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Cenobamate / ontozry for treating focal onset seizures in epilepsy

This rating has a newer version, as of July 2025 — read the current report. This page stays on the record as originally published.

As of May 2025, MARA’s assessment finds Cenobamate / Ontozry’s reimbursement risk concentrated in uncertainty, sensitivity, and broader impacts, with patient population and subgroups a strength; the current MARA Rating and full rationale are available in the report.

The assessment also weighs comparator selection: whether the drug was tested against the treatment payers actually fund today; a benefit shown against the wrong comparator carries little weight in a reimbursement decision. The strength recorded in patient population and subgroups carries weight because that domain asks how closely the trial population matches the patients who would receive the drug in practice; payers often restrict funding to the groups where the evidence is strongest.

Neurology

This rating sits within MARA’s Neurology coverage, alongside 61 other independently assessed treatments in the same area.

What payers will ask

Is the clinical benefit the kind payers reward? — Clinical effectiveness

Cenobamate shows moderate benefit in reducing seizure frequency, with 40.2% to 64.2% of patients achieving at least a 50% reduction in seizures across different doses in clinical trials. However, the evidence is limited to short-term studies and lacks direct comparisons with other treatments, leading to a modest margin of benefit.

Does the economic case hold at the expected price? — Cost effectiveness

Cenobamate is considered cost-effective, with an ICER of £20,522 per QALY gained, which is within acceptable thresholds for Healthcare resources. The committee concluded that cenobamate dominates other treatments, being both more effective and less costly in certain scenarios.

Is there quality-of-life evidence payers weigh? — Quality of life

While cenobamate may improve seizure control, the evidence regarding its impact on HRQoL is limited and mixed. The clinical experts noted that a 50% reduction in seizures may not significantly enhance daily functioning or independence, indicating minimal or uncertain impact on quality of life.

Does the safety profile hold up for payers? — Safety and Adverse Effects

Cenobamate has an acceptable safety profile, with adverse events primarily being mild to moderate. However, there are concerns about the potential for higher rates of treatment-emergent adverse events compared to some comparators, which necessitates cautious use.

Was the drug compared against what payers expect? — Comparator Selection

The comparators selected for the network meta-analysis were primarily ‘third generation’ medicines, which may not fully represent the range of available treatments. The committee noted that older treatments were not adequately considered, leading to potential gaps in the evidence base.

Is the population defined the way payers need it? — Patient Population and Subgroups

The patient population in the trials is broadly representative of those likely to receive cenobamate in clinical practice, with high baseline seizure rates. However, the exclusion of individuals with psychiatric comorbidities may limit generalizability.

Does the drug fit how care is delivered and paid for? — Care Pathway Integration

Cenobamate can be integrated into existing care pathways with minor adjustments, as it is administered once daily, which is more convenient than many other antiseizure medications. This ease of integration supports its use in clinical practice.

Are the wider system costs understood? — Resource Use and Cost Implications

The resource use estimates provided by the company were based on clinical opinion and may overestimate costs. The committee expressed concerns about the validity of these estimates, indicating a moderate risk in resource implications.

Would the evidence survive payer scrutiny? — Evidence Quality and Robustness

The evidence base includes two randomized controlled trials, which provide a strong foundation for the assessment. However, the reliance on short-term data and the absence of long-term comparative evidence introduce some methodological concerns.

How exposed is the case to uncertainty? — Uncertainty, Sensitivity, and Broader Impacts

There are significant uncertainties regarding the long-term effectiveness and safety of cenobamate, particularly due to the potential for attrition bias in the open-label studies. This uncertainty may restrict its use until more data is available.

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