Exhibit 4.5

ALEXION PHARMACEUTICALS, INC.
2017 INCENTIVE PLAN

1.DEFINED TERMS

Exhibit A, which is incorporated by reference, defines the terms used in the Plan and includes certain operational rules related to those terms.

2.PURPOSE

The Plan has been established to advance the interests of the Company by providing for the grant to Participants of Stock, Stock-based and other incentive Awards.

3.ADMINISTRATION

The Administrator has discretionary authority, subject only to the express provisions of the Plan, to interpret the Plan; determine eligibility for and grant Awards; determine, modify or waive the terms and conditions of any Award; determine the form of settlement of Awards (whether in cash, shares of Stock, or other property); prescribe forms, rules and procedures relating to the Plan and Awards; and otherwise do all things necessary or desirable to carry out the purposes of the Plan. Determinations of the Administrator made under the Plan are conclusive and will bind all persons.

4.LIMITS ON AWARDS UNDER THE PLAN

(a)Number of Shares. Subject to adjustment as provided in Section 7(b), the maximum number of shares of Stock that may be issued in satisfaction of Equity Awards under the Plan on and after the Effective Date shall be 18,500,000 shares, less one (1) share for every one (1) share that was subject to an option or stock appreciation right granted after March 14, 2017 under the Prior Plan and two (2) shares for every one (1) share that was subject to an award other than an option or stock appreciation right granted after March 14, 2017 under the Prior Plan, as further adjusted to include the number of shares that become available in accordance with Section 4(b) below. Subject to adjustment as provided in Section 7(b), after the Effective Date up to 6,000,000 shares of Stock may be issued under the Plan in satisfaction of ISOs, but nothing in this Section 4(a) will be construed as requiring that any, or any fixed number of, ISOs be awarded under the Plan.

(b)Share Counting Rules.

(1)Fungible Share Pool. Subject to adjustment as provided under Section 7(b), (A) any Stock Option or SARs shall be counted against the share limits specified in Section 4(a) as one (1) share for each share of Stock subject to such Stock Option or SAR, and (B) any full-value Equity Award (i.e., an Award that is not a Stock Option or SAR) shall be counted against the share limits specified in Section 4(a) as two (2) shares for each one share of Stock subject to such Award. To the extent a share that was subject to an Award or an award outstanding under the Prior Plan after March 14, 2017 is returned to the Plan pursuant to Section 4(b)(2), the share reserve will be credited on the same basis as described in the preceding sentence.

(2)Share Counting. Shares of Stock that are deliverable under an Award that is canceled, cash-settled, expired, forfeited, or otherwise terminated without the delivery of such shares (other than pursuant to clause (B) of Section 4(b)(3) below) will not be counted as delivered, and will remain available for delivery pursuant to Section 4(a) above. Shares of Stock delivered but subsequently forfeited such that those shares are returned to the Company will again be available for delivery pursuant to Section 4(a) above. In the event that withholding tax liabilities arising from a full-value Equity Award are satisfied by the tendering of shares of Stock (either actually or by attestation) or by the withholding of shares of Stock by the Company, the shares so tendered or withheld will again be available for delivery pursuant to Section 4(a) above. The provisions of this Section 4(b)(2) will apply on the same basis to awards outstanding under the Prior Plan after March 14, 2017 and, in accordance with the foregoing share counting rules, the applicable shares of Stock subject to such Prior Plan awards will again be available for delivery pursuant to Section 4(a).

(3)No Recycling of Stock Options or SARs. Notwithstanding anything to the contrary, the following shares of Stock will be counted as delivered, and will not again become available for delivery pursuant to Section 4(a) above: (A) shares of Stock tendered by a Participant or withheld by the Company as full or partial payment to the Company upon

exercise of Stock Options; (B) shares of Stock reserved for issuance upon stock-settlement of SARs, to the extent that the number of shares of Stock subject to such SARs exceeds the number of shares of Stock actually issued upon exercise of such SARs; (C) shares of Stock withheld by, or otherwise tendered or remitted to, the Company to satisfy a Participant’s tax withholding obligations upon the exercise of Stock Options or SARs; and (D) shares of Stock reacquired by the Company on the open market or otherwise using cash proceeds from the exercise of Stock Options.

(c)Substitute Awards. TheAdministrator may grant Substitute Awards under the Plan. To the extent consistent with the requirements of Section 422 and the regulations thereunder and other applicable legal requirements (including applicable stock exchange requirements), Stock issued under Substitute Awards will be in addition to and will not reduce the number of shares available for Awards under the Plan set forth in Section 4(a), but, notwithstanding anything in Section 4(a) to the contrary, if any Substitute Award is settled in cash or expires, becomes unexercisable, terminates or is forfeited to or repurchased by the Company without the issuance of Stock, the shares of Stock previously subject to such Award will not be available for future grants under the Plan. The Administrator will determine the extent to which the terms and conditions of the Plan apply to Substitute Awards, if at all, provided, however, that Substitute Awards will not be subject to the per-Participant Award limits described in Section 4(e) below.

(d)Type of Shares. Stock delivered by the Company under the Plan may be authorized but unissued Stock or previously issued Stock acquired by the Company. No fractional shares of Stock will be delivered under the Plan.

(e)Individual Limits.

(1)    The following additional limits apply to Awards of the specified type granted or, in the case of Cash Awards, payable to any person in any calendar year:

(A)    Stock Options: 600,000 shares of Stock.

(B)    SARs: 600,000 shares of Stock.

(C)    Awards other than Stock Options, SARs or Cash Awards: 600,000 shares of Stock.

(D)    Cash Awards: $5,000,000.

