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Inluriyo / imlunestrant for eSR1-Mutated Advanced or Metastatic Breast Cancer After Endocrine Therapy

As of February 2026, MARA’s assessment finds Inluriyo / imlunestrant’s reimbursement risk concentrated in cost effectiveness, with care pathway integration a strength; the current MARA Rating and full rationale are available in the report.

The assessment also weighs resource use and cost implications: what the drug adds to, or removes from, the wider bill beyond its own price — administration, monitoring, hospital time. The strength recorded in care pathway integration carries weight because that domain asks how the drug fits into the way care is organised today; a treatment that demands new infrastructure or displaces an established pathway faces extra scrutiny.

Oncology

This rating sits within MARA’s Oncology coverage, alongside 153 other independently assessed treatments in the same area.

What payers will ask

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

Imlunestrant demonstrated a statistically significant improvement in progression-free survival (PFS) compared to standard endocrine therapies (fulvestrant or exemestane) in the ESR1-mutated population, with a median PFS of 5.5 months versus 3.8 months (HR 0.62, p=0.0008). This evidence is derived from a Phase 3 trial (EMBER-3), which is a strong indicator of clinical effectiveness.

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

No cost-effectiveness analyses or incremental cost-effectiveness ratios (ICERs) were identified in the document. The lack of economic evaluations leaves the cost-effectiveness of imlunestrant unassessable, which is a significant limitation for market access.

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

The document lacks comprehensive data on health-related quality of life, with no validated instruments reported and only limited information on patient-reported outcomes. The absence of relevant HRQoL data indicates a critical gap in understanding the treatment’s impact on patient well-being.

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

Imlunestrant has an acceptable safety profile, with serious adverse reactions reported in 10% of patients and fatal adverse reactions in 1.8%. The adverse events are comparable to those of standard therapies, indicating manageable safety concerns.

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

The EMBER-3 trial compared imlunestrant to standard endocrine therapies (fulvestrant or exemestane), which are appropriate comparators. However, the absence of head-to-head comparisons with other oral SERDs limits the robustness of the evidence.

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

The trial population is well-defined, consisting of patients with ESR1 mutations who have progressed after endocrine therapy. The demographic data provided indicates a representative sample, although subgroup analyses are limited.

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

Imlunestrant can be integrated into existing care pathways with minimal disruption, as it is administered orally and requires standard monitoring. The use of a companion diagnostic for patient selection further supports its integration.

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

The document does not provide any direct evidence regarding resource use or cost implications associated with imlunestrant. This lack of information raises concerns about the economic viability of the treatment.

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

The evidence is based on a Phase 3 randomized controlled trial (EMBER-3), which is a strong design. However, there are documented limitations regarding eligibility criteria and deviations, which affect the overall robustness of the evidence.

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

While there are some sensitivity analyses reported, significant uncertainties remain regarding long-term outcomes and the impact of the treatment on broader health system factors. This uncertainty may limit the treatment’s acceptance in some markets.

Be alerted when this rating changes:

Sample two-page MARA Rating report for the fictional drug Samplinib: the rating with its decision record, and the ten graded payer questions with the reasoning behind each
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Public record

The entries below are official decisions and assessments concerning this drug and indication, listed with their dates as a matter of record. The assessment on this page reflects the evidence available as of its date.

  • 18 June 2026 — United Kingdom (NICE), technology appraisal TA1168: evaluation ended without a recommendation after the company did not provide an evidence submission. official record
  • 3 September 2026 — Germany (G-BA), benefit assessment: hint of a non-quantifiable additional benefit in one subpopulation; no additional benefit proven in the others. official record
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