TOKYO and BOTHELL, Wash., – March 26, 2018 – Astellas Pharma Inc. (TSE: 4503, President and CEO: Yoshihiko Hatanaka, “Astellas”) and Seattle Genetics, Inc. (NASDAQ: SGEN) today announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation to enfortumab vedotin, an antibody-drug conjugate (ADC), for patients with locally advanced or metastatic urothelial cancer who were previously treated with checkpoint inhibitors (CPI).

Breakthrough Therapy Designation is a process designed to expedite the development and review of drugs that are intended to treat a serious or life-threatening condition. It is based upon preliminary clinical evidence indicating that the drug may demonstrate substantial improvement over available therapy on a clinically significant endpoint(s).

“The FDA Breakthrough Therapy Designation underscores the potential of enfortumab vedotin as a meaningful treatment for patients with locally advanced or metastatic urothelial cancer. Further, it supports our rapid development plans for this ADC, including the ongoing pivotal study in this patient population,” said Robert Lechleider, M.D., Vice President, Clinical Development at Seattle Genetics. “Seattle Genetics is an emerging multi-product oncology company, advancing a robust pipeline with the goal of improving outcomes for cancer patients. Enfortumab vedotin is at the forefront of our late-stage clinical pipeline, and we are working closely with our partner and the FDA to bring this potential new treatment to patients as quickly as possible.”

“Achieving Breakthrough Therapy Designation for enfortumab vedotin is another step forward in our goal to bring an additional treatment option to patients who need it most,” said Steven Benner, M.D., Senior Vice President and Global Therapeutic Area Head, Oncology Development at Astellas. “With the enfortumab vedotin registrational phase 2 trial and CPI-combination trial actively underway, Astellas looks forward to expanding development of enfortumab vedotin and its oncology pipeline, including treatments that would target some of the hardest-to-treat cancers.”

The Breakthrough Therapy Designation was granted based on interim results from the phase 1 study examining enfortumab vedotin as monotherapy treatment for patients with metastatic urothelial cancer who were previously treated with CPIs. Enfortumab vedotin is being studied in a pivotal clinical trial, EV-201 (NCT03219333), as monotherapy in this patient setting and in an early-phase clinical trial in combination with CPI therapy, EV-103 (NCT03288545). The companies are also evaluating enfortumab vedotin in other solid tumors, including ovarian and non-small cell lung carcinoma.

More information about the ongoing trials can be found at www.clinicaltrials.gov.