Seattle Genetics Announces Proposed Public Offering of Common Stock

BOTHELL, Wash.–(BUSINESS WIRE)–Seattle Genetics, Inc. (Nasdaq: SGEN) today announced that it has commenced an underwritten public offering of 6,000,000 shares of its common stock. All of the shares are being offered by Seattle Genetics. In addition, Seattle Genetics expects to grant the underwriters of the offering a 30-day option to purchase up to an additional 900,000 shares of its common stock solely to cover overallotments at the public offering price, less the underwriting discounts and commissions. The offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering will be completed, or as to the actual size or terms of the offering.

Seattle Genetics anticipates using the net proceeds from the offering to fund ongoing commercialization of ADCETRIS in the United States and Canada, to fund its activities in preparation for the potential commercial launch of enfortumab vedotin, if approved by the FDA, to fund its research and development efforts designed to further expand the ADCETRIS label and to advance its pipeline of product candidates, as well as for general corporate purposes, including working capital. Seattle Genetics may also use a portion of the net proceeds to in-license, acquire or invest in complementary products, technologies, businesses or other assets or pursue other strategic opportunities although at this time Seattle Genetics has no material agreements or commitments with respect to any new in-license or acquisition opportunity.

J.P. Morgan Securities LLC, SVB Leerink LLC and Goldman Sachs & Co. LLC are acting as joint book-running managers for the offering.

A shelf registration statement relating to the shares was previously filed with and became effective by rule of the Securities and Exchange Commission. The offering is being made solely by means of a prospectus. A preliminary prospectus supplement and accompanying prospectus relating to the offering will be filed with the Securities and Exchange Commission and will be available on the Securities and Exchange Commission’s website located at http://www.sec.gov. A copy of the preliminary prospectus supplement and accompanying prospectus relating to the offering, when available, may be obtained from: J.P. Morgan Securities LLC, Attention: Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, by telephone at (866) 803-9204 or by email at [email protected]; SVB Leerink LLC, Attention: Syndicate Department, One Federal Street, 37th Floor, Boston, MA 02110, by telephone at (800) 808-7525, ext. 6132, or by email at [email protected]; or Goldman Sachs & Co. LLC, Prospectus Department, 200 West Street, New York, NY 10282, by telephone at (866) 471-2526, by facsimile at (212) 902-9316 or by email at [email protected].

This press release shall not constitute an offer to sell or the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Seattle Genetics

Seattle Genetics is a biotechnology company that develops and commercializes therapies targeting cancer.

Forward Looking Statements

Certain of the statements made in this press release are forward looking, such as those, among others, relating to Seattle Genetics’ expectations regarding the completion, timing and size of the public offering, its expectations with respect to granting the underwriters a 30-day option to purchase additional shares and its anticipated use of net proceeds from the offering. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include risks and uncertainties related to completion of the public offering on the anticipated terms or at all, market conditions and the satisfaction of customary closing conditions related to the public offering. More information about the risks and uncertainties faced by Seattle Genetics is contained in the section captioned “Risk Factors” in the preliminary prospectus supplement related to the public offering to be filed with the Securities and Exchange Commission. Seattle Genetics disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Contacts

Investors:

Peggy Pinkston

425-527-4160

[email protected]

or

Media:

Monique Greer

425-527-4641

[email protected]