SEATTLE GENETICS, INC. Common Stock UNDERWRITING AGREEMENT dated March 29, 2006

Exhibit 1.1

SEATTLE GENETICS, INC.

Common Stock

UNDERWRITING AGREEMENT

dated March 29, 2006

Underwriting Agreement

March 29, ▇▇▇▇

▇▇▇▇ ▇▇ ▇▇▇▇▇▇▇ SECURITIES LLC

CIBC WORLD MARKETS CORP.

as Representatives of the several Underwriters

named in Schedule I

c/o Banc of America Securities LLC

▇ ▇▇▇▇ ▇▇^▇▇ ▇▇▇▇▇▇

▇▇▇ ▇▇▇▇ , ▇▇ ▇▇▇▇▇

Ladies and Gentlemen:

Introductory. Seattle Genetics, Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule A (the “Underwriters”) an aggregate of 7,300,000 shares (the “Shares”) of its Common Stock, par value $0.001 per share (the “Common Stock”). Banc of America Securities LLC (“BAS”) and CIBC World Markets Corp. (“CIBC”) have agreed to act as representatives of the several Underwriters (in such capacity, the “Representatives”) in connection with the offering and sale of the Shares.

To the extent there are no additional Underwriters listed on Schedule A other than you, the terms Representatives and Underwriters as used herein shall mean you, as Underwriters. The terms Representatives and Underwriters shall mean either the singular or plural as the context requires.

The Company hereby confirms its agreements with the Underwriters as follows:

SECTION 1. Representations and Warranties of the Company. The Company hereby represents and warrants to, and covenants with, each Underwriter as follows:

(a) The Company has prepared and filed with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-3 (File No. 333-120703), which contains a form of prospectus to be used in connection with the public offering and sale of the Shares. Such registration statement, as amended, including the financial statements, exhibits and schedules thereto, in the form in which it was declared effective by the Commission under the Securities Act of 1933 and the rules and regulations promulgated thereunder (collectively, the “Securities Act”), including any required information deemed to be a part thereof at the time of effectiveness pursuant to Rule 430B under the Securities Act or the Securities Exchange Act of 1934 and the rules and regulations promulgated thereunder (collectively, the “Exchange Act”), is called the “Registration Statement”. Any registration statement filed by the Company pursuant to Rule 462(b) under the Securities Act is called the “Rule 462(b) Registration Statement”, and from and after the date and time of filing of the Rule 462(b) Registration Statement the term

“Registration Statement” shall include the Rule 462(b) Registration Statement. Any preliminary prospectus supplement prospectus included in the Registration Statement and filed pursuant to Rule 424(b) after the date and time that this Agreement is executed and delivered by the parties hereto (the “Execution Time”) is hereinafter called a “Preliminary Prospectus.” The term “Prospectus” shall mean the preliminary prospectus and the final prospectus relating to the Shares that is first filed pursuant to Rule 424(b) after the Execution Time or, if no filing pursuant to Rule 424(b) is required, shall mean the preliminary prospectus and the form of final prospectus relating to the Shares included in the Registration Statement at the effective date. Any reference herein to the Registration Statement, any preliminary prospectus or the Prospectus shall be deemed to refer to and include the documents incorporated by reference therein. All references in this Agreement to the Registration Statement, the Rule 462(b) Registration Statement, a preliminary prospectus, the Prospectus, or any amendments or supplements to any of the foregoing, shall include any copy thereof filed with the Commission pursuant to its Electronic Data Gathering, Analysis and Retrieval System (“▇▇▇▇▇”).

(b) The Registration Statement has been declared effective by the Commission under the Securities Act. The Company has complied to the Commission’s satisfaction with all requests of the Commission for additional or supplemental information. No stop order suspending the effectiveness of the Registration Statement is in effect, the Commission has not issued any order or notice preventing or suspending the use of the Registration Statement, any preliminary prospectus or the Prospectus and no proceedings for such purpose have been instituted or are pending or, to the best knowledge of the Company, are contemplated or threatened by the Commission.

Each preliminary prospectus and the Prospectus when filed complied in all material respects with the Securities Act and the rules thereunder. Each of the Registration Statement and any post-effective amendment thereto, at the time it became effective and at the date hereof, complied and will comply in all material respects with the Securities Act and did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein not misleading. The Prospectus, as amended or supplemented, as of its date, at the date hereof, at the time of any filing pursuant to Rule 424(b), at the Closing Date (as defined herein), did not and will not contain any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The representations and warranties set forth in the two immediately preceding sentences do not apply to statements in or omissions from the Registration Statement or any post-effective amendment thereto, or the Prospectus, or any amendments or supplements thereto, made in reliance upon and in conformity with information relating to any Underwriter furnished to the Company in writing by the Representatives expressly for use therein, it being understood and agreed that the only such information furnished by the Representatives consists of the information described as such in Section 8 hereof.

(c) The documents incorporated by reference in 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 Securities Act or the Exchange Act, as applicable.

(d) The term “Disclosure Package” shall mean (i) the Preliminary Prospectus, (ii) the issuer free writing prospectuses as defined in Rule 433 of the Securities Act (each, an “Issuer Free Writing Prospectus”), if any, identified in Schedule B hereto, (iii) any other free writing prospectus that the parties hereto shall hereafter expressly agree in writing to treat as part of the Disclosure Package and (iv) the price at which the Shares will be sold to the public as provided on Schedule C. As of 9:30 am (Eastern time) on the date of execution and delivery of this Agreement (the “Applicable Time”), the Disclosure Package did not contain 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. The preceding sentence does not apply to statements in or omissions from the Disclosure Package based upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by or on behalf of any Underwriter consists of the information described as such in Section 8 hereof.

(e) (i) At the time of filing the Registration Statement and (ii) as of the date of the execution and delivery of this Agreement (with such date being used as the determination date for purposes of this clause (ii)), the Company was not and is not an Ineligible Issuer (as defined in Rule 405 of the Securities Act), without taking account of any determination by the Commission pursuant to Rule 405 of the Securities Act that it is not necessary that the Company be considered an Ineligible Issuer.

(f) Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the offering of Shares under this Agreement or until any earlier date that the Company notified or notifies the Representatives as described in the next sentence, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information contained in the Registration Statement. If at any time following issuance of an Issuer Free Writing Prospectus there occurred or occurs an event or development as a result of which such Issuer Free Writing Prospectus conflicted or would conflict with the information contained in the Registration Statement, the Company has promptly notified or will promptly notify the Representatives and has promptly amended or supplemented or will promptly amend or supplement, at its own expense, such Issuer Free Writing Prospectus to eliminate or correct such conflict. The foregoing two sentences do not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8 hereof.

(g) The financial statements of the Company (including all notes and schedules thereto) included or incorporated by reference in the Registration Statement, the Disclosure Package and the Prospectus present fairly the financial position of the Company as of the dates indicated and the results of its operations, stockholder’ equity and changes in their cash flows for the periods specified; said financial statements and related schedules and notes thereto, and the unaudited financial information filed with the Commission as part of the Registration Statement, have been prepared in conformity with generally accepted accounting principles, consistently applied throughout the periods involved, and the supporting schedules included in the Registration Statement present fairly the information required to be stated therein; and the pro forma financial

information, and the related notes thereto, included in the Registration Statement, the Disclosure Package and the Prospectus has been prepared in accordance with the applicable requirements of the Securities Act and the Exchange Act, as applicable, and is based upon good faith estimates and assumptions believed by the Company to be reasonable.

(h) Except as otherwise disclosed in the Disclosure Package and the Prospectus, subsequent to the respective dates as of which information is given in the Disclosure Package, there has not occurred any material adverse change, or any development involving a prospective material adverse change, in the condition, financial or otherwise, or in the earnings, business, operations or prospects of the Company (a “Material Adverse Change”).

(i) PricewaterhouseCoopers LLP who have audited certain financial statements of the Company, are an independent registered public accounting firm as required by the Securities Act.

(j) The Company is 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 Registration Statement, the Disclosure Package and the Prospectus, and has been duly qualified as a foreign corporation for the transaction of business and is in good standing or, where applicable, validly existing under the laws of each other jurisdiction in which it owns or leases properties, or conducts any business, so as to require such qualification, other than where the failure to be so qualified, in good standing or validly existing would not have, individually or in the aggregate, a material adverse effect on the general affairs, business, prospects, management, financial position, earnings, properties, stockholders’ equity or results of operations of the Company whether or not arising from transactions in the ordinary course of business, of the Company (a “Material Adverse Effect”).

(k) The Company has all requisite corporate power and authority, and all necessary authorizations, approvals, consents, orders, licenses, certificates and permits of and from all governmental or regulatory bodies or any other person or entity (collectively, the “Permits”), to own, lease and license its assets and properties and conduct its business, all of which are valid and in full force and effect, except where the lack of such Permits, individually or in the aggregate, would not have a Material Adverse Effect. The Company has fulfilled and performed in all material respects all of its material obligations with respect to such Permits and no event has occurred that allows, or after notice or lapse of time would allow, revocation or termination thereof or results in any other material impairment of the rights of the Company thereunder. Except as may be required under the Securities Act and state and foreign Blue Sky laws, no other Permits are required to enter into, deliver and perform this Agreement and to issue and sell the Shares. All of the descriptions in the Registration Statement, the Disclosure Package, and the Prospectus of the legal and governmental procedures and requirements of the United States Food and Drug Administration (the “FDA”) or any foreign, state or local governmental body exercising comparable authority are accurate in all material respects.

(l) Except as described in the Registration Statement, the Disclosure Package, and the Prospectus, the Company owns, is licensed to use or otherwise possesses adequate rights to use the patents, patent rights, licenses, inventions, trademarks, service marks, trade names,

copyrights and know-how, including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems, processes or procedures (collectively, the “Intangibles”), reasonably necessary to carry on the business conducted by it, except to the extent that the failure to own, be licensed to use or otherwise possess adequate rights to use such Intangibles would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; the Company has not received any notice of infringement of or conflict with, and the Company has no knowledge of any infringement of or conflict with, asserted rights of others with respect to its Intangibles which would, individually or in the aggregate, reasonably be expected to result in a Material Adverse Effect; the discoveries, inventions, products or processes of the Company referred to in the Registration Statement, the Disclosure Package, and the Prospectus do not, to the knowledge of the Company, infringe or conflict with any right or patent of any third party, or any discovery, invention, product or process which is the subject of a patent application filed by any third party which patent application has been published or is otherwise known to the Company which could, individually or in the aggregate, reasonably be expected to result in a Material Adverse Effect; except as set forth in the Registration Statement, the Disclosure Package, and the Prospectus, the Company is not obligated to pay a royalty, grant a license or provide other consideration to any third party in connection with its patents, patent rights, licenses, inventions, trademarks, service marks, trade names, copyrights and know-how which could, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; and no third party, including any academic or governmental organization, possesses rights to the Intangibles which, if exercised, could reasonably be expected to have a Material Adverse Effect.

