Seattle Genetics Inc Wa (SGEN) SEC Filing 10-K Annual report for the fiscal year ending Thursday, December 31, 2015

Exhibit 99.1

Seattle Genetics Reports Fourth Quarter and

Year 2015 Financial Results

-Total 2015 Revenues of $336.8 Million, Including $226.1 Million in

ADCETRIS^® (Brentuximab Vedotin) U.S. and Canada Net Product Sales-

-Total 2016 Revenues Expected to Increase to a Range of $390 Million to $430 Million, Including ADCETRIS U.S. and Canada Net Sales of $255 Million to $275 Million-

-Vadastuximab Talirine (SGN-CD33A) Phase 3 Trial Initiation Planned

by Third Quarter of 2016-

-Data from ADCETRIS Phase 3 ALCANZA Trial Expected in Second Half of 2016-

-Conference Call Today at 4:30 p.m. ET-

Bothell, WA — February 9, 2016

“In 2015, we demonstrated significant progress across our corporate priorities. For ADCETRIS, we achieved record sales in the fourth quarter and for the year, received FDA approval for an expanded label, completed enrollment in two of three ongoing phase 3 trials and continued our efforts to establish ADCETRIS as the foundation of care for CD30-expressing lymphomas,” said Clay Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. “We also showed substantial progress with our pipeline. We plan to initiate a phase 3 trial with 33A in acute myeloid leukemia later this year, and we are advancing more than a dozen other clinical and preclinical programs in development for a range of hematologic malignancies and solid tumors. With a strong financial position, we are well-positioned to continue delivering on our aggressive commercial, clinical and research goals.”

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