Rezdiffra (resmetirom), the first therapy approved for Metabolic Dysfunction-Associated Steatohepatitis (MASH), received FDA accelerated approval on March 14, 2024 for noncirrhotic NASH/MASH with F2–F3 fibrosis at a WAC of ~$47,400/year (oral, 80 mg or 100 mg daily by weight) and was authorized in the UK by the MHRA on June 3, 2026; US coverage requires prior authorization with documented F2–F3 fibrosis by liver biopsy, VCTE/FibroScan, or MRE — and at least one payer (Excellus BCBS) still deems it not medically necessary, while confirmatory outcomes data (MAESTRO-NASH-OUTCOMES) are not due until 2027.
This article reviews the payer coverage criteria, non-invasive diagnostic requirements, drug-interaction dosing limits, and accelerated-approval risk profiles shaping access to Rezdiffra. For the general mechanisms of benefit routing and prior-authorization setup, see our primers on medical vs pharmacy benefit verification and electronic prior authorization readiness for specialty drugs; for how accelerated approval shapes commercial dynamics, see our analysis of how accelerated approval creates commercial risk before confirmatory failure.
What is Rezdiffra and why was it approved under the accelerated pathway?
Metabolic Dysfunction-Associated Steatohepatitis (MASH) — historically termed Non-Alcoholic Steatohepatitis (NASH) — is a progressive liver disease characterized by hepatic fat accumulation (steatosis), lobular inflammation, ballooning degeneration of hepatocytes, and progressive fibrosis. Without intervention, MASH can progress to compensated and decompensated cirrhosis, hepatocellular carcinoma (HCC), and liver failure.
The pathophysiology of MASH is closely tied to systemic metabolic dysfunction, lipotoxicity, and insulin resistance. Within the hepatocyte, thyroid hormone receptor-beta (THR-beta) is the dominant thyroid hormone receptor subtype, regulating key metabolic pathways including mitochondrial beta-oxidation, cholesterol metabolism, and lipophagy. In MASH, hepatic thyroid hormone activity is localized and downregulated, contributing to lipotoxic injury and cellular dysfunction. Rezdiffra is a first-in-class, orally active, thyroid hormone receptor-beta selective agonist. By targeting the THR-beta receptor, it restores local thyroid hormone activity in the liver, promoting lipid clearance and reducing inflammatory and fibrotic signaling.
Because MASH is a slow-progressing disease where clinical outcomes (cirrhosis, liver failure, death) take decades to manifest, the FDA approved Rezdiffra under the accelerated approval pathway on March 14, 2024. This pathway allows for approval based on a surrogate endpoint that is reasonably likely to predict clinical benefit.
The accelerated approval was supported by the 52-week surrogate endpoint data from the phase 3 MAESTRO-NASH trial (NCT03900429; 966 patients in the primary analysis). The trial evaluated two doses of resmetirom (80 mg and 100 mg orally once daily) against placebo in patients with biopsy-confirmed, noncirrhotic MASH with F2 or F3 fibrosis (moderate to severe fibrosis):
- MASH Resolution (without worsening of fibrosis): Achieved in 25.9 percent of the 80 mg group and 29.9 percent of the 100 mg group compared to 9.7 percent of the placebo group.
- Fibrosis Improvement (by >=1 stage without worsening of MASH): Achieved in 24.2 percent of the 80 mg group and 25.9 percent of the 100 mg group compared to 14.2 percent of the placebo group.
These results demonstrated that resmetirom could simultaneously clear liver fat, resolve active hepatocyte injury (ballooning), and reduce the underlying fibrotic scar tissue, satisfying the FDA's surrogate endpoints.
On June 3, 2026, the UK's Medicines and Healthcare products Regulatory Agency (MHRA) authorized resmetirom for the treatment of adult patients with noncirrhotic MASH with F2–F3 fibrosis. This authorization was granted under the International Recognition Procedure (IRP), which allows the MHRA to leverage approvals from trusted global regulators (in this case, the FDA) to accelerate access for patients in the UK. This transatlantic alignment marks the first authorization of a MASH therapy by a major European regulator, shifting the focus to health technology assessments (such as the NICE evaluation in the UK) to determine NHS funding and reimbursement criteria.
