A study to compare the effectiveness of Intravitreal Bevacizumab (Avastin) with conventional laser for the treatment of stage three plus Retinopathy of Prematurity (ROP) has determined that the anti-VEGH drug showed a significant benefit for zone one but not zone two disease.
The study, known as ‘Bevacizumab Eliminates the Angiogenic Threat of Retinopathy of Prematurity’ (BEAT-ROP) was led by U.S. researcher Helen Mintz-Hittner and reported in the New England Journal of Medicine in February this year.
ROP is a neovascular retinal disorder of childhood that causes loss of vision by means of macular dragging and retinal detachment. A leading cause of childhood blindness in highly industrialised nations, it occurs primarily in infants of low birth weight (≤1250 g; mean, 700 g).
It is a major cause of childhood blindness in developing countries, manifesting in larger premature infants (birth weight ≤2000 g; mean, 1400 g). The worldwide prevalence
of blindness due to retinopathy of prematurity is 50,000.
In her study Prof. Mintz-Hittner enrolled a total of 150 infants with stage three plus retinopathy of prematurity – 67 infants with zone one disease and 83 infants with zone two posterior disease
Zone one ROP has traditionally been treated using laser therapy with success rates in approximately 50 per cent of cases. Inevitably the laser treatment causes permanent loss of the peripheral visual field and often induces clinically significant myopia. When multiple applications of conventional laser therapy fail to induce regression of retinopathy of prematurity, surgery is required.
The use of anti-VEGF agents, primarily intravitreal bevacizumab, is an emerging treatment for acute ROP. The U.S. Food and Drug Administration approved intravenous bevacizumab therapy in 2004 for the treatment of metastatic colon cancer; the drug works by reducing the size and number of new vessels feeding metastases. Off-label use of intravitreal bevacizumab therapy for ophthalmologic neovascular disorders
began shortly thereafter.
In her study Prof. Mintz-Hittner enrolled a total of 150 infants with stage three plus retinopathy of prematurity – 67 infants with zone one disease and 83 infants with zone two posterior disease.
A total of 75 infants were randomly assigned to undergo intravitreal bevacizumab monotherapy, and 75 to conventional laser therapy. Ocular outcomes were later evaluated for recurrent ROP. The rate of recurrence with zone one disease alone was significantly higher with conventional laser therapy than with intravitreal bevacizumab (42 per cent vs. 6 per cent).
However, the rate of recurrence with zone two posterior disease alone did not differ significantly between the laser-therapy group and the bevacizumab group. Additionally, development of peripheral retinal vessels continued after treatment with intravitreal bevacizumab, whereas conventional laser therapy led to permanent destruction of the peripheral retina.
While results were positive for patients with stage three plus ROP in zone one, researchers concluded that the trial was too small to assess the safety issues regarding Avastin in ROP. Further, larger trials will be necessary.
