One in three US patients already on FcRn-antagonist therapy for generalised myasthenia gravis remains inadequately controlled, and that residual pool, not the drug-naive population, is where a new entrant competes.
The funnel starts at an estimated 100,000-200,000 US patients with generalised myasthenia gravis, a wide range that reflects recognised underdiagnosis (roughly 14-20 per 100,000). Serology divides the population sharply: approximately 85% are AChR-antibody positive, about 5% are MuSK-antibody positive, around 2% are LRP4-positive, and 8-10% are seronegative. That split matters commercially because AChR-antibody status gates eligibility for the C5 complement inhibitor class, while the FcRn antagonists carry broader generalised-MG labels that reach across serology lines.
Within the treated population, an estimated 4,000-6,000 US patients are currently on FcRn-antagonist therapy (efgartigimod or rozanolixizumab). Of those, 1,200-2,100, or 30-35%, remain inadequately controlled on an MG-ADL score of 6 or higher despite treatment. This is the pool a new mechanism has to address: patients whose disease appears to involve non-IgG pathways that IgG reduction alone does not resolve. A funnel built only on total prevalence would overstate the near-term addressable population; this model isolates the on-therapy, inadequately-controlled cohort as the sizing anchor.
US gMG funnel - from prevalence to the inadequately-controlled, on-therapy pool
| Funnel Stage | Population | Source |
|---|---|---|
| Estimated US gMG prevalence | 100,000-200,000 | Myasthenia Gravis Foundation of America |
| AChR-antibody positive share | ~85% | Gilhus, NEJM 2016 (PMID 28029925) |
| Currently on FcRn-antagonist therapy | 4,000-6,000 | AXLRx Launch Readiness research base, IQVIA Rx data |
| Inadequately controlled despite FcRn therapy (MG-ADL ≥6) | 1,200-2,100 (30-35%) | AXLRx Launch Readiness research base |
Sources: Myasthenia Gravis Foundation of America epidemiology; Gilhus NE, NEJM 2016 (PMID 28029925); AXLRx Myasthenia Gravis US Launch Readiness research base (IQVIA Rx data, ADAPT extension MG-ADL non-responder data, MGA USA member survey 2023).
What this model answers
Every section answers a named commercial question your team is asking, scoped to your asset.
Delivers
- On-therapy population sizing (4,000-6,000)
- the inadequately-controlled cohort (1,200-2,100, MG-ADL ≥6)
- why this pool, not total prevalence, is the near-term addressable population
Delivers
- Serology distribution (~85%/5%/2%/8-10%)
- the AChR-positive gate on C5 inhibitors
- the broader FcRn label reach across serology lines
Delivers
- 8-sheet structure (Strategic Context, Inputs, Model, Projections, Sensitivity, References, Market Context, QC)
- primary-source citation per conversion step (MGFA, Gilhus NEJM 2016, published launch-readiness research)
Custom model delivered in 72 hours.
Commission This ModelWhat's inside
- Why the inadequately-controlled on-therapy cohort, not total prevalence, sets the addressable pool
- Pressure-tested against the FcRn-inadequate-responder literature before the rest of the model is built out
- 100,000-200,000 estimated US prevalence (MGFA)
- AChR/MuSK/LRP4/seronegative serology split
- Anti-AChR and anti-MuSK serology as the diagnostic anchor
- Neuromuscular specialist referral pathway
- 4,000-6,000 patients currently on FcRn-antagonist therapy
- Serology-gated eligibility for the C5 inhibitor class
- 1,200-2,100 patients at MG-ADL ≥6 despite FcRn therapy
- MuSK-positive and seronegative underserved subgroups
- Which assumptions move the inadequately-controlled pool most
- Scenario ranges across serology segments
- Patient volume by horizon under conservative, base, and aggressive scenarios
- Revenue translation inputs
- The open questions your forecasting team must close before the model is finalised
- Structured for an internal forecast-review session
Included with every brief
How AXLRx builds this model
Prepared by MoatRx analysts.
Every AXLRx patient flow model is built on a five-layer funnel: population, disease burden (E1), diagnosis and specialist capture (E2), treatment and biomarker eligibility (E3), market access (E4), then Year 1-3-5 projections across three scenarios. Delivered as a live Excel workbook, not a static table, with an 8-sheet structure and zero hardcoded cells.
US gMG sources: Myasthenia Gravis Foundation of America epidemiology, Gilhus NE's neuromuscular-junction review in the New England Journal of Medicine, and the underlying research base built for the AXLRx US Launch Readiness assessment, which sources IQVIA prescription data by indication and published FcRn-inadequate-responder analysis.
- US gMG prevalence range and serology split verified against Gilhus NE, NEJM 2016 (PMID 28029925) and Myasthenia Gravis Foundation of America epidemiology
- On-FcRn-therapy population (4,000-6,000) and the inadequately-controlled share (30-35%) verified against the AXLRx Launch Readiness research base
- AChR-antibody gate on C5 inhibitor eligibility verified against FDA Drugs@FDA labelling
Frequently asked questions
Commission this model
AXLRx delivers rare-disease patient flow models built for forecasting and launch teams sizing the US gMG opportunity. Custom model in 72 hours.
Specify your indication, market, and cohort definition.
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Research-verified patient flow model in 72 hours with optional analyst readout.