Prescribing guide
Atebrioz (zilurgisertib)Dosing, pregnancy verification, CYP3A4 and MATE interactions, and prior authorization for fibrodysplasia ossificans progressivaFor prescribers and their offices treating fibrodysplasia ossificans progressiva: what the pharmacy needs before it ships, what the prior authorization wants documented, the titration and the monitoring the label requires.
Dispensing gate
No REMS; verify no pregnancy in females of reproductive potential, reconcile strong CYP3A4 inhibitors, CYP3A4 inducers and MATE1 or MATE2-K substrates, fax the MAP Patient Enrollment Form with both sides of the insurance card to 1-855-282-4884, and the MAP pharmacy confirms shipping before the first bottle.
Example PA threshold
No public payer policy found as of November 9, 2026; Mirum's checklist for plans without a policy: genetic test results, CT or MRI, chart notes on HO volume and location, CAJIS and flares, FOP drug history, and an endocrinologist, rheumatologist, geneticist, orthopedic or bone specialist.
Monitoring
No scheduled labs in the label; pregnancy status before initiation, contraception through 1 week after the final dose, and review of any new CYP3A4 inhibitor, CYP3A4 inducer or MATE substrate.
Support line
Mirum Access Plus, 1-855-676-4968 (1-855-MRM-4YOU), Monday to Friday 8 AM to 8 PM Eastern, enrollment fax 1-855-282-4884, as little as $0 per fill for eligible commercial or private insurance, a Patient Assistance Program, and Urgent Patient Access of 15-day supplies up to 60 days.
Give your patient their plan
A one-page handout for starting Atebrioz, in plain language: what the first fill waits on, the first dates, who will call and the symptoms to report, with blank lines for the start date and your office's number. The link opens the patient's full first 90 days page, where their dates become calendar entries.
trialfriend.com/p/atebriozBefore the first fill: REMS, labs and enrollment
The steps that the pharmacy, the REMS or the drugmaker's program will wait on, in the order they usually need to happen. A first fill of a specialty drug most often stalls on one of these rather than on the plan.
| Step | What it requires | Source |
|---|---|---|
| Confirm the indication | To reduce the volume of total new heterotopic ossification in adults and pediatric patients 12 and older with FOP. Safety and effectiveness below age 12 are not established. | FDA label |
| Verify pregnancy status | Contraindicated in pregnancy. Verify females of reproductive potential are not pregnant before initiating, and advise effective contraception during treatment and for 1 week after the final dose. | FDA label |
| Reconcile medications | Strong CYP3A4 inhibitors mean 50mg once daily. Avoid strong or moderate CYP3A4 inducers and MATE1 or MATE2-K substrates such as metformin. No grapefruit, pomelo or their juices. | FDA label |
| Enroll in MAP | Fax the Patient Enrollment Form with a copy of both sides of the insurance card to 1-855-282-4884. The patient or an authorized representative signs the authorization and enrollment consent on the form. | MAP enrollment form |
| Write the prescription | Atebrioz 25mg tablets, NDC 79378-029-16. The form's default sig is 4 tablets by mouth once daily, quantity sufficient for a 30-day supply, with an Other field for a different dose. | MAP enrollment form |
| Urgent access | Tick the Urgent Patient Access Program box for an immediate, urgent medical need with an access barrier of at least 5 business days. If approved, an initial 15-day supply; patients with a continuing barrier may be eligible for further 15-day supplies up to 60 days in total. | MAP enrollment form |
| Benefits verification and appeals | MAP completes a benefits verification with a coverage overview and answers PA questions. Regional Access Specialists support appeals; the resource library has a sample letter of medical necessity and appeal tips. | MAP for prescribers |
| Availability | Mirum said at approval on September 25, 2026 that it expected US commercial availability in October through MAP. | Mirum press release |
Prior authorization criteria and what to document
No public payer policy with Atebrioz criteria was found as of November 9, 2026. On November 9, 2026 we searched public policies from Express Scripts, FEP Blue, Aetna, Cigna and others and found no Atebrioz criteria. Until plans publish their own, Mirum's checklist lists what a plan without a policy may ask for, such as genetic tests and imaging. That checklist is a drugmaker's guide, not an insurer's rule.
