Seattle Genetics’ Antibody-Drug Conjugate Technology Utilized in Genentech’s Polivy, Now Approved by FDA

-Approval Triggers Milestone Payment and Royalties on Worldwide Net Sales-

Seattle Genetics, Inc. (Nasdaq:SGEN) today announced U.S. Food and Drug Administration (FDA) approval of Polivy™ (polatuzumab vedotin-piiq), which is an antibody-drug conjugate (ADC) targeting CD79b that utilizes Seattle Genetics’ technology. Polivy was developed and will be commercialized by Genentech, a member of the Roche Group. It was approved in combination with bendamustine plus Rituxan® (rituximab) (BR) for the treatment of adults with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL), who have received at least two prior therapies. Polivy previously received FDA Breakthrough Therapy Designation, and was approved more than two months ahead of the Prescription Drug User Fee Act (PDUFA) action date of August 19, 2019.

“The approval of Polivy under our collaboration with Genentech is an important milestone for Seattle Genetics as it extends the reach of our technology to more patients with significant unmet medical needs,” said Clay Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. “This approval, along with our own internal ADCs in development and those of other collaborators, such as GlaxoSmithKline, highlights that ADCs continue to grow as an important therapeutic approach to treating both hematologic malignancies and solid tumors.”

Polivy was granted PRIME (PRIority MEdicines) designation by the European Medicines Agency (EMA) for the treatment of patients with R/R DLBCL. PRIME is a designation implemented by the EMA to support data generation and development plans for promising medicines, providing a pathway for accelerated evaluation by the agency. Polivy is also being investigated by Genentech in several ongoing clinical trials for the treatment of non-Hodgkin lymphoma (NHL), including frontline DLBCL.

Seattle Genetics’ ADC technology combines the specificity of monoclonal antibodies, innovative linker systems and potent cell-killing agents to treat cancer. The technology has been licensed to several companies, including Genentech and GlaxoSmithKline. Under the terms of these agreements, each company has rights to use the technology with antibodies against selected targets. The licensee is responsible for research, product development, manufacturing and commercialization. Seattle Genetics is entitled to receive fees, progress-dependent milestone payments and royalties on worldwide net sales of any resulting ADC products.

About Seattle Genetics

Seattle Genetics, Inc. is an emerging multi-product, global biotechnology company that develops and commercializes transformative therapies targeting cancer to make a meaningful difference in people’s lives. ADCETRIS® (brentuximab vedotin) utilizes the company’s industry-leading antibody-drug conjugate (ADC) technology and is currently approved for the treatment of multiple CD30-expressing lymphomas. Beyond ADCETRIS, the company has established a pipeline of novel targeted therapies at various stages of clinical testing, including three in ongoing pivotal trials for solid tumors. Enfortumab vedotin for metastatic urothelial cancer and tisotumab vedotin for metastatic cervical cancer utilize our proprietary ADC technology. Tucatinib, a small molecule tyrosine kinase inhibitor, is in a pivotal trial for HER2-positive metastatic breast cancer. In addition, we are leveraging our expertise in empowered antibodies to build a portfolio of proprietary immuno-oncology agents in clinical trials targeting hematologic malignancies and solid tumors. The company is headquartered in Bothell, Washington, and has a European office in Switzerland. For more information on our robust pipeline, visit www.seattlegenetics.com and follow @SeattleGenetics on Twitter.

Forward-Looking Statements

Certain of the statements made in this press release are forward looking, such as those, among others, relating to the company’s transition into a multi-product global oncology company, the therapeutic importance of ADCs, the commercial potential of Polivy including the potential for its approval for use in the European Economic Area for the treatment of R/R DLBCL and the potential for its approval in the United States and other territories in additional indications, the potential for Genentech and GlaxoSmithKline to pay the company milestones and royalties, as well as other statements that are not historical facts. 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 the risks and uncertainties associated with commercializing Polivy due to competition, unexpected adverse events, regulatory action, reimbursement, market adoption by physicians or other factors. Genentech may also be delayed or unsuccessful in its planned clinical trial initiations, the enrollment in and conduct of its clinical trials, obtaining data from clinical trials, planned regulatory submissions, and regulatory approvals in each case for a variety of reasons including the difficulty and uncertainty of pharmaceutical product development, negative or disappointing clinical trial results, unexpected adverse events or regulatory discussions or actions and the inherent uncertainty associated with the regulatory approval process. More information about the risks and uncertainties faced by Seattle Genetics is contained under the caption “Risk Factors” in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2019 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 except as required by applicable law.

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