Document:

Facility Agreement, dated June 17, 2009

 Exhibit 10.1 
 EXECUTION VERSION 
 FACILITY AGREEMENT 
 FACILITY AGREEMENT (this “Agreement”), dated as of June 17, 2009, between Arena Pharmaceuticals, Inc., a Delaware corporation (the
“Borrower”) and the parties identified on Schedule 1 hereto (each individually, a “Lender” and together, the “Lenders” and, together with the Borrower, the “Parties”).

 W I T N E S S E T H 
 WHEREAS, the Borrower wishes to borrow from the Lenders, and the Lenders wish to lend to the Borrower, one hundred million Dollars ($100,000,000) for the purpose described in Section 2.1; and 
 WHEREAS, the Lenders desire to have a right to make an additional loan up to twenty million Dollars ($20,000,000) to the Borrower for such purpose;

 NOW, THEREFORE, in consideration of the mutual agreements set forth herein, the Lenders and the Borrower agree as follows: 
 ARTICLE I 
 DEFINITIONS

 Section 1.1 General Definitions. Wherever used in this Agreement, the Exhibits or the Schedules attached hereto,
unless the context otherwise requires, the following terms have the following meanings: 
 “Affiliate” means, with respect
to any Person, any other Person that, directly or indirectly through one or more intermediaries, controls or is controlled by or is under common control with such first Person, as such terms are used in and construed under Rule 144 under the
Securities Act. Without limiting the generality of the foregoing, with respect to a Lender or holder of Warrants, any investment fund or managed account that is managed on a discretionary basis by the same investment manager as such holder or Lender
will be deemed to be an Affiliate of such holder or Lender. 
 “Business Day” means a day on which banks are open for
business in The City of New York and San Diego, California. 
 “Call Loan” means up to twenty million Dollars ($20,000,000)
in an additional loan made by the Lenders to the Borrower upon the Note Call. 
 “Call Notes” means notes issued to the
Lenders upon exercise of the Note Call to evidence the Call Loan in the forms of Exhibits A-1, A-2, A-3, A-4, A-5 and A-6. 
 “Code” means the Internal Revenue Code of 1986, as amended, and any Treasury Regulations promulgated thereunder. 
 “Collateral” has the meaning given to it in the Security Agreement. 
  

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 “Common Stock” means the common stock, par value $0.0001 per share, of the Borrower.

 “Convertible Securities” means any stock or securities directly or indirectly convertible into or exercisable or
exchangeable for Common Stock. 
 “Default” means any event which, at the giving of notice, lapse of time or fulfillment of
any other applicable condition (or any combination of the foregoing), would constitute an Event of Default. 
 “Disbursement” has the meaning given to it in Section 2.2. 
 “Disbursement Date” has the
meaning given to it in Section 2.2. 
 “Dollars” and the “$” sign mean the lawful currency of the
United States of America. 
 “Event of Default” has the meaning given to it in Section 5.5. 
 “Evidence of Disbursement” has the meaning given to it in Section 2.2. 
 “Exchange Act” means the Securities Exchange Act of 1934, as amended, including the rules and regulations promulgated thereunder.

 “Excluded Taxes” means all income taxes, minimum or alternative minimum income taxes, withholding taxes imposed on gross
amounts, any tax determined based upon income, capital gains, gross income, sales, net profits, windfall profits or similar items, franchise taxes (or any other tax measured by capital, capital stock or net worth), gross receipts taxes, branch
profits taxes, margin taxes (or any other taxes imposed on or measured by net income, or imposed in lieu of net income) payable by the Lenders in any jurisdiction to any Government Authority (or political subdivision or taxing authority thereof) in
connection with any payments received under this Agreement by the Lenders, or any similar tax imposed in connection with the execution and delivery of, and the performance of its obligations under, this Agreement. 
 “Exempted Issuance” means any Common Stock, Convertible Securities, Options, equity incentive awards or other equity securities issued,
deemed to have been issued or issuable (a) upon the conversion, exchange, vesting, or exercise of any Option, Convertible Security, equity incentive award or other equity securities outstanding prior to the date of this Agreement; (b) to
officers, directors, employees, consultants or advisors pursuant to any contract, plan or arrangement approved by a majority of the non-employee members of the Board of Directors of the Borrower or a majority of the members of a committee of
non-employee directors established for such purpose, including any Common Stock issued or deemed to have been issued upon the conversion, exchange, vesting or exercise of any such security; (c) pursuant to the Financing Documents; (d) as
consideration for mergers or consolidations or acquisitions of businesses or their tangible or intangible assets, excluding any such acquisition transactions in which cash or cash equivalents represent a majority of the assets acquired; (e) in
connection with any strategic partnership, joint venture, collaborative arrangement or licensing agreement; (f) in connection with a pro rata dividend or distribution of securities to the Borrower’s existing securityholders; or
(g) the Net Proceeds of which are applied within one (1) Business Day to repay all or a portion of the Loan. 
  

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 “Facility Documents” means this Agreement, the Notes, the Security Agreement and any
other document or instrument delivered in connection with any of the foregoing whether or not specifically mentioned herein or therein; provided that the Facility Documents shall not include the Registration Rights Agreement or the Warrants or any
other document or instrument delivered exclusively in connection with any of the foregoing. 
 “Final Payment” means such
amount as may be necessary to repay the Loan in full and any other amounts owing by the Borrower to the Lenders pursuant to this Agreement. 
 “Final Payment Date” means the earlier of (i) the date on which the Borrower makes the Final Payment and (ii) the fourth anniversary of the date of this Agreement. 
 “Financing Documents” means the Facility Documents, the Warrants, the Registration Rights Agreement and any other document or instrument
delivered in connection with any of the foregoing whether or not specifically mentioned herein or therein. 
 “Government
Authority” means any government, governmental department, ministry, cabinet, commission, board, bureau, agency, tribunal, regulatory authority, instrumentality, judicial, legislative, fiscal, or administrative body or entity, whether
domestic or foreign, federal, state or local, having jurisdiction over the matter or matters and Person or Persons in question, including, with limitation, the SEC. 
 “Indemnified Person” has the meaning given to it in Section 6.11. 
 “Indemnity” has the meaning given to it in Section 6.11. 
 “Interest Rate” means
7.75% per annum. 
 “Lien” means any lien, pledge, preferential arrangement, mortgage, security interest, deed of
trust, charge, assignment, hypothecation, title retention, privilege or other encumbrance on or with respect to property or interest in property having the practical effect of constituting a security interest, in each case with respect to the
payment of any obligation with, or from the proceeds of, any asset or revenue of any kind. 
 “Loan” means the loans to be
made available by the Lenders to the Borrower pursuant to Section 2.2 initially in the aggregate principal amount of one hundred million Dollars ($100,000,000) and, if the Lenders exercise the Note Call, the sum of such principal amount and the
principal amount of the Call Loan. 
 “Loss” has the meaning given to it in Section 6.11. 
 “Major Transaction” has the meaning set forth in the Warrants. 
  

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 “Major Transaction Put Date” means the date specified for payment in the Put Notice,
which date shall not be less than ten (10) Business Days nor more than twenty (20) Business Days after the date that the Put Notice is given. 
 “Material Adverse Effect” means a material adverse effect on (a) the business, operations or financial condition of the Borrower and its Subsidiaries taken as a whole, (b) the validity or
enforceability of any provision of any Financing Document, (c) the ability of the Borrower to timely perform the Obligations or (d) the rights and remedies of the Lenders under any Financing Document; provided, however, that none of the
following shall be deemed either alone or in combination to constitute, and none of the following shall be taken into account in determining whether there has been or would be, a Material Adverse Effect: (A) any adverse effect that results
directly or indirectly from general economic, business, financial or market conditions; and (B) any adverse effect arising directly or indirectly from or otherwise relating to any of the industries or industry sectors in which the Borrower
operates. 
 “Net Proceeds” means, with respect to any financing transaction, the gross proceeds received by the Borrower in
connection therewith, less any expenses related to the consummation of such financing (and the issuance of any securities in connection therewith), including underwriters’ discounts or other commissions, legal, financial or accounting advisory
service expenses and out-of-pocket expenses incurred in connection marketing and diligence efforts. 
 “Note Call” has the
meaning set forth in Section 2.14. 
 “Notes” means the notes issued to the Lenders on the date of this Agreement
evidencing the Loan in the forms attached hereto as Exhibits A-1, A-2, A-3, A-4, A-5 or A-6 and, if the Lenders exercise the Note Call, the Call Notes. 
 “Obligations” means all obligations (monetary or otherwise) of the Borrower arising under or in connection with the Facility Documents. 
 “Options” means any rights, warrants or options to subscribe for or purchase Common Stock or Convertible Securities. 
 “Organizational Documents” means the Amended and Restated Certificate of Incorporation, and the certificate of amendment thereto, and
the Amended and Restated By-laws of the Borrower, each as in effect from time to time. 
 “Permitted Indebtedness” means:
(a) indebtedness of Borrower in favor of the Lenders arising under this Agreement, (b) indebtedness existing as of the date hereof and set forth on Exhibit C to this Agreement, (c) indebtedness to trade creditors incurred in the
ordinary course of business, (d) indebtedness (and guaranties thereof) in respect of purchase money financing, capital lease obligations, equipment financing facilities and sale-leaseback financing transactions, (e) any indebtedness for
borrowed money so long as no principal of such indebtedness is scheduled to mature before the stated maturity of the Loan and such indebtedness is subject to the Specified Subordination Terms, (f) indebtedness in respect of any and all interest
rate swap transactions, basis swaps, credit derivative transactions, forward interest rate transactions, commodity swaps, commodity options, forward commodity contracts, equity or equity index swaps or options, bond or bond price or bond index swaps
or options or forward bond or forward bond price or 

  

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forward bond index transactions, interest rate options, forward foreign exchange transactions, interest rate or foreign exchange rate cap, floor or collar
transactions, currency swap transactions, cross-currency rate swap transactions, currency options, spot contracts, or any other similar transactions or any combination of any of the foregoing (including any options to enter into any of the
foregoing), (g) any indebtedness the Net Proceeds of which are used to prepay the Loan, (h) indebtedness incurred in connection with collaboration, licensing, joint venture or partnership arrangements, (i) indebtedness incurred to
finance insurance premiums or time-based license royalties or payments in the ordinary course of business, (j) indebtedness in respect of workers’ compensation claims, self-insurance obligations, indemnities, bankers’ acceptances,
performance and surety bonds, appeal or other similar bonds, in each case in the ordinary course of business, in any such case, any reimbursement obligations in connection therewith, (k) indebtedness in respect of netting services, overdraft
protections and other similar and customary services in connection with deposit accounts, (l) guaranties in the ordinary course of business of the obligations of suppliers, customers and licensees of the Borrower, (m) indebtedness owed to
any Subsidiary of the Borrower, (n) indebtedness in connection with letter of credit obligations incurred in the ordinary course of business, (o) indebtedness arising from agreements providing for indemnification, (p) unsecured
guaranties of indebtedness of Subsidiaries, and (q) extensions, refinancings, replacements and renewals of any item of Permitted Indebtedness, provided that the principal amounts and premiums, if any, are not increased (plus the amount of any
customary penalties, premiums and costs and expenses incurred therewith, including any original issue discount). 
 “Permitted
Liens” means: (a) Liens existing on the date hereof and set forth on Exhibit D to this Agreement; (b) Liens in favor of the Lenders; (c) statutory Liens created by operation of applicable law; (d) Liens arising in the
ordinary course of business and securing obligations that are not overdue or are being contested in good faith by appropriate proceedings; (e) Liens securing purchase money or capitalized lease equipment financing; (f) Liens for Taxes not
yet due and payable or that are being contested in good faith by appropriate proceedings; (g) pledges or deposits in the ordinary course of business in connection with workers’ compensation, unemployment insurance and other social security
legislation; (h) deposits to secure the performance of bids, trade contracts and leases, regulatory or statutory obligations, surety and appeal bonds, performance bonds and other obligations of a like nature incurred in the ordinary course of
business; (i) easements, rights-of-way, municipal and zoning and building ordinances, title defects or other irregularities, restrictions and other similar encumbrances affecting real property which do not in any case materially detract from
the value of the property subject thereto or materially interfere with the ordinary conduct of the business of the applicable Person; (j) Liens securing judgments for the payment of money not constituting an Event of Default; (k) Liens
securing Permitted Indebtedness; (l) Liens on a property of, or on shares of stock of, a Person existing at the time such Person is merged into or consolidated with the Borrower or a Subsidiary and Liens on property existing at the time of
acquisition thereof by the Borrower or any Subsidiary; provided that such Liens were not placed on such property in contemplation of the consummation of such merger, consolidation or acquisition and do not extend to any assets other than those of
the Person merged into or consolidated with the Borrower or any such Subsidiary, or the property so acquired, and proceeds and products of any of the foregoing; (m) Liens arising from filing Uniform Commercial Code financing statements (or
substantially equivalent filings outside the United States) regarding leases (other than indebtedness); (n) leases, licenses, subleases or sublicenses granted to others that do not materially interfere with 

  

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the business of the Borrower and the Subsidiaries, taken as a whole, including without limitation any lease, license, sublease or sublicense not prohibited
by Article V and with respect to any license or sublicense where Borrower is the licensee or sublicensee, any interest or title of a licensor or sublicensor under any such license or sublicense; (o) any option or other agreement to purchase any
asset of the Borrower or any Subsidiary the disposition of which is not otherwise prohibited hereby; (p) the disposition of accounts receivables in connection with collection in the ordinary course of business; (q) Liens in favor of
financial institutions arising in connection with Borrower’s accounts maintained in the ordinary course of Borrower’s business held at such institutions to secure standard fees for services charged by, but not financing made available by,
such institutions; (r) Liens occurring solely by filing of a Uniform Commercial Code financing statement (or substantially equivalent filings outside the United States) which filing has not been consented to by Borrower; (s) cash
collateral pledged to secure standby letter of credit obligations; and (t) Liens securing reimbursement obligations with respect to commercial letters of credit which encumber documents and other property relating to such letters of credit and
products and proceeds thereof. 
 “Person” means and includes any natural person, individual, partnership, joint venture,
corporation, trust, limited liability company, limited company, joint stock company, unincorporated organization, government entity or any political subdivision or agency thereof, or any other entity. 
 “Prepayment Financing” means any sale by the Borrower of any Common Stock, Convertible Securities or Options, other than any Exempted
Issuance. 
 “Put Notice” has the meaning given to it in Section 5.4. 
 “Put Price” has the meaning given to it in Section 5.4. 
 “Qualified Major Transaction” has the meaning set forth in the Warrants. 
 “Registration Rights Agreement” means the Registration Rights Agreement, dated as of the date hereof, between the Borrower and the
Lenders. 
 “Requisite Lenders” means at any time the Lenders then holding Notes representing more than 50% of the aggregate
unpaid principal amount of the Loan then outstanding. 
 “SEC” means the United States Securities and Exchange Commission.

