Palovarotene is in clinical development for episodic use in the prevention of heterotopic ossification (HO) in patients with fibrodysplasia ossificans progressiva (FOP). FOP is a disabling condition, caused by the formation of bony bars within the muscles of the body (HO). This bone formation is usually first noticed in early childhood as a series of hard lumps in the neck or along the spine. These lumps, which may be tender, gradually shrink in size as the affected muscles are replaced by bone. The appearance of bony lumps in muscles is usually spontaneous but can also be provoked by any injury to the muscles.
Palovarotene is an oral, once-daily medicine which attaches to a receptor in cells, called the retinoic acid receptor gamma, switching on processes that reduce bone formation. If licensed, palovarotene has the potential to prevent HO in patients with FOP, a condition for which the only available treatments are for symptomatic relief.
The active substance in tofacitinib works by blocking the action of enzymes (proteins) known as Janus kinases. These enzymes play an important role in the process of inflammation that occurs in rheumatoid, psoriatic arthritis and ulcerative colitis. By blocking the enzymes’ action, tofacitinib helps reduce the inflammation and other symptoms of these diseases. Tofacitinib is administered orally. If licensed, tofacitinib would offer an additional treatment option for patients with active AS, who have responded inadequately to conventional therapy.