Reducing the treatment burden in AMD: individualizing treating?

Recent pharmacologic advances have increased the armamentarium of clinicians who treat age-related macular degeneration (AMD), said Scott W. Cousins, MD, professor of ophthalmology and immunology, Duke Center for Macular Disease, Raleigh, NC. In his presentation "Update on initiating treatment for neovascular AMD," Dr. Cousins focused on the treatments available for typical subfoveal choroidal neovascularization (CNV) and how the advances have modified treatment plans.

Photodynamic therapy was the first pharmacologic breakthrough in treating AMD. Extensive evaluation ultimately revealed that numerous applications were needed to achieve significant visual stability compared with observation alone. The treatment burden and costs were both acceptable to patients, Dr. Cousins noted.

Vascular endothelial growth factors (VEGF) were the next big breakthrough with pegaptanib (Macugen, Pfizer Ophthalmics), the first agent that was found to bind one isoform of VEGF, namely, VEGF-α₁₆₅, followed by ranibizumab (Lucentis, Genentech), which blocked all five isoforms of VEGF. Ranibizumab was first evaluated to treat classic and predominantly classic lesions in the ANCHOR Study and later minimally classic and occult lesions in the MARINA Study. The ANCHOR Study found that the visual acuity was stabilized in 96% of eyes (less than a three-line loss of visual acuity) and 40% of eyes had a three-line improvement in vision and maintained that increase for 1 year, Dr. Cousins recounted. The results in the MARINA Study were very similar (90% and 33%, respectively). In addition, the visual acuity improvement occurred rapidly after three injections.

"Ranibizumab resulted in a paradigm shift," Dr. Cousins noted. "The study found that scheduled monthly injections can provide sustained visual improvement of three or more lines in 40% of patients for 2 years. However, the cost is very high."

Results of the evaluation of ranibizumab in the PIER Study raised the question of reducing treatment burden by modifying treatment based on the retinal status of the patient. The study tested injecting three doses of the drug followed by quarterly care. The reduced treatment approach provided stable vision but no three-line increase in vision. The impact of this type of approach must be further evaluated, according to Dr. Cousins.