Exhibit 10.4

SHARE SUBSCRIPTION AGREEMENT
 
By and Between
 
Celgene Switzerland LLC
 
and
 
Prothena Corporation plc
 
Dated as of March 20, 2018

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PROTHENA CORPORATION PLC
SHARE SUBSCRIPTION AGREEMENT
THIS SHARE SUBSCRIPTION AGREEMENT (the “Agreement”) is made and entered into as
of March 20, 2018 (the “Signing Date”), by and between Prothena Corporation plc,
an Irish public limited company (the “Company”), and Celgene Switzerland LLC, a
Delaware limited liability company (the “Subscriber”).
WHEREAS, the Company and the Subscriber are entering into that certain Master
Collaboration Agreement, by and between the Company and Subscriber, of even date
herewith (the “Collaboration Agreement”);
WHEREAS, the obligations in the Collaboration Agreement are conditioned upon the
execution and delivery of this Agreement, pursuant to which the Subscriber will
subscribe for and the Company will issue to the Subscriber a number of its
Ordinary Shares (as defined herein), as provided for herein; and
WHEREAS, the Subscriber desires to subscribe for, and the Company desires to
issue, the Shares (as defined herein) on the terms and conditions set forth
herein;
NOW, THEREFORE, in consideration of the foregoing recitals and the mutual
promises, representations, warranties and covenants hereinafter set forth and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto agree as follows:
1.Definitions.  When used in this Agreement, the following terms shall have the
respective meanings specified below:

“Action” shall mean any action, cause or action, suit, prosecution,
investigation, litigation, arbitration, hearing, order, claim, complaint or
other proceeding (whether civil, criminal, administrative, investigative or
informal) by or before any Governmental Authority or arbitrator.
“Affiliate” shall mean, with respect to any Person, another Person which
controls, is controlled by or is under common control with such Person. A Person
shall be deemed to control another Person if such Person possesses, directly or
indirectly, the power to direct or cause the direction of the management and
policies of such Person, whether through the ownership of voting securities, by
contract or otherwise. For the purposes of this Agreement, in no event shall the
Subscriber or any of its Affiliates be deemed Affiliates of the Company or any
of its Affiliates, nor shall the Company or any of its Affiliates be deemed
Affiliates of the Subscriber or any of its Affiliates.
“beneficially owns” (including the correlative terms “beneficial ownership,”
“beneficially owned,” “beneficial owner” or “beneficially owning”) shall mean
beneficial ownership within the meaning of Rule 13d-3 and Rule 13d-5 under the
Exchange Act.

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“Business Day” shall mean any day except Saturday, Sunday and any day on which
banking institutions in New York, New York, generally are closed as a result of
federal, state or local holiday.
“Change of Control” shall mean, with respect to a Person, any of the following
events: (i) any Person is or becomes the beneficial owner (as such term is
defined in Rule 13d-3 under the Exchange Act, except that a Person shall be
deemed to have beneficial ownership of all shares that any such Person has the
right to acquire, whether such right which may be exercised immediately or only
after the passage of time), directly or indirectly, of a majority of the total
voting power represented by all shares of such Person’s outstanding capital
stock; (ii) such Person consolidates with or merges into another corporation or
entity, or any corporation or entity consolidates with or merges into such
Person, other than (A) a merger or consolidation which would result in the
voting securities of such Person outstanding immediately prior to such merger or
consolidation continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity or any parent
thereof) a majority of the combined voting power of the voting securities of
such Person or such surviving entity or any parent thereof outstanding
immediately after such merger or consolidation, or (B) a merger or consolidation
effected to implement a recapitalization of such Person (or similar transaction)
in which no Person becomes the beneficial owner, directly or indirectly, of a
majority of the total voting power of all shares of capital stock of such Person
or (iii) such Person conveys, transfers or leases all or substantially all of
its assets, to any Person other than a wholly owned Affiliate of such Person.
“Code” shall mean the United States Internal Revenue Code of 1986, as amended.
“Consent” shall mean any, internal or external, approval, authorization,
consent, license, franchise, Order, registration, notification, permit,
certification, clearance, waiver or other confirmation of or by a Governmental
Authority, other Person or company body.
“Contract” shall mean, with respect to any Person, any written agreement,
contract, commitment, indenture, note, bond, loan, license, sublicense, lease,
sublease, undertaking, statement of work or other arrangement to which such
Person is a party or by which any of its properties or assets are subject.
“control” (including the correlative terms “controlled by,” “controlling” and
“under common control with”), as applied to any Person, shall mean the
possession, directly or indirectly, of the power to direct or cause the
direction of the management and policies of that Person, whether through the
ownership or voting of securities, by contract or otherwise.
“Controlled Affiliate” shall mean, with respect to a Person, an Affiliate of
such Person controlled by such Person.
“Disposition” or “Dispose of” shall mean any (i) offer, pledge, sale, contract
to sell, sale of any option or contract to purchase, purchase of any option or
contract to sell, grant of any option, right or warrant for the sale of, or
other disposition of or transfer of any Ordinary Shares or Ordinary Share
Equivalents, including, without limitation, any “short sale” or similar
arrangement, or (ii) swap, hedge, derivative instrument, or any other agreement
or any transaction that transfers, in whole or in part, directly or indirectly,
the economic consequence of ownership of Ordinary Shares

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or Ordinary Share Equivalents, whether any such swap or transaction is to be
settled by delivery of securities, in cash or otherwise.
“Employee Benefit Plan” shall mean any “employee benefit plan” (as such term is
defined in Section 3(3) of ERISA, whether or not subject to ERISA), any
severance, employment, incentive or bonus, retention, change in control,
deferred compensation, termination pay, profit sharing, retirement, welfare,
post-employment welfare, fringe benefit, vacation or paid time off, equity or
equity-based or any other plan, policy, program, agreement, contract or
arrangement that is sponsored, maintained, contributed to, or required to be
contributed to by the Company or any of its Subsidiaries or under or with
respect to which the Company or any of its Subsidiaries has any current or
contingent liability or obligation.
“Environmental Law” shall mean all national, supra-national, federal, state,
local and foreign Laws concerning public health and safety, worker health and
safety, pollution or protection of the environment; including without limitation
all those relating to the generation, handling, transportation, treatment,
storage, disposal, release, exposure to or cleanup of hazardous materials,
substances or wastes, including petroleum, asbestos, polychlorinated biphenyls,
asbestos, noise or radiation.
“ERISA” shall mean the United States Employee Retirement Income Security Act of
1974, as amended, and the rulings and regulations thereunder.
“Exchange Act” shall mean the U.S. Securities Exchange Act of 1934, as amended,
and the rules and regulations promulgated thereunder.
“FDA” shall mean the U.S. Food and Drug Administration.
“FDCA” shall mean the U.S. Federal Food, Drug and Cosmetic Act.
“GAAP” shall mean generally accepted accounting principles in the United States.
“Governmental Authority” shall mean any court, agency, authority, department,
regulatory body or other instrumentality of any government or country or of any
national, federal, state, provincial, regional, county, city or other political
subdivision of any such government or country or any supranational organization
of which any such country is a member.
“Health Care Laws” means statutes, laws, ordinances, rules and regulations
applicable to the Company for the ownership, testing, development, manufacture,
packaging, processing, use, labeling, promotion, storage, import, export or
disposal of any product manufactured or distributed by the Company, including
without limitation, the Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 301,
et seq., similar laws of other Governmental Authorities and the regulations
promulgated pursuant to such laws.
“Intellectual Property” shall mean all intellectual property and other similar
proprietary rights in any jurisdiction, including such rights in and to: (a) any
patent (including all reissues, divisions, continuations, continuations-in-part
and extensions thereof), patent application, patent disclosure or other patent
right, (b) any trademark, service mark, trade name, business name, brand

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name, slogan, logo, trade dress and all other indicia of origin together with
all goodwill associated therewith, and all registrations, applications for
registration, and renewals for any of the foregoing, (c) any copyright, work of
authorship (whether or not copyrightable), design, design registration, database
rights, and all registrations, applications for registration, and renewals for
any of the foregoing (and including in all website content and software), (d)
any Internet domain names, and (e) any trade secret, confidential information,
know-how and inventions, including processes and formulations.
“Knowledge” shall mean, when used with respect to the Company, the actual or
constructive knowledge of any officer of the Company, after due inquiry.
“Law” or “Laws” shall mean all laws, statutes, rules, regulations, orders,
judgments, injunctions and ordinances of any Governmental Authority.
“Leased Real Property” shall mean all leasehold or subleasehold estates and all
other rights to use or occupy any land, buildings, structures, improvements,
fixtures or other interest in real property held by the Company or any of its
Subsidiaries pursuant to any Lease.
“Leases” shall mean all leases, subleases, licenses, concessions and other
Contracts pursuant to which the Company or any of its Subsidiaries holds any
Leased Real Property as tenant, sublease, licensee or concessionaire (including
the rights to all security deposits and other amounts and instruments deposited
by or on behalf of the Company or and of its Subsidiaries thereunder) and all
material amendments, extensions, renewals, guaranties and other agreements with
respect thereto.
“Liens” shall mean a lien, charge, security interest, encumbrance, right of
first refusal, preemptive right or other restriction.
“Lock-Up Period” shall mean the period from and after the Closing Date until the
earlier of (i) the six-month anniversary of the Closing Date or (ii) the
expiration of the Term (as defined in the Collaboration Agreement) or earlier
termination of the Collaboration Agreement.
“Material Adverse Effect” shall mean any change, event or occurrence (each, an
“Effect”) that, individually or when taken together with all other effects that
have occurred prior to the date of determination of the occurrence of the
Material Adverse Effect, is or is likely to be materially adverse to the
business, clinical or pre-clinical programs, intellectual property, condition
(financial or other), assets, liabilities or results of operations of the
Company and its Subsidiaries, taken as a whole; provided, however, that in no
event shall any of the following occurring after the date hereof, alone or in
combination, be deemed to constitute, or be taken into account in determining
whether a Material Adverse Effect has occurred: (i) changes in the Company’s
industry generally or in conditions in the global economy or capital or
financial markets generally, including changes in interest or exchange rates,
(ii) any Effect caused by the announcement or pendency of the transactions
contemplated by the Transaction Agreements, or the identity of the Subscriber or
any of its Affiliates as the Subscriber in connection with the transactions
contemplated by this Agreement or as a participant in the Collaboration
Agreement, (iii) the performance of this Agreement, the Collaboration Agreement
and the transactions contemplated hereby and thereby, including

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compliance with the covenants set forth herein and therein, or any action taken
or omitted to be taken by the Company at the request or with the prior consent
of the Subscriber, (iv) changes in general legal, regulatory, political,
economic or business conditions or changes to GAAP or interpretations thereof
occurring after the date hereof that, in each case, generally affect the
biotechnology or biopharmaceutical industries, (v) acts of war, sabotage or
terrorism occurring after the date hereof, or any escalation or worsening of any
such acts of war, sabotage or terrorism or (vi) earthquakes, hurricanes, floods
or other natural disasters occurring after the date hereof, provided, however,
that with respect to clauses (i), (iv), (v) and (vi), such effects, alone or in
combination, may be deemed to constitute, or be taken into account in
determining whether a Material Adverse Effect has occurred, but only to the
extent such effects disproportionately affect the Company and its Subsidiaries
compared to other participants in the biotechnology or biopharmaceutical
industries.
“Material Contract” shall mean any Contract entered into by the Company or any
of its Subsidiaries that is required under the Exchange Act to be filed as an
exhibit to a Company SEC Document pursuant to Item 601(b)(10) of Regulation S-K.
“Nasdaq” shall mean the Nasdaq Stock Market LLC.
“Ordinary Share Equivalents” means any securities of the Company which would
entitle the holder thereof to acquire at any time Ordinary Shares, including,
without limitation, any debt, preferred shares, rights, options, warrants or
other instrument that is at any time convertible into or exercisable or
exchangeable for, or otherwise entitles the holder thereof to receive, Ordinary
Shares.
“Ordinary Shares” shall mean ordinary shares, par value $0.01 per share, of the
Company.
“Order” shall mean any assessment, award, decision, injunction, judgment, order,
ruling, verdict or writ entered, issued, made, or rendered by any court,
administrative agency, or other Governmental Authority or by any arbitrator.
“Permitted Liens” shall mean (a) mechanics’, materialman’s, workmens’,
repairmens’, warehousemen’s, supplier’s, vendor’s, carrier’s and other similar
Liens arising or incurred in the ordinary course of business by operation of Law
securing amounts that are not yet due and payable, (b) Liens for Taxes,
assessments and other charges of Governmental Authorities not yet due and
payable and Taxes being contested in good faith, (c) Liens arising under
original purchase price conditional sales Contracts and equipment leases with
third parties, (d) pledges or deposits to secure obligations under workers or
unemployment compensation Laws or to secure other statutory obligations, (e)
easements, covenants, conditions and restrictions of record affecting title to
the Leased Real Property which do not or would not materially impair the use or
occupancy of any Leased Real Property in the operation of the business conducted
thereon as of the date of this Agreement, and (f) any zoning, or other
governmentally established restrictions of encumbrances.
“Permitted Transferee” shall mean an Affiliate of the Subscriber that is wholly
owned, directly or indirectly, by the Subscriber; it being understood that for
purposes of this definition “wholly owned” shall mean an Affiliate in which the
Subscriber owns, directly or indirectly, at least ninety-nine percent (99%) of
the outstanding capital stock or ownership interests of such Affiliate;
provided, however, that no such Person shall be deemed a Permitted Transferee
for any purpose

