Seattle Genetics, Inc. (NASDAQ:SGEN) and Agensys, Inc., an affiliate of Tokyo-based Astellas Pharma Inc. (Tokyo:4503), today announced that Seattle Genetics has exercised an option to co-develop an additional antibody-drug conjugate (ADC) under the companies’ existing ADC collaboration agreement. The ADC, called ASG-15ME, targets the tumor antigen SLITRK6, which is known to be expressed on bladder and lung cancer. Agensys has submitted an investigational new drug (IND) application to the U.S. Food and Drug Administration (FDA) for a phase 1 trial of ASG-15ME. “Through our collaboration and co-development agreements with companies like Agensys/Astellas, Seattle Genetics continues to enhance its ability to innovate by combining our industry-leading ADC technology with proprietary cancer targets and antibodies to develop potential new treatments for patients with cancer,” said Eric L. Dobmeier, Chief Operating Officer of Seattle Genetics. “ADCs represent a novel therapeutic approach, and through our pipeline and collaborations more than half of the ADC candidates in clinical development utilize our technology. We look forward to working with Agensys/Astellas to advance ASG-15ME.” “We’re eager to continue our strong collaboration with Seattle Genetics for ASG-15ME,” said David Stover, Ph.D., Senior Vice President, Agensys Site Head. “This collaboration with Seattle Genetics is in line with our goal to utilize the most advanced technologies to generate more innovative medicines in oncology.” ASG-15ME is an ADC composed of a fully human antibody directed to SLITRK6, an antigen expressed in multiple solid tumors. Preclinically, ASG-15ME has demonstrated antitumor activity in models of bladder and lung cancer. The antibody is attached to a potent, synthetic cytotoxic agent, monomethyl auristatin E (MMAE), via an enzyme-cleavable linker using Seattle Genetics’ proprietary technology. The ADC is designed to be stable in the bloodstream, but to release MMAE upon internalization into SLITRK6-expressing tumor cells, resulting in targeted cell-killing. Upon the option exercise, Seattle Genetics will make an option exercise payment and thereafter fund half of the future development costs for the ASG-15ME program. The impact of the option exercise on Astellas’ current fiscal year (from April 1, 2013, to March 31, 2014) financial forecast will be immaterial.