 “Securities Act” means the Securities Act of 1933, as amended, including the rules and regulations promulgated
thereunder. 
 “Security Agreement” means the Security Agreement, dated as of the date hereof, between the Borrower and the
Lenders. 
 “Specified Subordination Terms” means that no payment in respect of the indebtedness described in clause
(e) of the definition of Permitted Indebtedness may be made if (a) an Event of Default pursuant to Section 5.5(a) shall have occurred and is continuing, unless and until such Event of Default is waived or the Loan has been paid in
full; (b) any Event of Default has occurred and an 

  

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Acceleration Notice (as defined in Section 5.5) has been delivered, unless and until such Acceleration Notice is rescinded or the Loan has been paid in
full, or (c) any other Event of Default shall have occurred and be continuing and the Lenders shall have sent to the Borrower a notice of default (a “Payment Blockage Notice”); provided that no more than one Payment Blockage
Notice may be sent during any three hundred sixty-five (365) day period and payments in respect of such indebtedness may resume upon the earliest to occur of (i) the date on which such default is cured or waived, (ii) the date
ninety-one (91) days after the date the Final Payment Date, (iii) the date one hundred seventy-nine (179) days after the date on which the Payment Blockage Notice is received, and (iv) the date the Payment Blockage Notice is
rescinded; provided further, that the sending of a Payment Blockage Notice shall not preclude Lenders from delivering an Acceleration Notice in respect of such Event of Default at any time before or after a Payment Blockage Notice is sent in
which event clause (b) of this definition shall control with respect to the Acceleration Notice and in the event the Acceleration Notice is rescinded, clause (c) hereof will control as to any time still remaining with respect to the
Payment Blockage Notice.. 
 “Subsidiary” or “Subsidiaries” means, as to the Borrower, any entity of which
securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at the time directly or indirectly owned by the Borrower. 
 “Taxes” means all deductions or withholdings for any and all present and future taxes, levies, imposts, stamp or other duties, fees,
assessments, deductions, withholdings, all other similar governmental charges, and all liabilities with respect thereto. 
 “Warrants” means the warrants in the form attached hereto as Exhibit B and issued pursuant to Section 2.12. 
 Section 1.2 Interpretation. In this Agreement, unless the context otherwise requires, all words and personal pronouns relating thereto shall be read and construed as the number and gender of the party or parties requires
and the verb shall be read and construed as agreeing with the required word and pronoun; the division of this Agreement into Articles and Sections and the use of headings and captions is for convenience of reference only and shall not modify or
affect the interpretation or construction of this Agreement or any of its provisions; the words “herein,” “hereof,” “hereunder,” “hereinafter” and “hereto” and words of similar import refer to this
Agreement as a whole and not to any particular Article or Section hereof; the words “include,” “including,” and derivations thereof shall be deemed to have the phrase “without limitation” attached thereto unless
otherwise expressly stated; references to a specified Article, Exhibit, Section or Schedule shall be construed as a reference to that specified Article, Exhibit, Section or Schedule of this Agreement; and any reference to any of the Financing
Documents means such agreement or document as the same shall be amended, supplemented or modified and from time to time in effect. 
 Section 1.3 Business Day Adjustment. If the day by which a payment is due to be made is not a Business Day, that payment shall be made by the next succeeding Business Day unless that next succeeding Business Day falls in
a different calendar month, in which case that payment shall be made by the Business Day immediately preceding the day by which such payment is due to be made. Any such extension or reduction of time will not be taken into account in the computation
of interest. 
  

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 ARTICLE II 
 AGREEMENT FOR THE LOAN 
 Section 2.1 Use of Proceeds. The Borrower shall use the
Loan for general corporate purposes. 
 Section 2.2 Disbursements. Subject to satisfaction of the conditions contained in Article
IV, the Lenders jointly and severally agree to disburse the initial Loan (the “Disbursement”) to the Borrower in the aggregate principal amount of one hundred million Dollars ($100,000,000) on the date that is fifteen
(15) Business Days from date of this Agreement, or such earlier date as is agreed to by the Company and the Lenders (the “Disbursement Date”). Against such Disbursement, the Borrower shall deliver to the Lenders a completed
receipt (the “Evidence of Disbursement”) in the form of Schedule 2, which receipt shall not be effective until the Disbursement is actually advanced to the Borrower. The Loan and the Disbursement shall be evidenced by
the Evidence of Disbursement and one or more accounts or records maintained by the Lenders in the ordinary course of business. 
 Section 2.3 Repayment. The Borrower shall remit the Final Payment to the Lenders on the earlier to occur of (a) the Final Payment Date and (b) the Major Transaction Put Date. 
 Section 2.4 Transaction Fee. Within one (1) Business Day following the Disbursement Date, the Borrower shall pay to Deerfield
Management Company, L.P. a transaction fee of $2,250,000. 
 Section 2.5 Payments. Payments of any amounts due to the Lenders
under this Agreement shall be made in Dollars in immediately available funds prior to 1:00 p.m. New York City time on such date, subject to Section 1.3, that any such payment is due, at such bank or places, as the Lenders shall from time
to time designate in writing. The Borrower shall pay all and any costs (administrative or otherwise) imposed by banks, clearing houses, or any other financial institution, in connection with making any payments under any of the Facility Documents,
except for any costs imposed by any of the Lenders’ banking institutions. 
 Section 2.6 Taxes, Duties and Fees. 

(a) The Borrower shall pay or cause to be paid all present and future Taxes (other than Excluded Taxes, if any), if any, duties, fees,
and other charges of whatsoever nature, now or at any time hereafter levied or imposed by any Government Authority, by any department, agency, political subdivision or taxing or other authority thereof or therein, or by any organization of which the
applicable Government Authority is a member, or by any jurisdiction through which the Borrower makes payments hereunder, on or in connection with the payment of any on all amounts due under this Agreement, and all payments of principal and other
amounts due under this Agreement shall be made without deduction for or on account of any such Taxes, except for Excluded Taxes, which may be deducted or withheld from payments made by the Borrower only if such deduction or withholding is required
by applicable law. 
  

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 (b) If the Borrower is required to withhold any such amount or is prevented by operation
of law or otherwise from paying or causing to be paid such Taxes, except for Excluded Taxes, the principal or other amounts due under this Agreement (as applicable) shall be increased to such amount as shall be necessary to remit to the Lenders the
full amount they would have received taking into account any such Taxes (except for Excluded Taxes) on amounts payable by the Borrower under this Section 2.6(b) had such payment been made without deduction of such Taxes (all and any of such
additional amounts, herein referred to as the “Additional Amounts”). 
 (c) Notwithstanding anything to the
contrary herein, Additional Amounts shall not be payable to the extent the obligation to withhold or deduct would not have arisen but for the failure of a Lender or assignee to deliver a properly completed and duly executed form establishing an
exemption from or reduction in Tax required under applicable law as a condition to the exemption or reduction absent a change in applicable law (including treaties), which such Lender is eligible to provide. 
 (d) If Section 2.6(b) above applies and the Lenders so require, the Borrower shall deliver to the Lenders official tax receipts
evidencing payment or a copy of the filed Tax return reporting such payment (or certified copies thereof) of the Additional Amounts within thirty (30) days of the date of payment. 
 (e) If the Lenders receive a refund from a Government Authority to which the Borrower has paid withholding Taxes pursuant to this
Section 2.6, or relating to Taxes in respect of which the Borrower paid Additional Amounts, the Lenders shall promptly pay such refund to the Borrower. 
 Section 2.7 Costs, Expenses and Losses. If, as a result of any failure by the Borrower to pay any sums due under this Agreement on the due date therefor (after the expiration of any applicable grace
periods), the Lenders shall incur costs, expenses and/or losses, by reason of the liquidation or redeployment of deposits from third parties or in connection with obtaining funds to maintain the Disbursement, the Borrower shall pay to the Lenders
upon request by the Lenders, the amount of such costs, expenses and/or losses within fifteen (15) days after receipt by it of a certificate from the Lenders setting forth in reasonable detail such costs, expenses and/or losses, along with
supporting documentation. For the purposes of the preceding sentence, “costs, expenses and/or losses” shall include, without limitation, any interest paid or payable to carry any unpaid amount and any loss, premium, penalty or expense
which may be incurred in obtaining, liquidating or employing deposits of or borrowings from third parties in order to maintain or fund the Loan or any portion thereof. 
 Section 2.8 Interest Rate. The outstanding principal amount of the Loan shall bear interest at the Interest Rate (calculated on the basis of the actual number of days elapsed) and shall be paid in
arrears quarterly commencing on September 17, 2009 and, subject to Section 1.3, on the 17th day of each September, December, March and June thereafter. 
  

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 Section 2.9 Interest on Late Payments. Without limiting the remedies available to the
Lenders under the Financing Documents or otherwise, to the maximum extent permitted by applicable law, if the Borrower fails to make any payment of principal with respect to the Loan when due, the Borrower shall pay, in respect of the outstanding
principal amount and interest of the Loan, interest at the rate per annum equal to the Interest Rate plus five hundred (500) basis points for so long as such payment remains outstanding. Such interest shall be payable on demand. 
 Section 2.10 Optional Prepayment. The Borrower may prepay the Loan, at any time without premium or penalty. 
 Section 2.11 Prepayment Upon Exercise of Warrants. The Loan shall be deemed prepaid to the extent a Lender satisfies the payment of the
Exercise Price (as such term is defined in the Warrants) through a reduction of the principal amount outstanding under such Lender’s Notes in accordance with Section 3(a)(i) of the Warrants. 
 Section 2.12 Mandatory Prepayment. 
 (a) Notwithstanding Section 2.3, the Borrower shall prepay the Loan in cash in an amount equal to the lesser of (i) 35% of the Net Proceeds from each Prepayment Financing, and (ii) the then unpaid principal amount of the next
scheduled installment of principal set forth under Section 2.12(b); provided, however that the first $5 million of such Net Proceeds in each 12 month period commencing on the Disbursement Date shall not be required to be used to prepay the Loan
pursuant to the provisions of this Section 2.12(a). Any such prepayment shall be made within one (1) Business Day following the date such proceeds are received. 
 (b) Notwithstanding Section 2.3, the Borrower shall prepay the Loan (which for the purpose of this Section 2.12(b) shall not include the Call Loan) in cash on the first anniversary of the Disbursement Date
in the principal amount of ten million Dollars ($10,000,000), on the second anniversary of the Disbursement Date in the principal amount of twenty million Dollars ($20,000,000), and on the third anniversary of the Disbursement Date in the principal
amount of thirty million Dollars ($30,000,000). 
 (c) Notwithstanding Section 2.3, the Borrower shall prepay the Loan in cash in full
within five days of the issuance by the Borrower of Common Stock, other than an Exempted Issuance, at a price of less than $2.00 (the “Minimum Price”). If the Borrower shall at any time effect a stock split, payment of stock
dividend, recapitalization, reclassification or other similar transaction of such character that the shares of Common Stock shall be changed into or become exchangeable for a larger number of shares, then upon the effective date thereof, the Minimum
Price shall be proportionately decreased. 
 (d) Notwithstanding Section 2.12(b), any principal prepaid on the Loan, including pursuant
to Sections 2.10, 2.11 and this Section 2.12, shall be applied to reduce the scheduled installments of principal set forth in Section 2.12(b) in forward chronological order. 
  

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 Section 2.13 Application of Payments. The proceeds of any prepayment shall be applied first
to accrued and unpaid interest on the Loan and second to the outstanding principal amount of the Loan. Any prepayment shall be applied pro rata to the outstanding Notes. 
 Section 2.14 Note Call. On or before the second anniversary of the date of this Agreement, the Lenders, in their sole discretion, may elect
to make the Call Loan (the “Note Call”) upon five (5) days’ prior written notice to the Borrower (indicating the disbursement date and the principal amount thereof); provided that the Call Loan shall be in a principal
amount of at least one million Dollars ($1,000,000) and in whole increments of one million Dollars ($1,000,000) in excess thereof. The Lenders may only exercise the Note Call once. On the disbursement date of the Call Loan, the Borrower shall issue
to the Lenders the Call Notes. 
 Section 2.15 Delivery of Warrants. 
 (a) On the Disbursement Date, the Borrower shall issue to the Lenders Warrants in the form attached hereto as Exhibit B to purchase an
aggregate of 28,000,000 shares of Common Stock at an initial Exercise Price (as defined in the Warrants) of $5.42 (the “Initial Exercise Price”). 
 (b) Concurrently with the disbursement of the Call Loan, the Borrower shall issue to Lenders Warrants to purchase two hundred and eighty thousand (280,000) shares of Common Stock for each $1,000,000 in principal
amount of the Call Loan. The Warrants issued in respect of any Note Call shall be in the form attached hereto as Exhibit B containing an initial Exercise Price equal to the Initial Exercise Price. Notwithstanding the foregoing, the Initial Exercise
Price and/or the number of shares underlying any such Warrants shall be adjusted to reflect any adjustments in the number of shares of Common Stock into which such Warrant is exercisable that would have taken effect pursuant to the terms of the
Warrant had such Warrant been issued on the date hereof and remained outstanding through the date of such issuance. 
 (c) All
Warrants issued pursuant to this Section 2.15 shall be allocated among the Lenders as set forth on Schedule 1. 
 ARTICLE III

 REPRESENTATIONS AND WARRANTIES 
 Section 3.1 Representations and Warranties of the Borrower. The Borrower represents and warrants as of the date hereof as follows: 
 (a) The Borrower is a corporation duly organized and validly existing under the laws of the State of Delaware. 
 (b) The Borrower is conducting its business in compliance with its Organizational Documents. The Organizational Documents of the Borrower
(including all amendments thereto) as currently in effect have been made available to the Lenders and remain in full force and effect with no defaults outstanding thereunder. 
  

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 (c) The Borrower has full power and authority to enter into each of the Financing
Documents and to make the borrowings and the other transactions contemplated thereby. 
 (d) All authorizations, consents,
approvals, registrations, exemptions and licenses that are necessary for the borrowing hereunder, the execution and delivery of the Financing Documents and the performance by the Borrower of its obligations thereunder, have been obtained and are in
full force and effect, except for registrations and filings in connection with the issuance of the Warrants and shares of Common Stock pursuant the Financing Documents, filings, recordings or registrations contemplated by the Security Agreement and
filings necessary to comply with laws, rules, regulations and orders required in the ordinary course of business. 
 (e) All
authorizations, consents, approvals, registrations, exemptions and licenses with or from Government Authorities that are necessary for the conduct of its business as currently conducted have been obtained and are in full force and effect, except to
the extent any failure to so obtain would not reasonably be expected to have a Material Adverse Effect. 
 (f) No Default or
Event of Default (or any other default or event of default, however described) has occurred under any of the Financing Documents. 
 (g) Neither the entering into any of the Financing Documents nor the compliance with any of its terms conflicts with, violates or results in a breach of any of the terms of, or constitutes a default or event of default (however described)
or requires any consent under, to the extent applicable, (i) any agreement to which the Borrower is a party or by which it is bound, (ii) any of the terms of the Organizational Documents or (iii) any judgment, decree, resolution,
award or order or any statute, rule or regulation applicable to the Borrower or its assets, except where such conflicts, violations, breaches or defaults, individually or in the aggregate, would not reasonably be expected to have a Material Adverse
Effect. 
 (h) The Borrower is not engaged in or the subject of any litigation, arbitration, administrative regulatory
compliance proceeding, or investigation, nor are there any litigation, arbitration, administrative, regulatory, compliance proceedings or investigations pending or, to the knowledge of the Borrower, threatened before any court or arbitrator or
before or by any Government Authority against the Borrower, that would reasonably be expected to result in a Material Adverse Effect and the Borrower is not aware of any facts reasonably likely to give rise to any such proceeding. 
 (i) The Borrower (i) is capable of paying its debts as they fall due and is not unable and has not admitted its inability to pay
debts as they fall due, (ii) is not bankrupt or insolvent and (iii) has not taken action, and no such action has been taken by a third party, for the Borrower’s winding up, dissolution, or liquidation or similar executory or judicial
proceeding or for the appointment of a liquidator, custodian, receiver, trustee, administrator or other similar officer for the Borrower or any or all of its assets or revenues. 
  

 12 

 (j) No Lien exists on Borrower’s property, except for Permitted Liens. 