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under this Agreement unless: (a) the Subscriber shall have, within five days
prior to such transfer, furnished to the Company written notice of the name and
address of such Permitted Transferee, details of its status as a Permitted
Transferee and details of the Ordinary Shares or Ordinary Share Equivalents to
be transferred, (b) the Permitted Transferee, prior to or simultaneously with
such Transfer, shall have agreed in writing to be subject to and bound by all
restrictions and obligations set forth in this Agreement as though it were the
Subscriber hereunder, and (c) the Subscriber acknowledges that it continues to
be bound by all restrictions and obligations set forth in this Agreement.
“Person” shall mean any individual, partnership, limited liability company,
firm, corporation, trust, unincorporated organization, government or any
department or agency thereof or other entity, as well as any syndicate or group
that would be deemed to be a Person under Section 13(d)(3) of the Exchange Act.
“SEC” shall mean the U.S. Securities and Exchange Commission.
“Securities Act” shall mean the U.S. Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.
“Standstill Period” shall mean the period from and after the Closing Date until
the earliest of (i) the one-year anniversary of the Closing Date, (ii) the date
the Company publicly announces its intent to initiate or consummate any merger,
consolidation, acquisition, scheme, business combination or other extraordinary
transaction in which the Company or any of its Subsidiaries is a constituent
entity or party, (iii) the submission or announcement of the intent to make any
bona fide offer or attempt by any third party to acquire all or a substantial
portion of the securities or assets of the Company through any means, process or
structure and (iv) the expiration of the Term (as defined in the Collaboration
Agreement) or earlier termination of the Collaboration Agreement.
“Tax” or “Taxes” shall mean any federal, state, local, or non-U.S. income, gross
receipts, license, payroll, employment, excise, severance, stamp, occupation,
premium, windfall profits, environmental, customs duties, capital stock,
franchise, profits, withholding, social security (or similar), unemployment,
disability, real property, personal property, sales, use, transfer,
registration, value added, alternative or add-on minimum, estimated, or other
tax of any kind whatsoever, including any interest, penalty, or addition
thereto, whether disputed or not.
“Tax Authority” shall mean any Governmental Authority having jurisdiction with
respect to any Tax.
“Tax Return” shall mean any return, declaration, report, claim for refund, or
information return or statement relating to Taxes, including any schedule or
attachment thereto, and including any amendment thereof, required to be filed
with a Tax Authority.
“Third Party” shall mean any Person (other than a Governmental Authority) other
than the Subscriber, the Company or any Affiliate of the Subscriber or the
Company.
“Transaction Agreements” shall mean this Agreement and the Collaboration
Agreement.

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“Transfer” by any Person means directly or indirectly, to sell, transfer,
assign, pledge, encumber, hypothecate or similarly Dispose of, either
voluntarily or involuntarily, or to enter into any contract, option or other
arrangement or understanding with respect to the sale, transfer, assignment,
pledge, encumbrance, hypothecation or similar Disposition of, any securities
beneficially owned by such Person or of any interest (including any voting
interest) in any securities beneficially owned by such Person. For the avoidance
of doubt, a transfer of control of the direct or indirect beneficial ownership
of securities is a Transfer of such securities for purposes of this Agreement.
“Transfer Agent” shall mean Computershare Trust Company, N.A., or any successor
transfer agent of the Company, as applicable.
“WARN Act” shall mean the Worker Adjustment and Retraining Notification Act of
1988, as amended and any similar or related Law.
2.    Closing, Delivery and Payment.
2.1    Closing.  Subject to the terms and conditions hereof, and in reliance on
the representations, warranties, covenants and other agreements hereinafter set
forth, at the closing of the transactions contemplated hereby (the “Closing”),
the Company hereby agrees to issue to the Subscriber, and the Subscriber agrees
to subscribe for, 1,170,960 Ordinary Shares (the “Shares”) at a price of
$42.70 per Share, free and clear of all Liens and any withholding for Taxes, for
an aggregate price of $49,999,992.00 (the “Share Price”).  The Closing shall
take place remotely via the exchange of documents and signatures, as soon as
practicable, but in no event later than at 2:00 p.m. Eastern Time on the first
Business Day immediately following the date on which the last of the conditions
set forth in Section 6 has been satisfied or waived (other than those conditions
that by their nature can only be satisfied at the Closing), or at such other
date and time as the Company and Subscriber shall mutually agree (which date and
time are designated as the “Closing Date”).
2.2    Delivery and Payment.  At the Closing, subject to the terms and
conditions hereof, the Company will instruct the Transfer Agent to deliver to
the Subscriber, via book entry to the applicable balance account registered in
the name of the Subscriber, the Shares, against payment of the Share Price in
U.S. dollars by wire transfer of immediately available funds to the order of the
Company.
2.3    Deliveries at Closing.
(a)    Deliveries by the Company. At the Closing, the Company shall deliver or
cause to be delivered to the Subscriber the following items:
(i)a true copy of the constitution (the “Constitution”) of the Company;

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(ii)    a copy of the irrevocable instructions to the Transfer Agent instructing
the Transfer Agent to deliver the Shares to Subscriber on an expedited basis;
(iii)    a legal opinion of A&L Goodbody, the Company’s Irish counsel, addressed
to the Subscriber, and dated the Closing Date, in substantially the form
provided to the Subscriber on the date hereof;
(iv)    a legal opinion of Latham & Watkins LLP, U.S. counsel for the Company,
addressed to the Subscriber, and dated the Closing Date, in substantially the
form provided to the Subscriber on the date hereof;
(v)    a certificate, dated as of the Closing Date, signed by the Company’s
principal financial officer confirming that the conditions to the Closing set
forth in Section 6.1 have been satisfied; and
(vi)    all such other documents, certificates and instruments as the Subscriber
may reasonably request in order to give effect to the transactions contemplated
hereby.
(b)    Deliveries by the Subscriber.  At the Closing, the Subscriber shall
deliver or cause to be delivered to the Company the Share Price, by wire
transfer of immediately available funds to one or more accounts designated by
the Company, such designation to be made via written notice to the Subscriber no
later than three (3) Business Days prior to the Closing Date.
3.    Representations and Warranties of the Company.  The Company hereby
represents and warrants to the Subscriber that the following representations are
true and complete as of the Closing Date, except as otherwise indicated or as
set forth in the Company SEC Documents, and only to the extent such Company SEC
Documents are specifically referenced in such representation or warranty.

3.1    Organization, Good Standing and Qualification.
(a)    The Company is duly incorporated and validly existing as a public limited
company under the laws of Ireland.  The Company has all requisite corporate
power and authority to own and operate its properties, to execute and deliver
this Agreement, to carry out the provisions of this Agreement (including, but
not limited to, the issuance and delivery of the Shares) and to carry on its
business as presently conducted and as presently proposed to be conducted. Each
of the Company’s Subsidiaries (as defined herein) is an entity duly incorporated
or otherwise organized, validly existing and in good standing (to the extent
such concept exists in the relevant jurisdiction) under the Laws of the
jurisdiction of its incorporation or organization, as applicable, and has all
requisite power and authority to carry on its business to own and use its
properties. Each of the Company and its Subsidiaries

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is duly qualified to do business as a foreign entity and is in good standing (to
the extent such concept exists in the relevant jurisdiction) in each
jurisdiction in which the conduct of its business or its ownership or leasing of
property makes such qualification necessary, except to the extent any failure to
so qualify has not had and would not reasonably be expected to have a Material
Adverse Effect.
(b)    During the twelve (12) months preceding the Signing Date, neither the
Company nor any of its Subsidiaries has taken any action nor have any other
steps been taken or Actions commenced or, to the Company’s Knowledge, threatened
against any of them, for their winding up or dissolution or for any of them to
enter into any arrangement, scheme or composition for the benefit of creditors,
or for the appointment of a receiver, administrator, liquidator, trustee or
similar officer of any of them, or any of their respective properties, revenues
or assets.
3.2    Subsidiaries.  The Company has disclosed all of its subsidiaries required
to be disclosed (a) in an exhibit to its Annual Report on Form 10-K filed with
the SEC or (b) in its subsequent filings under the Exchange Act (the
“Subsidiaries”).  The Company owns, directly or indirectly, all of the capital
stock or other equity interests of each Subsidiary free and clear of any Liens,
and all of the issued and outstanding shares of capital stock of each Subsidiary
are validly issued and are fully paid and, if applicable in the relevant
jurisdiction, non-assessable, and free of preemptive and similar rights.
3.3    Capitalization.
(a)    The authorized share capital of the Company, immediately prior to the
Signing Date, consists of 100,000,000 Ordinary Shares, par value $0.01 per
share, of which 38,564,428 Ordinary Shares were issued and outstanding, and
10,000 Euro Deferred Shares, par value €22 per share, none of which were issued
and outstanding.  Under the Company’s Amended and Restated 2012 Long Term
Incentive Plan (the “Plan”), immediately prior to the Signing Date, (i) options
to acquire 5,311,125 Ordinary Shares have been granted and are outstanding and
(ii) 1,275,708 Ordinary Shares remained available for future issuance to
directors, employees and consultants of the Company, its Subsidiaries or the
Company’s Affiliates.  Since the Signing Date, the Company has not issued any
equity securities, other than those issued pursuant to the Plan.
(b)    Except as set forth in the Constitution, and other than the Ordinary
Shares reserved for issuance under the Plan, there are no outstanding options,
rights (including conversion or preemptive rights and rights of first refusal),
proxy or shareholder agreements, or agreements of any kind for the purchase or
acquisition from the Company or any of its Subsidiaries of any of its
securities, including the Shares.  No Person is entitled to preemptive rights,
rights of first refusal, rights of participation or similar rights with respect
to any securities of the Company or any of its Subsidiaries, including with
respect to the issuance of Shares contemplated hereby.  There are no voting
agreements, registration rights agreements or other agreements of any kind among
the Company or any of its

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Subsidiaries and any other Person relating to the securities of the Company or
any of its Subsidiaries, including the Shares.
(c)    All of the issued and outstanding Ordinary Shares have been duly
authorized and validly issued and are fully paid and were issued in compliance
with all applicable Laws concerning the issuance of securities.  The Shares have
been duly and validly authorized and, when issued and paid for pursuant to this
Agreement, will be validly issued, and fully paid. The Shares (i) will not be
subject to pre-emptive rights and (ii) shall be free and clear of all Liens,
except for restrictions on transfer imposed by applicable securities Laws or
contained herein.
(d)    Neither the Company nor any of its Subsidiaries owns or holds the right
to acquire any stock, partnership, interest, joint venture interest or other
equity ownership interest in any Person.
3.4    Authorization; Binding Obligations.  All corporate action on the part of
the Company and its board of directors necessary for the authorization of this
Agreement, the performance of all obligations of the Company hereunder at the
Closing and the issuance and delivery of the Shares pursuant hereto, has been
taken. No further action is required on the part of the Company, its board of
directors, or its shareholders prior to the Closing for the consummation of the
transactions contemplated by this Agreement.  This Agreement has been duly
executed and delivered by the Company and, assuming due authorization, execution
and delivery by the Subscriber, constitutes valid and binding obligations of the
Company enforceable in accordance with their terms, except (a) as limited by
applicable bankruptcy, insolvency, reorganization, fraudulent conveyance,
moratorium or other Laws of general application affecting enforcement of
creditors’ rights, (b) general principles of equity that restrict the
availability of equitable remedies and (c) to the extent that the enforceability
of indemnification provisions may be limited by applicable Laws.
3.5    Company SEC Documents; Financial Statements; Nasdaq.
(a)    Since December 31, 2014, the Company has timely filed with (or submitted
to) the SEC all of the reports and other documents required to be filed by (or
submitted to) it under the Exchange Act and Securities Act and any required
amendments to any of the foregoing (inclusive of any exhibits or other materials
incorporated by reference into any such filings and submissions, the “Company
SEC Documents”).  As of their respective filing dates, each of the Company SEC
Documents complied in all material respects with the requirements of the
Securities Act and the Exchange Act applicable to such Company SEC Documents,
and, when filed, no Company SEC Documents contained an untrue statement of a
material fact or omitted to state a material fact required to be stated therein
or necessary in order to make the statements therein, in light of the
circumstances under which they were made, not misleading.  None of the Company’s
Subsidiaries is subject to the periodic reporting requirements of the Exchange
Act. As of the date hereof, there are no outstanding or unresolved comments in
comment letters from the SEC staff with respect

