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Sohonos
Published
Product name
Sohonos
Active ingredient
Palovarotene
Submission type
New chemical entity
Decision
Approved
Decision date
Registration date
What this medicine was approved for
Sohonos (palovarotene) was approved for the following therapeutic use:
Sohonos is indicated to reduce the formation of heterotopic ossification in adults and children aged 8 years and above for females and 10 years and above for males with fibrodysplasia ossificans progressiva (FOP).
How this medicine works
Palovarotene is a retinoic acid receptor gamma (RARγ) selective agonist. Fibrodysplasia ossificans progressiva (FOP, formerly referred as myositis ossificans progressiva) is a genetic condition caused by a gain-of-function mutation in the gene encoding activin A receptor type 1 (also known as activin receptor-like kinase 2), a bone morphogenetic protein (BMP) expressed by chondrocytes and osteoblasts. The mutant protein aberrantly activates the Smad1/5/8 signalling pathway, diverting mesenchymal progenitor cells from a soft tissue fate (allowing for normal tissue repair) to an osseous fate (promoting chondrogenesis and heterotopic bone formation).
RARγ is expressed in chondrogenic cells and chondrocytes, where it operates as an unliganded transcriptional repressor. Activation of RARγ downregulates BMP signalling by reducing phosphorylation of downstream effectors Smad1/5/8. In this way, palovarotene prevents chondrogenesis and heterotopic ossification in FOP, and enables normal muscle tissue repair or regeneration to take place, reducing damage to muscle tissue.
Why the TGA approved or did not approve this medicine
The decision was based on quality (chemistry and manufacturing), nonclinical (pharmacology and toxicology), clinical (pharmacology, safety and efficacy) and risk management plan information submitted by the sponsor. The benefit-risk profile of Sohonos was considered favourable for the therapeutic use approved.
Sponsor