In applying the foregoing limits, (i) all Awards of the specified type granted to the same person in the same calendar year are aggregated and made subject to one limit; (ii) the limits applicable to Stock Options and SARs refer to the number of shares of Stock underlying those Awards; (iii) the share limit under clause (C) refers to the maximum number of shares of Stock that may be delivered, or the value of which could be paid in cash or other property, under an Award or Awards of the type specified in clause (C) assuming a maximum payout; (iv) Awards other than Cash Awards that are settled in cash count against the applicable share limit under clause (A), (B) or (C) and not against the dollar limit under clause (D); and (v) the dollar limit under clause (D) refers to the maximum dollar amount payable under a Cash Award assuming a maximum payout. To the extent applicable, the foregoing provisions will be construed in a manner consistent with Section 162(m), including, without limitation, where applicable, the rules under Section 162(m) pertaining to permissible deferrals of exempt awards.

(2)    Notwithstanding the foregoing limits, the maximum grant date fair value of Equity Awards (calculated in accordance with the Accounting Rules) granted to any Director in any calendar year, taken together with any cash fees paid during the calendar year to the Director, in each case, in respect of the Director’s service as a member of the Board during such year (including service as a member or chair of any committees of the Board), shall not exceed $750,000. The Board may make exceptions to this limit for a non-executive chair or lead director of the Board or, in extraordinary circumstances, for other individual Directors, as the Board may determine in its discretion, provided that the Director receiving such additional compensation may not participate in the decision to award such compensation.

5.ELIGIBILITY AND PARTICIPATION

The Administrator shall select Participants from among key Employees and Directors of, and consultants and advisors to, the Company and its subsidiaries. Eligibility for ISOs is limited to individuals described in the first sentence of this Section 5 who are employees of the Company or of a “parent corporation” or “subsidiary corporation” of the Company as those terms are defined in Section 424 of the Code. Eligibility for Stock Options, other than ISOs, and SARs is limited to individuals described in the first sentence of this Section 5 who are providing direct services on the date of grant of the Award to the

Company or to a subsidiary of the Company that would be described in the first sentence of Treas. Regs. §1.409A-1(b)(5)(iii)(E).

6.RULES APPLICABLE TO AWARDS

(a)All Awards.

(1)Award Provisions. The Administrator shall determine the terms of all Awards, subject to the limitations provided herein. By accepting (or, under such rules as the Administrator may prescribe, being deemed to have accepted) an Award, the Participant will be deemed to have agreed to the terms of the Award and the Plan. Notwithstanding any provision of this Plan to the contrary, Substitute Awards may contain terms and conditions that are inconsistent with the terms and conditions specified herein, as determined by the Administrator. No term of an Award shall provide for automatic, nondiscretionary “reload” grants of additional Awards upon the exercise of an Option or SAR or otherwise as a term of an Award.

(2)Term of Plan. The Plan shall be effective as of the Effective Date. No Awards may be made after 10 years from the Effective Date, but previously granted Awards may continue beyond that date in accordance with their terms. After the Effective Date, no awards may be granted under the Prior Plan. As of March 14, 2017, there were 9,751,090 shares of Stock underlying awards outstanding under the Prior Plan.

(3)Transferability. Neither ISOs nor, except as the Administrator otherwise expressly provides in accordance with the third sentence of this Section 6(a)(3), other Awards may be transferred other than by will or by the laws of descent and distribution. During a Participant’s lifetime, ISOs and, except as the Administrator otherwise expressly provides in accordance with the third sentence of this Section 6(a)(3), SARs and NSOs may be exercised only by the Participant. The Administrator may permit the gratuitous transfer (i.e., transfer not for value) of Awards other than ISOs, subject to applicable securities and other laws and such limitations as the Administrator may impose.

(4)Vesting, etc. The Administrator shall determine the time or times at which an Award vests or becomes exercisable and the terms on which a Stock Option or SAR remains exercisable. Without limiting the foregoing, the Administrator may at any time accelerate the vesting or exercisability of an Award, regardless of any adverse or potentially adverse tax or other consequences resulting from such acceleration. Unless the Administrator expressly provides otherwise, however, the following rules will apply if a Participant’s Employment ceases:

(A)    Except as provided in (B) and (C) below, immediately upon the cessation of the Participant’s Employment each Stock Option and SAR that is then held by the Participant or by the Participant’s permitted transferees, if any, will cease to be exercisable and will terminate and all other Awards that are then held by the Participant or by the Participant’s permitted transferees, if any, to the extent not already vested will be forfeited.

(B)    Subject to (C) and (D) below, all Stock Options and SARs held by the Participant or the Participant’s permitted transferees, if any, immediately prior to the cessation of the Participant’s Employment, to the extent then exercisable, will remain exercisable for the lesser of (i) a period of 90 days or (ii) the period ending on the latest date on which such Stock Option or SAR could have been exercised without regard to this Section 6(a)(4), and will thereupon immediately terminate.

(C)    Subject to (D) below, all Stock Options and SARs held by a Participant or the Participant’s permitted transferees, if any, immediately prior to the cessation of the Participant’s Employment due to death or Disability, to the extent then exercisable, will remain exercisable for the lesser of (i) the one year period ending with the first anniversary of the cessation of the Participant’s Employment (or, if the Participant’s Employment is terminated by reason of the Participant’s Disability and the Participant dies within one year of such cessation of Employment, then the first anniversary of the later death of such Participant) or (ii) the period ending on the latest date on which such Stock Option or SAR could have been exercised without regard to this Section 6(a)(4), and will thereupon immediately terminate.

(D)    All Stock Options and SARs (whether or not exercisable) held by a Participant or the Participant’s permitted transferees, if any, immediately prior to the cessation of the Participant’s Employment will immediately terminate upon such cessation of Employment if the termination is for Cause or occurs in circumstances that in the determination of the Administrator would have constituted grounds for the Participant’s Employment to be terminated for Cause.

