A study published February 17 issue of the New England Journal of Medicine has shown that the blood vessel-inhibiting cancer drug bevacizumab (Avastin) is effective for treating retinopathy of prematurity (ROP), an eye disorder that is a leading cause of blindness in children worldwide. Retinopathy of prematurity occurs when excess blood vessels grow into the retina before an infant’s eyes have developed completely. In severe cases, the retina can completely detach, resulting in permanent vision loss. Physicians at the University of Texas Health Science Center at Houston Medical Center performed this study.
The excess blood vessel growth in ROP is stimulated by a lack of oxygen in the eye (hypoxia), which spurs the growth of abnormal blood vessels (angiogenesis). A number of major diseases are characterized by excessive angiogenesis, including most forms of cancer and age-related wet macular degeneration (AMD), a leading cause of vision loss in the elderly. Bevacizumab inhibits a critical angiogenesis-stimulating protein called vascular endothelial growth factor (VEGF), and is used to treat several types of cancer as well as wet AMD.
In the study, 150 infants were randomized to receive intravitreal (into the eye) injections of bevacizumab, or laser therapy, the standard treatment for ROP. Laser therapy is successful in about half of ROP cases, but causes permanent loss of peripheral vision. The infants in the study had posterior stage 3+ ROP classified as zone I (affecting the part of the retina immediately surrounding the optic nerve) or zone II (the area surrounding zone I). Stage 3+ ROP indicates that two or more quadrants of the eye have dilated veins and tortuous arteries near the optic disk.
Among infants with zone 1 ROP, the most difficult form to treat, the rate of disease recurrence was significantly lower with intravitreal bevacizumab (6%) compared with laser therapy (42%). Although the study was too small to assess the safety of bevacizumab injections, the physicians observed no local or systemic side effects in the infants that they could attribute to the drug.
A major advantage of intravitreal bevacizumab therapy is that it can be administered at the bedside by an eye doctor. By contrast, laser therapy for ROP is a much more invasive and expensive procedure that requires specialized training and equipment. Further, laser therapy in the study resulted in permanent destruction of useful blood vessels that support peripheral vision, while bevacizumab allowed for the continued growth of healthy blood vessels in the eye, which is consistent with other case studies. While additional research is required to determine the optimal dosing of bevacizumab for different disease stages, these findings may represent a major advance for the treatment of ROP.
# # #