distribute our products, if
           any are approved;

         . changes in applicable governmental regulatory policies; and

         . any new collaborative, licensing and other commercial relationships
           that we may establish.

         We may not get funding when we need it or funding may only be available
on unfavorable terms. If we cannot raise adequate funds to satisfy our capital
requirements, we may have to delay, scale-back or eliminate our research and
development activities or future operations. We might have to license our
technology to others. This could result in sharing revenues that we might
otherwise retain for ourselves. Any of these actions may harm our business.

If our collaboration with Procter & Gamble is terminated or Procter & Gamble
reduces its commitment to our collaboration, our ability to commercialize
pexelizumab in the time expected, or at all, and our business would be harmed.

         We rely heavily on Procter & Gamble to perform development, obtain
commercial manufacturing, and provide sales and marketing for pexelizumab. While
we cannot assure you that pexelizumab will ever be successfully developed and
commercialized if Procter & Gamble does not perform its obligations in a timely
manner, or at all, our ability to commercialize pexelizumab will be
significantly adversely affected. We rely on Procter & Gamble, or P&G, to
provide funding and additional resources for the development and
commercialization of pexelizumab. These include funds and resources for:

         . clinical development and clinical and commercial manufacturing;

         . obtaining regulatory approvals; and

         . sales, marketing and distribution efforts worldwide.







                                       3


                                                                    Exhibit 99.2

         Prior to December 2001, Procter & Gamble was generally funding all
clinical development and manufacturing costs for pexelizumab. In December 2001,
we and P&G entered into a binding memorandum of understanding, or MOU, pursuant
to which we and P&G revised our collaboration. Per the MOU, our revised
collaboration provides for us and P&G to each incur approximately 50% of all
Phase III clinical trial, product development and manufacturing, and
commercialization costs necessary for the potential approval and marketing of
pexelizumab in the U.S. Procter & Gamble agreed to retain responsibility and
costs for future development and commercialization outside the U.S.
Additionally, as part of the MOU, we will receive milestone payments for
achieving specified development steps, regulatory filings and approvals, but
will not receive previously agreed sales milestones and will generally forego
further research and development support payments from P&G.

         P&G has the right to terminate the collaboration at any time.
Termination of our agreement with Procter & Gamble would cause significant
delays in the development of pexelizumab and result in additional development
costs. If we were to continue development of pexelizumab, we would need to fund
the development and commercialization of pexelizumab on our own or identify a
new development partner. We cannot guarantee that Procter & Gamble will devote
the resources necessary to successfully develop and commercialize pexelizumab in
a timely manner, if at all. Furthermore, Procter & Gamble may devote the
necessary resources, but we may still not successfully develop and commercialize
pexelizumab. We might also have to repeat testing already completed with Procter
& Gamble.

If we are unable to engage and retain third-party collaborators, our research
and development efforts may be delayed.

         We depend upon third-party collaborators to assist us in the
development of our product candidates. If any of our existing collaborators
breaches or terminates its agreement with us or does not perform its development
work under an agreement in a timely manner or at all, we would experience
significant delays in the development or commercialization of our product
candidates. We would also experience significant delays if we could not engage
additional collaborators when required. In either event, we would be required to
devote additional funds or other resources to these activities or to terminate
them. This would divert funds or other resources from other parts of our
business.

         We cannot assure you that:

         . current collaboration arrangements will be continued in their
           current form;

         . we will be able to negotiate acceptable collaborative agreements to
           develop or commercialize our product candidates;

         . any arrangements with third parties will be successful; or

         . current or potential collaborators will not pursue treatments for
           other diseases or seek other ways of developing treatments for our
           disease targets.

If the trading price of our common stock continues to fluctuate in a wide range,
our stockholders will suffer considerable uncertainty with respect to an
investment in our stock.