(5)Recovery of Compensation. The Administrator may provide in any case that outstanding Awards (whether or not vested or exercisable) and the proceeds from the exercise or disposition of Awards or Stock acquired under Awards will be subject to forfeiture and disgorgement to the Company, with interest and other related earnings, if the Participant to whom the Award was granted violates (i) a non-competition, non-solicitation, confidentiality or other restrictive covenant by which he or she is bound, or (ii) any Company policy applicable to the Participant that provides for forfeiture or disgorgement with respect to incentive compensation that includes Awards under the Plan. In addition, the Administrator may require forfeiture and disgorgement to the Company of outstanding Awards and the proceeds from the exercise or disposition of Awards or Stock acquired under Awards, with interest and other related earnings, to the extent required by law or applicable stock exchange listing standards, including, without limitation, Section 10D of the Exchange Act and any related Company policy. Each Participant, by accepting or being deemed to have accepted an Award under the Plan, agrees to cooperate fully with the Administrator, and to cause any and all permitted transferees of the Participant to cooperate fully with the Administrator, to effectuate any forfeiture or disgorgement required hereunder. Neither the Administrator nor the Company nor any other person, other than the Participant and his or her permitted transferees, if any, will be responsible for any adverse tax or other consequences to a Participant or his or her permitted transferees, if any, that may arise in connection with this Section 6(a)(5).

(6)Taxes. The delivery, vesting and retention of Stock, cash or other property under an Award are conditioned upon full satisfaction by the Participant of all tax withholding requirements with respect to the Award. The Company and any subsidiary or affiliate is authorized to withhold from any Award granted, any payment relating to an Award under the Plan, including from a distribution of Stock, or any payroll or other payment to a Participant, amounts of withholding and other taxes due in connection with any transaction involving an Award, and to take such other action as the Administrator may deem advisable to enable the Company and Participants to satisfy obligations for the payment of withholding taxes and other tax obligations relating to any Award. This authority shall include authority to withhold or receive Stock or other property and to make cash payments in respect thereof in satisfaction of a Participant’s withholding obligations, either on a mandatory or elective basis in the discretion of the Administrator. The Administrator shall prescribe such rules for the withholding of taxes with respect to any Award as it deems necessary. The Administrator may hold back shares of Stock from an Equity Award or permit a Participant to tender previously owned shares of Stock in satisfaction of tax withholding requirements (but not in excess of the maximum withholding amount consistent with the award being subject to equity accounting treatment under the Accounting Rules).

(7)Dividend Equivalents, Etc. The Administrator may provide for the payment of amounts (on terms and subject to conditions established by the Administrator, including providing for the reinvestment of such amounts in the form of additional Equity Awards) in lieu of cash dividends or other cash distributions with respect to Stock subject to an Award whether or not the holder of such Award is otherwise entitled to share in the actual dividend or distribution in respect of such Award; provided, however, that notwithstanding anything to the contrary in the Plan (a) dividends or dividend equivalents relating to an Award that, at the dividend payment date, remains subject to a risk of forfeiture (whether service-based or performance-based) shall be subject to the same risk of forfeiture as applies to the underlying Award and (b) no dividends or dividend equivalents shall be payable with respect to Options or SARs prior to their exercise or settlement, as applicable. Any entitlement to dividend equivalents or similar entitlements will be established and administered either consistent with an exemption from, or in compliance with, the requirements of Section 409A. Dividends or dividend equivalent amounts payable in respect of Awards that are subject to restrictions may be subject to additional limits or restrictions as the Administrator may impose.

(8)Rights Limited. Nothing in the Plan may be construed as giving any person the right to be granted an Award or to continued employment or service with the Company or any of its subsidiaries, or any rights as a stockholder except as to shares of Stock actually issued under the Plan. The loss of existing or potential profit in Awards will not constitute an element of damages in the event of termination of Employment for any reason, even if the termination is in violation of an obligation of the Company or any of its subsidiaries to the Participant.

(9)Section 162(m). In the case of any Performance Award (other than a Stock Option or SAR) intended to qualify for the performance-based compensation exception under Section 162(m), the Administrator shall establish the Performance Criterion (or Criteria) applicable to the Award within the time period required under Section 162(m) and the grant, vesting or payment, as the case may be, of the Award will be conditioned upon the satisfaction of the Performance Criterion (or Criteria) as certified by the Administrator. The Administrator may grant an Annual Incentive Award to a Participant who is designated by the Administrator as likely to be a “covered employee” (within the meaning of Section 162(m)). Unless otherwise determined by the Administrator, such Annual Incentive Award will be intended to qualify as “performance-based compensation” for purposes of Section 162(m). The Administrator may establish a Performance Award pool, which shall be an unfunded pool, for purposes of measuring performance of the Company in connection with

Performance Awards, including Annual Incentive Awards. The amount of such Performance Award pool shall be based upon the achievement of a performance goal or goals based on one or more of the Performance Criteria during the given performance period, as specified by the Administrator. The Administrator may specify the amount of the Performance Award pool as a percentage of any of such business criteria, a percentage thereof in excess of a threshold amount, or as another amount which need not bear a strictly mathematical relationship to such business criteria.

(10)Coordination with Other Plans. Awards under the Plan may be granted in tandem with, or in satisfaction of or substitution for, other Awards under the Plan or awards made under other compensatory plans or programs of the Company or any of its subsidiaries. For example, but without limiting the generality of the foregoing, awards under other compensatory plans or programs of the Company or any of its subsidiaries may be settled in Stock (including, without limitation, Unrestricted Stock) under the Plan if the Administrator so determines, in which case the shares delivered will be treated as awarded under the Plan (and will reduce the number of shares thereafter available under the Plan in accordance with the rules set forth in Section 4). In any case where an award is made under another plan or program of the Company or any of its subsidiaries and is intended to qualify for the performance-based compensation exception under Section 162(m), and such award is settled by the delivery of Stock or another Award under the Plan, the applicable Section 162(m) limitations under both the other plan or program and under the Plan will be applied to the Plan as necessary (as determined by the Administrator) to preserve the availability of the Section 162(m) performance-based compensation exception with respect thereto.

(11)Section 409A.

