Onyx Pharmaceuticals, Inc. 4.00% Convertible Senior Notes Due 2016 Underwriting Agreement

Exhibit 1.2

Onyx Pharmaceuticals, Inc.

4.00% Convertible Senior Notes Due 2016

Underwriting Agreement

August 6, 2009

Xxxxxxx, Xxxxx & Co.

As representative of the several Underwriters
named in Schedule I hereto,

00 Xxxxx Xxxxxx,
Xxx Xxxx, Xxx Xxxx 00000.

Ladies and Gentlemen:

Onyx Pharmaceuticals, Inc., a Delaware corporation (the “Company”), proposes, subject to the terms and conditions stated herein, to issue and sell to the Underwriters named in Schedule I hereto (the “Underwriters”) an aggregate of $200,000,000 principal amount of the 4.00% Convertible Senior Notes due 2016 (the “Firm Securities”), convertible into shares of common stock of the Company, par value $0.001 per share (“Stock”), and, at the election of the Underwriters, up to an aggregate of $30,000,000 additional principal amount of 4.00% Convertible Senior Notes due 2016 (the “Optional Securities) (the Firm Securities and the Optional Securities that the Underwriters elect to purchase pursuant to Section 2 hereof are herein collectively called the “Securities”).

1. The Company represents and warrants to, and agrees with, each of the Underwriters that:

(a) An “automatic shelf registration statement” as defined under Rule 405 under the Securities Act of 1933, as amended (the “Act”) on Form S-3 (File No. 333-143825) in respect of the Securities and shares of Stock issuable upon conversion thereof has been filed with the Securities and Exchange Commission (the “Commission”) not earlier than three years prior to the date hereof; such registration statement, and any post-effective amendment thereto, became effective on filing; and no stop order suspending the effectiveness of such registration statement or any part thereof has been issued and no proceeding for that purpose has been initiated or threatened by the Commission, and no notice of objection of the Commission to the use of such registration statement or any post-effective amendment thereto pursuant to Rule 401(g)(2) under the Act has

been received by the Company (the base prospectus filed as part of such registration statement, in the form in which it has most recently been filed with the Commission on or prior to the date of this Agreement, is hereinafter called the “Basic Prospectus”; any preliminary prospectus (including any preliminary prospectus supplement) relating to the Securities filed with the Commission pursuant to Rule 424(b) under the Act is hereinafter called a “Preliminary Prospectus”; the various parts of such registration statement, including all exhibits thereto but excluding Form T-1 and including any prospectus supplement relating to the Securities that is filed with the Commission and deemed by virtue of Rule 430B to be part of such registration statement, each as amended at the time such part of the registration statement became effective, are hereinafter collectively called the “Registration Statement”; the Basic Prospectus, as amended and supplemented immediately prior to the Applicable Time (as defined in Section 1(c) hereof), is hereinafter called the “Pricing Prospectus”; the form of the final prospectus relating to the Securities filed with the Commission pursuant to Rule 424(b) under the Act in accordance with Section 5(a) hereof is hereinafter called the “Prospectus”; any reference herein to the Basic Prospectus, the Pricing Prospectus, any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include the documents incorporated by reference therein pursuant to Item 12 of Form S-3 under the Act, as of the date of such prospectus; any reference to any amendment or supplement to the Basic Prospectus, any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include any post-effective amendment to the Registration Statement, any prospectus supplement relating to the Securities filed with the Commission pursuant to Rule 424(b) under the Act and any documents filed under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and incorporated therein, in each case after the date of the Basic Prospectus, such Preliminary Prospectus, or the Prospectus, as the case may be; any reference to any amendment to the Registration Statement shall be deemed to refer to and include any annual report of the Company filed pursuant to Section 13(a) or 15(d) of the Exchange Act after the effective date of the Registration Statement that is incorporated by reference in the Registration Statement; and any “issuer free writing prospectus” as defined in Rule 433 under the Act relating to the Securities and listed on Schedule II(a) hereto is hereinafter called an “Issuer Free Writing Prospectus”);

(b) No order preventing or suspending the use of any Preliminary Prospectus or any Issuer Free Writing Prospectus has been issued by the Commission, and each Preliminary Prospectus, at the time of filing thereof, conformed in all material respects to the requirements of the Act and the rules and regulations of the Commission thereunder, and did not contain an 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, in the light of the circumstances under which they were made, not misleading; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through Xxxxxxx, Sachs & Co. expressly for use therein;

(c) For the purposes of this Agreement, the “Applicable Time” is 8:30 P.M. (Eastern time) on the date of this Agreement; the Pricing Prospectus as supplemented by the final term sheet prepared and filed pursuant to Section 5(a) hereof, taken together (collectively, the “Pricing Disclosure Package”) as of the Applicable Time, did not include any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; and each Issuer Free Writing Prospectus listed on Schedule II(a) hereto does not conflict with the information contained in the Registration Statement, the Pricing Prospectus or the Prospectus and each such Issuer Free Writing Prospectus, as supplemented by and taken together with the Pricing Disclosure Package as of the Applicable Time, did not include any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that this representation and warranty shall not apply to statements or omissions made in an Issuer Free Writing Prospectus in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through Xxxxxxx, Xxxxx & Co. expressly for use therein;

(d) The documents incorporated by reference in the Pricing Prospectus and the Prospectus, when they became effective or were filed with the Commission, as the case may be, conformed in all material respects to the requirements of the Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder, and none of such documents contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not misleading; any further documents so filed and incorporated by reference in the Prospectus or any further amendment or supplement thereto, when such documents become effective or are filed with the Commission, as the case may be, will conform in all material respects to the requirements of the Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder and will not contain an 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; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with

information furnished in writing to the Company by an Underwriter through Xxxxxxx, Sachs & Co. expressly for use therein; and no such documents were filed with the Commission since the Commission’s close of business on the business day immediately prior to the date of this Agreement and prior to the execution of this Agreement, except as set forth on Schedule II(b) hereto;

(e) The Registration Statement conforms and will conform, in all material respects to the requirements of the Act and the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”) and the rules and regulations of the Commission thereunder and the Registration Statement, the Prospectus and any further amendments or supplements to the Registration Statement or the Prospectus do not and will not, as of the applicable effective date as to each part of the Registration Statement and as of the applicable filing date as to the Prospectus and any amendment or supplement thereto, contain an 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; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through Xxxxxxx, Xxxxx & Co. expressly for use therein;

(f) The Company has not sustained since the date of the latest audited financial statements included or incorporated by reference in the Pricing Prospectus any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Pricing Prospectus; and, since the respective dates as of which information is given in the Registration Statement and the Pricing Prospectus, there has not been any change in the capital stock (except for changes made in the ordinary course of business consistent with past practice pursuant to the Company’s equity plans disclosed in the documents filed under the Exchange Act prior to the date of this Agreement and incorporated by reference into the Base Prospectus, the Preliminary Prospectus, the Pricing Prospectus or the Prospectus, and changes pursuant to the exercise of options and warrants outstanding prior to the date of this Agreement) or long term debt of the Company, or any material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, management, financial position, stockholders’ equity or results of operations of the Company, otherwise than as set forth or contemplated in the Pricing Prospectus;

(g) The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of

Delaware, with power and authority (corporate and other) to own its properties and conduct its business as described in the Pricing Prospectus, and has been duly qualified as a foreign corporation for the transaction of business and is in good standing under the laws of each other jurisdiction in which it owns or leases properties or conducts any business so as to require such qualification, or is subject to no material liability or disability by reason of the failure to be so qualified or be in good standing in any such jurisdiction;

(h) The Company has an authorized capitalization as set forth in the Pricing Prospectus and all of the issued shares of capital stock of the Company have been duly and validly authorized and issued and are fully paid and non-assessable; the shares of Stock initially issuable upon conversion of the Securities have been duly and validly authorized and reserved for issuance and, when issued and delivered in accordance with the provisions of the Securities and the Indenture referred to below, will be duly and validly issued, fully paid and non-assessable and will conform to the description of the Stock contained in the Pricing Disclosure Package and the Prospectus;

(i) This Agreement has been duly authorized, executed and delivered by the Company;

(j) The Securities have been duly authorized and, when issued and delivered pursuant to this Agreement and authenticated by the Trustee (as defined below), will have been duly executed, authenticated, issued and delivered and will constitute valid and legally binding obligations of the Company entitled to the benefits provided by the indenture to be dated as of August 12, 2009 (the “Base Indenture”) between the Company and Xxxxx Fargo Bank National Association, as trustee (the “Trustee”), together with the supplemental indenture to be dated as of August 12, 2009 (the “Supplemental Indenture” and together with the Base Indenture, the “Indenture”), under which they are to be issued, which will be substantially in the form to be filed as an exhibit to a Current Report on Form 8-K and incorporated by reference into the Registration Statement, and the Securities when so issued and delivered will be enforceable in accordance with their terms, subject, as to enforcement, to bankruptcy, insolvency, reorganization and other laws of general applicability relating to or affecting creditors’ rights and to general equity principles; the Indenture has been duly authorized and duly qualified under the Trust Indenture Act and, when executed and delivered by the Company and the Trustee, will constitute a valid and legally binding instrument, enforceable in accordance with its terms, subject, as to enforcement, to bankruptcy, insolvency, reorganization and other laws of general applicability relating to or affecting creditors’ rights and to general equity principles; and the Securities and the Indenture will conform to the

descriptions thereof in the Pricing Disclosure Package and the Prospectus;

