Agensys and Seattle Genetics initiate ASG-5ME phase I clinical trial for castration-resistant prostate cancer

Agensys, Inc., an affiliate of Tokyo-based Astellas Pharma Inc., and Seattle Genetics, Inc. (Nasdaq:SGEN) today announced that they have initiated a phase I clinical trial of ASG-5ME for the treatment of castration-resistant prostate cancer. ASG-5ME is an antibody-drug conjugate (ADC) targeting the SLC44A4 antigen and is being co-developed by both companies for the treatment of solid tumors.

"There is significant need for new prostate cancer therapies, given that more than 32,000 men are expected to die of prostate cancer in 2010," said Leonard Reyno, M.D., Senior Vice President and Chief Medical Officer at Agensys. "We believe ASG-5ME, which is an ADC designed to deliver the potent cytotoxic agent MMAE directly to tumor cells, has the potential to provide a new therapeutic option for men with advanced prostate cancer."

"This clinical trial, together with our ongoing phase I trial of ASG-5ME for pancreatic cancer, reflects continued progress in expanding our pipeline of clinical-stage ADCs for cancer," said Jonathan Drachman, M.D., Senior Vice President, Research and Translational Medicine of Seattle Genetics.

The single-agent phase I trial will evaluate the safety, tolerability, pharmacokinetic profile and antitumor activity of escalating doses of ASG-5ME. The study is designed to enroll up to 60 patients at multiple centers in the United States.

ASG-5ME is an ADC composed of a fully human antibody directed to SLC44A4, a solute carrier antigen family member identified by Agensys to be overexpressed in epithelial cancers, including more than 80 percent of samples derived from patients with prostate, pancreatic and gastric cancers. The antibody is attached to a potent, synthetic cell-killing 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 SLC44A4-expressing tumor cells, resulting in targeted cell-killing. Preclinically, ASG-5ME has demonstrated potent antitumor activity, inducing regressions in models of established prostate, pancreatic and colon cancers.