Rhythm Pharmaceuticals Inc., a company developing medicines for rare genetic disorders of obesity, has won FDA approval for its first product, Imcivree (setmelanotide), following a priority review. The drug is designed to restore a biological pathway that, when disrupted, can lead to constant hunger. The approval covers the treatment of three types of ultrarare early onset obesity tied to pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1) and leptin receptor (LEPR) deficiencies, when confirmed by genetic testing.