(k) The obligation of the Borrower to make any payment under this Agreement (together with all charges in connection therewith) is
absolute and unconditional, and there exists no right of setoff or recoupment, counterclaim, cross-claim or defense of any nature whatsoever to any such payment. 
 Section 3.2 Borrower Acknowledgment. The Borrower acknowledges that it has made the representations and warranties referred to in Section 3.1 with the intention of persuading the Lenders to
enter into the Financing Documents and that the Lenders have entered into the Financing Documents on the basis of, and in full reliance on, each of such representations and warranties. 
 Section 3.3 Representations and Warranties of the Lenders. Each of the Lenders represents and warrants to the Borrower as of the date
hereof and as of each date Warrants are granted pursuant to this Agreement, and agrees that: 
 (a) It is acquiring the
Warrants and the shares of Common Stock issued pursuant to the Warrants, whether upon exercise or otherwise (the “Warrant Shares”), solely for its account for investment and not with a view to or for sale or distribution of the
Warrants or Warrant Shares or any part thereof. Each of the Lenders also represents that the entire legal and beneficial interests of the Warrants and Warrant Shares such Lender is acquiring is being acquired for, and will be held for, its account
only. 
 (b) The Warrants and the Warrant Shares have not been registered under the Securities Act on the basis that no
distribution or public offering of the stock of the Borrower is to be effected. Each of the Lenders realizes that the basis for the exemptions may not be present, if notwithstanding its representations such Lender has a present intention of
acquiring the securities for a fixed or determinable period in the future, selling (in connection with a distribution or otherwise), granting any participation in, or otherwise distributing the Warrant Shares. None of the Lenders has such present
intention. Each of the Lenders understands (i) that the Warrant Shares are not registered under the Securities Act or qualified under applicable state securities laws on the ground that the issuance contemplated by the Warrants will be exempt
from the registration and qualifications requirements thereof and (ii) that the Borrower’s reliance on such exemptions is predicated on the representations set forth in this Section 3.3. 
 (c) It has such knowledge and experience in financial and business matters as to be capable of evaluating the merits and risks of its
investment and has the ability to bear the economic risks of its investment. 
 (d) The Warrants and the Warrant Shares must
be held indefinitely unless they are subsequently registered under the Securities Act or an exemption for such registration is available. 
  

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 (e) Neither the Warrants nor the Warrant Shares may be sold pursuant to Rule 144 adopted
under the Securities Act unless certain conditions are met, including, among other things, the existence of a public market for the shares, the availability of certain current public information about the Borrower, the resale following the required
holding period under Rule 144 and the number of shares being sold during any three month period not exceeding specified limitation. 
 (f) It will not make any disposition of all or any part of the Warrants or Warrant Shares until: 
 (i) There is then
in effect a registration statement under the Securities Act covering such proposed disposition and such disposition is made in accordance with said registration statement; or 
 (ii) Such Lender shall have notified the Borrower of the proposed disposition and, in the case of a sale or transfer in a so called
“4(1) and a half” transaction, shall have furnished counsel for the Borrower with an opinion of counsel, substantially in the form annexed as Exhibit C to the Warrant. The Borrower agrees that it will not require an opinion of counsel with
respect to transactions under Rule 144 of the Securities Act. 
 (g) All certificates evidencing the Warrant Shares may bear
the following legend. 
 “THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE SECURITIES MAY NOT BE SOLD, TRANSFERRED, ASSIGNED, PLEDGED, HYPOTHECATED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER SAID ACT, OR PURSUANT
TO AN EXEMPTION FROM REGISTRATION UNDER SAID ACT INCLUDING, WITHOUT LIMITATION, PURSUANT TO RULES 144 OR 144A UNDER SAID ACT OR PURSUANT TO A PRIVATE SALE EFFECTED UNDER APPLICABLE FORMAL OR INFORMAL SEC INTERPRETATION OR GUIDANCE, SUCH AS A
SO-CALLED “4(1) AND A HALF” SALE, SUBJECT TO DELIVERY OF AN OPINION, AS PROVIDED IN THE WARRANT, DATED AS OF             , 20    , ISSUED BY THE
COMPANY.” 
 “THE SALE, TRANSFER OR ASSIGNMENT OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE TERMS AND
CONDITIONS OF A CERTAIN FACILITY AGREEMENT DATED AS OF JUNE 17, 2009, AS AMENDED FROM TIME TO TIME, AMONG THE COMPANY AND THE LENDERS REFERRED TO THEREIN. COPIES OF SUCH AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE HOLDER OF
RECORD OF THIS CERTIFICATE TO THE SECRETARY OF THE COMPANY.” 
  

 14 

 (h) Such Lender is an “accredited investor” as defined in Regulation D
promulgated the Securities Act. 
 (i) Such Lender is a limited partnership or corporation duly organized and validly existing
under the laws of the jurisdiction of its formation. 
 (j) Each Financing Document to which it is a party has been duly
authorized, executed and delivered by such Lender and constitutes the valid and legally binding obligation of such Lender, enforceable in accordance with its terms, except as such enforceability may be limited by (i) applicable insolvency,
bankruptcy, reorganization, moratorium or other similar laws affecting creditors’ rights generally, and (ii) applicable equitable principles (whether considered in a proceeding at law or in equity). 
 Section 3.4 Lenders Acknowledgement. Each of the Lenders acknowledges that it has made the representations and warranties referred to
in Section 3.3 with the intention of persuading the Borrower to enter into the Financing Documents and that the Borrower has entered into the Financing Documents on the basis of, and in full reliance of, each of such representations and
warranties. Each of the Lenders also acknowledges that the representations and warranties made by the Borrower in Section 3.1, to the extent that they pertain to the Warrants or the Registration Rights Agreement (with the exception of
Subsection (d) of Section 3.1), are made solely to the extent, and will only survive for so long as, any of the Lenders remains a party to the Registration Rights Agreement or the Warrant. 
 ARTICLE IV 
 CONDITIONS OF
DISBURSEMENTS 
 Section 4.1 Conditions to Disbursement of the Loan. 
 (a) The obligation of the Lenders to make the Disbursement on the Disbursement Date shall be subject to the fulfillment of the following
conditions: (i) the Lenders shall have received a copy of customary closing documents evidencing the authorization of the Borrower to execute, deliver and perform each of the Financing Documents and to engage in the transactions contemplated
thereby and an opinion of Borrower’s counsel reasonably satisfactory to the Lenders and (ii) the representations and warranties of the Borrower in Section 3.1 shall be true and correct in all material respects as of the Disbursement
Date. 
 (b) Unless otherwise notified by the Borrower and without prejudice to the generality of this Section 4.1, the
right of the Lenders to require compliance with any condition under this Agreement which may be waived by the Lenders in respect of the Disbursement is expressly preserved for the purpose of any subsequent disbursement. 
  

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 ARTICLE V 
 PARTICULAR COVENANTS AND EVENTS OF DEFAULT 
 Section 5.1 Affirmative Covenants.
Unless the Requisite Lenders shall otherwise agree: 
 (a) The Borrower shall (i) maintain its existence and
qualification to do business in such jurisdictions as may be required to conduct its business, except where the failure to so maintain such qualification would not reasonably be expected to have a Material Adverse Effect and (ii) maintain all
approvals necessary for the Facility Documents to be in effect. 
 (b) The Borrower shall comply in all material respects with
all applicable laws, rules, regulations and orders of any Government Authority, except where the necessity of compliance therewith is contested in good faith by appropriate proceedings or where the failure to so comply, individually or in the
aggregate, would not reasonably be expected to have a Material Adverse Effect. 
 (c) The Borrower shall obtain, make and keep
in full force and effect all licenses, contracts, consents, approvals and authorizations from and registrations with Government Authorities that may be required to conduct its business, except to the extent that the failure to do so would not
reasonably be expected to have a Material Adverse Effect. 
 (d) The Borrower shall promptly notify the Lenders of the
occurrence of (i) any Default or Event of Default, (ii) any claims, litigation, arbitration, mediation or administrative or regulatory proceedings that are instituted or threatened against the Borrower; except for matters that,
individually or in the aggregate, would not reasonably be expected to have a Material Adverse Effect and (iii) each event which, at the giving of notice, lapse of time, determination of materiality or fulfillment of any other applicable
condition (or any combination of the foregoing), would constitute an event of default (however described) under any of the Facility Documents. 
 (e)(i) If the Borrower is not required to file reports pursuant to Section 13 or 15(d) of the Exchange Act, the Borrower will provide quarterly financial statements for itself and its Subsidiaries with 45 days
after the end of each quarter, and annual financial statements within 120 days after the end of each year; (ii) the Borrower will timely file with the SEC (subject to appropriate extensions made under Rule 12b-25 of the Exchange Act) any
annual, quarterly and other reports (other than current reports on Form 8-K) required pursuant to Section 13 or 15(d) of the Exchange Act prepared by the Borrower; and (iii) the Borrower and its Subsidiaries will provide to the Lenders
copies of all documents, reports, financial data and other information as the Lenders may reasonably request, and permit the Lenders to visit and inspect any of the properties of the Borrower and its Subsidiaries, and to discuss its and their
affairs, finances and accounts with its and their officers, all at such times during regular business hours as the Lenders may reasonably request. 
  

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 Section 5.2 Negative Covenants. So long as the aggregate outstanding principal amount
of the Loan exceeds five million Dollars ($5,000,000) and unless the Requisite Lenders shall otherwise agree: 
 (a) The
Borrower shall not (i) liquidate or dissolve, or (ii) enter into any consolidation, merger or reorganize, unless either (A) the Borrower is the surviving corporation, or (B) the Person formed by such consolidation or
reorganization or into which the Company is merged shall be a corporation, limited liability company, partnership or trust organized and validly existing under the laws of the United States of America, any state thereof or the District of Columbia,
and such resulting, surviving or transferee Person shall expressly assume the Obligations. 
 (b) The Borrower shall not
(i) enter into any partnership, joint venture, syndicate, pool, profit-sharing or royalty agreement, or engage in any transaction with an Affiliate (other than a Subsidiary), whereby its income or profits are shared with another Person (other
than a Subsidiary), other than such providing for the research, development or commercial exploitation of intellectual property, compounds, targets, programs, products, services or other assets or other than such transactions the Net Proceeds of
which are used to repay all or a portion of the Loan, (ii) enter into any management contract or similar arrangement whereby a substantial part of its business is managed by another Person, other than any partnership, joint venture or
collaboration arrangement pursuant to which the assets subject thereto are managed on joint basis with the other parties thereto, or (iii) distribute, or permit the distribution of, any assets of the Borrower or its Subsidiaries to any
shareholders of the Borrower or the holder of any equity interest in any Subsidiary of the Borrower or any of the Borrower’s Affiliates (other than the Borrower or a Subsidiary of the Borrower) in circumstances where the Borrower does not
receive fair value as determined in good faith by the Borrower; provided that royalties and other payments made by any partnership, joint venture, syndicate, pool, profit sharing or royalty agreement to the parties thereto shall not be deemed to be
a distribution of assets. 
 (c) The Borrower shall not (i) create, incur assume, guarantee or become liable with respect
to any indebtedness for borrowed money, other than Permitted Indebtedness, or (ii) voluntarily prepay any indebtedness, except (A) prepayments of the Loan or (B) prepayments of indebtedness in connection with extensions, refinancings,
replacements and renewals of any item of Permitted Indebtedness, provided that the principal amounts and premiums, if any, are not increased (other than the amount of any customary penalties, premiums and costs and expenses incurred therewith,
including any original issue discount). 
 (d) Borrower shall: (i) not, directly or indirectly, create, permit or suffer
to exist, and shall defend the Collateral against and take such other action as is necessary to remove, any Lien on the Collateral and (ii) defend title to the Collateral against the claims and demands of all persons claiming any interest
therein adverse to the Lenders, except in each case for Permitted Liens and for dispositions of assets not otherwise prohibited by this Agreement. 
  

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 Section 5.3 Reimbursement of Taxes. The Borrower shall pay all Taxes, duties, fees or
other charges payable on or in connection with the execution, issue, delivery, registration, notarization or enforcement of the Facility Documents and shall, upon notice from the Lenders, reimburse the Lenders for any such Taxes, duties, fees or
other charges paid by the Lenders thereon; provided, however, that notwithstanding the foregoing, under no circumstances shall the Borrower have any obligation to reimburse the Lenders for Excluded Taxes. 
 Section 5.4 Major Transaction Put. Following public announcement of a Major Transaction, the Lenders, in the exercise of their sole
discretion, may deliver a notice to the Borrower (the “Put Notice”), that the Final Payment (the “Put Price”) is immediately due and payable. If the Lenders deliver a Put Notice, then on the Major Transaction Put
Date, the Borrower shall pay the Put Price to the Lenders and the Obligations shall terminate. 
 Section 5.5 General Acceleration
Provision upon Events of Default. If one or more of the events specified in this Section 5.5 (each an “Event of Default”) shall have happened and is continuing, the Requisite Lenders, by written notice to the
Borrower, (any such notice, an “Acceleration Notice”), may declare the principal of, accrued interest on, the Loan or any part thereof (together with any other amounts accrued or payable under this Agreement) to be, and the same
shall thereupon become, immediately due and payable, without any further notice and without any presentment, demand, or protest of any kind, all of which are hereby expressly waived by the Borrower, and take any further action available at law or in
equity, including, without limitation, the sale of the Loan and all other rights acquired in connection with the Loan: 
 (a)
Borrower fails to pay (i) principal when due under the Loan or the Notes, or (ii) any other amounts due under the Loan or the Notes within five (5) Business Days of their due date. 
 (b) The Borrower shall have failed to comply in any material respect with the due observance or performance of any other covenant
contained in this Agreement or any Note, such failure could reasonably be expected to result in a Material Adverse Effect and such failure shall not have been cured by Borrower within 60 days after receiving written notice of such failure.

 (c) Any representation or warranty made by the Borrower in any Financing Document shall have been incorrect, false or
misleading in any material respect as of the date it was made, deemed made, reaffirmed or confirmed and as a result thereof the Borrower could reasonably be expected to incur a Material Adverse Effect. 
 (d)(i) The Borrower shall generally be unable to pay its debts as such debts become due, or shall admit in writing its inability to pay
its debts as they come due or shall make a general assignment for the benefit of creditors; (ii) the Borrower shall declare a moratorium on the payment of its debts; (iii) the commencement by the Borrower of proceedings to be adjudicated
bankrupt or insolvent, or the consent by it to the commencement of bankruptcy or insolvency proceedings against it, or the filing by it of a petition or answer or consent seeking reorganization, intervention or other similar relief under any
applicable law, or the consent by it to the filing of any such petition or to the appointment of an intervenor, receiver, liquidator, assignee, trustee, sequestrator (or other similar official) or of any substantial part of its assets; (iv) the
commencement against the Borrower or any 

  

 18 

 
substantial part of its assets of a proceeding in any court of competent jurisdiction under any bankruptcy or other applicable law (as now or hereafter in
effect) seeking its liquidation, winding up, dissolution, reorganization, arrangement, adjustment, or the appointment of an intervenor, receiver, liquidator, assignee, trustee, sequestrator (or other similar official), and any such proceeding shall
continue undismissed, or any order, judgment or decree approving or ordering any of the foregoing shall continue unstayed or otherwise in effect, for a period of ninety (90) days; or (vi) any other event shall have occurred which under any
applicable law would have an effect analogous to any of those events listed above in this subsection. 
 (e) One or more
judgments against the Borrower taken as a whole or attachments against any of its property, which in the aggregate exceed $1,000,000 (net of any anticipated insurance proceeds), is not stayed on appeal, discharged, bonded or dismissed for a period
of sixty (60) days from the date of entry of such judgment. 
 (f) The Borrower repudiates any of the Facility Documents
or challenges the validity or enforceability of the Facility Documents. 
 (g) The validity of any material provision of any
of the Financing Documents shall be contested by any legislative, executive or judicial body of any United States jurisdiction, or any treaty, law, regulation, communiqué, decree, ordinance or policy of any jurisdiction shall purport to
render any material provision of any Financing Document invalid or unenforceable or shall purport to prevent or materially delay the performance or observance by the Borrower of the Obligations and the Parties are unable to negotiate a replacement
provision pursuant to Section 6.7 below. 
 (h) There is a failure to perform in any agreement to which the Borrower is a
party with a third party or parties resulting in the acceleration of the maturity of any indebtedness for borrowed money in an amount in excess of $500,000 and such acceleration is not rescinded, or such indebtedness is not contested in good faith
or paid or otherwise discharged, within thirty (30) days after such acceleration. 
 (i) An Event of Default (as such
term is defined in the Warrants) occurs pursuant to any Warrant held by a Lender. 
 Section 5.6 Automatic Acceleration on
Dissolution or Bankruptcy. Notwithstanding any other provisions of this Agreement, if an Event of Default under Section 5.5(d) shall occur, the principal of the Loan (together with any other amounts accrued or payable under this
Agreement) shall thereupon become immediately due and payable without any presentment, demand, protest or notice of any kind, all of which are hereby expressly waived by the Borrower. 
 Section 5.7 Recovery of Amounts Due. If an Event of Default has occurred and is continuing and, other than in the case of an Event of
Default under Section 5.5(d), the Lenders shall have sent an Acceleration Notice, the Borrower hereby authorizes the Lenders to proceed, to the fullest extent permitted by applicable law, without prior notice, by right of set-off, banker’s
lien or counterclaim, against any moneys or other assets of the Borrower to the full extent of all amounts payable to the Lenders. 
  

