Palovarotene (R-667, RO-3300074) was developed by Roche Holding AG as a selective retinoic acid receptor gamma agonist for the treatment of emphysema. Phase I clinical trials of palovarotene in patients with emphysema demonstrated that the drug is well tolerated, with improvements observed in markers of emphysema progression. Unlike all-trans retinoic acid, the pharmacokinetic profile of palovarotene appears to be dose-proportional. However, those studies were discontinued. Palovarotene is also being investigated in phase II of the clinical trial in the treatment of Fibrodysplasia Ossificans Progressiva (FOP). Palovarotene received Fast Track designation from the U.S. Food and Drug Administration (FDA) and orphan designations for the treatment of FOP from both the FDA and the European Medicines Agency (EMA).