AbbVie (ABBV) and ADARx Pharmaceuticals said Wednesday they signed a collaboration and license option agreement to develop small interfering RNA, or siRNA, therapeutics for several disease areas including neuroscience, immunology and oncology.

Under the terms of the deal, ADARx will get a $335 million upfront payment and is eligible to receive "several billion dollars" in contingent payments including option-related fees, milestone payments, and royalties, the companies said.

The collaboration will leverage ADARx's RNA technology together with AbbVie's know-how in antibody engineering, antibody drug conjugates and tissue delivery approaches to advance siRNA therapies.