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 ARTICLE VI 
 MISCELLANEOUS 
 Section 6.1 Notices. Any notice, request or other communication to
be given or made under this Agreement shall be in writing. Such notice, request or other communication shall be deemed to have been duly given or made when it shall be delivered by hand, international courier (confirmed by facsimile), or facsimile
(with a hard copy delivered within two (2) Business Days) to the Party to which it is required or permitted to be given or made at such Party’s address specified below or at such other address as such Party shall have designated by notice
to the other Parties. 
 For the Borrower: 
 Arena Pharmaceuticals, Inc. 
 6166 Nancy Ridge Drive 
 San Diego, CA 92121 
 Attention: Chief
Financial Officer and General Counsel 
 Facsimile: (858) 677-0065 
 with a courtesy copy (not constituting notice) to: 
 Cooley Godward Kronish LLP 
 4401 Eastgate Mall 
 San Diego, CA 92121 
 Attention: Steven Przesmicki 
 Facsimile: (858) 550-6420 
 For the
Lenders c/o: 
 Deerfield Private Design Fund, L.P. 
 780 Third Avenue, 37th Floor 
 New York, New
York 10017 
 Attention: James E. Flynn 
 Facsimile: (212) 573-8111 
 with a courtesy copy (not constituting notice) to: 
 Katten Muchin Rosenman LLP 
 575 Madison
Avenue 
 New York, New York 10022-2585 
 Facsimile: (212) 894-5827 
 Attention: Robert I. Fisher 
  

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 Section 6.2 Waiver of Notice. Whenever any notice is required to be given to the Lenders or
the Borrower under the any of the Financing Documents, a waiver thereof in writing signed by the person or persons entitled to such notice, whether before or after the time stated therein, shall be deemed equivalent to the giving of such notice.
 
 Section 6.3 Reimbursement of Legal and Other Expenses. If any amount owing to the Lenders under any Financing
Document shall be collected through enforcement of this Agreement, any refinancing or restructuring of the Loan in the nature of a work-out, settlement, negotiation, or any process of law, or shall be placed in the hands of third Persons for
collection, the Borrower shall pay (in addition to all monies then due in respect of the Loan or otherwise payable under any Financing Document) reasonable, documented attorneys’ and other fees and expenses reasonably incurred in respect of
such collection. 
 Section 6.4 Applicable Law and Consent to Non-Exclusive New York Jurisdiction. This Agreement shall be
governed by and construed in accordance with the laws of the State of New York, without giving effect to the conflicts of laws principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of such State. 
 (a) Each Party hereby irrevocably submits to the jurisdiction of the state and federal courts sitting in The City of New York, borough of
Manhattan or the County of San Diego for the adjudication of any dispute hereunder or in connection herewith or with any transaction contemplated hereby or discussed herein, and hereby irrevocably waives, and agrees not to assert in any suit, action
or other proceeding, any claim that it is not personally subject to the jurisdiction of any such court, or that such court, action or other proceeding is improper. Final non-appeal able judgment against any Party in any such action, suit or other
proceeding shall be conclusive and may be enforced in any other jurisdiction by suit on the judgment. Nothing contained in any Financing Document shall affect the right of any Party to commence legal proceedings in any court having jurisdiction, or
concurrently in more than one jurisdiction, or to serve process, pleadings and other legal papers upon the other Party(ies) in any manner authorized by the laws of any such jurisdiction. Each Party irrevocably waives, to the fullest extent permitted
by applicable law, any objection which it may now or hereafter have to the laying of venue of any such action, suit or other proceeding brought in the courts in the State of New York, in the County of San Diego or in the United States District Court
for the Southern District of New York, and any claim that any such action, suit or other proceeding brought in any such court has been brought in an inconvenient forum. 
 (b) EACH PARTY HEREBY WAIVES ANY AND ALL RIGHTS TO DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF ANY
FINANCING DOCUMENT OR THE TRANSACTIONS CONTEMPLATED BY ANY FINANCING DOCUMENT. 
 (c) To the extent that the Parties may, in
any suit, action or other proceeding brought in any court arising out of or in connection with any Financing Document, be entitled to the benefit of any provision of law requiring the Borrower or the Lenders, as applicable, in such suit, action or
other proceeding to post security for the costs of the Borrower or the Lenders, as applicable, or to post a bond or to take similar action, the Parties hereby irrevocably waive such benefit, in each case to the fullest extent now or hereafter
permitted under any applicable laws. 
  

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 Section 6.5 Successor and Assigns. This Agreement shall bind and inure to the
respective successors and assigns of the Parties; provided that any assignments of, or participations in, the Notes shall be in the aggregate principal amounts of not less than the lesser of (a) two million Dollars ($2,000,000) or (b) the
aggregate principal amount of the Notes. The Borrower may not assign or otherwise transfer all or any part of its rights under this Agreement or the Obligations without the prior written consent of the Lenders. Notwithstanding anything to the
contrary herein, if any assignment or participation is to any Person that is not a “United States person” within the meaning of Section 7701(a)(30) of the Code, then such Person shall submit to the Borrower, on or before the date of
such assignment or participation an IRS Form W-8BEN (or any successor form) certifying as to such Person’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with
respect to all payments to be made to such Person. Any attempted assignment or participation in violation of this Section 6.5 shall be void and of no further effect. 
 Section 6.6 Entire Agreement. The Financing Documents contain the entire understanding of the Parties with respect to the matters covered thereby and supersede any and all other written and oral
communications, negotiations, commitments and writings with respect thereto. This Agreement may be amended, and any provision may be waived, by a writing signed by the Borrower and the Requisite Lenders. 
 Section 6.7 Severability. If any provision contained in this Agreement shall be invalid, illegal or unenforceable in any respect under
any law, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby. The Parties shall endeavor in good faith negotiations to replace the invalid, illegal or unenforceable provisions
with valid provisions the economic effect of which comes as close as possible to that of the invalid, illegal or unenforceable provision. 
 Section 6.8 Counterparts. This Agreement may be executed in several counterparts, and by each Party on separate counterparts, each of which shall be deemed an original, but all of which together shall constitute one and
the same agreement. Facsimile signatures shall be treated as original signatures. 
 Section 6.9 Survival. 
 (a) This Agreement and all agreements, representations and warranties made in the Facility Documents, and in any document, certificate or
statement delivered pursuant thereto or in connection therewith shall be considered to have been relied upon by the Parties and shall survive the execution and delivery of this Agreement and the making of the Loan regardless of any investigation
made by any Party or on its behalf, and shall continue in force until all amounts payable under the Facility Documents shall have been fully paid in accordance with the provisions hereof and thereof, and the Lenders shall not be deemed to have
waived, by reason of making the Loan, any Default that may arise by reason of such representation or warranty proving to have been false or misleading, notwithstanding that the Lenders may have had notice or knowledge of any such Default or may have
had notice or knowledge that such representation or warranty was false or misleading at the time the Disbursement was made hereunder. 
  

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 (b) The obligations of the Borrower under Section 2.6 and the obligations of the
Borrower and the Lenders under this Section 6.9 hereof shall survive and remain in full force and effect regardless of the repayment of the Loan or the termination of this Agreement or any provision hereof. 
 Section 6.10 Waiver. Neither the failure of, nor any delay on the part of, any Party in exercising any right, power or privilege
hereunder, or under any agreement, document or instrument mentioned herein, shall operate as a waiver thereof, nor shall any single or partial exercise of any right, power or privilege hereunder, or under any agreement, document or instrument
mentioned herein, preclude other or further exercise thereof or the exercise of any other right, power or privilege; nor shall any waiver of any right, power, privilege or default hereunder, or under any agreement, document or instrument mentioned
herein, constitute a waiver of any other right, power, privilege or default or constitute a waiver of any default of the same or of any other term or provision. No course of dealing and no delay in exercising, or omission to exercise, any right,
power or remedy accruing to the Lenders upon any default under this Agreement or any other agreement shall impair any such right, power or remedy or be construed to be a waiver thereof or an acquiescence therein; nor shall the action of the Lenders
in respect of any such default, or any acquiescence by it therein, affect or impair any right, power or remedy of the Lenders in respect of any other default. All rights and remedies herein provided are cumulative and not exclusive of any rights or
remedies otherwise provided by law. 
 Section 6.11 Indemnity. 
 (a) The Parties shall, at all times, indemnify and hold each other harmless (the “Indemnity”) and each of their
respective directors, partners, officers, employees, agents, counsel and advisors (each, an “Indemnified Person”) in connection with any losses, claims (including the cost of defending against such claims), damages, liabilities,
penalties, or other expenses which may be incurred by or asserted against an Indemnified Person arising out of any investigation, litigation or proceeding relating to the Facility Documents (each, a “Loss”), the extension of credit
hereunder or the Loan or the use or intended use of the Loan. The Indemnity shall not apply to the extent that a court or arbitral tribunal with jurisdiction over the subject matter of the Loss, and over the Lenders or the Borrower, as applicable,
and such other Indemnified Person that had an adequate opportunity to defend its interests, determines that such Loss resulted from the gross negligence or willful misconduct of the Indemnified Person, which determination results in a final,
non-appealable judgment or decision of a court or tribunal of competent jurisdiction. The Indemnity is independent of and in addition to any other agreement of any Party under any Financing Document to pay any amount to the Lenders or the Borrower,
as applicable, and any exclusion of any obligation to pay any amount under this subsection shall not affect the requirement to pay such amount under any other section hereof or under any other agreement. 
 (b) Without prejudice to the survival of any other agreement of any of the Parties hereunder, the agreements and the obligations of the
Parties contained in this Section 6.11 shall survive the termination of each other provision hereof and the payment of all amounts payable to the Lenders hereunder. 
  

 23 

 Section 6.12 No Usury. The Financing Documents are hereby expressly limited so that in
no contingency or event whatsoever, whether by reason of acceleration or otherwise, shall the amount paid or agreed to be paid to the Lenders for the Loan exceed the maximum amount permissible under applicable law. If from any circumstance
whatsoever fulfillment of any provision hereof, at the time performance of such provision shall be due, shall involve transcending the limit of validity prescribed by law, then, ipso facto, the obligation to be fulfilled shall be reduced to the
limit of such validity, and if from any such circumstance the Lenders shall ever receive anything which might be deemed interest under applicable law, that would exceed the highest lawful rate, such amount that would be deemed excessive interest
shall be applied to the reduction of the principal amount owing on account of the Loan, or if such deemed excessive interest exceeds the unpaid balance of principal of the Loan, such deemed excess shall be refunded to the Borrower. All sums paid or
agreed to be paid to the Lenders for the Loan shall, to the extent permitted by applicable law, be deemed to be amortized, prorated, allocated and spread throughout the full term of the Loan until payment in full so that the deemed rate of interest
on account of the Loan is uniform throughout the term thereof. The terms and provisions of this paragraph shall control and supersede every other provision of this Agreement and the Notes. 
 Section 6.13 Further Assurances. From time to time, each Party hereto shall perform any and all acts and execute and deliver to the
other Party such additional documents as may be necessary or as requested by the other Party to carry out the purposes of any Financing Document or to preserve and protect such other Party’s rights as contemplated therein. 
 Section 6.14 Termination. The Borrower may by written notice to the Lenders terminate this Agreement upon repayment of all outstanding
principal of the Loan (together with any other amounts accrued and unpaid under this Agreement), whereupon the Borrower’s Obligations shall terminate subject to the provisions of Section 6.11(b). 
 [SIGNATURE PAGE FOLLOWS] 
  

 24 

 IN WITNESS WHEREOF, the Parties, acting through their duly authorized representatives, have caused this
Agreement to be signed in their respective names as of the date first above written. 
  

									
	 BORROWER:
 ARENA PHARMACEUTICALS,
INC.
	 		 	 LENDER:
 DEERFIELD PRIVATE
DESIGN FUND, L.P.

					
	By:	 	 /s/    Jack Lief
	 		 	By:	 	 /s/    James E. Flynn

	Name:	 	Jack Lief	 		 	Name:	 	James E. Flynn
	Title:	 	President and CEO	 		 	Title:	 	General Partner
			
	 LENDER:
 DEERFIELD PRIVATE
DESIGN
 INTERNATIONAL, L.P.
	 		 	 LENDER:
 DEERFIELD PARTNERS,
L.P.
  

					
	By:	 	 /s/    James E. Flynn
	 		 	By:	 	 /s/    James E. Flynn

	Name:	 	James E. Flynn	 		 	Name:	 	James E. Flynn
	Title:	 	General Partner	 		 	Title:	 	General Partner
			
	 LENDER:
 DEERFIELD INTERNATIONAL
LIMITED
	 		 	 LENDER:
 DEERFIELD SPECIAL
SITUATIONS FUND, L.P.

					
	By:	 	 /s/    James E. Flynn
	 		 	By:	 	 /s/    James E. Flynn

	Name:	 	James E. Flynn	 		 	Name:	 	James E. Flynn
	Title:	 	Director	 		 	Title:	 	General Partner
				
	 LENDER:
 DEERFIELD SPECIAL
SITUATIONS FUND
 INTERNATIONAL LIMITED
	 		 		 	
					
	By:	 	 /s/    James E. Flynn
	 		 		 	
	Name:	 	James E. Flynn	 		 		 	
	Title:	 	Director	 		 		 	

 SCHEDULE 1 
 LENDERS 
  

						
	 Lender
	  	Principal Amount of
Note	 	Number of Shares of
Common Stock Underlying
Warrant
	Deerfield Private Design Fund, L.P.	  	$	16,852,000	 	4,718,560
	Deerfield Private Design International, L.P.	  	$	27,148,000	 	7,601,440
	Deerfield Partners, L.P.	  	$	19,800,000	 	5,544,000
	Deerfield International Limited	  	$	30,200,000	 	8,456,000
	Deerfield Special Situations Fund, L.P.	  	$	2,112,000	 	591,360
	Deerfield Special Situations Fund International Limited	  	$	3,888,000	 	1,088,640
	 Total
	  	$	100,000,000	 	28,000,000

  

 1 

 SCHEDULE 2 
 FORM OF EVIDENCE OF DISBURSEMENT 
 [LETTERHEAD OF THE BORROWER] 
 [Date] 
 Ladies and Gentlemen: 
  

	 	Re:	Disbursement Receipt 

 Arena Pharmaceuticals, Inc. (the
“Borrower”) hereby acknowledges receipt of the sum of $100,000,000 disbursed to it by Deerfield Private Design Fund, L.P., Deerfield Private Design International, L.P., Deerfield Partners, L.P. and Deerfield International Limited
(together the “Lenders”) under the Loan provided for in the Facility Agreement, dated as of June 17, 2009, between the Borrower and the Lenders. 
  