         The trading price of our common stock has been volatile and may
continue to be volatile in the future. Factors such as announcements of
fluctuations in our or our competitors' operating results, fluctuations in the
trading prices or business prospects of our competitors and collaborators,
including, but not limited to Procter & Gamble, changes in our prospects, and
market conditions for biotechnology stocks in general could have a significant
impact on the future trading prices of our common stock and our outstanding
notes. In particular, the trading price of the common stock of many
biotechnology companies, including ours, has experienced extreme price and
volume fluctuations, which have at times been unrelated to the operating
performance of the companies whose stocks were affected. This is due to several
factors, including general market conditions, the announcement of the results of
our clinical trials or product development and the results of our attempts to
obtain FDA approval for our products. In particular, since August 1, 2001, the
sales price of our common stock has ranged from a low of $9.58 per share to a
high of $26.69 per share and since August 1, 1999, the sales price of our common
stock has ranged from a low of $10.00 per share to a high of $119.88 per share.
While we cannot predict our future performance, if




                                       4



                                                                    Exhibit 99.2



our stock continues to fluctuate in a wide range, an investment in our stock or
our outstanding notes may result in considerable uncertainty for an investor.

If we cannot protect the confidentiality and proprietary nature of our trade
secrets, our business and competitive position will be harmed.

         Our business requires using sensitive technology, techniques and
proprietary compounds that we protect as trade secrets. However, since we are a
small company, we also rely heavily on collaboration with suppliers, outside
scientists and other drug companies. Collaboration presents a strong risk of
exposing our trade secrets. If our trade secrets were exposed, it would help our
competitors and adversely affect our business prospects.

         In order to protect our drugs and technology more effectively, we need
to obtain patents covering the drugs and technologies we develop. We may obtain
patents through ownership or license. Our drugs are expensive and time-consuming
to test and develop. Without patent protection, competitors may copy our
methods, or the chemical structure or other aspects of our drugs. Even if we
obtain patents, the patents may not be broad enough to protect our drugs from
copycat products.

If we are found to be infringing on patents owned by others, we may be forced to
obtain a license to continue the sale or development of our drugs and/or pay
damages. If we cannot obtain a license, we may be prevented from the sale or
development of our drugs.

         Parts of our technology, techniques and proprietary compounds and
potential drug candidates may conflict with patents owned by or granted to
others. If we cannot resolve these conflicts, we may be liable for damages, be
required to obtain costly licenses or be stopped from manufacturing, using or
selling our products or conducting other activities. For example, we are aware
of broad patents owned by others relating to the manufacture, use and sale of
recombinant humanized antibodies, recombinant humanized single chain antibodies,
recombinant human antibodies, recombinant human single chain antibodies, and
genetically engineered animals. Many of our product candidates are genetically
engineered antibodies, including recombinant humanized antibodies, recombinant
humanized single chain antibodies, recombinant human antibodies, and recombinant
human single chain antibodies, and other products are tissues from genetically
engineered animals.

         We have received notices from the owners of some of these patents
claiming that their patents may be relevant to the development, manufacture or
sale of some of our drug candidates. In response to some of these notices, we
have obtained licenses, or expect to obtain licenses. However, with regard to
other patents, we have either determined in our judgment that:

         . our products do not infringe the patents;

         . we do not believe the patents are valid; or

         . we have identified and are testing various modifications that we
           believe should not infringe the patents and which should permit
           commercialization of our product candidates.

         Any patent holders could sue us for damages and seek to prevent us from
manufacturing, selling or developing our drugs. Legal disputes can be costly and
time consuming to defend. If any of these actions are successful, we could be
required to pay damages or to obtain a license to sell or develop our drugs. A
required license may not be available on acceptable terms, if at all.

If the testing or use of our products harms people, we could be subject to
costly and damaging product liability claims.

         The testing, manufacturing, marketing and sale of drugs for use in
humans exposes us to product liability risks. Side effects and other problems
from using our products could give rise to product liability claims against us.
We might have to recall our products, if any, from the marketplace. Some of
these risks are unknown at this time. For example, little is known about the
potential long-term health risks of transplanting pig tissue into humans, a goal
of our UniGraft product development program. Use of C5 Inhibitors, such as
pexelizumab and eculizumab, is associated with an increased risk for infection
with Neisseria bacteria. Serious cases of Neisseria infection can result in
brain damage, loss of limbs or parts of limbs, kidney failure, or death.




                                       5


                                                                    Exhibit 99.2

         In addition, we may be sued by people who participate in our trials. A
number of patients who participate in such trials are already very ill when they
enter the trial. Any informed consents or waivers obtained from people who sign
up for our trials may not protect us from liability or litigation. Our product
liability insurance may not cover all potential liabilities or may not
completely cover any covered liabilities. Moreover, we may not be able to
maintain our insurance on acceptable terms. In addition, negative publicity
relating to a product liability claim may make it more difficult, or impossible,
for us to recruit patients for our clinical trials or to market and sell our
products. As a result of these factors, a product liability claim, even if
successfully defended, could have a material adverse effect on our business,
financial condition or results of operations.