(k) None of the transactions contemplated by this Agreement (including, without limitation, the use of the proceeds from the sale of the Securities) will violate or result in a violation of Section 7 of the Exchange Act, or any regulation promulgated thereunder, including, without limitation, Regulations T, U, and X of the Board of Governors of the Federal Reserve System;

(l) Prior to the date hereof, neither the Company nor, to the best of the Company’s knowledge, any of its affiliates has taken any action which is designed to or which has constituted or which might have been expected to cause or result in stabilization or manipulation of the price of any security of the Company in connection with the offering of the Securities;

(m) The issue and sale of the Securities and the compliance by the Company with all of the provisions of the Securities, the Indenture and this Agreement and the consummation of the transactions herein and therein contemplated will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject, nor will such action result in any violation of the provisions of the Certificate of Incorporation or By-laws, each as amended through the date of this Agreement, of the Company or any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of their properties; and no consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Securities or the consummation by the Company of the transactions contemplated by this Agreement or the Indenture except such as have been obtained under the Act and the Trust Indenture Act and such consents, approvals, authorizations, registrations or qualifications as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Securities by the Underwriters;

(n) The Company is not (i) in violation of its Certificate of Incorporation or By-laws, each as amended through the date of this Agreement, or (ii) in default in the performance or observance of any obligation, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement, lease or other agreement or instrument to which it is a party or by which it or any of its properties may be bound except, in the case of clause (ii), as will not have a material adverse effect

on the current or future financial position, stockholders’ equity of results of operations of the Company;

(o) The Company has no subsidiaries;

(p) The statements set forth in the Pricing Prospectus and the Prospectus under the caption “Description of Notes” and “Description of Capital Stock”, insofar as they purport to constitute a summary of the terms of the Securities and the Stock, and under the caption “Certain Material U.S. Federal Income Tax Considerations”, insofar as they purport to describe the provisions of the laws and documents referred to therein, are accurate and complete;

(q) The statistical and market-related data included or incorporated by reference in each of the Pricing Disclosure Package and the Prospectus are based on or derived from sources which the Company believes to be reliable and accurate;

(r) Other than as set forth in the Pricing Prospectus, there are no legal or governmental proceedings pending to which the Company is a party or of which any property of the Company is the subject which, if determined adversely to the Company, would individually or in the aggregate have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company; and, to the best of the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others;

(s) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof, will not be an “investment company”, as such term is defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”);

(t) (A) (i) At the time of filing the Registration Statement, (ii) at the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus), and (iii) at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c) under the Act) made any offer relating to the Securities in reliance on the exemption of Rule 163 under the Act, the Company was a “well-known seasoned issuer” as defined in Rule 405 under the Act; and (B) at the earliest time after the filing of the Registration Statement that the Company or another offering participant made a bona fide offer (within the meaning of Rule 164(h)(2) under the Act) of the

Securities, the Company was not an “ineligible issuer” as defined in Rule 405 under the Act;

(u) Ernst & Young LLP which has certified certain financial statements of the Company, and has audited the Company’s internal control over financial reporting, is an independent registered public accounting firm as required by the Act and the rules and regulations of the Commission thereunder;

(v) The Company maintains a system of internal control over financial reporting (as such term is defined in Rule 13a-15(f) under the Exchange Act) that complies with the requirements of the Exchange Act and has been designed by the Company’s principal executive officer and principal financial officer, or under their supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. The Company’s internal control over financial reporting is effective and the Company is not aware of any material weaknesses in its internal control over financial reporting;

(w) Since the date of the latest audited financial statements included or incorporated by reference in the Pricing Prospectus, there has been no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting;

(x) The Company maintains disclosure controls and procedures (as such term is defined in Rule 13a-15(e) under the Exchange Act) that comply with the requirements of the Exchange Act; such disclosure controls and procedures have been designed to ensure that material information relating to the Company is made known to the Company’s principal executive officer and principal financial officer by others within the Company; and such disclosure controls and procedures are effective;

(y) The Company (i) is in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment, natural resources, or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) has received all permits, licenses or other approvals required of it under applicable Environmental Laws to conduct its business and (iii) is in compliance with all terms and conditions of any such permit, license or approval, except where such noncompliance with Environmental Laws, failure to receive required permits, licenses, certificates, other authorizations or approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not, singly or in the aggregate, have a material adverse effect on the current or

future financial position, stockholders’ equity or results of operations of the Company;

(z) To the best of the Company’s knowledge, there are no costs or liabilities associated with Environmental Laws (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties) which would, singly or in the aggregate, have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company;

(aa) Except as described in each of the Pricing Disclosure Package and the Prospectus, the Company owns or possesses adequate licenses or other rights to use all patents, technology, trademarks, trade names and all goodwill associated with the business associated with the foregoing, know-how, trade secrets, copyrights and other intellectual property, including, except to the extent limited by the 1994 Collaboration Agreement and the 2006 Co-Promotion Agreement between Bayer and the Company and any amendments to either of them (the “Bayer Agreements), the right to xxx for past, present and future infringement, dilution, misappropriation of or injury to any of these rights (collectively, “Intellectual Property Rights”) necessary to conduct its business and currently employed or planned to be employed by it in the conduct of its business as described in each of the Pricing Disclosure Package and the Prospectus, and the Company has the exclusive right in the United States to use, sell, and offer for sale the sorafenib compound, including as currently marketed under the trademark “Nexavar”, except to the extent that Bayer HealthCare Pharmaceuticals Inc. (“Bayer”) is so permitted pursuant to the Bayer Agreements. The Company has not received any notice of infringement of or conflict with asserted rights of others with respect to any Intellectual Property Rights which if the subject of a decision, ruling, finding or settlement would reasonably be expected to result in a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company; and the discoveries, inventions, products, product candidates or processes of the Company referred to in the Pricing Disclosure Package and the Prospectus do not, to the knowledge of the Company, infringe any Intellectual Property Right of any third party, or any discovery, invention, product or process that, to the knowledge of the Company, is the object of a patent application filed by any third party, except for any such infringement which would not have a material adverse effect on the current or financial position, stockholders’ equity or results of operations of the Company. There is no patent or, to the Company’s knowledge, any patent application that interferes with the issued claims of any such Intellectual Property Rights, except for any such interference which would not have a

material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company. Except as otherwise disclosed in each of the Pricing Disclosure Package and the Prospectus, there is no pending or threatened in writing action, suit, proceeding or claim by others challenging the validity or scope of such Intellectual Property Rights, which if the subject of an unfavorable decision, would reasonably be expected to, singly or in aggregate, have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company.

(bb) Except as otherwise disclosed in each of the Pricing Disclosure Package and the Prospectus, the Company possesses such valid and current certificates, authorizations or permits issued by the appropriate state, federal or foreign regulatory agencies or bodies necessary to conduct its business, including, without limitation, all necessary U.S. Food and Drug Administration (“FDA”) and similar foreign regulatory approvals except where failure to possess such items would not reasonably be expected to, individually or in the aggregate, have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company and the Company has not received any notice of proceedings relating to the revocation or modification of, or non-compliance with, any such certificate, authorization or permit which, individually or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would reasonably be expected to have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company.

(cc) The Company has filed all tax returns required to be filed through the date hereof and has paid all taxes shown as due on such returns, except in such instances where failure to do so would not have a material adverse effect on the current or future financial position, stockholders’ equity or results of operations of the Company; and except as otherwise disclosed in each of the Pricing Disclosure Package and the Prospectus, there is no material tax deficiency that has been, or could reasonably be expected to be, asserted against the Company or any of its properties or assets;

(dd) Except as described in each of the Pricing Disclosure Package and the Prospectus, there are no material off-balance sheet arrangements (as defined in Item 303 of Regulation S-K) that have or are reasonably likely to have a material current or future effect on the Company’s financial condition, revenues or expenses, changes in financial condition, results of operations, liquidity, capital expenditures or capital resources;

(ee) Except as described in each of the Pricing Disclosure Package and the Prospectus and as preapproved in accordance with the requirements set forth in Section 10A of the Exchange Act, Ernst & Young LLP has not been engaged by the Company to perform any prohibited activities (as described in Section 10A of the Exchange Act);

(ff) The Company’s Board of Directors has validly appointed an audit committee whose composition satisfies the requirements of Rule 5605(c)(2) of the NASDAQ Listing Rules (the “NASDAQ Rules”) and the Board of Directors and/or the audit committee has adopted a charter that satisfies the requirements of Rule 5605(c)(1) of the NASDAQ Rules. The audit committee has reviewed the adequacy of its charter within the past twelve months.