(A)    Without limiting the generality of Section 11(b) hereof, each Award will contain such terms as the Administrator determines and will be construed and administered, such that the Award either qualifies for an exemption from the requirements of Section 409A or satisfies such requirements.

(B)    Notwithstanding Section 9 of this Plan or any other provision of this Plan or any Award agreement to the contrary, the Administrator may unilaterally amend, modify or terminate the Plan or any outstanding Award, including but not limited to changing the form of the Award, if the Administrator determines that such amendment, modification or termination is necessary or advisable to avoid the imposition of an additional tax, interest or penalty under Section 409A.

(C)    If a Participant is deemed on the date of the Participant’s termination of Employment to be a “specified employee” within the meaning of that term under Section 409A(a)(2)(B), then, with regard to any payment that is considered nonqualified deferred compensation under Section 409A, to the extent applicable, payable on account of a “separation from service”, such payment will be made or provided on the date that is the earlier of (i) the expiration of the six-month period measured from the date of such “separation from service” and (ii) the date of the Participant’s death (the “Delay Period”). Upon the expiration of the Delay Period, all payments delayed pursuant to this Section 6(a)(11)(C) (whether they would have otherwise been payable in a single lump sum or in installments in the absence of such delay) will be paid on the first business day following the expiration of the Delay Period in a lump sum and any remaining payments due under the Award will be paid in accordance with the normal payment dates specified for them in the applicable Award agreement.

(D)    For purposes of Section 409A, each payment made under this Plan will be treated as a separate payment.

(b)Stock Options and SARs.

(1)Time and Manner of Exercise. Unless the Administrator expressly provides otherwise, no Stock Option or SAR will be deemed to have been exercised until the Administrator receives notice of exercise in a form acceptable to the Administrator that is signed by the appropriate person and accompanied by any payment required under the Award. Any attempt to exercise a Stock Option or SAR by any person other than the Participant will not be given effect unless the Administrator has received such evidence as it may require that the person exercising the Award has the right to do so.

(2)Exercise Price. The exercise price (or the base value from which appreciation is to be measured) of each Award requiring exercise (other than a Substitute Award) must be no less than 100% (in the case of an ISO granted to a 10-percent stockholder within the meaning of subsection (b)(6) of Section 422, 110%) of the Fair Market Value of the Stock subject to the Award, determined as of the date of grant, or such higher amount as the Administrator may determine in connection with the grant.

(3)Payment of Exercise Price. Where the exercise of an Award is to be accompanied by payment, payment of the exercise price must be by cash or check acceptable to the Administrator or, if so permitted by the Administrator and if legally permissible, (i) through the delivery of previously acquired unrestricted shares of Stock, or the withholding of unrestricted shares of Stock otherwise deliverable upon exercise, in either case that have a Fair Market Value equal to the exercise price, (ii) through a broker-assisted exercise program acceptable to the Administrator, (iii) by other means acceptable to the Administrator, or (iv) by any combination of the foregoing permissible forms of payment. The delivery of previously acquired shares in payment of the exercise price under clause (i) above may be accomplished either by actual delivery or by constructive delivery through attestation of ownership, subject to such rules as the Administrator may prescribe.

(4)Maximum Term. The maximum term of Stock Options and SARs must not exceed 10 years from the date of grant (or five years from the date of grant in the case of an ISO granted to a 10-percent stockholder described in Section 6(b)(2) above).

(5)No Repricing. Except in connection with a corporate transaction involving the Company (which term includes, without limitation, any stock dividend, stock split, extraordinary cash dividend, recapitalization, reorganization, merger, consolidation, split-up, spin-off, combination or exchange of shares) or as otherwise contemplated by Section 7 below, the Company may not, without obtaining stockholder approval, (A) amend the terms of outstanding Stock Options or SARs to reduce the exercise price or base value of such Stock Options or SARs, (B) cancel outstanding Stock Options or SARs in exchange for Stock Options or SARs with an exercise price or base value that is less than the exercise price or base value of the original Stock Options or SARs, or (C) cancel outstanding Stock Options or SARs that have an exercise price or base value greater than the Fair Market Value of a share of Stock on the date of such cancellation in exchange for cash, another Award or other consideration.

7.EFFECT OF CERTAIN TRANSACTIONS

(a)Mergers,etc.Except as otherwise expressly provided in an Award agreement or by the Administrator, the following provisions will apply in the event of a Covered Transaction:

(1)Assumption or Substitution. If the Covered Transaction is one in which there is an acquiring or surviving entity, the Administrator may provide for (A) the assumption or continuation of some or all outstanding Awards or any portion thereof or (B) the grant of new awards in substitution therefor by the acquiror or survivor or an affiliate of the acquiror or survivor.

(2)Cash-Out of Awards. Subject to Section 7(a)(5) below, the Administrator may provide for payment (a “cash-out”), with respect to some or all Awards or any portion thereof, equal in the case of each affected Equity Award or portion thereof to the excess, if any, of (A) the Fair Market Value of one share of Stock times the number of shares of Stock subject to the Award or such portion, over (B) the aggregate exercise or purchase price, if any, under the Award or such portion (in the case of a SAR, the aggregate base value above which appreciation is measured), in each case on such payment terms (which need not be the same as the terms of payment to holders of Stock) and other terms, and subject to such conditions, as the Administrator determines; provided, however, for the avoidance of doubt, that if the exercise or purchase price (or base value) of an Equity Award is equal to or greater than the Fair Market Value of one share of Stock, the Award may be cancelled with no payment due hereunder or otherwise in respect of such Equity Award.

(3)Acceleration of Certain Awards. Subject to Section 7(a)(5) below, the Administrator may provide that any Award requiring exercise will become exercisable, in full or in part, and/or that the delivery of any shares of Stock remaining deliverable under any outstanding Award of Stock Units (including Restricted Stock Units and Performance Awards to the extent consisting of Stock Units) will be accelerated, in full or in part, in each case on a basis that gives the holder of the Award a reasonable opportunity, as determined by the Administrator, following exercise of the Award or the delivery of the shares, as the case may be, to participate as a stockholder in the Covered Transaction.

