Addenda Pharmaceuticals

Addenda Pharmaceuticals was a biotechnology company focused on the development of targeted radiopharmaceuticals for the treatment of cancer. The company specialized in utilizing alpha-emitting isotopes, specifically Actinium-225, to create potent and precise therapies for solid tumors. Founded by industry veterans Ken Song and Bill Rastetter, Addenda developed a pipeline of radioligand therapies targeting validated oncology markers such as SSTR2 and GPC3. In August 2020, the company was acquired by RayzeBio, forming the core of its radiopharmaceutical portfolio. RayzeBio subsequently advanced these programs into late-stage clinical trials before being acquired by Bristol Myers Squibb in 2024 for $4.1 billion. Addenda's technology represents a significant advancement in the field of targeted radiation therapy.