(m) The Company has good and marketable title in fee simple to all items of real property and good and marketable title to all personal property owned by it, in each case free and clear of all liens, encumbrances, claims, security interests and defects except such as are described or referred to in the Registration Statement, the Disclosure Package, and the Prospectus or such as do not materially affect the value of such property and do not interfere with the use made or proposed to be made of such property by the Company; and any real property and buildings held under lease by the Company are held by them under valid, existing and enforceable leases with such exceptions as are not material and do not interfere with the use made or proposed to be made of such property and buildings by the Company.

(n) Other than as set forth in the Registration Statement, the Disclosure Package, and the Prospectus, there are no legal or governmental investigations, actions, suits or proceedings pending or, to the knowledge of the Company, threatened against or affecting the Company or any of its properties or to which the Company is or may be a party or to which any property of the Company is or may be the subject which, if determined adversely to the Company, could, individually or in the aggregate, have, or reasonably be expected to have, a Material Adverse Effect, and, to the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others.

(o) There are no statutes, regulations or legal or governmental investigations, actions, suits or proceedings pending or, to the knowledge of the Company, threatened that are required to be described in the Registration Statement, the Disclosure Package, or Prospectus or to be filed as exhibits to the Registration Statement, as the case may be, that are not described or filed as required

(p) Since the respective dates as of which information is given in the Registration Statement, the Disclosure Package, and the Prospectus, the studies, tests and preclinical and clinical trials conducted by or on behalf of the Company that are described in the Registration Statement, the Disclosure Package, and the Prospectus were and, if still pending, are being conducted in accordance with experimental protocols, procedures and controls pursuant to, where applicable, accepted professional scientific standards; the descriptions of the results of such studies, tests and trials contained in the Registration Statement, the Disclosure Package, and the Prospectus are accurate and complete summaries of such studies, tests and trials and do not omit any material facts necessary to make the statements therein not misleading; and the Company has not received any notices or correspondence from the FDA or any foreign, state or local governmental body exercising comparable authority requiring the termination, suspension or material modification of any studies, tests or preclinical or clinical trials conducted by or on behalf of the Company which termination, suspension or material modification would reasonably be expected to have a Material Adverse Effect.

(q) There is no document, contract or other agreement required to be described in the Registration Statement, the Disclosure Package, or Prospectus or to be filed as an exhibit to the Registration Statement which is not described or filed as required by the Securities Act or Rules. Each description of a contract, document or other agreement in the Registration Statement, the Disclosure Package, and the Prospectus accurately reflects in all material respects the terms of the underlying contract, document or other agreement. Each contract, document or other agreement described in the Registration Statement, the Disclosure Package, and Prospectus or listed in the exhibits to the Registration Statement or incorporated by reference is in full force and effect and is valid and enforceable by and against the Company in accordance with its terms, other than agreements which have by their terms expired or which the Company has terminated after determining that terminating such agreements would not have a Material Adverse Effect. Neither the Company nor to the Company’s knowledge, any other party is in default in the observance or performance of any term or obligation to be performed by it under any such agreement, and no event has occurred which with notice or lapse of time or both would constitute such a default, in any such case which default or event, individually or in the aggregate, would have a Material Adverse Effect.

(r) The Company is not, and with the giving of notice or lapse of time or both would not be, in violation of or in default under (i) its certificate of incorporation or by-laws or (ii) any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which it or any of its properties is bound, except with respect to clause (ii) for violations and defaults which would not, individually or in the aggregate, have a Material Adverse Effect.

(s) This Agreement has been duly authorized, executed and delivered by the Company.

(t) The issuance and sale of the Shares and the performance by the Company of its obligations under this Agreement and the consummation of the transactions contemplated herein and in the Disclosure Package and Prospectus will not conflict with, result in a breach of or violate any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other material 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 any such action result in any violation of the provisions of the certificate of incorporation or by-laws of the Company or any applicable law or statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of its respective properties; and no consent, approval, authorization, order, license, registration or qualification of or with any such court or governmental agency or body is required for the issuance and sale of the Shares or the consummation by the Company of the transactions contemplated by this Agreement and the Disclosure Package and Prospectus, except such consents, approvals, authorizations, orders, licenses, registrations or qualifications as have been obtained or made under the Securities Act and as may be required under state securities or blue sky laws in connection with the purchase and distribution of the Shares by the Underwriters.

(u) The Company has authorized and outstanding capital stock as set forth under the caption “Description of Capital Stock” in the Disclosure Package and Prospectus as of the dates set forth therein and such authorized capital stock conforms in all material respects to the description thereof set forth in the Registration Statement, the Disclosure Package, and the Prospectus, and all of the outstanding shares of capital stock of the Company have been duly authorized and validly issued, are fully paid and non-assessable and are not subject to any pre-emptive or similar rights; and, except as described in or expressly contemplated by the Registration Statement, the Disclosure Package, and the Prospectus, as of the dates set forth therein, there are no outstanding rights (including, without limitation, pre-emptive rights), warrants or options to acquire, or instruments convertible into or exchangeable for, any shares of capital stock or other equity interest in the Company, or any contract, commitment, agreement, understanding or arrangement of any kind relating to the issuance of any capital stock of the Company, any such convertible or exchangeable securities or any such rights, warrants or options; the Company has no subsidiaries and does not own any shares of capital stock or other equity interests or any instruments convertible into or exchangeable for, any shares of capital stock or other equity interest, or any contract, commitment, agreement, understanding or arrangement of any kind relating to the issuance of any capital stock, any such convertible or exchangeable securities or any such rights, warrants or options of any third party, except for such shares of capital stock purchased pursuant to the Company’s routine investment program and the Company’s right to repurchase at cost certain shares subject to vesting that were acquired by holders upon exercise of stock options.

(v) Each director and executive officer of the Company and each stockholder of the Company listed on Exhibit E has delivered to the Representatives his written lock-up agreement substantially in the form attached to this Agreement as Exhibit D hereto (the “Lock-Up Agreement”) or in such other form as agreed with Representatives.

(w) All necessary corporate action has been duly and validly taken by the Company and to authorize the execution, delivery and performance of this Agreement and the issuance and sale of the Shares by the Company. This Agreement has been duly and validly authorized, executed and delivered by the Company and constitute and will constitute the legal, valid and binding obligation of the Company enforceable against the Company in accordance with its terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, reorganization, moratorium or other similar laws affecting the enforcement of creditors’ rights generally and by general equitable principles.

(x) There are no existing or, to the knowledge of the Company, threatened labor disputes with the employees of the Company which would reasonably be expected to have a Material Adverse Effect.

(y) No relationship, direct or indirect, exists between or among the Company, on the one hand, and the directors, officers, stockholders, customers or suppliers of the Company, on the other hand, which is required by the Securities Act to be described in the Registration Statement, the Disclosure Package, and the Prospectus which is not so described.

(z) The Company has not taken nor will it take, directly or indirectly, any action designed to, or which might be reasonably expected to, cause or result in, or which has constituted or which might reasonably be expected to constitute, the stabilization or manipulation of the price of the Common Stock or any security of the Company to facilitate the sale or resale of any of the Shares.

(aa) The statistical and market-related data included in the Registration Statement, the Disclosure Package, and the Prospectus are based on or derived from sources which are believed by the Company to be reliable.

(bb) The Company has filed all Federal, state, local and foreign tax returns which are required to be filed through the date hereof, which returns are true and correct in all material respects or has received timely extensions thereof, and has paid all taxes shown on such returns and all assessments received by it to the extent that the same are material and have become due. There are no tax audits or investigations pending, which if adversely determined would have a Material Adverse Effect; nor are there any material proposed additional tax assessments against the Company.

(cc) The Shares have been duly authorized for quotation on the National Association of Securities Dealers Automated Quotation (“Nasdaq”) National Market System. The Shares have been duly authorized, and, when issued and delivered to and paid for by the Underwriters in accordance with the terms of this Agreement, will be duly issued and will be fully paid and non-assessable and will conform to the description thereof set forth in the Registration Statement, the Disclosure Package, and the Prospectus; and the issuance of the Shares is not subject to any preemptive or similar rights.

(dd) The Company has taken no action designed to, or likely to have the effect of, terminating the registration of the Common Stock under the Exchange Act or the quotation of the Common Stock on the Nasdaq National Market, nor has the Company received any notification that the Commission or the Nasdaq National Market is contemplating terminating such registration or quotation.

(ee) The books, records and accounts of the Company accurately and fairly reflect, in reasonable detail, the transactions in, and dispositions of, the assets of, and the results of operations of, the Company. The Company maintains a system of internal accounting controls sufficient to provide reasonable assurances that (i) transactions are executed in accordance with management’s general or specific authorizations, (ii) transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting

principles and to maintain asset accountability, (iii) access to assets is permitted only in accordance with management’s general or specific authorization and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences; the chief executive officer and the chief financial officer of the Company have made all certifications required by the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002 (the “▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act”) and any related rules and regulations promulgated by the Commission, and the statements contained in any such certification are complete and correct; the Company is otherwise in compliance in all material respects with all applicable effective provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act and is actively taking steps to ensure that it will be in compliance with other applicable provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act upon the effectiveness of such provisions.

(ff) The Company carries, or is covered by, insurance in such amounts and covering such risks as is adequate for the conduct of its business and the value of its properties and as is customary for companies engaged in similar businesses in similar industries.

(gg) The Company has established and maintains “disclosure controls and procedures” (as such term is defined in Rule 13a-14 under the Exchange Act, which (i) are designed to ensure that material information relating to the Company is made known to the Company’s principal executive officer and its principal financial officer by others within those entities, particularly during the periods in which the periodic reports required under the Exchange Act are being prepared; and (ii) provide for the periodic evaluation of the effectiveness of such disclosure controls and procedures as of the end of the period covered by the Company’s most recent annual or quarterly report filed with the Commission.

(hh) Based on the evaluation of its disclosure controls and procedures, the Company is not aware of (i) any significant deficiency in the design or operation of internal controls which could adversely affect the Company’s ability to record, process, summarize and report financial data or any material weaknesses in internal controls; or (ii) any fraud, whether or not material, that involves management or other employees who have a significant role in the Company’s internal controls.

