Astellas and Seattle Genetics Initiate Phase 1b Trial of Enfortumab Vedotin in Combination with Immune Checkpoint Inhibitor Therapies in Locally Advanced or Metastatic Urothelial Cancer

ADC Combination Study Focuses on First-Line Treatment

TOKYO, Japan and BOTHELL, WA, USA I November 8, 2017 I Astellas Pharma Inc. (TSE: 4503, President and CEO: Yoshihiko Hatanaka, "Astellas"), and Seattle Genetics, Inc. (NASDAQ: SGEN) today announced dosing of the first patient in EV-103, a phase 1b clinical trial evaluating the safety and tolerability of enfortumab vedotin in combination with pembrolizumab or atezolizumab, two types of immune checkpoint inhibitor (CPI) therapies, for first- or second-line treatment of patients with locally advanced or metastatic urothelial cancer. Enfortumab vedotin is an investigational antibody-drug conjugate (ADC) designed to deliver the cell-killing agent monomethyl auristatin E (MMAE) to the target Nectin-4.

"The initiation of EV-103 is an important step in investigating the utility of enfortumab vedotin in earlier lines of therapy, including the first-line setting, for locally advanced and metastatic urothelial cancer, where patients ineligible for cisplatin-based chemotherapy continue to have limited treatment options," said Jonathan Drachman, M.D., Chief Medical Officer and Executive Vice President, Research and Development at Seattle Genetics. "This study represents Seattle Genetics' third ADC under clinical evaluation in combination with CPIs, highlighting our vision that ADCs could be the preferred partners for immuno-oncology agents for patients with solid tumors and hematological cancers."

The EV-103 study is a single arm, open label multicenter trial that will enroll up to 85 patients with locally advanced or metastatic urothelial cancer who are ineligible for first line cisplatin-based chemotherapy or have progressed following treatment with a regimen containing platinum-based chemotherapy. Enfortumab vedotin will be administered during weeks one and two of every three-week cycle, and pembrolizumab or atezolizumab will also be administered during week one of this period. The primary objective of the trial is to assess the safety and tolerability of enfortumab vedotin in combination with CPI therapy. Secondary endpoints include the recommended dose in combination with CPIs, overall response rate (ORR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS), among other measures.

"We are pleased to be moving forward with evaluating enfortumab vedotin in combination with CPI therapy, as we look to further investigate the potential of this agent in some of the hardest-to-treat cancers," said Steven Benner, M.D., Senior Vice President and Global Therapeutic Area Head, Oncology Development at Astellas. "Many patients do not respond to or relapse after treatment with CPIs, and we are committed to exploring additional ways to potentially address the unmet needs of the urothelial cancer community." 

Enfortumab vedotin is also being studied as monotherapy in a pivotal clinical trial for patients with advanced urothelial cancer who have received prior CPI therapy, called EV-201 (NCT03219333), to support potential registration under the U.S. Food and Drug Administration's (FDA) accelerated approval regulations.

For more information about the EV-103 clinical trial, please visit www.clinicaltrials.gov.

About Urothelial Cancer
Urothelial cancer is most commonly found in the bladder (90 percent). According to the American Cancer Society, approximately 79,000 people in the U.S. will be diagnosed with bladder cancer during 2017 and almost 17,000 will die from the disease. Outcomes are poor for patients diagnosed with metastatic disease, with a five-year survival rate of five percent.

About Enfortumab Vedotin
Enfortumab vedotin is an investigational ADC composed of an anti-Nectin-4 monoclonal antibody attached to a microtubule-disrupting agent, MMAE, using Seattle Genetics' proprietary, industry-leading linker technology. Enfortumab vedotin targets Nectin-4, a cell adhesion molecule identified as an ADC target by Astellas, which is expressed on many solid tumors.

About Astellas
Astellas Pharma Inc., based in Tokyo, Japan, is a company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceutical products. We focus on Urology, Oncology, Immunology, Nephrology and Neuroscience as prioritized therapeutic areas while advancing new therapeutic areas and discovery research leveraging new technologies/modalities. We are also creating new value by combining internal capabilities and external expertise in the medical/healthcare business. Astellas is on the forefront of healthcare change to turn innovative science into value for patients. For more information, please visit our website at https://www.astellas.com/en.

About Seattle Genetics
Seattle Genetics is an innovative biotechnology company dedicated to improving the lives of people with cancer through novel antibody-based therapies. The company's industry-leading antibody-drug conjugate (ADC) technology harnesses the targeting ability of antibodies to deliver cell-killing agents directly to cancer cells. Seattle Genetics commercializes ADCETRIS® (brentuximab vedotin) for the treatment of several types of CD30-expressing lymphomas. The company is also advancing a robust pipeline of novel therapies for solid tumors and blood-related cancers designed to address significant unmet medical needs and improve treatment outcomes for patients. More information can be found at www.seattlegenetics.com and follow @SeattleGenetics on Twitter.

About the Astellas and Seattle Genetics Collaboration
Astellas and Seattle Genetics entered into the ADC collaboration in January 2007 and expanded it in November 2009. Under the collaboration, the companies are co-developing and have options to globally co-commercialize enfortumab vedotin.

SOURCE: Seattle Genetics

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