(gg) Neither the Company nor, to the knowledge of the Company, any director, officer, agent, employee or other person associated with or acting on behalf of the Company has (i) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (ii) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds; (iii) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977; or (iv) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment;

(hh) The operations of the Company are and have been conducted at all times in compliance with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, the money laundering statutes of all jurisdictions, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Money Laundering Laws”) and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company with respect to the Money Laundering Laws is pending or, to the knowledge of the Company, threatened;

(ii) Neither the Company nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Department of the Treasury (“OFAC”); and the Company will not directly or indirectly use the proceeds of the offering of the Securities hereunder, or lend, contribute or otherwise make available such proceeds to any joint venture partner or other person or entity, for the purpose of financing the activities of any person currently subject to any U.S. sanctions administered by OFAC; and

(jj) The Company is not a party to any contract, agreement or understanding with any person (other than this Agreement) that would give rise to a valid claim against the Company or any Underwriter for a brokerage commission, finder’s fee or like payment in connection with the offering and sale of the Securities.

2. Subject to the terms and conditions herein set forth, (a) the Company agrees to issue and sell to each of the Underwriters, and each of the Underwriters agrees, severally and not jointly, to purchase from the Company, at a purchase price of 97% of the principal amount thereof, the principal amount of Securities set forth opposite the name of such Underwriter in Schedule I hereto, and (b) in the event and to the extent that the Underwriters shall exercise the election to purchase Optional Securities as provided below, the Company agrees to issue and sell to each of the Underwriters, and each of the Underwriters agrees, severally and not jointly, to purchase from the Company, at the same purchase price set forth in clause (a) of this Section 2, that portion of the aggregate principal amount of the Optional Securities as to which such election shall have been exercised (to be adjusted by you so as to eliminate fractions of $1,000), determined by multiplying such aggregate principal amount of Optional Securities by a fraction, the numerator of which is the maximum aggregate principal amount of Optional Securities which such Underwriter is entitled to purchase as set forth opposite the name of such Underwriter in Schedule I hereto and the denominator of which is the maximum aggregate principal amount of Optional Securities which all of the Underwriters are entitled to purchase hereunder.

The Company hereby grants to the Underwriters the right to purchase at their election up to $30,000,000 aggregate principal amount of Optional Securities, at the same purchase price set forth in clause (a) of the first paragraph of this Section 2. Any such election to purchase Optional Securities may be exercised by written notice from Xxxxxxx, Xxxxx & Co. to the Company, given within a period of 30 calendar days after the date of this Agreement, setting forth the aggregate principal amount of Optional Securities to be purchased and the date on which such Optional Securities are to be delivered, as determined by Xxxxxxx, Sachs & Co. but in no event earlier than the First Time of Delivery (as defined in Section (4)(a) hereof) or, unless Xxxxxxx, Xxxxx & Co. and the Company otherwise agree in writing, earlier than one or later than ten business days after the date of such notice.

3. Upon the authorization by you of the release of the Firm Securities, the several Underwriters propose to offer the Firm Securities for sale upon the terms and conditions set forth in the Prospectus.

4. (a) The Securities to be purchased by each Underwriter hereunder will be represented by one or more definitive global Securities in book-entry form which will be deposited by or on behalf of the Company with The Depository

Trust Company (“DTC”) or its designated custodian. The Company will deliver the Securities to Xxxxxxx, Sachs & Co., for the account of each Underwriter, against payment by or on behalf of such Underwriter of the purchase price therefor by wire transfer of Federal (same-day) funds to the account specified by the Company to Xxxxxxx, Xxxxx & Co. at least forty-eight hours in advance, by causing DTC to credit the Securities to the account of Xxxxxxx, Sachs & Co. at DTC. The Company will cause the certificates representing the Securities to be made available to Xxxxxxx, Xxxxx & Co. for checking at least twenty-four hours prior to the Time of Delivery (as defined below) at the office of Xxxxx Xxxx & Xxxxxxxx LLP, 0000 Xx Xxxxxx Xxxx, Xxxxx Xxxx, Xxxxxxxxxx 00000 (the “Closing Location”). The time and date of such delivery and payment shall be, with respect to the Firm Securities, 10:00 a.m., New York City time, on August 12, 2009 or such other time and date as you and the Company may agree upon in writing, and with respect to the Optional Securities, 10:00 a.m., New York City Time, on the date specified by you in the written notice given by you of the Underwriters’ election to purchase such Optional Securities, or such other time and date as you and the Company may agree upon in writing. Such time and date for delivery of the Firm Securities is herein called the “First Time of Delivery”, the time and date for delivery of any Optional Securities is herein called the “Subsequent Time of Delivery”, and each such time and date for delivery is herein called a “Time of Delivery”.

(b) The documents to be delivered at any Time of Delivery by or on behalf of the parties hereto pursuant to Section 8(k) hereof, including the cross-receipt for the Securities and any additional documents requested by the Underwriters pursuant to Section 8(k) hereof, will be delivered at the Closing Location, and the Securities will be delivered at the DTC (or its designated custodian), all at such Time of Delivery. A meeting will be held at the Closing Location at 7:00 p.m., New York City time, on the New York Business Day next preceding the Time of Delivery, at which meeting the final drafts of the documents to be delivered pursuant to the preceding sentence will be available for review by the parties hereto. For the purposes of this Section 4, “New York Business Day” shall mean each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on which banking institutions in New York City are generally authorized or obligated by law or executive order to close.

5. The Company agrees with each of the Underwriters:

(a) To prepare the Prospectus in a form approved by you and to file such Prospectus pursuant to Rule 424(b) under the Act not later than the Commission’s close of business on the second business day following the date of this Agreement; to make no further amendment or any supplement to the Registration Statement, the Basic Prospectus or the Prospectus prior to the Time of Delivery which shall be disapproved by you promptly after reasonable notice thereof; to advise you, promptly after it receives notice thereof, of the time when any amendment to the Registration Statement has been filed or becomes

effective or any amendment or supplement to the Prospectus has been filed and to furnish you with copies thereof; to prepare a final term sheet, containing solely descriptions of the Securities and the Stock, in a form approved by you and to file such term sheet pursuant to Rule 433(d) under the Act within the time required by such Rule; to file promptly all other material required to be filed by the Company with the Commission pursuant to Rule 433(d) under the Act; to file promptly all reports and any definitive proxy or information statements required to be filed by the Company with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of the Prospectus and for so long as the delivery of a prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is required in connection with the offering or sale of the Securities; to advise you, promptly after it receives notice thereof, of the issuance by the Commission of any stop order or of any order preventing or suspending the use of any Preliminary Prospectus or other prospectus in respect of the Securities, of any notice of objection of the Commission to the use of the Registration Statement or any post-effective amendment thereto pursuant to Rule 401(g)(2) under the Act, of the suspension of the qualification of the Securities or the shares of Stock issuable upon conversion of the Securities for offering or sale in any jurisdiction, of the initiation or threatening of any proceeding for any such purpose, or of any request by the Commission for the amending or supplementing of the Registration Statement or the Prospectus or for additional information; and, in the event of the issuance of any stop order or of any order preventing or suspending the use of any Preliminary Prospectus or other prospectus or suspending any such qualification, to promptly use its best efforts to obtain the withdrawal of such order; and in the event of any such issuance of a notice of objection, promptly to take such steps including, without limitation, amending the Registration Statement or filing a new registration statement, at its own expense, as may be necessary to permit offers and sales of the Securities by the Underwriters (references herein to the Registration Statement shall include any such amendment or new registration statement);

(b) If required by Rule 430B(h) under the Act, to prepare a form of prospectus in a form approved by you and to file such form of prospectus pursuant to Rule 424(b) under the Act not later than may be required by Rule 424(b) under the Act; and to make no further amendment or supplement to such form of prospectus which shall be disapproved by you promptly after reasonable notice therereof;

(c) If by the third anniversary (the “Renewal Deadline”) of the initial effective date of the Registration Statement, any of the Securities remain unsold by the Underwriters, the Company will file, if it has not already done so and is eligible to do so, a new automatic shelf registration statement relating to the Securities, in a form satisfactory to you. If at the Renewal Deadline the Company is no longer eligible to file an automatic shelf registration statement, the Company will, if it has not already done so, file a new shelf registration statement relating to the Securities, in a form satisfactory to you and will use its best efforts to cause

such registration statement to be declared effective within 180 days after the Renewal Deadline. The Company will take all other action necessary or appropriate to permit the public offering and sale of the Securities to continue as contemplated in the expired registration statement relating to the Securities. References herein to the Registration Statement shall include such new automatic shelf registration statement or such new shelf registration statement, as the case may be;

(d) Promptly from time to time to take such action as you may reasonably request to qualify the Securities and the shares of Stock issuable upon conversion of the Securities for offering and sale under the securities laws of such jurisdictions as you may request and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions for as long as may be necessary to complete the distribution of the Securities, provided that in connection therewith the Company shall not be required to qualify as a foreign corporation or to file a general consent to service of process in any jurisdiction;