			
	Yours faithfully,
	
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	  

	Title	 	  

  

 2 

 EXHIBIT A-1 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield Private Design International, L.P. (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds, on the
dates provided in the Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement dated as
of June 17, 2009 among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder.
Capitalized terms used herein and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note shall bear interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the
Facility Agreement. The outstanding principal amount of this Note shall be due and payable in full on the Final Payment Date. 
 If an Event
of Default has occurred and is continuing, this Note shall, at the Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly
provided in the Facility Agreement. The Maker shall be responsible for the payment of certain present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks,
clearing houses, or any other financial institution, in connection with making any payments hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection, including, without limitation, all reasonable, documented legal expenses and attorneys’
fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations
represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the Facility Agreement or the performance of the obligations under this Note and/or the Facility
Agreement. No renewal or extension of this Note or the Facility Agreement, no 

  

 3 

 
release of any Person primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the
enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any
default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance
with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE
OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY
IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY
CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO
DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable to contracts made and to be performed in such State, without giving effect to the conflicts of laws
principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is
held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder
that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as “portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of
Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and (y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under
Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain
from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee noteholder that is not a United
States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and 

  

 4 

 
will not be as long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of
Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the
date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no longer valid) until all amounts due under this Note have been paid in full, such noteholder shall provide the Maker with a
properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding (or any successor form prescribed by the IRS), certifying as to such
noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder hereunder; (iv) if an event occurs that
would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS Form W-8BEN (or successor form) previously submitted by such noteholder to the Maker, such noteholder will so inform the
Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of such event; and (v) such noteholder will not assign or otherwise transfer this Note or any of its rights hereunder
except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer
of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the transferee, or the Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee
denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is maintaining a record ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as
such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of this Note shall be binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided,
however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to any noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Code,
then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor form) certifying as to such noteholder’s status for purposes of determining exemption from United States withholding
tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note (or other instrument). Any attempted transfer in violation of the relevant provisions of this Note shall be void and of
no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in accordance with this Note, the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note
and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all payments to be made under this Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and not a bearer instrument and the provisions of this Note are to be interpreted accordingly. This Note is intended to be
registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a transfer pursuant to the Facility Agreement and this Note, to the transferee identified in the record of ownership of this
Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the provisions hereof. 
  

 5 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 6 

 EXHIBIT A-2 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield Private Design Fund, L.P. (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds on the dates provided
in the Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement dated as of
June 17, 2009 among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder. Capitalized
terms used herein and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note shall bear interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the
Facility Agreement. The outstanding principal amount of this Note shall be due and payable in full on the Final Payment Date. 
 If an Event
of Default has occurred and is continuing, this Note shall, at the Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly
provided in the Facility Agreement. The Maker shall be responsible for the payment of certain present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks,
clearing houses, or any other financial institution, in connection with making any payments hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection, including, without limitation, all reasonable, documented legal expenses and attorneys’
fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations
represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the Facility Agreement or the performance of the obligations under this Note and/or the Facility
Agreement. No renewal or extension of this Note or the Facility Agreement, no 

  

 7 

 
release of any Person primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the
enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any
default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance
with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE
OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY
IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY
CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO
DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable to contracts made and to be performed in such State, without giving effect to the conflicts of laws
principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is
held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder
that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as “portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of
Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and (y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under
Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain
from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee noteholder that is not a United
States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of

  

 8 

 
Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in
full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no longer valid) until all amounts due
under this Note have been paid in full, such noteholder shall provide the Maker with a properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax
Withholding (or any successor form prescribed by the IRS), certifying as to such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all
payments to be made to such noteholder hereunder; (iv) if an event occurs that would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS Form W-8BEN (or successor form)
previously submitted by such noteholder to the Maker, such noteholder will so inform the Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of such event; and (v) such
noteholder will not assign or otherwise transfer this Note or any of its rights hereunder except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the transferee, or the
Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is maintaining a record
ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of this Note shall be
binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided, however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to any noteholder that
is not a “United States person” within the meaning of Section 7701(a)(30) of the Code, then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor form) certifying as to
such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note (or other instrument).
Any attempted transfer in violation of the relevant provisions of this Note shall be void and of no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in accordance with this Note,
the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all payments to be made under this
Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and not a bearer instrument and the
provisions of this Note are to be interpreted accordingly. This Note is intended to be registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a transfer pursuant to the Facility
Agreement and this Note, to the transferee identified in the record of ownership of this Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the provisions hereof. 
  

 9 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 10 

 EXHIBIT A-3 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield Partners, L.P. (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds, on the dates provided in the
Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement dated as of June 17, 2009
among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder. Capitalized terms used herein
and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note shall bear
interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the Facility Agreement. The outstanding principal amount of this Note
shall be due and payable in full on the Final Payment Date. 
 If an Event of Default has occurred and is continuing, this Note shall, at the
Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly provided in the Facility Agreement. The Maker shall be responsible for the payment of certain
present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks, clearing houses, or any other financial institution, in connection with making any payments
hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection,
including, without limitation, all reasonable, documented legal expenses and attorneys’ fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the
Facility Agreement or the performance 

  

 11 

 
of the obligations under this Note and/or the Facility Agreement. No renewal or extension of this Note or the Facility Agreement, no release of any Person
primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power
under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by
the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the
exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT
OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE
COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY
AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS
CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable
to contracts made and to be performed in such State, without giving effect to the conflicts of laws principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal
Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as
“portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and
(y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the
Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information
reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee 

  

 12 

 
noteholder that is not a United States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and will not be as
long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under
this Note have not been paid in full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no
longer valid) until all amounts due under this Note have been paid in full, such noteholder shall provide the Maker with a properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of
Beneficial Owner for United States Tax Withholding (or any successor form prescribed by the IRS), certifying as to such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and
backup withholding with respect to all payments to be made to such noteholder hereunder; (iv) if an event occurs that would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS
Form W-8BEN (or successor form) previously submitted by such noteholder to the Maker, such noteholder will so inform the Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of
such event; and (v) such noteholder will not assign or otherwise transfer this Note or any of its rights hereunder except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the
transferee, or the Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is
maintaining a record ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of
this Note shall be binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided, however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to
any noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Code, then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor
form) certifying as to such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note
(or other instrument). Any attempted transfer in violation of the relevant provisions of this Note shall be void and of no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in
accordance with this Note, the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all
payments to be made under this Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and
not a bearer instrument and the provisions of this Note are to be interpreted accordingly. This Note is intended to be registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a
transfer pursuant to the Facility Agreement and this Note, to the transferee identified in the record of ownership of this Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the
provisions hereof. 
  

 13 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 14 

 EXHIBIT A-4 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield International Limited (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds, on the dates provided in
the Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement dated as of June 17,
2009 among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder. Capitalized terms used
herein and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note
shall bear interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the
Facility Agreement. The outstanding principal amount of this Note shall be due and payable in full on the Final Payment Date. 
 If an Event
of Default has occurred and is continuing, this Note shall, at the Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly
provided in the Facility Agreement. The Maker shall be responsible for the payment of certain present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks,
clearing houses, or any other financial institution, in connection with making any payments hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection, including, without limitation, all reasonable, documented legal expenses and attorneys’
fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations
represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the Facility Agreement or the performance of the obligations under this Note and/or the Facility
Agreement. No renewal or extension of this Note or the Facility Agreement, no 

  

 15 

 
release of any Person primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the
enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any
default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance
with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE
OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY
IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY
CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO
DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable to contracts made and to be performed in such State, without giving effect to the conflicts of laws
principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is
held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder
that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as “portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of
Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and (y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under
Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain
from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee noteholder that is not a United
States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of

  

 16 

 
Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in
full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no longer valid) until all amounts due
under this Note have been paid in full, such noteholder shall provide the Maker with a properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax
Withholding (or any successor form prescribed by the IRS), certifying as to such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all
payments to be made to such noteholder hereunder; (iv) if an event occurs that would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS Form W-8BEN (or successor form)
previously submitted by such noteholder to the Maker, such noteholder will so inform the Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of such event; and (v) such
noteholder will not assign or otherwise transfer this Note or any of its rights hereunder except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the transferee, or the
Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is maintaining a record
ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of this Note shall be
binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided, however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to any noteholder that
is not a “United States person” within the meaning of Section 7701(a)(30) of the Code, then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor form) certifying as to
such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note (or other instrument).
Any attempted transfer in violation of the relevant provisions of this Note shall be void and of no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in accordance with this Note,
the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all payments to be made under this
Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and not a bearer instrument and the
provisions of this Note are to be interpreted accordingly. This Note is intended to be registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a transfer pursuant to the Facility
Agreement and this Note, to the transferee identified in the record of ownership of this Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the provisions hereof. 
  

 17 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 18 

 EXHIBIT A-5 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield Special Situations Fund, L.P. (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds, on the dates
provided in the Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement dated as of
June 17, 2009 among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder. Capitalized
terms used herein and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note shall bear interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the
Facility Agreement. The outstanding principal amount of this Note shall be due and payable in full on the Final Payment Date. 
 If an Event
of Default has occurred and is continuing, this Note shall, at the Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly
provided in the Facility Agreement. The Maker shall be responsible for the payment of certain present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks,
clearing houses, or any other financial institution, in connection with making any payments hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection, including, without limitation, all reasonable, documented legal expenses and attorneys’
fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations
represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the Facility Agreement or the performance of the obligations under this Note and/or the Facility
Agreement. No renewal or extension of this Note or the Facility Agreement, no 

  

 19 

 
release of any Person primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the
enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any
default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance
with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE
OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY
IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY
CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO
DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable to contracts made and to be performed in such State, without giving effect to the conflicts of laws
principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is
held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder
that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as “portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of
Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and (y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under
Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain
from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee noteholder that is not a United
States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of

  

 20 

 
Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in
full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no longer valid) until all amounts due
under this Note have been paid in full, such noteholder shall provide the Maker with a properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax
Withholding (or any successor form prescribed by the IRS), certifying as to such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all
payments to be made to such noteholder hereunder; (iv) if an event occurs that would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS Form W-8BEN (or successor form)
previously submitted by such noteholder to the Maker, such noteholder will so inform the Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of such event; and (v) such
noteholder will not assign or otherwise transfer this Note or any of its rights hereunder except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the transferee, or the
Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is maintaining a record
ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of this Note shall be
binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided, however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to any noteholder that
is not a “United States person” within the meaning of Section 7701(a)(30) of the Code, then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor form) certifying as to
such noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note (or other instrument).
Any attempted transfer in violation of the relevant provisions of this Note shall be void and of no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in accordance with this Note,
the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all payments to be made under this
Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and not a bearer instrument and the
provisions of this Note are to be interpreted accordingly. This Note is intended to be registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a transfer pursuant to the Facility
Agreement and this Note, to the transferee identified in the record of ownership of this Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the provisions hereof. 
  

 21 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 22 

 EXHIBIT A-6 
 FORM OF NOTE 
 PROMISSORY NOTE 
             , 200   
 FOR VALUE RECEIVED, ARENA PHARMACEUTICALS, INC., a Delaware corporation (the “Maker”), by means of this Promissory Note (this “Note”), hereby unconditionally promises to pay to
Deerfield Special Situations Fund International Limited (the “Payee”), the principal amount of $[        ], in lawful money of the United States of America and in immediately available funds,
on the dates provided in the Facility Agreement referred to below. 
 This Note is a “Note” referred to in the Facility Agreement
dated as of June 17, 2009 among the Maker, the Payee and the other parties thereto (as modified and supplemented and in effect from time to time, the “Facility Agreement”), with respect to the Loan made by the Payee thereunder.
Capitalized terms used herein and not expressly defined in this Note shall have the respective meanings assigned to them in the Facility Agreement. 
 This Note shall bear interest on the principal amount hereof, as such principal amount may be decreased, at the rates and pursuant to the provisions set forth in the Facility Agreement. 
 The Maker shall make all payments to the Payee of interest and principal under this Note in the manner provided in and otherwise in accordance with the
Facility Agreement. The outstanding principal amount of this Note shall be due and payable in full on the Final Payment Date. 
 If an Event
of Default has occurred and is continuing, this Note shall, at the Payee’s option exercised in accordance with the applicable provisions of the Facility Agreement, become immediately due and payable. 
 All payments of any kind due to the Payee from the Maker pursuant to this Note shall be made in the full face amount thereof, except as expressly
provided in the Facility Agreement. The Maker shall be responsible for the payment of certain present or future taxes as set forth in the Facility Agreement. The Maker shall pay all and any costs (administrative or otherwise) imposed by banks,
clearing houses, or any other financial institution, in connection with making any payments hereunder, except for any costs imposed by the Payee’s banking institutions. 
 The Maker shall pay all reasonable costs of collection, including, without limitation, all reasonable, documented legal expenses and attorneys’
fees, paid or incurred by the Payee in collecting and enforcing this Note. 
 The Maker and every endorser of this Note, or the obligations
represented hereby, expressly waives presentment, protest, demand, notice of dishonor or default, and notice of any kind with respect to this Note and the Facility Agreement or the performance of the obligations under this Note and/or the Facility
Agreement. No renewal or extension of this Note or the Facility Agreement, no 

  

 23 

 
release of any Person primarily or secondarily liable on this Note or the Facility Agreement, including the Maker and any endorser, no delay in the
enforcement of payment of this Note or the Facility Agreement, and no delay or omission in exercising any right or power under this Note or the Facility Agreement shall affect the liability of the Maker or any endorser of this Note. 
 No delay or omission by the Payee in exercising any power or right hereunder shall impair such right or power or be construed to be a waiver of any
default, nor shall any single or partial exercise of any power or right hereunder preclude the full exercise thereof or the exercise of any other power or right. This Note may be prepaid in whole or in part without premium or penalty in accordance
with the provisions of the Facility Agreement. 
 THIS NOTE, AND ANY RIGHTS OF THE PAYEE ARISING OUT OF OR RELATING TO THIS NOTE, MAY, AT THE
OPTION OF THE PAYEE, BE ENFORCED BY THE PAYEE IN THE COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE SOUTHERN DISTRICT OF THE STATE OF NEW YORK OR IN ANY OTHER COURTS HAVING JURISDICTION. FOR THE BENEFIT OF THE PAYEE, THE MAKER HEREBY
IRREVOCABLY AGREES THAT ANY LEGAL ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE MAY BE BROUGHT IN THE COURTS OF THE STATE OF NEW YORK OR OF THE UNITED STATES OF AMERICA FOR THE SOUTHERN DISTRICT OF NEW YORK, AND HEREBY
CONSENTS THAT PERSONAL SERVICE OF SUMMONS OR OTHER LEGAL PROCESS MAY BE MADE AS SET FORTH IN SECTION 6.4 OF THE FACILITY AGREEMENT, WHICH SERVICE THE MAKER AGREES SHALL BE SUFFICIENT AND VALID. THE MAKER HEREBY WAIVES ANY AND ALL RIGHTS TO
DEMAND A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE OR THE TRANSACTIONS CONTEMPLATED BY THIS NOTE. 
 This Note shall be governed by, and construed in accordance with, the laws of the State of New York applicable to contracts made and to be performed in such State, without giving effect to the conflicts of laws
principles thereof other than Sections 5-1401 and 5-1402 of the General Obligations Law of the State of New York. 
 Whenever this Note is
held by a noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the “Code”), then it is the intention of the Maker and such noteholder
that (x) all interest accrued and paid on this Note will qualify for exemption from United States withholding tax as “portfolio interest” because this Note is an obligation which is in “registered form” within the meaning of
Sections 871(h)(2)(B) and 881(c)(2)(B) of the Code and the applicable Treasury Regulations promulgated thereunder, and (y) as such, all interest accrued and paid on this Note will be exempt from United States information reporting under
Sections 6041 and 6049 of the Code and United States backup withholding under Section 3406 of the Code. The Maker and the Payee shall reasonably cooperate with one another, and execute and file such forms or other documents, or do or refrain
from doing such other acts, as may be required, to secure such exemptions from United States withholding tax, information reporting, and backup withholding. In furtherance of the foregoing, any transferee or assignee noteholder that is not a United
States person shall represent, warrant and covenant to the Maker that (i) such noteholder is not, and 

  