| Element | What the checklist lists | In the chart | Source |
|---|---|---|---|
| Diagnosis | Genetic test results, marked required in Mirum's checklist for plans without a policy | Genetic report | Mirum PA checklist |
| Imaging | CT or MRI results | Radiology reports | Mirum PA checklist |
| Disease background | Size, volume and location of HO, CAJIS score, great toe malformation, current or previous flares, and disability or mobility impairment; age at diagnosis | Chart notes | Mirum PA checklist |
| Prescriber | Endocrinologist, rheumatologist, geneticist, orthopedic specialist or bone specialist, as prescriber or in consult, aware of and in agreement with the plan | Specialty on the request, or the consult note | Mirum PA checklist |
| Drug history | Current and prior FOP treatment or symptom management, with start and stop dates and outcomes | Medication list and notes | Mirum PA checklist |
| Reauthorization | One or more of: imaging showing reduced total new HO volume, unchanged or improved CAJIS, stable flares, steroid use avoided or reduced, stable or improved patient-reported outcomes | Follow-up imaging and notes | Mirum PA checklist |
| Concurrent FOP therapy | Blue Cross Blue Shield of Michigan's Sohonos criteria, published November 1, 2026 and effective January 1, 2027, exclude use with Pasatru or Atebrioz | Dates of any prior or current Sohonos or Pasatru | BCBS Michigan criteria |
| Age | Labeled for 12 and older; the pivotal trial enrolled ages 12 to 64, median 16 | Date of birth on the request | FDA label |
Atebrioz dosing and titration
| When | Label | Source |
|---|---|---|
| Day 1 | 100mg (four 25mg tablets) orally once daily with or without food. Bottles hold 120 tablets with a child-resistant closure, a 30-day supply at this dose. | FDA label |
| With a strong CYP3A4 inhibitor | 50mg once daily; a 120-tablet bottle then covers 60 days. No change with mild or moderate inhibitors. | FDA label |
| Crushed | Mix 4 crushed tablets (100mg) with four tablespoons (60mL) of water, orange juice, applesauce or plain yogurt and administer immediately; do not store the mixture. | FDA label |
| Missed dose | The label and Medication Guide give no missed-dose instruction. | FDA label |
| Renal and hepatic | No adjustment stated in sections 2 or 8. Section 12.3 reports AUC about 64% and 70% higher in moderate and severe renal impairment, 47% and 68% higher in ESRD before and after hemodialysis, and 25% higher in severe hepatic impairment. | FDA label |
| Under 12 | Not established. The PROGRESS record lists Cohort 2 (6 to under 12) and Cohort 3 (2 to under 12); the study is recruiting, with primary completion estimated July 30, 2027. | ClinicalTrials.gov |
| Storage | 20 to 25°C (68 to 77°F), excursions 15 to 30°C; dispense in a tight container. | FDA label |
| Dating period | 24 months from manufacture at 20 to 25°C. | FDA letter |
Monitoring the Atebrioz label requires
| When | What | What the label says to do with it | Source |
|---|---|---|---|
| Before day 1 | Pregnancy status in females of reproductive potential | Required by section 2.1; the Medication Guide tells patients a pregnancy test will be requested | FDA label |
| Any time | Pregnancy | Advise immediate discontinuation and contact with the provider; rat studies showed embryofetal lethality and skeletal malformations at about 3 times clinical exposure | FDA label |
| Through week 24 | Headache, arthralgia, upper respiratory tract infection, epistaxis, nausea | 22%, 22%, 22%, 13%, 13% against 16%, 10%, 10%, 0, 3% on placebo (n = 32 and 31) | FDA label |
| Through week 24 | Gastroenteritis, GERD, iron deficiency anemia, rash (3 patients each), alopecia (2) | None reported on placebo | FDA label |
| Laboratory | Serum iron, hemoglobin, transferrin saturation | Mean increases against placebo, means within normal range; no difference in ferritin change; no signs or symptoms of iron overload through week 100 | FDA label |
| Nonclinical | Rat 6-month study: dose-dependent basophilic foci and hepatic iron accumulation at exposures comparable to clinical | No long-term carcinogenicity studies; clinical relevance, including carcinogenic risk, uncertain | FDA label |
| QT | No clinically significant QT prolongation | At concentrations up to 6.7 times the mean Cmax at 100mg | FDA label |
| Efficacy reference | Total new HO volume on whole-body CT, excluding the head | Week 24 mean change -3.2 cm³ against +24.6 cm³ on placebo; Hodges-Lehmann difference -15.8 cm³ (95% CI -32.1 to -6.0) | FDA label |