(ii) Since the date of the most recent evaluation of such disclosure controls and procedures, there have been no changes that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting, including any corrective actions with regard to significant deficiencies and material weaknesses.

(jj) Except as described in the Disclosure Package and the Prospectus, there are no material off-balance sheet arrangements (as defined in Item 303 of Regulation S-K), or any other relationships with unconsolidated entities or other persons, that may 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.

(kk) Since May 6, 2003 (i) all audit and non-audit services performed by PricewaterhouseCoopers LLP have been preapproved in accordance with the requirements set forth in Section 10A of the Exchange Act and (ii) PricewaterhouseCoopers LLP has not engaged

and as of the date hereof is not engaging in any “prohibited activities” (as defined in Section 10A of the Exchange Act) on behalf of the Company.

(ll) The Company’s Board of Directors has validly appointed an audit committee whose composition satisfies the requirements of Rule 4350(d)(2) of the Rules of the National Association of Securities Dealers, Inc. (the “NASD Rules”) and the Board of Directors and/or the audit committee has adopted a charter that satisfies the requirements of Rule 4350(d)(1) of the NASD Rules. The audit committee has reviewed the adequacy of its charter since January 1, 2003. Neither the Board of Directors nor the audit committee has been informed of (1) any significant deficiencies in the design or operation of the Company’s internal controls which could adversely affect the Company’s ability to record, process, summarize and report financial data or any material weakness in the Company’s internal controls; or (2) any fraud, whether or not material, that involves management or other employees of the Company who have a significant role in the Company’s internal controls.

(mm) Each approval, consent, order, authorization, designation, declaration or filing of, by or with any regulatory, administrative or other governmental body necessary in connection with the execution and delivery by the Company of this Agreement and the consummation of the transactions herein contemplated required to be obtained or performed by the Company (except such additional steps as may be required by the National Association of Securities Dealers, Inc. (the “NASD”) or may be necessary to qualify the Shares for public offering by the Underwriters under the state securities or Blue Sky laws) has been obtained or made and is in full force and effect.

(nn) There are no affiliations with the NASD among the Company’s officers, directors or, to the best of the knowledge of the Company, any five percent or greater stockholder of the Company, except as set forth in the Registration Statement or otherwise disclosed in writing to the Representatives.

(oo) 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 or hazardous or toxic substances or wastes, pollutants or contaminants (collectively, “Environmental Laws”), (ii) has received all permits, licenses or other approvals required of it under applicable Environmental Laws to conduct its businesses 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 or other approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(pp) The Company is not and, after giving effect to the offering and the sale of the Shares and the application of the proceeds thereof, will not be an “investment company” or an entity “controlled” by and “investment company” as such terms are defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”).

(qq) Neither the Company, its directors, officers or employees nor, to the Company’s knowledge, any other person associated with or acting on behalf of the Company has directly or indirectly, while acting on behalf of the Company (i) used any corporate funds for unlawful

contributions, gifts, entertainment or other unlawful expenses relating to political activity; (ii) made any unlawful payment to foreign or domestic government officials or employees or to foreign or domestic political parties or campaigns from corporate funds; (iii) violated any provision of the Foreign Corrupt Practices Act of 1977, as amended; or (iv) made any other unlawful payment.

(rr) Except as described in the Disclosure Package and Prospectus or in the documents incorporated by reference into the Disclosure Package or Prospectus, the Company has not sold or issued any shares of Common Stock during the six-month period preceding the date of the Prospectus, including any sales pursuant to Rule 144A under, or Regulations D or S of, the Securities Act, other than shares issued pursuant to employee benefit plans, qualified stock options plans or other employee compensation plans or pursuant to outstanding options, rights or warrants.

(ss) Each employee benefit plan, within the meaning of Section 3(3) of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), that is maintained, administered or contributed to by the Company or any of its affiliates for employees or former employees of the Company and its affiliates has been maintained in material compliance with its terms and the requirements of any applicable statutes, orders, rules and regulations, including but not limited to ERISA and the Internal Revenue Code of 1986, as amended (“Code”); no prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code, has occurred with respect to any such plan excluding transactions effected pursuant to a statutory or administrative exemption; for each such plan which is subject to the funding rules of Section 412 of the Code or Section 302 of ERISA, no “accumulated funding deficiency,” as defined in Section 412 of the Code, has been incurred, whether or not waived, and the fair market value of the assets of each such plan (excluding for these purposes accrued but unpaid contributions) exceed the present value of all benefits accrued under such plan determined using reasonable actuarial assumptions.

(tt) Each of the Company, its directors and officers has not distributed and will not distribute prior to the later of (i) the Shares Closing Date and (ii) completion of the distribution of the Shares, any offering material in connection with the offering and sale of the Shares other than the Disclosure Package, the Prospectus, the Registration Statement and other materials, if any, permitted by the Securities Act.

(uu) No person has the right to require the Company to register any securities for offering and sale under the Securities Act by reason of the filing of the Registration Statement with the Commission or by reason of the issuance and sale of the Shares, except for rights which have been waived.

Any certificate signed by an officer of the Company and delivered to the Representatives or to counsel for the Underwriters shall be deemed to be a representation and warranty by the Company to each Underwriter as to the matters set forth therein.

SECTION 2. Purchase, Sale and Delivery of the Shares.

(a) The Shares. The Company agrees to issue and sell to the several Underwriters the Shares upon the terms herein set forth. On the basis of the representations, warranties and agreements herein contained, and upon the terms but subject to the conditions herein set forth, the Underwriters agree, severally and not jointly, to purchase from the Company the respective number of Shares set forth opposite their names on Schedule A. The purchase price per Share to be paid by the several Underwriters to the Company shall be $5.13 per share.

(b) The Closing Date. Delivery of certificates for the Shares to be purchased by the Underwriters and payment therefor shall be made at the offices of Cooley Godward LLP, ▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇., ▇▇▇▇ ▇▇▇▇ ▇▇ ▇▇▇▇▇ (or such other place as may be agreed to by the Company and the Representatives) at 9:00 a.m. New York time, on April 3, 2006, or such other time and date not later than 1:30 p.m. New York time, on April 7, 2006, as the Representatives shall designate by notice to the Company (the time and date of such closing are called the “Closing Date”).

(c) Public Offering of the Shares. The Representatives hereby advise the Company that the Underwriters intend to offer for sale to the public, as described in the Prospectus, their respective portions of the Shares as soon after this Agreement has been executed and the Registration Statement has been declared effective as the Representatives, in their sole judgment, have determined is advisable and practicable.

(d) Payment for the Shares. Payment for the Shares shall be made at the Closing Date by wire transfer of immediately available funds to the order of the Company.

It is understood that the Representatives have been authorized, for their own account and the accounts of the several Underwriters, to accept delivery of and receipt for, and make payment of the purchase price for, the Shares the Underwriters have agreed to purchase. BAS, individually and not as the Representative of the Underwriters, may (but shall not be obligated to) make payment for any Shares to be purchased by any Underwriter whose funds shall not have been received by the Representatives by the Closing Date, as the case may be, for the account of such Underwriter, but any such payment shall not relieve such Underwriter from any of its obligations under this Agreement.

(e) Delivery of the Shares. Delivery of the Shares shall be made through the facilities of The Depository Trust Company unless the Representatives shall otherwise instruct. Time shall be of the essence, and delivery at the time and place specified in this Agreement is a further condition to the obligations of the Underwriters.

(f) Delivery of Prospectus to the Underwriters. Not later than 10:00 a.m. on the second business day following the date the Shares are first released by the Underwriters for sale to the public, the Company shall deliver or cause to be delivered, copies of the Prospectus in such quantities and at such places as the Representatives shall request.

SECTION 3. Covenants of the Company.

A. Covenants of the Company. The Company covenants and agrees with each Underwriter as follows:

(a) Representatives’ Review of Proposed Amendments and Supplements. During the period beginning on the Applicable Time and ending on the later of the Closing Date or such date, as in the opinion of counsel for the Underwriters, the Prospectus is no longer required by law to be delivered in connection with sales by an Underwriter or dealer, including in circumstances where such requirement may be satisfied pursuant to Rule 172 (the “Prospectus Delivery Period”), prior to amending or supplementing the Registration Statement, the Disclosure Package or the Prospectus, subject to Section 3(A)(e), the Company shall furnish to the Representatives for review a copy of each such proposed amendment or supplement, and the Company shall not file or use any such proposed amendment or supplement to which the Representatives reasonably object.

(b) Securities Act Compliance. After the date of this Agreement, the Company shall promptly advise the Representatives in writing (i) when the Registration Statement, if not effective at the Execution Time, shall have become effective, (ii) of the receipt of any comments of, or requests for additional or supplemental information from, the Commission, (iii) of the time and date of any filing of any post-effective amendment to the Registration Statement or any amendment or supplement to any preliminary prospectus or the Prospectus, (iv) of the time and date that any post-effective amendment to the Registration Statement becomes effective and (v) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement or of any order or notice preventing or suspending the use of the Registration Statement, any preliminary prospectus or the Prospectus, or of any proceedings to remove, suspend or terminate from listing or quotation the Common Stock from any securities exchange upon which it is listed for trading or included or designated for quotation, or of the threatening or initiation of any proceedings for any of such purposes. The Company shall use its best efforts to prevent the issuance of any such stop order or notice of prevention or suspension of such use. If the Commission shall enter any such stop order or issue any such notice at any time, the Company will use its best efforts to obtain the lifting or reversal of such order or notice at the earliest possible moment, or, subject to Section 3(A)(a), will file an amendment to the Registration Statement or will file a new registration statement and use its best efforts to have such amendment or new registration statement declared effective as soon as practicable. Additionally, the Company agrees that it shall comply with the provisions of Rules 424(b) and 430B, as applicable, under the Securities Act, including with respect to the timely filing of documents thereunder, and will use its reasonable efforts to confirm that any filings made by the Company under such Rule 424(b) were received in a timely manner by the Commission.

(c) Exchange Act Compliance. During the Prospectus Delivery Period, the Company will file all documents required to be filed with the Commission pursuant to Section 13, 14 or 15 of the Exchange Act in the manner and within the time periods required by the Exchange Act.

