Milner serves as Executive Chairman of Armetheon, a specialty biopharmaceutical company developing novel small molecule drugs for cardiovascular diseases. He has been CEO of Heart Metabolics Limited UK (now HMBL) since 2011 and was also CEO of Heart Metabolics Limited Ireland from 2014 till 2015. During this time, initially at the UK and then at the Irish company, he developed perhexiline maleate as an orphan drug treatment for hypertrophic cardiomyopathy (HCM). In 1997, Milner co-founded ARYx Therapeutics, where he served as CEO until 2005 and as president from 2005 to 2010, with overall responsibility for R&D. In 1990, he co-founded CV Therapeutics, where, as a member of senior management from 1992 to 1996, he in-licensed and co-invented several successful pharmaceuticals. CV Therapeutics was acquired by Gilead for $1.5 billion in cash in 2009. In 2005, Milner was instrumental in restructuring his family pharmaceutical company ML Laboratories and its subsequent merger to form Vectura, a profitable company and one of the worlds leading makers of inhaled products.
Prior to 1992, Milner was as an assistant professor of medicine at Washington University in St. Louis. His research led to the discovery of pleiotrophin (PTN), a novel growth factor that regulates stem cell differentiation, organ development, and the epithelial mesenchymal transition (EMT). He was educated at the University of Liverpool receiving his medical degree in 1980, before completing his postgraduate training at the Johns Hopkins Hospital, the University of Virginia and Washington University in St. Louis. Milner is co-inventor on 50 issued patents, and an author of 29 original scientific articles in science, biochemistry, circulation, cancer, JCI and JBC. He is a fellow of the American College of Cardiology (FACC), and a board certified physician and cardiologist. He also serves as adjunct clinical faculty at Stanford University School of Medicine.