Atebrioz drug interactions and contraindications
| Label category | Agents and what the label says | Source |
|---|---|---|
| Strong CYP3A4 inhibitors | Reduce to 50mg once daily; itraconazole raised Cmax 1.28-fold and AUC 2.13-fold | FDA label |
| Moderate CYP3A4 inhibitors | No dose change; ciprofloxacin, erythromycin and fluconazole are predicted to raise AUC 1.50 to 1.78-fold | FDA label |
| Strong or moderate CYP3A4 inducers | Avoid; rifampin lowered Cmax 56% and AUC 79%, and efavirenz is predicted to lower AUC about 60% | FDA label |
| MATE1 and MATE2-K substrates | Avoid, for example metformin; if unavoidable, monitor for adverse reactions and consider reducing the substrate per its labeling | FDA label |
| Grapefruit and pomelo | Do not administer with grapefruit, pomelo or juices containing them | FDA label |
| CYP2D6 inhibitors | Paroxetine and duloxetine are predicted to have negligible effect on exposure | FDA label |
| Other transporters | In vitro inhibitor of OATP1B1, OATP1B3 and OCT2; the label gives no clinical recommendation for these | FDA label |
| Lactation | Breastfeeding not recommended during treatment and for at least 1 week after the final dose | FDA label |
Why a first fill stalls, and the fix
- Prior authorization pending or deniedWe found no public insurer policy for Atebrioz as of November 9, 2026. Mirum's checklist says plans without a policy may ask for genetic test results, CT or MRI images, and chart notes on flare-ups. It also lists a specialist prescriber, or a consult with an endocrinologist, rheumatologist, geneticist, orthopedic specialist or bone specialist.
- The plan said no at firstMAP's Regional Access Specialists work with the specialist's office on the appeal. MAP also offers offices a sample letter of medical necessity and a tip sheet for the appeals process.
- The plan is slow to decideThe prescriber can tick the Urgent Patient Access Program box when an urgent need meets an access barrier of at least 5 business days. If approved, eligible patients get an initial 15-day supply, and a longer barrier may qualify them for up to 60 days.
- Another FOP medicine is on fileBlue Cross Blue Shield of Michigan's criteria, effective January 1, 2027, say Sohonos is not to be used together with Atebrioz or Pasatru. The specialist's office can send the plan the dates of any earlier FOP treatment.
- A copay you cannot payEligible patients with commercial or private insurance may pay as little as $0 per fill through the MAP Savings Program. The Mirum Patient Assistance Program helps people who qualify, and MAP checks eligibility for both.
- Medicare, Medicaid, TRICARE or VA coverageThe enrollment form says patients in a federal healthcare program, including these, may not be eligible for certain Mirum financial assistance programs. The form says eligibility for each program is assessed under federal and state law.
- The patient is under 12The label covers adults and children 12 and older and says safety and effectiveness have not been established in younger children. The specialist can explain what that means for a younger child.
Mirum Access Plus (MAP)
- A Patient Navigator who answers questions about Atebrioz and your insurance coverage and looks for financial assistance
- A benefits check and coverage overview after the enrollment form, and Regional Access Specialists who help the office with prior authorization and appeals
- The MAP Savings Program, as little as $0 out of pocket per fill for eligible patients with commercial or private insurance, subject to program terms
- The Mirum Patient Assistance Program for people who qualify for financial support
- An Urgent Patient Access Program with an initial 15-day supply when an urgent need meets an access barrier, such as a coverage delay, of at least 5 business days, and possibly more up to 60 days in total MAP enrollment form
- Patients in Medicare, Medicaid, TRICARE, VA or another federal program may not be eligible for certain Mirum financial assistance programs MAP enrollment form
- Home delivery from the MAP pharmacy, which calls to confirm your shipping information, with support through every refill Mirum Access Plus
- MAP Mobile, an online tool for prescription updates and refills, which Mirum says will be available to Atebrioz patients in 2027 MAP brochure
Questions prescribers' offices ask about Atebrioz
What is the Atebrioz dose?
