Atebrioz

Budget impact modelIn development

Overview

Estimated change in the drug and administration spending of a United States health plan over 3 years when Atebrioz (zilurgisertib) is added to the treatments covered for members aged 12 years and older with fibrodysplasia ossificans progressiva (FOP).

Perspective

A United States health plan paying drug acquisition and drug administration costs for its members. Member cost sharing, manufacturer rebates, and patient assistance are excluded.

Time horizon

3 years, undiscounted

Price basis

Average annual list prices stated at launch for Sohonos (2023) and Pasatru (2026), and an analyst estimate for Atebrioz, whose list price had not been announced on 1 October 2026. Infusion administration is costed at the 2026 Medicare Physician Fee Schedule national payment.

Inputs checked

2026-10-01

Every field can be changed, and the results recalculate as it is. A field is marked with the basis of its value, which links to the quote, data row, or assumption behind it. PMPM is the cost per member per month.

Target population

Market share

Share of eligible patients on each treatment during each year. Supportive care alone takes whatever share the other rows leave. Assumption

Treatment costs

Cost per patient per year on treatment

Results

Budget impact by year

Budget impact by cost category

Patients on treatment and treatment cost, by treatment

Sensitivity analysis

One-way sensitivity analysis of the 3-year budget impact

Each input is set to its low and its high value in turn, with every other value as entered above. The 10 inputs that move the result most are shown; the vertical line marks the current result, +$254,821.

Scenario analyses

Inputs and sources

A value on a quoted source carries the quote as the evidence report holds it, linked to the document it came from. A value on published data names the row of the file it was read from. An assumption is a value no source states.

• Plan members

  1,000,000Assumption

  A plan of 1,000,000 members is the base case of the model. A plan enters its own enrollment.

• Prevalence of FOP

  0.088 per 100,000Range 0.05 per 100,000 to 0.139 per 100,000Quoted source

  The United States estimate of 0.88 per million is 0.088 per 100,000. The low bound is the often-cited 0.5 per million (0.05 per 100,000) and the high bound is the French national registry estimate of 1.39 per million (0.139 per 100,000). At the base case a plan of 1,000,000 members has 0.88 members with FOP.

  • “Taking into account the limitations described above, we report an estimated minimum prevalence of 0.88 per million individuals (1 in 1.14 million people) living in the United States.”

    SourcePignolo et al. (2021)

  • “This study suggests that the prevalence of FOP is higher than the often-cited value of 0.5 per million.”

    SourcePignolo et al. (2021)

  • “Based on the BNDMR, 94 individuals with FOP were alive on December 31, 2020. Thus, the prevalence was estimated at 1.39 per million (95% CI: 1.13-1.71).”

    SourceBaujat et al. (2026)

• Share with an established diagnosis

  100%Range 90% to 100%Assumption

  The United States prevalence estimate counts patients already identified through clinics, registries, and the patient association, so each counted patient has a diagnosis and the base case applies 100%. The low bound of 90% is the diagnosed share assumed in the palovarotene analysis submitted to CADTH.

  • “After deduplication, 373 unique patients were identified in the United States, 294 of whom who were not listed as deceased in any list.”

    SourcePignolo et al. (2021)

  • “The sponsor assumed that 90% of patients with FOP would be correctly diagnosed owing to difficulty in correctly diagnosing FOP.”

    SourceCADTH Pharmacoeconomic Review (2023)

• Share aged 12 years and older

  84.5%Range 79.9% to 89.1%Assumption

  No source reports the share aged 12 years and older. Of 284 United States patients with age data, 31 were under 10 years and 65 were 10 to under 20 years. Spreading the 65 evenly over the 10 years of that band places 13 of them at age 10 or 11, so 284 - 31 - 13 = 240 patients (84.5%) are 12 years or older. The high bound places none of the 65 under 12 years (253 of 284, 89.1%) and the low bound places 26 of them under 12 years (227 of 284, 79.9%).

  • “Of 284 patients with age data, the average age was 29.3 years; 31 (11%) were 0 to < 10 years, 65 (23%) were ≥ 10 to < 20 years, 63 (22%) were ≥ 20 to < 30 years, 58 (20%) were ≥ 30 to < 40 years, and 67 (24%) were ≥ 40 years.”

    SourcePignolo et al. (2021)

  • “ATEBRIOZ is indicated to reduce the volume of total new heterotopic ossification (HO) in adults and pediatric patients aged 12 years and older with fibrodysplasia ossificans progressiva (FOP).”

    SourceAtebrioz Prescribing Information (2026)

• Atebrioz drug cost per bottle of 120 tablets

  $61,602Range $51,253 to $114,990Assumption

  The list price had not been announced on 1 October 2026. The base case uses the analyst estimate of about $750,000 a year: $750,000 x 30 / 365.25 = $61,602 per 30-day bottle. The low bound is the Sohonos average list price ($624,000 x 30 / 365.25 = $51,253) and the high bound is the Pasatru average list price ($1,400,000 x 30 / 365.25 = $114,990). Replace this value with the wholesale acquisition cost per bottle once it is published.