If we cannot manufacture our drug candidates in sufficient amounts at acceptable
costs and on a timely basis, we may be unable to have the necessary materials
for product testing, and later for potential sale in the market. Either event
would harm our business.

         For our drug trials, we need to produce sufficient amounts of product
for testing. Our small manufacturing plant cannot manufacture enough of our
product candidates for later stage clinical development. In addition, we do not
have the capacity to produce more than one product candidate at a time. We
depend on a few outside suppliers for manufacturing. If we experience
interruptions in the manufacture of our products for testing, our drug
development efforts will be delayed. If any of our outside manufacturers stops
manufacturing our products or reduces the amount manufactured, we will need to
find other alternatives. If we are unable to find an acceptable outside
manufacturer on reasonable terms, we will have to divert our own resources to
manufacturing which may not be sufficient to produce the necessary quantity or
quality of product. As a result, our ability to conduct testing would be
materially adversely affected. Submission of products and new development
programs for regulatory approval would be delayed. Our competitive position and
our prospects for achieving profitability could be materially and adversely
affected.

         Manufacture of drug products is highly regulated by the FDA and other
domestic and foreign authorities. We cannot assure you that we or our
third-party collaborators will successfully comply with all of those
regulations, which would have a materially adverse effect on our business.

         We have no experience or capacity for manufacturing drug products in
volumes that would be necessary to support commercial sales. If we are unable to
establish and maintain commercial scale manufacturing within our planned time
and cost parameters, sales of our products and our financial performance would
be adversely affected.

         Other than our agreement with Procter & Gamble to develop and
commercialize pexelizumab, we have no arrangements to manufacture our products
on a commercial basis. Currently, we are relying on Procter & Gamble to retain
appropriate commercial manufacturing for pexelizumab through one or more
third-party manufacturers. The failure of Procter & Gamble to obtain appropriate
commercial manufacturing for pexelizumab on a timely basis, or at all, may
prevent or impede the commercialization of pexelizumab. We have not proceeded
far enough in negotiations with any other potential partner to be certain of the
cost of a commercial manufacturing arrangement for our potential products nor
have we explored the cost or time required to establish our own commercial
manufacturing facility. We are aware however, that due to the nature of the
current market for third-party commercial manufacturing arrangements, many
arrangements would require substantial penalty payments by us if we were not to
use the manufacturing capacity contracted for. The payment of a substantial
penalty would harm our financial condition.

If we are unable to establish sales, marketing and distribution capabilities, or
to enter into agreements with third parties to do so, we will be unable to
successfully market and sell future drug products.

         We have no sales or distribution personnel or capabilities, and have
only recently begun to develop marketing personnel and capabilities. If we are
unable to establish those capabilities, either by developing our own
capabilities or entering into agreements with others, we will not be able to
successfully sell our products. In that event, we will not be able to generate
significant revenues. We cannot guarantee that we will be able to hire the
qualified sales and marketing personnel we need. We may not be able to enter
into any marketing or distribution agreements with third-party providers on
acceptable terms, if at all. Currently, we are relying on Procter & Gamble for
sales, marketing and distribution of pexelizumab. Procter & Gamble, or any
future third-party collaborators, may not succeed at selling, marketing or
distributing any of our future drug products.




                                       6


                                                                    Exhibit 99.2

If we are unable to obtain reimbursement from government health administration
authorities, private health insurers and other organizations for our future
products, our products may be too costly for regular use and our ability to
generate revenues would be harmed.

         Our products, once commercialized, like similar products in the market
place, may be significantly more expensive than traditional drug treatments. Our
future revenues and profitability will be adversely affected if we cannot depend
on governmental and private third-party payors to defray the cost of our
products to the consumer. If these entities refuse to provide reimbursement with
respect to our products or determine to provide a low level of reimbursement,
our products may be too costly for general use. Our profitability may be
adversely impacted if we choose to offer our products at a reduced price. Any
limitation on the use of our products or any decrease on the price of our
products without a corresponding decrease in expenses will have a material
adverse effect on our ability to achieve profitability.