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to any of the Company SEC Documents and the Company has not been notified that
any of the Company SEC Documents is the subject of ongoing SEC review or
outstanding investigation.
(b)    The financial statements of the Company included in the Company SEC
Documents when filed complied as to form in all material respects with
applicable accounting requirements and the published rules and regulations of
the SEC with respect thereto, have been prepared in accordance with GAAP applied
on a consistent basis during the periods involved (except as may be indicated in
the notes thereto) and fairly present in all material respects the financial
position of the Company as of the dates thereof and the results of its
operations and cash flows for the periods then ended.  Except for liabilities
incurred in the ordinary course of business subsequent to the date of the most
recent balance sheet contained in the Company SEC Documents, the Company has no
liabilities, whether absolute or accrued, contingent or otherwise, other than
(i) trade payables and accrued expenses incurred in the ordinary course of
business consistent with past practice, (ii) liabilities not required to be
reflected in the Company’s financial statements pursuant to GAAP and (iii) those
that would not, individually or in the aggregate, be material to the Company and
its Subsidiaries taken as a whole. Neither the Company nor any of its
Subsidiaries has or is subject to any “Off-Balance Sheet Arrangement” (as
defined in Item 303(a)(4)(ii) of Regulation S-K promulgated under the Securities
Act).
(c)    The Ordinary Shares are listed on the Nasdaq Global Select Market, and
the Company has not received any notification that, and has no Knowledge that,
Nasdaq is contemplating terminating such listing.
(d)    The Company’s registered public accounting firm is KPMG LLP. To the
Company’s Knowledge, KPMG LLP are independent public accountants with respect to
the Company within the meaning of the Securities Act and Exchange Act and the
applicable published rules and regulations thereunder.
3.6    Obligations to Related Parties. None of the members of the Company’s
board of directors, affiliates, senior executives, key employees or, to the
Company’s Knowledge, 5% shareholders of the Company or any members of their
immediate families, is indebted to the Company or party to a transaction with
the Company required to be disclosed in the Company SEC Documents under Item 404
of Regulation S-K that is not so disclosed.
3.7    Sarbanes-Oxley; Internal Accounting Controls. The Company is in
compliance with the requirements of the Sarbanes-Oxley Act of 2002, including
the rules and regulations of the SEC promulgated thereunder, and of the
Companies Act 2014, in each case as applicable to it as of the date hereof. The
Company maintains a system of internal accounting controls sufficient to provide
reasonable assurance that: (a) transactions are executed in accordance with
management’s general or specific authorizations, (b) transactions are recorded
as necessary to permit preparation of financial statements in

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conformity with GAAP and the Companies Act 2014 and to maintain asset
accountability, (c) access to assets is permitted only in accordance with
management’s general or specific authorization, and (d) the recorded
accountability for assets is compared with the existing assets at reasonable
intervals and appropriate action is taken with respect to any differences. The
Company has established disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the Company and designed such
disclosure controls and procedures to provide reasonable assurance that
information required to be disclosed by the Company in the reports it files or
submits under the Exchange Act is recorded, processed, summarized and reported,
within the time periods specified in the SEC’s rules and forms.
3.8    Compliance with Other Instruments.  The Company is not in violation or
default of any term of its Constitution and the Company and its Subsidiaries are
not in material breach of any Material Contract.  The execution, delivery, and
performance of and compliance with this Agreement, and the issuance and delivery
of the Shares pursuant hereto, will not, with or without the passage of time or
giving of notice, (i) conflict with or result in a violation of the
constitution, articles of association, charter, certificate of incorporation,
bylaws or other organizational or constitutive documents of the Company or any
of its Subsidiaries, in each case as in effect on Closing Date, (ii) result in
any violation of any Law or Order to which the Company, any of its Subsidiaries
or any of their respective assets is subject, (iii) (A) conflict with or result
in a breach, violation of, or constitute a default under, (B) give any third
party the right to modify, terminate or accelerate, or cause any modification,
termination or acceleration of, any obligation under or (C) require Consent
under, any Material Contract to which the Company or any of its Subsidiaries is
a party that has not been obtained or waived, or (iv) result in the creation of
any Lien upon any of the Company’s or any Subsidiary’s assets or capital stock,
except in the case of any of clauses (iii) and (iv) above, as would not
reasonably be expected to have a Material Adverse Effect.  Neither the
execution, delivery or performance of this Agreement by the Company, nor the
consummation by it of the obligations and transactions contemplated hereby
(including the issuance of the Shares) requires any Consent, other than
(i) filings required under applicable U.S. federal and state securities Laws and
(ii) the notification of the issuance and delivery of the Shares to Nasdaq.
3.9    Litigation.  There is no material: (i) Action pending or, to the
Company’s Knowledge, threatened, against the Company or any of its Subsidiaries
which, if determined adversely to the Company or any of its Subsidiaries would
have a Material Adverse Effect or (ii) Order in effect against the Company or
any of its Subsidiaries.
3.10    Compliance with Laws; Permits.  The Company and its Subsidiaries are
not, and since January 1, 2013 have not been, in violation in any material
respect of any applicable Law (including any Health Care Law) in respect of the
conduct of its business or the ownership of its properties.  The Company and
each of its Subsidiaries has all franchises, permits, licenses and any similar
authority necessary for the conduct of

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its business as now being conducted by it, except those the lack of which would
not reasonably be expected to have a Material Adverse Effect.
3.11    Offering Valid.  Assuming the accuracy of the representations and
warranties of the Subscriber contained in Section 4.5, the issuance and delivery
of the Shares will be exempt from the registration requirements of the
Securities Act, and will have been registered or qualified (or are exempt from
registration and qualification) under the registration, permit or qualification
requirements of all applicable securities Laws.  Neither the Company nor any
agent on its behalf has solicited or will solicit any offers to sell or has
offered to sell or will offer to sell all or any part of the Shares to any
person or persons so as to bring the issuance and delivery of such Shares by the
Company within the registration requirements of the Securities Act or the
securities Laws of Ireland.
3.12    Investment Company.  The Company is not, and after giving effect to the
transactions contemplated by the Transaction Agreements will not be, an
“investment company” or a company “controlled” by an “investment company,”
within the meaning of the Investment Company Act of 1940, as amended.
3.13    Absence of Changes. Since December 31, 2016, (a) the Company and each of
its Subsidiaries has conducted its business operations in the ordinary course of
business consistent with past practice, (b) there have been no events,
occurrences or developments that have had or would reasonably be expected to
have, either individually or in the aggregate, a Material Adverse Effect, (c)
the Company has not declared or made any dividend or distribution of cash,
shares of capital stock or other property to its shareholders or purchased,
redeemed or made any agreements to purchase or redeem any shares of its capital
stock (other than in connection with repurchases of unvested shares issued to
employees of the Company), and (d) the Company has not issued any equity
securities to any officer, director or Affiliate, except Ordinary Shares issued
in the ordinary course issued pursuant to existing Company equity incentive
plans or executive and director compensation arrangements.
3.14    Tax Matters.
(a)    (i) the Company and each of its Subsidiaries has timely prepared and
filed all federal and all other material Tax Returns required to have been filed
by each of them with all appropriate Tax Authorities and timely paid all Taxes
shown thereon (except for Taxes contested in good faith), (ii) all such Tax
Returns are true, correct and complete in all material respects and (iii) all
Taxes that the Company or any of its Subsidiaries is required to withhold or to
collect for payment have been duly withheld and collected and paid to the proper
Tax Authority or third party when due (except for Taxes contested in good
faith).
(b)     Neither the Company nor any of its Subsidiaries (i) has been a member of
an affiliated group filing a consolidated federal income U.S. Tax Return (other

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than a group the common parent of which was the Company or any of its
Subsidiaries) or (ii) has any material liability for the Taxes of any Person
(other than the Company or any of its Subsidiaries) under U.S. Treas. Reg. §
1.1502-6 (or any similar provision of state, local, or non-U.S. Law), as a
transferee or successor, by Contract, or otherwise (excluding Contracts entered
into in the ordinary course of business and not primarily related to Taxes).
(c)    Neither the Company nor any of its Subsidiaries has distributed stock of
another Person, or has had its stock distributed by another Person, in a
transaction that was purported or intended to be governed in whole or in part by
Section 355 or 361 of the Code.
(d)    Neither the Company nor any of its Subsidiaries is or has been a party to
any “listed transaction,” as defined in Section 6707A(c)(2) of the Code and U.S.
Treas. Reg. § 1.6011-4(b)(2).
(e)    Neither the Company nor any Subsidiary has ever been, nor will they be at
the Closing, a United States Real Property Holding Corporation within the
meaning of Section 897(c)(2) of the Code during the applicable period specified
in Section 897(c)(1)(A)(ii) of the Code.
3.15    Property. The Company does not own any real property. Except as would
not reasonably be expected to, individually or in the aggregate, have a Material
Adverse Effect, (a) the Company and each of its Subsidiaries has the right to
use or occupy the Leased Real Property under valid and binding Leases and (b)
the Company and its Subsidiaries have good and valid title to, or a valid
license to use or leasehold interest in, all of their respective material
tangible assets, free and clear of all Liens (other than Permitted Liens).
3.16    Employee Benefits Matters.
(a)    Except as would not reasonably be expected to have a Material Adverse
Effect, (i) each Employee Benefit Plan (and each related trust, insurance
Contract, or fund) has been maintained, funded and administered in accordance
with its terms and in compliance with the applicable requirements of Law,
including ERISA and the Code and other applicable Laws and (ii) all
contributions, distributions, reimbursements and premium payments due with
respect to each Employee Benefit Plan have been timely made or properly accrued.
Each Employee Benefit Plan that is intended to meet the requirements of a
“qualified plan” under Section 401(a) of the Code has received a favorable
determination letter (or may rely on a favorable opinion letter) issued by the
United States Internal Revenue Service and to the Company's Knowledge, nothing
has occurred that would reasonably be expected to have a material adverse effect
on the qualification of such Employee Benefit Plan.
(b)     Except as would not reasonably be expected to have a Material Adverse
Effect, (i) neither the Company nor any of its Subsidiaries maintains, sponsors,

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contributes to, has any obligation to contribute to, or has any current or
potential liability or obligation under or with respect to (A) a “defined
benefit plan” (as such term is defined in Section 3(35) of ERISA), (B) a
“multiple employer plan” (within the meaning of Section 210 of ERISA or Section
413(c) of the Code), (C) a “multiemployer plan” as defined in Section 3(37) of
ERISA, or (D) a “multiple employer welfare arrangement” (as such term is defined
in Section 3(40) of ERISA) or any equivalent plan to any of the foregoing in any
other jurisdiction, including but not limited to Ireland; (ii) no Employee
Benefit Plan provides and neither the Company nor any of its Subsidiaries has
any current or potential obligation to provide post-termination or
post-retirement health, life or other welfare benefits other than as required
under Section 4980B of the Code or any similar state Law; and (iii) neither the
Company nor any of its Subsidiaries has any current or potential liability or
obligation by reason of at any time being treated as a single employer under
Section 414 of the Code with any other Person.
(c)    Except as would not reasonably be expected to have a Material Adverse
Effect, (i) there have been no prohibited transactions (as defined in Section
406 of ERISA or Section 4975 of the Code) and no breach of fiduciary duty (as
determined under ERISA) with respect to any Employee Benefit Plan, (ii) the
Company and its Subsidiaries have, for purposes of each Employee Benefit Plan,
correctly classified those individuals performing services for the Company or
any of its Subsidiaries as employees or non-employees, and (iii) there do not
exist any pending or, to the Company’s Knowledge, threatened claims (other than
routine undisputed claims for benefits) or Actions with respect to any Employee
Benefit Plan.
(d)    The transactions contemplated by the Transaction Agreements will not
(either alone or in combination with another event) (i) cause the acceleration
of vesting in, or payment of, any material benefits or compensation under any
Employee Benefit Plan, (ii) require the funding of any material amount of
compensation or benefits due to any manager, employee, officer, director,
shareholder or other service provider (whether current, former or retired) of
the Company or any of its Subsidiaries or their beneficiaries and, (iii)
otherwise materially accelerate or materially increase any liability or
obligation under any Employee Benefit Plan.
3.17    Labor Matters.
(a)    Neither the Company nor any of its Subsidiaries is a party to or bound by
any collective bargaining agreement or other Contract or relationship with any
union, labor organization, or other collective bargaining representative. There
are no strikes, work stoppages or any other material labor disputes against the
Company or any of its Subsidiaries pending or, to the Company’s Knowledge,
threatened, and no such disputes have occurred since January 1, 2015. No union
organization or decertification activities are underway or, to the Company’s
Knowledge, threatened with respect to employees of the Company or any of its
Subsidiaries.