(4)Termination of Awards upon Consummation of Covered Transaction. Except as the Administrator may otherwise determine in any case, each Award will automatically terminate (and in the case of outstanding shares of Restricted Stock, will automatically be forfeited) immediately upon consummation of the Covered Transaction, other than (A) any Award that is assumed or substituted pursuant to Section 7(a)(1) above, and (B) any Cash Award that by its terms, or as a result of action taken by the Administrator, continues following the Covered Transaction.

(5)Additional Limitations. Any share of Stock and any cash or other property delivered pursuant to Section 7(a)(2) or Section 7(a)(3) above with respect to an Award may, in the discretion of the Administrator, contain such

restrictions, if any, as the Administrator deems appropriate to reflect any performance or other vesting conditions to which the Award was subject and that did not lapse (and were not satisfied) in connection with the Covered Transaction. For purposes of the immediately preceding sentence, a cash-out under Section 7(a)(2) above or an acceleration under Section 7(a)(3) above will not, in and of itself, be treated as the lapsing (or satisfaction) of a performance or other vesting condition. In the case of Restricted Stock that does not vest and is not forfeited in connection with the Covered Transaction, the Administrator may require that any amounts delivered, exchanged or otherwise paid in respect of such Stock in connection with the Covered Transaction be placed in escrow or otherwise made subject to such restrictions as the Administrator deems appropriate to carry out the intent of the Plan.

(b)Changes in and Distributions with Respect to Stock.

(1)Basic Adjustment Provisions. In the event of an extra ordinary cash dividend, stock dividend, spin-off, stock split or combination of shares (including a reverse stock split), recapitalization, reorganization, merger, consolidation or other change in the Company’s capital structure that constitutes an equity restructuring within the meaning of the Accounting Rules, the Administrator shall make appropriate adjustments to the maximum number of shares of Stock specified in Section 4(a) that may be issued under the Plan and to the maximum share limits described in Section 4(e), and shall make appropriate adjustments to the number and kind of shares of stock or securities underlying Equity Awards then outstanding or subsequently granted, any exercise or purchase prices (or base values) relating to Awards and any other provision of Awards affected by such change.

(2)Certain Other Adjustments. The Administrator may also make adjustments of the type described in Section 7(b)(1) above to take into account distributions to stockholders other than those provided for in Section 7(a) and 7(b)(1), or any other event, if the Administrator determines that adjustments are appropriate to avoid distortion in the operation of the Plan, having due regard for the qualification of ISOs under Section 422, the requirements of Section 409A, and the performance-based compensation rules of Section 162(m), to the extent applicable.

(3)Continuing Application of Plan Terms. References in the Plan to shares of Stock will be construed to include any stock or securities resulting from an adjustment pursuant to this Section 7.

8.LEGAL CONDITIONS ON DELIVERY OF STOCK

The Company will not be obligated to deliver any shares of Stock pursuant to the Plan or to remove any restriction from shares of Stock previously delivered under the Plan until: (i) the Company is satisfied that all legal matters in connection with the issuance and delivery of such shares have been addressed and resolved; (ii) if the outstanding Stock is at the time of delivery listed on any stock exchange or national market system, the shares to be delivered have been listed or authorized to be listed on such exchange or system upon official notice of issuance; and (iii) all conditions of the Award have been satisfied or waived. The Company may require, as a condition to the exercise of an Award or the delivery of shares of Stock under an Award, such representations or agreements as counsel for the Company may consider appropriate to avoid violation of the Securities Act of 1933, as amended, or any applicable state or non-U.S. securities law. Any Stock required to be issued to Participants under the Plan will be evidenced in such manner as the Administrator may deem appropriate, including book-entry registration or delivery of stock certificates. In the event that the Administrator determines that stock certificates will be issued to Participants under the Plan, the Administrator may require that certificates evidencing Stock issued under the Plan bear an appropriate legend reflecting any restriction on transfer applicable to such Stock, and the Company may hold the certificates pending lapse of the applicable restrictions.

9.AMENDMENT AND TERMINATION

The Administrator may at any time or times amend the Plan or any outstanding Award for any purpose which may at the time be permitted by law, and may at any time terminate the Plan as to any future grants of Awards; provided, however, that except as otherwise expressly provided in the Plan the Administrator may not, without the Participant’s consent, alter the terms of an Award so as to affect materially and adversely the Participant’s rights under the Award, unless the Administrator expressly reserved the right to do so at the time the Award was granted. Any amendments to the Plan will be conditioned upon stockholder approval only to the extent, if any, such approval is required by law (including the Code) or applicable stock exchange requirements, as determined by the Administrator.

10.OTHER COMPENSATION ARRANGEMENTS

The existence of the Plan or the grant of any Award will not affect the Company’s right to award a person bonuses or other compensation in addition to Awards under the Plan.

11.MISCELLANEOUS

(a)Waiver of Jury Trial. By accepting or being deemed to have accepted an Award under the Plan, each Participant waives any right to a trial by jury in any action, proceeding or counterclaim concerning any rights under the Plan and any Award, or under any amendment, waiver, consent, instrument, document or other agreement delivered or which in the future may be delivered in connection therewith, and agrees that any such action, proceedings or counterclaim will be tried before a court and not before a jury. By accepting or being deemed to have accepted an Award under the Plan, each Participant certifies that no officer, representative, or attorney of the Company has represented, expressly or otherwise, that the Company would not, in the event of any action, proceeding or counterclaim, seek to enforce the foregoing waivers. Notwithstanding anything to the contrary in the Plan, nothing herein is to be construed as limiting the ability of the Company and a Participant to agree to submit disputes arising under the terms of the Plan or any Award made hereunder to binding arbitration or as limiting the ability of the Company to require any eligible individual to agree to submit such disputes to binding arbitration as a condition of receiving an Award hereunder.