Even if we successfully develop our products for transplanting animal cells into
humans, this technology may not be accepted by the market due to medical
concerns or unanticipated regulation.

         Our program for the development of animal cells for transplantation
into humans may never result in any therapeutic products. This technology is
subject to extensive clinical testing and we are not aware of any such
technology that has been approved for sale by the FDA or comparable foreign
regulatory authorities. Even if we succeed in developing these products, our
products may not be widely accepted by the medical community or third-party
payors until more facts are established and ethical consensus is reached
regarding the use of animal cells. In addition, concerns relating to the risk of
introducing animal viruses to infect the human species through the
transplantation process may also create additional regulatory hurdles for FDA
approval. If accepted, the degree of acceptance may limit the size of the market
for our products. Moreover, due to the controversial nature of transplantation
of animal cells into humans generally, market prices for our securities may be
subject to increased volatility.

If our competitors get to the marketplace before we do with better or cheaper
drugs, our drugs may not be profitable to sell or to continue to develop.

         Each of Avant Immunotherapeutics, Inc, Millennium Pharmaceuticals,
Inc., Tanox, Inc., Abbott Laboratories, Baxter International Inc., Gliatech
Inc., Neurogen Corporation, and Biocryst Pharmaceuticals have publicly announced
their intentions to develop drugs which target the inflammatory effects of
complement in the immune system. We are also aware that Pfizer, Inc.,
GlaxoSmithKline plc and Merck & Co., Inc. are also attempting to develop
complement inhibitor therapies. Each of Cambridge Antibody Technology Group plc,
MorphoSys AG and Dyax Corporation has publicly announced intentions to develop
therapeutic human antibodies from libraries of human antibody genes.
Additionally, each of Abgenix Inc. and Medarex, Inc. has publicly announced
intentions to develop therapeutic human antibodies from mice that have been bred
to include some human antibody genes. These and other pharmaceutical companies,
many of which have significantly greater resources than we, may develop,
manufacture and market better or cheaper drugs than our product candidates. They
may establish themselves in the marketplace before we are able to even finish
our clinical trials. Other pharmaceutical companies also compete with us to
attract academic research institutions as drug development partners, including
for licensing these institutions' proprietary technology. If our competitors
successfully enter into such arrangements with academic institutions, we will be
precluded from pursuing those specific unique opportunities and may not be able
to find equivalent opportunities elsewhere.

If we fail to recruit and retain personnel, our research and product development
programs may be delayed.

         We are highly dependent upon the efforts of our senior management and
scientific personnel, particularly, Leonard Bell, M.D., our Chief Executive
Officer and Director, David W. Keiser, our President, Chief Operating Officer
and Director, and Stephen P. Squinto, Ph.D., our Executive Vice President and
Head of Research. There is intense competition in the biotechnology industry for
qualified scientific and technical personnel. Since our business is very
science-oriented and specialized, we need to continue to attract and retain such
people. We may not be able to continue to attract and retain the qualified
personnel necessary for developing our business. We have a key man insurance
policy for Dr. Bell and we have an employment agreement with Dr. Bell. We are
currently negotiating new employment agreements with Mr. Keiser and Dr. Squinto.
We cannot assure you that we will be





                                       7



                                                                    Exhibit 99.2



able to negotiate employment agreements with Mr. Keiser and Dr. Squinto or what
the terms of those agreements would be. To our knowledge, none of our key
personnel is planning to retire or is nearing retirement age. Further, to our
knowledge, there is no tension between any of our key personnel and the Board.
If we lose the services of our management and scientific personnel or fail to
recruit other scientific and technical personnel, our research and product
development programs would be significantly and detrimentally affected.

         In particular, we highly value the services of Dr. Leonard Bell, our
Chief Executive Officer. The loss of his services could materially and adversely
affect our ability to achieve our development objectives.

The conviction of our former independent public accountants, Arthur Andersen
LLP, on federal obstruction of justice charges may adversely affect Arthur
Andersen LLP's ability to satisfy any claims arising from the provision of
auditing services to us and may impede our access to the capital markets.

