FDA Approves Ipsen's Sohonos (Palovarotene), First Therapy for 'Stone Man Syndrome'

▎Edited by the WuXi AppTec content team

Today, Ipsen announced that the U.S. FDA has approved Sohonos (palovarotene) for marketing to reduce the formation of new heterotopic ossification in patients with fibrodysplasia ossificans progressiva (FOP). The applicable population includes adult FOP patients, female pediatric patients aged 8 years and above, and male pediatric patients aged 10 years and above. The press release notedSohonos is the first FDA-approved drug for the treatment of FOP.

A common nickname for Progressive Muscle Ossification is "Stone Man Syndrome," meaning that as the disease progresses, a person becomes immobile like a stone. The main symptoms of this rare disease are that the originally soft and elastic muscles and connective tissues in the body become inflamed after minor injuries and turn into bone, locking joints that were originally freely movable into a fixed position. The locking of the elbow and knee joints will permanently fix the patient's arms and legs at a certain angle. The fusion of the jawbone joints will affect their ability to eat and speak, and the ossification of tissues around the rib cage will lead to breathing difficulties. For patients with this rare disease, even with the most meticulous protection, ossification continues to occur, eventually leading to the growth of a second skeleton within their bodies. Without disease-modifying treatment, current management is limited to palliative care. Ultimately, the median life expectancy of FOP patients will be reduced to 56 years due to respiratory issues and cardio-pulmonary failure.

Palovarotene is an orally administered selective retinoic acid receptor γ (RARγ) agonist.Retinoic acid receptor gamma is a key regulator in the retinoid signaling pathway for skeletal development and heterotopic ossification. Palovarotene is designed to mediate interactions among receptors, growth factors, and proteins within the retinoid signaling pathway to reduce the formation of new abnormal bone. It has previously received Breakthrough Therapy Designation and Priority Review status from the U.S. FDA.

This approval is based on the results of a Phase 3 clinical trial named MOVE. The 18-month trial data has already been published in the Journal of Bone and Mineral Research. The data shows,Compared with historical data from patients who did not receive other treatments outside of standard care, the volume of heterotopic ossification in patients in the palovarotene group was significantly reduced.