Histological Grading and the NAS Score
For access teams and clinical coordinators, understanding the histological grading systems used in biopsy reports is critical, as payer policies frequently cite these parameters. The primary grading tool is the NAFLD Activity Score (NAS), developed by the NASH Clinical Research Network (CRN). The NAS is a composite score (ranging from 0 to 8) that measures the active necroinflammatory activity of the disease:
- Steatosis (0–3): Graded by the percentage of hepatocytes containing fat droplets (0 = <5%, 1 = 5–33%, 2 = 34–66%, 3 = >66%).
- Lobular Inflammation (0–3): Graded by the number of inflammatory foci per 20x field (0 = no foci, 1 = <2 foci, 2 = 2–4 foci, 3 = >4 foci).
- Hepatocyte Ballooning (0–2): Graded by the presence of degenerating, swollen hepatocytes (0 = none, 1 = few ballooned cells, 2 = many or prominent ballooned cells).
A NAS score of >= 4 is generally considered diagnostic of active MASH, and many payers mandate this score as a prior-authorization baseline. Alongside the NAS score, the CRN staging system measures the structural fibrosis:
- Stage F0: No fibrosis.
- Stage F1: Mild fibrosis (perisinusoidal or portal).
- Stage F2: Moderate fibrosis (perisinusoidal and portal/periportal).
- Stage F3: Severe fibrosis (bridging fibrosis, connecting portal tracts and central veins).
- Stage F4: Cirrhosis (advanced scarring, forming regenerative nodules).
Payers use these definitions to construct their clinical prior-authorization boundaries, approving Rezdiffra only when a biopsy report explicitly states a NAS score >= 4 and a fibrosis stage of F2 or F3, while excluding F0–F1 and F4 patients.
What does Rezdiffra cost and what do patients pay on Part D?
Madrigal Pharmaceuticals set the Wholesale Acquisition Cost (WAC) for Rezdiffra at $3,950 per bottle of 30 tablets, which translates to approximately $47,400 per year. This pricing applies across all three tablet strengths (60 mg, 80 mg, and 100 mg), preventing any cost differences based on weight-based dose titrations:
| Price Parameter | Value | Clinical / Administrative Context |
|---|---|---|
| WAC per 30-day supply | $3,950 | Base acquisition cost for pharmacies |
| Annual WAC | $47,400 | Annual specialty drug spend before discounts |
| Typical Patient Copay (Part D) | Specialty Coinsurance (25–33%) | Patient out-of-pocket exposure during initial coverage phase |
| Medicare OOP Cap (2026) | $2,100 / year | Maximum annual patient out-of-pocket limit under IRA |
Because MASH is strongly correlated with metabolic syndrome, type 2 diabetes, and obesity, the patient population is heavily represented in the Medicare demographic. Under Medicare Part D (pharmacy benefit), oral specialty drugs like Rezdiffra are subject to 25 percent coinsurance during the initial coverage phase (after the 2026 deductible), resulting in a patient out-of-pocket cost of over $1,000 for the first month's fill.
However, under the Inflation Reduction Act (IRA) provisions, Medicare Part D out-of-pocket costs are capped at $2,100 per year for 2026 (the original $2,000 cap set for 2025, adjusted for drug-spending growth). For a Medicare beneficiary, the first one or two fills of Rezdiffra will push the patient through the deductible and initial coverage phases, meeting the $2,100 cap early in the calendar year. After this point, the patient's out-of-pocket cost drops to $0. While this cap improves affordability compared with the previous structure that continued cost-sharing in the catastrophic phase, the initial $2,100 remains a significant financial hurdle for lower-income seniors, requiring active coordination with charitable foundation grants and manufacturer copay assistance.
For patients covered by commercial insurance, Madrigal offers a copay card program that can reduce the patient's out-of-pocket cost to $0. However, commercial plan designs often apply copay accumulator or maximizer programs, which prevent manufacturer copay assistance from counting toward the patient's deductible, extending the period during which the patient remains financially exposed.
What fibrosis-staging documentation do payer PAs require?
Because Rezdiffra is approved only for patients with noncirrhotic MASH with moderate to severe fibrosis (stages F2 and F3), payers have established strict prior-authorization criteria to verify the patient's fibrosis stage. Traditionally, staging required an invasive percutaneous liver biopsy. To avoid the cost, risk, and patient discomfort associated with biopsy, payers accept non-invasive tests (NITs) as sufficient evidence:
- Vibration-Controlled Transient Elastography (VCTE / FibroScan): Measures liver stiffness (kilopascals, kPa). Payers typically require a documented liver stiffness measurement of >= 7.0 kPa to >= 8.5 kPa to confirm F2–F3 fibrosis, while excluding patients with values indicating compensated cirrhosis (typically > 12.5 to 15.0 kPa).
