Seattle Genetics, Inc. announced that Genentech, Inc. has designated additional antigen targets under the parties' existing antibody-drug conjugate (ADC) collaboration agreement. Under the terms of the agreement, Genentech has rights to use Seattle Genetics' ADC technology with antibodies against multiple targets selected by Genentech. To secure exclusive access to the additional targets, Genentech has paid a fee of $3.0 million and purchased $7.0 million of Seattle Genetics common stock.

"We are pleased to expand our ongoing collaboration with Genentech," stated Clay B Siegall, PhD, president and CEO of Seattle Genetics. "We have made significant progress with our ADC platform, demonstrating improved stability of the linker system and increased potency of the drug payload compared to existing drug conjugate technologies. Our ADC technology allows us and our partners to develop therapeutics designed to deliver antitumour drugs directly to target cells, minimizing the dose-limiting toxicity of conventional anti-cancer treatments."

Seattle Genetics and Genentech established their ADC collaboration in April 2002, at which time Genentech paid an upfront fee and made an equity investment in Seattle Genetics in exchange for access to an initial number of target antigens. Genentech also pays ongoing research and material supply fees and has agreed to pay progress-dependent milestone payments and royalties on net sales of any resulting ADC products. Genentech is responsible for research, product development, manufacturing and commercialization of any products resulting from the collaboration.

ADCs utilize the targeting ability of monoclonal antibodies to deliver potent, cell-killing payloads to specific cells. Seattle Genetics has developed novel second-generation ADC technology employing synthetic, highly potent drugs that can be attached to antibodies through proprietary linker systems. The linkers are designed to be stable in the bloodstream but to release the drug payload under specific conditions once inside target cells, thereby sparing non-target cells many of the toxic effects of traditional chemotherapy. ADCs may increase the therapeutic potential of antibodies with targeting ability but that have no inherent cell-killing activity on their own.

Seattle Genetics discovers and develops monoclonal antibody-based therapeutics to treat cancer and other human diseases. The company has built a diverse portfolio of product candidates targeted to many types of cancer, including two being tested in multiple ongoing clinical trials, SGN-30 and SGN-15, and three in preclinical development, SGN-40, SGN-35 and SGN-17/19. The product candidates encompass three platform technologies: genetically engineered monoclonal antibodies, antibody-drug conjugates (ADCs) and antibody-directed enzyme prodrug therapy (ADEPT). Seattle Genetics has developed leading ADC technology comprised of highly potent synthetic drugs and stable linkers for attaching the drugs to monoclonal antibodies. The company currently has license agreements for its ADC technology with Genentech, Celltech Group and Protein Design Labs.