(b)Limitation of Liability. Notwithstanding anything to the contrary in the Plan, neither the Company, nor any of its subsidiaries, nor the Administrator, nor any person acting on behalf of the Company, any of its subsidiaries, or the Administrator, will be liable to any Participant, to any permitted transferee, to the estate or beneficiary of any Participant or any permitted transferee, or to any other holder of an Award by reason of any acceleration of income, or any additional tax (including any interest and penalties), asserted by reason of the failure of an Award to satisfy the requirements of Section 422 or Section 409A or by reason of Section 4999 of the Code, or otherwise asserted with respect to the Award.

12.ESTABLISHMENT OF SUB-PLANS

The Administrator may at any time and from time to time establish one or more sub-plans under the Plan (for local-law compliance purposes or other administrative reasons determined by the Administrator) by adopting supplements to the Plan containing, in each case, such limitations on the Administrator’s discretion under the Plan, and such additional terms and conditions, as the Administrator deems necessary or desirable. Each supplement so established will be deemed to be part of the Plan but will apply only to Participants within the group to which the supplement applies (as determined by the Administrator).

13.GOVERNING LAW

(a)Certain Requirements of Corporate Law. Equity Awards will be granted and administered consistent with the requirements of applicable Delaware law relating to the issuance of stock and the consideration to be received therefor, and with the applicable requirements of the stock exchanges or other trading systems on which the Stock is listed or entered for trading, in each case as determined by the Administrator.

(b)Other Matters. Except as otherwise provided by the express terms of an Award agreement, under a sub-plan described in Section 12 or as provided in Section 13(a) above, the domestic substantive laws of the State of Connecticut govern the provisions of the Plan and of Awards under the Plan and all claims or disputes arising out of or based upon the Plan or any Award under the Plan or relating to the subject matter hereof or thereof without giving effect to any choice or conflict of laws provision or rule that would cause the application of the domestic substantive laws of any other jurisdiction.

(c)Jurisdiction. By accepting an Award, each Participant will be deemed to (a) have submitted irrevocably and unconditionally to the jurisdiction of the federal and state courts located within the geographic boundaries of the United States District Court for the District of Connecticut for the purpose of any suit, action or other proceeding arising out of or based upon the Plan or any Award; (b) agree not to commence any suit, action or other proceeding arising out of or based upon the Plan or an Award, except in the federal and state courts located within the geographic boundaries of the United States District Court for the District of Connecticut; and (c) waive, and agree not to assert, by way of motion as a defense or otherwise, in any such suit, action or proceeding, any claim that he or she is not subject personally to the jurisdiction of the above-named courts that his or her property is exempt or immune from attachment or execution, that the suit, action or proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that the Plan or an Award or the subject matter thereof may not be enforced in or by such court.

EXHIBIT A

Definition of Terms

The following terms, when used in the Plan, have the meanings and are subject to the provisions set forth below:

“Accounting Rules”: Financial Accounting Standards Board Accounting Standards Codification Topic 718, or any successor provision.

“Administrator”: The Committee, except that the Committee may delegate (i) to one or more of its members (or one or more other members of the Board, including the full Board) such of its duties, powers and responsibilities as it may determine; (ii) to one or more officers of the Company the power to grant Awards to the extent permitted by Section 152 or 157(c) of the Delaware General Corporation Law; and (iii) to such Employees or other persons as it determines such ministerial tasks as it deems appropriate. In the event of any delegation described in the preceding sentence, the term “Administrator” will include the person or persons so delegated to the extent of such delegation.

“Annual Incentive Award”: means a Performance Award granted to a Participant representing a conditional right to receive cash, Stock or other Awards or payments, as determined by the Committee, based on performance in a performance period of up to and including one fiscal year.

“Award”: Any or a combination of the following:

(i) Stock Options.

(ii) SARs.

(iii) Restricted Stock.

(iv) Unrestricted Stock.

(v) Stock Units, including Restricted Stock Units.

(vi) Performance Awards.

(vii) Cash Awards.

(viii) Awards (other than Awards described in (i) through (vii) above) that are denominated or payable in, valued in whole or in part by reference to or convertible into or otherwise based on Stock.

“Board”: The Board of Directors of the Company.

“Cash Award”: An Award denominated in cash, which may include an Annual Incentive Award (to the extent denominated in cash).

“Cause”: In the case of any Participant who is party to an employment or severance-benefit agreement that contains a definition of “Cause,” the definition set forth in such agreement applies with respect to such Participant for purposes of the Plan for so long as such agreement is in effect. In every other case, “Cause” means, as determined by the Administrator, the Participant’s dishonesty, fraud, insubordination, willful misconduct, refusal to perform services, unsatisfactory performance of services, material breach of any written agreement between the Participant and the Company or any of its affiliates or other conduct by the Participant that could be expected to be harmful to the business, interests or reputation of the Company.

“Change in Control”: Unless otherwise provided in an Award agreement or in any other plan or agreement relating to the Award, after the Effective Date, the occurrence of any of the following:

(i) any Person (other than the Company, any trustee or other fiduciary holding securities under any employee benefit plan of the Company, or any company owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their ownership of the common stock of the Company) becomes the beneficial owner (except that a Person shall be deemed to be the beneficial owner of all shares that any such Person has the right to acquire pursuant to any agreement or arrangement or upon exercise of conversion rights, warrants or options or otherwise, without regard to the sixty day period

referred to in Rule 13d-3 under the Exchange Act), directly or indirectly, of securities of the Company or any Significant Subsidiary (as defined below), representing 50% or more of the combined voting power of the Company’s or such subsidiary’s then outstanding securities;