- Magnetic Resonance Elastography (MRE): The gold standard of non-invasive imaging, measuring liver stiffness via shear-wave propagation. A documented liver stiffness of >= 3.0 kPa to >= 3.6 kPa is accepted as evidence of F2–F3 staging.
- Enhanced Liver Fibrosis (ELF) Score: A blood-test panel measuring three serum markers of extracellular matrix synthesis and degradation (hyaluronic acid, procollagen III amino-terminal peptide, and tissue inhibitor of metalloproteinase 1). Payers require an ELF score of >= 9.8 to confirm moderate-to-severe fibrosis.
- Blood-Based Biomarker Panels (FIB-4 / FibroTest / FibroSure): FIB-4 uses age, AST, ALT, and platelet count to calculate a score. While FIB-4 is widely used as a screening tool, payers often require a secondary, more specific test (like VCTE or ELF) to confirm F2–F3 status before approving Rezdiffra, as FIB-4 has a high rate of indeterminate results.
Prescribers must submit the diagnostic report (biopsy pathology, FibroScan trace, or lab report) alongside the PA form. Payer policies explicitly exclude patients with F0–F1 fibrosis (minimal or no disease) and F4 fibrosis (cirrhosis), limiting the eligible patient pool to the noncirrhotic F2–F3 segment.
How do major payers (UHC, Cigna, Prime, VA, Excellus) differ on coverage?
Prior-authorization criteria and formulary placement for Rezdiffra vary across major US commercial, government, and regional payers:
| Payer | Policy Date / Review | Fibrosis Staging Requirements | Key Statin / Dosing Limits | Coverage Status |
|---|---|---|---|---|
| UnitedHealthcare (UHC) | Effective 2/1/2026 | F2–F3 via VCTE, MRE, or biopsy; excludes F4 cirrhosis | Aligns with FDA label for weight-based dosing | Covered with PA; designated specialty pharmacy |
| Cigna National Formulary | Review 4/8/2026 | Documented F2–F3 by biopsy or elastography; reauth at 6 months | Excludes F4 decompensated cirrhosis; statin limits | Covered with PA; requires hepatology/gastroenterology consult |
| Prime Therapeutics | Effective 4/1/2026 | Fibrosis stage F2 or F3 confirmed by liver biopsy or elastography | Restricts statin co-prescribing based on interaction profile | Covered with PA; restricted specialty network |
| Veterans Affairs (VA) | Criteria Jan 2026 | Noncirrhotic F2–F3 confirmed via FibroScan, ELF, or biopsy | Simvastatin max 20 mg; Rosuvastatin max 20 mg | Covered with PA on the VA National Formulary |
| Excellus BCBS | Policy Review 5/14/2026 | F2–F3 staging required | Strict drug-interaction checking | Not Medically Necessary (clinical exclusion) |
The most significant access barrier occurs with regional payers. Excellus BCBS, under its Pharmacy Management Drug Policy (PHARMACY-121, reviewed May 14, 2026), designates Rezdiffra as "not medically necessary" for all MASH indications. The plan argues that while resmetirom improves surrogate histological markers (steatohepatitis resolution and fibrosis staging), long-term clinical trial data showing a reduction in clinical endpoints (such as progression to cirrhosis, hepatic decompensation, liver transplant, or death) are not yet available. This policy effectively excludes coverage for Excellus members, creating a regional access gap and forcing patients to rely on manufacturer-sponsored expanded access programs or patient assistance funds.
Other payers cover the drug under strict prior-authorization criteria. The Cigna policy requires initial authorization for 6 months, with reauthorization at 12-month intervals. To renew, the physician must submit clinical evidence demonstrating a reduction in liver stiffness (VCTE/MRE) or a reduction in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, along with documentation that the patient has experienced no progression to cirrhosis.
Medicaid Policy Variations and Supplemental Rebates
State Medicaid programs exhibit significant variation in their coverage rules for Rezdiffra. Under the Medicaid Drug Rebate Program, states must cover all FDA-approved drugs from participating manufacturers, but they retain the authority to apply prior-authorization criteria.
Several states have negotiated supplemental rebates with Madrigal to place Rezdiffra on their Preferred Drug Lists (PDLs). However, in non-preferred states, prior-authorization criteria often include non-clinical gates, such as:
- Weight-Loss Program Participation: Requiring documented participation in a structured lifestyle or weight-loss program for at least 6 months before drug approval.
