3 December 2019 - - US-based biotechnology company Seattle Genetics, Inc. (NASDAQ: SGEN) and Japan-based Astellas Pharma Inc. (TSX: 4503) have forged a clinical collaboration agreement with US-based Merck (NYSE: MRK) to evaluate the combination of Seattle Genetics' and Astellas' antibody-drug conjugate enfortumab vedotin and Merck's anti-PD-1 therapy, Keytruda (pembrolizumab), in patients with previously untreated metastatic urothelial cancer, the companies said.

Under the terms of the agreement, the three companies will conduct and fund a global, registrational phase 3 clinical trial to be led by Seattle Genetics.

The trial will be designed to evaluate the efficacy of the combination of enfortumab vedotin and pembrolizumab in patients with previously untreated locally advanced or metastatic urothelial cancer.

The companies are working in consultation with regulatory authorities to finalize the trial design and currently plan to initiate the trial in the first half of 2020.

Enfortumab vedotin is currently under review by the US Food and Drug Administration for the treatment of patients with locally advanced or metastatic urothelial cancer who have received a PD-1/L1 inhibitor and who have received a platinum-containing chemotherapy in the neoadjuvant/adjuvant, locally advanced or metastatic setting. The PDUFA action date is March 15, 2020.

Keytruda is a registered trademark of Merck Sharp and Dohme Corp., a subsidiary of Merck and Co., Inc., Kenilworth, NJ, USA.

Urothelial cancer is the most common type of bladder cancer (90% of cases).

In 2019, more than 80,000 people will be diagnosed with bladder cancer in the United States.

Globally, approximately 549,000 people were diagnosed with bladder cancer last year, and there were approximately 200,000 deaths worldwide.

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 linker technology.

Enfortumab vedotin targets Nectin-4, a cell adhesion molecule that is expressed on many solid tumors, and that has been identified as an ADC target by Astellas.

The safety and efficacy of enfortumab vedotin are under investigation and have not been established. There is no guarantee that the agent will receive regulatory approval or become commercially available for the uses being investigated.

Seattle Genetics 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.

The company is headquartered in Bothell, Washington, and has a European office in Switzerland.

Seattle Genetics and Astellas are co-developing enfortumab vedotin under a collaboration that was entered into in 2007 and expanded in 2009.

Under the collaboration, the companies are sharing costs and profits on a 50: 50 basis worldwide.