  • “Citizens analyst Jonathan Wolleben estimates Atebrioz could cost about $750,000 annually and generate roughly $150 million in peak worldwide sales.”

    SourceReuters (2026)

  • “Mirum, which predicted peak sales of more than $200 million earlier this year for Atebrioz, has not yet revealed a list price and will announce the cost when it becomes available in October, Peetz said.”

    SourceBioSpace (2026)

• Days supplied by one Atebrioz bottle

  30 daysQuoted source

  The recommended dosage of 100 mg once daily is 4 tablets of 25 mg, so a bottle of 120 tablets supplies 120 / 4 = 30 days.

  • “The recommended dosage of ATEBRIOZ is 100 mg orally once daily with or without food”

    SourceAtebrioz Prescribing Information (2026)

  • “ATEBRIOZ contains 25 mg of zilurgisertib and is available as a round, white to off-white film-coated tablet debossed on one side with "INCY" and "25" on the other side in bottles of 120 tablets with child-resistant closure (NDC 79378-029-16). Dispense in a tight container (See USP).”

    SourceAtebrioz Prescribing Information (2026)

• Atebrioz adherence (share of days supplied)

  100%Range 80% to 100%Assumption

  No adherence data from clinical practice exist. All participants assigned to zilurgisertib in PROGRESS completed the 24-week treatment period, so the base case supplies the drug on 100% of days, which gives the highest drug cost. The low bound of 80% is the conventional threshold for adherence measured as the proportion of days covered.

  • “All patients in the zilurgisertib group completed treatment”

    SourcePignolo et al. (2026b)

• Sohonos drug cost per 30 days

  $51,253Range $41,002 to $61,504Quoted source

  The average list price of $624,000 a year, which covers daily dosing and flare-up dosing as used on average, is $624,000 x 30 / 365.25 = $51,253 per 30 days. The bounds are 20% below and above the base case, because the cost for one patient depends on the number of 12-week flare-up courses in a year.

  • “Ipsen will sell the medicine under the brand name Sohonos at an average list price of $624,000 a year, though the cost will vary depending on insurance coverage, patient needs and support programs.”

    SourceBioPharma Dive (2023)

• Days covered by the Sohonos cost

  30 daysAssumption

  The Sohonos price is published as an annual average with no pack price, so the model expresses it per 30 days, the same period as one Atebrioz bottle.

• Sohonos adherence (share of days supplied)

  100%Range 80% to 100%Assumption

  No adherence data from clinical practice exist. The base case supplies the drug on 100% of days, the same assumption as for Atebrioz, and the low bound of 80% is the conventional threshold for adherence measured as the proportion of days covered.

• Pasatru drug cost per infusion

  $107,324Range $53,125 to $160,986Quoted source

  The average annual list price of about $1.4 million, with one infusion every 4 weeks, is $1,400,000 x 28 / 365.25 = $107,324 per infusion. The bounds are the stated range for dosing at 3 or 10 mg per kilogram: $693,000 x 28 / 365.25 = $53,125 and $2,100,000 x 28 / 365.25 = $160,986.

  • “Pasatru will have an average annual, per-patient list price of about $1.4 million based on the enrollees in clinical studies, according to a Regeneron spokesperson. The drug is dosed at either 3 or 10 milligrams per kilogram of body weight, so the cost could total anywhere between $693,000 and $2.1 million, the spokesperson said.”

    SourceBioPharma Dive (2026)

• Days between Pasatru infusions

  28 daysQuoted source

  One infusion every 4 weeks is one infusion every 28 days.

  • “The recommended starting dosage of PASATRU is 10 mg/kg administered as an intravenous infusion over 60 minutes once every 4 weeks.”

    SourcePasatru Prescribing Information (2026)

• Pasatru share of scheduled infusions given

  100%Range 80% to 100%Assumption

  No data on missed infusions in clinical practice exist. The base case gives every scheduled infusion, and the low bound of 80% applies the same threshold used for the oral products.

• Administration cost per Pasatru infusion

  $133.27Range $67.14 to $266.54Published data

  The base case is the 2026 Medicare national non-facility payment for a 1-hour infusion of a complex biologic agent, CPT 96413: 3.99 total relative value units x the conversion factor of 33.4009 = $133.27. The low bound is the payment for a 1-hour therapeutic infusion, CPT 96365: 2.01 x 33.4009 = $67.14. The high bound is twice the base case, an assumption for a plan that pays more than the Medicare rate. No source states which code a payer accepts for Pasatru.