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(b)    Each of the Company and its Subsidiaries is, and at all times since
January 1, 2015, has been in compliance in all material respects with all
applicable Laws and codes of conduct respecting employment and employment
practices, including provisions thereof relating to terms and conditions of
employment, wages and hours, overtime, classification of employees and
independent contractors, immigration, and the withholding and payment of social
security and other employment Taxes.
(c)    Since January 1, 2015, neither the Company nor any of its Subsidiaries
has implemented any plant closing or layoff of employees that could implicate
the WARN Act and result in material liability to the Company and its
Subsidiaries, taken as a whole.
3.18    Intellectual Property.
(a)    The Company owns all right, title and interest in and to, or has the
valid and enforceable right to use pursuant to a written Contract, all
Intellectual Property used in the conduct of the business of the Company as
currently conducted (collectively, the “Company Intellectual Property”) free and
clear of any Liens, except Permitted Liens, except where the failure to be in
such compliance would reasonably be expected to have a Material Adverse Effect,
and, to the Company’s Knowledge, the owners of any Intellectual Property
licensed to Company have taken necessary actions to maintain and protect such
Intellectual Property, except where the failure to be in such compliance would
reasonably be expected to have a Material Adverse Effect.
(b)    To the Company’s Knowledge, (i) the Company has not infringed,
misappropriated, or otherwise violated, or is not currently infringing,
misappropriating, or otherwise violating, any Intellectual Property of any other
Person and there are no Actions pending or threatened alleging any of the
foregoing, including any unsolicited offers for the Company to obtain a license
to any Intellectual Property of another Person, and (ii) no Person is
infringing, misappropriating or violating the rights of the Company with respect
to any Company Intellectual Property, except where it is not reasonably expected
to have a Material Adverse Effect.
3.19    FDA and Regulatory Matters.
(a)    There is no actual or, to the Company’s Knowledge, threatened enforcement
action or investigation by the FDA or any other Governmental Authority, which,
if determined adversely to the Company or any of its Subsidiaries would have a
Material Adverse Effect. The Company has no Knowledge or reason to believe that
the FDA or any Governmental Authority is considering such action. The operation
of the business of the Company, including the manufacture, import, export,
testing, development, processing, packaging, labeling, storage, marketing,
sales, and distribution of the Company’s product candidates is, and at all times
has been, in material compliance with all applicable laws and permits, or within
the FDA’s exercise of enforcement discretion.

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(b)     All material reports, documents, claims, permits and notices required to
be filed with, maintained for or furnished to the FDA or any Governmental
Authority have been so filed, maintained or furnished by the Company. All such
reports, documents, claims and notices were complete and accurate in all
material respects on the date filed or furnished (or were corrected in or
supplemented by a subsequent filing), such that no liability exists with respect
to such filing, and remain complete and accurate.
(c)    The Company has not received any FDA Form 483, notice of adverse finding,
warning letters, untitled letters or other correspondence or notice from the FDA
or any Governmental Authority (i) alleging or asserting material noncompliance
with any applicable laws or permits and the Company has no Knowledge or reason
to believe that the FDA or any Governmental Authority is considering such action
or (ii) materially contesting the pre-market clearance or approval of, the uses
of or the labeling or promotion of any of the Company’s product candidates.
(d)    Each of the Company’s product candidates subject to the FDCA that has
been developed, manufactured, tested or distributed by or on behalf of the
Company is being or has been developed, manufactured, tested or distributed in
compliance with all material applicable requirements under the FDCA and
comparable laws in any non-U.S. jurisdiction, including those relating to
investigational use, pre-market clearance or approval, biologics licensing,
registration and listing, good manufacturing practices, labeling, advertising,
record keeping and filing of required reports.
(e)    The preclinical tests and clinical trials conducted by the Company, and
to Company’s Knowledge the clinical trials conducted by third parties, in each
case described in, or the results of which are referred to in, the Company SEC
Documents, were, and if still pending, are being, conducted in all material
respects in accordance with protocols and procedures filed with the appropriate
regulatory authorities for each such trial; each description of the results of
such preclinical tests and clinical trials contained in the Company SEC
Documents is accurate and complete in all material respects and fairly presents
the data derived from such preclinical tests and clinical trials, and the
Company has no knowledge of any other studies or tests the results of which are
inconsistent with, or otherwise call into question, the results described or
referred to in the Company SEC Documents.
3.20    Environmental Matters. Except as would not reasonably be expected to,
individually or in the aggregate, have a Material Adverse Effect: (a) no notice,
notification, demand, request for information, citation, summons, complaint or
Order has been received since January 1, 2015 by, and no Action is pending or,
to the Company’s Knowledge, threatened by any Person against, the Company or any
of its Subsidiaries, and no penalty has been assessed against the Company or any
of its Subsidiaries, in each case, with respect to any matters relating to or
arising out of any Environmental Law and (b) the Company and its Subsidiaries
are, and since January 1, 2015 have been, in compliance in all material respects
with all applicable Environmental Laws, including any Consent required by
Environmental Laws.

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3.21    Insurance. Except as has not had, and would not reasonably be expected
to have, individually or in the aggregate, a Company Material Adverse Effect,
(a) all insurance policies (“Policies”) with respect to the business and assets
of the Company and its Subsidiaries are in full force and effect, (b) neither
the Company nor any of its Subsidiaries is in breach or default, and neither the
Company nor any of its Subsidiaries has taken any action or failed to take any
action that, with notice or the lapse of time, would constitute such a breach or
default, or permit termination or modification of any of the Policies, and (c)
the Company and its Subsidiaries have not received any written notice of
cancellation or threatened cancellation of any of the Policies or of any claim
pending regarding the Company or any of its Subsidiaries under any of such
Policies as to which coverage has been questioned, denied or disputed by the
underwriters of such Policies. The Company and its Subsidiaries maintain
insurance with reputable insurers in such amounts and against such risks as is
customary for the industries in which it and its Subsidiaries operate and as the
management of the Company has in good faith determined to be prudent and
appropriate.
3.22    Takeover Protections. The Company and its board of directors have taken
all necessary action, if any, in order to render inapplicable any control share
acquisition, business combination, poison pill (including any distribution under
a rights agreement) or other similar anti-takeover provision under the
Constitution or the laws of Ireland that is or would reasonably be expected to
become applicable to Subscriber as a result of the transactions contemplated by
this Agreement, including, without limitation, the Company’s issuance of the
Shares and the Subscriber’s ownership of the Shares.
3.23    Anti-Corruption and Anti-Bribery Laws. Neither the Company and its
Subsidiaries, nor, to the Company’s Knowledge, any of their respective director,
officer, agent, employee or other authorized person acting on behalf of the
Company is aware of or has taken any action, directly or indirectly, that could
result in a violation or a sanction for violation by such persons of the Foreign
Corrupt Practices Act of 1977, the Prevention of Corruption Acts 1899 to 2010 or
the U.K. Bribery Act 2010, each as may be amended, or similar law of any other
relevant jurisdiction, or the rules or regulations thereunder; and the Company
has instituted and maintain policies and procedures to ensure compliance
therewith. No part of the proceeds from the issuance and delivery of the Shares
will be used, directly or indirectly, in violation of the Foreign Corrupt
Practices Act of 1977, the Prevention of Corruption Acts 1899 to 2010 or the
U.K. Bribery Act 2010, each as may be amended, or similar law of any other
relevant jurisdiction, or the rules or regulations thereunder.
3.24    Economic Sanctions. None of the Company, any of its Subsidiaries or, to
the Knowledge of the Company, any director, officer, agent, employee, Affiliate
or representative or other authorized person acting on behalf of the Company or
any of its subsidiaries is a Person currently the subject or target of any
sanctions administered or enforced by the United States Government or any
Governmental Authority in Ireland or

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elsewhere including, without limitation, the U.S. Department of the Treasury’s
Office of Foreign Assets Control (“OFAC”), the United Nations Security Council
(“UNSC”), the European Union, Her Majesty’s Treasury (“HMT”), or other relevant
sanctions authority (collectively, “Sanctions”), nor is the Company located,
organized or resident in a country or territory that is the subject of
Sanctions; and the Company will not directly or indirectly use the proceeds of
the issuance of the Shares, or lend, contribute or otherwise make available such
proceeds to any Subsidiaries, joint venture partners or other Person, to fund
any activities of or business with any Person, or in any country or territory,
that, at the time of such funding, is the subject of Sanctions or in any other
manner that will result in a violation by any Person (including any Person
participating in the transaction) of Sanctions. Within the past five (5) years,
to the Knowledge of the Company, it has neither been the subject of any
governmental investigation or inquiry regarding compliance with Sanctions nor
has it been assessed any fine or penalty in regard to compliance with Sanctions.
3.25    Money Laundering.  The operations of the Company and its Subsidiaries
are and have been conducted at all times in compliance with applicable financial
record-keeping and reporting requirements of the Currency and Foreign
Transactions Reporting Act of 1970 and The Criminal Justice (Money Laundering
and Terrorist Financing ) Act 2010, each as amended, and applicable money
laundering statutes and applicable rules and regulations thereunder
(collectively, the “Money Laundering Laws”), and no action, suit or proceeding
by or before any court or governmental agency, authority or body or any
arbitrator involving the Company with respect to the Money Laundering Laws is
pending or, to the Company’s Knowledge, threatened.
3.26    Certain Fees. No person or entity will have, as a result of the
transactions contemplated by this Agreement, any valid right, interest or claim
against or upon the Company or the Subscriber for any commission, fee or other
compensation pursuant to any agreement, arrangement or understanding entered
into by or on behalf of the Company, with respect to the issuance and delivery
of the Shares.
3.27    Disclosure. None of the Company SEC Documents contain any untrue
statement of a material fact or omit a material fact necessary to make each
statement contained therein, in light of the circumstances in which they were
made, not misleading.
3.28    No “Bad Actor” Disqualification. The Company has conducted a factual
inquiry including the procurement of relevant questionnaires from each of the
Company’s executive officers and directors or other means to determine whether
any of the Company’s executive officers or directors is subject to any of the
“bad actor” disqualifications described in Rule 506(d)(1)(i) to (viii) under the
Securities Act (“Disqualification Events”). Neither the Company, nor, to the
Company’s Knowledge, after conducting such factual inquiries, any other Covered
Person, is subject to Disqualification Events, except for a Disqualification
Event covered by Rule 506(d)(2) or (d)(3) under the Securities Act. The Company
has complied, to the extent applicable, with any disclosure

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obligations under Rule 506(e) under the Securities Act. “Covered Persons” are
those persons specified in Rule 506(d)(1) under the Securities Act, including
the Company; any predecessor or affiliate of the Company; any director,
executive officer, other officer participating in the offering, general partner
or managing member of the Company; any beneficial owner of 20% or more of the
Company’s outstanding voting equity securities, calculated on the basis of
voting power; any promoter (as defined in Rule 405 under the Securities Act)
connected with the Company in any capacity at the time of the issuance and
delivery of the Shares; and any person that has been or will be paid (directly
or indirectly) remuneration for solicitation of subscribers in connection with
the issuance and delivery of the Shares (a “Solicitor”), any general partner or
managing member of any Solicitor, and any director, executive officer or other
officer participating in the offering of any Solicitor or general partner or
managing member of any Solicitor.
4.    Representations and Warranties of the Subscriber.  The Subscriber hereby
represents and warrants as of the date hereof to the Company as follows:

4.1    Organization; Good Standing.  The Subscriber is a limited liability
company duly organized, validly existing and in good standing under the laws of
the State of Delaware.  The Subscriber has or will have all requisite power and
authority to enter into this Agreement, to subscribe for the Shares and to
perform its obligations under and to carry out the other transactions
contemplated by this Agreement, and no further approval or authorization by any
of its members or other equity owners, as the case may be, is required.
4.2    Requisite Power and Authority.  The Subscriber has all necessary power
and authority to execute and deliver this Agreement and all action on the
Subscriber’s part required for the lawful execution and delivery of this
Agreement has been taken.  This Agreement been duly and validly executed and
delivered by the Subscriber and its obligations hereunder, assuming due
authorization, execution and delivery by the Company, are valid and binding
obligations of the Subscriber, enforceable in accordance with their terms,
except (a) as limited by applicable bankruptcy, insolvency, reorganization,
moratorium or other Laws of general application affecting enforcement of
creditors’ rights, (b) as limited by general principles of equity that restrict
the availability of equitable remedies, and (c) to the extent that the
enforceability of indemnification provisions may be limited by applicable Laws.
4.3    No Conflicts.  The execution, delivery and performance of this Agreement
and compliance with the provisions thereof by the Subscriber will not, with or
without the passage of time or giving of notice: (i) conflict with or result in
a violation of the certificate of incorporation, bylaws, or other organizational
or constitutive documents of the Subscriber as in effect on the Closing Date,
(ii) result in any violation of any Law or Order to which the Subscriber or any
of its assets is subject, (iii) (A) conflict with or result in a breach,
violation of, or constitute a default under, or (B) give any third party the
right to modify, terminate or accelerate, or cause any modification, termination
or acceleration