(ii) during any period of two consecutive years, individuals who at the beginning of such period constitute the Board, and any new director (other than a director designated by a person who has entered into an agreement with the Company to effect a transaction described in clause (i), (iii), or (iv) of this paragraph) whose election by the Board or nomination for election by the Company’s stockholders was approved by a vote of at least two-thirds of the directors then still in office who either were directors at the beginning of the two-year period or whose election or nomination for election was previously so approved but excluding for this purpose any such new director whose initial assumption of office occurs as a result of either an actual or threatened election contest (as such terms are used in Rule 14a-11 of Regulation 14A promulgated under the Exchange Act) or other actual or threatened solicitation of proxies or consents by or on behalf of an individual, corporation, partnership, group, associate or other entity or Person other than the Board, cease for any reason to constitute at least a majority of the Board;

(iii) the consummation of a merger or consolidation of the Company or any subsidiary owning directly or indirectly all or substantially all of the consolidated assets of the Company (a “Significant Subsidiary”) with any other corporation, other than a merger or consolidation which would result in the stockholders of the Company immediately prior to such merger or consolidation holding, directly or indirectly, more than 50% of the combined voting power of the surviving or resulting entity outstanding immediately after such merger or consolidation in substantially the same proportions as their ownership of the Stock immediately prior to such merger or consolidation ; or

(iv) the consummation of a sale or disposition of all or substantially all of the consolidated assets of the Company (other than such a sale or disposition immediately after which such assets will be owned directly or indirectly by the stockholders of the Company in substantially the same proportions as their ownership of the common stock of the Company immediately prior to such sale or disposition).

Solely with respect to any Award that constitutes “nonqualified deferred compensation” subject to Section 409A and that is payable on account of a Change in Control (including any installments or stream of payments that are accelerated on account of a Change in Control), a Change in Control shall occur only if such event also constitutes a “change in the ownership”, “change in effective control”, and/or a “change in the ownership of a substantial portion of assets” of the Company as those terms are defined under Treasury Regulation §1.409A-3(i)(5), but only to the extent necessary to establish a time or form of payment that complies with Section 409A without altering the definition of Change in Control for purposes of determining whether a Participant’s rights to such Award become vested or otherwise unconditional upon the Change in Control.

“Code”: The U.S. Internal Revenue Code of 1986, as from time to time amended and in effect, or any successor statute as from time to time in effect.

“Committee”: The Leadership and Compensation Committee of the Board.

“Company”: Alexion Pharmaceuticals, Inc., a Delaware corporation.

“Covered Transaction”: Any of the consummation of (i) a consolidation, merger or similar transaction or series of related transactions, including a sale or other disposition of stock, in which the Company is not the surviving corporation or which results in the acquisition of all or substantially all of the Company’s then outstanding common stock by a single person or entity or by a group of persons and/or entities acting in concert, (ii) a sale or transfer of all or substantially all the Company’s assets, (iii) a dissolution or liquidation of the Company or (iv) a Change in Control. Where a Covered Transaction involves a tender offer that is reasonably expected to be followed by a merger described in clause (i) (as determined by the Administrator), the Covered Transaction will be deemed to have occurred upon consummation of the tender offer.

Solely with respect to any Award that constitutes “nonqualified deferred compensation” subject to Section 409A and that is payable on account of a Covered Transaction (including any installments or stream of payments that are accelerated on account of a Covered Transaction), a Covered Transaction shall occur only if such event also constitutes a “change in the ownership”, “change in effective control”, and/or a “change in the ownership of a substantial portion of assets” of the Company as those terms are defined under Treasury Regulation §1.409A-3(i)(5), but only to the extent necessary to establish a time or form of payment that complies with Section 409A without altering the definition of Covered Transaction for purposes of determining whether a Participant’s rights to such Award become vested or otherwise unconditional upon the Covered Transaction.

“Director”: A member of the Board who is not an Employee.

“Disability”: In the case of any Participant who is party to an employment or severance-benefit agreement that contains a definition of “Disability,” the definition set forth in such agreement applies with respect to such Participant for purposes of the Plan for so long as such agreement is in effect. In every other case, “Disability” shall mean the inability of a Participant to perform the customary duties of his or her Employment by reason of a physical or mental incapacity which is expected to result in death or to be of indefinite duration.

“Effective Date”: The date the Plan is approved by the Company’s stockholders.

“Employee”: Any person who is employed by the Company or any of its subsidiaries.

“Employment”: A Participant’s employment or other service relationship with the Company or any of its subsidiaries. Employment will be deemed to continue, unless the Administrator expressly provides otherwise, so long as the Participant is employed by, or otherwise is providing services in a capacity described in Section 5 to, the Company or any of its subsidiaries. If a Participant’s employment or other service relationship is with any subsidiary of the Company and that entity ceases to be a subsidiary of the Company, the Participant’s Employment will be deemed to have terminated when the entity ceases to be a subsidiary of the Company unless the Participant transfers Employment to the Company or any of its remaining subsidiaries. Notwithstanding the foregoing, in construing the provisions of any Award relating to the payment of “nonqualified deferred compensation” (subject to Section 409A) upon a termination or cessation of Employment, references to termination or cessation of employment, separation from service, retirement or similar or correlative terms will be construed to require a “separation from service” (as that term is defined in Section 1.409A-1(h) of the Treasury Regulations) from the Company and from all other corporations and trades or businesses, if any, that would be treated as a single “service recipient” with the Company under Section 1.409A-1(h)(3) of the Treasury Regulations. The Company may, but need not, elect in writing, subject to the applicable limitations under Section 409A, any of the special elective rules prescribed in Section 1.409A-1(h) of the Treasury Regulations for purposes of determining whether a “separation from service” has occurred. Any such written election will be deemed a part of the Plan.

“Equity Award”: An Award other than a Cash Award.

“Exchange Act”: The Securities Exchange Act of 1934, as amended.

“Prior Plan”: The Company’s Amended and Restated 2004 Incentive Plan as in effect immediately prior to the Effective Date.