- Alcohol Abstinence: Mandating documented abstinence from alcohol for at least 6 months, supported by liver function tests or negative screening questionnaires.
- Prescriber Limitations: Restricting the prescribing physician network exclusively to transplant hepatologists or gastroenterologists, which can create geographic access barriers for rural Medicaid beneficiaries.
Multidisciplinary Care Coordination in MASH Management
Because MASH is a systemic metabolic disease, managing patients receiving Rezdiffra requires close coordination across a multidisciplinary care team. A hepatologist or gastroenterologist typically initiates the diagnosis and staging (performing the biopsy or transient elastography), but the patient's long-term cardiorenal metabolic risk is managed by endocrinologists and primary care physicians.
Furthermore, because resmetirom is an oral pharmacy-benefit drug with a high list price, specialty pharmacists play an essential role in:
- Performing drug-drug interaction screens (specifically statin dosing checks).
- Counseling patients on compliance.
- Coordinating refills to prevent prior-authorization lapses.
Care coordination platforms that link these providers are essential to ensure the patient's diagnostic staging data are shared, statin doses are adjusted, and metabolic comorbidities (such as type 2 diabetes and hypertension) are optimized during the treatment course.
What accelerated-approval risk should access teams monitor through 2027?
Because Rezdiffra was approved based on 52-week surrogate histological endpoints, its long-term commercial viability and coverage status remain subject to accelerated-approval risk. Under the FDA's accelerated approval rules, the manufacturer is obligated to conduct post-marketing confirmatory trials to verify the drug's actual clinical benefit.
Madrigal is currently running the MAESTRO-NASH-OUTCOMES trial (NCT05500222; enrollment target approximately 700 patients). This double-blind, placebo-controlled confirmatory study enrolled patients with well-compensated MASH cirrhosis (stage F4) and is evaluating the time to first clinical event, defined as a composite of:
- Progression to decompensated cirrhosis (ascites, variceal bleeding, hepatic encephalopathy)
- Liver transplantation
- Hepatocellular carcinoma (HCC)
- All-cause mortality
The MAESTRO-NASH-OUTCOMES trial is expected to read out in 2027. This readout represents a critical commercial pivot. If the trial demonstrates a statistically significant reduction in clinical events, the FDA will convert the accelerated approval into a full, traditional approval, and payers are likely to expand coverage (potentially including F4 patients with compensated cirrhosis).
However, if the confirmatory trial fails to show a clinical benefit, or if safety concerns emerge, the FDA has the authority to withdraw the drug from the market. In such a scenario, payers would immediately terminate coverage, and the commercial market for resmetirom would dissolve. Access and formulary planning teams must treat resmetirom as a provisional asset, structuring clinical criteria and specialty pharmacy contracts to accommodate potential labeling changes or market withdrawal in 2027.
What drug-interaction and statin-dosing limits affect real-world use?
Resmetirom is a mild inhibitor of organic anion transporting polypeptides 1B1 and 1B3 (OATP1B1 and OATP1B3), as well as breast cancer resistance protein (BCRP). These transporters are responsible for the hepatic uptake and clearance of many commonly prescribed medications, particularly HMG-CoA reductase inhibitors (statins).
Because MASH patients have a high prevalence of dyslipidemia and metabolic syndrome, a large portion of this population is on chronic statin therapy. Co-prescribing resmetirom increases the systemic exposure (AUC) of statins, raising the risk of concentration-dependent adverse events, particularly myopathy and rhabdomyolysis.
To prevent toxicity, the VA Pharmacy Benefits Management criteria (January 2026) and the FDA label mandate specific statin-dosing limits when co-administered with Rezdiffra:
| Statin | Maximum Permitted Dose with Rezdiffra | Interaction Mechanism | Clinical Monitoring |
|---|---|---|---|
| Rosuvastatin (Crestor) | 20 mg / day | OATP1B1/1B3 & BCRP inhibition | Monitor for muscle pain and creatine kinase (CK) elevation |
| Simvastatin (Zocor) | 20 mg / day | OATP1B1/1B3 inhibition | Assess for myopathy risk; avoid higher doses |
| Atorvastatin (Lipitor) | 40 mg / day | OATP1B1/1B3 & BCRP inhibition | Routine liver function and muscle check |
| Pravastatin (Pravachol) | 40 mg / day | OATP1B1/1B3 inhibition | Lower-potency alternative; monitor tolerability |
For patients receiving high-dose statin regimens (such as rosuvastatin 40 mg daily or atorvastatin 80 mg daily for secondary cardiovascular prevention), the clinic must titrate the statin dose downward before initiating Rezdiffra. Alternatively, the physician must switch the patient to a non-interacting lipid-lowering agent (such as ezetimibe or a PCSK9 inhibitor) if target LDL goals cannot be met at the lower statin dose. This requirement adds clinical management complexity at the specialty pharmacy level, forcing pharmacists to run drug-drug interaction screens before dispensing the medication.
