Mirabegron (trade name Myrbetriq in the US and Betmiga in Europe) is a drug for the treatment of overactive bladder (OAB). It was developed by Astellas Pharma and was approved in the United States in July 2012. Originally developed as a treatment for diabetes, the development of mirabegron was later refocused to OAB. Mirabegron is an orally bioavailable agonist of the human beta-3 adrenergic receptor (ADRB3), with muscle relaxing, neuroprotective and potential antineoplastic activities. Upon oral administration, mirabegron binds to and activates ADRB3, which leads to smooth muscle relaxation. Mirabegron also restores sympathetic stimulation in mesenchymal stem cell (MSC) niches, inhibits JAK2-mutated hematopoietic stem cell (HSC) expansion and blocks the progression of myeloproliferative neoplasms (MPNs). Lack of sympathetic stimulation of the MSC and HSC niche is associated with the development of MPNs.