Seattle Genetics, a Bothell, Wash.-based biotech focused on monoclonal antibody-based therapies for the treatment of cancer, has expanded its antibody-drug conjugate (ADC) collaboration with Abbott Laboratories, a global healthcare company.

Abbott will pay an upfront fee of $25 million for rights to utilize Seattle Genetics' auristatin-based ADC technology with antibodies to additional oncology targets. In addition, Seattle Genetics may receive up to $220 million in potential milestone payments per additional target upon achieving predetermined development and commercial objectives, as well as mid-to-high single-digit royalties on worldwide net sales of any resulting products under the multi-target collaboration.

"ADCs have emerged as an important therapeutic approach to cancer, driven by the FDA approval of Adcetris, and encouraging data from numerous clinical and preclinical ADC programs in development by Seattle Genetics and our collaborators," said Natasha Hernday, vice president, corporate development, Seattle Genetics.

ADCs are monoclonal antibodies that are designed to selectively deliver cytotoxic agents to tumor cells. Seattle Genetics has developed proprietary technology employing synthetic cytotoxic agents, such as monomethyl auristatin E (MMAE) and monomethyl auristatin F (MMAF), and stable linker systems that attach these cytotoxic agents to the antibody. Seattle Genetics' linker systems are designed to be stable in the bloodstream and release the potent cell-killing agent once inside targeted cancer cells. This approach is intended to spare non-targeted cells and thus reduce many of the toxic effects of traditional chemotherapy while enhancing antitumor activity

Seattle Genetics and Abbott originally entered into an ADC collaboration in March 2011 under which Abbott paid an upfront fee of $8 million for rights to utilize Seattle Genetics' ADC technology with antibodies to a single oncology target. Abbott is responsible for research, product development, manufacturing and commercialization of any ADC products under the expanded collaboration. In addition to the upfront payment and potential milestone payments and royalties, Seattle Genetics will receive annual maintenance fees and research support payments for assistance provided to Abbott under the collaboration.