(d) Amendments and Supplements to the Registration Statement, Disclosure Package and Prospectus and Other Securities Act Matters. If, during the Prospectus Delivery Period, any event or development shall occur or condition exist as a result of which the Disclosure Package or the Prospectus as then amended or supplemented would 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 or then prevailing, as the case may be, not misleading, or if it shall be necessary to amend or supplement the Disclosure Package or the Prospectus, or to file under the Exchange Act any document incorporated by reference in the

Disclosure Package or the Prospectus, in order to make the statements therein, in the light of the circumstances under which they were made or then prevailing, as the case may be, not misleading, or if in the opinion of the Representatives it is otherwise necessary or advisable to amend or supplement the Registration Statement, the Disclosure Package or the Prospectus, or to file under the Exchange Act any document incorporated by reference in the Disclosure Package or the Prospectus , or to file a new registration statement containing the Prospectus, in order to comply with law, including in connection with the delivery of the Prospectus, the Company agrees to (i) notify the Representatives of any such event or condition and (ii) promptly prepare (subject to Section 3(A)(a) and 3(A)(e) hereof), file with the Commission (and use its best efforts to have any amendment to the Registration Statement or any new registration statement to be declared effective) and furnish at its own expense to the Underwriters and to dealers, amendments or supplements to the Registration Statement, the Disclosure Package or the Prospectus, or any new registration statement, necessary in order to make the statements in the Disclosure Package or the Prospectus as so amended or supplemented, in the light of the circumstances under which they were made or then prevailing, as the case may be, not misleading or so that the Registration Statement, the Disclosure Package or the Prospectus, as amended or supplemented, will comply with law.

(e) Permitted Free Writing Prospectuses. The Company represents that it has not made, and agrees that, unless it obtains the prior written consent of the Representatives, it will not make, any offer relating to the Shares that constitutes or would constitute an Issuer Free Writing Prospectus or that otherwise constitutes or would constitute a “free writing prospectus” (as defined in Rule 405 of the Securities Act) or a portion thereof required to be filed by the Company with the Commission or retained by the Company under Rule 433 of the Securities Act; provided that the prior written consent of the Representatives hereto shall be deemed to have been given in respect of the Free Writing Prospectuses included in Schedule B hereto and any electronic road show. Any such free writing prospectus consented to by the Representatives is hereinafter referred to as a “Permitted Free Writing Prospectus”. The Company agrees that (i) it has treated and will treat, as the case may be, each Permitted Free Writing Prospectus as an Issuer Free Writing Prospectus, and (ii) has complied and will comply, as the case may be, with the requirements of Rules 164 and 433 of the Securities Act applicable to any Permitted Free Writing Prospectus, including in respect of timely filing with the Commission, legending and record keeping.

(f) Copies of any Amendments and Supplements to the Prospectus. The Company agrees to furnish the Representatives, without charge, during the Prospectus Delivery Period, as many copies of the Prospectus and any amendments and supplements thereto (including any documents incorporated or deemed incorporated by reference therein) and the Disclosure Package as the Representatives may request.

(g) Copies of the Registration Statement and the Prospectus. The Company will furnish to the Representatives and counsel for the Underwriters signed copies of the Registration Statement (including exhibits thereto) and, so long as delivery of a prospectus by an Underwriter or dealer may be required by the Act, as many copies of each preliminary prospectus, the Prospectus and any supplement thereto and the Disclosure Package as the Representatives may reasonably request.

(h) Blue Sky Compliance. The Company shall cooperate with the Representatives and counsel for the Underwriters to qualify or register the Shares for sale under (or obtain exemptions from the application of) the state securities or blue sky laws or Canadian provincial Securities laws of those jurisdictions designated by the Representatives, shall comply with such laws and shall continue such qualifications, registrations and exemptions in effect so long as required for the distribution of the Shares. The Company shall not be required to qualify as a foreign corporation or to take any action that would subject it to general service of process in any such jurisdiction where it is not presently qualified or where it would be subject to taxation as a foreign corporation, other than those arising out of the offering or sale of the Shares in any jurisdiction where it is not now so subject. The Company will advise the Representatives promptly of the suspension of the qualification or registration of (or any such exemption relating to) the Shares for offering, sale or trading in any jurisdiction or any initiation or threat of any proceeding for any such purpose, and in the event of the issuance of any order suspending such qualification, registration or exemption, the Company shall use its best efforts to obtain the withdrawal thereof at the earliest possible moment.

(i) Use of Proceeds. The Company shall apply the net proceeds from the sale of the Shares sold by it in the manner described under the caption “Use of Proceeds” in the Disclosure Package and the Prospectus.

(j) Transfer Agent. The Company shall engage and maintain, at its expense, a registrar and transfer agent for the Common Stock.

(k) Earnings Statement. As soon as practicable, the Company will make generally available to its security holders and to the Representatives an earnings statement (which need not be audited) covering the twelve-month period that satisfies the provisions of Section 11(a) of the Securities Act and Rule 158 under the Securities Act.

(l) Periodic Reporting Obligations. During the Prospectus Delivery Period the Company shall file, on a timely basis, with the Commission and the Nasdaq Stock Market, Inc. all reports and documents required to be filed under the Exchange Act. Additionally, the Company shall report the use of proceeds from the issuance of the Shares as may be required under Rule 463 under the Securities Act.

(m) Quotation. The Company will use its best efforts to quote, subject to notice of issuance, the Shares on the Nasdaq Stock Market, Inc.

(n) Agreement Not to Offer or Sell Additional Shares. During the period commencing on the date hereof and ending on the 90th day following the date of the Prospectus, the Company will not, without the prior written consent of BAS and CIBC (which consent may be withheld at the sole discretion of BAS and CIBC), directly or indirectly, sell, offer, contract or grant any option to sell, pledge, transfer or establish an open “put equivalent position” or liquidate or decrease a “call equivalent position” within the meaning of Rule 16a-1(h) under the Exchange Act, or otherwise dispose of or transfer (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition of), or announce the offering of, or file any registration statement under the Securities Act in respect of (other than on Form S-8 or on any successor form), any shares of Common Stock, options or warrants to acquire shares of the

Common Stock or securities exchangeable or exercisable for or convertible into shares of Common Stock (other than as contemplated by this Agreement with respect to the Shares); provided, however, that the Company may issue shares of its Common Stock or options to purchase its Common Stock, or Common Stock upon exercise of options, pursuant to any stock option, stock bonus or other stock plan or arrangement described in the Registration Statement or Prospectus and may issue up to 1,129,015 shares of its Common Stock pursuant to the Stock Purchase Agreement of even date herewith among the Company and investment funds affiliated with ▇▇▇▇▇ Brothers Investments.

(o) Compliance with ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act. The Company will comply with all applicable securities and other laws, rules and regulations, including, without limitation, the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act, and use its best efforts to cause the Company’s directors and officers, in their capacities as such, to comply with such laws, rules and regulations, including, without limitation, the provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act.

(p) Future Reports to Stockholders. To furnish to its stockholders as soon as practicable after the end of each fiscal year an annual report (including a balance sheet and statements of income, stockholders’ equity and cash flows of the Company and its consolidated subsidiaries certified by an independent registered public accounting firm) and, as soon as practicable after the end of each of the first three quarters of each fiscal year (beginning with the fiscal quarter ending after the effective date of the Registration Statement), to make available to its stockholders consolidated summary financial information of the Company and its subsidiaries for such quarter in reasonable detail.

(q) Future Reports to the Representatives. During the period of five years hereafter the Company will furnish to the Representatives at ▇ ▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇: Legal Department: (i) as soon as practicable after the end of each fiscal year, copies of the Annual Report of the Company containing the balance sheet of the Company as of the close of such fiscal year and statements of income, stockholders’ equity and cash flows for the year then ended and the opinion thereon of the Company’s independent registered public accounting firm; (ii) as soon as practicable after the filing thereof, copies of each proxy statement, Annual Report on Form 10-K, Quarterly Report on Form 10-Q, Current Report on Form 8-K or other report filed by the Company with the Commission, the NASD or any securities exchange; and (iii) as soon as available, copies of any report or communication of the Company mailed generally to holders of its capital stock.

(r) Investment Limitation. The Company shall not invest, or otherwise use the proceeds received by the Company from its sale of the Shares in such a manner as would require the Company or any of its subsidiaries to register as an investment company under the Investment Company Act.

(s) No Manipulation of Price. The Company will not take, directly or indirectly, any action designed to cause or result in, or that has constituted or might reasonably be expected to constitute, under the Exchange Act or otherwise, the stabilization or manipulation of the price of any securities of the Company to facilitate the sale or resale of the Shares.

SECTION 4. Payment of Expenses. The Company agrees to pay all costs, fees and expenses incurred in connection with the performance of its obligations hereunder and in connection with the transactions contemplated hereby, including without limitation (i) all expenses incident to the issuance and delivery of the Shares (including all printing and engraving costs), (ii) all fees and expenses of the registrar and transfer agent of the Common Stock, (iii) all necessary issue, transfer and other stamp taxes in connection with the issuance and sale of the Shares to the Underwriters, (iv) all fees and expenses of the Company’s counsel, independent registered public accounting firm and other advisors, (v) all costs and expenses incurred in connection with the preparation, printing, filing, shipping and distribution of the Registration Statement (including financial statements, exhibits, schedules, consents and certificates of experts), each Issuer Free Writing Prospectus, each preliminary prospectus and the Prospectus, and all amendments and supplements thereto, and this Agreement, (vi) all filing fees, attorneys’ fees and expenses incurred by the Company or the Underwriters in connection with qualifying or registering (or obtaining exemptions from the qualification or registration of) all or any part of the Shares for offer and sale under the state securities or blue sky laws or the provincial securities laws of Canada, and, if requested by the Representatives, preparing and printing a “Blue Sky Survey” or memorandum, and any supplements thereto, advising the Underwriters of such qualifications, registrations and exemptions, (vii) the filing fees incident to, and the reasonable fees and expenses of counsel for the Underwriters in connection with, the NASD’s review and approval of the Underwriters’ participation in the offering and distribution of the Shares, (viii) the fees and expenses associated with quotation of the Shares on the Nasdaq Stock Market, Inc., and (ix) all other fees, costs and expenses referred to in Item 14 of Part II of the Registration Statement. Except as provided in this Section 4, Section 6, Section 8 and Section 9 hereof, the Underwriters shall pay their own expenses, including the fees and disbursements of their counsel. The Company shall not be required to pay any costs, fees or compensation that would be deemed to be a “Prohibited Arrangement” as described in NASD Rule 2710(f)(2)(D).

