Treatment Failure Criteria for Izervay
The FDA label for Izervay does not explicitly define treatment failure criteria, but based on clinical trial data and established ophthalmic practice patterns, treatment failure should be considered when there is continued rapid progression of geographic atrophy (GA) despite therapy, development of serious adverse events precluding continued treatment, or conversion to neovascular AMD requiring alternative management.
Primary Indicators of Treatment Failure
Lack of Therapeutic Response
- Continued rapid GA progression despite monthly Izervay injections, particularly if the rate of GA growth approaches or exceeds the expected untreated rate of ~2.6 mm²/year 1
- In the GATHER trials, Izervay reduced GA growth by 14-35% compared to sham 1. If a patient shows no reduction in progression rate after 6-12 months of consistent treatment, this suggests inadequate response
- Progressive ellipsoid zone (EZ) degradation without slowing despite treatment may indicate failure, as Izervay significantly reduces EZ attenuation by 19.5% and partial EZ degradation by 55.3% in responders 2
Safety-Related Treatment Discontinuation
The FDA label identifies several adverse events that would necessitate stopping treatment 1:
- Endophthalmitis (occurred in 0.02% per injection in real-world data 3)
- Retinal detachment
- Persistent intraocular pressure elevation requiring discontinuation (occurred in 1.0% of eyes 3)
- Severe ocular inflammation that cannot be managed
Conversion to Neovascular AMD
- Development of choroidal neovascularization (CNV) occurred in 7% of monthly Izervay patients at 12 months and 12% at 24 months 1
- While not strictly a "failure," conversion to wet AMD represents a change in disease trajectory requiring addition of anti-VEGF therapy
- Real-world data shows conversion rates of 3.6-5.4% (4.3-6.7% annualized), with higher risk in patients whose fellow eye has neovascular AMD 3
Practical Assessment Timeline
Monitor at these intervals:
- Baseline fundus autofluorescence (FAF) to measure GA area
- Month 6: Reassess GA growth rate via FAF
- Month 12: Calculate annualized growth rate and compare to expected treatment effect
Red flags suggesting failure:
- GA growth rate >2.2 mm²/year (approaching untreated rates)
- No measurable reduction in growth rate compared to estimated baseline trajectory
- Development of vision-threatening complications
- Persistent ocular adverse events after 2-3 injections
Important Caveats
Do not confuse expected adverse events with treatment failure:
- Conjunctival hemorrhage (13%), transient IOP elevation (9%), and transient blurred vision (8%) are common but manageable 1
- These typically do not require discontinuation
The diabetic retinopathy guideline 4 provides a framework for anti-VEGF failure that can be adapted: definite worsening despite treatment, or after 12 months of treatment with no improvement in anatomic measures. However, this was for DME, not GA, so direct application requires clinical judgment.
Key difference from other retinal diseases: Unlike neovascular AMD where visual acuity is the primary endpoint, GA treatment success is measured by slowing anatomic progression. Stable or slowly declining vision may still represent treatment success if GA growth is slowed.