  • 2026, HCPCS 96413, Chemo iv infusion 1 hr: non-facility total RVU 3.99, conversion factor 33.4009

    SourceCMS Physician Fee Schedule relative value file (2026)

  • 2026, HCPCS 96365, Ther/proph/diag iv inf init: non-facility total RVU 2.01, conversion factor 33.4009

    SourceCMS Physician Fee Schedule relative value file (2026)

• Market share

  Assumption

  No source reports the share of United States patients on each product, so every share is an assumption. Sohonos is held at 8% without Atebrioz: North America sales of 11.6 million euros in 2025 are about 13.1 million dollars at 1.13 dollars per euro (an assumed 2025 average rate), which is 21 patient-years at the list price of $624,000, and 21 of the 254 United States patients aged 12 years and older (300 x 84.5%) is 8.3%. Pasatru, approved in August 2026 for adults, is assumed at 5%, 10%, and 15% in years 1 to 3. Atebrioz is assumed at 15%, 25%, and 30%; with the other two products, 44% of eligible patients receive a disease-modifying drug in year 3, close to the 45% uptake by year 3 in the palovarotene analysis submitted to CADTH. Of the Atebrioz share, 2, 3, and 4 points are taken from Sohonos, 1, 3, and 5 points from Pasatru, and 12, 19, and 21 points from supportive care alone, reflecting the reported clinician expectation that patients will prefer a daily oral product to a monthly infusion.

  • “we actually estimate there were more [FOP] patients on clinical studies than on commercial drugs. Which we take as a real statement”

    SourceFierce Pharma (2026)

  • “Sohonos: flat sales impacted by limited number of new patients in the U.S.”

    SourceIpsen (2026)

  • Sohonos sales, North America, million euros: full year 2025, 11.6; full year 2024, 14.1

    SourceIpsen (2026)

  • “35% / 40% / 45%”

    SourceCADTH Pharmacoeconomic Review (2023)

  • “The sponsor compared a reference scenario in which patients received SoC alone to a new drug scenario in which palovarotene was reimbursed as an add-on therapy to SoC, with palovarotene plus SoC assumed to capture 45% of the total market share by year 3, based on the sponsor’s internal estimates and expert opinion.”

    SourceCADTH Pharmacoeconomic Review (2023)

  • “Leerink Partners estimates there are about 300 FOP patients in the U.S. Analyst Joseph Schwartz said in a research note that diagnosis rates for the disorder could rise as new therapies create awareness of the disease and genetic testing increases. He added that clinicians have told Leerink that that they expect patients will prefer Atebrioz’s daily oral formulation versus monthly infusions of Regeneron’s drug.”

    SourceMedCity News (2026)

Methods and limitations

Methods

• The model is prevalence-based. The patient funnel gives the number of plan members aged 12 years and older with FOP, and each share is the fraction of those members on a treatment during a model year. A member on a treatment is costed for the 12 months of that year.
• Year 1 is the first 12 months in which Atebrioz is available, expected to begin in October 2026. The eligible population is held constant over the 3 years because no source reports an annual rate of new diagnoses or of mortality in FOP.
• Two mixes are costed: one in which eligible members receive Sohonos, Pasatru, or supportive care alone, and one in which Atebrioz is also covered. The budget impact is the cost of the second mix minus the cost of the first, reported per year, per member per month, and per member per year. Costs are undiscounted.
• Costs counted are drug acquisition at list price and, for Pasatru, administration of one intravenous infusion every 4 weeks. Supportive care (glucocorticoids and nonsteroidal anti-inflammatory drugs for flare-ups) is given with every treatment and is excluded as common to both mixes.
• A plan of 1,000,000 members expects fewer than 1 eligible member, so every result is an expected value across many plans of that size. A plan with 1 eligible member on Atebrioz for a year pays the full annual cost of about $750,000 at the base case price, which is $0.0625 per member per month.

Limitations

• The Atebrioz list price had not been announced on 1 October 2026, and the base case price is an analyst estimate. The result changes in direct proportion to this value.
• Market shares are assumptions. No source reports the number of United States patients on Sohonos or Pasatru, and Pasatru had been available for about 1 month when the model was written.
• List prices are used for all three products. Confidential rebates, statutory Medicaid rebates, and member cost sharing would lower the plan's net cost and are excluded.
• Pasatru is indicated for adults and Sohonos for females aged 8 years and older and males aged 10 years and older; the model applies one mix to all members aged 12 years and older and does not model adolescents and adults separately.
• Medical costs that treatment may change, such as hospital admissions for flare-ups, are excluded because no source reports United States per-patient medical costs in FOP or the effect of any product on them.
• Monitoring costs are excluded: the skeletal maturity radiographs recommended for growing children on Sohonos, and the pregnancy test before Atebrioz is started.
• Members receiving a product through a clinical trial or its open-label extension are supplied by the sponsor, and the model does not subtract them from the eligible population.