SECTION 5. Conditions of the Obligations of the Underwriters. The obligations of the several Underwriters to purchase and pay for the Shares as provided herein on the Closing Date and shall be subject to the accuracy of the representations and warranties on the part of the Company set forth in Section 1 hereof as of the date hereof and as of the Closing Date as though then made and to the accuracy of the statements of the Company made in any certificates pursuant to the provisions hereof, to the timely performance by the Company of its covenants and other obligations hereunder, and to each of the following additional conditions:

(a) Accountants’ Comfort Letter. On the date hereof, the Representatives shall have received from PricewaterhouseCoopers LLP, independent registered public accounting firm for the Company, a letter dated the date hereof addressed to the Underwriters, in form and substance satisfactory to the Representatives.

(b) Compliance with Registration Requirements; No Stop Order; No Objection from NASD. For the period from and after effectiveness of this Agreement and prior to the Closing Date:

(i) the Company shall have filed the Prospectus with the Commission (including the information required by Rule 430B under the Securities Act) in the manner and within the time period required by Rule 424(b) under the Securities Act; or the Company

shall have filed a post-effective amendment to the Registration Statement containing the information required by such Rule 430B, and such post-effective amendment shall have become effective;

(ii) all material required to be filed by the Company pursuant to Rule 433(d) under the Securities Act shall have been filed with the Commission within the applicable time periods prescribed for such filings under such Rule 433;

(iii) no stop order suspending the effectiveness of the Registration Statement, or any post-effective amendment to the Registration Statement, shall be in effect and no proceedings for such purpose shall have been instituted or threatened by the Commission; and

(iv) the NASD shall have raised no objection to the fairness and reasonableness of the underwriting terms and arrangements.

(c) No Material Adverse Change or Ratings Agency Change. For the period from and after the date of this Agreement and prior to the Closing Date:

(i) in the judgment of the Representatives there shall not have occurred any Material Adverse Change;

(ii) there shall not have been any change or decrease specified in the letter or letters referred to in paragraph (a) of this Section 5 which is, in the sole judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the offering or delivery of the Shares as contemplated by the Registration Statement and the Prospectus; and

(iii) there shall not have occurred any downgrading, nor shall any notice have been given of any intended or potential downgrading or of any review for a possible change that does not indicate the direction of the possible change, in the rating accorded any securities of the Company by any “nationally recognized statistical rating organization” as such term is defined for purposes of Rule 436(g)(2) under the Securities Act.

(d) Opinion of Counsel for the Company. On the Closing Date, the Representatives shall have received the favorable opinion of ▇▇▇▇▇▇ ▇▇▇▇▇▇ LLP, counsel for the Company, dated as of such Closing Date, the form of which is attached as Exhibit A.

(e) Opinion of Intellectual Property Counsel for the Company. On the Closing Date, the Representatives shall have received the favorable opinion of ▇▇▇▇▇ Day, intellectual property counsel to the Company, dated as of such Closing Date, the form of which is attached as Exhibit B.

(f) Opinion of Director of Intellectual Property for the Company. On the Closing Date, the Representatives shall have received the favorable opinion of the Director of Intellectual Property of the Company, dated as of such Closing Date, the form of which is attached as Exhibit C.

(g) Opinion of Counsel for the Underwriters. On the Closing Date, the Representatives shall have received the favorable opinion of ▇▇▇▇▇▇ Godward LLP, counsel for the Underwriters, dated as of such Closing Date, in form and substance satisfactory to, and addressed to, the Representatives, with respect to the issuance and sale of the Shares, the Registration Statement, the Prospectus (together with any supplement thereto), the Disclosure Package and other related matters as the Representatives may reasonably require, and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.

(h) Officers’ Certificate. On the Closing Date, the Representatives shall have received a written certificate executed by the Chairman of the Board, Chief Executive Officer or President of the Company and the Chief Financial Officer or Chief Accounting Officer of the Company, dated as of such Closing Date, to the effect that the signers of such certificate have carefully examined the Registration Statement, the Prospectus and any amendment or supplement thereto, any Issuer Free Writing Prospectus and any amendment or supplement thereto and this Agreement, to the effect set forth in subsections (b) and (c)(iii) of this Section 5, and further to the effect that:

(i) for the period from and after the date of this Agreement and prior to such Closing Date, there has not occurred any Material Adverse Change;

(ii) the representations, warranties and covenants of the Company set forth in Section 1 of this Agreement are true and correct on and as of the Closing Date with the same force and effect as though expressly made on and as of such Closing Date; and

(iii) the Company has complied with all the agreements hereunder and satisfied all the conditions on its part to be performed or satisfied hereunder at or prior to such Closing Date.

(i) Bring-down Comfort Letter. On the Closing Date, the Representatives shall have received from PricewaterhouseCoopers LLP, independent registered public accounting firm for the Company, a letter dated such date, in form and substance satisfactory to the Representatives, to the effect that they reaffirm the statements made in the letter furnished by them pursuant to subsection (a) of this Section 5, except that the specified date referred to therein for the carrying out of procedures shall be no more than three business days prior to the Closing Date.

(j) Lock-Up Agreement from Certain Securityholders of the Company. On or prior to the date hereof, the Company shall have furnished to the Representatives an agreement in the form of Exhibit D hereto from those parties listed on Exhibit E, and such agreement shall be in full force and effect on the Closing Date.

(k) Listing of Shares. The Shares shall have been listed and admitted and authorized for quotation on the Nasdaq Stock Market, Inc., and satisfactory evidence of such actions shall have been provided to the Representatives.

(l) Additional Documents. On or before the Closing Date, the Representatives and counsel for the Underwriters shall have received such information, documents and opinions as they may reasonably require for the purposes of enabling them to pass upon the issuance and sale

of the Shares as contemplated herein, or in order to evidence the accuracy of any of the representations and warranties, or the satisfaction of any of the conditions or agreements, herein contained.

If any condition specified in this Section 5 is not satisfied when and as required to be satisfied, this Agreement may be terminated by the Representatives by notice to the Company at any time on or prior to the Closing Date, which termination shall be without liability on the part of any party to any other party, except that Section 4, Section 6, Section 8 and Section 9 shall at all times be effective and shall survive such termination.

SECTION 6. Reimbursement of Underwriters’ Expenses. If this Agreement is terminated by the Representatives pursuant to Section 5, Section 7, Section 10 or Section 11, or if the sale to the Underwriters of the Shares on the Closing Date is not consummated because of any refusal, inability or failure on the part of the Company to perform any agreement herein or to comply with any provision hereof, the Company agrees to reimburse the Representatives and the other Underwriters (or such Underwriters as have terminated this Agreement with respect to themselves), severally, upon demand for all out-of-pocket expenses that shall have been reasonably incurred by the Representatives and the Underwriters in connection with the proposed purchase and the offering and sale of the Shares, including but not limited to fees and disbursements of counsel, printing expenses, travel expenses, postage, facsimile and telephone charges. The Company shall not be required to pay any costs, fees or compensation that would be deemed to be a “Prohibited Arrangement” as described in NASD Rule 2710(f)(2)(D).

SECTION 7. Effectiveness of this Agreement. This Agreement shall not become effective until the later of (i) the execution of this Agreement by the parties hereto and (ii) notification by the Commission to the Company and the Representatives of the effectiveness of the Registration Statement under the Securities Act.

Prior to such effectiveness, this Agreement may be terminated by any party by notice to each of the other parties hereto, and any such termination shall be without liability on the part of (a) the Company to any Underwriter, except that the Company shall be obligated to reimburse the expenses of the Representatives and the Underwriters pursuant to Sections 4 and 6 hereof or (b) of any Underwriter to the Company.

SECTION 8. Indemnification.

(a) Indemnification of the Underwriters. The Company agrees to indemnify and hold harmless each Underwriter, its directors, officers, employees and agents, and each person, if any, who controls any Underwriter within the meaning of the Securities Act and the Exchange Act against any loss, claim, damage, liability or expense, as incurred, to which such Underwriter or such controlling person may become subject, insofar as such loss, claim, damage, liability or expense (or actions in respect thereof as contemplated below) arises out of or is based (i) upon any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, or any amendment thereto, including any information deemed to be a part thereof pursuant to Rule 430A, Rule 430B or Rule 430C under the Securities Act, or the omission or alleged omission therefrom of a material fact required to be stated therein or necessary to make the statements therein not misleading; or (ii) upon any untrue statement or alleged untrue

statement of a material fact contained in any Issuer Free Writing Prospectus, any preliminary prospectus or the Prospectus (or any amendment or supplement thereto), or the omission or alleged omission therefrom of a material fact, in each case, necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, and to reimburse each Underwriter, its officers, directors, employees, agents and each such controlling person for any and all expenses (including the fees and disbursements of counsel chosen by BAS) as such expenses are reasonably incurred by such Underwriter, or its officers, directors, employees, agents or such controlling person in connection with investigating, defending, settling, compromising or paying any such loss, claim, damage, liability, expense or action; provided, however, that the foregoing indemnity agreement shall not apply to any loss, claim, damage, liability or expense to the extent, but only to the extent, arising out of or based upon any untrue statement or alleged untrue statement or omission or alleged omission made in reliance upon and in conformity with written information furnished to the Company by the Representatives expressly for use in the Registration Statement, any Issuer Free Writing Prospectus, any preliminary prospectus or the Prospectus (or any amendment or supplement thereto). The indemnity agreement set forth in this Section 8(a) shall be in addition to any liabilities that the Company may otherwise have.

(b) Indemnification of the Company, its Directors and Officers. Each Underwriter agrees, severally and not jointly, to indemnify and hold harmless the Company, each of its directors, each of its officers who signed the Registration Statement and each person, if any, who controls the Company within the meaning of the Securities Act or the Exchange Act, against any loss, claim, damage, liability or expense, as incurred, to which the Company, or any such director, officer or controlling person may become subject, insofar as such loss, claim, damage, liability or expense (or actions in respect thereof as contemplated below) arises out of or is based upon any untrue or alleged untrue statement of a material fact contained in the Registration Statement, any Issuer Free Writing Prospectus, any preliminary prospectus or the Prospectus (or any amendment or supplement thereto), or arises out of or is 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, and only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in the Registration Statement, any Issuer Free Writing Prospectus, any preliminary prospectus or the Prospectus (or any amendment or supplement thereto), in reliance upon and in conformity with written information furnished to the Company by the Representatives expressly for use therein; and to reimburse the Company, or any such director, officer or controlling person for any legal and other expense reasonably incurred by the Company, or any such director, officer or controlling person in connection with investigating, defending, settling, compromising or paying any such loss, claim, damage, liability, expense or action. The Company hereby acknowledges that the only information that the Underwriters have furnished to the Company expressly for use in the Registration Statement, any Issuer Free Writing Prospectus, any preliminary prospectus or the Prospectus (or any amendment or supplement thereto) are the statements set forth in the section entitled “Stabilization and Short Positions” concerning stabilization transactions by the Underwriters and in the section entitled “Commissions and Expenses” under the caption “Underwriting” in the Prospectus. The indemnity agreement set forth in this Section 8(b) shall be in addition to any liabilities that each Underwriter may otherwise have.