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of, any obligation under any Contract to which the Subscriber is a party, or
(iv) result in the creation of any Lien upon any of the Subscriber’s assets or
equity interests, except in the case of any of clauses (ii), (iii) and
(iv) above, as would not reasonably be expected to materially impair of the
ability of the Subscriber to perform its obligations under this Agreement and
the transactions contemplated hereby in any material respect.
4.4    No Governmental Authority or Third Party Consents.  No Consent is
required to be obtained or filed by the Subscriber in connection with the
authorization, execution and delivery of any of this Agreement or with the
subscription for the Shares.
4.5    Investment Representations.  The Subscriber hereby represents and
warrants as follows:
(a)    Subscriber Acknowledgements. The Subscriber acknowledges that the Shares
have not been registered under the Securities Act or under any state or foreign
securities laws.  The Subscriber (i) acknowledges that it is acquiring the
Shares pursuant to an exemption from registration under the Securities Act
solely for investment with no present intention to distribute any of the Shares
to any person in violation of applicable securities Laws, (ii) will not Dispose
of any of the Shares, except in compliance with the registration requirements or
exemption provisions of the Securities Act and any other applicable securities
Laws, (iii) does not presently have any agreement, plan or understanding,
directly or indirectly, with any Person to distribute or effect any distribution
of any of the Shares (or any securities which are derivatives thereof) to or
through any Person, (iv) is not a registered broker-dealer under Section 15 of
the Exchange Act or an entity engaged in a business that would require it to be
so registered as a broker-dealer and (v) is not purchasing the Shares as a
result of any advertisement, article, notice or other communication regarding
Shares published in any newspaper, magazine or similar media or broadcast over
television or radio or presented at any seminar or any other general
advertisement.
(b)    Status. At the time the Subscriber was offered the Shares, it was, and as
of the date hereof is, an “accredited investor” (as that term is defined by
Rule 501 of the Securities Act) and (i) has been furnished with or has had full
access to all the information that it considers necessary or appropriate to make
an informed investment decision with respect to the Shares, (ii) has had an
opportunity to discuss with management of the Company the intended business and
financial affairs of the Company and, in connection therewith, obtained
information necessary to verify any information furnished to it or to which it
had access (it being agreed and understood that this clause does not affect the
Company’s representations and warranties contained in Section 3) and (iii) can
bear the economic risk of (A) an investment in the Shares indefinitely and (B) a
total loss in respect of such investment.  The Subscriber has such knowledge and
experience in business and financial matters so as to enable it to understand
and evaluate the risks of and form an investment decision with respect to its
investment in the Shares and to protect its own interest in

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connection with such investment. The Subscriber understands that there is no
assurance that any exemption from registration under the Securities Act will be
available to transfer the Shares and that, even if available, such exemption may
not allow the Subscriber to transfer all or any portion of the Shares under the
circumstances, in the amounts or at the times the Subscriber might propose.
(c)    Ownership.  Neither the Subscriber nor any of its Controlled Affiliates
is the owner of record or the beneficial owner of Ordinary Shares or Ordinary
Share Equivalents.
4.6    Brokers and Finders. No Person will have, as a result of the transactions
contemplated by this Agreement, any valid right, interest or claim against or
upon the Company or the Subscriber for any commission, fee or other compensation
pursuant to any agreement, arrangement or understanding entered into by or on
behalf of the Subscriber.
4.7    United States Investor. The Subscriber is a United States person (as
defined by Section 7701(a)(30) of the Code).
5.    Covenants and Agreements.

5.1    Transfer Restrictions. 
(a)    The Subscriber understands that the Shares shall be subject to
restrictions on resale pursuant to applicable securities Laws and that any
certificates representing the Shares or the applicable balance account of the
Subscriber with the Company’s Transfer Agent shall bear transfer restrictions
with the effect of the following applicable legends:
(i)“THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED.  THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN
THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE SECURITIES
UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL (WHICH COUNSEL SHALL BE
REASONABLY SATISFACTORY TO PROTHENA CORPORATION PLC) THAT SUCH REGISTRATION IS
NOT REQUIRED OR UNLESS SOLD PURSUANT TO RULE 144 OF THE SECURITIES ACT.”; and
(ii)any legend required by other applicable securities Laws.
(b)    Subject to the restrictions set forth in Section 5.2 below, the Shares
shall not bear the transfer restrictions set forth in Section 5.1(a)(i):
(i) following a sale of Shares pursuant to an effective registration statement
covering the resale of such Shares, (ii) following any sale of Shares pursuant
to Rule 144 promulgated under the Securities Act (“Rule 144”) (or any successor
provision then in effect), or (iii) if such legend is not required

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under applicable requirements of the Securities Act (including judicial
interpretations and pronouncements issued by the staff of the Commission). In
addition, the Shares shall not bear the transfer restrictions set forth in
Section 5.1(a)(ii) following a sale of Shares if, following a sale, the Shares
are not required to carry a legend pursuant to such applicable securities Laws
referred to in Section 5.1(a)(ii). Notwithstanding the foregoing, the Company
shall direct the Transfer Agent to remove the transfer restriction set forth in
Section 5.1(a)(i) applicable to the Shares upon the written request of the
Subscriber, within two Business Days of the Company’s receipt of such request,
at such time as the Shares may be transferred without the requirement that the
Company be in compliance with the public information requirements and without
volume or manner-of-sale restrictions under Rule 144. The Subscriber, or if the
Transfer Agent requires, the Company, shall provide such opinions of counsel
(which counsel shall be reasonably satisfactory to the Company) reasonably
requested by the Transfer Agent in connection with the removal of legends
pursuant to this Section 5.1(b). In addition, if the Subscriber requests that
the Transfer Agent transfer the Shares, the Subscriber shall provide such other
documentation, including for the avoidance of doubt a duly completed stock
transfer form, reasonably requested by the Transfer Agent in connection with the
onward transfer of the Shares at least two Business Days prior to the intended
transfer date.
5.2    Standstill. During the Standstill Period, the Subscriber, or any of its
Controlled Affiliates, shall not:
(i)without the express written consent of the Company, directly or indirectly
acquire any additional equity securities (including Ordinary Shares and Ordinary
Share Equivalents) of the Company, if after giving effect to such acquisition
the Subscriber, or any of its Controlled Affiliates, would, directly or
indirectly, own more than 9.9% of the then outstanding share capital of the
Company;
(ii)directly or indirectly encourage or support a tender, exchange or other
offer or proposal by a Third Party;
(iii) publicly propose (x) any merger, consolidation, business combination,
tender or exchange offer, purchase of the Company’s assets or businesses, or
similar transaction involving the Company or (y) any recapitalization,
restructuring, liquidation or other extraordinary transaction with respect to
the Company;
(iv)directly or indirectly, seek to have called any meeting of the shareholders
of the Company, propose or nominate for election to the Company’s board of
directors any person whose nomination has not been approved by a majority of the
Company’s board of directors or cause to be voted in favor of such person for
election to the Company’s board of directors any Ordinary Shares of the then
outstanding share capital of the Company or Ordinary Share Equivalents other
than as contemplated by Section 5.4;

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(v)directly or indirectly, solicit proxies or consents or become a participant
in a solicitation (as such terms are defined in Regulation 14A under the
Exchange Act) in opposition to the recommendation of a majority of the Company’s
board of directors with respect to any matter, or seek to advise or influence
any Third Party, with respect to voting of any Ordinary Shares of the then
outstanding share capital of the Company or Ordinary Share Equivalents;
(vi)deposit any Ordinary Shares of the then outstanding share capital of the
Company or Ordinary Share Equivalents in a voting trust or subject any Ordinary
Shares of the then outstanding share capital of the Company or Ordinary Share
Equivalents to any arrangement or agreement with respect to the voting of such
Ordinary Shares of the then outstanding share capital of the Company or Ordinary
Share Equivalents other than as contemplated by Section 5.4;
(vii)act in concert with any Third Party to take any action in clauses
(i) through (vi) above, or form, join or in any way participate in a
“partnership, limited partnership, syndicate, or other group” with any Third
Party within the meaning of Section 13(d)(3) of the Exchange Act with respect to
the equity securities of the Company;
(viii)enter into discussions, negotiations, arrangements or agreements with any
Third Party relating to the foregoing actions referred to in clauses (i) through
(vi) above; provided, however, that the mere voting in accordance with
Section 5.4 of any voting securities of the Company held by the Subscriber, its
executive officers or directors, or its Controlled Affiliates shall not
constitute a violation of any of clauses (i) through (vii) above.
Notwithstanding the foregoing, (A) none of the Subscriber’s executive officers
or directors shall be restricted from purchasing Ordinary Shares or Ordinary
Share Equivalents for his or her personal account (other than through a tender
or exchange offer), tendering his or her Ordinary Shares or Ordinary Share
Equivalents into a Third Party tender or exchange offer, voting his or her
Ordinary Shares, or Ordinary Share Equivalents in any way he or she determines,
or depositing his or her Ordinary Shares or Ordinary Share Equivalents into a
voting trust or subjecting them to any arrangement or agreement with respect to
the voting of such Ordinary Shares or Ordinary Share Equivalents; (B) if any
executive officer or director of the Subscriber serves as a member of the
Company’s board of directors, any action he or she takes in the performance of
his or her duties as a member of the Company’s board of directors shall not be
deemed to violate this Section 5.2, except if he or she takes such action at the
direction of Subscriber or an Affiliate thereof; and (C) the foregoing
restrictions in this Section 5.2 shall not (i) restrict the Subscriber or its
subsidiaries from engaging in private, non-public discussions regarding a
transaction otherwise prohibited by this Section 5.2 with the Company’s board of
directors; and (ii) prohibit the Subscriber or its subsidiaries from acquiring
securities of, or from entering into any merger or other business combination
with, another Person that beneficially owns securities of the Company.
5.3    Lock-Up. During the Lock-Up Period, the Subscriber shall not and shall
cause its Controlled Affiliates not to, without the prior consent of the
Company, directly or indirectly, Dispose of (a) any of the Shares, or any
Ordinary Shares or Ordinary Share

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Equivalents beneficially owned by the Subscriber or any of its Controlled
Affiliates as of the Signing Date, together with any Ordinary Share, or Ordinary
Share Equivalents issued in respect thereof as a result of any stock split,
stock dividend, share exchange, merger, consolidation or similar
recapitalization, and (b) any Ordinary Shares or Ordinary Share Equivalents
issued as (or issuable upon the exercise of any warrant, right or other security
that is issued as) a dividend or other distribution with respect to, or in
exchange or in replacement of, the Ordinary Shares or Ordinary Share Equivalents
described in clause (a) of this sentence, but excluding Ordinary Shares acquired
after the Closing Date; provided, however, that the foregoing shall not prohibit
the Subscriber or its Controlled Affiliates from Transferring Ordinary Shares or
Ordinary Share Equivalents (i) to a Permitted Transferee, (ii) to the Company,
(iii) with the prior written consent of the Company, (iv) if the Subscriber’s
auditors determine that the Company’s financial results must be consolidated
with the Subscriber’s in the Subscriber’s financial statements pursuant to the
principles of consolidation under GAAP, Dispositions made in order to reduce the
Subscriber’s ownership of the Company’s voting securities to such amount as
would not require such consolidation under GAAP, or (v) pursuant to a bona fide
third party tender offer, merger, consolidation or other similar transaction
made to holders of the Shares involving a change of control of the Company;
provided further, that in the event that the tender offer, merger,
consolidation, scheme of arrangement or other such transaction is not
consummated, the Subscriber shall remain subject to the restrictions contained
herein.
5.4    Voting of Securities.  During the Standstill Period, in any vote of the
shareholders of the Company (including, without limitation, with respect to the
election of directors), except as provided by Section 5.5, the Subscriber shall
vote all voting securities of the Company as to which it is entitled to vote in
accordance with the recommendation of a majority of the Company’s board of
directors.
5.5    Change of Control. Notwithstanding Section 5.4, the Subscriber may vote,
or execute a written consent with respect to, any or all of the voting
securities of the Company as to which they are entitled to vote or execute a
written consent, as they may determine in their sole discretion with respect to
any transaction the consummation of which would result in a Change of Control of
the Company.
5.6    Offering Lock-Up. The Subscriber shall, if requested by the Company and
an underwriter of Ordinary Shares or Ordinary Share Equivalents in connection
with any public offering involving an underwriting of Ordinary Shares or
Ordinary Share Equivalents, agree not to Dispose of any Ordinary Shares or
Ordinary Share Equivalents for a specified period of time, such period of time
not to exceed 90 days (a “Lock-Up Agreement”). Any Lock-Up Agreement shall be in
writing in a form reasonably satisfactory to the Company and the
underwriter(s) in such offering. The Company may impose stop transfer
instructions with respect to the Ordinary Shares or Ordinary Share Equivalents
subject to the foregoing restrictions until the end of the specified period of
time. The foregoing provisions of this Section 5.6 shall not apply (a) if the
Subscriber owns less