(e) Prior to 10:00 a.m., New York City time, on the New York Business Day next succeeding the date of this Agreement and from time to time, to furnish the Underwriters with written and electronic copies of the Prospectus in New York City in such quantities as you may reasonably request, and, if the delivery of a prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is required at any time prior to the expiration of nine months after the time of issue of the Prospectus in connection with the offering or sale of the Securities and the shares of Stock issuable upon conversion of the Securities and if at such time any event shall have occurred as a result of which the Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made when such Prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is delivered, not misleading, or, if for any other reason it shall be necessary or desirable during such same period to amend or supplement the Prospectus or to file under the Exchange Act any document incorporated by reference in the Prospectus in order to comply with the Act, the Exchange Act or other applicable law, to notify you and upon your request to file such document and to prepare and furnish without charge to each Underwriter and to any dealer in securities as many written and electronic copies as you may from time to time reasonably request of an amended Prospectus or a supplement to the Prospectus which will correct such statement or omission or effect such compliance; and in case any Underwriter is required to deliver a prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) in connection with sales of any of the Securities and the shares of Stock issuable upon conversion of the Securities at any time nine months or more after the time of issue of the Prospectus, upon your request but at the expense of such Underwriter, to prepare and deliver to such Underwriter as many written and electronic copies as you may request of

an amended or supplemented Prospectus complying with Section 10(a)(3) of the Act;

(f) To make generally available to its securityholders as soon as practicable, but in any event not later than sixteen months after the effective date of the Registration Statement (as defined in Rule 158(c) under the Act), an earnings statement (which need not be audited) of the Company and its subsidiaries, if any, complying with Section 11(a) of the Act and the rules and regulations of the Commission thereunder (including, at the option of the Company, Rule 158);

(g) During the period beginning from the date hereof and continuing until 60 days after the date of the Prospectus, not to offer, sell, contract to sell, pledge, grant any option to purchase, make any short sale or otherwise dispose of, except as provided hereunder, any securities of the Company that are substantially similar to the Securities or the Stock, including but not limited to any options or warrants to purchase shares of Stock or any securities that are convertible into or exchangeable for, or that represent the right to receive, Stock or any such substantially similar securities, in each case without your prior written consent, except for (i) issuances of shares of Stock pursuant to employee stock option plans existing on, or upon the conversion or exchange of convertible or exchangeable securities outstanding as of, the date of this Agreement; (ii) the sale of the Securities under this Agreement and the issuance of Stock upon the conversion of the Securities; (iii) the sale and issuance of 4,000,000 shares of Stock (or up to 4,600,000 shares of Stock if the underwriters exercise in full their option to purchase additional shares) pursuant to the terms of an underwriting agreement, dated as of even date herewith between the Company and the Underwriters (the “Common Stock Agreement”); and (iv) any agreement providing for (A) the contingent future issuance of shares of Stock upon achievement of specified technical or financial milestones and/or (B) the assumption of equity incentives and/or equity incentive plans, provided that no shares of Stock shall be issuable pursuant to any such agreement until at least 60 days after the date of the Prospectus.

(h) To pay the required Commission filing fees relating to the Securities within the time required by Rule 456(b)(1) under the Act without regard to the proviso therein and otherwise in accordance with Rules 456(b) and 457(r) under the Act;

(i) To use the net proceeds received by it from the sale of the Securities pursuant to this Agreement in the manner specified in the Pricing Prospectus under the caption “Use of Proceeds”;

(j) To reserve and keep available at all times, free of preemptive rights, shares of Stock for the purpose of enabling the Company to satisfy any obligation to issue shares of its Stock upon conversion of the Securities; and

(k) To use its best efforts to list, subject to notice of issuance, the shares of Stock issuable upon conversion of the Securities on the on the NASDAQ Global Select Market (“NASDAQ”).

(a) (i) The Company represents and agrees that, other than the final term sheet prepared and filed pursuant to Section 5(a) hereof, without the prior consent of Xxxxxxx, Xxxxx & Co., it has not made and will not make any offer relating to the Securities that would constitute a “free writing prospectus” as defined in Rule 405 under the Act;

(ii) each Underwriter represents and agrees that, without the prior consent of the Company and Xxxxxxx, Sachs & Co., other than one or more term sheets relating to the Securities containing customary information and conveyed to purchasers of Securities, it has not made and will not make any offer relating to the Securities that would constitute a “free writing prospectus” as defined in Rule 405 under the Act; and

(iii) any such free writing prospectus the use of which has been consented to by the Company and Xxxxxxx, Xxxxx & Co. (including the final term sheet prepared and filed pursuant to Section 5(a) hereof) is listed on Schedule II(a) hereto;

(b) The Company has complied and will comply with the requirements of Rule 433 under the Act applicable to any Issuer Free Writing Prospectus, including timely filing with the Commission or retention where required and legending; and

(c) The Company agrees that if at any time following issuance of an Issuer Free Writing Prospectus any event occurred or occurs as a result of which such Issuer Free Writing Prospectus would conflict with the information in the Registration Statement, the Pricing Prospectus or the Prospectus or would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances then prevailing, not misleading, the Company will give prompt notice thereof to Xxxxxxx, Sachs & Co. and, if requested by Xxxxxxx, Xxxxx & Co., will prepare and furnish without charge to each Underwriter an Issuer Free Writing Prospectus or other document which will correct such conflict, statement or omission; provided, however, that this representation and warranty shall not apply to any statements or omissions in an Issuer Free Writing Prospectus made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through Xxxxxxx, Sachs & Co. expressly for use therein.

7. The Company covenants and agrees with the several Underwriters that the Company will pay or cause to be paid the following: (i) the fees, disbursements and expenses of the Company’s counsel and accountants in connection with the registration of the Securities and the shares of Stock issuable upon conversion of the Securities under the Act and all other expenses in connection with the preparation, printing, reproduction and filing of the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, any Issuer Free Writing Prospectus and the Prospectus and amendments and supplements thereto and the mailing and delivering of copies thereof to the Underwriters and dealers; (ii) the cost of printing or reproducing any Agreement among Underwriters, this Agreement, the Indenture, the Blue Sky Memorandum, closing documents (including any compilations thereof) and any other documents in connection with the offering, purchase, sale and delivery of the Securities; (iii) all expenses in connection with the qualification of the Securities and the shares of Stock issuable upon conversion of the Securities for offering and sale under state securities laws as provided in Section 5(d) hereof, including the reasonable fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky and legal investment surveys; (iv) any fees charged by securities rating services for rating the Securities; (v) the filing fees incident to, and the reasonable fees and disbursements of counsel for the Underwriters in connection with, any required review by the Financial Fiduciary Regulatory Authority (“FINRA”) of the terms of the sale of the Securities; (vi) the cost of the preparation, issuance and delivery of the Securities; (vii) all costs and expenses related to the transfer and delivery of the Securities to the Underwriters, including any transfer or other taxes payable thereon; (viii) the fees and expenses of the Trustee and any agent of the Trustee and the fees and disbursements of counsel for the Trustee in connection with the Indenture and the Securities, and the costs and charges of any transfer agent, registrar or depositary; (ix) all fees and expenses in connection with listing the Securities or the shares of Stock issuable upon connection of the Securities; upon conversion of the Securities; (x) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the offering of the Securities, including expenses associated with the preparation or dissemination of any electronic road show, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations with the prior approval of the Company, travel and lodging expenses of the officers and employees of the Company; and (xi) all other costs and expenses incident to the performance of its obligations hereunder which are not otherwise specifically provided for in this Section. It is understood, however, that, except as provided in this Section, and Sections 9 and 12 hereof, the Underwriters will pay all of their own costs and expenses, including the fees of their counsel, transfer taxes on resale of any of the Securities by them, and any advertising expenses connected with any offers they may make.

8. The obligations of the Underwriters hereunder at any Time of Delivery shall be subject, in their discretion, to the condition that all representations and warranties and other statements of the Company herein are, at and as of such Time of Delivery, true and correct, the condition that the Company shall have performed all of its obligations hereunder theretofore to be performed, and the following additional conditions:

(a) The Prospectus shall have been filed with the Commission pursuant to Rule 424(b) under the Act within the applicable time period prescribed for such filing by the rules and regulations under the Act and in accordance with Section 5(a) hereof; the final term sheet contemplated by Section 5(a) hereof, and any other material required to be filed by the Company pursuant to Rule 433(d) under the Act, shall have been filed with the Commission within the applicable time periods prescribed for such filings by Rule 433; no stop order suspending the effectiveness of the Registration Statement or any part thereof shall have been issued and no proceeding for that purpose shall have been initiated or threatened by the Commission and no notice of objection of the Commission to the use of the Registration Statement or any post-effective amendment thereto pursuant to Rule 401(g)(2) under the Act shall have been received; no stop order suspending or preventing the use of the Prospectus or any Issuer Free Writing Prospectus shall have been initiated or threatened by the Commission; and all requests for additional information on the part of the Commission shall have been complied with to your reasonable satisfaction;

(b) Xxxxx Xxxx & Xxxxxxxx LLP, counsel for the Underwriters, shall have furnished to you such written opinion or opinions dated such Time of Delivery, in form and substance satisfactory to you, with respect to the matters as you may reasonably request, and such counsel shall have received such papers and information as they may reasonably request to enable them to pass upon such matters;