(c) Notifications and Other Indemnification Procedures. Promptly after receipt by an indemnified party under this Section 8 of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against an indemnifying party under this Section 8, notify the indemnifying party in writing of the commencement thereof, but the failure to so notify the indemnifying party (i) will not relieve it from liability under paragraph (a) or (b) above unless and to the extent it did not otherwise learn of such action and such failure results in the forfeiture by the indemnifying party of substantial rights and defenses and (ii) will not, in any event, relieve the indemnifying party from any obligations to any indemnified party other than the indemnification obligation provided in paragraph (a) or (b) above. In case any such action is brought against any indemnified party and such indemnified party seeks or intends to seek indemnity from an indemnifying party, the indemnifying party will be entitled to participate in, and, to the extent that it shall elect, jointly with all other indemnifying parties similarly notified, by written notice delivered to the indemnified party promptly after receiving the aforesaid notice from such indemnified party, to assume the defense thereof with counsel satisfactory to such indemnified party; provided, however, if the defendants in any such action include both the indemnified party and the indemnifying party and the indemnified party shall have reasonably concluded that a conflict may arise between the positions of the indemnifying party and the indemnified party in conducting the defense of any such action or that there may be legal defenses available to it and/or other indemnified parties that are different from or additional to those available to the indemnifying party, the indemnified party or parties shall have the right to select separate counsel to assume such legal defenses and to otherwise participate in the defense of such action on behalf of such indemnified party or parties. Upon receipt of notice from the indemnifying party to such indemnified party of such indemnifying party’s election so to assume the defense of such action and approval by the indemnified party of counsel, the indemnifying party will not be liable to such indemnified party under this Section 8 for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof unless (i) the indemnified party shall have employed separate counsel in accordance with the proviso to the preceding sentence (it being understood, however, that the indemnifying party shall not be liable for the expenses of more than one separate counsel (other than local counsel), reasonably approved by the indemnifying party (or by BAS and CIBC in the case of Section 8(b)), representing the indemnified parties who are parties to such action) or (ii) the indemnifying party shall not have employed counsel satisfactory to the indemnified party to represent the indemnified party within a reasonable time after notice of commencement of the action, in each of which cases the fees and expenses of counsel shall be at the expense of the indemnifying party.

(d) Settlements. The indemnifying party under this Section 8 shall not be liable for any settlement of any proceeding effected without its written consent, which shall not be withheld unreasonably, but if settled with such consent or if there is a final judgment for the plaintiff, the indemnifying party agrees to indemnify the indemnified party against any loss, claim, damage, liability or expense by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by Section 8(c) hereof, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if (i) such settlement is entered into more than 30 days after receipt by such indemnifying party of the aforesaid request and (ii) such indemnifying party shall not have reimbursed the indemnified party in accordance with such request prior to

the date of such settlement. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement, compromise or consent to the entry of judgment in any pending or threatened action, suit or proceeding in respect of which any indemnified party is or could have been a party and indemnity was or could have been sought hereunder by such indemnified party, unless such settlement, compromise or consent (x) includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such action, suit or proceeding and (y) 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.

SECTION 9. Contribution. If the indemnification provided for in Section 8 is for any reason unavailable to or otherwise insufficient to hold harmless an indemnified party in respect of any losses, claims, damages, liabilities or expenses referred to therein, then each indemnifying party shall contribute to the aggregate amount paid or payable by such indemnified party, as incurred, as a result of any losses, claims, damages, liabilities or expenses referred to therein (i) 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 hand, from the offering of the Shares pursuant to this Agreement or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company, on the one hand, and the Underwriters, on the other hand, in connection with the statements or omissions or inaccuracies in the representations and warranties herein which resulted in such losses, claims, damages, liabilities or expenses, 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 hand, in connection with the offering of the Shares pursuant to this Agreement shall be deemed to be in the same respective proportions as the total net proceeds from the offering of the Shares pursuant to this Agreement (before deducting expenses) received by the Company, and the total underwriting discount received by the Underwriters, in each case as set forth on the front cover page of the Prospectus bear to the aggregate public offering price of the Shares as set forth on such cover. The relative fault of the Company, on the one hand, and the Underwriters, on the other hand, shall be determined by reference to, among other things, whether any such untrue or alleged untrue statement of a material fact or omission or alleged omission to state a material fact or any such inaccurate or alleged inaccurate representation or warranty relates to information supplied by the Company, on the one hand, or the Underwriters, on the other hand, and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

The amount paid or payable by a party as a result of the losses, claims, damages, liabilities and expenses referred to above shall be deemed to include, subject to the limitations set forth in Section 8(c), any legal or other fees or expenses reasonably incurred by such party in connection with investigating or defending any action or claim.

The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this Section 9 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 that does not take account of the equitable considerations referred to in this Section 9.

Notwithstanding the provisions of this Section 9, no Underwriter shall be required to contribute any amount in excess of the underwriting commissions received by such Underwriter in connection with the Shares underwritten by it and distributed to the public. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Underwriters’ obligations to contribute pursuant to this Section 9 are several, and not joint, in proportion to their respective underwriting commitments as set forth opposite their names in Schedule A. For purposes of this Section 9, each director, officer, employee and agent of an Underwriter and each person, if any, who controls an Underwriter within the meaning of the Securities Act and the Exchange Act shall have the same rights to contribution as such Underwriter, and each director of the Company, each officer of the Company who signed the Registration Statement and each person, if any, who controls the Company within the meaning of the Securities Act and the Exchange Act shall have the same rights to contribution as the Company.

SECTION 10. Default of One or More of the Several Underwriters. If, on the Closing Date, any one or more of the several Underwriters shall fail or refuse to purchase Shares that it or they have agreed to purchase hereunder on such date, and the aggregate number of Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase does not exceed 10% of the aggregate number of the Shares to be purchased on such date, the other Underwriters shall be obligated, severally, in the proportions that the number of Shares set forth opposite their respective names on Schedule A bears to the aggregate number of Shares set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as may be specified by the Representatives with the consent of the non-defaulting Underwriters, to purchase the Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date. If, on the Closing Date, any one or more of the Underwriters shall fail or refuse to purchase Shares and the aggregate number of Shares with respect to which such default occurs exceeds 10% of the aggregate number of Shares to be purchased on such date, and arrangements satisfactory to the Representatives and the Company for the purchase of such Shares are not made within 48 hours after such default, this Agreement shall terminate without liability of any party to any other party except that the provisions of Section 4, Section 6, Section 8 and Section 9 shall at all times be effective and shall survive such termination. In any such case either the Representatives or the Company shall have the right to postpone the Closing Date, but in no event for longer than seven days in order that the required changes, if any, to the Registration Statement and the Prospectus or any other documents or arrangements may be effected.

As used in this Agreement, the term “Underwriter” shall be deemed to include any person substituted for a defaulting Underwriter under this Section 10. Any action taken under this Section 10 shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

SECTION 11. Termination of this Agreement. Prior to the Closing Date this Agreement may be terminated by the Representatives by notice given to the Company if at any time (i) trading or quotation in any of the Company’s securities shall have been suspended or limited by the Commission or by the Nasdaq Stock Market, Inc., or trading in securities generally on the New York Stock Exchange or the Nasdaq Stock Market, Inc. shall have been suspended or

limited, or minimum or maximum prices shall have been generally established on any of such stock exchanges by the Commission or the NASD; (ii) a general banking moratorium shall have been declared by federal or New York authorities or a material disruption in commercial banking or securities settlement or clearance services in the United States has occurred; (iii) there shall have occurred any outbreak or escalation of national or international hostilities or any crisis or calamity, or any change in the United States or international financial markets, or any substantial change or development involving a prospective substantial change in United States’ or international political, financial or economic conditions, as in the judgment of the Representatives is material and adverse and makes it impracticable or inadvisable to market the Shares in the manner and on the terms described in the Prospectus or to enforce contracts for the sale of securities or (iv) in the judgment of the Representatives, there has been, since the time of execution of this Agreement or since the respective dates as of which information is given in the Prospectus, any material adverse change in the assets, properties, condition, financial or otherwise, or in the results of operations, business affairs or business prospects of the Company considered as a whole, whether or not arising in the ordinary course of business. Any termination pursuant to this Section 11 shall be without liability on the part of (a) the Company to any Underwriter, or (b) any Underwriter to the Company, except that (y) if this Agreement is terminated by the Representatives because of any failure, refusal or inability on the part of the Company to comply with the terms or to fulfill any of the conditions of this Agreement, the Company will reimburse the Underwriters for all out-of-pocket expenses (including the reasonable fees and disbursements of their counsel) incurred by them in connection with the proposed purchase and sale of the Shares or in contemplation of performing their obligations hereunder and (z) no Underwriter who shall have failed or refused to purchase the Shares agreed to be purchased by it under this Agreement, without some reason sufficient hereunder to justify cancellation or termination of its obligations under this Agreement, shall be relieved of liability to the Company or to the other Underwriters for damages occasioned by its failure or refusal.

SECTION 12. No Advisory or Fiduciary Responsibility. The Company acknowledges and agrees that: (i) the purchase and sale of the Securities pursuant to this Agreement, including the determination of the offering price of the Securities and any related discounts and commissions, is an arm’s-length commercial transaction between the Company, on the one hand, and the several Underwriters, on the other hand, and the Company is capable of evaluating and understanding and understands and accepts the terms, risks and conditions of the transactions contemplated by this Agreement; (ii) in connection with each transaction contemplated hereby and the process leading to such transaction each Underwriter is and has been acting solely as a principal and is not the financial advisor, agent or fiduciary of the Company or its affiliates, stockholders, creditors or employees or any other party; (iii) no Underwriter has assumed or will assume an advisory, agency or fiduciary responsibility in favor of the Company with respect to any of the transactions contemplated hereby or the process leading thereto (irrespective of whether such Underwriter has advised or is currently advising the Company on other matters) and no Underwriter has any obligation to the Company with respect to the offering contemplated hereby except the obligations expressly set forth in this Agreement; (iv) the several Underwriters and their respective affiliates may be engaged in a broad range of transactions that involve interests that differ from those of the Company and that the several Underwriters have no obligation to disclose any of such interests by virtue of any advisory, agency or fiduciary relationship; and (v) the Underwriters have not provided any legal, accounting, regulatory or tax

advice with respect to the offering contemplated hereby and the Company has consulted its own legal, accounting, regulatory and tax advisors to the extent it deemed appropriate.