 24 

 
will not be as long as any amounts due under this Note have not been paid in full, a “United States person,” within the meaning of
Section 7701(a)(30) of the Code; (ii) such noteholder is not, and will not be as long as any amounts due under this Note have not been paid in full, a person described in Section 881(c)(3) of the Code; (iii) on or prior to the
date of transfer or assignment (and on or prior to the date the form provided pursuant to this clause (iii) is no longer valid) until all amounts due under this Note have been paid in full, such noteholder shall provide the Maker with a
properly executed U.S. Internal Revenue Service (“IRS”) Form W-8BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding (or any successor form prescribed by the IRS), certifying as to such
noteholder’s status for purposes of determining exemption from United States withholding tax, information reporting and backup withholding with respect to all payments to be made to such noteholder hereunder; (iv) if an event occurs that
would require a change in the exempt status of such noteholder or any of the other information provided on the most recent IRS Form W-8BEN (or successor form) previously submitted by such noteholder to the Maker, such noteholder will so inform the
Maker in writing (or by submitting to the Maker a new IRS Form W-8BEN or successor form) within 30 days after the occurrence of such event; and (v) such noteholder will not assign or otherwise transfer this Note or any of its rights hereunder
except in accordance with the provisions hereof. 
 In order to qualify as a “registered note” for purposes of the Code, transfer
of this Note may be effected only by (i) surrender of this Note to the Maker and the re-issuance of this Note to the transferee, or the Maker’s issuance to the Payee of a new note in the same form as this Note but with the transferee
denoted as the Payee, or (ii) the recording of the identity of the transferee by the Affiliate of the Payee that is maintaining a record ownership register of this Note as agent of, and on behalf of, the Maker. Such Affiliate in its capacity as
such agent shall notify the Maker in writing immediately upon any change in such identity. The terms and conditions of this Note shall be binding upon and inure to the benefit of the Maker and the Payee and their permitted assigns; provided,
however, that if any such assignment (whether by operation of law, by way of transfer or participation, or otherwise) is to any noteholder that is not a “United States person” within the meaning of Section 7701(a)(30) of the Code,
then such noteholder shall submit to the Maker on or before the date of such assignment an IRS Form W-8BEN (or any successor form) certifying as to such noteholder’s status for purposes of determining exemption from United States withholding
tax, information reporting and backup withholding with respect to all payments to be made to such noteholder under the new note (or other instrument). Any attempted transfer in violation of the relevant provisions of this Note shall be void and of
no force and effect. Until there has been a valid transfer of this Note and of all of the rights hereunder by the Payee in accordance with this Note, the Maker shall deem and treat the Payee as the absolute beneficial owner and holder of this Note
and of all of the rights hereunder for all purposes (including, without limitation, for the purpose of receiving all payments to be made under this Note). 
 It is the intention of the Maker and the Payee that this Note is to be a registered instrument and not a bearer instrument and the provisions of this Note are to be interpreted accordingly. This Note is intended to be
registered as to both principal and interest and all payments hereunder shall be made to the named Payee or, in the event of a transfer pursuant to the Facility Agreement and this Note, to the transferee identified in the record of ownership of this
Note maintained by the Payee on behalf of the Maker. Transfer of this Note may not be effected except in accordance with the provisions hereof. 
  

 25 

 IN WITNESS WHEREOF, an authorized representative of the Maker has executed this Note as of the date first
written above. 
  

			
	ARENA PHARMACEUTICALS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

  

 26 

 EXHIBIT C 
 EXISTING INDEBTEDNESS 
 None. 
  

 1 

 EXHIBIT D 
 EXISTING LIENS 
 Lien created by a financing statement filed with the California Secretary of State on June 22,
1999 (as amended by continuations thereof in 2004 and 2009) in favor of Silicon Valley Bank covering substantially all of the assets of the Company. The indebtedness secured by the Lien has been satisfied. The Company has requested that Silicon
Valley Bank file a termination statement with respect to the Lien. 
  

 1Registration Rights Agreement, dated June 17, 2009

 Exhibit 10.2 
 EXECUTION COPY 
 REGISTRATION RIGHTS AGREEMENT 
 REGISTRATION RIGHTS AGREEMENT (this “Agreement”), dated as of June 17, 2009, by and among ARENA PHARMACEUTICALS,
INC., a Delaware corporation (the “Company”), and those lenders set forth on Schedule 1 to the Facility Agreement (as defined below) (each individually, a “Lender” and together, the
“Lenders”). 
 WHEREAS: 
 A. In connection with the Facility Agreement by and among the parties hereto of even date herewith (the “Facility
Agreement”), the Company has agreed, upon the terms and subject to the conditions contained therein, to issue and sell to the Lenders Warrants (as defined in the Facility Agreement) in the amount described in the Facility Agreement,
where each of the Warrants is exercisable for shares of the Company’s common stock, $0.0001 par value per share (the “Common Stock”), each upon the terms and conditions and subject to the limitations and conditions set
forth in the Warrants, all subject to the terms and conditions of the Facility Agreement; and 
 B. To induce the Lenders to execute
and deliver the Facility Agreement, the Company has agreed to provide certain registration rights under the Securities Act of 1933, as amended, and the rules and regulations thereunder, or any similar successor statute (collectively, the
“Securities Act”), and applicable state securities laws. 
 NOW,
THEREFORE, In consideration of the premises and the mutual covenants contained herein and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Company and the
Lenders hereby agree as follows: 
 1. DEFINITIONS. 
 (a) Capitalized terms used but not otherwise defined herein shall have the meanings ascribed to them in the Warrants. 
 (b) As used in this Agreement, the following terms shall have the following meanings: 
 (i)
“Buyer” means each Lender and any permitted transferee or assignee who agrees to become bound by the provisions of this Agreement in accordance with Section 10 hereof. 
 (ii) “Filing Deadline,” for each Registration Statement required to be filed pursuant to Section 2(a)(i) or
Section 2(a)(ii), shall mean a date that is thirty (30) calendar days following the date Warrants are issued pursuant to Section 2.15(a) or Section 2.15(b) of the Facility Agreement, as applicable. 
 (iii) “Global Limit” means the aggregate limits on the number of shares of Common Stock issuable upon exercise of or
otherwise pursuant to the Warrants, as set forth in Section 13(a) of the Warrants. 
  

 1. 

 (iv) “Person” means and includes any natural person, individual,
partnership, joint venture, corporation, trust, limited liability company, limited company, joint stock company, unincorporated organization, government entity or any political subdivision or agency thereof, or any other entity. 
 (v) “Registration Deadline” shall mean the date that is one hundred twenty (120) days after the Filing Deadline.

 (vi) “Register,” “Registered,” and
“Registration” refer to a registration effected by preparing and filing a Registration Statement or Statements in compliance with the Securities Act and pursuant to Rule 415 under the Securities Act or any successor rule
providing for offering securities on a continuous basis, and the declaration or ordering of effectiveness of such Registration Statement by the United States Securities and Exchange Commission (the “SEC”). 
 (vii) “Registrable Securities” means (a) any shares of Common Stock issued or issuable upon Exercise of the Warrants
(without giving effect to any limitations on exercise set forth in the Warrants, other than the Global Limit), including pursuant to a Cash Exercise, a Cashless Exercise or a Cashless Major Exercise, (b) any shares of capital stock issued or
issuable as a dividend or other distribution on or in exchange for or otherwise with respect to any of the foregoing and (c) any securities issued or issuable upon any stock split, recapitalization or similar event with respect to the
foregoing; provided, however, that no such securities shall be deemed Registrable Securities for purposes of this Agreement to the extent that such securities (A) have been sold to the public under a Registration or pursuant to Rule 144
under the Securities Act; (B) have been sold, transferred or otherwise disposed of by a Person in a transaction in which its rights under this Agreement were not validly assigned pursuant to Section 10 hereof or (C) may be immediately
sold to the public without registration or restriction (including without limitation as to volume by each holder thereof) under the Securities Act. 
 (viii) “Registration Statement(s)” means a registration statement(s) of the Company under the Securities Act required to be filed hereunder. 
 (ix) “Trading Day” means any day on which the Common Sock is traded for any period on the NASDAQ Global Market, or on the
principal securities exchange or other securities market on which the Common Stock is then being traded. 
 2. REGISTRATION. 
 (a) MANDATORY REGISTRATION. 
 (i) Following the date on which Warrants are issued pursuant to Section 2.15(a) of the Facility Agreement, the Company shall prepare and, on
or prior to the Filing Deadline, file with the SEC, a Registration Statement on Form S-3 (or, if Form S-3 is not then available, on such other form as is available to effect such a registration) covering the resale of 28,000,000 shares of
Registrable Securities (the “Initial Registration Shares”). 
 (ii) Following the date on which Warrants are
issued pursuant to Section 2.15(b) of the Facility Agreement, the Company shall prepare and, on or prior to the Filing Deadline, file with the SEC, a Registration Statement on Form S-3 (or, if Form S-3 is not then available, on such other form
as is available to effect such a registration) covering the resale of up to 5,600,000 Registrable Securities underlying such Warrants (the “Additional Registration Shares”). 
  

 2. 

 (iii) After filing each Registration Statement pursuant to Section 2(a)(i) or (ii), the
Company shall use commercially reasonable efforts to cause such Registration Statement to become effective under the Securities Act by the Registration Deadline. If for any reason the SEC does not permit all of the Initial Registration Shares or
Additional Registration Shares to be included in the Registration Statement filed pursuant to Section 2(a)(i) or (ii), respectively, then the Company will use commercially reasonable efforts, in consultation with the Staff of the SEC, to as
promptly as practical and as allowable under the Securities Act, cause the registration, under a Registration Statement (an “Additional Registration Statement”) pursuant to Rule 415 under the Securities Act or any successor
rule providing for offering securities on a continuous basis, of the resale of any Initial Registration Shares or Additional Registration Shares that have not been registered under the applicable Registration Statement filed pursuant to
Section 2(a)(i) or (ii). 
 (iv) Each Registration Statement filed pursuant to this Section 2(a), to the extent allowable
under the Securities Act and the rules and regulations promulgated thereunder (including Rule 416), shall state that such Registration Statement also covers such indeterminate number of shares of Common Stock as may be issuable upon exercise of or
otherwise pursuant to the Warrants to prevent dilution resulting from stock splits, stock dividends or similar transactions. The number of shares of Common Stock initially included in each Registration Statement filed pursuant to this
Section 2(a) shall be without regard to any limitation on a Buyer’s ability to exercise the Warrants, other than the Global Limit. Each Registration Statement filed pursuant to this Section 2(a) (and each amendment or supplement
thereto, and each request for acceleration of effectiveness thereof) shall be provided to each Buyer and its counsel prior to its filing or other submission. 
 (b) PIGGY-BACK REGISTRATIONS. If at any time after the date hereof and prior to the expiration of the Registration Period (as hereinafter defined) the Company shall
determine to file with the SEC a Registration Statement relating to an offering for its own account or the account of others under the Securities Act of any of its equity securities (other than on Form S-4 or Form S-8 or their equivalents) (a
“Piggyback Eligible Registration Statement”), the Company shall send to each Buyer written notice of such determination and, if within fifteen (15) days after the effective date of such notice, a Buyer shall so request
in writing, the Company shall include in such Piggyback Eligible Registration Statement all or any part of the Registrable Securities then outstanding that such Buyer requests to be registered, except that if, in connection with any underwritten
public offering for the account of the Company, the managing underwriter(s) thereof shall impose a limitation on the number of Registrable Securities which may be included in the Piggyback Eligible Registration Statement because, in such
underwriter(s)’ judgment, marketing or other factors dictate such limitation is necessary to facilitate public distribution, then the Company shall be obligated to include in such Piggyback Eligible Registration Statement only such limited
portion of the Registrable Securities with respect to which a Buyer has requested inclusion hereunder as the underwriter shall permit; 
  

 3. 

 PROVIDED, HOWEVER, that the Company shall not exclude
any Registrable Securities unless the Company has first excluded all outstanding securities held by holders who are not entitled by contract to the inclusion of such securities in such Piggyback Eligible Registration Statement or are not entitled to
pro rata inclusion with the Registrable Securities (it being understood, for avoidance of doubt, that the Company shall not be required to exclude any securities subject to the Registration Rights Agreement dated December 24, 2003, among the
Company, Mainfield Enterprises, Inc. and Smithfield Fiduciary LLC as amended June 30, 2006, the Settlement Agreement and Release, dated as of June 30, 2006, by and between the Company and Smithfield Fiduciary LLC, and the Exchange
Agreement, dated as of August 14, 2008, between the Company and Mainfield Enterprises, Inc. (collectively, the “Existing Agreements”)); and 
 PROVIDED, FURTHER, HOWEVER, that, after giving effect to the immediately preceding proviso, any exclusion of Registrable Securities shall be made pro
rata with holders of other securities having the contractual right to include such securities in the Piggyback Eligible Registration Statement other than holders of securities entitled to inclusion of their securities in such Piggyback Eligible
Registration Statement by reason of demand registration rights or under the Existing Agreements. No right to registration of Registrable Securities under this Section 2(b) shall be construed to limit any registration required under
Section 2(a) hereof. If an offering in connection with which a Buyer is entitled to registration under this Section 2(b) is an underwritten offering, then a Buyer shall, unless otherwise agreed by the Company, offer and sell such
Registrable Securities in an underwritten offering using the same underwriter or underwriters and, subject to the provisions of this Agreement and the underwriting agreement in such offering, on the same terms and conditions as other shares of
Common Stock included in such underwritten offering (including, without limitation, execution of an agreement with the managing underwriter or agent limiting the sale or distribution such Buyer may make of shares of Common Stock or any securities
convertible or exchangeable or exercisable for such shares of the Company, except as part of such registration). Notwithstanding anything to the contrary set forth herein, the registration rights of the Buyers pursuant to this Section 2(b)
shall only be available to the extent that the Buyer holds outstanding Registrable Securities that are not registered for resale or issuance pursuant to another effective Registration Statement at the time that the Company files a Piggyback Eligible
Registration Statement. 
 3. OBLIGATIONS OF THE COMPANY. In connection with the registration of the Registrable Securities, the Company shall have
the following obligations: 
 (a) The Company shall (i) prepare and file with the SEC the Registration Statement(s) required
pursuant to Section 2(a) above and thereafter use commercially reasonable efforts to cause each such Registration Statement(s) relating to Registrable Securities to become effective as soon as practicable after such filing, and
(ii) subject to Section 3(o) hereof, shall use commercially reasonable efforts to keep each such Registration Statement(s) current and effective pursuant to Rule 415 at all times until such date as the Registrable Securities registered
thereunder cease to be Registrable Securities (the “Registration Period”), which Registration Statement(s) (including any amendments or supplements thereto and prospectuses contained therein), except for information provided
by a Buyer or any transferee of a Buyer pursuant to Section 4(a), shall not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein, or necessary to make the statements therein not
misleading. 
  

 4. 

 (b) Subject to Section 3(o) hereof, the Company shall, during the Registration Period, comply
with the provisions of the Securities Act applicable to the Company with respect to the disposition of all Registrable Securities of the Company covered by each Registration Statement until the earlier of (i) such time as all of such
Registrable Securities have been disposed of in accordance with the intended methods of disposition by the seller or sellers thereof as set forth in each Registration Statement, and (ii) the Registrable Securities registered thereunder cease to
be Registrable Securities. In the event that the number of Registrable Securities issued or issuable pursuant to the Warrants increases above the Initial Registration Shares or Additional Registration Shares, as applicable, (the date of each such
event a “Registration Trigger Date”) such that the number of shares available under the Registration Statements filed pursuant to this Agreement is insufficient to register for resale all of the Registrable Securities issued
or issuable upon exercise of or otherwise pursuant to the Warrants, including, without limitation, any additional shares of Common Stock issuable upon exercise of or otherwise pursuant to the Warrants to prevent dilution resulting from stock splits,
stock dividends or similar transactions, without giving effect to any limitations on the Buyers’ ability to exercise the Warrants (other than the Global Limit), the Company shall use commercially reasonable efforts to amend the Registration
Statements, or file a new Registration Statement (on the short form available therefore, if applicable), or both, so as to register for resale the total number of Registrable Securities so issued or issuable and not covered by Registration
Statements filed pursuant to this Agreement, as of the applicable Registration Trigger Date, as soon as practicable after the Registration Trigger Date (with the number of additional Registrable Securities based on the Exercise Price of the
Warrants, if applicable, and other relevant factors on which the Company reasonably elects to rely). The Company shall use commercially reasonable efforts to cause such amendment and/or new Registration Statement to become effective as soon as
practicable following the filing thereof. 
 (c) The Company shall furnish or otherwise make available to each Buyer and its legal
counsel (i) promptly after the same is prepared and publicly distributed, filed with the SEC, or received by the Company, one copy of each Registration Statement and any amendment thereto, each preliminary prospectus and prospectus and each
amendment or supplement thereto, and, in the case of a Registration Statement referred to in Section 2(a), each letter written by or on behalf of the Company to the SEC or the staff of the SEC, and each item of correspondence from the SEC or
the staff of the SEC, in each case relating to such Registration Statement (other than any portion of any thereof which contains material non-public information or information for which the Company has sought or intends to seek confidential
treatment), and (ii) such number of copies of a prospectus, including a preliminary prospectus, and all amendments and supplements thereto and such other documents as a Buyer may reasonably request in order to facilitate the disposition of the
Registrable Securities owned by a Buyer. The Company will promptly notify each Buyer by facsimile or email of the effectiveness of each Registration Statement or any post-effective amendment. The Company will promptly respond to any and all comments
received from the SEC, with a view towards causing each Registration Statement or any amendment thereto to be declared effective by the SEC as soon as practicable and shall file an acceleration request as soon as practicable, but no later than five
(5) business days, following the later of (i) resolution or clearance of all SEC comments or, if applicable, notification by the SEC that any such Registration Statement or any amendment thereto will not be subject to review and
(ii) the date the Company is notified in writing of any comments (or that there are no comments), to the Company’s request for acceleration, from the single firm designated by the Buyers to review such acceleration request pursuant to
Section 3(g). 
  