(c) Xxxxxx Godward Kronish LLP, counsel for the Company, shall have furnished to you their written opinion, dated such Time of Delivery, in substantially the form attached hereto as Exhibit A;

(d) On the date of the Prospectus at a time prior to the execution of this Agreement, at 9:30 a.m., New York City time, on the effective date of any post effective amendment to the Registration Statement filed subsequent to the date of this Agreement and also at each Time of Delivery, Ernst & Young LLP shall have furnished to you a letter or letters containing statements and information of the type ordinarily included in accountants’ “comfort letters,” dated the respective dates of delivery thereof, in form and substance satisfactory to you (the executed copy of the letter delivered prior to the execution of this Agreement is attached as Exhibit B hereto;

(e) (i) The Company shall not have sustained since the date of the latest audited financial statements included or incorporated by reference in the Pricing Prospectus any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Pricing Prospectus, and (ii) since the respective dates as of which information is given in the Pricing Prospectus there shall not have been any change in the capital stock or long term debt of the Company or any of its subsidiaries, if any, or any change, or any development involving a prospective change, in or affecting the general affairs, management, financial position, stockholders’ equity or results of operations of the Company, otherwise than as set forth or contemplated in the Pricing Prospectus, the effect of which, in any such case described in clause (i) or (ii), is in your judgment so material and adverse as to make it impracticable or inadvisable to proceed with the public offering or the delivery of the Securities being issued at such Time of Delivery on the terms and in the manner contemplated in the Prospectus;

(f) On or after the Applicable Time (i) no downgrading shall have occurred in the rating accorded the Company’s debt securities by any “nationally recognized statistical rating organization”, as that term is defined by the Commission for purposes of Rule 436(g)(2) under the Act, and (ii) no such organization shall have publicly announced that it has under surveillance or review, with possible negative implications, its rating of any of the Company’s debt securities;

(g) On or after the Applicable Time there shall not have occurred any of the following: (i) a suspension or material limitation in trading in securities generally on the New York Stock Exchange or on NASDAQ; (ii) a suspension or material limitation in trading in the Company’s securities on NASDAQ; (iii) a general moratorium on commercial banking activities declared by either Federal or New York or California State authorities or a material disruption in commercial banking or securities settlement or clearance services in the United States; (iv) the outbreak or escalation of hostilities involving the United States or the declaration by the United States of a national emergency or war or (v) the occurrence of any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any such event specified in clause (iv) or (v) in your judgment makes it impracticable or inadvisable to proceed with the public offering or the delivery of the Securities being issued at such Time of Delivery on the terms and in the manner contemplated in the Prospectus;

(h) The Company shall have submitted an additional share listing application to list the shares of Stock issuable upon conversion of the Securities on NASDAQ, and NASDAQ shall not have disapproved the listing of such shares, subject to notice of issuance, for listing on NASDAQ;

(i) The Company shall have obtained and delivered to the Underwriters executed copies of a lock-up agreement in the form attached hereto as Exhibit C from each of the persons listed on Schedule IV; and

(j) The Company shall have furnished or caused to be furnished to you at such Time of Delivery certificates of officers of the Company satisfactory to you as to the accuracy of the representations and warranties of the Company herein at and as of such Time of Delivery, as to the performance by the Company of all of its obligations hereunder to be performed at or prior to such Time of Delivery, as to the matters set forth in subsections (a) and (e) of this Section and as to such other matters as you may reasonably request.

9. (a) The Company will indemnify and hold harmless each Underwriter against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, any Issuer Free Writing Prospectus or any “issuer information” filed or required to be filed pursuant to Rule 433(d) under the Act, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by such Underwriter in connection with investigating or defending any such action or claim as such expenses are incurred; provided, however, that the Company shall not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by any Underwriter through Xxxxxxx, Xxxxx & Co. expressly for use therein.

(b) Each Underwriter will indemnify and hold harmless the Company against any losses, claims, damages or liabilities to which the Company may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not

misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, the Pricing Prospectus or the Prospectus or any such amendment or supplement thereto, or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by such Underwriter through Xxxxxxx, Sachs & Co. expressly for use therein; and will reimburse the Company for any legal or other expenses reasonably incurred by the Company in connection with investigating or defending any such action or claim as such expenses are incurred.

(c) Promptly after receipt by an indemnified party under subsection (a) or (b) above of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under such subsection, notify the indemnifying party in writing of the commencement thereof; but the omission so to notify the indemnifying party shall not relieve it from any liability which it may have to any indemnified party otherwise than under such subsection. In case any such action shall be brought against any indemnified party and it shall notify the indemnifying party of the commencement thereof, the indemnifying party shall be entitled to participate therein and, to the extent that it shall wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and, after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party shall not be liable to such indemnified party under such subsection for any legal expenses of other counsel or any other expenses, in each case subsequently incurred by such indemnified party, in connection with the defense thereof other than reasonable costs of investigation. No indemnifying party shall, without the written consent of the indemnified party, effect the settlement or compromise of, or consent to the entry of any judgment with respect to, any pending or threatened action or claim in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified party is an actual or potential party to such action or claim) unless such settlement, compromise or judgment (i) includes an unconditional release of the indemnified party from all liability arising out of such action or claim and (ii) does not include a statement as to or an admission of fault, culpability or a failure to act, by or on behalf of any indemnified party.

(d) If the indemnification provided for in this Section 9 is unavailable to or insufficient to hold harmless an indemnified party under subsection (a) or (b) above in respect of any losses, claims, damages or liabilities (or actions in respect thereof) referred to therein, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (or actions in respect thereof) in such proportion as is appropriate to reflect the relative benefits received by the

Company on the one hand and the Underwriters on the other from the offering of the Securities. If, however, the allocation provided by the immediately preceding sentence is not permitted by applicable law or if the indemnified party failed to give the notice required under subsection (c) above, then each indemnifying party shall contribute to such amount paid or payable by such indemnified party in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and the Underwriters on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities (or actions in respect thereof), as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover page of the Prospectus. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company on the one hand or the Underwriters on the other and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this subsection (d) were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation which does not take account of the equitable considerations referred to above in this subsection (d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages or liabilities (or actions in respect thereof) referred to above in this subsection (d) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this subsection (d), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages which such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Underwriters’ obligations in this subsection (d) to contribute are several in proportion to their respective underwriting obligations and not joint.

(e) The obligations of the Company under this Section 9 shall be in addition to any liability which the Company may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Underwriter within the meaning of the Act and each broker-dealer affiliate of any Underwriter; and the obligations of the Underwriters under this Section 9 shall be

in addition to any liability which the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each officer and director of the Company and to each person, if any, who controls the Company within the meaning of the Act.

10. (a) If any Underwriter shall default in its obligation to purchase the Securities which it has agreed to purchase hereunder at a Time of Delivery, you may in your discretion arrange for you or another party or other parties to purchase such Securities on the terms contained herein. If within thirty-six hours after such default by any Underwriter you do not arrange for the purchase of such Securities, then the Company shall be entitled to a further period of thirty-six hours within which to procure another party or other parties satisfactory to you to purchase such Securities on such terms. In the event that, within the respective prescribed periods, you notify the Company that you have so arranged for the purchase of such Securities, or the Company notifies you that it has so arranged for the purchase of such Securities, you or the Company shall have the right to postpone such Time of Delivery for a period of not more than seven days, in order to effect whatever changes may thereby be made necessary in the Registration Statement or the Prospectus, or in any other documents or arrangements, and the Company agrees to file promptly any amendments or supplements to the Registration Statement or the Prospectus which in your opinion may thereby be made necessary. The term “Underwriter” as used in this Agreement shall include any person substituted under this Section with like effect as if such person had originally been a party to this Agreement with respect to such Securities.

(b) If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Underwriter or Underwriters by you and the Company as provided in subsection (a) above, the aggregate principal amount of such Securities which remains unpurchased does not exceed one-eleventh of the aggregate principal amount of all the Securities to be purchased at such Time of Delivery, then the Company shall have the right to require each non-defaulting Underwriter to purchase the principal amount of Securities which such Underwriter agreed to purchase hereunder at such Time of Delivery and, in addition, to require each non-defaulting Underwriter to purchase its pro rata share (based on the principal amount of Securities which such Underwriter agreed to purchase hereunder) of the Securities of such defaulting Underwriter or Underwriters for which such arrangements have not been made; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

(c) If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Underwriter or Underwriters by you and the Company as provided in subsection (a) above, the aggregate principal amount of Securities which remains unpurchased exceeds one eleventh of the aggregate principal amount of all the Securities to be purchased at such Time of Delivery, or if the Company shall not exercise the right described in subsection (b) above to require

non-defaulting Underwriters to purchase Securities of a defaulting Underwriter or Underwriters, then this Agreement (or, with respect to any Subsequent Time of Delivery, the obligation of the Underwriters to purchase and of the Company to sell the Optional Securities) shall thereupon terminate, without liability on the part of any non-defaulting Underwriter or the Company, except for the expenses to be borne by the Company and the Underwriters as provided in Section 7 hereof and the indemnity and contribution agreements in Section 9 hereof; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

11. The respective indemnities, agreements, representations, warranties and other statements of the Company and the several Underwriters, as set forth in this Agreement or made by or on behalf of them, respectively, pursuant to this Agreement, shall remain in full force and effect, regardless of any investigation (or any statement as to the results thereof) made by or on behalf of any Underwriter or any affiliate or controlling person of any Underwriter, or the Company, or any officer or director or controlling person of the Company, and shall survive delivery of and payment for the Securities.