This Agreement supersedes all prior agreements and understandings (whether written or oral) between the Company and the several Underwriters, or any of them, with respect to the subject matter hereof. The Company hereby waives and releases, to the fullest extent permitted by law, any claims that the Company may have against the several Underwriters with respect to any breach or alleged breach of agency or fiduciary duty.

SECTION 13. Representations and Indemnities to Survive Delivery. The respective indemnities, agreements, representations, warranties and other statements of the Company, of its officers and of the several Underwriters set forth in or made pursuant to this Agreement (i) will remain operative and in full force and effect, regardless of any (A) investigation, or statement as to the results thereof, made by or on behalf of any Underwriter, the officers or employees of any Underwriter, or any person controlling the Underwriter, the Company, the officers or employees of the Company, or any person controlling the Company, as the case may be or (B) acceptance of the Shares and payment for them hereunder and (ii) will survive delivery of and payment for the Shares sold hereunder and any termination of this Agreement.

SECTION 14. Notices. All communications hereunder shall be in writing and shall be mailed, hand delivered or telecopied and confirmed to the parties hereto as follows:

If to the Representatives:

Banc of America Securities LLC

▇ ▇▇▇▇ ▇▇^▇▇ ▇▇▇▇▇▇

▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇

Facsimile: (▇▇▇) ▇▇▇-▇▇▇▇

Attention: Syndicate Department

with a copy to:

Banc of America Securities LLC

▇ ▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇ ▇▇▇ ▇▇▇▇,

▇▇▇ ▇▇▇▇ ▇▇▇▇▇

Facsimile: (▇▇▇) ▇▇▇-▇▇▇▇

Attention: Legal Department

If to the Company:

Seattle Genetics, Inc.

▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇

▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇

Facsimile: (▇▇▇) ▇▇▇-▇▇▇▇

Attention: Chief Executive Officer

with copy to:

Seattle Genetics, Inc.

▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇

▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇

Facsimile: (▇▇▇) ▇▇▇-▇▇▇▇

Attention: General Counsel

Any party hereto may change the address for receipt of communications by giving written notice to the others.

SECTION 15. Successors and Assigns. This Agreement will inure to the benefit of and be binding upon the parties hereto, including any substitute Underwriters pursuant to Section 10 hereof, and to the benefit of (i) the Company, its directors, any person who controls the Company within the meaning of the Securities Act and the Exchange Act and any officer of the Company who signs the Registration Statement, (iii) the Underwriters, the officers, directors, employees and agents of the Underwriters, and each person, if any, who controls any Underwriter within the meaning of the Securities Act and the Exchange Act, and (v) the respective successors and assigns of any of the above, all as and to the extent provided in this Agreement, and no other person shall acquire or have any right under or by virtue of this Agreement. The term “successors and assigns” shall not include a purchaser of any of the Shares from any of the several Underwriters merely because of such purchase.

SECTION 16. Partial Unenforceability. The invalidity or unenforceability of any Section, paragraph or provision of this Agreement shall not affect the validity or enforceability of any other Section, paragraph or provision hereof. If any Section, paragraph or provision of this Agreement is for any reason determined to be invalid or unenforceable, there shall be deemed to be made such minor changes (and only such minor changes) as are necessary to make it valid and enforceable.

SECTION 17. Governing Law Provisions. THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

SECTION 18. General Provisions. This Agreement constitutes the entire agreement of the parties to this Agreement and supersedes all prior written or oral and all contemporaneous oral agreements, understandings and negotiations with respect to the subject matter hereof. This Agreement may be executed in two or more counterparts, each one of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument. This Agreement may not be amended or modified unless in writing by all of the parties hereto, and no condition herein (express or implied) may be waived unless waived in writing by each party whom the condition is meant to benefit. The Section headings herein are for the convenience of the parties only and shall not affect the construction or interpretation of this Agreement.

Each of the parties hereto acknowledges that it is a sophisticated business person who was adequately represented by counsel during negotiations regarding the provisions hereof, including, without limitation, the indemnification provisions of Section 8 and the contribution provisions of Section 9, and is fully informed regarding said provisions. Each of the parties hereto further acknowledges that the provisions of Sections 8 and 9 hereto fairly allocate the risks in light of the ability of the parties to investigate the Company, its affairs and its business in order to assure that adequate disclosure has been made in the Registration Statement, any preliminary prospectus and the Prospectus (and any amendments and supplements thereto), as required by the Securities Act and the Exchange Act.

If the foregoing is in accordance with your understanding of our agreement, kindly sign and return to the Company the enclosed copies hereof, whereupon this instrument, along with all counterparts hereof, shall become a binding agreement in accordance with its terms.


Very truly yours,

SEATTLE GENETICS, INC.

By:		/s/ ▇▇▇▇ ▇. ▇▇▇▇▇▇▇
Name:		▇▇▇▇ ▇. ▇▇▇▇▇▇▇, Ph.D.
Title:		President and Chief Executive Officer

The foregoing Underwriting Agreement is hereby confirmed and accepted by the Representatives as of the date first above written.

BANC OF AMERICA SECURITIES LLC

CIBC WORLD MARKETS CORP.

Acting as Representatives of the several Underwriters named in the attached Schedule A.


BANC OF AMERICA SECURITIES LLC

By		Banc of America Securities LLC

/s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇
Name:		▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇
Title:		Managing Director, Head of Equity Syndicate

CIBC WORLD MARKETS CORP.

By:		/s/ ▇▇▇▇ ▇▇▇▇▇▇▇
Name:		▇▇▇▇ ▇▇▇▇▇▇▇
Title:		Executive Director, Equity Capital Markets

SCHEDULE A


Underwriters		Number of Shares to be Purchased
Banc of America Securities LLC		3,650,000
CIBC World Markets Corp.		3,650,000
Total		7,300,000

SCHEDULE B

Schedule of Free Writing Prospectuses included in the Disclosure Package

None

SCHEDULE C

Pricing Information

Price to Investors: As to each investor in the Shares, the price per share paid by such investor.

EXHIBIT A

Form of Opinion of Counsel for the Company

Opinion of counsel for the Company to be delivered pursuant to Section 5(d) of the Underwriting Agreement.

References to the Prospectus in this Exhibit A include any supplements thereto at the Closing Date.

(i) The Company has been duly incorporated and is in good standing as a corporation under the laws of the State of Delaware, with full corporate power and authority to own or lease, as the case may be, and to operate its properties and conduct its business as described in the Prospectus; the Company is duly authorized to transact business in the corporate form as a foreign corporation under the laws of the State of Washington;

(ii) The Company’s authorized equity capitalization is as set forth in the Prospectus; the capital stock of the Company conforms in all material respects to the description thereof contained in the Prospectus; the Shares have been duly and validly authorized, and, when issued and delivered to and paid for by the Underwriters pursuant to the Underwriting Agreement, will be fully paid and nonassessable; the Shares are duly listed, and admitted and authorized for trading, subject to official notice of issuance, on the Nasdaq National Market; the Form Certificate is in valid and sufficient form; the holders of outstanding shares of capital stock of the Company are not entitled to preemptive or other rights to subscribe for the Shares under the Delaware General Corporation Law or the Certificate of Incorporation or Bylaws, or, to such counsel’s knowledge, any other agreement to which the Company is a party; and, except as set forth in the Prospectus, to such counsel’s knowledge, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, shares of capital stock of or ownership interests in the Company are outstanding;

(iii) To such counsel’s knowledge, there is no pending or threatened action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or its property of a character required to be disclosed in the Registration Statement that is not disclosed in the Prospectus, and, to such counsel’s knowledge, there is no franchise, contract or other document of a character required to be described in the Registration Statement or Prospectus, or to be filed as an exhibit thereto, which is not described or filed as required; and the statements included or incorporated by reference in the Prospectus under the headings “Description of Capital Stock” and in the Registration Statement in Part II – Item 15 insofar as such statements summarize legal matters, agreements, documents or proceedings discussed therein, fairly represent the information called for with respect to such legal matters, agreements, documents or proceedings and fairly summarize the matters referred to therein;

(iv) The Registration Statement has become effective under the Securities Act; any required filing of the Prospectus, any Preliminary Prospectus and the Prospectus, and any supplements thereto, pursuant to Rule 424(b) has been made in the manner and within the time

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period required by Rule 424(b); to such counsel’s knowledge, no stop order suspending the effectiveness of the Registration Statement has been issued, no proceedings for that purpose have been instituted or threatened; the Registration Statement and the Prospectus (other than the financial statements and other financial and statistical information contained therein, as to which such counsel need not express an opinion) comply as to form in all material respects with the applicable requirements of the Securities Act and the rules thereunder; each document filed pursuant to the Exchange Act and incorporated by reference in the Registration Statement and the Prospectus (other than the financial statements and other financial and statistical information contained therein, as to which such counsel need not express an opinion) complied as to form when so filed in all material respects with the applicable requirements of the Exchange Act and the rules thereunder;

(v) The Underwriting Agreement has been duly authorized, executed and delivered by the Company;

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

(vii) No consent, approval, authorization, filing with or order of any court or governmental agency or body is required in connection with the transactions contemplated herein, except such as have been filed or obtained under the Securities Act, filed under the Exchange Act and such as may be required under the blue sky laws of any jurisdiction in connection with the purchase and distribution of the Shares by the Underwriters in the manner contemplated in the Underwriting Agreement and in the Prospectus as to which we express no opinion;

(viii) Neither the issue and sale of the Shares nor the fulfillment of the terms of the Underwriting Agreement will (i) conflict with the Company’s Certificate of Incorporation or Bylaws, (ii) result in a breach or violation of, or imposition of any lien, charge or encumbrance upon any property or assets of the Company pursuant to the terms of any agreement or instrument to which the Company is a party or bound or to which its property is subject and which has been filed by the Company pursuant to the requirements of the Exchange Act, or (iii) violate any statute, any rule or regulation of any governmental agency or body, or to such counsel’s knowledge, any judgment, order or decree applicable to the Company of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Company or any of its properties;

(ix) To such counsel’s knowledge, no holders of securities of the Company have rights to the registration of such securities under the Registration Statement, other than rights that have been waived in connection with the transactions contemplated by the Registration Statement;

(x) The statements in the Annual Report on Form 10-K for the year ended December 31, 2005 in the section entitled “BUSINESS – Government Regulation,” “RISK FACTORS—Risks Related to our Business—Clinical trials for our product candidates are expensive, time consuming and their outcome is uncertain,” “—Our clinical trials may take longer to complete

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than we project or they may not be completed at all,” “—We currently rely on third-party manufacturers and other third parties for production of our drug products and our dependence on these manufacturers may impair the development of our product candidates,” and “Our second generation ADC technology is still at an early stage of development and has not yet entered human clinical trials,” insofar as such statements purport to describe or summarize particular United States Food and Drug Administration (the “FDA”) requirements including procedures under the Federal Food, Drug and Cosmetic Act and Public Health Service Act or the FDA regulations, are accurate and complete in all material respects and fairly present the information purported to be described or summarized and insofar as such statements relate to FDA regulatory matters; and

(xi) To such counsel’s knowledge, there are no FDA enforcement actions or proceedings pending or threatened against the Company.

