Neovascular AMD trials and treatment

Landmark Clinical Trials in Neovascular AMD

Modern Anti-VEGF Pharmacological Agents

• Bevacizumab (Avastin, $1.25\,\text{mg}/0.05\,\text{mL}$): Full-length, $149\,\text{kDa}$ humanized IgG1 monoclonal antibody binding all active isoforms of VEGF-A. Used off-label internationally due to extraordinary cost-effectiveness.
• Ranibizumab (Lucentis, $0.5\,\text{mg}/0.05\,\text{mL}$): Recombinant, humanized $48\,\text{kDa}$ Fab antibody fragment targeting all VEGF-A isoforms; lacks the Fc fragment, conferring shorter systemic elimination half-life (~2 hours systemically).
• Aflibercept (Eylea, $2.0\,\text{mg}/0.05\,\text{mL}$): Soluble decoy receptor fusion protein ($115\,\text{kDa}$) combining immunoglobulin-like binding domains of human VEGFR-1 and VEGFR-2 fused to human IgG1 Fc. Possesses roughly 100-fold higher binding affinity for VEGF-A than ranibizumab and bevacizumab, and uniquely binds VEGF-B and Placental Growth Factor (PlGF). The PULSAR trial (2024) approved high-dose Aflibercept ($8.0\,\text{mg}/0.07\,\text{mL}$), demonstrating non-inferiority with 12- to 16-week dosing intervals.
• Brolucizumab (Beovu, $6.0\,\text{mg}/0.05\,\text{mL}$): Single-chain variable fragment (scFv, $26\,\text{kDa}$); small molecular size permits delivery of high molar concentrations ($6\,\text{mg}$ in $0.05\,\text{mL}$). High drying efficacy but burdened by the risk of immune-mediated retinal occlusive vasculitis.
• Faricimab (Vabysmo, $6.0\,\text{mg}/0.05\,\text{mL}$): A pioneering bispecific antibody ($150\,\text{kDa}$) engineered using CrossMAb technology. It simultaneously neutralizes both VEGF-A and Angiopoietin-2 (Ang-2). Ang-2 upregulation in hypoxia destabilizes vascular endothelium by antagonizing the Tie2 receptor; dual inhibition restores endothelial Tie2 signaling, tightens junctional claudins, suppresses vascular leakage, and dampens vascular inflammation.

Clinical Treatment Regimens: PRN vs. Treat-and-Extend (T&E)

Initial loading and maintenance depend on the agent and label. Select a monitored fixed, PRN or treat-and-extend regimen by disease activity, response and follow-up capability.

1. Treat-and-Extend (T&E): The undisputed international standard of care. The patient receives an injection at every scheduled clinical visit. If the macula is completely dry (no subretinal or intraretinal fluid on SD-OCT), the treatment interval is systematically lengthened by $2$ to $4$ weeks (up to a maximum interval of $12$ to $16$ weeks). If recurrent or worsening exudative fluid appears, the interval is shortened by $2$ to $4$ weeks. T&E proactively suppresses neovascular exudation while minimizing clinical visit burden.
2. Pro Re Nata (PRN / As-Needed): Patients are monitored with strict monthly clinical and OCT examinations, receiving injections only when active exudation (new fluid, haemorrhage, or visual decline) is detected. While visually successful in trial settings, PRN in real-world clinical practice results in systematic undertreatment and late visual deterioration due to missed clinic appointments.
3. Fixed Dosing: Fixed bimonthly injections (e.g., aflibercept every 8 weeks) regardless of OCT findings. Rigid and burdens patients with unnecessary injections during quiescent phases while undertreating aggressive lesions.

Supplement and Injection Boundaries

AREDS categories are historical trial categories; modern classification treats geographic atrophy as late AMD, including non-central atrophy. AREDS2 supplementation is considered for appropriate intermediate/advanced-risk groups after medical review. Lutein/zeaxanthin replace beta-carotene, particularly for current or former smokers. A nonsignificant comparison of lower and higher zinc doses does not prove identical effectiveness. High-dose supplements do not prevent every case and are not routine treatment for someone with no AMD.

Use anti-VEGF regimens according to the drug, response and local label. Fixed dosing, PRN with reliable monitoring, and treat-and-extend can all be appropriate; not every agent uses identical loading. OCT fluid, haemorrhage, vision and atrophy contribute to retreatment decisions. Trial names such as PULSAR denote evidence, not a regulatory authority. Blue-light exposure has not been established as a clinical cause of AMD requiring special lenses.