12. If this Agreement shall be terminated pursuant to Section 10 hereof, the Company shall not then be under any liability to any Underwriter except as provided in Sections 7 and 9 hereof; but, if for any other reason, any Securities are not delivered by or on behalf of the Company as provided herein, the Company will reimburse the Underwriters through you for all expenses approved in writing by you, including fees and disbursements of counsel, reasonably incurred by the Underwriters in making preparations for the purchase, sale and delivery of the Securities, but the Company shall then be under no further liability to any Underwriter except as provided in Sections 7 and 9 hereof.

13. In all dealings hereunder, you shall act on behalf of each of the Underwriters, and the parties hereto shall be entitled to act and rely upon any statement, request, notice or agreement on behalf of any Underwriter made or given by you jointly or by Xxxxxxx, Xxxxx & Co. on behalf of you as the representatives.

All statements, requests, notices and agreements hereunder shall be in writing, and if to the Underwriters shall be delivered or sent by mail, telex or facsimile transmission to you as the representatives in care of Xxxxxxx, Sachs & Co., 00 Xxxxx Xxxxxx, 00xx Xxxxx, Xxx Xxxx, Xxx Xxxx 00000, Attention: Registration Department; and if to the Company shall be delivered or sent by mail, telex or facsimile transmission to the address of the Company set forth in the Registration Statement, Attention: Chief Financial Officer; provided, however, that any notice to an Underwriter pursuant to Section 9(c) hereof shall be delivered or sent by mail, telex or facsimile transmission to such Underwriter at its address set forth in its Underwriters’ Questionnaire, or telex constituting such Questionnaire, which address will be supplied to the Company by you upon

request. Any such statements, requests, notices or agreements shall take effect upon receipt thereof.

In accordance with the requirements of the USA Patriot Act (Title III of Pub. L. 107-56 (signed into law October 26, 2001)), the underwriters are required to obtain, verify and record information that identifies their respective clients, including the Company, which information may include the name and address of their respective clients, as well as other information that will allow the underwriters to properly identify their respective clients.

14. This Agreement shall be binding upon, and inure solely to the benefit of, the Underwriters, the Company and, to the extent provided in Sections 9 and 11 hereof, the officers and directors of the Company and each person who controls the Company or any Underwriter, and their respective heirs, executors, administrators, successors and assigns, and no other person shall acquire or have any right under or by virtue of this Agreement. No purchaser of any of the Securities from any Underwriter shall be deemed a successor or assign by reason merely of such purchase.

15. Time shall be of the essence of this Agreement. As used herein, the term “business day” shall mean any day when the Commission’s office in Washington, D.C. is open for business.

16. The Company acknowledges and agrees that (i) the purchase and sale of the Securities pursuant to this Agreement is an arm’s-length commercial transaction between the Company, on the one hand, and the several Underwriters, on the other, (ii) in connection therewith and with the process leading to such transaction each Underwriter is acting solely as a principal and not the agent or fiduciary of the Company, (iii) no Underwriter has assumed an advisory or fiduciary responsibility in favor of the Company with respect to the offering contemplated hereby or the process leading thereto (irrespective of whether such Underwriter has advised or is currently advising the Company on other matters) or any other obligation to the Company except the obligations expressly set forth in this Agreement and (iv) the Company has consulted its own legal and financial advisors to the extent it deemed appropriate. The Company agrees that it will not claim that the Underwriters, or any of them, has rendered advisory services of any nature or respect, or owes a fiduciary or similar duty to the Company, in connection with such transaction or the process leading thereto.

17. This Agreement supersedes all prior agreements and understandings (whether written or oral) between the Company and the Underwriters, or any of them, with respect to the subject matter hereof.

18. This Agreement shall be governed by and construed in accordance with the laws of the State of New York.

19. The Company and each of the Underwriters hereby irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to this Agreement or the transactions contemplated hereby.

20. This Agreement may be executed by any one or more of the parties hereto in any number of counterparts, each of which shall be deemed to be an original, but all such respective counterparts shall together constitute one and the same instrument.

21. Notwithstanding anything herein to the contrary, the Company is authorized to disclose to any persons the U.S. federal and state income tax treatment and tax structure of the potential transaction and all materials of any kind (including tax opinions and other tax analyses) provided to the Company relating to that treatment and structure, without the Underwriters, imposing any limitation of any kind. However, any information relating to the tax treatment and tax structure shall remain confidential (and the foregoing sentence shall not apply) to the extent necessary to enable any person to comply with securities laws. For this purpose, “tax structure” is limited to any facts that may be relevant to that treatment.

If the foregoing is in accordance with your understanding, please sign and return to us four counterparts hereof, and upon the acceptance hereof by you, on behalf of each of the Underwriters, this letter and such acceptance hereof shall constitute a binding agreement between each of the Underwriters and the Company. It is understood that your acceptance of this letter on behalf of each of the Underwriters is pursuant to the authority set forth in a form of Agreement among Underwriters, the form of which shall be submitted to the Company for examination upon request, but without warranty on your part as to the authority of the signers thereof.


Very truly yours, Onyx Pharmaceuticals, Inc.
By:	/s/ Xxxxxxx X. Xxxx
	Name:	Xxxxxxx X. Xxxx
	Title:	Executive Vice President and Chief Financial Officer


Accepted as of the date hereof: Xxxxxxx, Xxxxx & Co.
By:	/s/ Xxxxxxx, Sachs & Co.
	(Xxxxxxx, Xxxxx & Co.)
	On behalf of each of the Underwriters

[Signature Page to Convertible Senior Notes Underwriting Agreement]

SCHEDULE I


			Aggregate Principal
			Amount of Optional
			Securities to be
	Principal Amount of		Purchased if
	Firm Securities to		Maximum Option
Underwriter	be Purchased		Exercised
Xxxxxxx, Sachs & Co.	$	140,535,000	$	21,080,250
X.X. Xxxxxx Securities Inc.		30,275,000		4,541,250
Barclays Capital Inc.		18,375,000		2,756,250
Lazard Capital Markets LLC		10,815,000		1,622,250

Total	$	200,000,000	$	30,000,000

I-1

SCHEDULE II

(a) Issuer Free Writing Prospectuses not included in the Pricing Disclosure Package: None

(b) Additional Documents Incorporated by Reference: None

II-1

SCHEDULE III

Onyx Pharmaceuticals, Inc.
Concurrent Offerings of

4,000,000 Shares of Common Stock, par value $0.001 per share
(the “Common Stock Offering”)

and

$200,000,000 principal amount of
4.00% Convertible Senior Notes due 2016
(the “Convertible Senior Notes Offering”)

The information in this pricing term sheet relates only to the Common Stock Offering and Convertible Senior Notes Offering and should be read together with (i) the preliminary prospectus supplement dated August 4, 2009 relating to the Common Stock Offering, including the documents incorporated by reference therein, (ii) the preliminary prospectus supplement dated August 4, 2009 relating to the Convertible Senior Notes Offering, including the documents incorporated by reference therein, and (iii) the related base prospectus dated June 18, 2007, each filed pursuant to Rule 424(b) under the Securities Act of 1933, as amended.


Issuer:		Onyx Pharmaceuticals, Inc., a Delaware corporation.

Ticker / Exchange for Common Stock:		ONXX / The NASDAQ Global Market (“NASDAQ”).

Trade Date:		August 6, 2009.

Settlement Date:		August 12, 2009.

Common Stock Offering

Title of Securities:		Common stock, par value $0.001 per share, of the Issuer (the “Common Stock”).

Shares Offered and Sold:		4,000,000 (or a total of 4,600,000 if the underwriters exercise in full their option to purchase up to 600,000 additional shares of the Issuer’s common stock).

Last Reported Sale Price of Common Stock on NASDAQ on August 6, 2009:		$30.67 per share of Common Stock.

Public Offering Price:		$30.50 per share of Common Stock.

Use of Proceeds:		The Issuer estimates that the net proceeds from the Common Stock Offering will be approximately $116.6 million (or approximately $134.1 million if the underwriters’ option to purchase up to 600,000 additional shares of Common Stock is exercised in full), after deducting the underwriting discounts and commissions and before estimated offering expenses. The Issuer intends to use the net proceeds

III-1


		from the Common Stock Offering and the Convertible Senior Notes Offering to build and diversify the Issuer’s pipeline by in-licensing product candidates or investing in or acquiring businesses or technologies that the Issuer believes are complementary to its own. The Issuer has no current commitments or agreements with respect to any such transactions as of the date of this Pricing Term Sheet. The Issuer may also use a portion of the net proceeds from the Common Stock Offering and the Convertible Senior Notes Offering to fund the costs of its clinical trials program and other research and development activities, both ongoing and planned, as well as sales and marketing activities, and for general corporate purposes, including working capital.