In addition, such counsel shall include a statement to the effect that although such counsel has not undertaken to determine independently the accuracy, completeness or fairness of any of the statements made in the Registration Statement, the Disclosure Package or the Prospectus, such counsel has reviewed the Registration Statement, the Disclosure Package and the Prospectus and participated in conferences with representatives of the Company, its accountants, the Underwriters and Underwriters’ counsel at which the contents of the Registration Statement, the Disclosure Package and the Prospectus and related matters were discussed and reviewed. On the basis of the information which was developed in the course of the performance of the services referred to above, considered in the light of such counsel’s understanding of the applicable law, including the requirements of Form S-3, such counsel has no reason to believe that, on the date it became effective contained any untrue statement of a material fact or omitted to state any material fact required to be stated therein or necessary to make the statements therein not misleading or that the Disclosure Package as of the Applicable Time and the Prospectus as of its date and on the Closing Date included or includes any untrue statement of a material fact or omitted or omits to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading (in each case, other than the financial statements and other financial and statistical information derived therefrom, as to which we express no opinion). The limitations inherent in the independent verification of factual matters and the character of determinations involved in the registration process are such, however, that we do not assume any responsibility for the accuracy, completeness or fairness of the statements contained in the Registration Statement, Disclosure Package, and the Prospectus except to the extent set forth in Paragraphs (iii) and (x) above.

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EXHIBIT B

Form of Opinion of Intellectual Property Counsel for the Company

Opinion of counsel for the Company to be delivered pursuant to Section 5(e) of the Underwriting Agreement. References to the Prospectus in this Exhibit B include any supplements thereto at the Closing Date.

Based upon, and subject to the foregoing, and a review of such matters of law as we have deemed appropriate, it is our opinion and judgment that:

1. Based upon our review of the IP Portions and review of the U.S. Patent Applications, the statements under the IP Portions, to the best of our knowledge and solely insofar as such statements concern descriptions of legal matters related to the U.S. Patent Applications or documents related to the U.S. Patent Applications, but excluding matters relating to (a) licenses and other agreements and (b) numbers of patents and patent applications, fairly summarize in all material respects such matters or documents.

2. While there can be no guarantee that any particular patent application will issue as a patent, to the best of our knowledge, each of the U.S. Patent Applications has been properly filed and is being prosecuted in the United States Patent and Trademark Office, although small entity status for the purpose of paying reduced fees was erroneously established in certain instance(s). Based on the representations of the Company that small entity status was established in good faith and that fees as a small entity were paid in good faith, we intend to correct these error(s) as necessary.

3. Except as described in the IP Portions, to the best of our knowledge, there are no material legal or governmental proceedings, other than proceedings before the United States Patent and Trademark Office, pending or threatened, with respect to any of the U.S. Patent Applications.

4. To the best of our knowledge, the Company is the assignee of each of the U.S. patent applications listed in Schedule A, except for U.S. Patent Application No. 10/558,811.

5. Except as set forth in the IP Portions, to the best of our knowledge, the Company has not received any notice with respect to the potential infringement of any patents of others.

6. Except as described in the IP Portions and without any searches or an evaluation having been conducted for the purpose of rendering this opinion, to the best of our knowledge, the Company is not infringing any patents of others.

7. While there can be no guarantee that our docketing process is error-free, to the best of our knowledge we have docketed the maintenance fee and annuity deadlines for the U.S. patents, foreign patents, and foreign applications listed in Schedule B.

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EXHIBIT C

Form of Opinion of Director of Intellectual Property of the Company

Opinion of counsel for the Company to be delivered pursuant to Section 5(f) of the Underwriting Agreement. References to the Prospectus in this Exhibit C include any supplements thereto at the Closing Date.

Based upon, and subject to the foregoing, and a review of such matters of law as we have deemed appropriate, it is our opinion and judgment that:

1. The Company prepared or had prepared on its behalf by outside legal counsel the pending United States, international and foreign patent applications listed in Schedule A (“the SGEN Patent Applications”).

2. The Company prosecutes and/or supervises outside legal counsel in the prosecution of the SGEN Patent Applications.

3. While there can be no guarantee that any particular patent application will issue as a patent, to the best of our knowledge, each of the SGEN Patent Applications has been properly filed, although small entity status for the purpose of paying reduced fees was erroneously established in certain instances and is currently being corrected as necessary, and is being prosecuted in the United States Patent and Trademark Office or respective foreign patent office. Furthermore, to the best of our knowledge, the duty to disclose has been or is being complied with for each patent application and patent listed on Schedule A and B, respectively.

4. Except as described in the IP Portions, to the best of our knowledge, there are no material legal or governmental proceedings, other than proceedings before the United States Patent and Trademark Office or respective foreign patent office, pending or threatened, with respect to any of the SGEN Patent Applications.

5. To the best of our knowledge, the Company is the assignee of or is the recipient of an obligation to assign each of the SGEN patent applications and patents listed in Schedule A and B, respectively.

6. Except as set forth in the IP Portions, to the best of our knowledge, the Company is not a party to any injunctions or lawsuits with respect to the potential infringement of any patents of others.

7. Except as described in the IP Portions and without any searches or an evaluation having been conducted for the purpose of rendering this opinion, to the best of our knowledge, the Company is not infringing any U.S. patents of others.

8. The maintenance fee and annuity deadlines for the U.S. patents, foreign patents, and foreign applications listed in Schedules A and B, as applicable, are docketed by outside legal counsel. We instruct outside legal counsel to pay such maintenance fees and annuities as necessary and appropriate.

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EXHIBIT D

Form of Lock Up Agreement

March __, ▇▇▇▇

▇▇▇▇ ▇▇ ▇▇▇▇▇▇▇ Securities LLC

CIBC World Markets Corp.

c/o Banc of America Securities LLC

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Re:	Public Offering of Common Stock of Seattle Genetics, Inc. (the “Company”)

Ladies and Gentlemen:

The undersigned is an owner of record or beneficially of certain shares of Common Stock of the Company (“Common Stock”) or securities convertible into or exchangeable or exercisable for Common Stock. The Company proposes to carry out a public offering of Common Stock pursuant to a Registration Statement on Form S-3, File No. 333-120703 (the “Registration Statement”) which was declared effective by the Securities and Exchange Commission (the “Commission”) on or about August 4, 2005 for the registration of shares of Common Stock with an aggregate maximum offering price of $75.0 million (the “Offering”) for which you will act as the underwriters. The undersigned recognizes that the Offering will be of benefit to the undersigned and will benefit the Company. The undersigned acknowledges that you are relying on the representations and agreements of the undersigned contained in this letter in carrying out the Offering and in entering into underwriting arrangements with the Company with respect to the Offering.

In consideration of the foregoing, the undersigned hereby agrees that the undersigned will not, (and will cause any spouse or immediate family member of the spouse or the undersigned living in the undersigned’s household not to), without the prior written consent of Banc of America Securities LLC (“BAS”) and CIBC World Markets Corp. (“CIBC”) (which consent may be withheld in their sole discretion), directly or indirectly, sell, offer, contract or grant any option to sell (including without limitation any short sale), pledge, transfer, establish an open “put equivalent position” or liquidate or decrease a “call equivalent position” within the meaning of Rule 16a-1(h) under the Securities Exchange Act of 1934, as amended, or otherwise dispose of or transfer (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition of) including the filing (or participation in the filing of) of a registration statement with the Securities and Exchange Commission in respect of, any shares of Common Stock, options or warrants to acquire shares of Common Stock, or securities exchangeable or exercisable for or convertible into shares of Common Stock currently or hereafter owned either of record or beneficially (as

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defined in Rule 13d-3 under the Securities Exchange Act of 1934, as amended) by the undersigned (or such spouse or family member), or publicly announce an intention to do any of the foregoing, for a period commencing on the date hereof and continuing through the close of trading on the date 90 days after the date of the Prospectus (the “Lock-Up Period”), provided however, that the foregoing sentence shall not apply to the transfer of any or all of the shares of Common Stock owned by the undersigned, to the extent the undersigned is an individual, either during his or her lifetime or on death, by gift, will or intestate succession to the immediate family of the undersigned or to a trust the beneficiaries of which are exclusively the undersigned and/or a member or members of his or her immediate family; provided, however, that in any such case it shall be a condition to such transfer that the transferee executes and delivers to BAS and CIBC an agreement stating that the transferee is receiving and holding the Common Stock subject to the provisions of this letter agreement, and there shall be no further transfer of such Common Stock except in accordance with this letter. In addition, the undersigned agrees that, without the prior written consent of BAS and CIBC, 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 Common Stock or any security convertible into or exercisable or exchangeable for Common Stock. With respect to the Offering only, the undersigned waives any registration rights relating to registration under the Securities Act of any Common Stock owned either of record or beneficially by the undersigned, including any rights to receive notice of the Offering.

This agreement is effective as of the date hereof and shall expire automatically if the Underwriting Agreement is not entered into on or before May 1, 2006.

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This agreement is irrevocable and will be binding on the undersigned and the respective successors, heirs, personal representatives, and assigns of the undersigned.

Printed Name of Holder



By:
		Signature

Printed Name of Person Signing

(and indicate capacity of person signing if signing as custodian, trustee, or on behalf of an entity)

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EXHIBIT E

Lock Up Signatories

JPMP Capital Corp.

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SEATTLE GENETICS, INC. Common Stock UNDERWRITING AGREEMENT dated March 29, 2006

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