FAQ
Is Rezdiffra covered by Medicare Part D and Medicaid?
Yes. Rezdiffra is covered by Medicare Part D and state Medicaid preferred drug lists (PDLs), subject to prior authorization. Under Part D, patients are subject to specialty tier coinsurance until they meet the $2,100 annual out-of-pocket maximum in effect for 2026 under the Inflation Reduction Act. Medicaid coverage varies by state, with most programs requiring documented F2–F3 fibrosis and enrollment in a metabolic management program.
Does PA require a liver biopsy, or are noninvasive tests accepted?
Almost all major payers (including UnitedHealthcare, Cigna, Prime, and the VA) accept non-invasive tests (NITs) in place of a liver biopsy. The accepted documentation includes transient elastography (FibroScan/VCTE) showing liver stiffness of >= 7.0 to 8.5 kPa, Magnetic Resonance Elastography (MRE) showing >= 3.0 to 3.6 kPa, or an ELF score of >= 9.8.
What happens to coverage if the 2027 confirmatory trial fails?
If the MAESTRO-NASH-OUTCOMES confirmatory trial fails to demonstrate a reduction in clinical endpoints in 2027, the FDA may withdraw Rezdiffra's accelerated approval. Under these circumstances, payers would remove the drug from their formularies and terminate coverage. Access teams should treat current coverage approvals as provisional until the confirmatory data are published.
Sources
- US FDA. Drugs@FDA database. Rezdiffra (resmetirom) accelerated approval record (March 14, 2024) — indications, surrogate endpoints, and regulatory history. https://www.accessdata.fda.gov/scripts/cder/daf/
- Harrison SA, Bedossa P, Guy CD, et al. "A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis." New England Journal of Medicine 2024;390(6):497-509 — pivotal MAESTRO-NASH trial outcomes and efficacy data. https://pubmed.ncbi.nlm.nih.gov/38328143/
- Madrigal Pharmaceuticals. "Rezdiffra Wholesale Acquisition Cost (WAC) Price Transparency Sourcing Form" (Colorado HB 19-1131, March 15, 2024) — pricing structures and package sizes. https://www.madrigalpharma.com/wp-content/uploads/2024/03/US-PP-RES-00089-Resmetirom-Price-Transparency-by-State-Form-Colorado.pdf
- UnitedHealthcare. "Rezdiffra (resmetirom) Prior Authorization and Medical Necessity Policy" (Effective February 1, 2026) — elastography metrics, diagnostic criteria, and exclusion lists. https://www.uhcprovider.com/content/dam/provider/docs/public/prior-auth/drugs-pharmacy/commercial/r-z/PA-Med-Nec-Rezdiffra.pdf
- GOV.UK / Medicines and Healthcare products Regulatory Agency (MHRA). "Resmetirom (Rezdiffra) authorised to treat Metabolic Dysfunction-Associated Steatohepatitis (MASH) in adults" (June 3, 2026) — IRP authorization and UK indication. https://www.gov.uk/government/news/resmetirom-rezdiffra-authorised-to-treat-metabolic-dysfunction-associated-steatohepatitis-mash-in-adults
- Veterans Affairs (VA) Pharmacy Benefits Management Services. "Resmetirom (Rezdiffra) Clinical Prior Authorization Criteria" (January 2026) — statin dosing limits, fibrosis-staging criteria, and diagnostic biomarkers. https://www.pbm.va.gov/clinicalguidance/druganalysis.asp
- Cigna National Formulary. "Hepatology - Rezdiffra Prior Authorization Policy" (Reviewed April 8, 2026) — reauthorization criteria, F4 cirrhosis exclusions, and trial timeline references. https://static.cigna.com/assets/chcp/pdf/coveragePolicies/cnf/cnf_852_coveragepositioncriteria_hepatology_rezdiffra_pa.pdf