 5. 

 (d) The Company shall use commercially reasonable efforts to (i) register and qualify, in any
jurisdiction where registration and/or qualification is required, the Registrable Securities covered by the Registration Statements under such other securities or “blue sky” laws of such jurisdictions in the United States as a Buyer shall
reasonably request in writing, (ii) prepare and file in those jurisdictions such amendments (including post-effective amendments) and supplements to such registrations and qualifications as may be necessary to maintain the effectiveness thereof
during the Registration Period, (iii) take such other actions as may be necessary to maintain such registrations and qualifications in effect at all times during the Registration Period, and (iv) take all other actions reasonably necessary
or advisable to qualify the Registrable Securities for sale in such jurisdictions, provided, however, that the Company shall not be required in connection therewith or as a condition thereto to (A) qualify to do business in any
jurisdiction where it would not otherwise be required to qualify but for this Section 3(d), (B) subject itself to general taxation in any such jurisdiction, or (C) file a general consent to service of process in any such jurisdiction.

 (e) Subject to Section 3(o) hereof, as promptly as practicable after becoming aware of such event, the Company shall notify
each Buyer who holds Registrable Securities of the happening of any event, of which the Company has knowledge, as a result of which the prospectus included in any Registration Statement, as then in effect, includes an untrue statement of a material
fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading, and use its commercially reasonable efforts promptly to prepare a supplement or amendment to any Registration Statement
to correct such untrue statement or omission, and deliver such number of copies of such supplement or amendment to each Buyer as such Buyer may reasonably request. 
 (f) The Company shall use commercially reasonable efforts to prevent the issuance of any stop order or other suspension of effectiveness of any Registration Statement, and, if such an order is issued, to obtain
the withdrawal of such order at the earliest practical moment and to notify each Buyer who holds Registrable Securities being sold (or, in the event of an underwritten offering, the managing underwriters) of the issuance of such order and the
resolution thereof. 
 (g) The Company shall permit a single firm of counsel designated by the Buyers to review such Registration
Statement and all amendments and supplements thereto (as well as all requests for acceleration or effectiveness thereof), at Buyers’ own cost, a reasonable period of time prior to their filing with the SEC (not less than five (5) business
days) and use commercially reasonable efforts to reflect in such documents any comments as such counsel may reasonably propose (so long as such comments are provided to the Company at least (2) business days prior to the expected filing date)
and will not request acceleration of such Registration Statement without prior notice to such counsel; provided that the Company shall make the final decision as to the form and content of each such document. 
 (h) The Company shall use commercially reasonable efforts to cause all the Registrable Securities covered by each Registration Statement to be
listed on each securities exchange on which securities of the same class or series issued by the Company are then listed, if any, if the listing of such Registrable Securities is then permitted under the rules of such exchange. 
  

 6. 

 (i) The Company shall provide a transfer agent and registrar, which may be a single entity, for
the Registrable Securities not later than the effective date of the Initial Registration Statement. 
 (j) The Company shall cooperate
with each Buyer who holds Registrable Securities being offered and the managing underwriter or underwriters as reasonably requested by them with respect to an applicable Registration Statement, if any, to facilitate the timely preparation and
delivery of certificates (not bearing any restrictive legends) representing Registrable Securities sold pursuant to such Registration Statement and enable such certificates to be in such denominations or amounts, as the case may be, as the managing
underwriter or underwriters, if any, or a Buyer may reasonably request and registered in such names as the managing underwriter or underwriters, if any, or a Buyer may request, and, within ten (10) business days after a Registration Statement
which includes Registrable Securities is ordered effective by the SEC, the Company shall deliver, and shall cause legal counsel selected by the Company to deliver, to the transfer agent for the Registrable Securities (with copies to each Buyer) an
appropriate instruction and an opinion of such counsel in the form required by the transfer agent in order to issue such Registrable Securities free of restrictive legends upon the resale of such Registrable Securities pursuant to such Registration
Statement. 
 (k) At the reasonable request of a Buyer, the Company shall prepare and file with the SEC such amendments (including
post-effective amendments) and supplements to a Registration Statement and any prospectus used in connection with the Registration Statement as may be necessary in order to make reasonable changes to the plan of distribution set forth in such
Registration Statement. 
 (l) The Company shall not, and shall not agree to, allow the holders of any securities of the Company,
other than holders of the Registrable Securities and holders of securities pursuant to the Existing Agreements, to include any of their securities in any Registration Statement under Section 2(a) hereof or any amendment or supplement thereto
under Section 3(a) hereof without the consent of the Buyers. In addition, the Company shall not offer any securities for its own account or the account of others in any Registration Statement under Section 2(a) hereof or any amendment or
supplement thereto under Section 3(a) hereof without the consent of the Buyers. 
 (m) The Company shall use commercially
reasonable efforts to comply with all applicable laws related to a Registration Statement and offering and sale of securities and all applicable rules and regulations of governmental authorities in connection therewith (including without limitation
the Securities Act and the Exchange Act and the rules and regulations promulgated by the SEC). 
 (n) If required by the Financial
Industry Regulatory Authority, Inc. (“FINRA”) Corporate Financing Department, the Company shall promptly effect a filing with the FINRA pursuant to FINRA Rule 5110 with respect to the public offering contemplated by 

  

 7. 

 
resales of securities under the Registration Statement (an “Issuer Filing”), and pay the filing fee required by such Issuer Filing.
The Company shall use commercially reasonable efforts to pursue the Issuer Filing until the FINRA issues a letter confirming that it does not object to the terms of the offering contemplated by the Registration Statement. 
 (o) Notwithstanding anything to the contrary herein, at any time after the Registration Statement has been declared effective by the SEC, the
Company may delay or suspend the effectiveness of any Registration Statement or the use of any prospectus forming a part of the Registration Statement, in its sole discretion, due to the non-disclosure of material, non-public information concerning
the Company, the disclosure of which at the time is not in its best interest, in the good faith opinion of the Company (a “Grace Period”); provided, that the Company shall promptly notify each Buyer in writing of the
existence of a Grace Period in conformity with the provisions of this Section 3(o) and the date on which the Grace Period will begin (such notice, a “Commencement Notice”); and, provided further, that no Grace Period
shall exceed forty-five (45) days, and such Grace Periods shall not exceed an aggregate total of ninety (90) days during any 12-month period. For purposes of determining the length of a Grace Period above, the Grace Period shall begin on
and include the date specified by the Company in the Commencement Notice and shall end on and include the date each Buyer receives written notice of the termination of the Grace Period by the Company (which notice may be contained in the
Commencement Notice). The provisions of Sections 3(a)(ii), 3(b) and 3(e) hereof shall not be applicable during any Grace Period. Upon expiration of the Grace Period, the Company shall again be bound by Sections 3(a)(ii), 3(b) and 3(e) with respect
to the information giving rise thereto unless such material, non-public information is no longer applicable. 
 (p) Notwithstanding
anything to the contrary herein, a delay in the effectiveness of any Registration Statement caused solely by the filing of a request for confidential treatment shall not be deemed a breach of the Company’s obligations set forth herein and in
the case of each Registration Statement required to be filed pursuant to Section 2(a)(i) or Section 2(a)(ii), the Registration Deadline shall be deemed extended to the date that is ten (10) business days after the date the SEC agrees
to allow confidential treatment pursuant to such request or the date such request is withdrawn by the Company, as applicable. 
 4. OBLIGATIONS OF THE
BUYER. In connection with the registration of the Registrable Securities, each Buyer shall have the following obligations: 
 (a)
It shall be a condition precedent to the obligations of the Company to complete a Registration pursuant to this Agreement with respect to the Registrable Securities of a Buyer that such Buyer shall furnish to the Company such information
regarding itself, the Registrable Securities held by it and the intended method of disposition of the Registrable Securities held by it as shall be reasonably required to effect the registration of such Registrable Securities and shall execute such
documents in connection with such registration as the Company may reasonably request. At least five (5) business days prior to the first anticipated filing date of a Registration Statement under which Registrable Securities will be registered,
the Company shall notify each Buyer of the information the Company requires from such Buyer. Any such information shall not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein, or necessary
to make the statements therein not misleading. A Buyer must provide such information to the Company at least two (2) business days prior to the first anticipated filing date of such Registration Statement if such Buyer elects to have any
Registrable Securities included in the Registration Statement. 
  

 8. 

 (b) Each Buyer, by the Buyer’s acceptance of the Registrable Securities, agrees to cooperate
with the Company as reasonably requested by the Company in connection with the preparation and filing of each Registration Statement hereunder, unless the Buyer has notified the Company in writing of the Buyer’s election to exclude all of the
Buyer’s Registrable Securities from such Registration Statement. 
 (c) In the event of an underwritten offering pursuant to
Section 2(b) in which any Registrable Securities are to be included, each Buyer agrees to enter into and perform such Buyer’s obligations under an underwriting agreement, in usual and customary form, including, without limitation,
customary indemnification and contribution obligations, with the managing underwriter of such offering and take such other actions as are reasonably required in order to expedite or facilitate the disposition of the Registrable Securities, unless
the Buyer has notified the Company in writing of the Buyer’s election to exclude all of the Buyer’s Registrable Securities from such Registration Statement. 
 (d) Each Buyer agrees that, upon receipt of any notice from the Company of the happening of any event of the kind described in Sections 3(e), 3(f) or 3(o), the Buyer will immediately discontinue disposition of
Registrable Securities pursuant to the Registration Statement covering such Registrable Securities until the Buyer’s receipt of the copies of the supplemented or amended prospectus contemplated by Section 3(e) or 3(f) or notice from the
Company of the termination of the Grace Period, and, if so directed by the Company, the Buyer shall deliver to the Company (at the expense of the Company) or destroy (and deliver to the Company a certificate of destruction) all copies in the
Buyer’s possession, of the prospectus covering such Registrable Securities current at the time of receipt of such notice. 
 (e)
Each Buyer agrees that it will not effect any disposition or other transfer of the Registrable Securities that would constitute a sale within the meaning of the Securities Act other than transactions exempt from the registration requirements of
the Securities Act or pursuant to, and as contemplated in, a Registration Statement, and that it will promptly notify the Company of any material changes in the information set forth in a Registration Statement furnished by or regarding such Buyer
or its plan of distribution other than changes in the number of shares beneficially owned. 
 5. REMEDIES. In the event of a breach by the Company of
its obligations under this Agreement, each Buyer, in addition to being entitled to exercise all rights granted by law, including recovery of damages, will be entitled to specific performance of its rights under this Agreement. 
 6. EXPENSES OF REGISTRATION. All expenses of the Company incurred in connection with registrations, filings or qualifications pursuant to Sections 2 and 3,
including, without limitation, all registration, listing and qualification fees, printers and accounting fees and the fees and disbursements of counsel for the Company, shall be borne by the Company. All expenses of the Buyers incurred in connection
with registrations, filings or qualifications pursuant to Sections 2 and 3, including, without limitation, underwriting discounts and commissions and legal expenses incurred by any Buyer for review of any Registration Statement, shall be borne by
the applicable Buyer. 
  

 9. 

 7. INDEMNIFICATION. In the event any Registrable Securities are included in a Registration Statement under this
Agreement: 
 (a) The Company will indemnify, hold harmless and defend (i) each Buyer, (ii) the directors, officers,
partners, managers, members, employees, agents and each person who controls each Buyer within the meaning of the Securities Act or the Exchange Act, if any, (iii) any underwriter (as defined in the Securities Act) for each Buyer in connection
with an underwritten offering pursuant to Section 2(b) hereof, and (iv) the directors, officers, partners, managers, members, employees, agents and each person who controls any such underwriter within the meaning of the Securities Act or
the Exchange Act, if any (each, an “Indemnified Person”), against any joint or several losses, claims, damages, liabilities or expenses (collectively, together with actions, proceedings or inquiries by any regulatory or
self-regulatory organization, whether commenced or threatened, in respect thereof, “Claims”) to which any of them may become subject insofar as such Claims arise out of or are based upon: (i) any untrue statement or
alleged untrue statement of a material fact in a Registration Statement or the omission or alleged omission to state therein a material fact required to be stated or necessary to make the statements therein not misleading; (ii) any untrue
statement or alleged untrue statement of a material fact contained in any preliminary prospectus if used prior to the effective date of such Registration Statement, or contained in the final prospectus (as amended or supplemented, if the Company
files any amendment thereof or supplement thereto with the SEC) or the omission or alleged omission to state therein any material fact necessary to make the statements made therein, in light of the circumstances under which the statements therein
were made, not misleading; or (iii) any violation or alleged violation by the Company of the Securities Act, the Exchange Act, any other law, including, without limitation, any state securities law, or any rule or regulation thereunder, in each
case relating to the offer or sale of the Registrable Securities (the matters in the foregoing clauses (i) through (iii) being, collectively, “Violations”). The Company shall reimburse the Indemnified Person,
promptly as such expenses are incurred and are due and payable, for any reasonable legal fees or other reasonable expenses incurred by them in connection with investigating or defending any such Claim. Notwithstanding anything to the contrary
contained herein, the indemnification agreement contained in this Section 7(a): (A) shall not apply to a Claim arising out of or based upon a Violation to the extent that such Violation occurs in reliance upon and in conformity with
information furnished in writing to the Company by any Indemnified Person for use in connection with the preparation of such Registration Statement or any such amendment thereof or supplement thereto; (B) with respect to any preliminary
prospectus, shall not inure to the benefit of any such Person from whom the Person asserting any such Claim purchased the Registrable Securities that are the subject thereof (or to the benefit of any Person controlling such Person) if the untrue
statement or omission of material fact contained in the preliminary prospectus was corrected in the prospectus, as then amended or supplemented, if such prospectus was timely made available by the Company pursuant to Section 3(c), and the
Indemnified Person was promptly advised in writing not to use the incorrect prospectus prior to the use giving rise to a Violation; (C) shall not be available to the extent such Claim is based on a failure of the Indemnified Person to deliver
or to cause to be delivered the prospectus made available by the Company, including a corrected prospectus, if such prospectus or corrected prospectus was timely made available by the Company pursuant to Section 3(e); and (D) shall not
apply to amounts paid in settlement of any Claim if 

  

 10. 

 
such settlement is effected without the prior written consent of the Company. Such indemnity shall remain in full force and effect regardless of any
investigation made by or on behalf of the Indemnified Person and shall survive the transfer of the Registrable Securities by a Buyer pursuant to Section 10 and shall be binding on any transferee. 
 (b) Promptly after receipt by an Indemnified Person under this Section 7 of notice of the commencement of any action (including any
governmental action), such Indemnified Person shall, if a Claim in respect thereof is to be made against the Company under this Section 7, deliver to the Company a written notice of the commencement thereof, and the Company shall have the right
to participate in, and, to the extent the Company so desires, to assume control of the defense thereof with counsel mutually satisfactory to the Company and the Indemnified Person, as the case may be. 
 PROVIDED, HOWEVER, that an Indemnified Person shall have the right to retain its own counsel with the
reasonable fees and expenses to be paid by the Company, if, in the reasonable opinion of counsel for a Buyer, the representation by such counsel of the Indemnified Person and the Company would be inappropriate due to actual or potential material
differing interests between such Indemnified Person and any other party represented by such counsel in such proceeding. The Company shall pay for only one separate legal counsel for the Indemnified Persons, and such legal counsel shall be selected
by the Buyers. The failure to deliver written notice to the Company within a reasonable time of the commencement of any such action shall not relieve the Company of any liability to the Indemnified Person under this Section 7, except to the
extent that the Company is actually prejudiced in its ability to defend such action. The indemnification required by this Section 7 shall be made by periodic payments of the amount thereof during the course of the investigation or defense, as
such expense, loss, damage or liability is incurred and is due and payable. 
 (c) Each Buyer will indemnify, hold harmless and defend
(i) the Company, and (ii) the directors, officers, partners, managers, members, employees, agents and each person who controls the Company within the meaning of the Securities Act or the Exchange Act, if any (each, a “Company
Indemnified Person”), against any joint or several losses, claims, damages, liabilities or expenses (collectively, together with actions, proceedings or inquiries by any regulatory or self-regulatory organization, whether commenced or
threatened, in respect thereof, “Indemnity Claims”) to which any of them may become subject insofar as such Indemnity Claims arise out of or are based upon any Violation which occurs due to the inclusion by the Company in a
Registration Statement of false or misleading information about such Buyer, where such information was furnished in writing to the Company by such Buyer expressly for inclusion in such Registration Statement. Such Buyer shall reimburse the Company
Indemnified Person, promptly as such expenses are incurred and are due and payable, for any reasonable legal fees or other reasonable expenses incurred by them in connection with investigating or defending any such Claim, provided, however, that the
indemnity agreement contained in this Section 7(c) and the agreement with respect to contribution contained in Section 8 shall not apply to amounts paid in settlement of any Claim if such settlement is effected without the prior written
consent of the Buyer and which consent shall not be unreasonably withheld or delayed; provided, further, however, that the Buyer shall be liable under this Section 7(c) for only that amount of a Claim as does not exceed the net amount of
proceeds received by the Buyer as a result of the sale of Registrable Securities pursuant to such 

  

 11. 

