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Neovascularization is responsible for severe vision loss in patients with age-related macular degeneration (AMD). A promising approach to this problem is to inhibit vascular endothelial growth factor (VEGF), which promotes angiogenesis. In two industry-sponsored trials, researchers examined the effect of ranibizumab — a monoclonal antibody that neutralizes VEGF — in patients with AMD.
In one study, researchers randomized 716 AMD patients with neovascularization to receive monthly intravitreal injections of ranibizumab (either 0.3 or 0.5 mg) or placebo. At 12 months, 95% of patients in both ranibizumab groups, but only 62% of patients in the placebo group, lost fewer than 15 letters from baseline visual acuity, or about three lines on a standardized vision chart (the primary endpoint). Moreover, visual acuity improved by 15 or more letters in 25% and 34% of patients, respectively, in the two ranibizumab groups, but in only 5% of placebo recipients. Endophthalmitis developed in five ranibizumab recipients (about 1%) and in no placebo recipients.
The second study was almost identical to the first, except that an active comparison treatment (photodynamic therapy) was used instead of placebo. Results were similar to those of the first study, with ranibizumab being far more effective than photodynamic therapy.
Rosenfeld PJ et al. Ranibizumab for neovascular age-related macular degeneration. N Engl J Med 2006 Oct 5; 355:1419-31.
Brown DM et al. Ranibizumab versus verteporfin for neovascular age-related macular degeneration. N Engl J Med 2006 Oct 5; 355:1432-44.
Steinbrook R. The price of sight — Ranibizumab, bevacizumab, and the treatment of macular degeneration. N Engl J Med 2006 Oct 5; 355:1409-12.
Stone EM. A very effective treatment for neovascular macular degeneration. N Engl J Med 2006 Oct 5; 355:1493-5.
Comment
Ranibizumab recently was FDA-approved and already is being used for treatment of AMD. An interesting and developing controversy concerns the cost of this drug — nearly US$2000 per 0.5 mg dose. The closely related drug bevacizumab (Avastin) is FDA-approved only for treatment of metastatic colorectal cancer, but some ophthalmologists are using intravitreal injections of this drug to treat AMD, apparently successfully and at a fraction of the price of ranibizumab. Two editorialists discuss this controversy and the need for a trial to compare the two drugs.