U.S. FDA Approves Palovarotene Capsules as a Treatment for FOP


SohonosTM is the first-ever treatment for people living with FOP in the United States

Today is a monumental day for the FOP community! 

Ipsen’s palovarotene capsules are now the first drug approved in the United States to treat fibrodysplasia ossificans progressiva (FOP) by the U.S. Food & Drug Administration (FDA).

You can read Ipsen’s press release and see the label information here.

  • The brand name of the drug is SohonosTM
  • The label for Sohonos indicates it may be prescribed to treat FOP in adults and children aged 8 years and above for females and 10 years and above for males
  • People with FOP and their families should discuss all potential side effects with their prescribing doctor. If your doctor is not comfortable advising on this recently available treatment, we encourage you to refer them to the International Clinical Council on FOP for further consultation. 


We are grateful to every FOP family that participated in the Ipsen studies and trials, this includes the FOP Natural History Study and the MOVE trial. Whether you feel the drug was effective for you or not, your contribution was important. We also acknowledge that some families experienced very serious side effects; your sacrifice will always be remembered. To the FOP families from around the world who made their voices heard by providing written or verbal testimony during the FDA Advisory Committee Meeting, thank you for your contributions as well.

We're also grateful to the Principal Investigators, Study Coordinators. and all of the staff at the trial sites that took such good care of our families. We also stop today and appreciate the researchers whose basic and translational research identified retinoids (e.g. palovarotene) as a potential treatment for FOP. Finally, we express our gratitude to both Clementia and Ipsen and their team members for their commitment to the FOP community and their tremendous investments in the development of palovarotene.

Where is SohonosTM Approved?

It is important to note that the FDA’s approval of Sohonos only extends to eligible patients with FOP living in the United States. In January 2022, Health Canada approved palovarotene capsules for eligible patients with FOP living in Canada. The only other country where palovarotene is currently approved is the United Arab Emirates which extends provisional approval to a drug that has been approved by another regulatory agency.

In What Other Countries is Ipsen Seeking Approval of Palovarotene?

Ipsen is in ongoing discussions with regulatory authorities in various countries about the approval of palovarotene capsules. At this time, that list is not public information. We await announcements from Ipsen and will share them with the FOP community when they are publicly available. 

Why Did the FDA Approve Palovarotene Capsules and the European Commission Did Not?

You may remember that on July 19 the European Commission ratified the decision of the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) and did NOT grant marketing authorization approval for palovarotene capsules. In Ipsen’s MOVE trial, the first analysis of trial data showed that palovarotene didn’t reduce bone formation. However, when Ipsen re-analyzed the data using other statistical approaches (a method called post-hoc analyses), the data showed palovarotene was effective in reducing bone formation.1

The U.S. FDA has a practice of doing its own analysis of the trial data that pharmaceutical companies bring to them. When reviewing Ipsen’s submission, the FDA found a similar result to Ipsen’s ad-hoc analysis which likely influenced their approval. The EMA’s CHMP does not do its own analysis of trial data which may be part of the reason they chose not to approve palovarotene.

On January 18, 2023, Ipsen released a Plain Language Summary of the Phase 3 MOVE Trial results as a way to provide greater understanding for people with FOP and their families. You can read the Plain Language Summary here.

What Other Drugs Are in Clinical Trials for FOP?

What we know about drug development is that not every drug works the same for every person. As the announcements about palovarotene are made, you will hear some people say they felt it worked for them and others who felt it wasn’t effective or felt the side effects (or the risk of the side effects) weren’t worth continuing to take the drug.

While we are grateful that palovarotene has received marketing authorization approval in several countries, we are also grateful that patients have the opportunity to participate in clinical trials to test other drugs for FOPThere are currently 4 active phase 2 and 3 trials for drugs to treat FOP and we are seeing pharmaceutical companies bring drug trials to countries that have never had them before. If you have a local physician who might be interested in running an FOP trial, please contact us at [email protected].

FOP experts often say it will likely take a cocktail of drugs to treat FOP. It is critically important that the trials are filled with the required number of eligible FOP patients so that the safety and effectiveness of all of these drugs can be determined. We urge each person living with FOP to review the list of trials and locations and speak with their doctor or the Principal Investigator to see what might be available to them.

Some of the benefits of participating in a clinical trial include:

  • After the placebo period, you will receive the drug if the trial offers an open-label extended treatment period.
  • Regular visits with an FOP expert during the duration of a trial.
  • There is no cost for you to participate in a trial as the travel expenses of you and a caregiver are covered. These expenses include airfare or train, lodging, car service and a food allowance. If you don’t have a caregiver available to travel with you, one may be provided for you in some trials.
  • It is important to remember that clinical trials are not treatments. They are tests of potential drugs to treat FOP so you should discuss all potential risks and benefits with your doctor or the trial’s Principal Investigator.

For those living in the European Union where palovarotene won’t be available to be prescribed, participating in one of these trials may be your next best option and you will want to enroll before the available spots fill. Please consult your doctor or Principal Investigator to discuss your options.

For those in Canada or the United States, even though palovarotene has been approved, you may choose to forgo the approved treatment and participate in a drug trial where participants are needed and there is no cost to you to participate. Of note, you cannot take Sohonos and participate in a clinical trial at the same time because the investigators won’t know which drug is (or isn’t) working for you.

Here is a list of the 4 remaining drug trials; 3 of which are recruiting. The links below will take you to more information about each trial.

If you have questions about participating in a clinical trial, the IFOPA has created a set of frequently asked questions that you can read at ifopa.org/fop_faq.

In just 16 years (2006-2022), the FOP community has moved from the discovery of the gene that causes FOP to the approval of the first drug to treat FOP in Canada. Today we have not only seen the first drug to treat FOP approved in the United States, but we are also watching 4 other drugs progress through phase 2 and 3 trials. We are grateful to those who have participated in clinical studies and trials and hope that as trials expand worldwide each person living with FOP will explore their options.

If you live in a country where there is not a clinical trial or perhaps you are not eligible to participate based on your age or your FOP progression, you are still eligible to participate in critical FOP research through the FOP Registry. You can sign up at fopregistry.org. After you complete an Enrollment Survey, you’ll be emailed a reminder to complete a Follow-Up Survey every 6 months. The Registry is available in English, French, German, Italian, Korean, Polish, Portuguese, Russian and Spanish. As a thank you for your participation, you’ll receive a $25 Visa Gift Card for each completed survey (some exclusions apply). Not sure if you’re already enrolled or have questions about the Registry? Email Sammi Kile, Real-World Evidence Manager, at [email protected].

It is important to note that you can still continue to participate in the FOP Registry even if you are in a clinical trial. Thank you to the extra special people who participate in both! 

We are thrilled to celebrate this important drug approval milestone with you today. We are in this fight to end FOP with each of you for as long as it takes! Thank you for being our partner whether you are an FOP family, donor, fundraiser, researcher, clinician, or pharmaceutical company team member.




Megan Olsen
FOP Mom and IFOPA Board Chair

Michelle Davis
IFOPA Executive Director

1 STAT News, 14 August 2023, “FOP Patients Plead for FDA Approval of Drug Despite Muddled Data

Read the International Clinical Council on FOP's Statement on FOP

Read letter shared by Ipsen CEO David Loew with the FOP community

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