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than 10% of Ordinary Shares of the outstanding share capital of the Company, or
(b) to the sale of any shares to an underwriter pursuant to an underwriting
agreement, and shall be applicable to the Subscriber only if all officers and
directors are subject to the same restrictions.
5.7    Further Assurances.  Subject to the terms and conditions of this
Agreement, each of the Company and the Subscriber agrees to use its reasonable
best efforts to take, or cause to be taken, all actions, and to do, or cause to
be done, and assist the other party hereto in doing, all things reasonably
necessary, proper or advisable to obtain satisfaction of the conditions
precedent to the consummation of the transactions contemplated at the Closing,
including:  (a) obtaining all necessary Consents and the making of all filings
and the taking of all steps as may be necessary, including convening any
prerequisite meetings of bodies of the Company, to obtain a required Consent or
avoid an Action by any Governmental Authority, (b) the defending of any Actions
challenging this Agreement or any other Transaction Agreements or the
consummation of the transactions contemplated hereby or thereby, including
seeking to have any stay or temporary restraining order entered by any court or
other Governmental Authority vacated or reversed, and (c) the execution and
delivery of any additional instruments necessary to consummate the transactions
contemplated by, and to fully carry out the purposes of, this Agreement and the
other Transaction Agreements.
5.8    Securities Law Disclosure; Publicity.  No public release or announcement
concerning the transactions contemplated hereby or by any other Transaction
Agreement, including the public filing of any Transaction Agreement pursuant to
applicable securities Laws, shall be issued by the Company or the Subscriber
without the prior consent of the Company (in the case of a release or
announcement by the Subscriber) or the Subscriber (in the case of a release or
announcement by the Company) (which consents shall not be unreasonably withheld,
conditioned or delayed), except for any such release or announcement as may be
required by securities Law or other applicable Law or the applicable rules or
regulations of any securities exchange or securities market, in which case the
Company or the Subscriber, as the case may be, shall allow the Subscriber or the
Company, as applicable, reasonable time to comment on such release or
announcement in advance of such issuance and the disclosing party shall consider
the other party’s comments in good faith.  Following execution and delivery of
this Agreement, the Company shall issue a press release substantially in the
form set forth in Exhibit A.
5.9    Integration.  The Company shall not sell, offer for sale or solicit
offers to buy or otherwise negotiate in respect of any security (as defined in
Section 2 of the Securities Act) that would be integrated with the offer or sale
of the Shares in a manner that would require the registration under the
Securities Act of the Shares to be issued to the Subscriber hereunder for
purposes of the rules and regulations of any of the following markets or
exchanges on which the Ordinary Shares of the Company is listed or quoted for
trading on the date in question (including the OTC Markets Group, the OTC
Bulletin Board,

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the Nasdaq Capital Market, the Nasdaq Global Market, the Nasdaq Global Select
Market, the NYSE American or the New York Stock Exchange), such that it would
require shareholder approval prior to the closing of such other transaction
unless shareholder approval is obtained before the closing of such subsequent
transaction.
5.10    Notification. After the date hereof and prior to the Closing Date, the
Company shall promptly deliver to the Subscriber a written notice of any event
or development that would, or could reasonably be expected to, result in any
condition to Closing set forth in Section 6, not to be satisfied.
5.11    Registration Rights.  The Company covenants and agrees as follows:
(a)    Within 30 days following a written request by the Subscriber at any time
after the expiration of the Lock-Up Period (or any earlier termination or waiver
by the Company thereof), or such earlier time as the Company in its sole
discretion may agree in writing, the Company shall file a prospectus supplement
or a registration statement to register the resale of the Registrable Shares on
a Form S-3ASR or Form S-3 registration statement under the Securities Act and
use reasonable best efforts to have such registration statement declared
effective, if the Company is not eligible to use Form S-3ASR, and maintain the
effectiveness of such registration statement for a period ending on the date the
Subscriber no longer holds Registrable Shares.
(b)    All expenses incurred in connection with registrations, filings or
qualifications pursuant to this Section 5.11, including all registration, filing
and qualification fees; printers’ and accounting fees; and fees and
disbursements of counsel for the Company, shall be borne and paid by the
Company. All (i) underwriting discounts and selling commission, but only to the
extent that the Subscriber intends to distribute the Registrable Shares by means
of an underwriting, (ii) fees and disbursements of counsel for Subscriber and
(iii) transfer taxes incurred in connection with the sale of any Shares by
Subscriber (collectively “Selling Expenses”) shall be borne by Subscriber. For
the avoidance of doubt, the Company shall not bear any Selling Expenses in
connection with its obligations under this Agreement.
(c)    For the purposes of this Section 5.11,
(i)“Losses” means any loss, damage, claim or liability (joint or several) to
which a party hereto may become subject under the Securities Act, the Exchange
Act, or other federal or state law, insofar as such loss, damage, claim or
liability arises out of and is based upon: (A) any untrue statement or alleged
untrue statement of a material fact contained in any registration statement of
the Company registering the resale of the Registrable Shares, including any
preliminary prospectus or final prospectus contained therein or any amendments
or supplements thereto or (B) an omission or alleged omission to state in such
registration statement a material fact required to be stated therein, or
necessary to make the statements therein not misleading.

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(ii)“Registrable Shares” means the Shares held by Subscriber, including, without
limitation, any Ordinary Shares paid, issued or distributed in respect of any
such Shares by way of stock dividend, stock split or distribution, or in
connection with a combination of shares, recapitalization, reorganization,
merger or consolidation, or issued in exchange for or in replacement of the
Shares, or otherwise, but excluding Ordinary Shares acquired after the Closing
Date, provided, however, that the Shares will not be “Registrable Shares”
(A) after the Shares have been sold pursuant to an effective registration
statement or in compliance with Rule 144 or other exemptions from registration
or (B) when the Shares held by the Subscriber could, in the opinion of counsel
satisfactory to the Company, be sold by the Subscriber in a single transaction
without the volume and manner of sale limitations under Rule 144 unless the
Subscriber has taken action, without the consent or agreement of the Company,
subsequent to the date hereof to cause such Shares not to be eligible for such
sale under Rule 144.
(d)    With a view to making available to the Subscriber the benefits of
Rule 144, during the 12-month period following the Closing Date, the Company
covenants that it will use reasonable best efforts to (i) file in a timely
manner all reports and other documents required, if any, to be filed by it under
the Securities Act and the Exchange Act and the rules and regulations adopted
thereunder and (ii) make available information necessary to comply with Rule 144
with respect to resales of the Shares under the Securities Act, at all times, to
the extent required from time to time to enable the Subscriber to resell Shares
without registration under the Securities Act within the limitation of the
exemptions provided by Rule 144 (if available with respect to resales of the
Shares), as such rule may be amended from time to time.
(e)    To the extent permitted by law, the Company will indemnify and hold
harmless the Subscriber, and the partners, members, officers and directors of
the Subscriber (collectively, “Subscriber Indemnified Parties”), against any
Losses, and the Company will pay to the Subscriber Indemnified Parties any legal
or other reasonable and documented expenses incurred thereby in connection with
investigating or defending any claim or proceeding from which Losses may result,
as such expenses are incurred; provided, however, that the indemnity agreement
contained in this Section 5.11(e) shall not apply (i) to amounts paid in
settlement of any such claim or proceeding if such settlement is effected
without the consent of the Company, which consent shall not be unreasonably
withheld, (ii) any Losses to the extent that they arise out of or are based upon
actions or omissions made in reliance upon and in conformity with written
information furnished by or on behalf of any Subscriber Indemnified Party
expressly for use in connection with such registration or (iii) to the extent it
is judicially determined that any Subscriber Indemnified Party is not entitled
to indemnification hereunder.
(f)    Promptly after receipt by the Subscriber under this Section 5.11 of
notice of the commencement of any action (including any governmental action) for
which a Subscriber Indemnified Party may be entitled to indemnification
hereunder, the Subscriber Indemnified Party will, if a claim in respect thereof
is to be made against the Company under

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this Section 5.11(f), give the Company notice of the commencement thereof.  The
Company shall have the right to participate in such action and, to the extent
the Company so desires, and to assume the defense thereof with counsel mutually
satisfactory to the Subscriber Indemnified Parties and the Company; provided,
however, that the Subscriber Indemnified Parties shall have the right to retain
one separate counsel for all such Subscriber Indemnified Parties, with the
reasonable and documented fees and expenses to be paid by the Company, if
representation of the Subscriber by the counsel retained by the Company would be
inappropriate due to actual or potential conflict of interest between the
Subscriber Indemnified Parties and the Company.  The failure to give notice to
the Company within a reasonable time of the commencement of any such action
shall relieve the Company of any liability to the Subscriber Indemnified Parties
under this Section 5.11(f), only to the extent that such failure materially
prejudices the Company’s ability to defend such action.  The failure to give
notice to the Company will not relieve it of any liability that it may have to
the Subscriber otherwise than under this Section 5.11(f).
(g)    To provide for just and equitable contribution to joint liability under
the Securities Act in any case in which contribution under the Securities Act
may be required on the part of the Subscriber Indemnified Parties, then such
parties will contribute to the aggregate losses, claims, damages, liabilities,
or expenses to which they may be subject (after contribution from others) in
such proportion as is appropriate to reflect the relative fault of the Company
and each Subscriber Indemnified Party in connection with the statements,
omissions, or other actions that resulted in such loss, claim, damage,
liability, or expense, as well as to reflect any other relevant equitable
considerations.  The relative fault of the Company and each Subscriber
Indemnified Party shall be determined by reference to, among other things,
whether the untrue or allegedly untrue statement of a material fact, or the
omission or alleged omission of a material fact, relates to information supplied
by the Company or by a Subscriber Indemnified Party and the parties’ relative
intent, knowledge, access to information, and opportunity to correct or prevent
such statement or omission; provided, however, that, in any such case (x) the
Subscriber will not be required to contribute any amount in excess of the public
offering price of all such Registrable Shares offered and sold by the Subscriber
pursuant to such registration statement, and (y) no Person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
will be entitled to contribution from any Person who was not guilty of such
fraudulent misrepresentation.
5.12    Nasdaq Matters. Prior to the Closing, the Company shall (a) take all
actions which are necessary, including providing appropriate notice to Nasdaq of
the transactions contemplated by this Agreement, for the Shares purchased at the
Closing to remain listed on the Nasdaq Global Select Market and (b) comply with
all listing, reporting, filing, and other obligations under the rules of Nasdaq
and of the SEC.
5.13    PFIC Reporting. If the Company determines it or any of its controlled
Subsidiaries was a “passive foreign investment company” (as defined in Section

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1297(a) of the Code) (a “PFIC”) for any taxable year in which the Subscriber
holds Shares in the Company, the Company shall (a) notify the Subscriber of such
determination, and (b) if requested in writing by the Subscriber, provide to
Subscriber such information as the Subscriber, in consultation with the Company,
reasonably determines is required for the Subscriber to (i) complete its U.S.
Internal Revenue Service Form 8621 with respect to such entity and (ii) make an
election to treat such entity as a “qualified electing fund” under Section 1295
of the Code.
5.14.    Controlled Foreign Corporation. If the Company determines it was a
“controlled foreign corporation” within the meaning of Section 957 of the Code
(a “CFC”) for any taxable year in which the Subscriber holds Shares in the
Company, the Company shall (a) notify the Subscriber of such determination and,
(b) for any taxable year in which the Company is a CFC and the Subscriber is a
“United States shareholder” (as defined in Section 951(b) of the Code), provide
to the Subscriber such information as the Subscriber, in consultation with the
Company, reasonably determines is required for the Subscriber to timely comply
with its filing obligations under the Code, including, but not limited to, its
U.S. Internal Revenue Service Form 5471.
6.    Conditions to Closing.

6.1    Conditions to Subscriber’s Obligations at the Closing.  The Subscriber’s
obligation to subscribe for the Shares at the Closing is subject to the
satisfaction, at or prior to the Closing Date, of the following conditions
(unless waived in writing by the Subscriber):
(a)    Representations and Warranties.  The representations and warranties made
by the Company in Section 3 shall be true and correct in all material respects
as of the Signing Date and the Closing Date as if made on such date, except to
the extent any such representation and warranty is (i) already qualified by
materiality, in which case it shall be true and correct as of such dates or
(ii) specifically made as of a particular date, in which case it shall be true
and correct in all material respects as of such date.
(b)    Performance of Obligations.  The Company shall have performed and
complied in all material respects with all agreements and conditions herein
required to be performed or complied with by the Company on or before the
Closing Date.
(c)    Legal Investment.  The issuance of the Shares shall be legally permitted
by all Laws to which the Subscriber and the Company are subject.
(d)    No Orders.  No Order shall be in effect preventing the consummation of
the transactions contemplated by the Transaction Agreements.
(e)    Closing Deliverables.  The Company shall deliver or cause to be delivered
to the Subscriber all items listed in Section 2.3(a).

