Summary: regulatory status in the United States and the European Union

The FDA approved Atebrioz (zilurgisertib) tablets on September 25, 2026, one day before the September 26, 2026 PDUFA target action date, to reduce the volume of total new heterotopic ossification in adults and pediatric patients aged 12 years and older with fibrodysplasia ossificans progressiva. The NDA had been accepted with Priority Review by May 2026 and was based on Cohort 1 of the Phase 2 PROGRESS study, whose primary endpoint did not reach statistical significance; the NDA was supported by secondary endpoints. Zilurgisertib holds FDA Fast Track and orphan drug designations, and the FDA issued a Rare Pediatric Disease Priority Review Voucher to Incyte at approval. Incyte developed zilurgisertib and licensed worldwide development and commercialization rights to Mirum Pharmaceuticals in April 2026. In the European Union, zilurgisertib received orphan designation EU/3/25/3119 on August 22, 2025, and a marketing authorization application is under review by the EMA. U.S. commercial availability is expected in October 2026.

FDA approval

“The U.S. Food and Drug Administration (FDA) has approved Atebrioz (zilurgisertib) tablets to reduce the volume of total new heterotopic ossification (bone formation outside the skeleton) in adults and pediatric patients 12 years and older with fibrodysplasia ossificans progressiva (FOP).” (opens the source at this quote in a new tab)

Field	Quoted record
Drug name	“Atebrioz”
Active ingredient	“zilurgisertib”
Approval date	“9/25/2026”
FDA-approved use on approval date	“To reduce the volume of total new heterotopic ossification in adults and pediatric patients 12 years and older with fibrodysplasia ossificans progressiva”

“Initial U.S. Approval: 2026” (opens the prescribing information at this quote)

Regulatory submission: NDA submitted by May 2026

“U.S. FDA accepted the New Drug Application (NDA) for zilurgisertib in FOP patients 12 years and older and granted Priority Review with a Prescription Drug User Fee Act (PDUFA) date of September 26, 2026.” (opens the source at this quote in a new tab)
“Results from the pivotal Phase 2 PROGRESS study in FOP formed the basis of the NDA filing for zilurgisertib; Incyte plans to present the results at an upcoming medical conference.” (opens the source at this quote in a new tab)

“The FDA has accepted for review Incyte’s NDA with a PDUFA date of September 26, 2026.” (opens the source at this quote in a new tab)

Launch: Anticipated in October 2026

“Atebrioz is expected to be commercially available in the U.S. in October, with eligible patients paying as little as $0 per month through MAP.” (opens the source at this quote in a new tab)

Primary endpoint of the pivotal study and the basis of the NDA

“In addition, while the NDA for zilurgisertib is supported by secondary endpoints, the pivotal study did not reach statistical significance on the primary endpoint.” (opens the source at this quote in a new tab)

“Atebrioz was approved based on data from Cohort 1 of the PROGRESS study evaluating zilurgisertib in adult and pediatric patients aged 12 years and older with FOP. Efficacy was established based on total new HO lesion volume.” (opens the source at this quote in a new tab)

Fast Track, Priority Review, and Orphan Drug designations

“Atebrioz received fast track, priority review and orphan drug designation for this indication.” (opens the source at this quote in a new tab)

“The FDA has granted Fast Track designation and orphan drug designation to zilurgisertib as a treatment for patients with FOP.” (opens the source at this quote in a new tab)

Breakthrough Therapy designation

No evidence found.

Rare Pediatric Disease Priority Review Voucher

“With this approval, the FDA also issued a Rare Pediatric Disease Priority Review Voucher (PRV) to Incyte. The voucher can be used for a subsequent drug application that would not otherwise qualify for a priority review.” (opens the source at this quote in a new tab)

License of worldwide rights from Incyte to Mirum Pharmaceuticals

“Atebrioz was developed by Incyte and licensed to Mirum Pharmaceuticals, Inc. for worldwide development and commercialization.” (opens the source at this quote in a new tab)

“In April 2026, the Company entered into a license agreement with Incyte Corporation, under which the Company obtained the right to develop and commercialize zilurgisertib. Zilurgisertib is an oral small molecule ALK2 inhibitor in development for the treatment of fibrodysplasia ossificans progressiva. The Company made an upfront payment of $16.0 million in April 2026. In addition, the Company is obligated to pay royalties in the mid-to-high single digit percentage range and additional regulatory milestones of up to $48.0 million, including $25.0 million upon FDA approval, and commercial milestones of up to $15.0 million.” (opens the source at this quote in a new tab)

“In April 2026, we entered into an exclusive license agreement with Mirum Pharmaceuticals, Inc. granting Mirum worldwide rights to zilurgisertib, an ALK2 inhibitor in development for fibrodysplasia ossificans progressiva. Under the terms of the agreement, we received an upfront payment and are eligible to receive a Priority Review Voucher, and additional development and regulatory milestone payments, as well as sales-based milestones and tiered royalties in the mid-to-high single digit percent range on worldwide net sales.” (opens the source at this quote in a new tab)

“Incyte will continue to lead the development of zilurgisertib through potential approval, while Mirum will assume commercialization responsibilities, if zilurgisertib is approved.” (opens the source at this quote in a new tab)

European Union orphan designation

“This medicine was designated as an orphan medicine for the treatment of fibrodysplasia ossificans progressiva in the European Union on 22 August 2025.” (opens the source at this quote in a new tab)

Designation field	Quoted record
Active substance	“zilurgisertib”
Intended use	“Treatment of fibrodysplasia ossificans progressiva”
Orphan designation status	“Positive”
EU designation number	“EU/3/25/3119”
Date of designation	“22/08/2025”
Sponsor	“Incyte Biosciences Distribution B.V.”

European Union marketing authorization application

“In the European Union, a marketing authorization application (MAA) for zilurgisertib is currently under review by the European Medicines Agency (EMA), supported by data from Cohort 1 (patients aged 12 years and older) of the PROGRESS study.” (opens the source at this quote in a new tab)

Ongoing development in children younger than 12 years

“The PROGRESS development program also continues to advance, with enrollment completed in Cohort 2 of children aged 6 to <12 years, and enrollment underway in Cohort 3 of children aged 2 to <12 years.” (opens the source at this quote in a new tab)

Compassionate use before approval

“However, individuals with FOP, ages 12 and over, living in the United States, may be able to use zilurgisertib through a new Compassionate Use Program opened by Mirum and Incyte.” (opens the source at this quote in a new tab)

Earlier development for anemia

“The oral, potent, and highly selective activin receptor-like kinase 2 (ALK2) inhibitor zilurgisertib (INCB000928) is in development as a treatment for fibrodysplasia ossificans progressiva (FOP), and for anemia due to myelofibrosis, myelodysplastic syndromes, and multiple myeloma.” (opens the source at this quote in a new tab)