Last reviewed 2026-05-22 · How we verify

Sohonos (PALOVAROTENE)

Sohonos (generic name: PALOVAROTENE) is a Retinoid [EPC] Small molecule drug developed by Ipsen. It is currently FDA-approved (first approved 2023) for Progressive myositis ossificans.

Sohonos works by blocking the activity of a specific receptor that helps control bone growth.

Sohonos, also known as Palovarotene, is a small molecule that acts as an agonist of the retinoic acid receptor gamma. It is classified as a retinoic acid receptor gamma agonist, which is its mechanism of action.

At a glance

Mechanism of action

In patients with FOP, abnormal bone formation, including heterotrophic ossification (HO), is driven by gain-of-function mutation in the bone morphogenetic protein (BMP) type receptor ALK2 (ACVR1). Palovarotene is an orally bioavailable retinoic acid receptor agonist, with particular selectivity at the gamma subtype of RAR. Through binding to RAR, palovarotene decreases the BMP/ALK2 downstream signaling pathway by inhibiting the phosphorylation of SMAD1/5/8, which reduces ALK2/SMAD-dependent chondrogenesis and osteocyte differentiation resulting in reduced endochondral bone formation.

Approved indications

• Progressive myositis ossificans

Boxed warnings

• WARNING: EMBRYO-FETAL TOXICITY and PREMATURE EPIPHYSEAL CLOSURE IN GROWING PEDIATRIC PATIENTS WARNING: EMBRYO-FETAL TOXICITY and PREMATURE EPIPHYSEAL CLOSURE IN GROWING PEDIATRIC PATIENTS See full prescribing information for complete boxed warning. SOHONOS is contraindicated in pregnancy ( 5.1 , 8.1 ) Because of the risk of teratogenicity and to minimize fetal exposure, SOHONOS is to be administered only if conditions for pregnancy prevention are met ( 5.1 , 8.1 ) SOHONOS causes premature epiphyseal closure in growing pediatric patients with FOP, close monitoring is recommended ( 5.2 , 8.4 ) Embryo-Fetal Toxicity SOHONOS is contraindicated in pregnancy. SOHONOS may cause fetal harm. Because of the risk of teratogenicity and to minimize fetal exposure, SOHONOS is to be administered only if conditions for pregnancy prevention are met [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1) ]. Premature Epiphyseal Closure Premature epiphyseal closure occurs in growing pediatric patients treated with SOHONOS, close monitoring is recommended [see Warnings and Precautions (5.2) and Use in Specific Populations (8.4) ] .

Common side effects

• Dry skin
• Lip dry
• Arthralgia
• Pruritus
• Pain in extremity
• Rash
• Alopecia
• Erythema
• Headache
• Back pain
• Skin exfoliation
• Nausea

Key clinical trials

• A Study to Document and to Further Describe Long-term Safety and Effectiveness of Palovarotene in Participants With Fibrodysplasia Ossificans Progressiva (FOP)
• A Study of the Blood Levels of Palovarotene in Participants With Abnormal Liver Function Compared to Healthy Adult Participants After Intake of a Single Dose (PHASE1)
• A Rollover Study to Further Evaluate the Safety and Efficacy of Palovarotene Capsules in Male and Female Participants Aged ≥14 Years With Fibrodysplasia Ossificans Progressiva (FOP) Who Have Completed the Relevant Parent Studies. (PHASE3)
• An Open-Label Extension Study of Palovarotene Treatment in Fibrodysplasia Ossificans Progressiva (FOP) (PHASE2)
• An Efficacy and Safety Study of Palovarotene for the Treatment of Fibrodysplasia Ossificans Progressiva. (PHASE3)
• An Efficacy and Safety Study of Palovarotene for the Treatment of MO (PHASE2)
• Study to Compare the Pharmacokinetics, Safety, and Tolerability Following Administration of Palovarotene in Healthy Japanese and Non-Asian Subjects (PHASE1)
• Study Evaluating the Effect of Food on the Pharmacokinetics of Palovarotene and the Effect of Palovarotene on the Pharmacokinetics of the CYP3A4 Substrate Midazolam in Two Cohorts of Healthy Adult Subjects (PHASE1)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Sohonos CI brief — competitive landscape report
• Sohonos updates RSS · CI watch RSS
• Ipsen portfolio CI

Frequently asked questions about Sohonos

Related

• Drug class: All Retinoid [EPC] drugs
• Target: All drugs targeting Retinoic acid receptor gamma
• Manufacturer: Ipsen — full pipeline
• Therapeutic area: All drugs in Bone
• Indication: Drugs for Progressive myositis ossificans

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing