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Controversial Study Uses Avastin (Bevacizumab) to Treat Age-related Macular Degeneration: Presented at AAO
By Earl R. Nichols
CHICAGO, IL -- October 18, 2005 -- The use of Avastin (bevacizumab) in the treatment of age-related macular degeneration (AMD) is here to stay, even though it is an off-label application, according to a keynote presentation here at the annual meeting of the American Academy of Ophthalmology (AAO).
Avastin has been used in the treatment of colorectal cancer since 2004 and has the same mechanism of action in the retina as it does in cancerous tumors -- it blocks the formation of new blood vessels which in cancer lead to metastasis and in macular degeneration protrude through the retina, leading to blindness.
Philip Rosenfeld, MD, Associate Professor of Ophthalmology, University of Miami Miller Medical School, Miami, Florida, United States, presented study findings on the use of Avastin in patients with AMD.
Dr. Rosenfeld and colleagues studied 40 patients who had severe AMD and who received a mean of 1.8 injections of Avastin each as salvage therapy.
Results show a mean decrease in retinal thickness of 104 microns, from 332 microns at baseline to 228 microns.
Patients also had an improvement in visual acuity, from a mean of 20/160 to 20/125, which corresponds to an increase of one line of visual acuity in 40% of subjects, Dr. Rosenfeld said.
While the full side effect profile of Avastin has not been evaluated in the ocular setting, Dr. Rosenfeld said the drug has been tested in humans at doses ranging from 1.0 to 2.5 mg with no evidence of inflammation resulting.
The most significant side effect seems to be transient changes in blood pressure. In a sub-group of 18 patients, there was a spike of 11 mmHg in systolic blood pressure and 7.5 mmHg in diastolic blood pressure around three to four weeks post-treatment. This seemed to resolve by the end of the 24-week study, however, so at the study end-point, there was a net decrease in systolic pressure of 6.5 mmHg and a net decrease in diastolic pressure of 1.4 mmHg. The decrease in diastolic pressure was not significant, but the change in systolic pressure was, Dr. Rosenfeld said.
Dr. Rosenfeld said that what sets Avastin apart from a drug like Macugen, which is also used in the treatment of AMD is that Macugen costs $3300 US per mg, while Avastin costs $5.50/mg.
The results seen in these trials are "too promising, and the price is too attractive", Dr. Rosenfeld said. Nonetheless, the product still needs to be evaluated in more carefully designed trials, and especially, it needs to be compared with Lucentis another human monoclonal antibody that is being developed for the treatment of macular degeneration.
[Presentation title: Avastin for AMD. Retina Sub-specialty day]
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