Sole Book-Running Manager:		Xxxxxxx, Xxxxx & Co.

Co-Managers:		X.X. Xxxxxx Securities Inc., Barclays Capital Inc. and Lazard Capital Markets LLC.

CUSIP Number:		000000000

ISIN Number:		US6833991093

Convertible Senior Notes Offering

Convertible Senior Notes:		4.00% Convertible Senior Notes due 2016 (the “Notes”).

Aggregate Principal Amount Offered:		$200 million principal amount of Notes (or a total of $230 million principal amount of Notes if the underwriters exercise in full their option to purchase up to $30 million principal amount of additional Notes).

Maturity:		The Notes will mature on August 15, 2016, unless earlier converted, redeemed by the Issuer or repurchased by the Issuer at the holder’s option upon a fundamental change.

Interest Rate:		4.00% per year.

Interest Payment and Record Dates:		Interest will accrue from the Settlement Date or from the most recent date to which interest has been paid or duly provided for, and will be payable semi-annually in arrears on February 15 and August 15 of each year, beginning on February 15, 2010, to holders of record at the close of business on February 1 or August 1, as the case may be, immediately preceding the relevant Interest Payment Date.

Last Reported Sale Price of Common Stock on NASDAQ on August 6, 2009:		$30.67 per share of Common Stock.

Reference Price:		$30.50 per share of Common Stock, the Public Offering Price per share in the Common Stock Offering.

Conversion Premium:		Approximately 30% above the Reference Price.

Initial Conversion Price:		Approximately $39.65 per share of Common Stock.

III-2



Initial Conversion Rate:		25.2207 shares of Common Stock per $1,000 principal amount of Notes, subject to adjustment.

Call Protection:		The Issuer may not redeem any of the Notes at its option prior to August 20, 2013. Beginning on August 20, 2013, the Issuer may redeem for cash all or part of the Notes if the last reported sale price of the Issuer’s common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the trading day prior to the date the Issuer provides the notice of redemption exceeds 130% of the applicable conversion price. The redemption price will equal the sum of 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest, if any, to, but not including, the redemption date, plus a “make-whole premium” payment in cash, shares of our common stock or a combination of cash and shares of our common stock, at our option, equal to the sum of the present values of the remaining scheduled payments of interest on the notes to be redeemed through August 15, 2016 (excluding interest accrued to, but excluding, the redemption date). The present values of the remaining interest payments will be computed using a discount rate equal to 2.5%.

Use of Proceeds:		The Issuer estimates that the net proceeds from the Convertible Senior Notes Offering will be approximately $193.7 million (or approximately $222.8 million if the underwriters’ option to purchase up to $30 million principal amount of additional Notes is exercised in full), after deducting the underwriting discounts and commissions and before estimated offering expenses. The Issuer intends to use the net proceeds from the Convertible Senior Notes Offering and the Common Stock Offering to build and diversify the Issuer’s pipeline by in-licensing product candidates or investing in or acquiring businesses or technologies that the Issuer believe are complementary to its own. The Issuer has no current commitments or agreements with respect to any such transactions as of the date of this Pricing Term Sheet. The Issuer may also use a portion of the net proceeds from the Convertible Senior Notes Offering and the Common Stock Offering to fund the costs of its clinical trials program and other research and development activities, both ongoing and planned, as well as sales and marketing activities, and for general corporate purposes, including working capital.

Sole Book-Running Manager:		Xxxxxxx, Xxxxx & Co.

Co-Managers:		X.X. Xxxxxx Securities Inc., Barclays Capital Inc. and Lazard Capital Markets LLC.

CUSIP Number:		000000XX0

ISIN Number:		US683399AB58

Adjustment to Conversion Rate Upon Conversion Upon Make-Whole Fundamental Change:		The following table sets forth the number of additional shares of Common Stock to be added to the conversion rate of $1,000 principal amount of Notes for certain conversions in connection with a make-whole fundamental change for each Stock Price and Make-Whole Reference Date set forth below:

III-3


Make-Whole	Stock Price
Reference Date	$30.50		$30.75		$31.50		$33.00		$35.00		$37.50		$40.00		$45.00		$50.00		$55.00		$60.00		$70.00		$80.00		$100.00		$150.00		$200.00
August 12, 2009		7.5662		7.4654		7.2011		6.7199		6.1624		5.5745		5.0822		4.3074		3.7280		3.2796		2.9227		2.3898		2.0101		1.5020		0.8561		0.5451
August 15, 2010		7.5662		7.2996		6.6634		6.1870		5.6393		5.0676		4.5938		3.8588		3.3189		2.9071		2.5832		2.1058		1.7695		1.3227		0.7559		0.4817
August 15, 2011		7.5662		7.2996		6.5254		5.7604		5.2036		4.6296		4.1607		3.4476		2.9368		2.5557		2.2612		1.8356		1.5407		1.1532		0.6630		0.4244
August 15, 2012		7.5662		7.2996		6.5254		5.4045		4.8153		4.2175		3.7382		3.0296		2.5407		2.1880		1.9232		1.5518		1.3012		0.9765		0.5666		0.3656
August 15, 2013		7.5662		7.2996		6.5254		5.0861		4.4334		3.7837		3.2754		2.5533		2.0838		1.7642		1.5357		1.2308		1.0323		0.7783		0.4565		0.2974
August 15, 2014		7.5662		7.2996		6.5254		5.0823		4.0620		3.3145		2.7442		1.9700		1.5038		1.2486		1.0780		0.8636		0.7270		0.5520		0.3276		0.2158
August 15, 2015		7.5662		7.2996		6.5254		5.0823		3.6526		2.7350		2.0707		1.2484		0.7874		0.6510		0.5506		0.4428		0.3759		0.2882		0.1729		0.1150
August 15, 2016		7.5662		7.2996		6.5254		5.0823		3.3507		1.4460		0.0000		0.0000		0.0000		0.0000		0.0000		0.0000		0.0000		0.0000		0.0000		0.0000

The exact stock prices and make-whole reference dates may not be set forth in the table above, in which case if the stock price is between two stock price amounts in the table or the effective date is between make-whole reference dates in the table, the number of additional shares will be determined by a straight-line interpolation between the number of additional shares set forth for the higher and lower stock price amounts and the two make-whole reference dates, as applicable, based on a 365-day year. If the stock price is:

•		greater than $200.00 per share (subject to adjustment in the same manner as the stock prices set forth in the column headings of the table above), the conversion rate will not be increased; or

•		less than $30.50 per share (subject to adjustment in the same manner as the stock prices set forth in the column headings of the table above), the conversion rate will not be increased.

Notwithstanding the foregoing, in no event will the total number of shares of Common Stock issuable upon conversion exceed 32.7869 per $1,000 principal amount of Notes, subject to adjustments in the same manner as the conversion rate as set forth in the preliminary prospectus supplement dated August 4, 2009 for the Convertible Senior Notes Offering entitled ‘‘Description of Notes—Conversion Rate Adjustments.’’

III-4

CAPITALIZATION

The following table replaces (i) the table set forth on page S-31 of the preliminary prospectus supplement for the Common Stock Offering and (ii) the table set forth on page S-40 of the preliminary prospectus supplement for the Convertible Senior Notes Offering:


	As of June 30, 2009
				As
(in thousands)(unaudited)	Actual			Adjusted(1)
Cash and cash equivalents	$	75,449		$	385,764
Marketable securities, current		356,293			356,293
Receivable from collaboration partner		46,380			46,380

Debt:
Convertible senior notes due 2016 (2)		—			200,000
Total debt	$	—		$	200,000

Stockholders’ equity:
Preferred stock, par value $0.001, 5,000 shares authorized; none issued, actual and as adjusted		—			—
Common stock, par value $0.001, 100,000 shares authorized; 56,918 issued and outstanding, actual and 60,918 shares outstanding, as adjusted(1)(2)		57			61
Additional paid-in capital		966,826			1,083,447
Receivable from stock option exercises		(198	)		(198	)
Accumulated other comprehensive loss		(1,365	)		(1,365	)
Accumulated deficit		457,271			457,271

Total stockholders’ equity		508,049			624,674

Total capitalization	$	508,049		$	824,674

(1)

Outstanding shares at June 30, 2009, actual and as adjusted, excludes:

	•		5,180,266 shares of common stock issuable upon exercise of outstanding stock options with a weighted average exercise price of approximately $28.80 per share;

	•		3,184,000 shares of common stock available for future issuance under our stock option plans;

	•		351,639 shares of restricted common stock issued under stock bonus awards;

	•		434,327 shares of common stock available for sale under our employee stock purchase plan; and

	•		5,044,140 shares of common stock reserved for issuance upon conversion of the convertible notes concurrently being offered by us in connection with our notes offering.