100mg orally once daily as four 25mg tablets, with or without food, per the September 2026 label. Tablets may be swallowed whole or crushed into 60mL of water, orange juice, applesauce or plain yogurt and given immediately; do not store the mixture.
When is the Atebrioz dose reduced?
To 50mg once daily with a strong CYP3A4 inhibitor, per the September 2026 label; itraconazole raised zilurgisertib AUC 2.13-fold. No change with mild or moderate inhibitors. Avoid strong or moderate CYP3A4 inducers; rifampin lowered AUC by 79%.
What pregnancy requirements apply to Atebrioz?
Pregnancy is the 1 contraindication in the September 2026 label; verify that females of reproductive potential are not pregnant before initiating. Advise effective contraception during treatment and for 1 week after the final dose, immediate discontinuation if pregnancy occurs, and no breastfeeding until at least 1 week after the final dose.
Does Atebrioz require laboratory monitoring?
The September 2026 label specifies 0 scheduled laboratory tests. Mean serum iron, hemoglobin and transferrin saturation rose against placebo but stayed within the normal range, with no signs of iron overload through week 100; rat hepatic iron accumulation and basophilic foci are of uncertain clinical relevance.
What do insurers ask for to approve Atebrioz?
As of November 9, 2026 we found no public payer policy with Atebrioz criteria, so the September 2026 label's age 12 and older indication is the fixed reference. Mirum's PA checklist for plans without a policy lists genetic test results as required, plus CT or MRI, CAJIS, flare history, prior FOP therapy and a specialist prescriber or consult.
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Sources
- ATEBRIOZ (zilurgisertib) tablets, for oral use, prescribing information and Medication Guide, Revised 9/2026, Mirum Pharmaceuticals, via FDA Drugs@FDA, 2026-09-25.
- NDA 221198 approval letter, Atebrioz (zilurgisertib) tablets, FDA, 2026-09-25.
- FDA Approves Third Treatment for Fibrodysplasia Ossificans Progressiva, FDA, 2026-09-25.
- Mirum Pharmaceuticals and Incyte Announce U.S. FDA Approval of ATEBRIOZ™ (zilurgisertib) for Adult and Pediatric Patients with Fibrodysplasia Ossificans Progressiva, Mirum Pharmaceuticals, 2026-09-25.
- ATEBRIOZ™ (zilurgisertib) Patient Support | Mirum Access Plus®, Mirum Pharmaceuticals, 2026-11-09.
- ATEBRIOZ™ (zilurgisertib) HCP Support | Mirum Access Plus®, Mirum Pharmaceuticals, 2026-11-09.
- ATEBRIOZ (zilurgisertib) Tablets Patient Enrollment Form, September 2026 version, Mirum Pharmaceuticals, 2026-11-09.
- Prior Authorization (PA) Informational Checklist for Atebrioz, October 2026 version, Mirum Pharmaceuticals, 2026-11-09.
- Mirum Access Plus brochure for ATEBRIOZ, September 2026 version, Mirum Pharmaceuticals, 2026-11-09.
- Prior authorization and step therapy coverage criteria, November 2026, Sohonos entry, Blue Cross Blue Shield of Michigan and Blue Care Network, 2026-11-01.
- To Assess the Efficacy, Safety, and Tolerability of INCB000928 in Participants With Fibrodysplasia Ossificans Progressiva (Progress), NCT05090891, ClinicalTrials.gov, record updated October 22, 2026, 2026-10-22.
A reference drawn from the September 25, 2026 label, the drugmaker's published program and one public insurer policy shown as an example, checked on November 9, 2026. Labels and policies change; the label on DailyMed and the plan's current policy govern. Trial Friend is not a medical provider. It reports what these documents say and does not judge whether a drug is safe or right for any patient; that is the prescriber's decision. Not a substitute for the prescribing information.