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(f)    Collaboration Agreement.  The Company shall have executed the
Collaboration Agreement, the Effective Date (as such term is defined in the
Collaboration Agreement) of the Collaboration Agreement shall occur immediately
prior to the Closing, no material breach by the Company of any term of or
obligation under the Collaboration Agreement shall have occurred and be
continuing, and the Collaboration Agreement shall not have been terminated in
accordance with its terms.
(g)    Consents, Permits and Waivers.  All Consents necessary or appropriate for
consummation of the transactions contemplated by the Transaction Agreements
shall have been obtained, including the approval of the board of directors of
the Company. 
(h)    Material Adverse Effect.  No Material Adverse Effect shall have occurred
and be continuing.
(i)    The Company’s Nasdaq Listing.  The Company’s Ordinary Shares shall
continue to be listed on the Nasdaq Global Select Market.
6.2    Conditions to Company’s Obligations at the Closing.  The Company’s
obligation to issue and sell Shares at the Closing is subject to the
satisfaction, on or prior to the Closing Date, of the following conditions
(unless waived in writing by the Company):
(a)    Representations and Warranties.  The representations and warranties in
Section 4 made by the Subscriber shall be true and correct in all material
respects as of the Signing Date and the Closing Date as if made on such date,
except to the extent any such representation and warranty is (i) already
qualified by materiality, in which case it shall be true and correct as of such
dates or (ii) specifically made as of a particular date, in which case it shall
be true and correct in all material respects as of such date.
(b)    Performance of Obligations.  The Subscriber shall have performed and
complied with all agreements and conditions herein required to be performed or
complied with by the Subscriber on or before the Closing Date.
(c)    Legal Investment.  The issuance of the Shares shall be legally permitted
by all Laws to which the Subscriber and the Company are subject.
(d)    No Orders.  No Order shall be in effect preventing the consummation of
the transactions contemplated by the Transaction Agreements.
(e)    Closing Deliverables.  The Subscriber shall deliver or cause to be
delivered to the Company all items listed in Section 2.3(b).
(f)    Collaboration Agreement.  The Subscriber shall have executed the
Collaboration Agreement, the Effective Date (as such term is defined in the
Collaboration Agreement) of the Collaboration Agreement shall occur immediately
prior to the Closing, no material breach by the Subscriber of any term of or
obligation under the Collaboration

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Agreement shall have occurred and be continuing, and the Collaboration Agreement
shall not have been terminated in accordance with its terms.
(g)    Consents, Permits and Waivers.  All Consents necessary or appropriate for
consummation of the transactions contemplated by the Transaction Agreements
shall have been obtained. 
7.    Miscellaneous.
7.1    Termination. This Agreement may be terminated at any time prior to the
Closing by:
(a)    mutual written consent of the Company and the Subscriber;
(b)    either the Company or the Subscriber, upon written notice to the other no
earlier than ten Business Days following the Signing Date (the “Termination
Date”), if the Closing has not been consummated by the Termination Date;
(c)    either the Company or the Subscriber, upon written notice to the other,
if any of the conditions to the Closing set forth in Section 6.1(c), 6.1(d),
6.1(g), 6.2(c), 6.2(d) or 6.2(g) as applicable, despite the use of reasonable
efforts shall have become incapable of fulfillment by the Termination Date and
shall not have been waived in writing by the other party within ten Business
Days after receiving receipt of written notice of an intention to terminate
pursuant to this clause (c); provided, however, that the right to terminate this
Agreement under this Section 7.1(c) shall not be available to any party whose
failure to fulfill any obligation under this Agreement has been the cause of, or
resulted in, the failure to consummate the transactions contemplated hereby
prior to the Termination Date;
(d)    the Company, upon written notice to the Subscriber, so long as the
Company is not then in breach of its representations, warranties, covenants or
agreements under this Agreement such that any of the conditions set forth in
Section 6.1(a) despite the use of reasonable efforts could not be satisfied by
the Termination Date, (i) upon a material breach of any covenant or agreement on
the part of the Subscriber set forth in this Agreement, or (ii) if any
representation or warranty of the Subscriber shall have been or become untrue,
in each case such that any of the conditions set forth in Section 6.2(a) or
6.2(b), as applicable, could not be satisfied by the Termination Date (each (i)
and (ii), a “Terminating Subscriber Breach”); except that, if such Terminating
Subscriber Breach is curable by the Subscriber through the exercise of its
reasonable best efforts, then, for a period of up to thirty days after receipt
by the Subscriber of notice from the Company of such breach, but only as long as
the Subscriber continues to use its reasonable best efforts to cure such
Terminating Subscriber Breach (the “Subscriber Cure Period”), such termination
shall not be effective and the Termination Date shall be automatically extended
until the end of the Subscriber Cure Period, and such termination shall become
effective only if the Terminating Subscriber Breach is not cured within the
Subscriber Cure Period; or

33

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(e)    the Subscriber, upon written notice to the Company, so long as the
Subscriber is not then in breach of its representations, warranties, covenants
or agreements under this Agreement such that any of the conditions set forth in
Section 6.2(a) or 6.2(b), as applicable, despite the use of reasonable efforts
could not be satisfied by the Termination Date, (i) upon a material breach of
any covenant or agreement on the part of the Company set forth in this
Agreement, or (ii) if any representation or warranty of the Company shall have
been or become untrue, in each case such that any of the conditions set forth in
Section 6.1(a), 6.1(b), 6.1(h) or 6.1(i), as applicable, could not be satisfied
by the Termination Date (each (i) and (ii), a “Terminating Company Breach”);
except that, if such Terminating Company Breach is curable by the Company
through the exercise of its reasonable best efforts, then, for a period of up to
thirty days after receipt by the Company of notice from the Subscriber of such
breach, but only as long as the Company continues to use its reasonable best
efforts to cure such Terminating Company Breach (the “Company Cure Period”),
such termination shall not be effective and the Termination Date shall be
automatically extended until the end of the Company Cure Period, and such
termination shall become effective only if the Terminating Company Breach is not
cured within the Company Cure Period.
7.2    Effect of Termination. In the event of the termination of this Agreement
pursuant to Section 7.1, (a) this Agreement (except for this Section 7, and any
definitions set forth in this Agreement and used in such sections) shall
forthwith become void and have no effect, without any liability on the part of
any party hereto or its Affiliates, and (b) all filings, applications and other
submissions made pursuant to this Agreement, to the extent practicable, shall be
withdrawn from the agency or other Person to which they were made or
appropriately amended to reflect the termination of the transactions
contemplated hereby; provided, however, that nothing contained in this
Section 7.2 shall relieve any party from liability for fraud or any intentional
or willful breach of this Agreement; provided, however, that, a failure of a
Party to consummate the subscription for Shares in breach of this Agreement
shall be deemed to be intentional and willful.
7.3    Governing Law; Waiver of Jury Trial.  This Agreement shall be governed by
and construed in accordance with the Laws of the State of New York, without
regard to the conflict of laws principles thereof that would require the
application of the Law of any other jurisdiction. The parties irrevocably and
unconditionally submit to the exclusive jurisdiction of the United States
District Court for the Southern District of New York solely and specifically for
the purposes of any action or proceeding arising out of or in connection with
this Agreement. EACH OF THE PARTIES TO THIS AGREEMENT HEREBY AGREES THAT
JURISDICTION AND VENUE IN ANY SUIT, ACTION OR PROCEEDING BROUGHT BY ANY PARTY
ARISING OUT OF OR RELATING TO THIS AGREEMENT (INCLUDING ANY SUIT, ACTION OR
PROCEEDING SEEKING EQUITABLE RELIEF) SHALL PROPERLY AND EXCLUSIVELY LIE IN THE
STATE AND FEDERAL COURTS LOCATED IN THE STATE OF NEW YORK (THE “CHOSEN COURTS”).
EACH PARTY HERETO FURTHER AGREES NOT TO BRING ANY SUCH

34

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SUIT, ACTION OR PROCEEDING IN ANY COURT OTHER THAN THE CHOSEN COURTS PURSUANT TO
THE FOREGOING SENTENCE (OTHER THAN UPON APPEAL). BY EXECUTION AND DELIVERY OF
THIS AGREEMENT, EACH PARTY IRREVOCABLY SUBMITS TO THE JURISDICTION OF THE CHOSEN
COURTS FOR ITSELF AND IN RESPECT OF ITS PROPERTY WITH RESPECT TO SUCH SUIT,
ACTION OR PROCEEDING. THE PARTIES HERETO IRREVOCABLY AGREE THAT VENUE WOULD BE
PROPER IN EACH OF THE CHOSEN COURTS, AND HEREBY WAIVE ANY OBJECTION THAT ANY
SUCH CHOSEN COURT IS AN IMPROPER OR INCONVENIENT FORUM FOR THE RESOLUTION OF
SUCH SUIT, ACTION OR PROCEEDING. TO THE EXTENT NOT PROHIBITED BY APPLICABLE LAW
WHICH CANNOT BE WAIVED, EACH PARTY HERETO HEREBY WAIVES AND COVENANTS THAT IT
WILL NOT ASSERT (WHETHER AS PLAINTIFF, DEFENDANT OR OTHERWISE) ANY RIGHT TO
TRIAL BY JURY IN ANY FORUM IN RESPECT OF ANY ISSUE OR ACTION, CLAIM, CAUSE OF
ACTION OR SUIT (IN CONTRACT, TORT OR OTHERWISE) INQUIRY, PROCEEDING OR
INVESTIGATION ARISING OUT OF OR BASED UPON THIS AGREEMENT OR THE SUBJECT MATTER
HEREOF OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE TRANSACTIONS
CONTEMPLATED HEREBY, IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER ARISING.
EACH PARTY HERETO ACKNOWLEDGES THAT IT HAS BEEN INFORMED BY THE OTHER PARTIES
HERETO THAT THIS SECTION 7.3 CONSTITUTES A MATERIAL INDUCEMENT UPON WHICH THEY
ARE RELYING AND WILL RELY IN ENTERING INTO THIS AGREEMENT. ANY PARTY HERETO
MAY FILE AN ORIGINAL COUNTERPART OR A COPY OF THIS SECTION 7.3 WITH ANY COURT AS
WRITTEN EVIDENCE OF THE CONSENT OF EACH SUCH PARTY TO THE WAIVER OF ITS RIGHT TO
TRIAL BY JURY.
7.4    Survival.  The representations, warranties, covenants and agreements made
herein shall survive the Closing.
7.5    Successors and Assigns. The provisions hereof shall inure to the benefit
of, and be binding upon the parties hereto and their respective successors and
permitted assigns.  This Agreement, and any rights and obligations hereunder,
may not be assigned by any party hereto without the consent of the other party,
provided, however, that the Subscriber may assign its rights and obligations
hereunder in whole or in part to any Permitted Transferee or to any successor of
the Subscriber as a result of a Change of Control of the Subscriber, provided
further, that in the case of such permitted assignment, the assignee shall agree
in writing to be bound by the provisions of this Agreement and the Subscriber
shall not be relieved of its obligations hereunder.
7.6    Entire Agreement.  This Agreement, the exhibits and schedules hereto, the
other Transaction Agreement, and the other documents delivered pursuant hereto
constitute the full and entire understanding and agreement between the parties
with regard

35

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to the subjects hereof and no party shall be liable for or bound to any other in
any manner by any oral or written representations, warranties, covenants and
agreements except as specifically set forth herein and therein.
7.7    Severability.  In the event one or more of the provisions of this
Agreement should, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provisions of this Agreement, and this Agreement
shall be construed as if such invalid, illegal or unenforceable provision had
never been contained herein.  Upon such determination that any provision of this
Agreement, or the application of any such provision, is invalid, illegal, void
or unenforceable, the Company and the Subscriber shall negotiate in good faith
to modify this Agreement so as to effect the original intent of the Company and
the Subscriber as closely as possible to the fullest extent permitted by Law in
an acceptable manner to the end that the transactions contemplated hereby and
the other Transaction Agreement are fulfilled to the greatest extent possible.
7.8    Amendment.  No provision in this Agreement shall be supplemented, deleted
or amended except in a writing executed by an authorized representative of each
of the Subscriber and the Company.  Any amendment effected in accordance with
this Section 7.8 shall be binding upon each holder of Shares subscribed for
under this Agreement at the time outstanding, each future holder of all such
Shares, and the Company, and any amendment not effected in accordance with this
Section 7.8 shall be void and of no effect.
7.9    Waivers; Delays or Omissions.  It is agreed that no delay or omission to
exercise any right, power or remedy accruing to any party, upon any breach,
default or noncompliance by another party under this Agreement, shall impair any
such right, power or remedy, nor shall it be construed to be a waiver of any
such breach, default or noncompliance, or any acquiescence therein, or of or in
any similar breach, default or noncompliance thereafter occurring.  It is
further agreed that any Consent of any kind or character on any party’s part of
any breach, default or noncompliance under this Agreement or any waiver on such
party’s part of any provisions or conditions of the Agreement must be in writing
and shall be effective only to the extent specifically set forth in such
writing.  All remedies, either under this Agreement, by Law, or otherwise
afforded to any party, shall be cumulative and not alternative.  Any waiver
effected in accordance with this Section 7.9 shall be binding upon each holder
of Shares subscribed for under this Agreement at the time outstanding, each
future holder of all such Shares, and the Company, and any waiver not effected
in accordance with this Section 7.9 shall be void and of no effect.
7.10    Specific Performance.  Each of the Company and the Subscriber hereby
acknowledges and agrees that the failure of the Company or the Subscriber to
perform their respective agreements and covenants hereunder will cause
irreparable injury to the Subscriber or the Company, for which damages, even if
available, will not be an adequate