“Fair Market Value”: As of a particular date, the fair market value of Stock, Awards or other property as determined by the Administrator or under procedures established by the Administrator, in accordance, where applicable, with the requirements of Section 422 and Section 409A. Unless otherwise determined by the Administrator, the Fair Market Value of Stock as of a particular date shall be the closing sale price per share of Stock reported on the principal stock exchange or market on which Stock is traded on the date as of which such value is being determined or, if there is no sale on that day, then on the last previous day on which a sale was reported.

“ISO”: A Stock Option intended to be an “incentive stock option” within the meaning of Section 422. Each Stock Option granted pursuant to the Plan will be treated as providing by its terms that it is to be an NSO unless, as of the date of grant, it is expressly designated as an ISO.

“NSO”: A Stock Option that is not intended to be an “incentive stock option” within the meaning of Section 422.

“Participant”: A person who is granted an Award under the Plan.

“Performance Award”: An Award subject to Performance Criteria. The Administrator may grant Performance Awards that are intended to qualify for the performance-based compensation exception under Section 162(m) and Performance Awards that are not intended to so qualify.

“Performance Criteria”: Specified criteria, other than the mere continuation of Employment or the mere passage of time, the satisfaction of which is a condition for the grant, exercisability, vesting or full enjoyment of an Award. A Performance Criterion and any targets with respect thereto need not be based upon an increase, a positive or improved result or avoidance of loss. For purposes of Awards that are intended to qualify for the performance-based compensation exception under Section 162(m), a Performance Criterion will mean an objectively determinable measure or objectively determinable measures of

performance relating to any, or any combination of, the following (measured either absolutely or comparatively (including, without limitation, by reference to an index or indices or the performance of one or more companies) and determined either on a consolidated Company basis or, as the context permits, on a divisional, subsidiary, line of business, project or geographical basis or in combinations thereof and subject to such adjustments, if any, as the Committee specifies, consistent with the requirements of Section 162(m)): sales; revenues; assets; expenses; earnings from operations, before or after taxes, or before or after deduction for all or any portion of interest, depreciation, amortization, incentives, service fees or extraordinary or special items, whether or not on a continuing operations or an aggregate or per share basis; net income or net income per common share (basic or diluted); return on assets, return on investment, return on capital, or return on equity; cash flow, free cash flow, cash flow return on investment, or net cash provided by operations; economic value created or added; operating margin or profit margin; stock price, dividends or total stockholder return; development of new technologies or products; raising or refinancing of capital; successful hiring of key individuals; resolution of significant litigation; one or more operating ratios; borrowing levels; leverage ratios or credit rating; market share; capital expenditures; recapitalizations, restructurings, financings (issuance of debt or equity) or refinancings; and strategic business criteria, consisting of one or more objectives based on the following goals: meeting specified market penetration or value added, product development or introduction (including, without limitation, any clinical trial accomplishments, regulatory or other filings or approvals, or other product development milestones), geographic business expansion, cost targets, cost reductions or savings, customer satisfaction, operating efficiency, acquisition or retention, employee satisfaction, information technology, corporate development (including, without limitation, licenses, innovation, research or establishment of third party collaborations), manufacturing or process development, legal compliance or risk reduction, patent application or issuance goals, or goals relating to acquisitions or divestitures (in whole or in part), joint ventures or strategic alliances. Any Performance Criteria that are financial metrics may be determined in accordance with United States Generally Accepted Accounting Principles (“GAAP”) or may be adjusted when established (or to the extent permitted under Section 162(m) at any time thereafter) to include or exclude any items otherwise includable or excludable under GAAP. Provided that the Administrator has specified at least one Performance Criteria intended to qualify an Award as performance-based under Section 162(m), the Administrator may specify other performance goals or criteria (whether or not listed herein) as a basis for its exercise of negative discretion with respect to the Award. To the extent consistent with the requirements for satisfying the performance-based compensation exception under Section 162(m), or as otherwise determined by the Administrator, the Administrator may provide in the case of any Award intended to qualify for such exception that one or more of the Performance Criteria applicable to such Award will be adjusted in an objectively determinable manner to reflect events occurring during the performance period such as: (i) asset write-downs or impairments, (ii) litigation or claim judgments or settlements, (iii) the effect of changes in tax law, accounting principles or other such laws or provisions affecting reporting results, (iv) accruals for reorganizations and restructuring programs, (v) impact of foreign exchange gains and losses, and (vi) any item of an unusual nature or of a type that indicates infrequency of occurrence, or both, including those described in the Financial Accounting Standards Board’s authoritative guidance, footnotes to the Company’s financial statements and/or in management’s discussion and analysis of financial condition and results of operations appearing in the Company’s reports on Form 10-K, 10-Q or 8-K for the applicable year.

“Plan”: The Alexion Pharmaceuticals, Inc. 2017 Incentive Plan, as from time to time amended and in effect.

“Restricted Stock”: Stock subject to restrictions requiring that it be redelivered or offered for sale to the Company if specified service or performance-based conditions are not satisfied.

“Restricted Stock Unit”: A Stock Unit that is, or as to which the delivery of Stock or cash in lieu of Stock is, subject to the satisfaction of specified performance or other vesting conditions.

“SAR”: A right entitling the holder upon exercise to receive an amount (payable in cash or in shares of Stock of equivalent value) equal to the excess of the Fair Market Value of the shares of Stock subject to the right over the base value from which appreciation under the SAR is to be measured.

“Section 409A”: Section 409A of the Code.

“Section 422”: Section 422 of the Code.

“Section 162(m)”: Section 162(m) of the Code.

“Stock”: Common stock of the Company, par value $0.0001 per share.

“Stock Option”: An option entitling the holder to acquire shares of Stock upon payment of the exercise price.

“Stock Unit”: An unfunded and unsecured promise, denominated in shares of Stock, to deliver Stock or cash measured by the value of Stock in the future.

“Substitute Awards”: EquityAwards issued under the Plan in substitution for equity awards of an acquired company that are converted, replaced or adjusted in connection with the acquisition.

“Unrestricted Stock”: Stock not subject to any restrictions under the terms of the Award.