Cyclerion formed in April 2019 as a spinoff of Ironwood Pharmaceuticals. Its research revolved around therapies that stimulate sGC, or soluble guanylate cyclase, an enzyme that had already attracted interest from drugmakers as a target for heart and lung diseases. Cyclerion’s initial slate of drug programs sought to treat serious cardiovascular conditions, including heart failure, as well as neurological disorders and rare illnesses like sickle cell disease.