(2)

Amount reflects the gross proceeds of the offerings assuming no exercise of the underwriters’ option to purchase additional shares or additional notes. The recording of the notes does not include the application of FASB Staff Position No. APB 14-1, Accounting for Convertible Debt Instruments That May Be Settled in Cash Upon Conversion (Including Partial Cash Settlement), which we expect to adopt in our third fiscal quarter in 2009. Under FSP APB 14-1, an entity must separately account for the liability and equity components of the convertible debt instruments (such as the notes) that may be settled entirely or partially in cash upon conversion in a manner that reflects the issuer’s economic interest cost. The effect of FSP APB 14-1 on the accounting for the notes is that the equity component would be included in the additional paid-in-capital section of stockholders’ equity on our consolidated balance sheet and the value of the equity component would be treated as original issue discount for purposes of accounting for the debt component of the notes.

The Issuer has filed a registration statement (including preliminary prospectus supplements each dated August 4, 2009 and an accompanying prospectus dated June 18, 2007) with the Securities and Exchange Commission, or SEC, for the offerings to which this communication relates. Before you invest, you should read the relevant preliminary prospectus supplement, the accompanying prospectus and the other documents the Issuer has filed with the SEC for more complete information about the Issuer and the offerings. You may get these documents for free by visiting XXXXX on the SEC web site at xxx.xxx.xxx. Alternatively, copies

III-5

may be obtained from Xxxxxxx, Sachs & Co., Attn: Prospectus Department, 00 Xxxxx Xxxxxx, Xxx Xxxx, XX 00000, call toll-free (000) 000-0000, or fax (000) 000-0000, or email xxxxxxxxxx-xx@xx.xxxxx.xx.xxx.

This communication should be read in conjunction with the preliminary prospectus supplements dated August 4, 2009 and the accompanying prospectus. The information in this communication supersedes the information in the relevant preliminary prospectus supplement and the accompanying prospectus to the extent inconsistent with the information in such preliminary prospectus supplement and the accompanying prospectus.

ANY DISCLAIMERS OR OTHER NOTICES THAT MAY APPEAR BELOW ARE NOT APPLICABLE TO THIS COMMUNICATION AND SHOULD BE DISREGARDED. SUCH DISCLAIMERS OR OTHER NOTICES WERE AUTOMATICALLY GENERATED AS A RESULT OF THIS COMMUNICATION BEING SENT VIA BLOOMBERG OR ANOTHER EMAIL SYSTEM.

III-6

SCHEDULE IV

Persons Subject to Lock-Up Letter

Xxxx Xxxxxx

N. Xxxxxxx Xxxxx

Xxxxx X. Xxxxx

Xxxxxxx X. Xxxx

Xxxx Xxxxxxx

Xxxxxxx X. Xxxxxx-Xxxxx

Xxxxxxx Xxxxxxxx

Xxxxxx Xxxxxxxx

Xxxxxxx X. Xxxx

Xxxxxxx Xxxxxxxx

Xxxxxx X. Xxxxxxx

Xxxxxxxx X. Xxxx

XX-1

Exhibit C

Form of Lock-Up Agreement Pursuant to Section 8(j)

Onyx Pharmaceuticals, Inc.

Lock-Up Agreement

August , 2009

Xxxxxxx, Sachs & Co.
00 Xxxxx Xxxxxx
Xxx Xxxx, XX 00000

Re: Onyx Pharmaceuticals, Inc. — Lock-Up Agreement

Ladies and Gentlemen:

The undersigned understands that you, as representative (the “Representative”), propose to enter into (i) an Underwriting Agreement (the “Common Stock Underwriting Agreement”) on behalf of the several underwriters named in Schedule I to such agreement (the “Common Stock Underwriters”), with Onyx Pharmaceuticals, Inc., a Delaware corporation (the “Company”), providing for the offer and sale of the common stock of the Company, $0.001 par value per share (the “Stock”) and (ii) an Underwriting Agreement (the “Convertible Notes Underwriting Agreement”) on behalf of the several underwriters named in Schedule I to such agreement (the “Convertible Notes Underwriters”), with the Company, providing for the offer and sale of the Company’s Convertible Senior Notes due 2016 (the “Notes” and, together with the Stock, the “Securities”). The Notes will be convertible into shares of Stock.

The Common Stock Underwriting Agreement and the Convertible Notes Underwriting Agreement are collectively referred to as the “Underwriting Agreements” and the Common Stock Underwriters and the Convertible Notes Underwriters are collectively referred to as the “Underwriters.” Capitalized terms used herein and not otherwise defined shall have the meanings set forth in the Convertible Notes Underwriting Agreement.

In consideration of the agreement by the Underwriters to offer and sell the Securities, and of other good and valuable consideration the receipt and sufficiency of which is hereby acknowledged, the undersigned agrees that, during the period beginning on the date of the preliminary prospectus supplement relating to the offer and sale of the Securities (the “Effective Date”) and ending 60 days from the date of the Underwriting Agreements (the “Lock-up Termination Date,” the period between the Effective Date and the Lock-up Termination Date, is referred to herein as the “Lock-Up Period”), the undersigned will not offer, sell, contract to sell, pledge, grant any option to purchase, make any short sale or otherwise dispose of any shares of Stock of the Company, or any options or warrants to purchase any shares of Stock of the Company, or any securities convertible into, exchangeable for or that represent the right to receive shares of Stock of the Company, whether now owned or hereinafter acquired, owned directly by the undersigned (including holding as a custodian) or with respect to

C-1

which the undersigned has beneficial ownership (in each case, a “Transfer”) within the rules and regulations of the Securities and Exchange Commission (the “SEC”) (collectively, the “Undersigned’s Shares”). The foregoing restriction is expressly agreed to preclude the undersigned from engaging in any hedging or other transaction which is designed to or which reasonably could be expected to lead to or result in a sale or disposition of the Undersigned’s Shares even if such shares would be disposed of by someone other than the undersigned. Such prohibited hedging or other transactions would include without limitation any short sale or any purchase, sale or grant of any right (including without limitation any put or call option) with respect to any of the Undersigned’s Shares or with respect to any security that includes, relates to, or derives any significant part of its value from such shares.

Notwithstanding the foregoing, the following transfers of Stock shall be excluded from the definition of a Transfer: (i) transfers of Stock as a bona fide gift or gifts or by will or intestacy, provided that each donee, transferee or distributee thereof agrees to be bound in writing by the restrictions set forth herein, (ii) transfers of Stock to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for value, (iii) shares of Stock sold or tendered to the Company or withheld by the Company for tax withholding purposes in connection with the vesting of equity awards that are subject to a taxable event upon vesting, (iv) shares of Stock sold pursuant to a written contract, instruction or plan (a “Plan”) complying with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) or (v) transfers of Stock with the prior written consent of Xxxxxxx, Xxxxx & Co. on behalf of the Underwriters; provided, however, that in the case of clauses (i) and (ii), no party, including the undersigned, shall be required to, nor shall it voluntarily, file a report under the Exchange Act in connection with such transfer or distribution (other than a filing on Form 5 made after the expiration of the Lock-Up Period referred to above) or otherwise voluntarily effect any public filing, report or announcement of such transfer; and provided further, that in the case of clause (iv), such Plan has been entered into by the undersigned prior to the date of this Lock-Up Agreement and is not amended or modified during the Lock-Up Period.

For purposes of this Lock-Up Agreement, “immediate family” shall mean any relationship by blood, marriage or adoption, not more remote than first cousin. In addition, notwithstanding the foregoing, if the undersigned is a corporation, the corporation may transfer the capital stock of the Company to any wholly-owned subsidiary of such corporation; provided, however, that in any such case, it shall be a condition to the transfer that the transferee execute an agreement stating that the transferee is receiving and holding such capital stock subject to the provisions of this Lock-Up Agreement and there shall be no further transfer of such capital stock except in accordance with this Lock-Up Agreement, and provided further that any such transfer shall not involve a disposition for value. The undersigned now has, and, except as contemplated by clause (i), (ii), (iii), (iv) or (v) above, for the duration of this Lock-Up Agreement will have, good and marketable title to the Undersigned’s Shares, free and clear of all liens, encumbrances, and claims whatsoever.

In addition, the undersigned agrees that, without the prior written consent of Xxxxxxx, Sachs & Co. on behalf of the Underwriters, it will not, during the Lock-Up Period, make any demand for or exercise any right with respect to, the registration of any shares of Stock or any security convertible into or exercisable or exchangeable for Stock. The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of the Undersigned’s Shares except in compliance with the foregoing restrictions.

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The undersigned understands that the Company and the Underwriters are relying upon this Lock-Up Agreement in proceeding toward consummation of the offer and sale of the Securities. The undersigned also understands that, if neither of the Underwriting Agreements becomes effective by August 31, 2009, or if both of the Underwriting Agreements (other than the provisions thereof which survive termination) shall terminate or be terminated prior to payment for and delivery of the Securities to be sold thereunder, the undersigned shall be released from all obligations under this Lock-Up Agreement. The undersigned further understands that this Lock-Up Agreement is irrevocable and shall be binding upon the undersigned’s heirs, legal representatives, successors, and assigns.


	Very truly yours,

	Exact Name of Shareholder

	Authorized Signature

	Title

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Onyx Pharmaceuticals, Inc. 4.00% Convertible Senior Notes Due 2016 Underwriting Agreement

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