Merck and Karo Bio have a collaboration in the field of estrogen receptors. Estrogen receptors are important targets for several diseases in the field of women's health but also inflammatory diseases and cancer. The joint drug discovery phase concluded in 2002, with Merck responsible for development of selected compounds. The candidate compound from the collaboration that entered Phase I clinical development in 2006 has been discontinued. A backup compound has been selected for preclinical development.