36

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remedy. Accordingly, each of the Company and the Subscriber hereby agrees that
the Subscriber and the Company shall be entitled to seek the issuance of
specific performance equitable relief by any court of competent jurisdiction to
compel performance of the Company’s or the Subscriber’s obligations.
7.11    Notices. Any and all notices or other communications or deliveries
required or permitted to be provided hereunder shall be in writing and shall be
deemed given and effective on the earliest of (a) the Business Day following the
date of mailing, if sent by U.S. nationally recognized overnight courier service
with next day delivery specified, (b) upon confirmation via electronic return
receipt if such notice or communication is delivered via email at an email
address specified in this Section 7.11 or (c) upon actual receipt by the party
to whom such notice is required to be given. The address for such notices and
communications shall be as follows:
If to the Company:
Prothena Corporation plc
Upper George’s Street
Dún Laoghaire
Co. Dublin, A96 T927, Ireland
Attention:     Company Secretary
E-mail:     yvonne.tchrakian@prothena.com

with copies to (which will not constitute notice) to:
Prothena Corporation plc
c/o Prothena Bioscience Inc
331 Oyster Point Boulevard
South San Francisco, CA 94080, U.S.A.
Attention:         Chief Financial Officer
E-mail:        tran.nguyen@prothena.com

Latham & Watkins LLP
140 Scott Drive
Menlo Park, CA 94025, U.S.A.
Attention:     Alan C. Mendelson, Esq.
Kathleen M. Wells, Esq.
E-mail:    alan.mendelson@lw.com
Kathleen.wells@lw.com

If to the Subscriber:
Celgene Switzerland LLC
86 Morris Avenue
Summit, NJ 07901, U.S.A.

37

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Attention:         Gerald F. Masoudi
E-mail:        gmasoudi@celgene.com

with a copy (which will not constitute notice) to:
Morgan, Lewis & Bockius LLP
502 Carnegie Center
Princeton, NJ 08540, U.S.A.
Attention:     Alan Leeds, Esq.
Emilio Ragosa, Esq.
E-mail:    Alan.Leeds@morganlewis.com
Emilio.Ragosa@morganlewis.com

7.12    Expenses.  Unless otherwise specified herein, each party shall pay all
costs and expenses that it incurs with respect to the negotiation, execution,
delivery and performance of this Agreement.
7.13    Titles and Subtitles.  The titles of the sections and subsections of the
Agreement are for convenience of reference only and are not to be considered in
construing this Agreement.
7.14    Pronouns.  All pronouns contained herein, and any variations thereof,
shall be deemed to refer to the masculine, feminine or neutral, singular or
plural, as to the identity of the parties hereto may require.  The words
“include,” “includes” and “including” will be deemed to be followed by the
phrase “without limitation”. The meanings given to terms defined herein will be
equally applicable to both the singular and plural forms of such terms. All
references to “dollars” or “$” will be deemed references to the lawful money of
the United States of America.  All exhibits attached hereto and all other
attachments hereto are hereby incorporated herein by reference and made a part
hereof.
7.15    Third Party Beneficiaries.  None of the provisions of this Agreement
shall be for the benefit of or enforceable by any Third Party, including any
creditor of any party hereto.  No Third Party shall obtain any right under any
provision of this Agreement or shall by reason of any such provision make any
claim in respect of any debt, liability or obligation (or otherwise) against any
party hereto.
7.16    No Strict Construction.  This Agreement has been prepared jointly and
will not be construed against either party.  In the event an ambiguity or
question of intent or interpretation arises, this Agreement shall be construed
as if drafted jointly by the parties hereto, and no presumption or burden of
proof shall arise favoring or disfavoring any party hereto by virtue of the
authorship of any provisions of this Agreement.
7.17    Execution. This Agreement may be executed in two or more counterparts,
all of which when taken together shall be considered one and the same

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agreement and shall become effective when counterparts have been signed by each
party and delivered to the other party, it being understood that both parties
need not sign the same counterpart. In the event that any signature is delivered
by facsimile transmission, or by e-mail delivery of a “.pdf” data file, such
signature shall create a valid and binding obligation of the party executing (or
on whose behalf such signature is executed) with the same force and effect as if
such facsimile signature page were an original thereof.
[Signature Page to Follow]
 

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IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the
date set forth in the first paragraph hereof.

Company:
Prothena Corporation plc

By: /s/ Yvonne Tchrakian    
Name: Yvonne Tchrakian
Title:     Company Secretary

[Signature Page to the Prothena Share Subscription Agreement]

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IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the
date set forth in the first paragraph hereof.

Subscriber:
Celgene Switzerland LLC

By: /s/     Kevin Mello    
Name:     Kevin Mello
Title:     Manager
 

[Signature Page to the Prothena Share Subscription Agreement]

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EXHIBIT A
COMPANY PRESS RELEASE

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prothenassaexecutionv_image1.jpg [prothenassaexecutionv_image1.jpg]

Prothena Announces Global Neuroscience Research & Development Collaboration with
Celgene for Novel Therapies for Patients with Neurodegenerative Diseases

•
Prothena to receive a $100 million upfront payment and a $50 million equity
investment by Celgene, with potential license payments and regulatory and
commercial milestones, plus additional royalties on net sales from licensed
programs

•
Collaboration focuses on preclinical programs targeting proteins implicated in
several neurodegenerative diseases, including tau, TDP-43 and an undisclosed
third target

•
Prothena to host an investor conference call and webcast today at 5:00 PM ET 

DUBLIN, Ireland – March 20, 2018 – Prothena Corporation plc (NASDAQ:PRTA), a
late-stage clinical biotechnology company focused on the discovery, development
and commercialization of novel therapies in the neuroscience and orphan
categories, today announced a global collaboration with Celgene Corporation
(NASDAQ:CELG) through a subsidiary, to develop new therapies for a broad range
of neurodegenerative diseases. The multi-year research and development
collaboration is focused on three proteins implicated in the pathogenesis of
several neurodegenerative diseases, including tau, TDP-43 and an undisclosed
target. For each of the programs, Celgene has an exclusive right to license
clinical candidates in the U.S. at the investigational new drug (IND) filing and
if exercised, would also have a right to expand the license to global rights at
the completion of Phase 1. Following the exercise of global rights, Celgene will
be responsible for funding all further global clinical development and
commercialization. Under the terms of the collaboration, Prothena will receive a
$100 million upfront payment and a $50 million equity investment by Celgene,
plus future potential exercise payments and regulatory and commercial milestones
for each licensed program. Prothena will also receive additional royalties on
net sales of any resulting marketed products.
 
“Prothena has a legacy of innovation in neuroscience and a team with a deep
understanding of biological approaches that target protein misfolding disorders.
Our collaboration leverages each company’s core expertise in protein homeostasis
and protein clearance to target proteins that are the underlying cause of many
neurodegenerative and orphan diseases. The programs we have chosen to
collaborate on have the potential to provide foundational assets from which we
can build new therapeutic approaches to these currently untreatable neurological
disorders” said Richard Hargreaves, PhD, Corporate Vice President Neuroscience
and Imaging for Celgene.

“We are excited to be working with Celgene, a leading global biopharmaceutical
company with deep expertise in targeting critical biological pathways involved
in protein homeostasis and an extensive track record of successfully bringing
forward innovative new therapies based on this

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biology,” said Gene Kinney, PhD, President and Chief Executive Officer of
Prothena. “As we build our pipeline of novel therapies across the neuroscience
and orphan disease categories, this collaboration provides Prothena the
opportunity to work with a premier scientific partner and the resources and
flexibility to advance these programs while continuing to expand our proprietary
discovery activities and further supports our efforts to deliver a diversified
pipeline of therapies to alter the course of devastating diseases.”

Collaboration Agreement Overview

Prothena will receive an upfront payment and equity investment, and is eligible
to receive exercise payments and regulatory and commercial milestones, plus
additional royalties on net sales based on the following collaboration deal
terms:

•
Prothena will receive an upfront payment of $100 million

•
Celgene will make a $50 million equity investment in Prothena by subscribing to
approximately 1.2 million of Prothena’s ordinary shares at $42.57 per share

•
For programs reaching commercialization, Prothena will receive tiered royalties
on net sales

The targets encompassed in this collaboration are implicated in the pathogenesis
of several neurodegenerative diseases for which there are no current disease
modifying therapies, including the following:

•
Tau, a protein implicated in diseases including Alzheimer's disease (AD),
progressive supranuclear palsy (PSP), frontotemporal dementia (FTD), chronic
traumatic encephalopathy (CTE) and other tauopathies. Prothena has identified
antibodies targeting novel epitopes on the tau protein with the ability to block
misfolded tau from binding to cells and to inhibit cell-to-cell transmission,
preventing downstream functional toxic effects.

•
TDP-43, a protein implicated in diseases including amytrophic lateral sclerosis
(ALS) and the most common subtype of FTD, behavioral variant FTD (bvFTD), a
proportion of AD and other TDP-43 proteinopathies. Prothena has generated
antibodies that target multiple epitopes on the TDP-43 protein and is using
proprietary in vitro screening methodology to select those that may be the most
potent and efficacious in inhibiting toxicity and cell-to-cell transmission of
misfolded TDP-43 species.

Citi is acting as financial advisor to Prothena and Latham & Watkins LLP is
acting as legal counsel to Prothena. Morgan Lewis is acting as legal counsel to
Celgene.

Investor Conference Call and Webcast Details

Prothena management will host a conference call and webcast to discuss the
collaboration today, March 20, at 5:00 PM ET. The conference call and webcast
will be made available on the Company's website at www.prothena.com under the
Investors tab in the Events and Presentations

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section. Following the conference call and webcast, a replay will be available
on the Company's website for at least 90 days.

To access the conference call via dial-in, please dial (877) 887-5215
(U.S./Canada toll free) or (315) 625-3069 (international) five minutes prior to
the start time and refer to conference ID number 8469456. A replay of the call
will be available until March 27 via dial-in at (855) 859-2056 (U.S./Canada toll
free) or (404) 537-3406 (international), Conference ID Number 8469456.

About Prothena
Prothena Corporation plc is a global, late-stage clinical biotechnology company
establishing fully integrated research, development and commercial capabilities
and focused on advancing new therapies in the neuroscience and orphan
categories. Fueled by its deep scientific understanding built over decades of
research in protein misfolding, Prothena seeks to fundamentally change the
course of grave or currently untreatable diseases associated with this biology.
Prothena’s pipeline of antibody therapeutic candidates targets a number of
indications including AL amyloidosis (NEOD001), Parkinson’s disease and other
related synucleinopathies (PRX002/RG7935) and ATTR amyloidosis (PRX004). The
Company continues discovery of additional novel therapeutic approaches against
targets such as tau, Aβ (Amyloid beta) and ALECT2 where its deep scientific
understanding of disease pathology can be leveraged. For more information,
please visit the Company's website at www.prothena.com.
Forward-looking Statements by Prothena

This press release contains forward-looking statements by Prothena. These
statements relate to, among other things, potential future payments and
royalties we might receive under the collaboration with Celgene; our ability to
advance a growing pipeline of novel therapies in the neuroscience and orphan
disease categories; our ability to advance any of the programs that are the
subject of the collaboration with Celgene; the potential of those programs to
lead to new therapeutic approaches to currently untreatable neurological
disorders; the potential targeting of novel epitopes on misfolded forms of tau
protein and LECT2 protein; and the capabilities of our proprietary in vitro
screening methodology for TDP-43. These statements are based on estimates,
projections and assumptions that may prove not to be accurate, and actual
results could differ materially from those anticipated due to known and unknown
risks, uncertainties and other factors, including but not limited to the risks,
uncertainties and other factors described in the “Risk Factors” sections of
Prothena’s Annual Report on Form 10-K filed with the Securities and Exchange
Commission (SEC) on February 26, 2018 and Prothena’s subsequent Quarterly
Reports on Form 10-Q filed with the SEC. Prothena undertakes no obligation to
update publicly any forward-looking statements contained in this press release
as a result of new information, future events or changes in Prothena’s
expectations.

Contact:

Ellen Rose, Head of Communications
650-922-2405
ellen.rose@prothena.com