 
Registration Statement. Such indemnity shall remain in full force and effect regardless of any investigation made by or on behalf of the Company Indemnified
Person. Notwithstanding anything to the contrary contained herein, the indemnification agreement contained in this Section 7(c) with respect to any preliminary prospectus shall not inure to the benefit of any Company Indemnified Person if the
untrue statement or omission of material fact contained in the preliminary prospectus was corrected on a timely basis in the prospectus, as then amended or supplemented. 
 (d) Promptly after receipt by a Company Indemnified Person under this Section 7 of notice of the commencement of any action (including any governmental action), such Company Indemnified Person shall, if a
Claim in respect thereof is to be made against a Buyer under this Section 7, deliver to such Buyer a written notice of the commencement thereof, and such Buyer shall have the right to participate in, and, to the extent the Buyer so desires, to
assume control of the defense thereof with counsel mutually satisfactory to the Buyer and the Company Indemnified Person, as the case may be. 
 PROVIDED, HOWEVER, that a Company Indemnified Person shall have the right to retain its own counsel with the reasonable fees and expenses to be paid by the applicable Buyer, if, in the
reasonable opinion of counsel for the Company, the representation by such counsel of the Company Indemnified Person and such Buyer would be inappropriate due to actual or potential material differing interests between such Company Indemnified Person
and any other party represented by such counsel in such proceeding. A Buyer shall pay for only one separate legal counsel for the Company Indemnified Persons, and such legal counsel shall be selected by Company. The failure to deliver written notice
to a Buyer within a reasonable time of the commencement of any such action shall not relieve the Buyer of any liability to the Company Indemnified Person under this Section 7, except to the extent that the Buyer is actually prejudiced in its
ability to defend such action. The indemnification required by this Section 7 shall be made by periodic payments of the amount thereof during the course of the investigation or defense, as such expense, loss, damage or liability is incurred and
is due and payable. 
 8. CONTRIBUTION. To the extent any indemnification by the Company or a Buyer is prohibited or limited by law, each of the
Company and each Buyer agrees to make the maximum contribution with respect to any amounts for which it would otherwise be liable under Section 7 to the fullest extent permitted by law, based upon a comparative fault standard, that (i) no
Person that is guilty of fraudulent misrepresentation (within the meaning Section 11(f) of the Securities Act) in connection with such sale shall be entitled to contribution from any Person who was not guilty of fraudulent misrepresentation;
and (ii) contribution by a Buyer shall be limited in amount to the net amount of proceeds received by the Buyer from the sale of such Registrable Securities pursuant to a Registration Statement. 
 9. REPORTS UNDER THE 1934 ACT. With a view to making available to the Buyers the benefits of Rule 144 promulgated under the Securities Act or any other
similar rule or regulation of the SEC that may at any time permit the Buyers to sell securities of the Company to the public without registration, the Company agrees to: 
 (a) make and keep public information available, as those terms are understood and defined in Rule 144; 
  

 12. 

 (b) file with the SEC in a timely manner all reports and other documents required of the Company
under the Securities Act and the Exchange Act so long as the Company remains subject to such requirements and the filing of such reports and other documents is required for the applicable provisions of Rule 144; and 
 (c) furnish to the Buyers, so long as the Buyers own Registrable Securities, promptly upon request, (i) a written statement by the Company
that it has complied with the reporting requirements of the Securities Act and the Exchange Act as required for applicable provisions of Rule 144, (ii) a copy of the most recent annual or quarterly report of the Company and such other reports
and documents so filed by the Company, and (iii) such other information as may be reasonably requested to permit the Buyers to sell such securities pursuant to Rule 144 without registration. 
 Each Buyer shall at all times comply with the restrictions on transfer contained in Section 8 of the Warrant, which provisions are hereby
incorporated by reference and made a part hereof. 
 10. ASSIGNMENT OF REGISTRATION RIGHTS. The rights under this Agreement shall be automatically
assignable by each Buyer to any transferee of all or any portion of such Buyer’s Registrable Securities (provided such transfer is permitted under the applicable Warrant) if: (i) the Buyer agrees in writing with the transferee or assignee
to assign such rights, and a copy of such agreement is furnished to the Company within a reasonable time after such assignment, (ii) the Company is, within a reasonable time after such transfer or assignment, furnished with written notice of
(a) the name and address of such transferee or assignee, and (b) the securities with respect to which such registration rights are being transferred or assigned, and (iii) at or before the time the Company receives the written notice
contemplated by clause (ii) of this sentence, the transferee or assignee agrees in writing with the Company to be bound by all of the provisions contained herein. In the event that a Buyer transfers all or any portion of its Registrable
Securities pursuant to this Section, the Company shall have at least ten (10) Trading Days following the receipt of such notice to file any amendments or supplements necessary to keep a Registration Statement current and effective pursuant to
Rule 415. 
 11. AMENDMENT OF REGISTRATION RIGHTS. Provisions of this Agreement may be amended and the observance thereof may be waived (either
generally or in a particular instance and either retroactively or prospectively), only with written consent of the Company and the holders of a majority in interest of then-outstanding Registrable Securities. Any amendment or waiver effected in
accordance with this Section 11 shall be binding upon each of the Buyers and the Company. 
 12. TERMINATION OF RIGHTS AND OBLIGATIONS. The
obligations of the Company pursuant to the terms of this Agreement, other than the obligations set forth in Sections 6, 7, 8 and 13, shall terminate upon the date upon which all Registrable Securities held by a Buyer or issuable upon
exercise of Warrants cease to be Registrable Securities. 
  

 13. 

 13. MISCELLANEOUS. 
 (a) A person or entity is deemed to be a holder of Registrable Securities whenever such person or entity owns of record or beneficially through a “street name” holder such Registrable Securities. If
the Company receives conflicting instructions, notices or elections from two or more persons or entities with respect to the same Registrable Securities, the Company shall act upon the basis of instructions, notice or election received from the
registered owner of such Registrable Securities. 
 (b) Any notices required or permitted to be given under the terms hereof shall be
in writing and shall be deemed given only if sent by certified or registered mail (return receipt requested) or delivered personally or by courier (including a recognized overnight delivery service) or by facsimile and shall be effective five days
after being placed in the mail, if mailed by regular United States mail, or upon receipt, if delivered personally or by courier (including a recognized overnight delivery service) or by facsimile, in each case addressed to a party. The addresses for
such communications shall be: 
 If to the Company: 
 Arena Pharmaceuticals, Inc. 
 6166 Nancy Ridge Drive 
 San Diego, CA 92121 
 Fax: (858) 677-0065

 Attn: General Counsel 
 With
copy to: 
 Cooley Godward Kronish LLP 
 4401 Eastgate Mall 
 San Diego, CA 92121 
 Fax: (858) 550-6420 
 Attn: Steven M. Przesmicki, Esq. 
 If to a Buyer: 
 c/o Deerfield Capital, L.P.

 780 Third Avenue, 37th Floor 
 New York, New
York 10017 
 Fax: (212) 599-1248 
 Attn: Alexander Karnal 
 With a copy to: 
 Katten Muchin Rosenman LLP 
 575 Madison Avenue 
 New York, New York 10022 
 Fax:
(212) 940-8776 
 Attn: Mark I. Fisher, Esq. 
 Elliot Press, Esq. 
  

 14. 

 Each party shall provide notice to the other party of any change in address. 
 (c) Failure of any party to exercise any right or remedy under this Agreement or otherwise, or delay by a party in exercising such right or
remedy, shall not operate as a waiver thereof. 
 (d) GOVERNING LAW. All
questions concerning the construction, validity, enforcement and interpretation of this Agreement shall be governed by and construed and enforced in accordance with the internal laws of the State of New York, without regard to the principles of
conflicts of law thereof. Each party agrees that all legal proceedings concerning the interpretations, enforcement and defense of the transactions contemplated by this Agreement (whether brought against a party hereto or its respective affiliates,
directors, officers, shareholders, employees or agents) shall be commenced exclusively in either the state and federal courts sitting in the City of New York or City of San Diego, California. Each party hereby irrevocably submits to the exclusive
jurisdiction of the state and federal courts sitting in the City of New York, borough of Manhattan and the City of San Diego, California for the adjudication of any dispute hereunder or in connection herewith or with any transaction contemplated
hereby or discussed herein, and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding, any claim that it is not personally subject to the jurisdiction of any such court, that such suit, action or proceeding is
improper or is an inconvenient venue for such proceeding. Each party hereby irrevocably waives personal service of process and consents to process being served in any such suit, action or proceeding by mailing a copy thereof via registered or
certified mail or overnight delivery (with evidence of delivery) to such party at the address in effect for notices to it under this Agreement and agrees that such service shall constitute good and sufficient service of process and notice thereof.
Nothing contained herein shall be deemed to limit in any way any right to serve process in any other manner permitted by law. The parties hereby waive all rights to a trial by jury. If either party shall commence an action or proceeding to enforce
any provision of this Agreement, then the prevailing party in such action or proceeding shall be reimbursed by the other party for its reasonable attorneys’ fees and other costs and expenses incurred with the investigation, preparation and
prosecution of such action or proceeding. 
 (e) This Agreement, the Warrants and the Facility Agreement (including all schedules and
exhibits thereto) constitute the entire agreement among the parties hereto with respect to the subject matter hereof and thereof. There are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein and
therein. This Agreement, the Warrants and the Facility Agreement supersede all prior agreements and understandings among the parties hereto with respect to the subject matter hereof and thereof. 
 (f) Subject to the requirements of Section 10 hereof, this Agreement shall inure to the benefit of and be binding upon the successors and
assigns of each of the parties hereto. 
 (g) The headings in this Agreement are for convenience of reference only and shall not limit
or otherwise affect the meaning hereof. 
  

 15. 

 (h) This Agreement may be executed in two or more counterparts, each of which shall be deemed an
original but all of which shall constitute one and the same agreement. This Agreement, once executed by a party, may be delivered to the other party hereto by facsimile transmission of a copy of this Agreement bearing the signature of the party so
delivering this Agreement, which facsimile transmission shall be deemed an original thereof. 
 (i) Each party shall do and perform,
or cause to be done and performed, all such further acts and things, and shall execute and deliver all such other agreements, certificates, instruments and documents, as the other party may reasonably request in order to carry out the intent and
accomplish the purposes of this Agreement and the consummation of the transactions contemplated hereby. 
 (j) The Company
acknowledges that a breach by it of its obligations hereunder will cause irreparable harm to the Buyers by vitiating the intent and purpose of the transactions contemplated hereby. Accordingly, the Company acknowledges that the remedy at law for
breach of its obligations hereunder will be inadequate and agrees, in the event of a breach or threatened breach by the Company of any of the provisions hereunder, that the Buyers shall be entitled, in addition to all other available remedies in law
or in equity, to an injunction or injunctions to prevent or cure breaches of the provisions of this Agreement and to enforce specifically the terms and provisions hereof, without the necessity of showing economic loss and without any bond or other
security being required. 
 (k) The language used in this Agreement will be deemed to be the language chosen by the parties to express
their mutual intent, and no rules of strict construction will be applied against any party. 
 (l) In the event that any provision of
this Agreement is invalid or unenforceable under any applicable statute or rule of law, then such provision shall be deemed inoperative to the extent that it may conflict therewith and shall be deemed modified to conform with such statute or rule of
law. Any provision hereof which may prove invalid or unenforceable under any law shall not affect the validity or enforceability of any other provision hereof. 
 (m) In the event a Buyer shall sell or otherwise transfer any of such holder’s Registrable Securities, each transferee shall be allocated a pro rata portion of the number of Registrable Securities included
in a Registration Statement for such transferor. 
 (n) There shall be no oral modifications or amendments to this Agreement. This
Agreement may be modified or amended only in writing. 
 [Remainder of page left intentionally blank] 
 [Signature page follows] 
  

 16. 

 EXECUTION COPY 
 IN WITNESS WHEREOF, the undersigned Buyers and the Company have caused this Registration Rights Agreement to be duly executed as of
the 17th day of June, 2009. 
  

									
	COMPANY:	  	 	  	BUYERS:
			
	ARENA PHARMACEUTICALS, INC.	  		  	DEERFIELD PRIVATE DESIGN FUND, L.P.
					
	By:	  	 /s/    Jack Lief
	  		  	By:	  	 /s/    James E. Flynn

	Name:	  	Jack Lief	  		  	Name:	  	James E. Flynn
	Title:	  	President and Chief Executive Officer	  		  	Title:	  	General Partner
				
		  		  		  	 DEERFIELD PRIVATE DESIGN
 INTERNATIONAL, L.P.

					
		  		  		  	By:	  	 /s/    James E. Flynn

		  		  		  	Name:	  	James E. Flynn
		  		  		  	Title:	  	General Partner
				
		  		  		  	DEERFIELD PARTNERS, L.P.
					
		  		  		  	By:	  	 /s/    James E. Flynn

		  		  		  	Name:	  	James E. Flynn
		  		  		  	Title:	  	General Partner
				
		  		  		  	DEERFIELD INTERNATIONAL LIMITED
					
		  		  		  	By:	  	 /s/    James E. Flynn

		  		  		  	Name:	  	James E. Flynn
		  		  		  	Title:	  	Director
				
		  		  		  	DEERFIELD SPECIAL SITUATIONS FUND, L.P.
					
		  		  		  	By:	  	 /s/    James E. Flynn

		  		  		  	Name:	  	James E. Flynn
		  		  		  	Title:	  	General Partner
				
		  		  		  	 DEERFIELD SPECIAL SITUATIONS FUND
 INTERNATIONAL LIMITED

					
		  		  		  	By:	  	 /s/    James E. Flynn

		  		  		  	Name:	  	James E. Flynn
		  		  		  	Title:	  	Director

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