         On March 14, 2002, our previous independent public accounting firm,
Arthur Andersen LLP, was indicted on federal obstruction of justice charges
arising from the federal government's investigation of Enron Corp. On June 15,
2002, a jury returned with a guilty verdict against Arthur Andersen LLP
following a trial. As a public company, we are required to file with the U.S.
Securities and Exchange Commission, or SEC, periodic financial statements
audited or reviewed by an independent public accountant. On May 31, 2002, we
dismissed Arthur Andersen LLP as our independent public accountants, and engaged
a new independent public accounting firm to audit our financial statements for
fiscal 2002. It may be impossible for you to obtain recoveries from Arthur
Andersen LLP with respect to its audits of our financial statements as a result
of its conviction in the Enron matter. In addition, Arthur Andersen LLP has not
performed any procedures in connection with our Annual Report on Form 10-K for
the fiscal year ended July 31, 2002 and has not consented to the incorporation
by reference of its reports in our Annual Report on Form 10-K for the fiscal
year ended July 31, 2002, and therefore, you will not be able to recover against
Arthur Andersen LLP for any untrue statements of material fact contained in the
financial statements audited by Arthur Andersen LLP or any omissions to state a
material fact required to be stated therein.

         Should we seek access to the public capital markets, the SEC rules will
require us to include or incorporate by reference in any prospectus three years
of audited financial statements. The SEC's current rules would require us to
present audited financial statements for one or more fiscal years audited by
Arthur Andersen LLP and obtain their consent and representations until our
audited financial statements for the fiscal year ending July 31, 2004 become
available in the first quarter ended October 31, 2004. We expect that we would
not be able to obtain the necessary consent and representations from Arthur
Andersen LLP who have ceased operations. As a result, we may not be able to
satisfy the SEC requirements for a registration statement or for our periodic
reports. Even if the SEC decides to accept financial statements previously
audited by Arthur Andersen LLP, but without their current consent and
representations, those financial statements would not provide us and any
underwriters with the same level of protection under current securities laws as
would otherwise be the case. In either of these situations, our access to the
capital markets would be impaired unless PricewaterhouseCoopers LLP, our current
independent public accounting firm, or another independent public accounting
firm, is able to audit the financial statements originally audited by Arthur
Andersen LLP. Any delay or inability to access the public capital markets caused
by these circumstances could have a material adverse effect on our business,
profitability and growth prospects.



                                       8

                                                                    EXHIBIT 99.3

THE FOLLOWING REPORT IS A COPY OF A REPORT PREVIOUSLY ISSUED BY ARTHUR ANDERSEN
LLP AND HAS NOT BEEN REISSUED BY ARTHUR ANDERSEN LLP. THE COMPANY IS UNABLE TO
OBTAIN A REISSUED REPORT OR CONSENT TO INCORPORATION BY REFERENCE OF ARTHUR
ANDERSEN LLP'S REPORT FROM ARTHUR ANDERSEN LLP BECAUSE ARTHUR ANDERSEN LLP HAS
CEASED OPERATIONS.

                    Report of Independent Public Accountants

To the Board of Directors and Stockholders of
Alexion Pharmaceuticals, Inc.:

We have audited the accompanying consolidated balance sheets of Alexion
Pharmaceuticals, Inc. (a Delaware corporation) and subsidiaries (collectively,
the Company) as of July 31, 2001 and 2000, and the related consolidated
statements of operations, stockholders' equity and comprehensive loss, and cash
flows for each of the three years in the period ended July 31, 2001. These
consolidated financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these consolidated
financial statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States. Those standards require that we plan and perform the audit
to obtain reasonable assurance about whether the financial statements are free
of material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant estimates
made by management, as well as evaluating the overall financial statement
presentation. We believe that our audits provide a reasonable basis for our
opinion.

In our opinion, the consolidated financial statements referred to above present
fairly, in all material respects, the consolidated financial position of Alexion
Pharmaceuticals, Inc. and subsidiaries as of July 31, 2001 and 2000, and the
consolidated results of their operations and their cash flows for each of the
three years in the period ended July 31, 2001, in conformity with accounting
principles generally accepted in the United States.

As further discussed in Note 2 to the consolidated financial statements, during
the year ended July 31, 2001, the Company changed its method of revenue
recognition relating to non-refundable upfront licensing fees in accordance with
Staff Accounting Bulletin No. 101.

                                                         /s/ Arthur Andersen LLP

Hartford, Connecticut
August 31, 2001